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THE

VELIGER

A Quarterly published by

CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC.
Berkeley, California

R. Stohler, Founding Editor

Volume 27

July 2, 1984 to April 1, 1985

TABLE OF CONTENTS
Number 1 (July 2, 1984)

Aggregation in a tropical neritid.
STEPHEN D. GARRITY AND SALLY C. LEVINGS .. 1
Establishment of mussel beds: attachment behavior and
distribution of recently settled mussels (Mytilus cali-
fornianus).
JAMES H. PETERSEN
Observations on the spawn of three species of Conus from
the Golfo Triste, Venezuela.
PABLO Es RENCHASZADEH(: gee tients) .an 14
The rhythmic activity of Nautilus pompilius, with notes
on its ecology and behavior in Fiji.

ILEON: Pee Zc ANNs .g:teg os asta) nce ogee Oneal yearemtre 19

Form and function of the radulae of pleurotomariid gas-
tropods.

CAROLE S-EICK MAN: Gisele as inion do ree 29

The Pleurobranchidae (Opisthobranchia: Notaspidea) of
the Marshall Islands, central-west Pacific Ocean.
IRE Ge Wile GAIN Git cae cee or crane eres eae es Sy
x

A new species of Gastropteron from Florida (Gastropoda:
Opisthobranchia).
TTERRENCE M. GOSLINER AND PATRICIA T. ARMES.. .
MAb Me eee oe 54
Notes on the tergipedid nudibranchs of the northeastern
Pacific, with a description of a new species.
DAVID W.. BEHRENS. 34,5 )4C oe eee 65
The morphology, reproduction, and ecology of the com-
mensal bivalve Scintillona bellerophon spec. nov. (Gal-
eommatacea).

DIARMAID O FoIGHIL AND ALLAN GIBSON .... . 72
A new species of leptonacean bivalve from off northwest-
ern Peru (Heterodonta: Veneroida: Lasaeidae).

JOSEPH ROSEWATER
Vitrea contracta (Westerlund) and other introduced land
mollusks in Lynnwood, Washington.

BARRY ROTH AND TIMOTHY A. PEARCE ....... 90
Determining the area of a gastropod’s foot.
RONALDIV. DIMOCK) RY a. eee ee eee 93

Number 2 (October 5, 1984)

Culture of the California red abalone Haliotis rufescens
Swainson (1822) in Chile.
Buzz Owen, Louis H. DISALVvo, EARL E. EBERT, AND
TGRIKASE ONCK 225 a aciserae ctu ean es 101
Multivariate analysis of geographic variation in Cypraea
caputserpentis (Gastropoda: Cypraeidae).

BRIANTUN y MeISSOD 2.1 .r. 3p sh whet geet eect este a oe 106
Seasonal variation in biochemical composition of the fresh-
water pond snail Viviparus bengalensis Linnaeus.

P. K. GupTa AND V. S. DURVE 120
Gonadal organization and gametogenesis in the fresh-water
mussel Diplodon chilensis chilensis (Mollusca: Bival-
via).
SANTIAGO PEREDO AND ESPERANZA PARADA .... 126
The effects of aerial exposure and desiccation on the oxy-
gen consumption of intertidal limpets.
ALASTAIR J. INNES 134
Predator deterrence by flexible shell extensions of the horse
mussel Modiolus modiolus.
Mary M. WRIGHT AND LISBETH FRANCIS 140
The opisthobranchs of Cape Arago, Oregon, with notes
on their biology and a summary of benthic opistho-
branchs known from Oregon.
JEFEREY Elo ReiGODDARD eee ne ener

il

Comparison of Acteocina canaliculata (Say, 1826), A. can-
dei (d’Orbigny, 1841), and A. atrata spec. nov. (Gas-
tropoda: Cephalaspidea).

PAUL S. MIKKELSEN AND PAULA M. MIKKELSEN ....
womle Pax active acavelle 4 le eye) eee 164

Pseudo-operculate pulmonate land snails from New Cal-
edonia.

ALAN SOLEM, SIMON TILLIER, AND PETER MORDAN
OMe inp ahegee Aes 2 193

Lysinoe (Gastropoda: Pulmonata) and other land snails
from Eocene-Oligocene of Trans-Pecos Texas, and
their paleoclimatic significance.

BARRY ROTH 200

The genera Moelleria Jeffreys, 1865, and Spiromoelleria
gen. nov. in the North Pacific, with description of a
new species of Spiromoelleria (Gastropoda: Turbini-
dae).

RAE BAXTER AND JAMES H. MCLEAN......... 219

The Bernardinidae of the eastern Pacific (Mollusca: Bi-
valvia).

EUGENE COAN 227

A technique for determining apparent selective filtration
in the fresh-water bivalve Elliptio complanata (Light-
foot).

COLIN G. PATERSON

Number 3 (January 2, 1985)

Form, function, and origin of temporary dwarf males in
Pseudopythina rugifera (Carpenter, 1864) (Bivalvia:
Galeommatacea).

DIARMAID O FoIGHIL 245

Life-habits and infaunal posture of Cumingia tellinoides
(Tellinacea, Semelidae): an example of evolutionary
parallelism.

W. D. RUSSELL-HUNTER AND JAy S. TASHIRO.. 253
Patterns of sex change of the protandric patellacean lim-
pet Lottia gigantea (Mollusca: Gastropoda).

DavipD R. LINDBERG AND WILLIAM G. WRIGHT

PS Reet od Fk aioe a en wi a 261
Sediment correlates to density of Crepidula fornicata Lin-
naeus in the Pataguanset River, Connecticut.
STEPHEN H. LOOMIS AND WENDY VANNIEUWEN-
MP ie ce ee os ee RRA 266
Histopathological and histochemical effects of larval trem-
atodes in Goniobasis virginica (Gastropoda: Pleuro-
ceridae).
JANE E. HUFFMAN AND BERNARD FRIED 273
Architectonica (Architectonica) karsteni (Rutsch, 1934): a
Neogene and Recent offshore contemporary of A.
(Architectonica) nobilis Réding, 1798 (Gastropoda:
Mesogastropoda).
THOMAS J. DEVRIES

The Stenoplax limaciformis (Sowerby, 1832) species com-
plex in the New World (Mollusca: Polyplacophora:
Ischnochitonidae).

ROBERM CABULEOCKG rae a sri Goi 291

A comparison of two Florida populations of the coquina
clam, Donax variabilis Say, 1822 (Bivalvia: Donaci-
dae). II. Growth rates.

PAUL S. MIKKELSEN 308

Comparative shell microstructure of North American Cor-
bicula (Bivalvia: Sphaeriacea).

ROBERT S. PREZANT AND ANTONIETO TAN-TIU

mans Pre ait abuse Re eee Seat Urano narnia 312
A new species of Sphenia (Bivalvia: Myidae) from the
Gulf of Maine.
RoBERT W. HANKS AND DAVID B. PACKER..... 320
An anesthetic for internal operations on the land snail
Helix aspersa Miller.
DANIEL CHUNG 331
Two new northeastern Pacific gastropods of the families
Lepetidae and Seguenziidae.

JAWS Jal, IMIGIDININ G Gas eo oes eusldd se gu veo oe 336
Soviet contributions to malacology in 1979.
Morris K. JACOBSON AND KENNETH J. Boss... 339

Number 4 (April 1, 1985)

Adaptive value of shell variation in Thavs lamellosa: effect
of thick shells on vulnerability to and preference by
crabs.

I N@INICHARIDEPAEMER 6 52 2 nt). eh ek os Qe wee 349

Gastropod feeding tracks as a source of data in analysis
of the functional morphology of radulae.

CAROLE S. HICKMAN AND ToM E. Morris..... Si)
Predation by Nucella cingulata (Linnaeus, 1771) on mus-
sels, particularly Aulacomya ater (Molina, 1782).
Patti A. WICKENS AND CHARLES L. GRIFFITHS .....

ee re he a eh ae as 366

The activity pattern of Onchidella binney: Stearns (Mol-
lusca: Opisthobranchia).

PHILIP J. PEPE AND SUEANNE M. PEPE 375

A mass mortality of northern bay scallops, Argopecten
irradians irradians, following a severe spring rain-
storm.

STEPHEN T. TETTELBACH, PETER J. AUSTER, EDWIN
W. RHODES, AND JAMES C. WIDMAN 381

Shell growth, trauma, and repair as an indicator of life
history for Nautilus.

JouN M. ARNOLD

Records and morphology of Lomanotus stauber: Clark &
Goetzfried, 1976, from the Panamic Pacific.
TERRENCE M. GOSLINER AND HANS BERTSCH .. 397
Rediscovery and redescription of Rostanga lutescens (Bergh,
1905), comb. nov. (Gastropoda: Nudibranchia).
SCOTT JOHNSON AND Hans BERTSCH 406
Patelloida chamorrorum spec. nov.: a new member of the
Tethyan Patelloida profunda group (Gastropoda: Ac-
maeidae).
Davip R. LINDBERG AND GEERAT J. VERMEIJ.. 411
A new species of Cuthona from the Gulf of California.
DAV IDES EEIRIENS a ihee ce ree curtis. pee eteia oe 418
Three new species of Lepidozona (Mollusca: Polypla-
cophora) from the Gulf of California.
ENNIO) Ifo INAIVHIVNG Bo oo clsaagacdaucsous c+ 423
Review of the west coast aspelloids Aspella and Dermo-
murex (Gastropoda: Muricidae), with the description
of two new species.
EAN AMIE WOKE Sry Sek Shey eerste nek: 430
A distributional list with range extensions of the opis-
thobranch gastropods of Alaska.
RICHARD S. LEE AND Nora R. FOSTER. .......

440

AUTHOR INDEX

HARMES Res ois Al ao) 22) 2) hs ena ee eg 54
ARNOLD Seu Min oe. Mice rmeceeah erie Cee ea ae 386
MUSTER, Pion ah piste acute ate art ole cae eee ante 381
BAXTER GR 6S < nb aes eae 5 0h 7a eee pee es 219
IBEHRENS® DD) Win ae oe eer rece ene ean 65, 418
IBERTSCH bd fe crshterec. | ia anes chee eee nae 397, 406
BOSS 50K ey See alee clinay 5 clas) each seopemeeeusyen Bacyaredn 339
BULLOCK SRG. ciaiee, Beha oo a ee eee 291
GHUNGs DE ease ere i ae et a ee EEE 331
GOANIIE ar, eh oe on ee Bee eae ee ear rare 227, (244)
BEVRIES (RAYS are | holy eee setreheh tena rai 282
DIMOCKIERE ViZayRe enantio aes ee erie 93
DISAE VON Ios Flee Oars hams ieee Meee ae 101
TOWIRV ESS Wie iS cased cae le tee ea arn lire ee ee ara 120
BER SES bis, “coe ao sree en ern tal ata ae eee ane ap 101
PERREIRAG AC ee Seca. acess talon arate sienna area te 423
RONCK CB ir tit on ako in cei oe Mar ee 101
IOSTRER. ING JRie Elta Sse ee eee ee 440
ESRIAN GIS Gea: wets, oete, hace eee ete ee ENR ee 140
FRIED) By se dcnale ade hia naan eee ee ee 273
GARRIT Ys (SoD i earths enn ee nets eintaeateer 1
GIBSON AG tries Oe Oe aE ener YP
GODDARD) HOR jo -raties e eee ee 143
(GOSTINE Reeds en real en ae 54, 397
GRIPPITHS, Cr: Ta See eed oe anaes ae hee 366
GUPTARPAIKG) Sao Mire tee 0 cn retain ae ena 120
GLANS R& SW 0. a 25 ates ot ree eer a ee 320
FETC KMUAIN a GS ee ee ee oa 29, 357, (452)
IBNUIBAVUNN | [e186 icib aio Gn pula ao mie ace spas aac 273
INNES As ih iis artis sel yaa teeteacesmetete ramucch repens 134
JACOBSON SUNS Geos ice are ore a 339
SJOHINSON S229 cod eee eens ePIC eee eae 406
IGEN Sia Rees rte, wee ee ne ep (244)
TERE OR Sie as. 05 ee ee Oe Eee 440
IBEVINGS iS sf Gis thei, hee ace Ree en tes ao oat ea any vege te 1
IGINDBERG 1D Ro sess es ereninenn iy ae eae eee 261, 411
IEOOMISS: Say ely wake ks are chee tee Ser aee teen 266
IMCIBEAN EI Siig ome oe ee 219, 336

MIKKELSENS DP2IMi en ee i eee 164
MITKKETS ENS) bag Sse) sian coe aan ee ene 164, 308
MOORDAN;, Picteee os sb fen ds os ee 193
MORRIS, TBs ah See Ie By)
O:FOIGHIECDIE soy 0h ee ee 72, 245
OWEN; Be 3.4 88 sola. weet be ee eee 101
PACKER; Di Bei ood eee he ae ee eee 320
PALMER ACR Gs) fo. Seas ee Shoe ee 349
PARADA): Bis). oe-c aortas cutee cre ee ae 126
PATERSON; @.Ge oo eos ee 238
PPARCE,“T. AS sey nb eee oe eee 90
RENCHASZADEH, JP. ES gee ee eee 14
PEPE,. P. Ji) foc ge tencte ol acne ee ere BID
PEPES SiMe i) haga Ae SHS)
PEREDOWS# ya coe iae eee RMR ara. allay 126
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Page numbers for book reviews are indicated by parentheses.

lV

y 7)
BS OF

VLaS J WILLIAM 4. DALE es ISSN 0042-3211

IVO //. SECTIONAL LIB
TAFE DIVISION OF bono es

VELIGER

A Quarterly published by

CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC.
Berkeley, California

R. Stohler, Founding Editor

Volume 27 July 2, 1984 Number 1

CONTENTS

Aggregation in a tropical neritid.
STEPHEN D. GARRITY AND SALLY C. LEVINGS

Establishment of mussel beds: attachment behavior and distribution of recently
settled mussels (Mytilus californianus).
JAMES H. PETERSEN

Observations on the spawn of three species of Conus from the Golfo Triste,
Venezuela.

PAB TORE AER ENCEASZAD BED oer utr tertiary on iieule tr) Aa ie foal yA 14

The rhythmic activity of Nautilus pompilius, with notes on its ecology and be-
havior in Fiji.
JLATBOIN): Js) ZZININDN It sot un tia i hon et ka ce ede aa RRO A ag ey OG cea Den ste eo MTN 19

Form and function of the radulae of pleurotomariid gastropods.
(CAR ODES Sep ltl CKIMIAN Los. idea tami en wii sesh MUNN Ral ialss ale nner UR tN atlas 29

The Pleurobranchidae (Opisthobranchia: Notaspidea) of the Marshall Islands,
central-west Pacific Ocean.
R. C. WILLAN

A new species of Gastropteron from Florida (Gastropoda: Opisthobranchia).
ALERRENCE MU GOsmiINER AND PATRICIA TvARMES (5205) 50 55.26.2200 5 54

CONTENTS — Continued

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The Veliger 27(1):1-6 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

Aggregation in a Tropical Neritid

STEPHEN D. GARRITY

Department of Zoology, University of Massachusetts,
Amherst, Massachusetts 01003

SALLY C. LEVINGS'!

Department of Zoology, University of Rhode Island,
Kingston, Rhode Island 02881

Abstract. Aggregation by the tropical intertidal mollusk Nerita scabricosta was examined. This be-
havior reduced mortality rates, especially for smaller snails. Habitat selection, size-specific differences
in movement patterns, and the physical structure of the substratum were important in the formation

and maintenance of aggregations.

INTRODUCTION

SNAILS of the genus Nerita (Archaeogastropoda) are com-
mon inhabitants of tropical hard-substratum shores. Ne-
rita scabricosta (Lamarck, 1822) inhabits the upper levels
of exposed rocky shores (GALTSOFF, 1950; HEDGPETH,
1969) from Baja California to Ecuador (KEEN, 1971).

In Panama, Nerita scabricosta (hereafter referred to as
Nerita) exists in a harsh environment (GARRITY, 1984).
Many shorelines throughout the world are covered by
macroalgae and/or sessile invertebrates (LEWIS, 1964;
STEPHENSON & STEPHENSON, 1972); these ameliorate
physical conditions during low tides by shading the rock
and/or retaining water, and can provide shelter to other
organisms. The Pacific coast of Panama is barren of mac-
roalgae (EARLE, 1972), and dense beds of mussels, bar-
nacles, or oysters are rare (GARRITY & LEVINGs, 1981;
MENGE & LUBCHENCO, 1981). Low tide temperatures on
this tropical shore can exceed 50°C (GARRITY, 1984). Fur-
ther, Nerita is more-or-less constantly exposed to terres-
trial conditions—snails move downshore behind falling
tides from resting positions above the high water mark,
then move upshore ahead of rising tides (GARRITY & LEv-
INGS, 1981).

Some mechanisms mollusks use to lessen physical stress
on this region’s rocky shores have been examined
(GARRITY, 1984). Nerita scabricosta avoids potentially le-
thal daytime conditions by (1) a limited, cyclic activity

' Address for reprint requests.

period, (2) the selective use of microhabitat, and (3) evap-
orative cooling. Here we examine the occurrence, func-
tion, and formation of multilayered aggregations in Ne-
rita, and show that this behavior enhances individual
survival. Differential movement patterns among size classes
and the structure of the preferred microhabitat result in
a typical size layering within aggregations, with smaller,
more vulnerable individuals located beneath larger snails.

METHODS

Occurrence and Numerical Composition of
Aggregations

We sampled four sites along the Pacific coast of Pan-
ama (Uva, Chitre, Taboguilla, and Naos Islands) during
the period October 1982 to April 1983. We chose sunny
days, when snails were inactive. At each site, we laid a
100-m transect tape along the shore in the splash zone.
We then walked along the tape. As snails were encoun-
tered, we recorded whether they were solitary or aggre-
gated (in contact with conspecifics), and counted the num-
ber of snails in each aggregation. We recorded whether
snails were in “exposed”? (defined as sloping, horizontal,
or vertical rock) or “protected” (defined as crevices and
tidepools) microhabitats. Protected microhabitats remain
cooler and/or wetter during daytime exposures (GARRITY,
1984, fig. 2, table 2). Because Nerita strongly prefers crev-
ices and tidepools (GARRITY, 1984), this method under-
sampled aggregations in exposed microhabitats. Transect
lines were extended laterally and additional data taken in

Page 2

exposed microhabitats until sample sizes were equal to
those from protected microhabitats.

Three-dimensional Size Structure

We examined the three-dimensional structure of four
aggregations of varying size on Culebra, Naos, and Uva
Islands during sunny days in 1979 and 1983. We dissected
aggregations layer by layer, marking the dorsal surfaces
of all visible snails with chalk, removing them, and then
repeating this on each successive layer until all were col-
lected. We measured the shell lengths of snails in each
layer with Vernier calipers.

Water Holding Capacity

Nerita scabricosta holds water extraviscerally in its non-
partitioned shell (VERMEIJ, 1978). Individuals lose water
during the day; this evaporation cools tissues significantly
(GARRITY, 1984). We tested the relationship between snail
size and the amount of free water held by removing in-
active individuals of various sizes from the rock on Naos
Island on an early morning, falling tide and quickly plac-
ing each over a funnel inserted into a small, preweighed
vial. Snails expelled water into the vials as they withdrew
into their shells. The water in each vial was weighed and
plotted against shell length.

Effects of the Number of Snails in an Aggregation

To test the hypothesis that stress decreases with increas-
ing numbers of individuals per aggregation, we set out
groups of 5; 10) 15; 205-25, 305 35, 40,45, 5057/5, 100;
125, 150, 175, 200, and 300 freshly collected Nerita on a
sloping surface on Uva Island (30 March 1983). Each
group contained small, medium, and large individuals.
Seawater was poured over each at the start of the exper-
iment. This gave all snails access to extravisceral water,
and wetted the rock so all snails could move freely within
each group. After 6 h (0900-1500) groups of snails
were collected and placed in separate mesh containers in
a 50-L cooler filled with seawater aboard the R/V Ben-
jamin. Water was changed at frequent intervals. After 24
h we examined each group and counted surviving snails.

Effects of Snail Size

To test the effect of size on susceptibility to physical
stress, we collected ~600 specimens of Nerita from Naos
Island and divided them into three groups: small (2-6 mm
shell length), medium (12-16 mm) and large (22-26 mm).
We kept snails overnight in shaded, running seawater
tanks at the Naos Marine Laboratory, and then for the
next three days (7-9 March 1983) placed subsamples of
each group, in spaced arrays, on flat rock in the high zone
of Naos Island. To prevent movement out of the spaced
arrays, snails were not watered initially (as above). After

The Veliger, Vol. 27, No. 1

yn Ww Bb OT oO N

PROPORTION OF TOTAL

U4. LLX 7 LV Ze?
—-MONOMNONMOMNONMOO
NWORFONNRONNDKROO
NO OS On ean
~— TR Nauk

—Nq WN

SNAILS / AGGREGATION
Figure 1

Distributions of aggregation sizes of Nerita scabricosta. Data are
the proportions of different size classes of aggregations encoun-
tered in 800 aggregations sampled in (A) protected and 800 in
(B) exposed microhabitats within a given range of number of
snails. See text for further information.

6 h we collected them and placed each group in laboratory
tanks. We counted the number of survivors after 24 h.

Formation of Aggregations

We observed the behavior of 50 previously marked (but
otherwise undisturbed) small, medium, and large (see
above section) snails in the field as they (1) became active
on falling tides and left aggregations to graze, (2) foraged
over wet or damp rock, and (3) became inactive either as
the rock dried or as high tide approached. We recorded
the number of snails that were active and the duration of
activity, and looked for evidence of homing or trail-follow-
ing behavior.

The role of substratum heterogeneity in the formation
of aggregations was examined in April 1983 on Naos Is-
land. We used four groups of ~200 snails (each group
encompassing the natural size range of Nerita). Snails
from each group were placed, as closely spaced but soli-
tary individuals, on (1) a flat surface (exposed microhab-

S. D. Garrity & S. C. Levings, 1984

INDIVIDUALS IN EACH LAYER

NUMBER OF

3

6 9 l2 15 18 21 24 27 30
SHELL LENGTH (mm)

Page 3

itat), (2) a flat surface with several shallow depressions
(semi-exposed), (3) a flat surface adjacent to a crevice
(protected), and (4) a flat rock adjacent to a vertical sur-
face (semi-protected). They were set out at the approxi-
mate high tide mark, on a rising tide just prior to the
normal onset of activity, and examined for evidence of
aggregation after 2 h (high tide), when movement had
ceased.

RESULTS

We pooled data on the distribution of numbers of snails
in aggregations of Nerita, because they did not differ among
sites (Chi-square tests, P > 0.1). However, differences in
the distribution of aggregation size classes between “‘ex-
posed” and “protected” microhabitats were striking (Fig-
ure 1, Chi-square test, P < 0.001). Aggregations in crev-
ices and tidepools had significantly fewer individuals
(median number = 24) than those on vertical or flat rock
(median number = 109, Mann-Whitney U test, P<
0.001). Snails aggregated in every microhabitat, but fewer
than 1% occurred as solitary individuals (n = 4) on open
surfaces compared to 16% (n = 124) in crevices and tide-
pools. It should be again noted that we did not sample all
microhabitats with equal effort and are here comparing
only the distribution of sizes of aggregations between ex-
posed and protected microhabitats.

Dissections of aggregations in the field showed differ-
ences in snail size among layers (Figure 2). Larger indi-
viduals occurred primarily in the outer layers, and in-
creasingly smaller snails formed the inner layers. This
occurred over a range (59-209 snails) of aggregation sizes
(Figure 2).

The amount of water held extraviscerally was positively
related to snail shell length (Figure 3). These data best
fit an exponential curve (y = 0.01e°'™, 7? = 0.90, n = 40),
indicating large snails hold proportionately more water
than small ones (as expected from geometric consider-
ations).

Both aggregation size and the size of individual snails
were important in reducing physical stress. First, when
groups containing different numbers of snails were set out
on Uva Island for 6 h, there was a rough inverse rela-
tionship between mortality and aggregation size (Table 1,
Spearman rank correlation coefficient = —0.97, P < 0.01).
Mortality was highest (>80%) among snails in aggrega-
tions of $25 individuals. Mortality ranged from 17-73%

Figure 2

Sizes of Nerita scabricosta in the layers of aggregations. Data are
the number of snails of a given size (shell length in mm) in each
layer from four different aggregations. A. Aggregation on a ver-
tical surface, n = 209, Uva. B. Aggregation from a crevice, n =
170, Culebra. C. Aggregation on a vertical surface, n = 134,
Culebra. D. Aggregation from a small crevice, n = 59, Naos.

Page 4 The Veliger, Vol. 27, No. 1
1.50 Table 2
S y Mortality of spaced Nerita scabricosta. Snails were placed
o Game? in spaced arrays on flat rocks for 6 h during low tide.
= 1.20 om They were then placed in running, shaded seawater and
Wd ee survivors counted after 24 h.
x< e
W 90 cone Large Medium Small
m ae 7 (22-26 mm) (12-16 mm) (2-6 mm)
E eee N N N N N N
= 60 tested died tested died tested died
5 eu Day 1 46 4 51 34 55 51
e merece Day2 75 5 75 29 75 58
= 30 .° Day 3 U5) 7 WS al YS 70
FAT ° Total 196 16 201 114 205 183
= 5 2 Proportion dead _.08 Bi 89
O
Frese Vereen Perennial rer] ‘ tae : fee, 1
OS) Ge Stila Shula eolneae7eso ae a a all eee i, a a
snails died than medium ones (8% vs. @ overall, Chi-
ier EENGTH (mmi) square test, P < 0.001), and significantly fewer medium-
Figure 3 sized snails died than small Nerita (57% vs. 89% overall,

Amount of water held within the shell vs. shell length. Regres-
sion equation is: y = 0.01e°'**, 7? = 0.90. See text for further
explanation.

in aggregations of up to 100 snails. Only groups of 125
or more experienced less than 10% mortality, and there
were two deaths in the largest (n = 300) group. Second,
snails set out as solitary individuals on Naos Island showed
size-dependent differences in mortality rates (Table 2).

Table 1

Mortality of Nerzta scabricosta in artificially constructed

clumps. Clumps were constructed on Uva Island and set

out for 6 h during low tide. Snails were placed in mesh

containers in frequently-changed seawater and survivors
counted after 24 h.

Aggregation Number Percent mortality
size dead after 24 h
5 4 80
10 9 90
15 13 87
20 Lie 85
25 21 84
30 22 73
35 19 54
40 18 45
45 20 44
50 23 46
us 22 29
100 9 17
125 8 6
150 6 4
175 3 2
200 4 2
300 2 1

Chi-square test, P < 0.001). Some mortality in these ex-
periments may have resulted from handling; however, all
snails were handled in the same way. High rates of mor-
tality do not reflect events in nature. Snails were set out
in flat or sloping homogeneous rock (very exposed micro-
habitat) to facilitate comparisons among treatments.
Observations of marked individuals in the field showed
shell size was an important variable in patterns of move-
ment (Table 3). During the tidal cycle, more large snails

Table 3

Movement patterns for differently-sized Nerita scabricosta.

A. Percent movement.!

Time

Snail High Low High

size tide +2h +4h tide +8h +10h tide
Small 0 11 0 0 0) 8 0
Medium 0) 47 12 3 1 16 0
Large 0 64 35 9 14 51 1
B. Distance moved.?

Snail

size Median Range Probability
Small 0.1 m 0.03-0.48
Medium 1.3m 0.06-4.14 San
Large 3.62 m 0.05-6.70 j

' Percent of 50 snails in each size class active at a given time
over a complete tidal cycle (12 h). Small snails = 2-6 mm, me-
dium snails = 12-16 mm, large snails = 22-26 mm.

? Distance moved from resting position, measured as outward
path for the same snails as in (A); size classes as in (A). Prob-
abilities are from comparisons of the distance moved by small
and medium, and medium and large snails, using Mann-Whit-
ney U tests.

S. D. Garrity & S. C. Levings, 1984

became active than medium snails (Sign test, P = 0.031)
and more medium snails were active than small ones (P =
0.016). A similar gradient appeared in the distances that
differently sized, active individuals moved (Table 3B); the
median distance moved by large snails (3.6 m) was sig-
nificantly greater than that by medium snails (1.3 m), and
the latter was significantly greater than for small snails
(0.1 m, Mann-Whitney U tests, P < 0.001, both cases).

Snails of all sizes moved as the tide fell, but small snails
were active for <0.5 h and moved back into crevices and
aggregations as the rock dried. Seventeen of 50 medium
and 38 of 50 large individuals moved downshore with the
tide, rather than moving back. Larger snails sometimes
followed visible trails left by conspecifics when moving up
or downshore (n = 23/108), but seldom did so when graz-
ing at lower levels (n = 5/87). Individuals did not always
move back to the same aggregation or position. Over a
five-day period, 33 of 50 large, marked snails dispersed
to several other aggregations within 5 m of the original
one. Net lateral movement along the shore is usually slow,
except in the presence of the predaceous gastropod Pur-
pura pansa (GARRITY & LEVINGS, 1981).

The nature of the substratum plays a role in the for-
mation and structure of aggregations. Of the specimens of
Nerita (n = 200) placed upon a flat, homogeneous surface,
127 remained solitary, and all aggregations had a single
layer. The second group of 200 clustered around depres-
sions present on the rock; again there were no multilay-
ered groups and 58 snails remained solitary. Snails placed
adjacent to a crevice all (n = 201) moved into it. Within
the crevice, 26 were solitary and the rest in multilayered
aggregations. Finally, Nerita placed adjacent to a vertical
surface moved either to the angle formed by the intersec-
tion of the two surfaces where they formed a large (n =
185), multilayered aggregation, or onto the vertical sur-
face (n = 12 aggregated in a single layer, 3 solitary).

DISCUSSION

Aggregation in limpets (review in BRANCH, 1981) and
other herbivorous gastropods (ROHDE & SANDLAND, 1975;
VANNINI & CHELAZZI, 1978, and included references) has
been related to abiotic factors such as desiccation, wave
action, or insolation, although the causes of this behavior
have not been shown. Considerable evidence supports the
notion that aggregation is an important mechanism to re-
duce physical stress in Nerita scabricosta. First, in natural
situations, both the occurrence of snails in aggregations
and the number of individuals per group were greatest in
harsher microhabitats (Figure 1). Even in more benign
microhabitats, the majority (84%) aggregated. Mean tis-
sue temperatures of snails in aggregations stay signifi-
cantly lower than those of solitary ones throughout the
day, both on open rock and in crevices (GARRITY, 1984,
fig. 11), and the mortality rate of aggregated snails is
lower than that of solitary ones (GARRITY, 1984, table 5).
Field manipulations of aggregation size in an exposed mi-

Page 5

crohabitat showed members of larger groups survived bet-
ter than Nerita in small ones (Table 1).

Most aggregations consisted of two or more layers and
had a distinct size structure; larger individuals occurred
chiefly in the top layer and the proportion of smaller snails
increased with depth (Figure 2). The smallest size classes
were never represented in the top layer. This size struc-
ture may have chiefly benefited small Nerita, because they
held proportionately less water (Figure 3) and were most
vulnerable to stress (Table 2). Snails in the interior of
aggregations were both shaded and dampened by those
above; it also is likely, given the movement pattern of
small Nerita (Table 3B), that water trickled by larger
snails in aggregations was a source of extravisceral water
for small ones in bottom layers. Although water lost by
solitary snails decreases with size, larger individuals in
aggregations lose proportionately more water than small
ones (GARRITY, 1984, fig. 12).

The formation and maintenance of aggregations had
several components. Perhaps most importantly, Nerita
chose crevices and tidepools, comprising <20% of the rock
surface in the splash zone (GARRITY, 1984, fig. 1), and
avoided more exposed areas of the rock during periods of
inactivity (LEVINGS & GARRITY, 1983, table 3). This be-
havior gave inactive Nerita a clumped distribution in space.
Second, size-specific activity patterns tended to maintain
aggregations and could result in snails being layered by
size: small individuals moved short distances and were
active only briefly before returning to aggregation sites
(Table 3). As shell size increased, so did foraging time
and distance (Table 3; also see LEVINGS & GARRITY, 1983,
fig. 2). Larger snails moved into aggregations last, and
thus occurred in the outer layers. The nature of the sub-
stratum may enhance this effect. Crevices, the most pre-
ferred microhabitat, are wider at the mouth than at the
bottom. Larger snails were thus excluded from bottom
layers (see also RAFFAELLI & HUGHES, 1978). Small crev-
ices, pocks, or depressions are probably foci for aggrega-
tions found on horizontal or sloping surfaces. The occur-
rence of these microsites in nature was not monitored in
our transects. However, when groups of 200 spaced snails
were placed (a) on flat, homogeneous rock and (b) on a
flat surface containing several small depressions, more of
the second group aggregated, and aggregations centered
on the depressions. Lastly, larger Nerita moved up- and
downshore as a wave front immediately behind falling
tides and ahead of rising tides (GARRITY & LEVINGS, 1981).
During this vertical movement, individuals frequently fol-
lowed slime trails of leading snails. These two behaviors
resulted in a clumped distribution when Nerzta moved to
or from refugia.

Nerita scabricosta actively avoids submergence. This re-
duces exposure to predaceous fishes (BERTNESS ef al., 1981),
but results in increased exposure to potentially lethal con-
ditions during the day. Behavioral mechanisms used by
Nerita to reduce desiccation and thermal stress include a
reduced activity period, microhabitat selection, and evap-

Page 6

orative cooling. These mechanisms are enhanced by the
formation of multilayered aggregations of up to several
hundred snails, resulting from size-specific differences in
behavior and activity patterns, and by the physical struc-
ture of preferred microhabitats. Aggregation is an impor-
tant mechanism, especially for smaller Nerita, for the re-
duction of stress on this harsh tropical shore.

ACKNOWLEDGMENTS

J. Cubit, M. Denny, D. R. Robertson, and V. Vergel of
the Naos Marine Laboratory were particularly helpful
with discussions and support. J. Bryan and L. Cruz ran
the R/V Benjamin on several memorable cruises. Finan-
cial support from the Lerner-Gray Fund, Sigma Xi, the
Smithsonian Institution, and the Smithsonian Tropical
Research Institute made the research possible. Criticism
from P. Frank, D. W. Phillips and an anonymous review-
er improved the manuscript.

LITERATURE CITED

BERTNESS, M. D., S. D. Garrity & S. C. LEvinGs. 1981.
Predation pressure and gastropod foraging: a temperate-
tropical comparison. Evolution 35:995-1007.

BrancH, G.M. 1981. The biology of limpets: physical factors,
energy flow, and ecological interactions. Oceanogr. Mar.
Biol. Ann. Rev. 19:235-380.

EARLE, S. A. 1972. A review of the marine plants of Panama.
Bull. Biol. Soc. Wash. 2:69-87.

GaLTsorFF, P.S. 1950. The pearl oyster resources of Panama.
U.S. Fish Wildlife Serv., Spec. Sci. Rep. Fish. 28:21-52.

The Veliger, Vol: 27,.Nom

Garrity, S. D. 1984. Some adaptations of gastropods to phys-
ical stress on a tropical rocky shore. Ecology 59:559-574.

Garrity, S. D. & S. C. Levincs. 1981. A predator-prey in-
teraction between two physically and biologically con-
strained tropical rocky shore gastropods: direct, indirect and
community effects. Ecol. Monogr. 51(3):267-286.

HEDGPETH, J. W. 1969. An intertidal reconnaissance of rocky
shores of the Galapagos. Wasmann J. Biol. 27:1-24.

KEEN, A. M. 1971. Seashells of tropical West America. Stan-
ford Univ. Press: Palo Alto. 1064 pp.

Levincs, S. C. & S. D. Garrity. 1983. Diel and tidal move-
ment of two co-occurring neritid snails: differences in graz-
ing patterns on a tropical rocky shore. J. Exp. Mar. Biol.
Ecol. 67:261-278.

Lewis, J. R. 1964. The ecology of rocky shores. Hodder and
Stoughton: London. 323 pp.

MENGE, B. A. & J. LUBCHENCO. 1981. Community organi-
zation in temperate and tropical rocky intertidal habitats:
prey refuges in relation to consumer pressure gradients. Ecol.
Monogr. 51(4):429-450.

RAFFAELLI, D. C. & R. N. HUGHES. 1978. The effects of
crevice size and availability on populations of Littorina rudis
and Littorina neritoides. J. Anim. Ecol. 47:71-83.

RouDE, K. & R. SANDLAND. 1975. Factors influencing clus-
tering in the intertidal snail Cerithium moniliferum. Mar.
Biol. 30:203-215.

STEPHENSON, T. A. & A. STEPHENSON. 1972. Life between
tidemarks on rocky shores. Freeman: San Francisco. 425

PP-

VANNINI, M. & G. CHELAZZI. 1978. Field observations on the
rhythmic behaviour of Nerita textilis. Mar. Biol. 45:113-
121.

VERMEI, G. J. 1978. Biogeography and adaptation. Harvard
Univ. Press: Cambridge. 332 pp.

The Veliger 27(1):7-13 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

Establishment of Mussel Beds: Attachment

Behavior and Distribution of Recently
Settled Mussels (Mytilus californianus)

JAMES H. PETERSEN!

Department of Biology, University of Oregon,
Eugene, Oregon 97403

Abstract. The distribution and behavior of small Mytilus californianus (plantigrades) were studied,
and results were interpreted with respect to intertidal community structure and establishment of mussel
beds. Mytilus californianus plantigrades were found on mussel beds, algae, and bare rock. Highest
densities of plantigrades were observed on the red alga Endocladia muricata. Field experiments and
sample data suggest that algae that grow upon adult mussel shells have no effect on the density of
settlers or plantigrades in a patch of mussels. Plantigrades were abundant in established mussel beds
throughout the year because settlement is continuous. Laboratory choice experiments indicate M. cal-
ifornianus plantigrades do not select particular species for byssal attachment. Mytilus californianus beds
are established only after a surface has been previously colonized. By settling and surviving upon many
different surfaces, M. californianus is capable of establishing populations throughout a broad geographic

range.

INTRODUCTION

PAST ECOLOGICAL work on the marine mussel Mytilus
californianus Conrad, 1837, has emphasized population
regulation (PAINE, 1966, 1974; ACKERMAN, 1971), com-
petition with other sessile species (PAINE, 1966, 1974;
HARGER, 1968, 1970a, b, 1972a, b; SUCHANEK, 1981),
infaunal communities (HEWATT, 1935; KANTER, 1977;
SUCHANEK, 1979), and the role of mussel beds in com-
munity structure (LEVIN & PAINE, 1974; PAINE & LEVIN,
1981). These studies have demonstrated that M. califor-
nianus is an important species in the intertidal community
because of the competitive ability, persistence, and abun-
dance of individuals and populations (mussel beds). How-
ever, relatively little work has been done on the attach-
ment preferences and survival patterns of small M.
californianus. Because adult distribution and abundance
patterns are the result of small mussel behavior and sur-
vivorship, work on these topics should improve our un-
derstanding of intertidal community dynamics and pop-
ulation development of M. californianus.

PETRAITIS (1978) compared the distributions of juvenile

' Present address: Natural History Museum of Los Angeles
County, 900 Exposition Blvd., Los Angeles, CA 90007.

Mytilus californianus and M. edulis Linnaeus, 1758, in
southern California and concluded that juveniles were more
likely to be associated with conspecific adults than adults
of the other species. He attributed these distributions to
selective settlement (primary settlement) rather than
movement of plantigrades (secondary settlement) or ju-
venile mortality. PAINE (1974) sampled algae, barnacles,
and mussel beds in Washington and noted high densities
of small mussels (less than 1.5 cm) among “‘filamentous”
algae and the byssal threads of adult mussels.

This study presents data on the behavior and distri-
bution of small, post-settlement Mytilus californianus. Spe-
cific emphasis is given to the distribution, abundance, and
attachment behavior of plantigrades (individuals between
1.0 and 10.0 mm in length). Observed patterns are inter-
preted with respect to mussel bed establishment and local
community structure. Data on primary settlement pat-
terns and pediveliger behavior of M. californianus are pre-
sented elsewhere (PETERSEN, 1984).

DISTRIBUTION anp DENSITY or
PLANTIGRADES

The major study site was Mussel Reef on Yoakam Point,
Oregon (43°20'N; 124°22’W). Mussel Reef is a flat, wave-
cut platform about 2.0 m above mean lower low water.

Page 8

Table 1

Density of Mytilus californianus plantigrades on various

substrata at Mussel Reef, Oregon. Mean number of plan-

tigrades is given per 100 cm? of substratum. Samples were
collected in May and June of 1980.

Substratum Mean SD n
Endocladia muricata 260.0 174.5 10
Gigartina papillata 125.0 128.8 5
Cladophora sp. 95.8 137.0 18
Corallina vancouverensis

Yendo, 1902 79.3 82.8 6
Rhodomela larix 62.4 37.6 8
Analipus japonicus (Harvey)

Wynne, 1971 40.0 3355 5
Unclassified red alga #1 27.0 29.0 12
Mytilus californianus 21.6 9.1 8
Polysiphonia sp. 10.3 18.3 DD,

Bare-barnacle 0.0 0.0 9

Mussel beds of Mytilus californianus and patches of the
red alga Rhodomela larix (Turner) C. Agardh, 1822, cover
most of this sandstone platform (PETERSEN, 1983).

The abundance of plantigrades on several substrata was
estimated at Mussel Reef. Pseudo-random points were
established by blindly throwing an object onto mussel beds,
algal dominated areas, or “bare-barnacle” patches. Bare
rock areas usually included many small barnacles (pri-
marily Balanus glandula Darwin, 1854, and Chthamalus
dalli Pilsbry, 1916) so this substratum will be referred to
as bare-barnacle. Samples were collected at a pseudo-ran-
dom point, or as near one of these points as possible.
Mytilus californianus beds were sampled by collecting all
mussels, infauna, and sediment in a 100-cm? area. Rho-
domela larix (25-cm* samples) and other substrata (4-cm?
samples) were sampled by scraping all material in the
given area into a plastic bag. Samples were returned to
the laboratory and visually or mechanically sorted (PE-
TERSEN, 1983). All mussels less than 10 mm in length
were measured to the nearest 0.1 mm with an ocular mi-
crometer; larger mussels were measured with vernier cal-
ipers.

Small Mytilus edulis, which were occasionally found at
the study site (PETERSEN, 1983), and M. californianus are
morphologically similar, and separation of plantigrades of
these species is difficult (SUCHANEK, 1978; personal ob-
servation). To develop an identification criterion, M. ed-
ulis collected in Coos Bay, Oregon, and Spanish Ship Bay,
Nova Scotia (supplied by Dr. Gary Newkirk), were com-
pared with M. californianus of similar size from Mussel
Reef. Individuals greater than 1.0 mm in length differed
in the shape of the ventral shell margin immediately pos-
terior to the umbo. The ventral margin of M. edulis valves
is straight or slightly convex from the umbo to the pos-
terior part of the shell where the margin bends dorsally.
However, the ventral shell margin of M. californianus

The Veliger, Voli Z27-3Noml

Table 2

Mean percent cover on shells of Mytilus californianus from
established mussel beds at Mussel Reef, Oregon. Samples
(n = 74) were collected between June 1979 and Septem-

ber 1981.

Substratum Mean (%) SD
Bare shell 86.8 V2
Barnacles 8.8 Dei
Cladophora sp. 1e3 3.6
Polysiphonia sp. 1.1 2.4
Rhodomela larix 0.7 2.9
Endocladia muricata 0.4 115)
Fucus distichus Linnaeus, 1767 0.3 1.6
Spirorbis borealis Daudin, 1800 0.2 0.5
Anthopleura elegantissima

(Brandt, 1835) 0.1 0.3
Corallina vancouverensis 0.1 0.4
Odonthallia floccosa (Esper)

Falkenberg, 1901 0.1 0.5
Haliclona sp. 0.1 0.5
Gigartina papillata <0.1
Ulva lactuca Linnaeus, 1753 <0.1
Gelidium sp. <0.1
Halichondria sp. <0.1
All algae 3) 7.4

plantigrades usually has a small, gentle indentation im-
mediately posterior to the umbo region. Identification of
plantigrades was based upon this characteristic of the shell.
Mussels less than 1.0 mm in length could not be easily
identified to species, so these individuals are referred to
as “settlers.”

Small mussels were found on all substrata sampled,
except the bare-barnacle surface (Table 1). Density was
highest on the red alga Endocladia muricata (Postels &
Ruprecht) J. Agardh, 1847, with 260.0 plantigrades/100
cm? of alga. Other algae had plantigrade densities between
125.0/100 cm? on Gigartina papillata (C. Agardh) J.
Agardh, 1846, and 10.3/100 cm? on Polysiphonia sp. The
density of plantigrades in Mytilus californianus beds (21.6
plantigrades/100 cm?) was relatively low compared to other
substrata sampled.

The high variability of these data probably indicates a
true patchy distribution of plantigrades and not just a
sampling problem. All algal and bare-barnacle samples,
except Rhodomela larix, were 4 cm?. Because many of the
algae sampled occur as small patches, increasing sample
size to improve the estimates was not possible. Moreover,
the data from R. larix samples were also highly variable,
although sample size was 25 cm? for this species. Increas-
ing the number of samples of a substratum did not seem
to improve the estimates; for example, the variation in
Polysiphonia sp. (n = 22; coefficient of variation = 178%)
was greater than for those substrata where fewer samples
were taken.

J. H. Petersen, 1984

Page 9

JJASONDJSFMANMJSIJSASOND JS FMAMYJ JS AS

1979

1980 1981

Time
Figure 1

Density of Mytilus californianus plantigrades in M. californianus beds at Mussel Reef, Oregon. Each point is the
mean number of plantigrades per 100 cm? of substratum. Most means are the average of four samples.

Plantigrades of M. californianus were present in estab-
lished mussel beds throughout the sampling period (Fig-
ure 1). Plantigrade density in M. californianus samples
followed roughly the same seasonal pattern as settlement
density (PETERSEN, 1984): high numbers of settlers and
plantigrades in late summer through fall and lower num-
bers during other parts of the year. Plantigrade density
increased in the fall of 1980, corresponding to heavy larval
settlement beginning in June 1980 and peaking in August
1980 (PETERSEN, 1984; see also KELLEY et al., 1982). These
summer settlers likely grew into the plantigrade category
by fall, causing the increase shown in Figure 1.

ROLE or ALGAE on ADULT
MUSSEL SHELLS

Several species of algae occur on mussel shells from the
central Oregon coast (Table 2). The average cover of algae
in all samples was about 4%, whereas the maximum cover
was 30% in a sample collected in October 1980. The vari-
ation in total algal cover between samples was large be-
cause species were patchily distributed over the reef; some
areas had a relatively heavy cover of algae and barnacles
while in other areas the mussel shells were quite bare.
SUCHANEK (1979) investigated the role of herbivores in
mussel beds. When grazers (limpets and littorines, pri-
marily) were removed from a patch of mussels, the percent
cover of algae increased dramatically. Many herbivores
were found in the samples collected at Mussel Reef, and
they may be controlling the overall abundance of algae.
These grazers may also be responsible for the patchy dis-

tribution of algal species on the mussel beds, if the density
of herbivores is uneven across the reef. There were no
obvious seasonal patterns in total algal abundance on
mussel shells; however, annual species of algae were more
abundant at certain times of the year, especially during
the spring and summer.

Algae on shells in established mussel beds could affect
the recruitment of settlers and plantigrades into the bed
in several ways. As a settling larva swims and drifts
through the water, it may encounter an algal thallus and
begin testing this thallus or the nearby surfaces for their
attachment suitability. The larva might attach to the alga
itself or it might use the alga as a track to crawl to a more
suitable substratum. Algal patches also increase the total
exposed surface area of a mussel bed, thus increasing the
chance that planktonic larvae will encounter a surface and
settle in this area. If the alga has erect thalli, they may
function as a net, filtering water moved by waves, tides,
and currents.

To test the hypothesis that algae or barnacles on mus-
sels increase larval settlement, or recruitment of planti-
grades in the mussel bed, a removal experiment was car-
ried out at Mussel Reef. In March 1980, five 400-cm?
areas were haphazardly selected within the established
mussel bed. In each of the five patches, at least 10% of
the exposed shell was initially covered by algae. All of the
algae and barnacles were scraped from the mussels in each
area with a putty knife and a wire brush (Removal treat-
ment). These five sites were scraped monthly to remove
any algae or barnacles that settled on the mussel shells.
After 12 months, 100-cm? samples were collected from the

Page 10

The Veliger;. Voli2Z7eeiona

Table 3

Density of settlers and Mytilus californianus plantigrades
in algal removal experiments. Mean number of individ-
uals, with SD, is given per 100 cm? of substratum. All
data were collected in April 1981. Only those settlers and
plantigrades that were attached by byssal threads to adult
mussels were included in calculating these means; unat-
tached and algal attached mussels were not included be-
cause this is a test of recruitment zmto the mussel matrix.
See text for an explanation of controls.

Treatment Mean SD n F

Settlers

Removal 6.5 5.0 4

High % algae control 4.5 6:4 2 0.17 NS

Low % algae control 5.0 2.8 2
Mytilus californianus plantigrades

Removal 38.5 PANS) 4

High % algae control 3215) 38.9) 28 O:G0RN'S

Low % algae control 14.0 12.7 2

NS = Not significant.

center of each 400-cm? removal area. One of the five orig-
inal sites was damaged by winter waves, so only four
samples of scraped mussels were collected. Two types of
control samples were collected at the same time as the
Removal samples: (1) samples that had more than 10%
algal cover on the mussel shells (High % Algae Control),
and (2) samples that had less than 1% algal cover on the
mussels (Low % Algae Control). All samples were re-
turned to the laboratory and processed in the usual fash-
ion.

Data from the algal removal experiments suggest that
settlement and plantigrade recruitment were not signifi-
cantly affected by algae on adult mussel shells (Table 3).
Settler densities were similar in all treatments and were
not significantly different. Densities of plantigrades ranged
from 38.5/100 cm? in the Removal treatment to 14.0/100
cm? in the Low % Algae Control; there was no statistical
difference between treatments. Because variation in both
controls and removals was high, a “significant”? decrease
in the removal series may have been difficult to detect.
The relatively high densities of settlers and plantigrades
in the Removal treatment, however, suggest there was no
effect of removing algae from the adult shells.

Mussel samples collected between June 1980 and Jan-
uary 1981 were also used to test the effects of algal cover.
During this period, settlement intensity was fairly con-
stant at Mussel Reef (PETERSEN, 1984). The number of
settlers in a sample was not related to the total percent
algal cover in that sample (P > 0.05, 7? = 0.26, n = 22).
Also, the number of Mytilus californianus plantigrades and
the total percent algal cover were unrelated (P > 0.10,
r? = 0.09, n = 22). This correlative evidence and the re-
moval experiment suggest that the presence of algae on

Table 4

Results of four-way choice experiments with Mytilus cal-

ifornianus plantigrades. E is the expected number of plan-

tigrades attached to a substratum based on the encounter

rate for that substratum. O is the observed number of
attached plantigrades.

Bound-
ary
Substratum (mm) O E x?

Trial #1
M. californianus 384 14 16.9
M. edulis 425 28 18.7 Nile
Rhodomela larix 427 8 18.8
Sandstone 331 19 14.6

Trial #2
M. californianus 403 op)’ 17.8
M. edulis 431 14 19.0 8.5*
Rhodomela larix 384 25 16.9
Sandstone 323 7 14.3

*= P< 0.05.

adult mussels does not significantly increase (or decrease)
settlement or recruitment into the mussel bed.

PLANTIGRADE SELECTION
EXPERIMENTS

The attachment preferences of Mytilus californianus plan-
tigrades were investigated in the laboratory with four-way
and two-way choice experiments. The four-way choice
experiments were run in 30 X 60 cm glass aquaria. Myt-
ilus californianus adults, M. edulis adults, Rhodomela larix
thalli, and pieces of bare sandstone were the substrata
tested. To make the encounter probabilities of the sub-
strata approximately equal, and to avoid confounding ef-
fects of aquarium edges, each substratum was placed in a
separate corner of the aquarium, and the inner boundary
of a substratum was extended from the midpoint of one
side of the aquarium to the midpoint of the adjacent side.
This arrangement produced in the aquarium a diamond-
shaped arena, the sides of which were the four test
substrata. A searching plantigrade in this arena would
encounter only the four test substrata and none of the
aquarium edges. The expected encounter rate of a sub-
stratum was estimated by tracing the boundary of the
substratum on paper, measuring the length of this bound-
ary with an opisometer (a map distance-measurement in-
strument), and calculating what proportion of the total
boundary length was attributable to this substratum.

All test substrata and plantigrades were collected from
Mussel Reef. Mussels, algae, and sandstone were rinsed,
and all animals and algae were removed using a dissecting
microscope. Test substrata were placed in an aquarium,
water was added, and the setup was left for 24 h before
100 naive Mytilus californianus plantigrades were haphaz-

J. H. Petersen, 1984

ardly placed in the central arena. Plantigrades were al-
lowed to search and attach for 24 h, after which the sub-
strata were collected and the number of attached
plantigrades was determined. During the search period,
aquaria were kept in dim, diffuse light and aeration was
provided. Two trials of these four-way choice experiments
were run.

Table 4 lists the data and analyses of the four-way
choice experiments. In the first trial, of those plantigrades
that chose a substratum, Mytilus edulis adults were pre-
ferred (40.6% of all attached individuals). Only eight
plantigrades chose Rhodomela larix thalli, much less than
the 18.8 expected based upon the encounter probabilities.
The number of plantigrades attached to sandstone and M.
californianus were near the expected values. The results of
the second trial differed somewhat from the first trial.
Rhodomela larix was the preferred substratum (36.8% of
all attached individuals) and sandstone was least preferred
(10.3%). In both experiments, about one-third of the plan-
tigrades tested were found unattached or attached to the
glass in the central arena. Although both trials differed
significantly from random attachment based upon the cal-
culated encounter probabilities, the different results in the
two trials and the high proportion of glass-attached in-
dividuals suggest that M. californianus plantigrades may
not “prefer” any of these substrata over others.

Different results in the four-way experiments could also
result from inadequate control of experimental factors;
therefore, a second plantigrade attachment experiment was
run. Mytilus edulis, M. californianus, and Rhodomela larix
were used as test substrata in two-way choice experiments
(Table 5). Each test substratum was distributed in a semi-
circle around the edge of a 2-L finger bowl, and 30 plan-
tigrades were added to the central area of the bowl. Plan-
tigrades were allowed to search and attach for 12 h before
the substrata were removed and examined. Boundaries of
the substrata were not measured in these experiments;
encounter probabilities of the two test substrata were as-
sumed to be equal. Each experiment was replicated. The
distribution of plantigrades was not significantly different
from random attachment expectation in any of these ex-
periments. About half (87/180) of the plantigrades used
in these experiments were unattached or attached to the
glass finger bowl. The conclusions from these experiments
are similar to those obtained from the four-way choice
experiments: none of the substrata tested appear to be
strongly preferred by M. californianus plantigrades.

DISCUSSION

Some marine mussels, particularly Mytilus edulis studied
in Europe, go through two attachment phases called pri-
mary settlement and secondary settlement (BAYNE, 1964,
1976; SEED, 1969). As larvae settle from the plankton,
they test various substrata and select a primary attach-
ment site (primary settlement). Primary settlement is often
on a filamentous alga (BAYNE, 1964; PAINE, 1974; PE-

Page 11

Table 5

Results of two-way choice experiments with Mytilus cal-
ifornianus plantigrades. E is the expected number of in-
dividuals attached to this substratum based on the as-
sumption of equal encounter probabilities. O is the
observed number of attached plantigrades.

Substratum O E x?
Mytilus edulis 5 6.0 0.1 NS
Rhodomela larix Th 6.0
Mytilus edulis 12 8.5 2.1 NS
Rhodomela larix 5 8.5
Mytilus californianus 9 8.5 0.0 NS
Rhodomela larix 8 8.5
Mytilus californianus 5 5) 3.4 NS
Rhodomela larix 14 95
Mytilus californianus if 6.5 0.0 NS
Mytilus edulis 6 6.5
Mytilus californianus 4 HES 2.4 NS
Mytilus edulis 11 7.5

NS = Not significant.

TERSEN, 1984). Secondary settlement is movement and
reattachment of small mussels, usually when individuals
are greater than 1.0 mm (BAYNE, 1964). Movement is
often onto an established mussel bed (BAYNE, 1964). BAYNE
(1964) suggested this behavior reduces competition be-
tween juvenile and adult M. edulis. Whether M. edulis has
similar behavior on American shores is not known
(SUCHANEK, 1978).

Studies on settlement and distribution of small Mytilus
californianus, including this paper, have not demonstrated
secondary settlement behavior in this species (PAINE, 1974;
PETRAITIS, 1978; SUCHANEK, 1981; PETERSEN,1983). In
laboratory choice experiments, M. californianus larvae
preferred adult clumps of M. edulis (PETERSEN, 1984). In
field samples, M. californianus has been found on a variety
of substrata, particularly filamentous algae and byssal
threads of adult mussels (PAINE, 1974; SUCHANEK, 1979;
PETERSEN, 1984). These results suggest that M. califor-
nianus settles broadly if its preferred substratum, M. ed-
ulis, is unavailable. In areas where M. edulis patches are
common, M. californianus may select these patches over
other available substrata; however, more work needs to be
done on settlement preferences in the field.

Mytilus californianus settlers survive to the plantigrade
stage on a variety of substrata. Only bare rock and bar-
nacle-covered rock were barren of M. californianus plan-
tigrades, although densities were fairly low in some patches
of algae, such as Polysiphonia sp. Some surface cover is
apparently necessary for larval settlement and plantigrade
attachment.

Algal and mussel patches undoubtedly have many crev-
ices and holes where plantigrades can attach and receive
some protection from wave battering and predators. Plan-

Page 12

The Veliger; Volk Zier

tigrades are often found in the axils of thalli, in the crevice
between adult mussel valves, and in cracks in rocks. Such
microhabitats offer physical protection, and plantigrades
may also be more secure when their byssal threads are
attached to many different surfaces, rather than just one
flat surface.

Differential predation rates might also explain the dis-
tribution of plantigrades. Many animals, including sea-
stars, gastropods, crabs, and birds, are known to prey
upon mussels (e.g., NORTON-GRIFFITHS, 1967; HARGER,
1972b; PAINE, 1974; SEED, 1976).

Some shore birds—e.g., Surf Birds, Aphiza virgata
(Gmelin), and Black Turnstones, Arenaria melanocephala
(Vigors)—prey upon small mussels along the central Or-
egon coast, eating both Mytilus californianus and M. edulis
(Chris Marsh, personal communication). Searching by
these birds may be more efficient on bare and barnacle-
covered rock surfaces, leading to complete removal of all
recent settlers and plantigrades. Predation in algal patches
could be less efficient because some plantigrades might be
overlooked by the birds and thus survive. Nucella emar-
ginata (Deshayes, 1839) is an important gastropod pred-
ator on large mussels, particularly M. edulis (PARIS, 1960;
DayTOoNn, 1971; HARGER, 1972b; SUCHANEK, 1978), but
no studies have concentrated on the effects of this snail on
plantigrades. Many small mussel shells with gastropod
bore holes were found in the samples of algae and mussels
collected at Mussel Reef. Plantigrades are undoubtedly
eaten by these gastropods although the intensity of pre-
dation in different patches is unknown. Nucella exclosure
experiments were attempted but were unsuccessful be-
cause of severe weather and vandalism. The role of other
predators in controlling the abundance and distribution of
small M. californianus has not been investigated although
there has been speculation on this subject (SUCHANEK,
1979).

The primary settlement behavior (PETERSEN, 1984) and
plantigrade survival patterns of Mytilus californianus may
help to explain how mussel beds are established and per-
sist through a broad geographic range. Mytilus californi-
anus forms extensive beds on exposed rocky shores from
Mexico to British Columbia (SooT-RYEN, 1955;
SUCHANEK, 1981). Disturbances occur periodically within
this range, removing patches of established mussel beds
(DayTON, 1971; personal observation). Succession within
cleared areas culminates in new M. californianus beds which
persist until another disturbance occurs. In Washington,
patches are filled by algae, M. edulis, and finally M. cal-
ifornianus, which settles among M. edulis patches and
eventually excludes this competitively inferior mussel
(PAINE, 1974; PAINE & LEVIN, 1981). However, because
M. edulis is not very common on central Oregon shores
(PETERSEN, 1983), and perhaps in other local areas, the
recovery pattern may be somewhat different.

If Mytilus edulis patches were required for M. califor-
nianus colonization, the sequence leading to mussel bed
recovery would be incomplete in geographic areas where

M. edulis is sparse. However, M. californianus larvae begin
to settle once a disturbed area has been colonized by algae.
Continual reproduction and broad larval preferences en-
sure that some settlement will occur on various algae.
Pediveligers attach to many surfaces (PETERSEN, 1984)
and plantigrades survive on most substrata, particularly
those with small holes and crevices. This general attach-
ment behavior of M. californianus pediveligers and their
survival on diverse substrata assure a broad distribution
of growing mussels in the disturbed area. As plantigrades
grow, they gradually fill the original disturbed patch, at-
tach to the rock, and exclude other species (PAINE & LE-
VIN, 1981). The dynamics of patch recovery may be al-
tered because the survivorship rate of M. californianus is
probably different in algal patches than in M. edulis
patches, but the mechanism for mussel bed recovery re-
mains intact.

ACKNOWLEDGMENTS

Several people provided useful comments and criticism
during this work and I thank them all: Peter Frank, Jane
Lubchenco, Chris Marsh, Fred Munz, Bayard Mc-
Connaughey, Robert Paine, Tom Polacheck, Dan Udovic,
and an anonymous reviewer. Gary Newkirk kindly sup-
plied some small mussels from Nova Scotia. My wife,
Tyan, provided continual help and encouragement for
which I am very thankful. This research was supported
by grants from the Department of Biology, University of
Oregon, and Sigma Xi.

LITERATURE CITED

ACKERMAN, J. M. 1971. The demography of the marine mus-
sel, Mytilus californianus. Doctoral Thesis, University of
California, Berkeley.

Bayne, B. L. 1964. Primary and secondary settlement in M.
edulis L. (Mollusca). J. Anim. Ecol. 33:513-523.

BayNE, B. L. 1976. The biology of mussel larvae. Pp. 81-120.
In: B. L. Bayne (ed.), Marine mussels: their ecology and
physiology. Cambridge University Press: Cambridge.

DayTon, P. K. 1971. Competition, disturbance, and commu-
nity organization: the provision and subsequent utilization
of space in a rocky intertidal community. Ecol. Monogr. 41:
351-389.

HarcGer, J. R. E. 1968. The role of behavioral traits in influ-
encing the distribution of two species of sea mussel, Mytilus
edulis and Mytilus californianus. Veliger 11:45-49.

HarcGer, J. R. E. 1970a. Comparisons among growth char-
acteristics of two species of sea mussel, Mytilus edulis and
Mytilus californianus. Veliger 13:44-56.

HarGer, J. R. E. 1970b. The effects of species composition
on the survival of mixed populations of the sea mussels
Mytilus californianus and Mytilus edulis. Veliger 13:147-152.

Harcer, J. R. E. 1972a. Variation and relative “niche” size
in the sea mussel Mytilus edulis in association with Mytilus
californianus. Veliger 14:275-283.

Harcer, J. R. E. 1972b. Competitive coexistence: mainte-
nance of interacting associations of the sea mussels Mytilus
edulis and Mytilus californianus. Veliger 14:387-410.

Hewatt, W. G. 1935. Ecological succession in the Mytzlus

J. H. Petersen, 1984

californianus habitat as observed in Monterey Bay, Califor-
nia. Ecology 16:244-251.

KANTER, R. G. 1977. Structure and diversity in Mytilus cali-
fornianus (Mollusca: Bivalvia) communities. Doctoral The-
sis, University of Southern California, Los Angeles.

KELLEY, R. N., M. J. ASHWOOD-SMITH & D. V. ELLIs. 1982.
Duration and timing of spermatogenesis in a stock of the
mussel Mytilus californianus. J. Mar. Biol. Ass. U.K. 62:
509-519.

LeEvIN, S. A. & R. T. Paine. 1974. Disturbance, patch for-
mation, and community structure. Proc. Natl. Acad. Sci. 71:
2744-2747.

NoORTON-GRIFFITHS, M. 1967. Some ecological aspects of the
feeding behavior of the oystercatcher Haematopus ostralegus
on the edible mussel Mytilus edulis. Ibis 109:412-424.

PAINE, R. T. 1966. Food web complexity and species diversity.
Amer. Natur. 100:65-75.

PaINE, R. T. 1974. Intertidal community structure. Experi-
mental studies on the relationship between a dominant com-
petitor and its principal predator. Oecologia 15:93-120.

PaINE, R. T. & S. A. LEvIN. 1981. Intertidal landscapes: dis-
turbance and the dynamics of pattern. Ecol. Monogr. 51:
145-178.

Paris, O. H. 1960. Some quantitative aspects of predation by
muricid snails on mussels in Washington Sound. Veliger 2:
41-47.

Page 13

PETERSEN, J. H. 1983. Habitat selection, distribution and ear-
ly survivorship of the marine mussel Mytilus californianus
Conrad. Doctoral Thesis, University of Oregon, Eugene.

PETERSEN, J. H. 1984. Larval settlement behavior in compet-
ing species: Mytilus californianus Conrad and M. edulis L.
Manuscript in review.

PETRAITIS, P.S. 1978. Distributional patterns of juvenile Myt-
ilus edulis and Mytilus californianus. Veliger 21:288-292.

SEED, R. 1969. The ecology of Mytilus edulis L. (Lamelli-
branchiata) on exposed rocky shores. 1. Breeding and set-
tlement. Oecologia 3:277-316.

SEED, R. 1976. Ecology. Pp. 13-65. In: B. L. Bayne (ed.),
Marine mussels: their ecology and physiology. Cambridge
University Press: Cambridge.

SooT-RYEN, T. 1955. A report on the family Mytilidae (Pe-
lecypoda). Alan Hancock Pacific Exped. 20:1-174.

SUCHANEK, T. H. 1978. The ecology of Mytilus edulis L. in
exposed rocky intertidal communities. J. Exp. Mar. Biol.
Ecol. 31:105-120.

SUCHANEK, T. H. 1979. The Mytilus californianus community:
studies on the composition, structure, organization, and dy-
namics of a mussel bed. Doctoral Thesis, University of
Washington, Seattle.

SUCHANEK, T. H. 1981. The role of disturbance in the evolu-
tion of life history strategies in the intertidal mussels Mytilus
edulis and Mytilus californianus. Oecologia 50:143-152.

The Veliger 27(1):14-18 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

Observations on the Spawn of Three

Species of Conus from the

Golfo Triste, Venezuela

PABLO E. PENCHASZADEH

INTECMAR and Departamento de Estudios Ambientales, Universidad Simon Bolivar,
Apartado 80659, Caracas, Venezuela

Abstract. ‘The spawn of three species of southern Caribbean Conidae was studied. Conus spurius
differs strikingly from all other known species of the genus by having the largest recorded eggs (690
um in diameter) and the fewest eggs per capsule (23-83); the hatching stage is a veliconch with a shell
length of 1300 wm. The spawn of C. centurio is also noteworthy. The eggs of most Conus species are
either large or small; however, those of C. centurio are intermediate in size (275 um). The number of
eggs per capsule is 1750 in this species, and the hatching stage is a free swimming veliger 320 um in
shell length. Egg capsules of the third species, C. ermineus, contain an average of 2373 embryos each,

and the larval shell on hatching is 295 um in length.

INTRODUCTION

THE FAMILY Conidae is represented by a large number of
species distributed mainly in the tropical and subtropical
seas. Characteristics of spawning have been studied for
many species, especially those from the Pacific and Indo-
Pacific oceans (RISBEC, 1932; THORSON, 1940; OSTER-
GAARD, 1950; NATARAJAN, 1957; KOHN, 1961a, b; PERRON,
1981a, b, c, 1983). In the Caribbean area, research has
been done on several species (LEBOUR, 1945; D’ASARO,
1970; BANDEL, 1976). Data on more than 45 species sug-
gest that there is a common pattern for the egg mass and
a single type of egg capsule. However, specific differences
are present in the arrangement of the egg capsules and
their size and shape, and in the number and diameter of
the eggs.

This study describes the egg masses, capsules, eggs, and
hatching stage of three species of Conus: C. spurius Gme-
lin, 1791, C. centurio Born, 1778, and C. ermineus Born,
1778. Several of the features described are uncommon
among conids.

MATERIALS anp METHODS

Five adult specimens of Conus spurius were obtained by
trawling at 35-40 m depth in the Golfo Triste (January
1977). These were kept in a non-circulating seawater
aquarium, 22~—28°C, with a mixed substratum of sand and
small stones. ‘Two egg masses laid by a single individual
on the walls of the aquarium were obtained. Four speci-

mens of C. centurio were obtained from a depth of 42 m
(February 1977) and maintained in aquaria as above.
These produced five egg masses on the walls of the aquar-
la, as well as one on the shell of one of the adults.

Egg masses collected from nature during trawls in the
Golfo Triste at depths between 35 and 45 m were also
studied (three of C. spuritus and three of C. ermineus). A
total of nine adult C. ermineus were maintained in aquaria
but never laid egg masses.

RESULTS

Conus spurius

The two egg masses laid in the aquarium consisted of
18 and 21 egg capsules respectively. The capsules were
arranged in levels; some were attached by a basal mem-
brane to the substratum (the aquarium wall) and addi-
tional egg capsules were attached to the original ones.
Other capsules were attached to the second layer, and so
on to form six layers (Figure 1).

The egg capsule has a tongue-like shape, with a pre-
formed, sub-oval exit aperture closed by a transparent
membrane at the upper extreme. The strong walls of the
egg capsule are opaque white, with noticeable wrinkles.
The dimensions were 11.2-13.2 mm high, 7.3-9.1 mm
wide, and 3.0-4.0 mm thick. Egg masses collected in na-
ture had 32, 17, and 27 egg capsules identical to those
described above.

P. E. Penchaszadeh, 1984

Conus spurius. A. View of a fragment of an egg mass. B. Front
view of an egg capsule. C. Back view of an egg capsule. D. View
of the tip of an egg capsule. E. Outline of the shell at hatching.

Egg number in capsules was constant for each egg mass,
but there was wide variation between the different egg
masses examined. In the egg masses obtained in the lab-
oratory, we counted between 23 and 36 eggs per capsule,
whereas in the egg masses collected in nature, we found
23-36, 41-53, and 76-83 embryos in each egg capsule.
The number of eggs seemed to be related to the size of
the egg capsule.

Uncleaved ova measured between 687 and 707 um in
diameter (mean 690 wm). All of the embryos developed,
and the shell size at hatching was 1200-1302 wm (mean
1297 um), both in egg masses collected from the aquarium
and from nature. The crawling stage was a veliconch with
a well-developed foot and a very small velum.

Conus centurio

We obtained a total of 32 egg capsules on the aquarium
walls, ordered in rows with as many as 8 egg capsules per
row. An egg mass consisting of 13 capsules was also laid
on the shell of one adult C. centurio (Figure 2).

Page 15

The egg capsules were leaf-like and asymmetrical when
seen from the front, with one side more developed than
the other; they were almost completely transparent. The
sizes of the egg capsules were very constant, being 12.8
mm high, 7.8 mm wide, and 3.1 mm thick. The capsules
were not arranged in levels. In each capsule, 1731 to 1772
eggs developed. The uncleaved egg diameter was 275 um,
and the shell size of the free swimming veliger at hatching
was 320 wm. Hatching occurred through a preformed,
elongate escape aperture at the top of the egg capsule
(Figure 3).

Conus ermineus

Three egg masses assigned to that species, common in
the Golfo Triste, were found at depths between 30 and
50 m, and contained 13, 19, and 31 egg capsules respec-
tively. The egg capsules were arranged in layers, the first
of which was attached directly to the substratum (an emp-
ty shell in the three cases) with the other egg capsules
attached to the first. Three layers were found in two egg
masses, whereas the third egg mass consisted only of a
row in a single layer. The flattened, white egg capsules
were leaf-like, with relatively weak and semi-transparent
walls, and bore large, superficial and transverse wrinkles.
The mean size of egg capsules was 18.8 mm high, 15.3
mm wide, and 2.0 mm thick. In each egg capsule, between
2221 and 2420 embryos (mean 2373) developed, hatching
as free swimming veliger larvae. The size of the larval
shell upon hatching was 295 um. Escape was made through
a very elongate, preformed aperture at the top of the cap-
sule on the upper margin (Figure 4).

DISCUSSION

There are major differences within the genus Conus in
regard to the number of eggs per capsule and the egg
diameter. A review of the literature indicates that an in-
verse relation exists between the two (Figure 5). Of the
many species studied by KOHN (1961a, b), all of those
characterized by small egg diameters hatched as free
swimming veligers; he found no species with nurse eggs.
In contrast, OSTERGAARD (1950) reported that in the large-
egged C. pennaceus (egg diameter 460 wm; 80 eggs per
capsule) eclosion takes place at a veliconch stage, virtually
without a pelagic stage (not more than one day in the
plankton). PERRON (1981a, b, c, 1983) has confirmed Os-
tergaard’s observations on C. pennaceus and has found
between 25 and 250 ova per capsule. Another Pacific
species, C. glans, also produces eggs with large diameters
(440 wm) and hatches as a veliconch with little or no
pelagic stage (KOHN, 1961b). Conus araneosus from India
has large eggs of 467-517 um (NATARAJAN, 1957), but
details of hatching are unknown. Furthermore, our results
on C. spurius indicate that this species has the largest egg
diameter among those reported for the genus, as well as
the lowest number of ova per capsule. The shell size on
hatching is, with C. pennaceus, the largest registered (880

Page 16 The Veliger, Vol. 27, No. 1

Figure 2

Conus centurio. Spawn attached to an adult C. centurio (natural size) and detail of two egg capsules (3 x).

AL
B fh \
Lg
* = a
\ S = Ae =
\ \ Bee 8
\ 5mm >

\ UR
ae \ Ne
\ F\ )
Se & /
5 Cy
pS eee iG (of
Conus centurio. A, B, and C. Front (A), back (B), and tip (C) Conus ermineus. A. View of a fragment of an egg mass. B, C,

views of an egg capsule. and D. Front (B), back (C), and tip (D) views of an egg capsule.

P. E. Penchaszadeh, 1984

100000

10000

1000

100

NUMBER OF EGGS / EGG CAPSULE

100 200 300

Page 17

400 500 600 700
EGG DIAMETER (mu m)

Figure 5

Number of eggs per egg capsule and egg diameter, for 26 species of Conus. 1 = C. centurio, 2 = C. spurius; other
data taken from KNUDSEN (1950), OSTERGAARD (1950), NATARAJAN (1957) and KOHN (1961a, b).

um in C. glans, KOHN, 1961b; 1100 um in C. araneosus,
NATARAJAN, 1957; 1200-1250 wm in C. pennaceus,
OSTERGAARD, 1950, and PERRON, 1981a). The character-
istics of the hatching form in C. spurius suggest no pelagic
stage or a very short time in the plankton. However, D’A-
SARO (1970) studied the spawn of C. spurius atlanticus
from Florida, and suggested that development in this sub-
species indicated a planktotrophic veliger stage; he found
59 eggs per capsule, but did not report egg diameters, size,
or characteristics of the hatching stage.

The eggs of most Conus species are either large or small
(Figure 5). Those of C. centurio, however, are interme-
diate in size, and, together with those of C’ textile and C.
striatus (PERRON, 1981b), they provide the only recorded
examples of Conus eggs with diameters between 240 and
340 um.

The pattern exemplified by C. ermineus is more com-
mon: large numbers of eggs per egg capsule and small egg
diameters, with hatching taking place as veliger larvae
that presumably remain in the plankton for some time. It
is interesting to note, however, that BANDEL (1976),
studying Colombian material, reported C. ermineus egg
capsules with a considerably lower number of eggs (“about
500’) than found by us in the Golfo Triste (about 20%
of our totals).

The egg mass of C. spurius has all the characteristics
reported by D’Asaro (1970) for C. spurius atlanticus, and

it is also very similar to the description given for the Indo-
Pacific C. pennaceus in the arrangement of the egg cap-
sules in layers and in having decurved capsules (OSTER-
GAARD, 1950; KOHN, 1961b). In C. ermineus, egg capsules
are arranged in rows in a single layer as BANDEL (1976)
described, or in as many as three layers; egg capsules of
C. ermineus were the largest egg capsules we recorded in
the Golfo Triste Conus material.

ACKNOWLEDGMENTS

I thank Luis José Gonzalez for his assistance aboard and
in the laboratory, Carlos Alamo for his assistance in the
laboratory, Dr. Jack Gibson-Smith of the Universidad
Central de Venezuela for the identification of adult spec-
imens, and CONICIT, Venezuela, for grant S1-0775
which supported this study. I would also like to thank Dr.
Alan Kohn, University of Washington, for his valuable
criticism.

LITERATURE CITED

BANDEL, K. 1976. Spawning, development and ecology of some
higher Neogastropoda from the Caribbean Sea of Colombia
(South America). Veliger 19(2):176-193.

D’Asaro, C. N. 1970. Egg capsules of prosobranch mollusks
from South Florida and the Bahamas and notes on spawn-
ing in the laboratory. Bull. Mar. Sci. 20(2):414-440.

Page 18

KNUDSEN, J. 1950. Egg capsules and development of some
marine prosobranchs from tropical west Africa. Atlantide
Rep. 1:85-130.

Koun, A. J. 1961a. Studies on spawning, behavior, egg masses
and larval development in the gastropod genus Conus. Part
I. Observations of nine species in Hawaii. Pacific Sci. 15:
163-180.

Konun, A. J. 1961b. Studies on spawning, behavior, egg masses
and larval development in the gastropod genus Conus. Part
II. Observations in the Indian Ocean during the Yale-Sey-
chelles expedition. Bull. Bingham Oceanogr. Coll., Peabody
Mus. Natur. Hist. Yale Univ. 17(4):1-51.

Lesour, M. 1945. The eggs and larvae of some prosobranchs
from Bermuda. Proc. Zool. Soc. Lond. 114:462-489.

NaTARAJAN, A. V. 1957. Studies on the egg masses and larval
development of some gastropods from the Gulf of Mannar
and the Palk Bay. Indian Acad. Sci. 46:170-228.

OSTERGAARD, J. M. 1950. Spawning and development of some
Hawaiian marine gastropods. Pacific Sci. 4:75-115.

The Veliger, Voli 273 Nom

PERRON, F. E. 1981a. Larval growth and metamorphosis of
Conus (Gastropoda: Toxoglossa) in Hawaii. Pacific Sci. 35:
25-38.

PERRON, F. E. 1981b. Larval biology of six species of the genus
Conus (Gastropoda: Taxoglossa) in Hawaii, USA. Mar. Biol.
61:215-220.

PERRON, F. E. 1981c. The partitioning of reproductive energy
between ova and protective capsules in marine gastropods
of the genus Conus. Amer. Natur. 118:110-118.

PERRON, F. E. 1983. Costs of parental care in the gastropod
Conus pennaceus: age-specific changes and physical con-
straints. Oecologia 55:319-324.

RisBec, J. 1932. Notes sur la ponte et le développement de
mollusques Gastéropodes de Nouvelle-Calédonie. Bull. Soc.
Zool. France 57:358-374.

TuHorRSON, G. 1940. Studies on the egg-masses and larval de-
velopment of gastropods from the Iranian Gulf. Danish In-
vest. Iran, Part I], Munkgaard, Copenhagen, pp. 159-238.

The Veliger 27(1):19-28 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

The Rhythmic Activity of Nautilus pompilius,

with Notes on its Ecology and

Behavior in Fiji

by

LEON P. ZANN

Institute of Marine Resources, The University of the South Pacific,
Suva, Fiji

Abstract.

Specimens of Nautilus pompilius were trapped on the sea floor in depths of 450 to 500 m

off Suva, Fiji. As found in other studies, these were mainly mature (mean shell diameter 13.3 cm,
range 10.3-15.2 cm; n= 74) males (90-94%). Eleven individuals were kept under simulated natural
conditions (0.1 lux daylight intensity; 10-15°C) and activities were recorded constantly for a total of
80 days. Activity was characterized by bursts or periods of swimming (minor during the day; 5-12 min
at night) every 30 to 50 min. These were termed “‘subcycles.”” Activity was crepuscular/nocturnal.
Healthy, freshly collected specimens swam for an average of 160 min/day: 2.6 min/h during daylight,
11.9 min/h at dusk, 7.0 min/h during night, and 6.2 min/h at dawn (n = 4; 25 days of records). A
rhythm comprising an innate subcycle of 30 to 50-min periodicity, modified by daily cycles of photo-
period, and an endogenous 24-h periodicity is proposed. Aquarium behavior is related to the natural
habitat. It is proposed that the subcycles of activity are a strategy for hunting and scavenging in a
homogenous environment where food is limited. Nautilus swam about 1600 m/day, of which most (1350
m) was at night. It is, therefore, unlikely that the population studied migrate at night to the nearest
reefs (6000 m away) as suggested elsewhere. Brief notes are also included on the habitat, aquarium
behavior, and growth rates of Nautilus in captivity.

INTRODUCTION

THE FOUR species of living Nautilus (SAUNDERS, 1981)
are relicts of a large group of shelled cephalopod mollusks
that flourished in the world’s seas from the Triassic to the
Tertiary, 225 to 65 million years ago. Because of the im-
portance of the nautiloids and ammonoids in the fossil
record, paleoecologists have shown considerable interest
in establishing the ecology, behavior, and life history of
living Nautilus, which are little known because of their
deep water habitat and restricted distribution.

The present study investigates the activity patterns of
Nautilus pompilius Linnaeus, a species found in depths of
100 to 650 m on reef slopes in the Philippines, Indonesia,
New Guinea, Solomon Islands, possibly northeastern
Australia, Vanuatu, and Fiji (WARD et al., 1977;
SAUNDERS, 1981).

A number of studies indicate that the Nautilus species
are nocturnal. WILLEY (1902) suggested that they move
up reef slopes from deepwater at night. BIDDER (1962)
noted that captive N. macromphalus swam chiefly at night
and spent most of the day at rest on the bottom. HAVEN

(1972) described Philippine Nautilus pompilius as “diur-
nal” in activity, as only baited traps left overnight caught
specimens. WARD ef al. (1980) reported that the New
Caledonian N. macromphalus had been observed swim-
ming actively near the surface at night by divers, indicat-
ing that they are inactive during the day or migrate into
deep waters. Carlson (DUGDALE, 1982 and personal com-
munication) has evidence from specimens of N. belauensis
released with telemeters that suggests that this species does
move vertically, from 400 m to 100 m, at night.
Although specimens of Nautilus have been successfully
kept in aquaria for periods of up to one year (JECOLN,
1980), there have been only superficial observations on
their activity cycles. Nautilus macromphalus kept in aquar-
ia in New Caledonia and Japan were reported to be active
after sunset (MIKAMI & OKUTANI, 1977; JECOLN, 1980),
and HAVEN (1972) noted that N. pompilius in aquaria in
Philippines became active at dusk. HAYASAKA et al. (1982)
made two days of visual observations on captive N. pom-
pilius, and found they were most active at about dawn on
both mornings. They concluded: “‘As far as our observa-

a]

Laucala Bay

pin enuaias

Cer d

MU o\ a) Badia

wt
ay mnt taen Sy S

cies?

The Veliger; Vola 27-0 Niowm

Figure 1

A. Collection site (x) off Suva Reef, Viti Levu Island, Fiji. B. Depth profile (meters) along transect in A, with

kite diagram (arbitrary scale) of Nautilus distribution.

tions are concerned, it is hard to say that Nautilus is a
nocturnal animal.” A histogram of the data presented in
HAyYASAKA et al. (1983) also shows some activity after
sunset (“‘lights-off’) and a major peak before dawn
(“‘lights-on’’); the authors considered that this activity may
have been induced by the bright lights of the display
aquarium.

In the present study, the swimming activity of 11 spec-
imens of Nautilus pompilius held under simulated natural
conditions of temperature and light was continuously
monitored by activity recorder. Light and temperature re-
gimes were also manipulated in an attempt to establish
the nature of the rhythmicity. As little is known of the
ecology or general behavior of Nautilus, some associated
observations are also presented as a background to the
study of swimming rhythmicity.

MATERIALS anD METHODS

Specimens of Nautilus pompilius were captured in chev-
ron-shaped fish traps (1.80 x 0.9 x 0.6 m; conical en-
trance 20 cm in diameter) set on the sea floor at depths
of 400 m to 500 m off Suva, Fiji (Figure 1). To determine
whether Nautilus were leaving the bottom, four smaller
traps were also placed at 20-m intervals from the bottom
on the mooring line. The study site, 8 km south of the
University of the South Pacific, was 4-5 km south of
Nukubuco reef, and about 7 km east of the area where
WarD et al. (1977) collected their Nautilus. Slightly de-
caying skipjack tuna was the most effective bait used. Ini-
tial surveys indicated that Nautilus was most abundant at
450-500 m. A total of 150 underwater photographs was
taken of this area with a bottom-triggered Ewing deep-
water camera.

Ninety specimens of Nautilus were obtained from eight
trap series that were set at two to six week intervals be-
tween September 1982 and April 1983. Average catch per
trap per day was 3.1 individuals (range 1.0-8.3). On each
occasion two or three specimens were quickly returned to
the laboratory in darkened containers of cooled seawater
while other captives were either preserved or measured,
tagged, and released. No recaptures were made.

Each Nautilus was held in a dark-sided, 100-L capacity
aquarium of recirculating, charcoal-filtered and refriger-
ated seawater (10-14°C; salinity 34.5-35.5%o). The
aquaria were kept in a darkroom that could be indirectly
illuminated by a 15-cm diameter skylight with a 10 x
neutral-density filter to further reduce light intensity. This
illumination, of about 0.1 lux at mid-day and very dim to
human eyes, approached that of natural conditions (0.004%
of surface intensity of 470 nm light at 500 m). Artificial
light, when necessary, was provided by indirect illumi-
nation from a 40-watt fluorescent light (approximately 2
lux). A red photographic safelight provided illumination
when servicing the equipment in darkness. Disturbances
were restricted to a daily instrumentation check and week-
ly feeding, cleaning, and water change. When available,
several live deepwater carid shrimps, a possible prey of
Nautilus, were left in the aquarium to provide a regular
food source. At other times, Nautilus were fed on shrimp
and fish during the day, although this tended to increase
the duration of daytime activity.

Nautilus lived for up to three months under these con-
ditions; they fed regularly and grew various amounts.
However, all specimens became positively buoyant—they
are usually neutrally buoyant—after several days of cap-
tivity.

Swimming activity was monitored directly and indi-

L. P. Zann, 1984

Figure 2

Activity recorders. Movements in a thread (a), counterweighted (b) and redirected by a pulley (c), were detected
by a strain-gauge (d), amplified and recorded. Alternatively, a plastic wire panel (e) was suspended from a strain-
gauge (f) that recorded a signal if touched by a swimming Nautilus. A single animal was placed in each dark-sided

tank; water was constantly filtered (g) and cooled (h).

rectly. In the direct method, a cotton thread was glued
with quick drying “Superglue’™ to the dorsal surface of
the shell, and passed through a small pulley fixed above
the aquarium to a light counterweight (1 to 2 g) which
kept tension on the thread. An engineering strain gauge,
fitted to the pulley, detected any slight movement in the
system. A slow-speed (10 cm/h) chart recorder recorded
an amplified signal. The behavior of the Nautilus did not
appear to be influenced by the slight friction of the pulley
and counterweight but, to test this, an indirect recorder
was also used for several experiments. This consisted of a
rectangular plastic wire panel, weighted at the bottom and
equipped with a float at the top, directly attached by thread
to the strain gauge. To swim from one end of the tank to
the other, the Nautilus had to make contact with the panel.
Small, local movements were not detected. Because of the
possibility of changes in behavior resulting from accli-
mation to the artificial conditions and activity recorder,
Nautilus were usually replaced by freshly collected spec-
imens after one week.

RESULTS
General Ecology and Aquarium Behavior

The outer-reef slope of Suva barrier reef initially slopes
steeply to about 200 m depth, then more gradually to 500
m at about 4-5 km from the reef (Figure 1A). Nautilus
were trapped in shrimp traps between 100 and 600 m,
and were most abundant at 450-500 m (King, personal
communication). No Nautilus were ever trapped in the
traps suspended above the bottom, indicating that they
rarely if ever leave the sea floor. Underwater photographs
of the sea floor showed a uniformly soft bottom of terrig-
inous clays from the nearby Rewa River, highly biotur-
bated by polychaete and other burrowers. No Nautilus
were seen in 150 frames, covering about 3000 m? of sea
floor. Crustaceans trapped in this area included carid
shrimps (Heterocarpus; Plesionika; Parapandalus), galathe-
ids (Munida), majid crabs (Myra; Hyastenus), goneplacids
(Geryon), portunids (Carybdis), homolids (Homola), sev-
eral pagurids (Parapagurus, etc.), and panulurids. Several

The Veliger) VolyZi-eiomal

10 11 12 13 14 15
MAX. DIAMETER (™

Figure 3

A. Size frequency distribution of Nautilus captured. These were
collected from the same site over a 6-month period. B. Subsample
of A, showing size of mature (black) and immature (white) spec-
imens.

species of gorgonians, solitary corals, antipatharians, and
hydrozoans, as well as a number of bivalves, gastropods,
holothurians, ophiuroids, and echinoids were dredged from
this area. A large number of species of fishes have been
collected from the 100-600 m zone of Fijian reef slopes
(Raj & Seeto, unpublished data).

Epizoites were present on some Nautilus shells. Clusters
of between two and six of the small pedunculate barnacle
Temnaspis excavatum (Hoek) were present on the umbos
and ventral part of the shell, near the hyponome, of about
15% of Nautilus specimens. This barnacle has previously
been recorded attached to isopods, crabs, and other bar-
nacles from 200 to 400 m depths in the Indo-Pacific
(Foster, personal communication). Isolated serpulid worm
tubes were present on about 5% of specimens. On average,
five of the ectoparasitic caligid copepod Anchicaligus nau-
tili (Willey) were present on the shell and soft parts of
each of ten Nautilus carefully examined.

The mean shell diameter of the Nautilus collected was
13.3 cm (mode 13.8 cm; range 10.3-15.2 cm; n = 74; Fig-
ure 3A). In the other studies of Nautilus off Suva, WARD
et al. (1977) reported a mean diameter of 14.16 cm (n=
22) and TANABE et al. (1983) of 13.5 cm (n = 31). The
shells of Fijian N. pompilius are variable in coloration. In
about 60% of the shells, bands extended to the umbo and
in the remainder they did not (termed variants A and B
respectively by WARD et al., 1977). Of 50 specimens dis-
sected, three were females and two immature specimens
were probably females—z.e., only 6% to 10% were fe-
males. WARD et al. (1977) reported 14% females, and
TANABE et al. (1983) reported 25% females in their Fijian
studies. About half the sample examined (26 of 49) had
definite eye notches, indicating their maturity. Notches
appeared at 13.2-13.4 cm shell diameter, and all speci-
mens above 13.8 cm had notches (Figure 3B). All studies
of Nautilus since WILLEY’s (1902) have found a similar
anomalous predominance of males and an absence of ju-
veniles, implying that the young and females either live

in other habitats or are not prone to trapping. Little is
known of the life-cycle of Nautilus.

Freshly captured Nautilus were gorged on fish bait (av-
erage gut contents 51 g; range 4-85 g; n= 10), and fed
little for the first week. They subsequently consumed about
20-40 g of dead shrimp per week, showing a preference
for the head. .

Immature specimens kept for two months in the aquar-
ium showed some growth. Individuals 11.6 cm, 12.1 cm
and 13.1 cm in shell diameter added 3.6 mm, 2.7 mm and
2.2 mm respectively to the apertural margin per month.
Note that this represents an increase of spiral circumfer-
ence of about 1%, and there was little measurable increase
in overall shell diameter.

Three of 45 living specimens examined had triangular
bites out of the apertural margin matching the gape of
a Nautilus jaw. HAVEN (1972) proposed that these are
received in intraspecific fighting. One juvenile drift shell
from Suva (5.5 cm in diameter) had a fresh bite from the
margin, suggesting that these fights might sometimes be
fatal or, alternatively, that smaller Nautilus may some-
times be eaten by larger Nautilus or squid.

The swimming behavior and tentacle positions were
similar to those described by HAVEN (1972). When rest-
ing, Nautilus attached to a solid object with one or two
tentacles, and slowly rocked to-and-fro with its respiratory
pulses. This was regularly interrupted by a few seconds
of minor activity and repositioning. When feeding, Nau-
tilus extended its tentacles and swam forward in BIDDER’s
(1962) “cone of search,” but at other times Nautilus swam
backwards. During periods of slow swimming, usually of
about 3 to 10 min in duration, the tentacles were either
trailing or in HAVEN’s (1972) “‘cat’s whiskers” pose, and
any obstacles in the aquarium were carefully avoided.
Nautilus generally took several hours to learn the spatial
arrangements of the tank, and became quite adept at
avoiding the activity panel. When alarmed, and occasion-
ally spontaneously, for no apparent reason, Nautilus swam
very vigorously for 30 sec to 2 min, often colliding with
the sides of the aquarium. Tentacles were usually short-
ened during flight.

Of 11 Nautilus examined, 6 individuals (Specimens No.
1, 2, 5, 6, 9, and 10) remained active and fed regularly
during the duration of the experiments, from 4 to 36 days.
Specimen No. 4 died on the sixth day of recording; No. 7
and 11 were moribund during the first two days of re-
cording and were terminated, and No. 8 was highly stressed
for the first two days of recording and moved continuously.
It was noted that most specimens that became moribund
had enlarged spadices. An autopsy on one specimen showed
that a newly formed septum had fractured, and a sliver
of shell had perforated the viscera.

Activity Rhythms

About 80 days of activity records from 11 mature male
Nautilus were obtained; of these, about 20 days were dis-

L. P. Zann, 1984

Page 23

Figure 4

A. Actual records of activity of Specimen No. 1. Days 2 to 5 under normal photoperiod (L/D). Days 11 to 12
under constant light (L/L). Day 13 under constant darkness (D/D). Note subcycles of activity, especially under
constant conditions. Differences in amplitude result from different gain settings on amplifier. B. Detail of recording

for day 12. Horizontal axes: time in hours.

carded because of equipment malfunctions and erratic or
moribund specimens. Malfunctions and power losses re-
sulted in gaps of several hours in many records.

Records (Figure 4) clearly indicate the minor move-
ments involved in position changing and the major move-
ments of swimming activity above a thick baseline of elec-
trical interference and shell rocking movements associated
with the respiratory pulses. Activity was characterized by
regular short periods or bursts of swimming of several
minutes duration, followed by a longer period of inactiv-

ity. These are referred to as “subcycles” of activity. To
determine whether the pattern of subcycles was a fatigue
response due to the tethering to the activity recorder or to
an innate pattern of activity, three Nautilus were tested in
the panel activity recorder. These showed identical sub-
cycles of activity and resting, indicating an innate behav-
ior.

For analyses, the continuous records were arranged into
hourly lots, and the duration of the swimming activity
summed for each hour. The hourly activities of two Nau-

Page 24
SNE ENON

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10+ SS Ry
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TIMECH)

Figure 5

Summed activities for each whole hour, Specimen No. 1. Days
1 to 6 under normal photoperiod (L/D), days 7 to 11 under
constant light (L/L). Shading represents night; dashed lines,
dawn and dusk. Note nocturnal rhythm on days 2 to 6 (L/D)
and on day 9 (L/L).

tilus over a total of 27 days are shown in Figures 5 and
6. Because the period of activity/inactivity was sometimes
about one hour, hourly records may show alternate high
and low activities, obscuring the general trend. Average
activity for each hour of the day was therefore calculated
to randomize sporadic activity or “noise,” the subcycles,
and the breaks in records. These show a pronounced noc-
turnal activity under “normal” photoperiod (Figure 7).
The activities of nine Nautilus over a total of 44 days

The Veliger, Vol. 27, No. 1

a uo

a

a

Saas errno | (enna

ACTIVITY (mins/ur)
a
SSS ee

a

a
Me

a

TIME (H )

Figure 6

Summed activities for each whole hour, Specimen No. 9 (from
partition recorder). The decline in activity after day 5 is partially
due to an avoidance of the panel.

are analyzed in Table 1. The average duration of swim-
ming per day varied from individual to individual, with
the moribund specimen (No. 4) and the two tested under
the less sensitive panel activity recorder (No. 9 and 10)
least active. Nautilus swimming activity averaged between
52 and 188 min/day, with the higher figures (170-188
min/day) the more credible because of those specimens’
good health in the aquarium.

The duration of swimming activity quickly declined in
the moribund specimen and gradually declined in the
healthy specimens (Figure 6). The duration of activity on
successive days of recording of Nautilus Specimens No. 1,
2, 5 and 6 are illustrated in Figure 8. After initially high
activities on the first day of capture (due to the stress of
capture and exploration of the new surroundings) activity
declined to between 120 and 160 min per day. Activity
increased in No. 6 on days 7 to 9, and in No. 1 on day 6,
the days of, and following, feeding.

L. P. Zann, 1984

No. 1(5 Days)

5 No.2 (6pays)

No.4 (4pays)

a

my
o)

fan ny fn

No.6 (8 Days)

= No.9 (12 pays)

54

ACTIVITY (mins/HR)

Nno.10(3 pays)

16 18 20 22 24

TIME (H)

Figure 7

Average hourly activities of a number of days of recording (in-
dicated) of six specimens. Note increased activity at dusk and
anticipation of dusk in Specimens No. 2 and 9.

Under normal photoperiod, activity was lowest during
the daylight hours (0700 to 1600) for all specimens on all
days (average activities ranged from 0.9 to 3.0 min/h)
(Figures 5 to 7; Table 1). Activity was highest at dusk
(1600 to 1900) in all specimens (averages from 5.3 to 19.0
min/h) but continued throughout the night (averages from
2.3 to 9.3 min/h). Activity was not uniform during the
night and several specimens showed three or four peaks
of activity (including dusk) at about 4-h intervals. Dawn
activity (0400 to 0700) was approximately similar to the
nocturnal levels (averages from 1.1 to 8.7 min/h). Dusk
activity often commenced before the actual dusk (e.g.,

Page 25

Specimen No. 9, Figure 6). On several occasions Nautilus
were held under artificial light during the day, and dusk
occurred as a sudden “‘lights-off.” In most cases, activity
preceded “‘lights-off” indicating that Nautilus anticipate
dusk and are not stimulated to move solely by fading after-
noon light.

To further test whether the nocturnal activity was an
exogenous rhythm (controlled solely by environmental
cycles) or an endogenous one (controlled by an internal
or innate “biological clock”), Specimen No. 1 was placed
under constant conditions after a period of normal pho-
toperiod (Figure 5). Unfortunately, the record for the first
night was lost due to equipment malfunction; day 2 of
constant light showed random activity; day 3 showed a
clear nocturnal rhythm; and days 4 and 5 showed random
activity. This animal was later subjected to five days of
constant darkness; hourly records showed uniform or ran-
dom activity with the regular subcycles of activity predom-
inating.

To determine the effects of temperature on the duration
of swimming activity and on the general behavior of Nau-
tilus, three specimens were subjected to a range of tem-
peratures between 11 and 19°C (Figure 9). The average
activities for each day (expressed as min/h) for two spec-
imens were variable, while the other was more uniform.
No specimens showed any increase in activity at the higher
temperatures although this had been expected on meta-
bolic grounds.

The subcycles of activity were relatively regular in their
period from activity to activity, and in the duration of the
activity, but they differed somewhat from individual to
individual. The average duration of swimming in each
subcycle of activity for the first three days of recording for
Nautilus Specimens No. 1, 2, 5, and 6 was 6.7 min (in-
dividual averages ranged jean 4.5 to 11.9 min; n = 300
measurements). The period of the subcycles, the time from
the commencement of one activity to the commencement
of the successive activity, averaged 41 min (individual av-
erages ranged from 31 to 51 min; n = 300) (Table 1).

DISCUSSION

Nautilus held under simulated natural conditions were
mainly nocturnal with a pronounced peak of activity at
dusk. Their behavior was characterized by brief periods
of swimming, followed by periods of inactivity or resting,
at about 30 to 50 min intervals. These were termed “sub-
cycles” to distinguish them from the 24-h rhythmicity.
During the daylight hours the activity was minor, ranging
from brief repositioning movements to a minute or so of
slow swimming. During the night Nautilus alternately
swam for between 5 and 12 min at a time and rested for
about 20 to 40 min.

Under normal photoperiod (L/D) all the Nautilus ex-
amined were more active at night. Four freshly collected,
healthy specimens tested over a total of 25 days were ac-

Page 26

ACTIVITY (™INS/HR)

DAY

The Veliger, Vole27FyNoms

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fon)
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00

Figure 8

Daily activities (expressed as average activity in minutes per hour) of successive days of captivity for Nautilus

Specimens No. 1, 2, 5, and 6.

tive for an average of 160 min/day. This period was not
overtly affected by temperature (11-19°C range) although
this might be expected on metabolic grounds. Their av-
erage activity during the hours of daylight was 2.6 min/
h, at dusk 11.9 min/h, during the night 7.0 min/h, and
at dawn 6.2 min/h.

The nocturnal rhythm did not persist under constant
conditions of darkness (D/D) or light (L/L), but did
reappear on one occasion after several days. However,
because Nautilus regularly began moving an hour before
dusk, before any decline in light intensity, the 24-h peri-
odicity may be innate or endogenous.

The characteristic 5-12 min of activity each 30-50 min
seen at night under normal photoperiod (L/D) continued
for the entire 24 h under constant conditions of light (L/

ACTIVITY (uins/uR)

Oo oO oO oO oO £0)

10 12 14 16 18 20
TEMP (C°)
Figure 9
Daily activities (expressed as average activity in minutes per

hour) of Nautilus Specimens No. 1, 2, and 6 at a range of tem-
peratures.

L) or darkness (D/D). This suggests that the subcycles
of activity are a basic or innate behavior, modified by
environmental factors (light and darkness) and a 24-h
endogenous periodicity.

Several workers have previously alluded to the short-
term periodicity, but did not comment on its significance.

TIME (MINUTES )

Figure 10

Frequency distributions of (A) duration of subcycle activity; (B)
period from commencement of one activity to the commencement
of the next, for the first three days of captivity of Nautzlus Spec-
imens No. 1, 2, 4, and 5.

Page 27

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Page 28

BIDDER (1962) stated that “from time to time an animal
becomes restless and swims about until a new resting place
is found” (presumably in the daytime), and HAYASAKA et
al. (1983) observed that, over two days of visual obser-
vations, Nautilus “moved from 15-20 minutes and rested
for 15-30 minutes repeatedly.”

The alternating swimming/resting behavior may be a
strategy for hunting and scavenging in the homogenous
environment of reef slopes where food is scarce and intra-
specific contacts infrequent. Nautilus is probably an op-
portunistic scavenger, evident from the gorged guts of the
trapped specimens, and a carnivore, indicated by the reg-
ular feeding on live shrimps in the aquarium. Although
underwater photographs showed a featureless soft bottom,
no Nautilus, and few potential prey organisms, bait rap-
idly attracts a wide variety of species (KING, 1983).

A pronounced nocturnal rhythm in an animal living at
a depth characterized by very low daylight intensity is
anomalous, particularly because the “‘pin-hole camera”
eye of Nautilus is far less sensitive to light, and of a far
lesser visual acuity, than any lensed eye (HURLEY et al.,
1978). Nautilus may hunt using its olfactory sense at night,
but its vision must be of some use during the daytime, a
time when it is largely inactive. Alternatively, the eyes
may be used for hunting caridian shrimps, one of the
dominant animals of the reef slopes; these species are
mainly nocturnal and release bioluminescent clouds when
disturbed (KING, 1983).

From the aquarium studies of the duration of swim-
ming and published estimates of velocity (average 0.17 m/
sec; range 0.10-0.25 m/sec; WARD et al., 1977), Nautilus
would swim about 1600 m per day (260 m in daylight,
370 m at dusk, 670 m at night, and 200 m at dawn). This
approximates some of the distances travelled by Carlson’s
telemetered N. belauensis (DUGDALE, 1982) which mi-
grated into shallower waters at night. However, because
of the distance to the nearest reef (6000 m) in this study,
it is improbable that Fijian N. pompilius migrate in the
same way.

ACKNOWLEDGMENTS

I would like to acknowledge the help of crew of the Uni-
versity of the South Pacific’s research vessel Nautilus, es-
pecially Richard Thaggard, Fiu Manueli, Euka Ninoki-
bau, and Mosese Sereinagata. Miss Marilyn Goulding
assisted with the analyses of records and Mrs. Sharan
with the type script. Professor W. Muntz of the Univer-
sity of Sterling helped design the activity recorder. I am
particularly grateful to Dr. M. King for distribution data,
and to Bruce Carlson for his personal communications.

Dr. B. Foster identified the epizoic barnacle. The equip-

The Veliger, Vol. 27, No. 1

ment was funded by French Aid and by a European Eco-
nomic Community grant. I am grateful to Dr. J. Gibbons
for proof-reading and Mrs. Sneh Lata Nath for typing
this manuscript.

LITERATURE CITED

BIDDER, A. M. 1962. Use of tentacles, swimming and buoy-
ancy in the pearly Nautilus. Nature 196:451-454.

DuGDALE, H. K. 1982. Chambered Nautilus Newsletter. 34:
1-3. Wilmington, Delaware.

Haven, N. 1977. The reproductive biology of Nautilus pom-
pilus in the Philippines. Mar. Biol. 42:177-184.

Hayasaka, S. et al. 1982. Field study on the habitat of Nautilus
in the environs of Cebu and Negros Islands, the Philippines.
Me. Kagoshima Univ. Res. Centre S. Pac., Vol. 3., 1:67-
137.

Hayasaka, S., Y. KAKINUMA, T. SAISHO, M. TABATA & N.
TAKESHI. 1983. Additional record of observation on Nau-
tilus pompilius in the aquarium of the Kamoike marine park,
Kagoshima, Japan. Kagoshima Univ. Res. Center S. Pac.,
Occas. Pap. No. 1:51-54.

Hur ey, A. C., G. D. LANGE & P. H. HaRTLINE. 1978. The
adjustable “pin-hole camera” eye of Nautilus. J. Exp. Zool.
205:37-44.

JECOLN (Japanese Expert Consultation on Living Nautilus).
1980. Nautilus macromphalus in captivity. Tokai University
Press, Japan.

KinGc, M. 1983. The ecology of deepwater caridean shrimps
(Crustacea: Decapoda: Caridea) near tropical Pacific is-
lands with particular emphasis on the relationships of life
history patterns to depth. Doctoral Thesis. The University
of the South Pacific, Suva, Fiji.

MikaMI, S. & T. OKUTANI. 1977. Preliminary observations
on maneuvering, feeding, copulating and spawning behav-
iors of Nautilus macromphalus in captivity. Jap. J. Malacol.
(Venus) 36:29-41.

SAUNDERS, B. 1981. The species of Nautilus and their distri-
bution. Veliger 24:8-17.

TANaBE, K. S., S. Hayasaka, T. SAISHO, A. SHINOMIYA & K.
AOKI. 1983. Morphologic variation of Nautilus pompilius
from the Philippines and Fiji islands. Pp. 9-21. Jn: Studies
of Nautilus pompilius and its associated fauna from Tanon
Strait, the Philippines. Occas. Pap. No. 1. Research Centre
for the South Pacific, Kagoshima University.

WarbD, P., L. GREENWALD & O. E. GREENWALD. 1980. The
buoyancy of the chambered Nautilus. Sci. Amer. 243:162-
175:

WarbD, P., R. STONE, G. WESTERMANN & A. MarTIN. 1977.
Notes on animal weight, cameral fluids, swimming speed,
and colour polymorphism of the cephalopod Nautilus pom-
pilius in the Fiji Islands. Paleobiology 3:377-388.

WILLEy, A. 1898-1902. Contributions to the natural history
of the pearly Nautilus in zoological results based on material
from New Britain, New Guinea, Loyalty Islands and else-
where collected during the years 1895, 1896 and 1897. Pt.
6:691-827. Cambridge Univ. Press: Cambridge.

The Veliger 27(1):29-36 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

Form and Function of the Radulae of

Pleurotomariid Gastropods

CAROLE S. HICKMAN

Department of Paleontology, University of California, Berkeley, California 94720

Abstract.

Detailed examination of the radulae of Pleurotomaria (Perotrochus) midas Bayer, 1965,

and P. (P.) quoyana Fischer & Bernardi, 1856, leads to new conclusions regarding the form and function
of the radula of the most primitive extant marine gastropods. A number of morphological features are
interpreted as mechanical adaptations for dealing with stress and efficient accommodation of teeth when
the radula is not in use. The terminal structures of the characteristic pleurotomariid “bristle tooth” are
found to lack the flexural stiffness that has been attributed to them. They are highly flexible and may
lie in tangled disarray after use in feeding. Independent evolution of similar teeth in Seila A. Adams,
1861, an unrelated mesogastropod that also feeds upon sponges, suggests that the morphology is not
ancient or phylogenetically constrained so much as it is functionally constrained. Independent lines of
evidence suggest that the radulae of living pleurotomariids offer few clues as to the radular morphology
of ancient marine gastropods and the primitive state of the molluscan radula.

INTRODUCTION

IT Is A matter of longstanding record that the living species
of pleurotomariid gastropods share a peculiar radular
morphology. Descriptions and line drawings (DALL, 1889;
BOUVIER & FISCHER, 1899; WOODWARD, 1901; BARNARD,
1963; AZUMA, 1964; FRETTER, 1964, 1966; HyMan, 1967;
BOUCHET & METIVIER, 1982) have emphasized the num-
bers of different kinds of teeth and, especially, the pres-
ence of numerous plates terminating in “brushes,” “tufts,”
or “bristles.” The details of form and the inferred function
of these teeth have not been considered closely, and the
terms “brush” and “bristle” may be inappropriate and
misleading in terms of functional and mechanical prop-
erties.

Use of the term “‘hystricoglossate” (HYMAN, 1976:236)
to describe the pleurotomariid radula emphasizes the dis-
tinctness from more typical rhipidoglossate archaeogastro-
pod radulae and reinforces the notion that the terminal
structures of the unique teeth are mechanically stiff or of
very limited flexibility. Data from gut contents and ob-
servations of the substrata from which specimens have
been taken or observed alive suggest that the animals feed
primarily by “grazing” on communities of encrusting in-
vertebrates, predominantly sponges (WOODWARD, 1901;
THIELE, 1935; YONGE, 1973; ROPER, personal commu-
nication, 1975; HICKMAN, 1976; ARAKAWA et al., 1978).
The bristle teeth have, therefore, been implicated as ad-
aptations for sponge feeding, and WOODWARD (1901) pro-

posed that the bristles might be used to remove “flesh”
from sponge spicules.

Examination of the radulae of two species over a range
of magnifications with conventional light microscopy and
scanning electron microscopy reveals a number of new
features and permits reevaluation of the pleurotomariid
radula. The primary objectives of this paper are to de-
scribe and illustrate the dentition, to reconsider the func-
tion of the “‘bristle teeth, and to consider the evolution
of this peculiar morphology in relationship to a close con-
vergence with structures in the radula of a sponge-feeding
cerithiopsid gastropod.

MATERIALS anp METHODS

Radulae were removed from preserved specimens by mid-
dorsal incision of the buccal cavity after observation of the
configuration of the radular ribbon and its relationship to
the odontophore. Radulae were cleaned in distilled water
after brief immersion in 10% sodium hydroxide to macer-
ate and remove extraneous proteinaceous material. Ma-
nipulation of the radulae under low power of a light mi-
croscope was used to establish topographic relationships
and the range of obvious and easily facilitated mechanical
movements of major fields of radular teeth. Radulae were
then divided into a series of segments, placed in vials num-
bered from anterior to posterior, and run through a graded
alcohol series from 70 to 100% to remove as much water

Page 30

The Veliger, Vol) 27-ionsl

as possible prior to drying for scanning electron micros-
copy.

Some segments were set aside for further examination
with light microscopy. The anteriormost segment and seg-
ments from the fully formed but unused mid portion of
the radula of each species were further cleaned in an ul-
trasonic cleaner and air dried. In addition, individual teeth
and clusters of teeth of different morphologies were cleaned
and air dried. Dried radular material was attached to
SEM stubs, coated with gold, and examined at low ac-
celerating voltages following procedures outlined by
HICKMAN (1981, 1983). Similar preparations were made
of radulae of related pleurotomariacean gastropods in the
families Scissurellidae and Haliotidae and of a sponge-
feeding cerithiopsid mesogastropod of greater phylogenet-
ic distance but similar feeding ecology.

RESULTS
Central Tooth Field

The major features of the pleurotomariid central tooth
field are illustrated in Figure 1. Figures 2 and 3 provide
comparable illustrations of the central tooth fields of the
other two families in the Pleurotomariacea, the Scissurel-
lidae and the Haliotidae. The major characteristics of the
pleurotomariid radula are as follows: (1) The teeth in the
central field are obscured in the flat-lying excised radula
by the larger and more well-developed marginal tooth
fields. (2) The teeth in a half row of the central field are
arranged with both cusps and bases in a characteristic
“V” shape. (3) The number of teeth in the central field
(as many as 59) is greater than in any known proso-
branch. (4) The central field is asymmetric, and there are
a number of distinctive features of the asymmetry: the
rachidian tooth is, itself, asymmetric (Figure 4); the teeth
within the central complex on either side of the rachidian

have their bases and cusps positioned asymmetrically rel-
ative to the mirror plane perpendicular to the plane of the
radular ribbon; and the skewing of the asymmetry may
be either to the left or the right. It is, for example, right-
skewed in Pleurotomaria (Perotrochus) quoyana and left-
skewed in Pleurotomaria (Perotrochus) midas (Figures 4
and 5, respectively). This form of asymmetry has evolved
independently in a number of prosobranch lineages, as
pointed out previously by HICKMAN (1982; 1984). (5)
There are three major types of teeth in the central field:
the asymmetric rachidian, hooded and-irregularly formed
inner laterals, and a set of more regularly developed outer
laterals that grade from a simple lamellar form to com-
plexly reinforced and cusped. These tooth types are de-
scribed more fully below.

Rachidian: The rachidian is a narrowly elongate struc-
ture that may be irregular in its development, its folded
appearance, and the sometimes ragged terminal end. It
generally has thin lateral folds that overlap similar lateral
folds on the two inner lateral teeth. Although the rachid-
ian tapers distally and may be folded into an acutely
pointed terminus, one would not call it a standard cusp,
nor is an obvious function suggested.

Inner laterals: The first three or four teeth on either side
of the rachidian are similar to the rachidian in their broad,
thin, and folded form. The inner pair is the largest, and
each has an irregularly enlarged hood-like distal termi-
nation that faces away from the rachidian and partially
enfolds and covers the terminations of the adjacent and
smaller inner lateral teeth. The remaining inner laterals
are progressively smaller and with less well-developed
hood-like terminations.

Outer laterals: The outer lateral teeth, which have been
referred to as “lamellate” by some authors (BARNARD,
1963; FRETTER, 1964, 1966; HYMAN, 1967:237), are com-

Explanation of Figures 1 to 9

Figure 1. Pleurotomaria (Perotrochus) quoyana Fischer & Ber-
nardi, 1856. Rachidian and lateral teeth. University of Miami,
Rosenstiel Institute of Marine Science, Gerda Sta. G-897. Bar =
200 um.

Figure 2. Haliotis rufescens Swainson, 1822. Rachidian, lateral,
and inner marginal teeth. University of California, Museum of
Paleontology Loc. UCMP R-3200. Bar = 200 um.

Figure 3. Scissurella crispata (Fleming, 1828). Rachidian, lateral,
and inner marginal teeth. R/V Oregon Sta. BMT-9. Bar = 40
um.

Figure 4. Pleurotomaria (P.) quoyana. Asymmetric rachidian and
skewed lateral tooth rows with right laterals situated farther
anterior than corresponding left laterals. Specimen same as Fig-
ure 1. Bar = 200 um.

Figure 5. Pleurotomaria (P.) midas Bayer, 1965. Asymmetric
rachidian and skewed lateral tooth rows with left laterals situ-

ated farther anterior than corresponding right laterals. Univer-
sity of Miami, Rosenstiel Institute of Marine Science, Gerda
Sta. G-10-16. Bar = 500 um. Figures 6 to 9 are from the same
radula.

Figure 6. Right outer lateral teeth in the region of transition
from lamellar plates (on left) to larger teeth with terminal and
subterminal denticles (on right). Bar = 400 wm.

Figure 7. Enlarged view of left outer lateral teeth oriented to
show ridges or thickenings on compressional surfaces of cusps.
Bar = 200 um.

Figure 8. Transition from lateral to marginal teeth. Right outer
lateral teeth are above and right inner marginals (sickle teeth)
are below. Bar = 400 um.

Figure 9. Transition from inner to outer marginals. Right inner
marginal sickle teeth are above and right outer marginal fila-
ment-tipped teeth are below. Bar = 400 um.

©. ©, Blickinen, 1064

Page 32

plex both in their row configuration and in the morpho-
logical gradation within rows. They are numerous (24-
26 per half row), and they are arrayed with their bases
and cusps forming a “V.” The first 18 to 20 teeth on the
inner segment of the “V” are relatively thin lamellar plates,
each with a small terminal bend or fold that might be
called a cusp. The plates are thickened on their inner
margins by enrolling of the edge. At the base, the partially
enrolled edge is expanded and attached to the radular
membrane in a configuration that should facilitate twist-
ing of the plate and allow more freedom in its movement.
The teeth along this segment of the “V” are aligned nearly
parallel to the longitudinal axis of the radula rather than
in more standard “transverse” rows. When the radula is
viewed in cross section, these teeth lie in topographic “‘gul-
lies,’ somewhat lower than the larger and more expanded
rachidian and inner laterals, and much lower than the
well-developed marginal complexes. At the base of the
“V” the outermost laterals begin to increase in length.
They are no longer thin, small lamelliform elements, but
become complexly reinforced in cross-sectional shape and
develop both a terminal and a subterminal pointed den-
ticle. The transition in this region of the radula is illus-
trated in Figure 6. On the convex or compressional surface
of the cusps, thickenings or “compressional ridges”
(HICKMAN, 1981) are evident (Figure 7). The form of
such teeth implies contact with the substratum during
feeding.

Marginal Tooth Fields

The major features of the pleurotomariid marginal tooth
fields are several. (1) The most massive and most mor-
phologically complex teeth are found in this portion of the
radula rather than in the central tooth field. (2) The cross-
sectional shape of the radula and its configuration in the
animal relative to the odontophore suggest that the mar-
ginal teeth, rather than the central complex, are the major
food-preparing structures. (3) The large inner marginal
teeth are accommodated in the folded radula in alternat-
ing, zipper-like fashion from one side of a row to another.

The Veliger,Vol=2Z7Aaiows

(4) Three major types of teeth occur in each of the mar-
ginal fields: hook-shaped sickle teeth, the filament-tipped
tangle teeth, and the paddle-shaped teeth. Each of these
types is described below.

Sickle teeth: The innermost marginal teeth are the most
formidable teeth in the pleurotomariid radula. Between
11 and 21 of these teeth occur in each half row. Other
authors have referred to them as “hooked” teeth (FRET-
TER, 1964, 1966) or “‘falcate plates” (BARNARD, 1963;
AZuUMA, 1964). The abrupt transition from outer laterals
to these teeth is illustrated in Figure 8. Although the term
“hooked” does accurately portray the fact that the teeth
are curved, it does not convey any notion of complex cross-
sectional shape. The term “sickle” is a better descriptor
not only of curvature, but also of the cross-sectional shape
and the distribution of materials. The terminology is not
intended to imply close similarity of function, however.

Filament-tipped teeth: The major portion of the mar-
ginal tooth complexes consists of so-called brush teeth
(FRETTER, 1964, 1966), bristle teeth (HYMAN, 1967), or
marginals with “tufts of bristles” (BARNARD, 1963). They
have been considered to be unique to the pleurotomariid
radula, and they are of a complex form that cannot be
described fully using light microscopy and low magnifi-
cation. There is also a heretofore undocumented discrep-
ancy between the appearance of the morphology before
and after use by the animal in feeding. The transition
from sickle teeth to filament-tipped teeth is illustrated in
Figure 9.

A typical unused but fully formed tooth from the middle
of a half row has two types of terminal structures (Figure
10): a group of numerous, thin filaments that lie parallel
to one another and, below them, a laterally flattened por-
tion that is deeply notched to form three prominent blunt
denticles. The innermost teeth within any half row tend
to be more weakly denticulate and lack the filaments, while
the outermost teeth lack denticles and the filaments are
greatly shortened and reduced in number. The terminal
end of a typical tooth is enlarged in Figure 10 to show
both types of structure. Figure 11 provides a proximal

Explanation of Figures 10 to 17

Figure 10. Pleurotomaria (Perotrochus) midas Bayer, 1965. En-
larged tip of a filament-tipped tooth showing filaments and sub-
terminal denticles. Bar = 40 um. This figure and Figures 11 to
15 are from the same radula illustrated in Figures 5 to 9.

Figure 11. Filament-tipped tooth showing region in which fil-
aments arise from tooth shaft in parallel series. Bar = 20 um.

Figure 12. Detail of the distal end of two filament clusters to
show branching of individual filaments. Bar = 10 wm.

Figure 13. Shafts and terminal filaments viewed from above to
show flattening of tooth shafts. Concave surfaces on left face
central axis of radula. Bar = 100 um.

Figure 14. Region of origination of filament clusters viewed from
above to show two series arising one on either side of a central
subcylindrical pit. Bar = 20 um.

Figure 15. Used filament-tipped teeth from the anterior end of
the radula. Bar = 100 um.

Figure 16. Pleurotomaria (P.) quoyana Fischer & Bernardi, 1856.
Used and worn teeth from anterior end of radula. Bar = 400
um.

Figure 17. Seila terebelloides (Hutton, 1873). Marginal teeth
showing convergent development of terminal filaments and sub-
terminal denticles. University of California, Museum of Paleon-
tology Loc. UCMP D-9044. Bar = 4 um.

Page 33

C. S. Hickman, 1984

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Page 34

detail of the pattern by which filaments arise in parallel
series from the flattened tooth shaft, while Figure 12 is a
detail of the distal end of two filament clusters, showing
that each filament may branch four or five times to form
a secondary cluster of terminally pointed filaments.

The entire shaft of the tooth is flattened and slightly
concavo-convex, as illustrated by viewing the teeth from
above (Figure 13). The concave surface is the surface
nearest the central axis of the radula, and it is the leading
edge in sweeping movements of the teeth. When the region
of origination of the filaments is viewed at even higher
magnification from above (Figure 14), two parallel series
of filaments and a central subcylindrical pit are evident.

Nothing in the appearance of these unworn teeth con-
travenes the traditional notion of bristliness or mechanical
stiffness. However, when they are manipulated while wet,
it is clear that they lack flexural stiffness, and examination
of teeth from the worn anterior end of the radula of Pleu-
rotomaria (Perotrochus) midas shows the filaments in a
tangled disarray that suggests more similarity to a mop
than to a broom (Figure 15). However, this particular
animal may, shortly before capture, have been radulating
a substrate that produced an unusual wear pattern. This
pattern has not been reported previously, and teeth from
the same region of the radula of a specimen of P. (P.)
quoyana, although showing evidence of flexibility and wear
(Figure 16), are not in the same tangled state.

Paddle-shaped teeth: The final 6 to 10 teeth in each half
row of the marginal complex are lacking in both filaments
and terminal denticulation. They are flattened and bluntly
paddle shaped. Flattened paddle-shaped teeth also occur
singly as outermost marginals in some gastropods in the
family Trochidae (HICKMAN, 1981), the prosobranch
family that appears to be most closely related to pleuro-
tomariids in a number of aspects of morphology and anat-
omy. The question of whether similarity of form is to be
interpreted as indicative of phylogenetic affinity or as con-
vergence related to function will be treated below.

The Radula of Sezla

The filament-tipped teeth of Pleurotomaria have been
considered unique among the Gastropoda. Although
BARNARD (1963) followed other authors in considering
this type of tooth to be characteristically pleurotomariid,
he noted a similar morphology portrayed in THIELE’s
(1929) illustration of the radula of the cerithiopsid genus
Seila A. Adams, 1861. Drawings in a recent monographic
treatment (MARSHALL, 1978) further reinforce the simi-
larity, and a scanning electron micrograph of the analo-
gous tooth from the radula of Sela terebelloides (Hutton,
1873) is provided for comparison in Figure 17.

DISCUSSION

Although pleurotomariid gastropods attract considerable
attention as collector’s items, as objects of great beauty,

The Veliger, Volz 27, Nom

and as “living fossils,” the foregoing detailed description
and illustration are not provided simply to add to the
mistique already surrounding these animals. Previously
unappreciated morphological features of the radulae of
living pleurotomariids provide a basis for reconsidering
the function of the morphology and the extent to which
morphology is a reflection of heritage from a Paleozoic
ancestor that had a primitive gastropod radula.

How Primitive is the Pleurotomariid Radula?

In its anatomy and basic shell form, living Pleuroto-
maria displays many features of gastropod organization
that are inferred to be primitive and that have been aban-
doned in the course of Phanerozoic gastropod evolution.
However, neither the long evolutionary history of pleu-
rotomarliids nor the conservative evolution of the shell jus-
tify concluding that the radula is conservative. In fact,
several reasons suggest that the radula is highly special-
ized and may bear little resemblance to the radulae of
ancient Paleozoic pleurotomariaceans.

The first reason for caution is the dissimilarity between
the radulae of large, living slit shells and those of scissu-
rellids and haliotids, members of the other two extant
pleurotomariacean families (Figures 1 to 3). The evolu-
tion of diverse radular morphology within the superfamily
shows no shared elements to suggest a unified primitive
superfamilial plan that has been resistant to change. The
second reason for caution is the difference in ecology sep-
arating Paleozoic and Mesozoic pleurotomariaceans from
living species (HICKMAN, 1976). The early fossil record
of slit shells occurs predominantly in shallow-water de-
posits, where shells are found in association with reef-
building and reef-inhabiting organisms. The living slit
shells, on the other hand, are restricted to relatively deep
water and rocky substrates. The encrusting invertebrates
with which Pleurotomaria has been observed and the pres-
ence of abundant sponge spicules in the gut suggest an
unusual form of “grazing” and source of nourishment.
The large number of teeth per transverse row in the rad-
ula of Pleurotomaria is frequently cited as a primitive fea-
ture (HYMAN, 1967:236). It can be generalized that proso-
branch evolution, as inferred from features other than the
radula, is accompanied by progressive reduction in the
numbers of teeth per row and the number of different
kinds of teeth in the radula. It would be unwarranted to
reject the possibility that some features of the Pleuroto-
maria radula are conservative; but it seems unlikely that,
in morphological detail, we are glimpsing a feeding organ
preserved from the Paleozoic era.

To What Extent Does Pleurotomariid Radular
Morphology Reflect Function?

If radular morphology in the Pleurotomariidae has not
been constrained closely by a plan that could not be
changed readily, we can assume that some of the variation

C. S. Hickman, 1984

and complex form has evolved either as mechanical alter-
ation of the apparatus or as solutions to problems of pre-
paring and ingesting particular kinds of food resources. It
is tempting to conclude that many of the unusual features
of the radula are adaptations for sponge feeding, but dem-
onstrations of how an apparatus works and how efficiently
it works go beyond the trivial observation that it does
work.

Without knowing anything about the properties of the
substrates on which the apparatus is used, little can be
concluded about the suitability of design for preparing and
gathering food. However, a number of features are subject
to mechanical interpretation (sensu HICKMAN, 1981).

The topological arrangement and the irregular and
underdeveloped morphology of elements in the central field
both suggest that the central field acts mechanically to
separate the marginal fields rather than to actively pre-
pare and gather food. The asymmetry of the central field
and its facilitation of alternatively interleaved accommo-
dation of the rows of large sickle-shaped inner marginals
further suggest a predominantly (not necessarily exclu-
sively) non-feeding function for the central complex. Fea-
tures such as compressional ridges on the outermost lat-
eral teeth and the pattern of distribution of materials in
the sickle-shaped teeth, as well as the concavo-convex cross-
sectional shape of the shafts of the filament-tipped teeth,
suggest mechanisms for dealing with different forms of
stress. They are similar in form to engineering solutions
to dealing with stress in man-made structures or imple-
ments.

Mechanical behavior of materials, such as the flexibility
of filaments in the radular elements previously called
“bristle” teeth, limits the possible range of functions.
Finding these filaments in tangled disarray in the ante-
riormost portion of the radula demonstrates their flexi-
bility and suggests that their function is not one requiring
great flexural stiffness.

The bristle-like appearance of the distal end of the new-
ly formed teeth provides a lesson in the analysis of mor-
phology and the constraints on form (HICKMAN, 1981).
The newly formed appearance of this particular mor-
phology may not be providing us with information about
phylogenetic or adaptive functional constraints so much
as it is providing information about constructional con-
straints on how the building material can be secreted.
Chitin can be secreted as separate fine filaments, but the
filaments will be secreted in parallel rather than in the
disarrayed configuration in which they are subsequently
used.

Morphological Convergence in
Pleurotomaria and Seila

The strongest argument for a functional interpretation
of the pleurotomariid filament-tipped teeth as adaptations
to sponge feeding and the strongest argument against their

Page 35

interpretation as phylogenetically constrained conserva-
tive morphology is the appearance of remarkably similar
teeth in the radula of sponge-feeding mesogastropods of
the genus Sei/a. These observations do not confirm how
the morphology is used, nor do they establish optimality
of design; but the inference that selection has been oper-
ative is strong.

CONCLUSIONS

Interpretation of the unusual radular morphology of liv-
ing pleurotomariid gastropods requires consideration of
the alternative constraints of the long and conservative
phylogenetic history of the superfamily, the mechanics of
an apparatus that moves and deals with stress, the eco-
logical factors involved in interaction of the apparatus with
specific feeding substrates, the limitations of the material
from which the apparatus is constructed, and the devel-
opmental limitations on how the material can be used to
form individual teeth with fine morphological detail.

Several lines of evidence suggest that the radula of Pleu-
rotomaria is not morphologically conservative or closely
constrained phylogenetically and that it should not be tak-
en as a representation of the primitive gastropod radula.
The evolutionary results of mechanical constraints are vis-
ible primarily in the distribution of materials in individual
teeth, particularly in cross-sectional shapes. Those teeth
constructed to deal most effectively with stress are situated
in the marginal tooth complexes rather than in the central
complex, although it is in the innermost portions of the
marginal complexes that most of the forces are apparently
generated.

Demonstration of the flexibility of the elements for-
merly referred to as “bristles” requires an alternative in-
terpretation of their mechanical function in feeding. Al-
though sponge material has been reported as common in
the gut contents of slit shells, it cannot be argued from
morphology alone that the flexible filaments represent an
adaptation for sponge feeding. The most powerful evi-
dence that morphology is related to sponge feeding comes
from the independent development of similar morphology
in an unrelated group of sponge-feeding mesogastropods.

ACKNOWLEDGMENTS

This paper is an outgrowth of a detailed study of archaeo-
gastropod radular morphology that has been supported by
National Science Foundation Grants DEB 77-14519 and
DEB 80-20992. I am grateful to G. Voss, Rosenstiel In-
stitute of Marine Sciences, University of Miami, for pro-
viding specimens of the two Pleurotomaria species for ex-
traction of radulae. I also thank B. Marshall, National
Museum of New Zealand, for providing radular material
of Sela for comparison. Scanning electron micrographs
were taken by the author in the Department of Anatomy,
University of California, San Francisco.

Page 36

LITERATURE CITED

ARAKAWA, K. Y., D. NAKANO, O. TSUKADA & T. HOSHINO.
1978. On fecal pellets and food habits of emperor’s slit
shell, Mikadotrochus hirasei (Pilsbry). Venus 37(3):116-120.

AzuMa, M. 1964. Notes on the radula of Perotrochus africanus
(Tomlin, 1948). Venus 22(4):350-355.

BERNARD, K. H. 1963. Notes on the animals Gyrina gigantea
(Lam.) and Pleurotomaria africana Tomlin. Proc. Malacol.
Soc. Lond. 35:155-158.

BoucHeEtT, P. & B. METIVIER. 1982. Living Pleurotomariidae
(Mollusca: Gastropoda) from the south Pacific. New Zea-
land J. Zool. 9:309-318.

Bouvier, E. L. & H. FISCHER. 1899. Reports on the results
of dredging ... in the Gulf of Mexico and the Caribbean
Sea, and on the east coast of the United States, 1877-1880,
by the U.S. Coast Survey Steamer “Blake”, ... 38. Etude
monographique des Pleurotomaires actuels. Bull. Mus.
Comp. Zool. Harvard 32:193-249.

Da._L, W. H. 1889. Reports on the results of dredging ... in
the Gulf of Mexico (1877-78) and in the Caribbean Sea
(1879-80), by the U.S. Coast Survey steamer “Blake”, ...
29. Report on the Mollusca. Part I].—Gastropoda and Sca-
phopoda. Bull. Mus. Comp. Zool. Harvard 18:1-492.

FRETTER, V. 1964. Observations on the anatomy of Mikado-
trochus amabilis Bayer. Bull. Mar. Sci. 14(1):172-184.

FRETTER, V. 1966. Biological investigations of the deep sea.
16. Observations on the anatomy of Perotrochus. Bull. Mar.
Sci. 16(3):603-614.

The Veliger, Voli 275Nom

HICKMAN, C. S. 1976. Pleurotomaria (Archaeogastropoda) in
the Eocene of the northeastern Pacific: a review of Cenozoic
biogeography and ecology of the genus. J. Paleont. 50(6):
1090-1102.

HIcKMAN, C. S. 1981. Gastropod radulae and the assessment
of form in evolutionary paleontology. Paleobiology 6(3):276-
204.

HICKMAN, C. S. 1982. Evolution and function of asymmetry
in the archaeogastropod radula. Veliger 23(3):189-194.
HICKMAN, C.S. 1983. Radular patterns, systematics, diversity,
and ecology of deep-sea limpets. Veliger 26(2):73-92.
HIcKMAN, C.S. 1984. Implications of radular tooth-row func-
tional integration for archaeogastropod systematics. Mala-

cologia 25(1):143-160.

Hyman, L. H. 1967. The invertebrates: Mollusca I. Apla-
cophora, Polyplacophora, Monoplacophora, Gastropoda.
McGraw-Hill Book Co.: New York. 792 pp.

MaRSHALL, B. A. 1978. Cerithiopsidae (Mollusca: Gastropo-
da) of New Zealand, and a provisional classification of the
family. New Zealand J. Zool. 5:47-120.

THIELE, J. 1929. Handbuch der Systematischen Weichtier-
kunde. Teil 1:1-376. Gustav Fischer: Jena.

THIELE, J. 1935. Handbuch der Systematischen Weichtier-
kunde. Teil 4:1023-1154. Gustav Fischer: Jena.

WoopwarbD, M. F. 1901. The anatomy of Pleurotomaria bey-
richu Hilg. Quart. J. Microscop. Sci. 44:215-268.

YONGE, C. M. 1973. Observation of the pleurotomariid En-
temnotrochus adansoniana in its natural habitat. Nature
241(5384):66-68.

The Veliger 27(1):37-53 (July 2, 1984)

THE VELIGER _
© CMS, Inc., 1984

The Pleurobranchidae
(Opisthobranchia: Notaspidea) of the Marshall
Islands, Central-West Pacific Ocean

by

R. C. WILLAN

Department of Zoology, University of Queensland, St. Lucia,
Brisbane, Queensland 4067, Australia

Abstract.

The following pleurobranchs were identified in a collection made by Mr. Scott Johnson

at Enewetak Atoll, Marshall Islands, central-west Pacific Ocean: Berthellina citrina (Ruppell & Leuck-
art, 1828); Pleurehdera haraldi Marcus & Marcus, 1970; Berthella pellucida (Pease, 1860); and Berthella
martenst (Pilsbry, 1896). This material represents significant range extensions for P. haraldi and B.
martensi, the former known previously from only the unique holotype and the latter “lost” for over a
century. The Pleurobranchidae shows much greater intraspecific variation in sculpture of the jaws’

elements than had previously been suspected.

INTRODUCTION

WHILE stationed at the Mid-Pacific Research Laboratory
on Enewetak Atoll, Marshall Islands, central-west Pacific
Ocean, Mr. Scott Johnson made extensive collections of
opisthobranchs. He generously sent me the side-gilled sea
slugs (Pleurobranchidae) he collected and photographed
on research sorties and longer residences between 1975
and 1983.

The collection, which totals 21 specimens and 14 color
transparencies, is interesting for two reasons. First, it pro-
vides material from the largely unsampled, tropical, cen-
tral Pacific region. Secondly, “large”? pleurobranchs—.e.,
species of Pleurobranchus in excess of 60 mm crawling
length as adults (such as P. grandis Pease, 1868, P. mamil-
latus Quoy & Gaimard, 1832, P. forskali Ruppell &
Leuckart, 1828, and P. peroniu Cuvier, 1804)—which
would have been expected to be present, are inexplicably
lacking, as are members of the subfamily Pleurobran-
chaeinae (e.g., Euselenops luniceps (Cuvier, 1817) and
Pleurobranchaea spp.).

The collection consists of the following four species, all
of which belong to the subfamily Pleurobranchinae:

Berthellina citrina (Riippell & Leuckart, 1828)
Pleurehdera haraldi Marcus & Marcus, 1970
Berthella pellucida (Pease, 1860)

Berthella martensi (Pilsbry, 1896).

Marcus & BurcH (1965) described 15 species of opis-
thobranchs from Enewetak Atoll collected by Dr. J. B.

Burch in 1960, but there were no pleurobranchs in that
collection.

TAXONOMY

Berthellina citrina

(Riippell & Leuckart, 1828)
(Figures 33 to 36)
Synonymy

BuRN (1962) has given an extensive synonymy for this wide-
spread Indo-Pacific species. WILLAN (1983) added three more
synonyms: Pleurobranchus cuviert Bergh, 1898; Berthella borneen-
sis Bergh, 1905; and Berthella minor Bergh, 1905. In addition,
it would seem that Pleurobranchus rufus Pease, 1860, with type
locality of Hawaii, is another synonym. The original description
(PEASE, 1860) gave a brief statement of external features only,
but the clues to its identity are there. Pleurobranchus rufus was
described as having a “smooth” body, “uniform vermilion” color
and a length of “1 inch.” No other Hawaiian pleurobranch
possesses all three characters. The presence of Berthellina citrina
in Hawaii has been verified by Kay (1979) and BERTSCH &
JOHNSON (1981).

I am not prepared to admit Berthellina engeli Gardiner, 1936,
into the synonymy of B. citrina as EDMUNDS & THOMPSON (1972)
have done.

Material

(1) 2 specimens (15, 14 mm long preserved) from under
dead coral, 1 m, Bokandretok Reef, Enewetak Atoll.
S. Johnson, 22 May 1982.

Page 38

(2) 2 color transparencies of a specimen (22 mm extended
crawling length), from under dead coral, 10 m, Sand
Island Pinnacle, Enewetak Atoll. S. Johnson, 19 July
1982.

(3) 2 specimens (16, 14 mm extended crawling length),
from under dead coral, 10 m, Sand Island Pinnacle
No. 2, Enewetak Atoll. S. Johnson, 5 March 1983.

Description

These Marshall Islands specimens agree well with Ber-
thellina citrina from elsewhere in the Pacific Ocean (see
WILLAN, 1983). The body is apricot with a very few white
specks; its transparency allows the reddish-golden shell to
be seen through the mantle anteriorly and the black diges-
tive gland posteriorly. The gill is longer and more narrow
than in Berthella species, and it has a smooth rachis. The
two Bokandretok Reef specimens had 22 and 18 pinnae
on the dorsal side of their gill raches respectively.

The radula is large, broad, and relatively elongate. For-
mulae are 85 x 186.0.186 and 75 x 130.0.130 respec-
tively. All the teeth are very elongate with 15 to 20 den-
ticles on the posterior face of the blade; the middle lateral
teeth are longest. The jaws (Figure 35) are relatively elon-
gate. The mandibular elements, when viewed at the sur-
face of the jaw (Figure 36), are noticeably elongate (60-
70 um long and 30-35 wm wide). Every one is smooth-
bladed.

The reproductive system is identical to that described
by BurN (1962) and WILLAN (1983) for Australian and
New Zealand specimens respectively.

Abundance

Mr. Johnson has seen 24 specimens of Berthellina ci-
trina at Enewetak Atoll. Most were beneath dead coral
blocks on lagoon pinnacles and on the seaward reef slope
at depths of 8 to 15 m. Two specimens have also been
observed at Kwajalein Atoll on a southern lagoon pinna-
cle.

Pleurehdera haraldi Marcus & Marcus, 1970
(Figures 1 to 5, 13 to 16, 19, and 20)
Synonymy

Pleurehdera haraldi Marcus & Marcus, 1970:158-160, figs.
8-10.

Material

(1) 1 specimen (40 mm extended crawling length) and
color transparency, from under dead coral, 3 m,
Enewetak Island, Enewetak Atoll. S. Johnson, 25 Nov.
1981.

(2) 1 specimen (14 mm extended crawling length), from
under dead coral, 4 m, Lagoonside, Enewetak Island,
Enewetak Atoll. S. Johnson, 11 Dec. 1981.

(3) 1 specimen (18 mm extended crawling length), from

The Veliger, Voly27-aNorsl

under dead coral, 5 m, Lagoonside, Enewetak Island,

Enewetak Atoll. S. Johnson, 19 May 1982.

2 color transparencies of a specimen (30 mm extended

crawling length), from under dead coral, 10 m, Ikuren

Island, Enewetak Atoll. S. Johnson, Sept. 1981.

(5) 3 specimens (25, 10, and 6 mm extended crawling
length), from under dead coral, 5 m, Lagoonside,
Enewetak Island, Enewetak Atoll. S. Johnson, 16 May
1982.

(6) 2 specimens (24, 20 mm extended crawling length),
from under dead coral, 5 m, Lagoonside, Enewetak
Island, Enewetak Atoll. S. Johnson, 14 July 1982.

(7) 2 specimens (both 22 mm extended crawling length)
and two color transparencies, from under dead coral,
2 m, Lujor Channel, Enewetak Atoll. S. Johnson,
Sept. 1981.

(4

WV

Mr. Johnson also kindly sent a transparency of a living
specimen from Hawaii (taken at night in a cave, 12 m,
Pupukea, Oahu, August 1980).

Description

Pleurehdera haraldi was previously known from only the
unique holotype that was preserved when described. A
full account is given here to relate the features of the living
animal and to present additional data pertinent to its im-
portant place in pleurobranch phylogeny (Marcus &
Marcus, 1970; WILLAN, 1983).

Living specimens can reach 40 mm in length when
extended and crawling actively. In this state (Figure 14)
the mantle is elongate-oval with lateral indentations. The
anterior mantle border is entire not emarginate. The oral
veil and rhinophores project in front of the anterior mar-
gin of the mantle (in fact the region of fusion of the rhi-
nophores is visible in advance of the mantle). The oral
veil is wide, its lateral edges diverging widely and being
noticeably tentaculate; the anterior margin is smooth and
gently undulating, without any indication of a mid-ante-
rior embayment. The rhinophores are short, broad, and
extend outwards rather than curving upwards.

In life the mantle’s appearance and texture resemble
those of Berthellina citrina. The mantle is soft and wrin-
kled, and extends beyond the foot a considerable distance
laterally and posteriorly—hence it covers the gill at all
times. Its edges are thin. The mantle’s surface is smooth,
yet magnification reveals numerous, tiny pores. The man-
tle has a characteristic texture in preserved animals: it is
rough and honeycombed (this honeycombing is visible
without magnification). The undersurface has a fibrous,
sponge-like texture. By contrast, the mantle of Berthellina
citrina, when preserved, is smooth and textured like velvet.

The living animal has a translucent body with a flush
of pale pink, fawn, or brown; when a specimen is resting,
the mantle becomes wrinkled and the folds between the
wrinkles are darker brown. The mantle’s translucency
permits the viscera (particularly the creamish-orange ovo-
testis and black digestive gland) to be seen easily. The

R. C. Willan, 1984

Page 39

i

Af, Salt
\ \

Explanation of Figures 1 to 5

Radula and jaws of Pleurehdera haraldi. Figure 1. Inner, middle, and outer lateral teeth. Figure 2. Entire right
jaw laid flat showing inner surface. Figures 3, 4, 5. Detail of mandibular elements from same region on inner face
of jaws of three different specimens. Figures 1, 3, 4, and 5 are drawn to same scale.

mantle has a scattering of small, intense, opaque white
spots over its entire surface and more numerous, smaller
gray speckles. Never was a differently colored marginal
zone present on the mantle. The rhinophores, oral veil,
and foot are translucent white or tan. The gill can be
either translucent white or whitish with faint brown
speckling. The genital apertures are white. Not one of the
specimens had been sufficiently well fixed to enable dis-
cernment of a pedal gland. Neither could the number of
gill pinnae be counted. However, the gill does have a
smooth rachis and is free from the body for approximately
half its length. The anus opens on the dorsal side of the
gill at the hind end of the basement membrane.

The shell is relatively small (one-third adult body length)
and exceedingly thin, although it is calcified. It is situated
anteriorly above the viscera as in Berthellina. One speci-
men had no shell. The shells of the other two Marshall
Islands specimens matched the description of MARCUS &
Marcus (1970).

The radula is nearly square. Radulae from three spec-
imens were stained, mounted, and examined. The Enewe-
tak Island specimen (collected 25 Nov. 1981) was 17 mm
long preserved; its radula measured 2.3 mm long by 1.8
mm wide when flattened on a slide; and its radular for-

mula was 59 x 73.0.73. The Enewetak Island specimen
(collected 11 Dec. 1981) was 12 mm long preserved; its
radula measured 1.6 by 1.2 mm; and its radular formula
was 54 Xx 60.0.60. Another Enewetak Island specimen
(collected 19 May 1982) was 11.5 mm long preserved; its
radula measured 1.9 by 1.7 mm; and its radular formula
was 54 X 67.0.67.

The innermost lateral teeth have a long basal plate and
a broad, curving, almost triangular main cusp (25 um in
vertical height) with a strong accessory denticle on the
outer face. The denticle, which is 9 um in vertical height,
arises from the main cusp, never directly from the basal
plate. The lateral teeth increase progressively in size, with
the fourth and successive teeth being larger and straighter
than the innermost three teeth. The middle laterals are
tall and erect (110 wm vertical height) and still have a
conspicuous denticle. The outermost laterals are narrow
and almost as tall as the middle laterals (95-110 um ver-
tical height); most clearly show a small denticle or pro-
jecting angle on the outer face. The presence of a single
accessory denticle on all teeth is one of the unique features
of Pleurehdera haraldi.

The jaws are ovate, rather small (each measuring 4.1
mm long by 1.7 mm wide in the 12 mm Enewetak Island

Page 40

specimen) and particularly thin along the dorsal margin
and posterior end (Figure 2). The mandibular elements
are cruciform, each having an elongate, parallel-sided blade
with a definite projection mid-way along the element (z.e.,
at the base of the blade). Two specimens had denticulate
blades (Figures 3, 4, 19, and 20) and one had smooth
blades on its mandibular elements (Figure 5) (see Re-
marks section under Berthella pellucida for a discussion of
the significance of smooth or denticulate blades). The
smooth-bladed elements are the same size (41-45 um ver-
tical height) as the denticulate elements (35-38 wm; 42-
46 wm). The two specimens with denticulate edges both
have elongate blades; the blades carry four to six denticles
in one, and six to seven denticles in the other specimen.
The denticles are narrow and forward-pointing and lack
apical thickenings. Because of the intraspecific variation
in mandibular element morphology, I have illustrated ele-
ments from each specimen (Figures 3 to 5).

The reproductive system of the only mature individual
(the 40 mm Enewetak Island specimen) was too badly
fixed to allow examination of any details.

Abundance

Mr. Johnson has recorded 18 specimens of Pleurehdera
haraldi from Enewetak Atoll. Most were observed on shal-
low inshore reefs beneath dead coral at depths of 3 to 6
m. One specimen was observed in a similar habitat at
Bikini Atoll. The single specimen from Hawaii (for which
only a slide was available) was found at a depth of 12 m.

Remarks

The recognition of Pleurehdera haraldi from the Mar-
shall Islands and Hawaii represents significant range ex-
tensions outwards from the Tuamoto Archipelago where
it was first described (MARCUS & Marcus, 1970), and
indicates that the species occurs throughout the tropical,
central Pacific Ocean.

The specimens examined by me agree well with the
holotype in most features (7.e., size, mantle, gill rachis,
shell, anal position, mandibular elements, and radula).
They differ only in color. The Marcuses’ specimen was
reported (on the basis of preserved material only) as black
all over (the darkly-pigmented epithelium was able to be
rubbed off) with a narrow, white marginal line. My spec-
imens, which were accompanied by color notes made from
life and by photographs, were translucent pale pink or
brown with white specks on the mantle. I cannot explain
the differences in color.

The present material allows an appraisal of the taxo-
nomic position of Pleurehdera within the Pleurobranchi-
dae. It is undoubtedly a unique genus because of char-
acters of its mantle, foot, shell, radula, and mandibular
elements. MARCUS & Marcus (1970:159) felt Pleurehdera
reduced the gap between the Pleurobranchinae and the
Pleurobranchaeinae because they found so much vari-

The Veliger, Vol. 27, No. 1

ability between the elements on the jaws of their one spec-
imen. While acknowledging that there is considerable in-
traspecific variability in the mandibular elements, even
more than originally appreciated (see Figures 3 to 5), I
find all the elements to be of the cruciform type (z.e.,
elongate in shape with lateral projections at the base of
the blade) rather than polygonal. As such, they do not
resemble the elements of Pleurobranchaea or Bathyberthel-
la. Thus, Pleurehdera should be firmly located in the
subfamily Pleurobranchinae. This is where the Marcuses
put it. In fact, it is closer to Berthellina than to Berthella,
Bathyberthella or Pleurobranchus because of its mantle tex-
ture, small anteriorly located shell, and denticulate radula
(with denticulation confined to one denticle per tooth).
Therefore, if one follows the BURN (1962) scheme of clas-
sification for the Pleurobranchidae (as explained by WIL-
LAN, 1983), Pleurehdera belongs to the berthelline group.

Berthella pellucida (Pease, 1860)
(Figures 6, 7, 17, 18, 29, 37 to 39, and 44)
Synonymy

Pleurobranchus pellucidus PEASE, 1860:24; PILsBRY, 1896:203,
204; BERGH, 1898:119; VaySSIERE, 1898:343; RIsBEC, 1928:
63-66, figs. 79-87; BABA, 1969:190, 191, fig. 1.

Berthella postrema BURN, 1962:140-142, pl. 1, fig. 2, pl. 2,
figs. 3-4, text figs. 1b, 2b, 4.

Berthella pellucida Pease; THOMPSON, 1970:188, fig. 8; Kay,
1979:443.

Material

(1) 2 specimens (16 mm, 12 mm extended crawling length)
and color transparency, from under dead coral, 2 m,
Enewetak Island, Enewetak Atoll. S. Johnson, 19 Sept.
1982.

(2) 1 specimen (14 mm extended crawling length) and
color transparency, from under dead coral, 8 m, inter-
island reef between Bokandretok and Madren Is-
lands, Enewetak Atoll. S. Johnson, 19 Nov. 1982.
(Subsequently referred to as Bokandretok/Madren
reef specimen.)

Description

The Marshall Islands lie within the tropical, central
Pacific range already known for Berthella pellucida, 1.e.
from Hawaii (PEASE, 1860; Kay, 1979) to New Caledonia
(RISBEC, 1928) and eastern Australia (BURN, 1962;
THOMPSON, 1970). I have additional records of this pleu-
robranch from Moreton Bay of southern Queensland (11
specimens, collected live), Cockburn Sound of Western
Australia (photograph courtesy N. Coleman), and Guam
(photograph courtesy R. Burn).

The three Marshall Islands specimens agree well with
other described Berthella pellucida. The 14 mm juvenile
from Bokandretok/Madren reef is depicted in Figure 17.
The mantle of B. pellucida is translucent and pale honey-

R. C. Willan, 1984

brown. Juveniles have a more-or-less distinct, central, viv-
id, opaque-white cross with white flecks and spots. Adults
have only a few, tiny white specks. The mantle is obvious-
ly covered with pores and glands over its entire surface,
imparting a texture that, in both the living and preserved
states, is honeycombed or “waffle-like” (RISBEC, 1928).
These pores are visible to the naked eye and are distinct
with even low magnification. The anterior edge of the
ample mantle is not emarginate; its edges are thin. The
gill never protrudes beyond the mantle margin, but it can
be seen easily through the transparent mantle. The Bo-
kandretok/Madren reef specimen had 12 pinnae on the
upper side of its gill, the rachis of which was smooth. The
anus opens at the hind end of the gill membrane.

The shell (Figure 29) is large, almost as big as the
mantle (7.e., four-fifths of the preserved body length), con-
vex, and auriculate. The posterior rim is higher than the
protoconch. Both the anterior and posterior margins are
evenly rounded. The left and right margins are nearly
parallel, and there is a distinct shoulder on the left side
of the shell. The sculpture is of smooth, concentric ridges
present both externally and internally. The shell appears
to have a continuous periostracal extension beyond the
calcified margin all round.

The radula is small, elongate, rectangular, and not
greatly expanded toward the growing end. Radulae from
two specimens were stained and mounted on slides; that
of the third was coated and mounted on a stub for SEM
study. The larger Enewetak Island specimen was 7.5 mm
long preserved; its radula measured 1.1 mm long by 0.8
mm wide when flattened on a slide; and its radular for-
mula was 57 x 55.0.55. The smaller Enewetak Island
specimen, whose radula was examined by SEM, was 6
mm long preserved, and its radular formula was 60 x
45.0.45. The Bokandretok/Madren reef specimen was 8
mm long preserved; its radula measured 1.6 mm by 1.0
mm; and its radular formula was 61 x 58.0.58 (sizes for
teeth given below relate to this radula).

The teeth are numerous and small. The innermost lat-
erals (Figure 37) have a small cusp that is sharply curved
toward the growing end of the radula. Innermost laterals
measure 12 wm in vertical height, and their broad basal
plates measure 20 um in length. Beyond the fifth lateral,
the middle laterals (Figure 38) increase progressively in
size, their cusps become broader and more erect (to 22 wm
high), and their basal plates are rectangular. Beyond two-
thirds of the way across the radula, the middle laterals
grade into outer laterals. The outer laterals (Figure 39)
are narrow and taller (up to 30 um high); some have a
hooked cusp and others are simple pegs; all have small,
oval basal plates (14 wm and shorter in length).

The jaws are small, each measuring 1.4 mm by 0.75
mm in the Bokandretok/Madren reef specimen, which
was 8 mm long preserved. Their shape is characteristic
(Figure 6); they are ovate, the inner margin being per-
fectly straight and the dorsal (or outer) margin evenly

Page 41

Re ee eC I |
Tmm

Figure 6

Both jaws of Berthella pellucida separated and laid flat showing
inner surface.

convex, describing a semicircle. The two jaws are attached
to each other anteriorly for approximately one-third of
their length. The mandibular elements are cruciform and
broad. All three specimens have smooth-sided blades
sometimes with thickened (either smooth or coarsely
sculptured) edges. The apices are not thickened. A short,
mid-central ridge is present on most of the elements. The
elements range in height from 38 to 40 um. They are
rather broad, measuring 20-25 wm between the lateral
projections. When examined with the SEM under high
magnification (x 5000), a fine, superficial, shagreened
sculpture was noted on all the elements (Figure 44).

The reproductive systems of all the Marshall Islands
specimens were immature and too poorly fixed to permit
examination of details. Therefore, I studied the reproduc-
tive systems of three specimens, collected by myself in
southern Queensland (Figure 7). In all animals I found
a receptaculum seminis diverging on a short duct directly
from the base of the bursa copulatrix. The presence of
two allosperm receptacles contradicts BURN’s (1962) state-
ment regarding the number of these organs. Also, and
most unusually for a species of Berthella, the vas deferens
was dilated and spongy for a distance along its mid-length.
This region comprises a distinct prostate gland. The peni-
al gland is tubular and elongate, and its blind end curves
around the base of the bursa copulatrix.

Abundance

Berthella pellucida is the commonest pleurobranch at
Enewetak Atoll. Mr. Johnson reports 24 recorded obser-
vations plus numerous unrecorded sightings. Nearly all of
the animals were on shallow, inshore, protected lagoon
reefs between the intertidal zone and 5 m. Berthella pel-
lucida has been seen throughout the year and is frequently
accompanied by its spawn.

Page 42

al.

The Veliger, Vol. 27, No. 1

Figure 7

Composite view of structure of reproductive organs of a mature Berthella pellucida. Abbreviations: amp., ampullar
region of hermaphrodite duct; al., albumen gland; b.c., bursa copulatrix; b.w., cut body wall; p.gl., penial gland;
pr., prostate gland; p.s., penial sheath; p.v.d., short proximal section of vas deferens; mu., mucus gland; r.s.,

receptaculum seminis.

Remarks

BuRN’s (1962) description of Berthella postrema is suf-
ficiently detailed to be sure that that taxon is a synonym
of B. pellucida. Twelve additional specimens from eastern
Australia confirm this view by the match of their appear-
ance, color, radula, and jaw details with Burn’s descrip-
tion. As noted above, however, I found differences in the
reproductive organs.

The most distinctive features of Berthella pellucida are
the following: its pale lemon-yellow color with overlay of
a white cross or specks; translucent mantle with porous
texture; 10 to 14 pinnae on a rather small gill; large,
auriculate shell covering the whole of the viscera; anus
opening at the hind end of the gill membrane; and broad
mandibular elements. The simple radular teeth are like
those of other Berthella species (e.g., B. ornata and B.
mediatas). The number of pinnae on the gill is less than
that for other Berthella species. Some details of the repro-
ductive system are typical of Berthella, 1.e., the origin of
the receptaculum seminis off the base of the bursa copu-
latrix far up the vagina. The enlarged prostatic section of
the vas deferens is atypical of Berthella.

The mandibular elements are smooth-bladed in all three

Marshall Islands specimens, yet descriptions of Berthella
pellucida from elsewhere cite them as denticulate (BURN,
1962; THOMPSON, 1970; personal observations of four
southern Queensland specimens). This anomaly in im-
portant details of mandibular sculpture led me to review
the literature closely, and I discovered no less than eight
species of pleurobranchs that sometimes possess or some-
times lack denticles to the blades on their mandibular
elements. These data are crucial for their bearing on pleu-
robranch systematics, particularly for the interpretation
of species, so I have listed all the examples.

Berthella tupala Marcus, 1957

Reported to have two or three rounded cusps (MARCUS,
1957), zero to five denticles (MARCUS & MARCUS, 1967),
or smooth blades (BERTSCH, 1975).

Berthella californica Dall, 1900

Reported to have entirely smooth blades (BERGH, 1905;
MacFARLAND, 1966). MACFARLAND (1966) segregated,
as a new subspecies (denticulatus), animals with one to
five, strong, pointed denticles on their elements; yet, den-
ticulatus does not differ in other external or internal fea-
tures. MACFARLAND remarked (1966:84): “In all external

R. C. Willan, 1984

characters it [Pleurobranchus californicus denticulatus| co-
incides with Pleurobranchus californicus herein described.”

Berthella ornata (Cheeseman, 1878)

Mandibular blades are normally smooth, but rarely a
weak denticle is present on the side of the blade about
half way between the lateral projection and apex (WIL-
LAN, 1975, 1983).

Berthella mediatas Burn, 1962

Reported to have three to five strong, coarse denticles
(BERGH, 1900; WILLAN, 1975, 1983) or to have edges of
blades coarsely roughened, but not noticeably denticulate
(BURN, 1962). Two specimens from New Zealand’s South
Island had irregularly roughened, but certainly not den-
ticulate, blades.

Berthella pellucida (Pease, 1860)

Reported to have two or three strong denticles (RISBEC,
1928; BURN, 1962; present observations of four southern
Queensland specimens) or two short denticles on blades
(THompsoN, 1970). The Marshall Islands specimens de-
scribed herein had smooth-sided blades (Figure 44).

Berthella martensi (Pilsbry, 1896)

VAYSSIERE (1898:300) reported two to three small den-
ticles on the blades of the mandibular elements. The ele-
ments of all seven specimens I examined had smooth blades
(Figure 27), except for one jaw that had a few rows of
elements near the outer margin with one to three irregular
denticles flanking the cusp (Figure 28).

Pleurehdera haraldi Marcus & Marcus, 1970

Marcus & Marcus (1970) noted and illustrated the
variation between elements depending on their position on
the jaw. Their illustrations show four to ten denticles,
which are coarse and strong where there are few, or fine
where there are many denticles on the blades. Two of the
Marshall Islands specimens reported herein had dentic-
ulate blades (Figures 3 and 4) and one had smooth blades
(Figure 5).

Berthellina citrina (Ruppell & Leuckart, 1828)

Usually reported to have smooth blades (e.g., BURN,
1962; WILLAN, 1983), THOMPSON (1970) found one or
two short, pointed denticles on the blades. WILLAN (1983)
gave a SEM of mandibular elements possessing a single,
asymmetric cusp.

These eight examples confirm the great degree of in-
traspecific variation in the sculpture of mandibular ele-
ments in the Pleurobranchidae. Until now sculptural de-
tails have been interpreted as having high diagnostic
significance (e.g., BURN, 1962; MACFARLAND, 1966; WIL-
LAN, 1983). While intra-individual variation in sculpture
between elements on one particular jaw has been ac-
knowledged (O’ DONOGHUE, 1929:58; PRUVOT-FOL, 1934:
32; Marcus & Marcus, 1970:159), the potential range
of intraspecific variation in sculpture (from completely
smooth to strongly denticulate) in some “‘berthelline”

Page 43

species has never been suspected. The variation appears
to be continuous rather than discontinuous. Such variation
cannot be ontogenetic (Marcus & Marcus, 1958:21,
MACFARLAND, 1966:79, pl. 14, figs. 10-14, and BERTSCH,
1975, have described the development of pleurobranch
mandibular elements) nor geographic (see the data for
Berthella mediatas and Pleurehdera haraldi presented above);
nor can it be due to a possible artifact or error of prepa-
ration or observation on the anatomist’s part. The conclu-
sion seems inescapable that many of the small ‘‘berthel-
line” pleurobranchs can have blades to their mandibular
elements that are sometimes smooth or sometimes dentic-
ulate. Therefore, all researchers should give sculptural
details of the mandibular elements less weighting when
they are assessing their species against others.

Berthella martensi (Pilsbry, 1896)
(Figures 8 to 12, 21 to 28, 30 to 32, 40 to 42, and 44)
Synonymy

Pleurobranchus scutatus MARTENS in MOsIus, 1880:309, pl. 21,
fig. 8 (non Pleurobranchus scutatus Forbes, 1844).

Bouvieria scutata MARTENS in MOsIus; VAYSSIERE, 1896:123,
pl. 5, figs. 16-18; VayssIERE, 1898:297, pl. 18, figs. 44-49
(non Pleurobranchus scutatus Forbes, 1844).

Gymnotoplax martens: PILSBRY, 1896:211, pl. 48, figs. 34-35;
Marcus, 1977:418; WILLAN, 1978:339, 342.

Material

(1) 1 specimen (18 mm extended crawling length) and
color transparency, from under dead coral, 5 m, La-
goonside, Enewetak Island, Enewetak Atoll. L.
Boucher, 26 Jan. 1982.

(2) 1 specimen (25 mm extended crawling length), from
under dead coral, 10 m, Jedrol Island, Enewetak
Atoll. S. Johnson, 23 April 1982.

(3) 1 specimen (12 mm extended crawling length) and

color transparency, from under dead coral, 10 m, No

Bull Pinnacle Number 2, Enewetak Atoll. S. John-

son, 27 Oct. 1982.

1 specimen (30 mm extended crawling length) and

color transparency, from under dead coral, 4 m, No

Bull Pinnacle Number 2, Enewetak Atoll. S. John-

son, 27 Oct. 1982.

(5) 1 color transparency of a specimen (23 mm extended

crawling length), from 4m, Enewetak Island, Enewe-

tak Atoll. S. Johnson, 10 Sept. 1981.

1 color transparency of a specimen (27 mm extended

crawling length), from 2 m, Jinimi Island, Enewetak

Atoll. S. Johnson, 23 July 1981.

(4

WH

(6

WN

Mr. Johnson also kindly sent two specimens from Ha-
waii. They were found crawling in a cave at night, 10 m,
Puako, Hawaii, 24 Oct. 1980. Mr. Johnson supplied me
with data for sightings of 18 additional live specimens
from Hawaii, all at night in 8 to 10 m of water (photo-
graphs of two of these were inspected).

Page 44

I have personally collected two specimens of Berthella
martensi, at Lizard Island, northern Queensland (1 spec-
imen, 9 Oct. 1982) and N.W. of Point Lookout, southern
Queensland (1 specimen, 25 March 1983). Additional
photographic records are available from the following lo-
calities: Mana Island, Fiji, 1979 (courtesy of Dr. P.
Morse); and Fremantle, Western Australia, 1976 (cour-
tesy of Mr. N. Coleman). An excellent color photograph
of a specimen from Lizard Island, northern Queensland,
has been published by KUITER (1982:37). JOHNSON (1982)
has published a photograph of Berthella martens: from
Hawaii.

Description

The following full account is necessary because Ber-
thella martensi has not been rediscovered since it was first
described on the basis of three, apparently juvenile spec-
imens over a century ago. Then it was called Pleurobran-
chus scutatus Martens in Mobius, 1880, but that taxon
was preoccupied by Pleurobranchus scutatus Forbes, 1844,
and so the specific name was changed to martensi (PILSBRY,
1896). VAYSSIERE (1898) re-examined the original speci-
men.

Berthella martensi can attain 73 mm in extended crawl-
ing length, although 30 to 60 mm is usually for mature
adults. The body is elongate-oval, smooth, and flat on top.
The oral veil and rhinophores are visible anteriorly, but
the tail is usually covered by the large, overhanging man-
tle when the animal is crawling actively; the gill is never
visible. The foot is long and parallel-sided, and the tail is
almost pointed. There is a large and conspicuous, semi-
circular mucus groove anteriorly, and this extends to the
squarish, anterior foot corners that are visible in front of
the mantle in actively crawling animals.

The mantle is soft (almost gelatinous), smooth or slight-
ly wrinkled (but never pustulose or papillate), very wide
with thin margins, and nearly circular. Anteriorly it bears
a deep cleft that extends rearwards about one-seventh of
the mantle’s full length. This cleft reveals the point of
fusion of the rhinophores. The mantle’s margins are par-
allel and the posterior edge is broadly rounded. The man-
tle consists of three large, readily autotomized (see Re-
marks section) lobes that are fused but distinguishable on
the surface by “preformed shear zones,” z.e., distinct, nar-
row, slightly impressed, radial lines at the zones of con-
tact. There are two symmetrical antero-lateral lobes that
meet in the midline just behind the rhinophores, and a
single posterior lobe. Each antero-lateral lobe meets the
posterior lobe postero-dorsally about one-third of the dis-
tance from the tail to the head. Mid-dorsally between the
three lobes is a smaller, triangular (or “‘bell-shaped’’) sec-
tion that is never autotomized.

The oral veil is trapezoidal and relatively short; its an-
terior margin is simple and straight. Active specimens
sometimes show a weak mid-anterior embayment, but the

The Veliger, Vol. 27, No. 1

margin is never sinuous. Both the upper and lower sur-
faces of the oral veil are smooth.

The rhinophores are moderately tall. They arise from
a common base which is visible anteriorly when B. mar-
tensi is crawling. The tips of the rhinophores do not “pul-
sate” in life like those of some Pleurobranchus species.

The gill has a smooth rachis and a mean of 16.25 (range
13-19; N = 4) pinnae on the upper side. The anus opens
at the hind end of the gill’s suspensory membrane.

Coloration is variable (Figures 21 to 25), but now that
I have seen 14 specimens I believe the limits of variation
can be ascertained and described. The upper body and
mantle have a ground color of pale ochre, pale reddish-
brown, light brown, amber, or yellowish- or creamish-
brown, and there is an overlay of few or many irregular,
chocolate or dark purplish-brown spots. These spots are
usually small and evenly spaced (Figures 21, 22, and 24),
but there can also be only a few large ones (Figure 25;
KUITER, 1982) or none at all (Figure 23). With magni-
fication, the brown spots resolve into dense aggregations
of purple-brown flecks. The margins of the central tri-
angle on the mantle usually have a chocolate line, and
there is always a longitudinal streak of the same color
mid-dorsally on the tail (Figures 23 and 25). The shear
zones on the mantle are sometimes indicated by brown
lines. Other parts of the body that have wide or narrow
brown lines are the antero-lateral corners and anterior
margin of the oral veil, the rhinophores (but not the com-
mon rhinophoral base), the anterior mucus groove, the
foot, and the gill rachis. A thin brown line extends con-
tinuously all round the body at the junction of the foot
and mantle. A second line, which is stronger and darker,
extends on the right side backwards from the corner of
the oral veil to the start of the gill; in doing so it passes
above the genital apertures. On the left side an identical
line extends about one-third of the way along the body.
These two lateral lines and the mid-dorsal, longitudinal
tail streak are the markings that are most consistent on
all specimens. The brown pigment is easily rubbed off,
even in living specimens. The body tissues are quite trans-
lucent; for example, the brown gill rachis is visible through
the side of the mantle when the mantle is pressed against
the body. The shell and viscera are usually faintly visible
beneath the mantle. The foot sole is usually milky-white
or pale amber in contrast to the mantle and upper body.

Berthella martens: is a lethargic pleurobranch. It is highly
photonegative and hides during the day beneath ledges
and boulders. Mr. Johnson informs me that in Hawaii
he has observed 18 specimens that were actively crawling
at night. The mantle can produce a white fluid when B.
martensi is disturbed. The mantle lobes are autotomized
very readily by rough handling or preservation (see Re-
marks section for further discussion).

The shell (Figures 30 to 32) that lies beneath the tri-
angular area in the center of the mantle is small, about
one-third of the adult body length. The shell’s protoconch

R. C. Willan, 1984

Page 45

Explanation of Figures 8 to 12

Jaws and reproductive system of Berthella martenst. Figure 8. Both jaws separated and laid flat showing inner
surface. Figure 9. Detail of nidamental glands. Figure 10. Detail of seminal receptacles. Figure 11. Detail of
structures associated with distal section of vas deferens and penis; penial sheath cut longitudinally. Figure 12.
Composite view of structure of reproductive organs of a mature individual (penial sheath removed). Abbreviations
used in Figures 9 to 12: al., albumen gland; amp., ampullar region of hermaphrodite duct; b.c., bursa copulatrix;
b.w., cut body wall; d.v.d., distal section of vas deferens; g.pr., genital protuberance; mu., mucus gland; p., penis;
p-gl., penial gland; p.s., penial sheath; r.s., receptaculum seminis; v., vagina.

lies beneath the rear of the central area, and its abapical
margin does not quite extend to the front of the central
area. Thus, the shell covers the anterior section of the
digestive gland, ovotestis, and pericardium. It is slender,
elongate, and calcified. The apex is narrow and the pro-
toconch elevated; the posterior rim is always lower than
the protoconch, and the outer lip slopes sharply away
posteriorly without any flare (Figures 31 and 32). The
right and left margins are nearly parallel. The abapical

margin is evenly rounded, and not truncated. The abapi-
cal section is evenly convex, not flattened as in Berthellina
citrina. The columellar slope on the left side (when the
shell is dorsal) is almost flat, not steep. The only sculpture
consists of undulating, concentric ridges (Figure 30). The
shell is glossy because of an entire periostracal layer; the
periostracum does not extend beyond the margins. The
shell is amber. The shell drawn by VAYSSIERE (1898:pl.
18, fig. 45), which was 6 mm long by 3 mm wide, matches

Page 46

the Veliger Volk 27 Niomsl

Explanation of Figures 13 to 20

Figure 13. Pleurehdera haraldi; length 40 mm. From 3 m,
Enewetak Island, Enewetak Atoll, 19 Sept. 1981. Photograph:
S. Johnson.

Figure 14. Pleurehdera haraldi; length 22 mm. From 2 m, Lujor
Island channel, Enewetak Atoll, Sept. 1981. Photograph: S.
Johnson.

Figure 15. Pleurehdera haraldi; length 28 mm. From 3 m,
Enewetak Island, Enewetak Atoll, Sept. 1981. Photograph: S.
Johnson.

Figure 16. Pleurehdera haraldi; length 22 mm. From 12 m, Pu-
pukea, Oahu Island, Hawaii, August 1980. Photograph: S.
Johnson.

Figure 17. Berthella pellucida; length 14 mm. From 8 m, Bo-
kandretok/Madren Reef, Enewetak Atoll, 19 Nov. 1982. Pho-
tograph: S. Johnson.

Figure 18. Berthella pellucida; length 22 mm. From 0 m, Myora,
Moreton Bay, southern Queensland, 21 Sept. 1981. Photograph:
R. C. Willan.

Figure 19. Photomicrograph of mandibular elements of Pleureh-
dera haraldi; from inner face of jaw. Specimen from 3 m, Enewe-
tak Atoll, 23 Nov. 1981. Bar = 40 um.

Figure 20. Photomicrograph of mandibular elements of Pleureh-
dera haraldi; from inner face of same jaw as Figure 19. Bar =
40 um.

Explanation of Figures 21 to 28

Figure 21. Berthella martensi; length 28 mm. From 2 m, Jinimi
Island, Enewetak Atoll, Sept. 1981. Photograph: S$. Johnson.

Figure 22. Berthella martensi; length 23 mm. From 4 m, Enewe-
tak Island, Enewetak Atoll, Sept. 1981. Photograph: S. Johnson.

Figure 23. Berthella martensi; length 36 mm. From 8 m, Puako,
Hawaii Island, Hawaii, Aug. 1980. Photograph: S. Johnson.

Figure 24. Berthella martensi; length 39 mm. From 8 m, N.W.
of Point Lookout, North Stradbroke Island, southern Queens-
land, 25 March 1983. Photograph: R. C. Willan.

Figure 25. Berthella martensi; length 73 mm. From 8 m, N.W.
coast of Lizard Island, northern Queensland, 9 Oct. 1982. Pho-
tograph: R. C. Willan.

Figure 26. Enlarged reproduction of VAYSSIERE’s (1898, pl. 18,
fig. 44) illustration of a paratype of Pleurobranchus scutatus Mar-
tens in Mdbius, 1880; length of actual preserved specimen 13.5
mm.

Figure 27. Photomicrograph of mandibular elements of Berthella
martensi, showing typical elements from inner face of jaw. Spec-
imen from 10 m, Jedrol Island, Enewetak Atoll. Bar = 50 um.

Figure 28. Photomicrograph of mandibular elements of Berthella
martenst; from inner face of jaw. Specimen from 10 m, No Bull
Pinnacle Number 2, Enewetak Atoll. Area depicted is near dor-
sal margin showing weak denticles flanking main cusp. Bar =
50 um.

Explanation of Figures 29 to 36

Figure 29. External (right) and internal (left) views of shell of
Berthella pellucida; length 6.4 mm xX width 4.1 mm. Specimen
from 18 m, Bokandretok/Madren reef, Enewetak Atoll, 19 Nov.
1982; extended crawling length 14 mm.

Figure 30. External (right) and internal (left) views of shell of
Berthella martensi; length 11.2 mm x width 4.7 mm. Specimen
from 10 m, Puako, Hawaii, 24 Oct. 1980; preserved length 24
mm.

Figure 31. External (right) and internal (left) views of shell of
juvenile Berthella martensi; length 5.5 mm x width 3.0 mm.
Specimen from 10 m, No Bull Pinnacle Number 2, Enewetak
Atoll, 30 May 1982; extended crawling length 12 mm.

Figure 32. External (right) and internal (left) views of shell of

Berthella martensi; length 10.6 mm x width 4.7 mm. Specimen
from 10 m, Jedrol Island, Enewetak Atoll, 23 April 1982; ex-
tended crawling length 25 mm.

Figure 33. SEM of middle lateral teeth from radula of Berthel-
lina citrina. Specimen from 1 m, Bokandretok Reef, Enewetak
Island, 22 May 1982. Bar = 40 um.

Figure 34. SEM of inner lateral teeth from same radula of
Berthellina citrina as shown in Figure 33. Bar = 20 um.

Figure 35. SEM of entire right jaw laid flat showing inner
surface. Bar = 1 mm.

Figure 36. SEM showing detail of mandibular elements from
inner surface of same jaw as shown in Figure 35. Bar = 40 um.

Explanation of Figures 37 to 44

Figure 37. SEM of midline (right) and inner lateral teeth from
radula of Berthella pellucida. Specimen from 2 m, Enewetak Is-
land, 19 Sept. 1982. Bar = 20 um.

Figure 38. SEM of middle lateral teeth from same radula of
Berthella pellucida as shown in Figure 37. Bar = 20 um.

Figure 39. SEM of outer lateral teeth close to edge of same
radula of Berthella pellucida as shown in Figure 37. Bar = 20
pm.

Figure 40. SEM of middle lateral teeth from radula of Berthella

martensi. Specimen from 10 m, Puako, Hawaii, 24 Oct. 1980.
Bar = 20 um.

Figure 41. SEM showing detail of middle lateral teeth from
same radula of Berthella martensi as shown in Figure 40. Bar =
20 um.

Figure 42. SEM of outermost lateral teeth from same radula of
Berthella martensi as shown in Figure 40. Bar = 20 um.

Figure 43. SEM showing detail of mandibular elements from
inner surface of jaw of same Berthella martens: as shown in
Figure 40. Bar = 40 um.

Figure 44. SEM showing high magnification of mandibular ele-
ment from inner surface of jaw of Berthella pellucida. Specimen
from 2 m, Enewetak Island, 19 Sept. 1982. Note shagreened
texture. Bar = 4 um.

R. C. Willan, 1984

The Veliger, Vol. 27, No. 1

Page 48

Page 49

R. C. Willan, 1984

The Veliger, Vol. 27, No.

R. C. Willan, 1984

closely that of the smaller No Bull Pinnacle specimen
(Figure 31).

Radulae from three Marshall Islands, two Australian
and one Hawaiian specimen were stained and mounted
on slides; the radula of the second Hawaiian specimen
was coated and mounted on a stub for SEM study. One
Hawaiian specimen was 24 mm long preserved; its radula
measured 3.0 mm long by 3.0 mm wide when flattened
on a slide; and its radular formula was 104 x 186.0.186
(sizes of teeth given below relate to this radula). The rad-
ular formula for the second Hawaiian specimen, which
was a similar length, was 93 xX 158.0.158. The larger No
Bull Pinnacle specimen was 16 mm long preserved; its
radula measured 2.0 by 2.8 mm; and its radular formula
was 82 x 124.0.124. The smaller No Bull Pinnacle spec-
imen was 8 mm long preserved; its radula measured 1.9
by 1.3 mm; and its radular formula was 57 x 92.0.92.
The Enewetak Island specimen was 15.5 mm long pre-
served; its radula measured 2.0 by 1.5 mm; and its radular
formula was 66 x 84.0.84. A general formula for adult
B. martensi is 82-104 x 124-186.0.124-186.

The buccal mass is particularly large and consists of
two jaws with a small radular sac postero-ventrally be-
tween them. The floor of the buccal mass between the
jaws is slightly concave. The innermost lateral teeth (Fig-
ure 40) have relatively narrow blades, much-recurved
cusps, and elongate basal plates; they measure 16 wm in
vertical height, and their basal plates measure 22 wm in
length. The middle laterals (Figure 41) are somewhat
larger (24-30 um in vertical height) and equally curved.
The outermost laterals (Figure 42) have tall, narrow,
curved (not erect or peg-like) blades; they measure about
30 um in vertical height.

The jaws (Figure 8) are particularly large and nearly
round; the ventral margin is straight, the anterior margin
is subtruncate, and the dorsal and posterior margins are
convex and evenly rounded. The height (2.9 mm for a
Hawaiian specimen) is a little greater than the width of
a single jaw (2.5 mm). The mandibular elements consti-
tuting the jaws are cruciform with narrow blades, con-
spicuous lateral projections, and broad bases. The ele-
ments of all seven sets of jaws I examined were smooth
(Figure 27), except for some elements eight to ten rows
in from the dorsal margin of the larger No Bull Pinnacle
specimen, which had one to three, irregular denticles
flanking the cusp (Figure 28). The Hawaiian specimen
examined with the SEM (Figure 43) had thickened mar-
gins, and both the No Bull Pinnacle specimens had elon-
gate, thickened apices to their blades. The height of the
elements from the Hawaiian specimen whose jaw dimen-
sions are given above is 75-80 um; the width between
projections is 60-62 wm; and the width across the base of
an element is 40-45 yum.

Reproductive systems were dissected from the Jedrol
Island specimen (the other Marshall Islands specimens
were badly preserved), the two Hawaiian specimens, and
the two Queensland specimens. The reproductive system

Page 51

is typical of the genus Berthella and is shown in Figures
9 to 12. Significant details are as follows. A genital papilla
is present on the preserved specimens; it is a relatively
large, flat-topped mound; and it bears small pustules over
its surface. The penis is relatively small, simple, and con-
ical. The penial gland arises far back on the vas deferens.
The vas deferens is not expanded into a prostate gland.
The receptaculum seminis arises high up the vagina (ap-
proximately two-thirds of the distance to the bursa cop-
ulatrix).

Berthella martensi lays a flaccid, white spawn coil. Ova
measuring 75-95 wm occur singly in capsules (up to 190
um diameter) that are loosely coiled in cylinders within
the spawn. Approximately 315 ova make up a single coil.
Two egg masses laid in the laboratory by a 40 mm
Enewetak Island specimen on the same day contained
about 55,000 and 40,000 ova respectively (L. Boucher,
personal communication, 1983).

Abundance

Mr. Johnson recorded 17 specimens of Berthella mar-
tens. between July 1981 and February 1983. All were
found beneath dead coral at depths ranging from 2 to 12
m. The species occurs in clean-water habitats, being found
in both lagoonal situations and on inter-island reefs. Mr.
Johnson has observed the different color forms tending to
pair with their own color form; of four copulating pairs
seen, only one was mixed.

Remarks

One of the most characteristic behaviors of Berthella
martensi is that of mantle autotomy. The mantle breaks
along any two of the “preformed shear zones” and any of
the three lobes can be autotomized. The central triangular
area is never shed. Of the three type specimens, one had
evidently autotomized the anterior left lobe and another
had autotomized the anterior right lobe. My specimen
from Lizard Island, Queensland, had autotomized the
posterior lobe, and this had evidently regrown but not
fused with the anterior lobes, nor had the dark spots been
reproduced. Among the Marshall Islands material, the
larger No Bull Pinnacle specimen and the Jedrol Island
specimen had autotomized both the anterior lobes; the
Enewetak Island specimen and smaller No Bull Pinnacle
specimen both had split their mantles along the three
“shear” zones, but none of the lobes had been fully au-
totomized. One of the Hawaiian specimens had autoto-
mized the posterior lobe and the other both the anterior
lobes. On being narcotized, my specimen from southern
Queensland autotomized its anterior right lobe, and then
it resembled perfectly VAYSSIERE’s diagram (1898:pl. 18,
fig. 44), reproduced here in Figure 26.

Since Berthella martensi never autotomizes the central
triangular area, its shell is never exposed. Therefore,
VAYSSIERE (1898) was perfectly correct in not admitting

Page 52

Pleurobranchus scutatus into Pilsbry’s genus Gymnotoplax
(type species Pleurobranchus americanus Verrill, 1885) in
which the shell was supposedly exposed in the living an-
imal. In fact, as WILLAN (1978) has shown, that assump-
tion by Pilsbry was also incorrect, and no member of the
Pleurobranchidae exists in the living state with a shell
that is wholly or partially uncovered.

The only other pleurobranch known to autotomize its
mantle is the similar-looking Berthella kaniae Sphon, 1972,
that ranges from west Mexico to Panama in the tropical,
eastern Pacific Ocean. That species autotomizes irregular
chunks of its mantle border (SPHON, 1972) and apparently
has no “preformed shear zones” on the mantle; neither
does it have a deep cleft anteriorly.

Besides mantle autotomy, other unique features of Ber-
thella martensi: are the deep anterior cleft in the mantle,
the spotted mantle, the tail streak, the lines along the body,
the elongate and convex shell, the high radular formula,
the small teeth, the curved (not erect) outer lateral teeth,
the large rounded jaws, and branching off of the penial
gland far back along the distal vas deferens. The features
in which the central Pacific specimens match the original
Indian Ocean specimens of Berthella martensi are mantle
autotomy, the anterior cleft, the spotted mantle, the shell
and jaw shapes, the radular tooth shape, the large jaws,
and the wide-based mandibular elements. The only sig-
nificant difference between the two is the denticulate man-
dibular elements in the former, but as I have shown ear-
lier in this paper, these elements show great intraspecific
variation in pleurobranchs.

ACKNOWLEDGMENTS

I am particularly grateful to Mr. Scott Johnson for
sending me this collection of pleurobranchs together with
slides and information about the living animals. Ms. Lisa
Boucher kindly supplied the data on the spawn of Ber-
thella martenst. Mr. Johnson also sent additional material
from Hawaii. Comparative photographs were generously
made available by Mr. R. Burn, Mr. N. Coleman, and
Dr. P. Morse. Mr. Johnson, Mr. Burn, and Dr. E. Mar-
cus read and offered criticisms of the manuscript.

LITERATURE CITED

BabA, K. 1969. List of the Pleurobranchidae and Pleurobran-
chaeidae from Japan. Collecting and Breeding 31(7):190-
191.

BERGH, R. L. S. 1898. Die Pleurobranchiden.—Pleurobran-
chus. In: C. D. Semper, Reisen im Archipel der Philippinen
von Dr. C. Semper, Malakol. Unters. 7(3)[9-12]:117-158.

BerGH, R. L. S. 1900. Ergebnisse einer Reise nach dem Pa-
cific (Schauinsland 1896-1897). Die Opisthobranchier. Zool.
Jahrb. Abt. Allg. Zool. Physiol. Tiere 13(3):207-246, pls.
19-21.

BerGH, R. L. S. 1905. Die Pleurobranchiden.—Berthella. In:

C. D. Semper, Reisen im Archipel der Philippen von Dr.
C. Semper, Malakol. Unters. 9(2)[5—8]:57-115.
BertscH, H. 1975. Distributional and anatomical observa-

The: Veliger, Voll 274 Nom

tions of Berthella tupala (Opisthobranchia: Notaspidea).
Nautilus 89(4):124-126.

BERTSCH, H. & S. JOHNSON. 1981. Hawaiian nudibranchs.
Oriental Publishing Co.: Honolulu. 112 pp.

Burn, R. 1962. On the new pleurobranch subfamily Berthel-
linae (Mollusca: Gastropoda); a revision and new classifi-
cation of the species of New South Wales and Victoria.
Mem. Natl. Mus. Victoria 25:129-148.

EDMUNDs, M. & T. E. THoMpson. 1972. Opisthobranchiate
Mollusca from Tanzania. IV. Pleurobranchomorpha, Den-
dronotoidea and Arminoidea. Proc. Malacol. Soc. Lond.
40(3):219-233, 3 figs.

JOHNSON, S. 1982. Living seashells. Oriental Publishing Co.:
Honolulu. 116 pp., figs. 1-287.

Kay, E. A. 1979. Hawaiian marine shells. Reef and Shore
Fauna of Hawaii. Section 4: Mollusca. Bernice P. Bishop
Museum Special Publication 64(4):653 pp.

KuiTer, R. H. 1982. Fishing with film: nudibranchs. Scuba
Diver 1(5):31-39.

MacFarLanp, F.M. 1966. Studies of opisthobranchiate mol-
lusks of the Pacific Coast of North America. Calif. Acad.
Sci. Mem. 6:546 pp., pls. 1-72.

Marcus, Er. 1957. On Opisthobranchia from Brazil (2). J.
Linn. Soc. Lond. Zool. 43(262):390-486.

Marcus, Er. & J. B. BurcH. 1965. Marine euthyneuran
Gastropoda from Eniwetok Atoll, Western Pacific. Mala-
cologia 3(2):235-262, figs. 1-43.

Marcus, Er. & Ev. Marcus. 1970. Opisthobranch mollusks
from the southern tropical Pacific. Pacific Sci. 24(2):155-
179, 52 figs.

Marcus, Ev. 1977. On a pleurobranchid from the Mediter-
ranean. Veliger 19(4):418—421, 1 pl., 7 text figs.

Marcus, Ev. & Er. Marcus. 1958. Sea-hares and side-gilled
slugs from Brazil. Bol. Inst. Oceanogr. 6(1&2):3-33, pls.
1-8.

Marcus, Ev. & ER. Marcus. 1967. Tropical American op-
isthobranchs. Stud. Trop. Oceanogr. (Miami) 6(8):132 pp.,
155 figs.

MarTENs, E. von. 1880. Mollusken. Pp. 179-352. In: K. A.
Mobius (ed.), Beitrage zur Meeresfauna der Insel Mauri-
tius und der Seychellen, bearbeitet nach Sammlungen an-
gelegt auf einer Reise nach Mauritius von K. Moebius.
Guttmann Buchhandlung: Berlin. 352 pp., pls. 1-22.

O’DonoGHUE, C. H. 1929. Opisthobranchiate Mollusca col-
lected by the South African marine biological survey. Union
of South Africa Fish. Mar. Biol. Surv. Report 7(1):1-84,
pls. 1-8.

Pease, W. H. 1860. Descriptions of new species of Mollusca
from the Sandwich Islands. Proc. Zool. Soc. Lond. pt. 28:

18-37.
Pitssry, H. A. 1896. Manual of Conchology, Philadelphia
16:175-226.

PruvotT-Foi, A. 1934. Les opisthobranches de Quoy & Gai-
mard. Arch. Mus. Natl. Hist. Natur. (Paris) (6)11:13-89,
pl. 1, 30 figs.

RisBEc, J. 1928. Contribution a l’étude des nudibranches Néo-
Calédoniens. Faune Colon. Fr. 2:328 pp.

SPHON, G. 1972. Berthella kaniae, a new opisthobranch from
the eastern Pacific. Nautilus 86:53-55.

TuHompson, T. E. 1970. Eastern Australian Pleurobrancho-
morpha (Gastropoda, Opisthobranchia). J. Zool. (Lond.)
160:173-198.

VAYSSIERE, A. 1896. Description des coquilles de quelques
espéces nouvelles ou peu connues de pleurobranchidés. J.
Conchyliol. 44:113-137.

R. C. Willan, 1984

VAYSSIERE, A. 1898. Monographie de la famille des pleuro-
branchidés 1. Ann. Sci. Nat. Zool. Biol. Anim. 8(8):209-
402, pls. 13-28.

WILLAN, R. C. 1975. Identity and feeding of New Zealand
notaspidean opisthobranchs (Mollusca: Gastropoda). Mas-
ter’s Thesis. University of Auckland, New Zealand. 164 pp.

Rage 59

WILLAN, R. C. 1978. An evaluation of the notaspidean genera
Pleurobranchopsis Verrill and Gymnotoplax Pilsbry (Opis-
thobranchia: Pleurobranchinae). J. Conchol. 29:337-344.

WILLAN, R. C. 1983. New Zealand side-gilled sea slugs (Opis-
thobranchia: Notaspidea: Pleurobranchidae). Malacologia
23(2):221-270, 70 figs.

The Veliger 27(1):54-64 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

A New Species of Gastropteron from Florida

(Gastropoda: Opisthobranchia)

TERRENCE M. GOSLINER'

Division of Mollusks, National Museum of Natural History,
Smithsonian Institution, Washington, D.C. 20560

PATRICIA T. ARMES

410 N.W. 134th Way, Plantation,
Florida 33325

Abstract. ‘The morphology and biology of Gastropteron vespertilium Gosliner & Armes, spec. nov.,
from Tampa Bay, Florida, are described. A detailed comparison of G. vespertiliwm with G. rubrum
(Rafinesque, 1814) is provided, and consistent differences are noted.

INTRODUCTION

MEMBERS OF the Gastropteridae are widely distributed
throughout the world’s oceans. Only 3 of the 20 described
species have been recorded from the Atlantic Ocean (Gos-
liner, in press), with only a single species known to occur
in the western Atlantic (MARCUS, 1977).

In April, 1970, one of us (PTA) discovered a popula-
tion of an undescribed species of Gastropteron from inter-
tidal mudflats in Tampa Bay, Florida. Repeated obser-
vations have been made in successive years. This paper
describes aspects of the morphology and biology of this
species and discusses its systematic placement.

All figures, unless otherwise indicated were prepared
by one of us (TMG).

DESCRIPTION

Gastropteron vespertilium
Gosliner & Armes, spec. nov.

Type material: (1) Holotype: National Museum of Nat-
ural History, Washington, D.C., USNM 809992, 1 spec-
imen, swimming at surface, Bunces Pass, Tampa Bay,
Pinellas County, Florida, 1 February 1970, collected by
C. Powell. (2) Paratype: USNM 809993, one dissected
specimen with radular slide, Bunces Pass, Tampa Bay,

‘Permanent address: Department of Invertebrate Zoology,
California Academy of Sciences, San Francisco, CA 94118.

Florida, 1 February 1970, C. Powell. (3) Paratype:
USNM 809994, one dissected specimen, slides of radula,
penis and reproductive organs, Bunces Pass, Tampa Bay,
Florida, 1 February 1970, C. Powell.

Etymology: The specific epithet is derived from the Latin
vespertilio, meaning “‘bat.”’ When it is swimming by flap-
ping its parapodia, Gastropteron vespertilium resembles
a bat.

Distribution: Specimens have been found at only four
localities (Figure 1): Boca Ciega Inlet, Capri Island, the
north end of the Skyway Bridge, and Bunces Pass, all
within the vicinity of Tampa Bay, Florida.

External morphology: The living animals (Figures 2 to
5) are 3-5 mm in length and may reach 8 mm in width
when the parapodia are fully opened. The ground color
of the head, parapodia, and foot of the living animals
varies from charcoal-gray to purplish black. A line of bril-
liant yellow is generally present around the margins of
the parapodia and siphon. In some specimens the margin
is greenish or pale blue, with scattered blue-gray spots on
the parapodia. The flagellar appendage is charcoal-gray
basally and translucent white with occasional spots of gray
in its apical half. The head shield is triangular, slightly
emarginate antero-medially. Its posterior end is folded to
form a simple tubular siphon. The parapodia are thin and
fleshy. The foot (Figure 7) is broad and extends poste-
riorly behind the parapodia. Its posterior limit is trian-

T. M. Gosliner & P. T. Armes, 1984

Page 55

GQ\ Sf. Petersburg

° Tampa Bay
Gulf of Mexico i
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69 \ 3 km
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Figure 1

Collecting localities of Gastropteron vespertilium spec. nov.: 1,
Capri Island; 2, Boca Ciega Inlet; 3, north end of Sunshine
Skyway Bridge; 4, Bunces Pass.

gular and acute. Anteriorly, the foot is emarginate. A ped-
al gland empties by means of an elongate groove at the
posterior limit of the foot.

The gill (Figure 8) is situated on the right side of the
body and consists of 9 to 11 simply plicate leaflets. The
anus is situated immediately posterior to the gill. The
hermaphroditic gonopore is anterior to the gill and emp-
ties into the sperm groove, which transports endogenous
sperm to the male gonopore on the right side of the head.
The flagellum (Figures 2, 3, and 8) is situated on the
right side of the body and when fully extended may equal
half of the body length. Frequently the flagellum is par-
tially or completely retracted and may be entirely envel-
oped by the parapodia.

Shell: The weakly calcified, hyaline shell (Figures 6 and
23A) is 350 um in length and consists of approximately
two complete whorls.

Digestive system: The buccal mass is elongate and highly
muscular. The radula sac is situated at the posterior limit
of the buccal mass. In the anterior portion of the mass is
a thin labial cuticle which possesses several rows of minute
polygonal platelets (Figure 9). The radula (Figures 10 to
15) is well developed with a formula of 15-21 x 5-
6.1.0.1.5-6. The inner lateral teeth possess 17-25 minute

denticles. The outer lateral teeth lack denticles and grad-
ually decrease in size toward the outer margin of the rad-
ula.

Central nervous system: All of the ganglia are contained
within a circum-esophageal nerve ring (Figure 16). The
cerebral ganglia are separated by a short commissure. An-
teriorly, each cerebral ganglion gives rise to an enlarged
area and subsequently bifurcates into two nerves. The
pedal ganglia are joined by a commissure that is slightly
more elongate than the cerebral commissure. Adjacent to
the left cerebral ganglion is the left pleural ganglion, which
is also joined to the left pedal ganglion. The subintestinal
and visceral ganglia are adjacent to the left pleural gan-
glion. From the visceral ganglion the visceral loop passes
ventral to the esophagus and curves anteriorly to the su-
praintestinal ganglion on the right side of the nerve ring.
The supraintestinal ganglion is adjacent to the right pleu-
ral ganglion.

Reproductive system: The ovotestis is situated at the
posterior end of the visceral hump. From there a narrow
convoluted ampulla (Figure 17) is directed anteriorly. It
winds around the female gland mass and joins the duct of
the bursa copulatrix and the female gland mass at the
hermaphroditic gonopore. The ampulla lacks a distinct
receptaculum seminis in the two specimens examined. The
albumen and membrane glands are small and difficult to
discern, while the mucous gland comprises the bulk of the
female gland mass. The bursa copulatrix is spherical. The
penis (Figure 18) consists of an elongate prostate which
is thick and sharply curved. On the inner side of the pos-
terior end of the prostate is a spherical spermatic bulb
that joins the prostate by means of an elongate duct. The
penial papilla is short and rounded with a bilobed apex.

NATURAL HISTORY anp BEHAVIOR

Gastropteron vespertilium has been found only in the
vicinity of Tampa Bay. The three specimens that comprise
the type series were collected in early February, but the
numerous specimens collected at Boca Ciega Bay were all
found in April in several successive years. During April
the animals were abundant and occurred with egg masses.
By early May the population had entirely disappeared. It
is likely that the animals come into shallow water to breed.
This also is true for the nudibranch Dendronotus iris along
the California coast (TMG, personal observation), which
normally inhabits subtidal flats but is found commonly in
the intertidal during summer months when it is breeding.
It is interesting to note that both of these opisthobranchs
have remarkable natatory capabilities which facilitate their
transport.

Gastropteron vespertilium is found on intertidal sand
flats amid scattered plants of shoal grass, Diplanthera
wright Escher. The animals commonly crawl along the
surface of the substratum and occasionally burrow, but
like most known members of the Gastropteridae, they are

Page 56

The Veliger, Vol. 27, No. 1

i aa 5 %
.*

3

ws,

Explanation of Figures 2 to 5

Gastropteron vespertilium spec. nov. Figure 2. Lateral view (photograph by Rod Armes). Figure 3. Dorsal view
(photograph by Patricia Armes). Figure 4. Animal depositing egg mass (photograph by Patricia Armes). Figure

5. Animal swimming (photograph by Rod Armes).

also capable of swimming for prolonged periods (Figure
5). The animals swim by dorsal-ventral flapping of the
parapodia. The body is sometimes upright, but more fre-
quently inverted while swimming. Swimming is erratic,
characterized by rapid circling and darting. While swim-
ming, the animals often protrude the buccal region and a
white, viscous fluid is secreted. Little is known about feed-

ing in the Gastropteridae, but the remains of minute crus-
taceans were found in the stomach of several specimens of
G. vespertilium.

Extensive laboratory and field observations were made
of individuals undergoing copulation and egg deposition.
Copulation lasted 5-10 min in the pairs observed. The
egg mass (Figure 4) emerges from the hermaphroditic

T. M. Gosliner & P. T. Armes, 1984

Page 57

Figure 6

Shell of Gastropteron vespertilium spec. nov. Scale = 175 yum
(drawing by Sally D. Kaicher).

gonopore as a single strand of eggs enveloped by a coating
of mucus. There is generally a single yellowish egg per
capsule. Sixteen to twenty capsules are emitted at a rate
of one per second, followed by a three to four second pause
before another strand emerges. This procedure may con-
tinue for 20 min to an hour. The strands are formed into
a spherical mass, which is variable in size. Veliger larvae
hatched within three or four days of egg deposition.

When touched and seriously disturbed, specimens of
Gastropteron vespertilium exude a bright greenish-yellow
fluid that leaves a persistent yellow-orange stain that is
soluble in alcohol but not in water. While trying to relax
animals for fixation, it was determined that they could
withstand temperatures as low as 0°C for 15 min and still
revive. They died when the temperature was lowered to
—1°C for the same period.

DISCUSSION

The species of Gastropteridae are readily distinguish-
able on the basis of the external morphology and color-
ation of the living animal. Gastropteron vespertilium can
be differentiated from all other described members of the
family by its dark-gray or blue-black color. Gastropteron
vespertilium is placed in Gastropteron by virtue of its
radula, which contains five or six outer lateral teeth per
half row. Of the 14 previously described species of Gas-
tropteron only four, G. citrinum Carlson & Hoff, 1974, G.
fuscum Baba & Tokioka, 1965, G. ladrones Carlson &
Hoff, 1974, and G. rubrum (Rafinesque, 1814), possess a
single elongate flagellum on the right side of the body, as
in G. vespertilium. The first three species possess a ves-
tigial gill and only G. vespertilium and G. rubrum have
an elongate flagellum and a well-developed gill. Gastrop-

Explanation of Figures 7 and 8

Gastropteron vespertilium spec. nov. Scale = 1.0 mm. Figure 7.
Ventral view: m, mouth; pg, pedal gland. Figure 8. Right lateral
view: a, anus; f, flagellum; g, gill.

Figure 9

Jaw of Gastropteron vespertilium spec. nov. Scale = 0.25 mm.

1GKY WO:1GNM = =65:OB221 P0088

The Veliger, Vol. 27, No. 1

16K WO: 26MM §: 60221

Explanation of Figures 10 to 13

Gastropteron vespertiltum spec. nov. Scanning electron micrographs of radular teeth. Figure 10. Entire radular
width. Figures 11 to 13. Inner lateral teeth from various angles.

teron rubrum is also the only other species of the family
known from the western Atlantic (MARCUS, 1977). For
these reasons a detailed comparison of G. rubrum and G.
vespertilium is provided. In addition to records of G.

rubrum from the literature (VAYSSIERE, 1880, 1885;
BERGH, 1893; GUIART, 1901; MARcus & Marcus, 1966;
SALVINI-PLAWEN & ABBOTT, 1974), specimens from Pa-
lermo, Italy (four specimens, Museum National d’His-

T. M. Gosliner & P. T. Armes, 1984 Page 59

16KV WO: 16MM §$:0221 P:gga48

Explanation of Figures 14 and 15

Gastropteron vespertilium spec. nov. Scanning electron micrographs of radular teeth. Figure 14. Half rows of
teeth. Figure 15. Outer lateral teeth.

Page 60 The Veliger,, Voly Zip

Table 1

Morphological comparison of Gastropteron rubrum and G. vespertilium.

#
denticles
# of gill on inner Spermatic
Reference, locality lamellae Radular formula lateral Prostate bulb

Gastropteron VAYSSIERE, 1880, 1885 = 40X5.1.0.1.5. 26 elongate absent
rubrum Mediterranean

Gastropteron BERGH, 1893 25-30 20-23X5.10.1.5. 4-18 elongate absent
rubrum Naples

Gastropteron Marcus, 1960; present study 11 17X5-6.1.0.1.5-6. 15-18 elongate absent
rubrum Bear Cut, Key Biscayne

Gastropteron present study 10 20X5-6.1.0.1.5-6. 16-28 elongate absent
rubrum Grand Cayman Is.

Gastropteron Marcus & Marcus, 1966; present study 23 23X5.1.0.1.5. 18-26 elongate absent
rubrum manx Gulf of Guinea

Gastropteron present study 9-10 15-27X5.6.1.0.5-6. 17-25' short present
vespertilium Tampa Bay

Explanation of Figures 16 to 18

Gastropteron vespertilium spec. nov. Scale = 1.0 mm. Figure 16. Central nervous system: c, cerebral ganglion; pe,

T. M. Gosliner & P. T. Armes, 1984 Page 61

1GKVY WO:1@MM $:@0221 P:a0061

J

t.

Explanation of Figures 19 and 20

Figures 19 and 20. Gastropteron rubrum (Rafinesque, 1814). Radular teeth of specimen from Grand Cayman
Island. CASIZ 034121.

pedal ganglion; pl, pleural ganglion; sb, subintestinal ganglion; sp, supraintestinal ganglion; v, visceral ganglion.
Figure 17. Reproductive system: am, ampulla; bc, bursa copulatrix; fg, female gland mass; ga, genital aperture.
Figure 18. Penis: p, penis; pr, prostate; s, spermatic bulb.

Page 62

The Veliger, Vol. 27, No. 1

16KV WO:16MM §:60221 P: 90069

& 1@KY WO: 16MM

a,
a

:

Explanation of Figures 21 and 22

Figures 21 and 22. Gastropteron rubrum (Rafinesque, 1814). Radular teeth of specimen from Bear Cut, Key

Biscayne. USNM 836667.

toire Naturelle, Paris), Grand Cayman Island (one spec-
imen, California Academy of Sciences, San Francisco,
CASIZ 034121, Grand Cayman Island, Seven Mile Beach,
Caribbean Club, 150 m off shore, just below surface, col-

lected by James E. Sutton, 30 June 1974) and Miami,
Florida (one specimen, National Museum of Natural
History, USNM 836667, Bear Cut, Biscayne Bay, col-
lected by Sandra Maxwell, 21 May 1966) were examined.

T. M. Gosliner & P. T. Armes, 1984

Figure 23

Shells. A. Gastropteron vespertilium spec. nov. B. Gastropteron
rubrum (Rafinesque, 1814), after Vayssiére, 1885. Not to scale
(drawing by Sally D. Kaicher).

The holotype of G. rubrum manx Marcus & Marcus,
1966 (National Museum of Natural History, Washing-
ton, USNM 576262, Gulf of Guinea, R.V. Pillsbury sta-
tion 241) was also reexamined.

The present material of Gastropteron rubrum is well
within the range of variation previously described for the
species, with a few minor exceptions (Table 1). In one
specimen there were as many as 28 denticles on the inner
lateral tooth and in another specimen there were only 17
rows of radular teeth. The two western Atlantic specimens
have 10 or 11 gill filaments which is fewer than previously
reported.

Gastropteron vespertilium is exceedingly similar to G.
rubrum in much of its external and internal morphology.

Page 63

Gastropteron vespertilium is reproductive at 3 mm in
length and reaches a maximum length of 5 mm. The two
small individuals of G. rubrum from the western Atlantic
were 2.5 and 3 mm in length, but were not fully mature.
The penis was well developed but the female gland mass
had not yet undergone differentiation. Gastropteron ru-
brum is known to reach a length of 24 mm (VAYSSIERE,
1880). The jaws and radulae of G. vespertilium and G.
rubrum provide little basis for the separation of the species
(Figures 10 to 15 and 19 to 22). There is considerable
overlap in radular formulae and in the number of denti-
cles on the inner lateral teeth. The number of gill fila-
ments is similar in G. vespertilium and in specimens of
G. rubrum of comparable size. The central nervous system
is virtually identical in both species (VAYSSIERE, 1880;
BERGH, 1893; present study).

The major differences between Gastropteron vespertili-
um and G. rubrum, other than the obvious and consistent
differences in coloration, are in the shape of the shell and
the reproductive morphology. In G. vespertilium the in-
ner margin of the shell (Figure 23) is entire, whereas in
G. rubrum there is a deep sinus.

The reproductive system has been completely described
in only three species of Gastropteron (GUIART, 1901;
MAcFARLAND, 1966; GOSLINER, in press). In G. rubrum
a semi-serial receptaculum seminis is absent but a serial
receptaculum, which appears as a swelling of the her-
maphroditic duct (Figure 24), is present in all described
material (BERGH, 1893; GUIART, 1901; present study). In
the two specimens of G. vespertilium that we examined,
the hermaphroditic duct lacks either a serial or semi-serial

Explanation of Figures 24 and 25

Gastropteron rubrum (Rafinesque, 1814). Figure 24. Reproductive system: am, ampulla; bc, bursa copulatrix; fg,
female gland mass; ga, genital aperture; rs, receptaculum seminis. Scale = 2.0 mm. Figure 25. Penis: p, penis; pr,

prostate. Scale = 3.0 mm.

Page 64

receptaculum and is of a uniform diameter throughout its
length.

The structure of the penis also differs significantly be-
tween the two species (Figures 17 and 25). In Gastropte-
ron rubrum (BERGH, 1893; GuIART, 1901; Marcus &
Marcus, 1966) there is a narrow elongate prostate that
consists of numerous convolutions. The penial papilla is
elongate and conical. In G. vespertilium the prostate is
thick and curved, but not convoluted. A distinct spermatic
bulb is present. The penial papilla is exceedingly short
and bifid at its apex.

Despite the similarities between Gastropteron vesper-
tilium and G. rubrum in many aspects of their external
and internal anatomy, the striking differences in color-
ation and the morphology of the shell, hermaphroditic
duct, and penis ensures that they are distinct species. Al-
though both species are found in the western Atlantic of
Florida, they may not be sympatric. Gastropteron rubrum
is known from the Atlantic coast of Florida to Brazil, but
no confirmed reports exist from the Gulf of Mexico. Gas-
tropteron vespertilium has only been collected in Tampa
Bay, on the Gulf coast of Florida, but is likely to be more
widespread.

ACKNOWLEDGMENTS

Numerous individuals and institutions provided sub-
stantial assistance at various stages in the completion of
this work, including Sally D. Kaicher, Harold Humm,
Susan and John Gallagher, Gale Sphon, Eveline Marcus,
William Lyons, Johanna Reinhart, George Reid, the late
Francis and Emily Smith, George W. Torrance, R. Tuck-
er Abbott, Joseph Rosewater, Rod Armes, Robert Rob-
ertson, Nelson Cooley, Edward Petuch, Alan Bebbington,
Vera Fretter, Victor Krantz, and the Museum National
d’Histoire Naturelle, and the libraries of University of
South Florida, Eckerd College, and the Florida State Board
of Natural Resources, St. Petersburg Marine Research
Laboratory. To them, we extend our sincere appreciation.

Whe Veliger, Vol Zi Nom

LITERATURE CITED

BasBa, K. & T. ToxioKa. 1965. Two more new species of
Gastropteron from Japan, with further notes on G. flavum
T. & B. (Gastropoda: Opisthobranchia). Publ. Seto Mar.
Biol. Lab. 12(5):363-378 (10 March 1965).

BERGH, R. L. S. 1893. Die Gattung Gastropteron. Zool. Jahrb.,
Abt. Anatomie u. Ontongenie 7(2):281-308.

CARLSON, C. & P. J. Horr. 1974. The Gastropteridae of Guam
with descriptions of four new species (Opisthobranchia: Ce-
phalaspidea). Publ. Seto Mar. Biol. Lab. 21(2):141-151 (31
March 1974).

GOSsLINER, T. M. In press. Two new species of Gastropteron
(Gastropoda: Opisthobranchia) from southern Africa. Publ.
Seto Mar. Biol. Lab. 33.

GurarT, J. 1901. Contribution a l’étude des gastéropodes opis-
thobranches et en particulier des Céphalaspidés. Mem. Soc.
Zool. de France 14:5-219.

MacFarLanbD, F. M. 1966. Studies of opisthobranchiate mol-
lusks of the Pacific coast of North America. Mem. Calif.
Acad. Sci. 6:1-546.

Marcus, Ev. 1977. An annotated checklist of the Atlantic
warm water opisthobranchs. J. Moll. Stud., supp. 4:1-22
(November 1977).

Marcus, Ev. & ER. Marcus. 1960. Opisthobranchs from
American Atlantic warm waters. Bull. Mar. Sci. Gulf &
Carib. 10(2):129-203.

Marcus, Ev. & ER. Marcus. 1966. The opisthobranchs from
tropical West Africa. Stud. Trop. Oceanogr. Miami 4(1)(9):
152-208.

RAFINESQUE, C. S. 1814. Quadro dei generi di Moll. Ptero-
podi. Jn: Specchio delle Sci. 1, p. 11.

SALVINI-PLAWEN, L. v. & R. T. ABBotr. 1974. The gastro-
pods. Jn: Grimek’s Animal Life Encyclopedia. Volume 3.
Mollusks and Echinoderms. Van Nostrand Reinhold: New
York. 541 pp.

VAYSSIERE, A. 1880. Recherches anatomiques sur les mol-
lusques de la famille des bullides. Ann. Sci. Nat. Zool., ser.
6, 9:1-123.

VAYSSIERE, A. 1885. Recherches zoologiques et anatomiques
sur les mollusques opisthobranches du Golfe de Marseille.
1. Tectibranches. Ann. Mus. Hist. Nat. Marseille, Zool.
2(3):1-181.

The Veliger 27(1):65-71 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

Notes on the Tergipedid Nudibranchs of the

Northeastern Pacific, with a

Description of a New Species

DAVID W. BEHRENS

Pacific Gas & Electric Co., Biological Research Laboratory,
P.O. Box 117, Avila Beach, California 93424

Abstract. In the northeastern Pacific the family Tergipedidae is represented by 14 described species
and at least 1 known undescribed species. The nomenclatural status of the family is reviewed and a
new species, Catriona rickettsi Behrens, from California is described.

THE SYSTEMATICS of the family Tergipedidae Thiele, 1931,
have experienced considerable controversy and nomencla-
tural confusion. Its taxonomic evolution has been reviewed
by BuRN (1973), MILLER (1977), and WILLIAMS &
GOSLINER (1979). Modifications have followed with
BROWN (1980), GOSLINER (1981), and GOSLINER & GRIF-
FITHS (1981). In the northeastern Pacific, species accounts
are reported by MACFARLAND (1966), ROLLER (1969),
LONG (1969), GOSLINER & MILLEN (1984), and JAECKLE
(1984).

The generic status of Catriona Winckworth, 1941, Cu-
thona Alder & Hancock, 1855, and Trinchesia Ihering,
1879, has changed several times. MILLER (1977) found
no clear separation between the genera. WILLIAMS &
GOSLINER (1979) reestablished Catriona as a valid genus
based upon the presence of bristles on the masticatory
border of the jaw and the possession of more than 50
radular teeth. They also reported the family name Ter-
gipedidae inappropriate and recommended Cuthonidae.
BROWN (1980), while reviewing the British species, re-
vised Williams & Gosliner on both these matters, follow-
ing the nomenclature of MILLER (1977). GOSLINER &
GRIFFITHS (1981), while not discussing Brown’s revision,
reemphasized the features separating Catriona from Cu-
thona, and stressed the importance of preradular teeth in
Catriona.

Notes on the Tergipedidae of the
Northeastern Pacific

Table 1 summarizes the tergipedid species known from
the northeastern Pacific, and for which accurate collection
data and/or voucher material is available. The list gives

the known geographical distribution of each species and
the authors reporting those range limits.

THOMPSON & BROWN (1976) report “fone doubtful rec-
ord of” Cuthona nana (Alder & Hancock, 1845-55) from
the Pacific coast of North America. No confirmable col-
lection of C. nana is known from this coast. HURST (1967)
reported Catriona gymnota (Couthuoy, 1838) (=Catriona
aurantia Alder & Hancock, 1842) (fide WILLIAMS &
GOSLINER, 1979; BROwN, 1980) from the vicinity of Fri-
day Harbor Marine Laboratories, San Juan Island,
Washington. ROBILLIARD (1971) documented collections
of Catriona columbiana from this area, but not C. gymnota.
Whereas the type locality of C. columbiana is Gabriola
Pass, Vancouver Island region, British Columbia, and C.
gymnota has not been reported since Hurst (1967), it
should probably be considered a misidentification.

BEHRENS (1980a:104) included four additional uniden-
tified tergipedid nudibranchs. One, the La Jolla aeolid
(species No. 158) remains undescribed. Tergipes sp.
(species No. 160) has subsequently been described as Cu-
thona phoenix Gosliner, 1981.

The Lake Merritt aeolid (BEHRENS, 1980a:104, species
No. 154) has also been listed by MCDONALD & NYBAKKEN
(1980:64) as Cuthona species A, and by MCDONALD (1983:
169) as Trinchesia sp., both from San Francisco Bay, Cal-
ifornia. This species was collected from Lake Merritt in
1967 by Dr. James T. Carlton. Subsequent to the pub-
lication of the color photograph in BEHRENS (1980a), Dr.
Terrence Gosliner and Mr. Robert Burn brought to my
attention the striking similarity between this species and
Cuthona perca (Er. Marcus, 1958). Cuthona perca has been
reported from an extremely wide geographical area, in-
cluding Brazil (ER. Marcus, 1958), Jamaica (EDMUNDs,
1964), Florida (Ev. Marcus, 1972), Barbados (MARCUS

Page 66

Table 1

List of northeastern Pacific Tergipedidae.

Cuthona Alder & Hancock, 1855

C. abronia (MacFarland, 1966): Mukkaw Bay, Washington
(ROBILLIARD, 1971)-Santa Catalina Island, California
(JAECKLE, 1983)

C. albocrusta (MacFarland, 1966): San Juan Island, Wash-
ington (Hurst, 1967)-Palos Verdes, California (Mc-
DONALD, 1983)

C. cocochroma Williams & Gosliner, 1979: Trinidad Bay,
Humboldt Co. (JAECKLE, 1984)—-Duxbury Reef, Marin Co.,
California (WILLIAMS & GOSLINER, 1979)

C. concinna (Alder & Hancock, 1843): Brandon Island near
Nanaimo, Vancouver Island, British Columbia (O’DoONo-
GHUE, 1922), Circum-polar

C. divae (Marcus, 1961): San Juan Islands, Washington
(ROBILLIARD, 1971)-—Point Loma, California (HAMANN,
1981)

C. flavovulta (MacFarland, 1966): Palmer’s Point, Humboldt
Co. (JAECKLE, 1984)-Shell Beach, San Luis Obispo Co.,
California (ROLLER & LONG, 1969)

C. fulgens (MacFarland, 1966): Duxbury Reef, Marin Co.
(GOSLINER & WILLIAMS, 1970)-Shell Beach, San Luis
Obispo Co., California (LONG, 1969)

C. lagunae (O’Donoghue, 1926): Palmer’s Point, Humboldt
Co., California (JAECKLE, 1984)—Punta Cabras, Mexico
(HAMANN, 1981)

C. perca (Marcus, 1958): San Francisco Bay and Lake Mer-
ritt, Oakland, California (present study), Brazil (MARCUS,
1958), Jamaica (EDMUNDS, 1964), Florida (Ev. Marcus,
1972), Barbados (MARCUS & HUGHES, 1974), New Zealand
(MILLER, 1977), Hawaii (GOSLINER, 1980)

C. phoenix Gosliner, 1981: Morro Bay (BEHRENS, 1980a),
Mission Bay (GOSLINER, 1981) and La Jolla, California
(BEHRENS, 1980a)

C. pustulata (Alder & Hancock, 1845): Saltspring Island, Gal-
iano Island, Strait of Georgia, British Columbia, Canada,
and the northeastern Atlantic (GOSLINER & MILLEN, 1984)

C. virens (MacFarland, 1966): Duxbury Reef, Marin Co.
(McDoNALD & NYBAKKEN, 1980)-Santa Catalina Island,
California (JAECKLE, 1983)

C. species 1: La Jolla, California (J. Lance, personal com-
munication)

Catriona Winckworth, 1941

C. columbiana (O’ Donoghue, 1922): Pearse Island, British Co-
lumbia (LAMBERT, 1976)-San Diego, California (LANCE,
1966), Japan (BABA & HAMATANI, 1963), South Africa
(GOSLINER & GRIFFITHS, 1981)

C. rickettsi Behrens, spec. nov.: San Francisco Bay, California
(present study)

Tenellia Costa, 1877

T. adspersa (Nordmann, 1845): San Francisco Bay (STEIN-
BERG, 1963)-Morro Bay, California (MCDONALD &
NYBAKKEN, 1980), Europe, New England

& HuGHEs, 1974), and New Zealand (MILLER, 1977) as
C. reflexa, and Hawaii (GOSLINER, 1980).

The San Francisco Bay specimens match identically
descriptions given in MILLER (1977) and GOSLINER (1980)
for Cuthona perca. The radular length of 28 teeth fits well

The Veliger,, Vol? 2p Nom

within the range of 16 to 35 reported in the above refer-
ences. GOSLINER (1980) reports 11 denticles per tooth.
The San Francisco Bay specimens bear 5-10 denticles per
tooth. The radular drawing presented in MCDONALD
(1983) matches closely that shown in GOSLINER (1980)
for the Hawaiian specimens. The coloration of the spec-
imens also matches closely that previously reported. The
body is translucent grayish-white with white specks. The
cerata bear numerous opaque white specks and a similarly
colored subapical white band. The ceratal cores are olive-
green.

The two localities where this species has been collected
in California are a tidal lagoon, which due to its distance
from the shore of San Francisco Bay is called a “lake,”
and the Palo Alto Yacht Harbor, South San Francisco
Bay (BEHRENS, 1980b; MCDONALD & NYBAKKEN, 1980;
McDOona_p, 1983). Both water bodies exhibit marked
differences from California coastal waters; during the
summer months they are quite warm and highly saline.
The feasibility of the introduction of species such as Cu-
thona perca is discussed by CARLTON (1975, 1978, 1979)
and MILLER (1969). At each of these localities, this species
was feeding on the same sea anemone species, the intro-
duced Asian anemone, Halipanella luciae (Verrill, 1898)
(McDONALD, 1983; present study).

The fourth species listed in BEHRENS (1980a:104),
Trinchesia sp. (species No. 161), is described in this paper.
It was originally reported by BEHRENS & TUEL (1977),
after being collected in San Francisco Bay in 1974. This
Catriona is one of the most abundant aeolidacean species
occurring year-round in south San Francisco Bay. Spec-
imens have also been collected in La Jolla, California by
Mr. James R. Lance.

Family TERGIPEDIDAE Thiele, 1931
Catriona Winckworth, 1941
Catriona rickettsi Behrens, spec. nov.
(Figures 1 to 7)

References and synonymy:

Trinchesia sp.: BEHRENS & TUEL, 1977:35. CARLTON, 1979:
432. BEHRENS, 1980a:37. BEHRENS, 1980b:104.

Type material: (1) Holotype: One specimen approxi-
mately 13 mm long (preserved) collected from boat floats
at Pete’s Harbor, Port of Redwood City, San Francisco
Bay, California (Lat. 37°30'02”N; Long. 122°13’23”W)
on December 24, 1981, by David W. Behrens. This spec-
imen is deposited in the collection of the California Acad-
emy of Sciences, Departments of Invertebrate Zoology and
Geology (CAS), San Francisco, California (CAS Cata-
logue No. 029323). (2) Paratypes: A series of six speci-
mens 8-15 mm long (preserved) collected concurrently
with the holotype is also deposited in the CAS collection,
Catalogue No. 029324. (3) A series of six specimens 6-9
mm long (preserved) collected at the type locality on April

D. W. Behrens, 1984

Page 67

Figure 1

Catriona rickettst spec. nov. Two specimens, each 18 mm in length. Pete’s Harbor, Port of Redwood City, San
Francisco Bay, California. Drawn from color transparencies.

18, 1981, is deposited in the type collection of Los Angeles
County Museum of Natural History (LACM). Color
transparencies of living Catriona rickettsi are on file at
CAS (Nos. 3749, 3750 and 3751) and LACM.

Other material examined:

(1) 18 specimens, Pete’s Harbor, Port of Redwood City,
San Mateo County, California; /eg. David W. Behr-
ens, 24 September 1974.

(2) 20 specimens, Pete’s Harbor, Port of Redwood City,
San Mateo County, California; Jeg. David W. Behr-
ens, 23 November 1978.

(3)

(4)

(5)

(6)

12 specimens, Pete’s Harbor, Port of Redwood City,
San Mateo County, California; /eg. David W. Behr-
ens, 12 August 1979.

25 specimens, Pete’s Harbor, Port of Redwood City,
San Mateo County, California; Jeg. David W. Behr-
ens, 27 November 1980.

15 specimens, Pete’s Harbor, Port of Redwood City,
San Mateo County, California; Jeg. David W. Behr-
ens, 18 April 1981.

20 specimens, Pete’s Harbor, Port of Redwood City,
San Mateo County, California; /eg. David W. Behr-
ens, 26 November 1981.

Page 68

\

Ventral view of Catriona rickettsi spec. nov. 16 mm length. Pete’s
Harbor, Port of Redwood City, San Francisco Bay, California.
Drawn from color transparency.

Figure 2

(7) 18 specimens, Pete’s Harbor, Port of Redwood City,
San Mateo County, California; Jeg. David W. Behr-
ens, 24 December 1981.

Description: The living animals measured up to 20 mm
in length. Body is long, slender, tapering posteriorly. Tail
is about % the body length (Figure 1). The anterior por-
tion of the foot flares slightly and is rounded (Figure 2).
The foot is roughly 4, as wide as long. The oral tentacles
are long and slender and about % the length of the rhin-
ophores (Figure 1). The rhinophores are long, about 4-
¥, the length of the body, smooth to very slightly verrucose,
and tapering. The cerata are arranged in 8-10 rows, the
longest of which bears up to six cerata. There are up to
four rows of cerata in the prepericardial group. Postper-
icardial rows alternate. A typical ceratal arrangement was
2.3.4 (prepericardial) and 5.6.3.1.1 (postpericardial). A
single ceras (Figure 3), when fully extended, is approxi-
mately %-% the length of the body. Ceratal shape varies
greatly from fusiform to a more club shape. The anus lies
immediately in front of the dorsal-most ceras of the first
postpericardial row. The genital apertures lie on the right
side of the body, ventral to the first and second anterior
rows of cerata.

The body is translucent, allowing many of the organs
to be seen. In some larger specimens, the region between
the rhinophores and the pericardium is yellow to orange.
There is opaque white pigment on the distal % of the
rhinophores and cephalic tentacles and at the apex of the
cerata. On the tentacles, this pigmentation is restricted to

Figure 3

Ceras from Catriona rickettsi spec. nov.

The Veliger, Vol: 277 Noma

Figure 4

Radular teeth of Catriona rickettsi spec. nov.

the dorsal surface. An occasional white speck may occur
on the surface of the cerata or on the notum. A band of
orange is found below the white apices of the rhinophores
and cephalic tentacles. This band may be nearly indiscer-
nible on the tentacles in some individuals. The color of
the ceratal core varies greatly, from yellow through or-
ange, pink, red-brown, burgundy, or brownish-green. In
some specimens the color may gradate from greenish,
proximally, to reddish-brown below the white cap. A color

Figure 5

Jaw of Catriona rickettsi spec. nov. a, lateral view of jaw. b,
masticatory border.

D. W. Behrens, 1984

Page 69

Figure 6

Penis of Catriona rickettsi spec. nov.

photograph of a specimen with orange cerata can be found
in BEHRENS (1980a:105).

The long, tapering uniseriate radula is composed of up
to 75 teeth, including three preradular teeth. Each tooth
is a low horseshoe-shaped arch, with a deep articulatory
socket on either side (Figure 4). The central cusp forms
a long ridge that extends slightly below the blade of the
tooth. There are 3-5 large denticles to each side of the
cusp, three of which project further than the central cusp
itself. One or two small denticles may be found between
the larger ones (Figure 4). The consistency of these small-
er denticles was confirmed using scanning electron mi-
croscopy (SEM). The jaws (Figure 5a) are lightly tinted
gold, thin and oval. The masticatory process has a series
of coarse denticles, with faintly discernible bristles (Figure
5b).

The reproductive system was typically tergipedid. The
hermaphrodite glands are large, spherical to oval, tightly
covered with elongated, inflated peripheral female acini.
They extend posteriorly to the last division of the digestive
gland and discharge into a median hermaphrodite duct.
The ampulla is very long and convoluted. The vas def-
erens is very short. The penial gland is long, recurved and
slightly inflated at its distal end. The penis is short, con-
ical, and blunt (Figure 6). Upon dissection and clearing
with 0.5 N quaternary ammonium hydroxide, it was found
to be unarmed.

In South San Francisco Bay, Catriona rickettsi has been
collected from a variety of fouling communities. Egg masses
are present year-round, indicating the presence of this
small, highly cryptic tergipedid. The egg mass (Figure 7)
is typical of Type D (Hurst, 1967), being an irregularly
twisted, clear gelatinous string housing a spiral or folded
string of white-cream eggs. A large egg string contains
12-30 eggs in cross-section (Figure 7b), with one egg per
capsule. The mass is attached to the substratum, usually
the stalk of a hydroid, by a very thin capsule-free jelly
sheet. An average tangled mass measures about 2 by 6
mm.

The preferred substratum of this species seems to be
Tubularia crocea (Agassiz, 1862), the hydranth of which
the aeolid closely resembles, both in color and form. Other
cnidarian species common in this locality are Obelia sp.
and Halipanella luciae, the latter of which also closely
resembles the ceratal morphology of Catriona rickettst.

Figure 7

Egg mass of Catriona rickettsi spec. nov. a, whole egg mass (6
mm long) attached to hydroid stalk. b, view of single strand of
egg string within a mass. Drawn from color transparency.

Discussion: Eight species are assigned to the genus Catri-
ona based upon a long, tapering radula of greater than 50
teeth and the presence of a preradular tooth (GOSLINER
& GRIFFITHS, 1981). Until this study, only Miller’s C.
alpha from New Zealand lacked a penial stylet. All species
except C. oba Marcus, 1970, bear bristles on the masti-
catory edge of the jaw. Limited by these characteristics,
assignment of C. rickettsi to this genus seems most ap-
propriate.

Catriona maua Marcus & Marcus, 1960, and C. oba
differ from C. rickettst in that they bear a red line on the
rhinophores. Catriona gymnota (Couthouy, 1938), C. tema
Edmunds, 1968, and C. casha Gosliner & Griffiths, 1981,
differ from C. rickettsi in having a subapical white band
on the cerata. ‘These species also have geographic distri-
butions far from that of C. rickettst.

In the northeastern Pacific, Catriona rickettsi most
closely resembles Catriona columbiana (O’ Donoghue, 1922).
Differences in surface pigmentation (a highly consistent
character in this genus), radular dentition, penial arma-
ture, structure of the masticatory border of the jaw, and
the egg mass set the two sympatric species apart.

WILLIAMS & GOSLINER (1979) synonymized Catriona
alpha Baba & Hamatani, 1963, with C. columbiana. The
primary similarity was that of coloration. The particular
features of coloration have been stressed by several au-
thors. BABA & HAMATANI (1963) report in their descrip-
tion of the species that the holotype had ‘‘opaque white
dots on the head region . . . and on nearly the whole length
of the branchial papillae on their surface.” They report
also that the paratype had branchial papillae with an
outer longitudinal, opaque-white line. MACFARLAND

Page 70

(1966) in describing C. columbiana (as C. spadix) reports
that the cerata bear a broad frosted-white band extending
from base to tip. MCDONALD (1983) describes the color-
ation of the species similarly. GOSLINER & GRIFFITHS
(1981) report C. columbiana from South Africa. In their
specimens, opaque white pigmentation covered the surface
of the cerata, spreading to the notal surface. They report
that the coloration agrees with that of the holotype of C.
alpha, stating that, within the geographical range of C.
columbiana, the external opaque white occurs over the
whole surface or is restricted to a white longitudinal line
or subapical band on the cerata. LANCE (1966), while
reporting its collection in southern California, states that
the color pattern of this species is distinct, enabling it to
be readily distinguished from other aeolid nudibranchs.
He reports that the antero-dorsal surface of all cerata,
except the smallest, is covered with a highly contrasting,
intense opaque-white pigment. The pigment was also
present on the dorsal surface of the head as a trianglar
patch (LANCE, 1966; also see BEHRENS, 1980a:84).
GOSLINER & MILLEN (1984) distinguish C. columbiana
from all other sympatric species in Canadian waters by
the white opaque ceratal line. Catriona rickettsi has none
of the above-mentioned color patterns.

GOSLINER & GRIFFITHS (1981; fig. 15) present a com-
parison of the radular teeth of Catriona. Although striking
differences occur between the four examples of Catriona
columbiana presented (after O’ DONOGHUE, 1922; BABA &
HAMATANI, 1963; MACFARLAND, 1966; and GOSLINER &
GRIFFITHS, 1981), the denticulation and morphology de-
scribed here for C. rickettsi (3-5 large denticles between
which lie 0-2 smaller denticles) remain substantially dif-
ferent enough for the purpose of species separation.

In the original description, O7 DONOGHUE (1922) did
not illustrate the penis or stylet of Catriona columbiana. In
C. rickettsi the penis is short and blunt, not elongate and
tapering as shown for any of the examples of C. colum-
biana given in GOSLINER & GRIFFITHS (1981). Addition-
ally, the presence of a penial stylet was not described by
BaBA & HAMATANI (1963) for C. columbiana (as C. al-
pha). ROLLER (1969) confirmed the presence of a penial
stylet in the Japanese C. columbiana. Catriona rickettsi
has no such penial armature.

GOSLINER & GRIFFITHS (1981) describe the bristles on
the denticles of the masticatory border of the jaw as large
and clearly defined; ROLLER’s (1969) description is simi-
lar. In Catriona rickettsi, the bristles are faintly discern-
ible. This interspecific difference was confirmed by Dr.
Kikutar6 Baba (personal communication).

The egg mass of Catriona columbiana is a bag-like sac
(Sandra Millen, personal communication) and not a spiral
or folded string as is described here for C. rickettsi and
is more typical of tergipedid nudibranchs (Hurst, 1967).

MILLER (1977) identified specimens as Catriona alpha
from New Zealand. His specimens reportedly differ from
the Japanese specimens in a manner similar to the species
from south San Francisco Bay described here. GOSLINER

The Veliger,, Vol) 27 Noml

& GRIFFITHS (1981), while comparing New Zealand ma-
terial with that from South Africa and California, amplify
the described differences between Miller’s species and C.
columbiana. The reported ceratal variability, lack of char-
acteristic white markings, and lack of penial stylet closely
match characters described here for Catriona rickettst.
Miller’s specimens, however, lack bristles on the masti-
catory border of the jaw. Further examination of the New
Zealand species is required to confirm its status.

The trivial name rickettsi is given in honor of Edward
F. Ricketts (1897-1948) for his outstanding contributions
in the field of philosophy and to our understanding of
intertidal ecology. HEDGPETH (1978a, b) presents a chro-
nology of the life of Ricketts, highlighting the man and
his contributions.

ACKNOWLEDGMENTS

I would like to express thanks to my children, Jennifer
and Michael Behrens, for their assistance in the collection
of specimens for this description. Thanks also are due to
Sandra Millen and the referees for their critical review
of, and recommendations on, the manuscript. I also thank
David Zoutendyk for providing the scanning electron mi-
croscopy of the radula.

LITERATURE CITED

Baba, K. & I. HAMATANI. 1963. A cuthonid, Cuthona alpha n.
sp., with a radula of Catriona type (Nudibranchia-Eolida-
cea). Publ. Seto Mar. Biol. Lab. 11(2):169-174.

BEHRENS, D. W. 1980a. Pacific coast nudibranchs: a guide to
the opisthobranchs of the northeastern Pacific. Sea Chal-
lengers Inc.: Los Osos, Calif. 112 pp.

BEHRENS, D. W. 1980b. A review of the literature of the opis-
thobranchs of San Francisco Bay. Opisthobranch Newslet-
ter 12(4-12):34-37.

BEHRENS, D. W. & M. TueEL. 1977. Notes on the opistho-
branch fauna of South San Francisco Bay. Veliger 20(1):
33-36.

Brown, G. H. 1980. The British species of the aeolidacean
family Tergipedidae (Gastropoda: Opisthobranchia) with a
discussion of the genera. Zool. J. Linn. Soc. 69(7):225-255.

Burn, R. 1973. Opisthobranch molluscs from the Australian
Sub-Antarctic territories of Macquarie and Heard Islands.
Proc. Roy. Soc. Vict. 86(1):39-46.

CarLTon, J. T. 1975. Introduced intertidal invertebrates. Pp.
17-25. In: R. I. Smith & J. T. Carlton (eds.), Light’s man-
ual: Intertidal invertebrates of the Central California Coast.
3rd edition. Univ. of California Press: Berkeley, Calif.

CaRLTON, J. T. 1978. History, biogeography and ecology of
introduced marine and estuarine invertebrates of the Pacific
coast of North America. Doctoral Thesis, Univ. of Califor-
nia, Davis, Calif.

CaRLTON, J. T. 1979. Introduced invertebrates of San Fran-
cisco Bay. Pp. 427-444. In: T. J. Conomos, A. E. Leviton
& M. Benson (eds.), San Francisco Bay: the urbanized es-
tuary, investigations into the natural history of San Fran-
cisco Bay and delta with reference to influences of man.
Pacific Division, AAAS, San Francisco, Calif.

Epmunps, M. 1964. Eolid Mollusca from Jamaica, with de-
scription of two new genera and three new species. Bull.
Mar. Sci. Gulf Carib. 14(1):1-32.

D. W. Behrens, 1984

GosLINER, T. M. 1980. The systematics of the Aeolidacea
(Nudibranchia: Mollusca) of the Hawaiian Islands, with
description of two new species. Pacific Sci. 33(1):37-77.

GosLINER, T. M. 1981. A new species of tergipedid nudi-
branch from the coast of California. J. Moll. Stud. 47:200-
205.

GosLInER, T. M. & R. J. GRIFFITHS. 1981. Description and
revision of some South African aeolidacean Nudibranchia
(Mollusca, Gastropoda). Ann. S. Afr. Mus. 84(2):105-150.

GosLINER, T. M. & S. V. MILLEN. 1984. Records of Cuthona
pustulata (Alder & Hancock, 1854) from the Canadian Pa-
cific. Veliger 26(3):183-187.

GosLINER, T. M. & G. C. WILLIAMs. 1970. The opistho-
branch mollusks of Marin County, California. Veliger 13(2):
175-180.

HAMANN, J. 1981. Range extensions of northeastern Pacific
opisthobranchs. Opisthobranch Newsletter 13(6):21.

HEDGPETH, J. W. (ED.) 1978a. The outer shores. Part 1. Ed
Ricketts and John Steinbeck explore the Pacific Coast. Mad
River Press Inc.: Eureka, Ca. 128 pp.

HEDGPETH, J. W. (ED.) 1978b. The outer shores. Part 2.
Breaking through. Mad River Press Inc.: Eureka, CA. 182

PP-

Hurst, A. 1967. The egg masses and veligers of thirty north-
east Pacific opisthobranchs. Veliger 9(3):255-288.

JAECKLE, W. 1983. Range extensions for two California cu-
thonids (Gastropoda: Nudibranchia) from Santa Catalina
Island. Opisthobranch Newsletter 15(11-12):53.

JAECKLE, W. 1984. The opisthobranch molluscs of Humboldt
County, California. Veliger 26(3):207-213.

LAMBERT, P. 1976. Records and range extensions of some
northeastern Pacific opisthobranchs (Mollusca: Gastropo-
da). Can. J. Zool. 54:293-300.

LANCE, J. R. 1966. New distributional records of some north-
eastern Pacific opisthobranchs (Mollusca: Gastropoda) with
description of two new species. Veliger 9(1):69-81.

Lone, S. J. 1969. Records of Trinchesia virens, Trinchesia ful-
gens and Placida dendritica from San Luis Obispo County,
California. Tabulata 2(4):9-12.

MacFARLAND, F. M. 1966. Studies of opisthobranchiate mol-
lusks of the Pacific coast of North America. Mem. Calif.
Acad. Sci. 6:xvi+546 pp., 72 pls.

Marcus, Er. 1958. Western Atlantic opisthobranchiate gas-
tropods. Amer. Mus. Novit. 1906:1-82.

Page 71

Marcus, Ev. 1972. On some opisthobranchs from Florida.
Bull. Mar. Sci. 22(2):284-308.

Marcus, Ev. & H. P. I. HuGHEs. 1974. Opisthobranch mol-
lusks from Barbados. Bull. Mar. Sci. 24(3):498-532.
McDonaLp, G. 1983. A review of the nudibranchs of the

California coast. Malacologia 24(1-2):114-276.

McDonaLp, G. & J. NYBAKKEN. 1980. Guide to the nudi-
branchs of California. American Malacologists, Inc.: Mel-
bourne, Florida. 72 pp.

MILLEN, S. V. 1983. Range extensions of opisthobranchs in
the northeastern Pacific. Veliger 25(4):383-3806.

MILLER, M. C. 1977. Aeolid nudibranchs (Gastropoda: Opis-
thobranchia) of the family Tergipedidae from New Zealand
waters. Zool. J. Linn. Soc. 60(3):197-222, 1 pl.

MILLER, R. L. 1969. Ascophyllum nodosum: a source of exotic
invertebrates introduced into west coast near-shore marine
waters. Veliger 12(2):230-231.

O’ DONOGHUE, C. H. 1922. Notes on the nudibranchiate Mol-
lusca from the Vancouver Island region. III. Records of
species and distribution. Trans. Roy. Canadian Inst. 14(1):
145-167, pls. 5 & 6.

ROBILLIARD, G. A. 1971. Range extensions of some northeast
Pacific nudibranchs (Mollusca: Gastropoda: Opisthobran-
chia) to Washington and British Columbia, with notes on
their biology. Veliger 14(2):162-165.

ROLLER, R. A. 1969. Nomenclatural changes for the new species
assigned to Cratena by MacFarland, 1966. Veliger 11(4):
421-423.

ROLLER, R. A. & S. J. LONG. 1969. An annotated list of
opisthobranchs from San Luis Obispo County, California.
Veliger 11(4):424-430.

STEINBERG, J. E. 1963. Notes on the opisthobranchs of the
west coast of North America—IV. A distributional list of
opisthobranchs from Point Conception to Vancouver Island.
Veliger 6(2):68-73.

Tuompson, T. E. & G. H. Brown. 1976. British opistho-
branch molluscs, Mollusca: Gastropoda, keys and notes for
the identification of the species. Synopsis of the British fauna
(new series), No. 8, Linn. Soc. London. 203 pp., 1 pl.

WILLIAMS, G. C. & T. M. GOSLINER. 1979. Two new species
of nudibranchiate molluscs from the west coast of North
America, with a revision of the family Cuthonidae. Zool. J.
Linn. Soc. 67:203-223.

The Veliger 27(1):72-80 (July 2, 1984)

THE VELIGER:
© CMS, Inc., 1984

The Morphology, Reproduction and

Ecology of the Commensal Bivalve

Scintillona bellerophon spec. nov.

(Galeommatacea)

DIARMAID O FOIGHIL anp ALLAN GIBSON

Department of Biology, University of Victoria,
Victoria, British Columbia V8W 2Y2, Canada

Abstract. Scintillona bellerophon spec. nov. is ectocommensal with the holothurian Leptosynapta
clarki (Heding, 1928) in Sooke Harbour, Vancouver Island, British Columbia. It is similar in form
and habit to Scintillona zelandicus (Odhner, 1924) and is a simultaneous hermaphrodite with a fecundity
of up to 3000 eggs. The young are brooded in the suprabranchial chamber and released as D-veligers.
Following a planktotrophic stage, settlement and subsequent attachment to the host species occurs. In
aquaria, attached animals locate deeper in the sediment than unattached specimens. Individuals may
live up to 4 years. Another galeommatacean bivalve, Mysella tumida (Carpenter, 1864), and two poly-
chaete species are associated with L. clarki in Sooke Harbor. Both S. bellerophon and S. zelandicus
are relatively less specialized than related bivalves ectocommensal on holothuroids.

INTRODUCTION

THE SUPERFAMILY Galeommatacea contains numerous
species that live in association with a large diversity of
host species. Some members of the genera Entovalva, De-
vonia, C'ycladoconcha, Montacuta, and Scintillona occur on
or in synaptid holothurian hosts (Boss, 1965). In Septem-
ber 1982, an intertidal population of an unidentified bi-
valve was found in Sooke Harbour, Vancouver Island,
British Columbia. Specimens recovered were attached ex-
ternally to the synaptid holothuroid Leptosynapta clarki
(Heding, 1928). The bivalve was identified as a new species
of Scintillona, and is the first record of this genus on the
Pacific coast of North or South America. It is similar in
form and habit to §. zelandicus (Odhner, 1924), but differs
in details of the shell, foot and mantle. Scintillona zelan-
dicus occurs off New Zealand to depths of 90 m (ODHNER,
1924) and intertidally as an ectocommensal attached to
the synaptid Trochodota dendyi Mortensen (MoRTON,
1957). Its morphology has been described from preserved
specimens by ODHNER (1924) and from live animals by
MorTON (1957), who also made behavioral observations.
Sceintillona stigmatica (Pilsbry, 1920) has been recorded off
Hawaii (PILSBRY, 1920), and attached to the echinoid
Brissus lateracarinatus (Leske) off Japan (YAMAMOTO &
HABE, 1974).

Galeommataceans exhibit a wide variety of reproduc-
tive specializations and are generally considered to have
the most complex reproductive patterns in the Bivalvia
(DEROUX, 1961; JENNER & McCrary, 1968; MorTon,
1976; OCKELMANN & Muus, 1978). There is no available
information concerning reproduction in Scintillona.
Therefore, aspects of the reproduction of S. bellerophon
spec. nov., as well as the morphology and ecology, are
described.

MATERIALS anp METHODS

Animals were sampled intertidally at Woodward Point
in Sooke Harbour (Figure 1). Sampling was carried out
monthly during spring tides from October 1982 to April
1983 as well as in June and September 1983. All speci-
mens of Leptosynapta clarki encountered were removed
from their burrows and examined in the laboratory with
a dissecting binocular microscope. Specimens of Sczntillona
bellerophon were removed from the holothuroids, mea-
sured with an ocular micrometer, and checked for the
occurrence of brooding. Individuals were fixed for light-
microscope histology in 4% glutaraldehyde (biological
grade), dehydrated in ethanol, embedded in Poly Bed 812,
sectioned at 1 wm and stained with Richardson’s stain
(RICHARDSON & JARRET, 1960). For scanning electron

D. O Foighil & A. Gibson, 1984

Page 73

SCALE (Km)

Figure 1

Location of Woodward Point, Sooke Harbour, British Columbia, type locality and study area of Scintillona bel-

lerophon spec. nov.

microscopy, specimens were fixed in a 3:1 mixture of 4%
glutaraldehyde and 1% osmium tetroxide in 3% NaCl
(SMITH, 1983), dehydrated in acetone, critical point dried,
gold coated, and viewed with a JEOL JSM-35 scanning
electron microscope.

SYSTEMATICS
Family GALEOMMATIDAE Gray, 1840

Genus Scintillona Finlay, 1927

Small shells, being rounded at both ends. Small tubercular
cardinal tooth in right valve; oblique cardinal in left, ex-
tending into a thin lamella. Resilium has a prominent
nymph (CHAVAN, 1969).

Type species: Scintillona zelandicus (Odhner, 1924) (by
original designation, Spaniorinus zelandicus Odhner, 1924).

_ Scintillona bellerophon
O Foighil & Gibson, spec. nov.

(Figures 1 to 14)

Specific characteristics: Umbone slightly posterior, mid-
mantle fold extended posterodorsally as three pairs of re-
tractable flaps; distal part of foot has prominent longitu-
dinal ciliated grooves.

Type location: Woodward Point, Sooke Harbour, Van-
couver Island, British Columbia, Canada (48°21'49’N;
123°42"54°W).

Holotype: British Columbia Provincial Museum, Victo-
ria, British Columbia (BCPM) 983-1617-1. Paratypes:
BCPM 983-1617-2, National Museum of Natural Sci-
ences, Ottawa (NMNS) 86701 and NMNS 86702 (Table
i)

RESULTS
Morphology

The valves are broadly elliptical (Figure 2) ranging up
to 4.4 mm in length. They are equivalve and non-equi-

Table 1

Shell dimensions (mm) of holotype and paratypes of Scin-
tillona bellerophon spec. nov.

Specimen Length Height Width
Holotype BCPM 983-1617-1 4.2 Doll Lod
Paratype BCPM 983-1617-2 2.1 1.5 0.7
Paratype NMNS 86701 Saf 2.4 1e2

Paratype NMNS 86702 3.3 2.2 1.1

Page 74

The Veliger,; VolS2773 Nom

Figure 2

Right valve of Scintillona bellerophon spec. nov. showing deposit (d).

Figure 3

Scintillona bellerophon spec. nov.: A. Hinge of left valve; B.
Ventral view of hinge; C. Hinge of right valve. d, depression; el,
external ligament; il, internal ligament; lv, left valve; rv, right
valve.

lateral, the orthogyrous umbone being slightly posterior
(% of the total shell length from the anterior) and having
a prominent, rounded prodissoconch-2. The valve margins
are excurved, particularly anterodorsally and to a lesser
extent posterodorsally. As a result, the valves cannot be
firmly apposed.

The outer shell surface appears slightly nacreous and
is usually whitish in color. Fine concentric lines are pres-
ent on the other outer shell surface, and in some individ-
uals distinct growth checks are present. Many individuals
display a prominent patch of dark brown or purple de-
posit (Figure 2) similar to that occurring on numerous
other galeommataceans commensal with burrowing hosts
(GAGE, 1966; KAWAHARA, 1942; MorTON, 1957; PILSBRY,
1920; PONDER, 1968). A prominent periostracal edge is
present, especially anteriorly. Numerous pits (visible at
x 40 magnification) occur on the inner surface of the shell.
The pallial line is entire, and the anterior and posterior
adductor muscle scars are of a similar size.

The external ligament is weak and posterior, and the
internal ligament is moderately developed and has a
marked nymph. In the left valve, a single, more robust
anterior tooth occurs, and is connected to a lateral ridge
(Figure 3A) that articulates with a corresponding shallow
depression in the right valve (Figure 3C). A single peg-
like tooth is present in the right valve (Figure 3C), the
base of which is continuous with a weak ridge delineating
the shallow depression. Both teeth are cyclodont and in-
terlock across the hinge line (Figure 3B).

D. O Foighil & A. Gibson, 1984

Figure 4

Scintillona bellerophon spec. nov. General morphology (left valve
and left mantle fold removed). aa, anterior adductor muscle; f,
foot; g, gill; lp, labial palps; mf, mid-mantle fold extension; p,
periostracum; pa, posterior adductor muscle; t, inner mantle fold
tentacles.

The inner fold of the mantle is fused posteroventrally
to separate an anterior pedal (inhalent) opening from a
narrow, slit-like posterior exhalent siphon. Anterior to the
fusion, the inner fold has a scalloped margin. Numerous
tentacles (20-30) are present on the region of fusion and
surrounding the exhalent siphon. The edge of the mid-
mantle fold bears small papillae, except dorsoposteriorly.
Here the mid-fold is hypertrophied into three flaps on
either side which, when relaxed, extend to cover the shell
surface dorsal to the exhalent siphon. Ridges are present
on the inner face of these flaps, but they do not display
ciliary activity. The outer mantle fold is small and is at-
tached to the periostracal edge.

The homorhabdic eulamellibranchiate ctenidia cover the
visceral mass, with the gill axis (orientated at approxi-
mately 45° to the long axis) extending from under the
umbone to the exhalent opening (Figure 4). Inner and
outer demibranchs are present, as in other galeommatids
(POoPHAM, 1940); the outer demibranchs, however, are
much reduced in size, especially anteriorly. A food groove
is present in the inner demibranch only.

Ascending and descending lamellae are present in both
demibranchs. In the outer demibranch, the ascending la-
mellae extend dorsally to fuse with the mantle above the
gill axis. The inner demibranchs fuse behind the foot. Few
interlamellar junctions occur, and these are restricted to
the extreme posterior of the gill.

Gill ciliation is similar to that described for other gale-
ommatids (JUDD, 1971; PopHAM, 1940). Particles are
passed ventrally along the ascending lamellae of the outer
demibranchs and dorsally via the descending lamellae to
the gill axis. Here the particles are propelled anteriorly
and then ventrally toward the labial palps. Ciliary cur-
rents on both lamellae of the inner demibranchs pass par-

Page 75

ticles to the ventral food groove, and hence to the labial
palps.

The foot is large and laterally compressed, and has two
distinct parts (Figure 4). The distal portion is thickened
and opaque, and has a pleated surface with 20-30 lon-
gitudinal, densely ciliated grooves. The proximal part is
thinner, smooth-surfaced, and more translucent. The cilia
in the distal grooves become active only when the foot is
engaged in locomotion. Particles are passed dorsally along
these grooves, bound in a mucous sheet, and pushed over
the outer mantle fold when the foot contracts. A byssal
gland is present at the posteroventral end of the distal
section of the foot.

Locomotion is achieved as in Scintillona zelandicus
(MortTon, 1957). The distal part of the foot is extended
and applied laterally to the substratum. This is followed
by serial contractions of the anterior, then posterior, pedal
retractor muscles, which rock the rest of the body forward
onto the foot. Byssal attachment is accomplished by adopt-
ing an upright position, contact with the substratum being
made by the slender base of the foot onto which the byssal
gland opens.

Waste particulate material in the mantle cavity is ex-
pelled anteriorly by valve contractions, or ventrally by
mantle ciliary rejection tracts between the foot and the
region of mantle fusion. Fecal pellets and brooded veliger
larvae exit via the exhalent siphon.

The gonad develops along the ventral and posterior
margins of the digestive gland. Sczntillona bellerophon is
a simultaneous hermaphrodite, with sperm and eggs de-
veloping within separate follicles (Figure 5). In individ-
uals less than 2.5 mm in length, the gonad is predomi-
nantly male. The ovotestis is connected to the
suprabranchial chamber by a pair of ciliated gonoducts,
one on each side. Some specimens contained a few spo-
rocysts of an unidentified helminth parasite embedded in
the gonad.

Reproduction

Fertilization occurs in the suprabranchial chamber and
embryos are brooded there until they have reached the
D-veliger (straight hinge) stage of development. They are
then released and assume a planktotrophic existence until
settlement. It is not known if Scintillona bellerophon self-
fertilizes.

Brooding individuals were observed in the November
1982 and February—September 1983 samples, with the
highest frequency of brooders in March and April of 1983
(38% and 10% respectively). Samples from the other
months showed less than 2% of the animals brooding.

Uncleaved eggs observed in the gill chamber had under-
gone two reduction divisions (Figure 7) and are about 70
um in diameter (X = 69.9 + 1.1 SE, n = 40). The fecun-
dity of three specimens examined ranged from 1965 (2.95
mm valve length) to 2912 (3.5 mm valve length).

The sperm heads are rodlike in shape and are 10 um

Page 76

he Veliger; Volki27-ahiomst

Explanation of Figures 5 to 7

Scintillona bellerophon spec. nov. Figure 5. Light micrograph of the ovotestis. 0, oocyte; s, spermatids. Figure 6.
Light micrograph of sperm. Figure 7. Light micrograph of ovum. pb, polar bodies.

in length (Figure 6). They are generally similar to, though
considerably shorter than, the eupyrene sperm of Mysella
bidentata (Montagu, 1803) (OCKELMANN & Muus, 1978).
The sperm aggregate when removed from the gonad,
forming large spherical masses as reported in M. bidentata
by OCKELMANN & Muus (1978).

Embryonic development from early cleavage stages to
larval release took 12 days at 10°C in aquarium-held spec-
imens (ambient water temperature in March 1983 was
10.3°C). No encapsulating fertilization membrane was
apparent in early embryos (Figure 8). Ciliation appears
at the trochophore stage (Figure 9), and the embryos are
capable of weak swimming movements when removed from
the gills. Early developmental stages are circulated by the
adult around the gill chamber. As the embryos grow and

develop valves, the gills become distended, inhibiting fur- —

ther embryo movement. Mature D-veligers have a rust-
colored hinge line, which gives brooding animals a pink
internal coloration as in Montacuta percompressa Dall, 1899

(CHANLEY & CHANLEY, 1970). The prodissoconch-1 of
Scintillona bellerophon has a pitted surface (Figure 10).
It also shows faint radial lines towards the margin as
described by REES (1950) for the Galeommatacea (Ery-
cinacea) and Lucinacea.

Mature D-veligers (Figure 11) are released through the
exhalent siphon in a few pulses. They immediately com-
mence vigorous swimming. Mean valve length at release
was 130 wm + 2.1 SE, and mean valve height was 97
wm + 2.5 SE (n= 40) (Figure 11). The duration of the
larval stage was not determined.

Settlement occurs when the larvae are between 300 and
375 wm in length. Newly metamorphosed juveniles with
little or no dissoconch growth were found attached to Lep-
tosynapta clarki (Figure 12). In aquaria, dislodged juve-
niles were frequently picked up by the feeding tentacles
of the holothuroid and passed onto the host’s body surface.
Many of these reattached by byssal threads at the base of
the tentacles. This is in contrast to M. percompressa where

D. O Foighil & A. Gibson, 1984 Page 77

Explanation of Figures 8 to 13

Scintillona bellerophon spec. nov. Figure 8. Scanning electron micrograph (SEM) of early morula. Figure 9. SEM
of trochophore. Figure 10. SEM of D-veliger, before release. Figure 11. Light micrograph of newly released
D-veliger. Figure 12. Newly settled Scintillona bellerophon attached to Leptosynapta clarki. Figure 13. SEM of

juvenile. di, dissoconch; pr, prodissoconch.

|
|
|
| I
OB 1% 24 32
Length [mm] »

1.6 24
Length [mm] >

The Veliger, Vol- 277 Now

0.8 16 24
Length [Lmm] )

Length [mm] >

Figure 14

Size-frequency distributions from pooled monthly samples of Scintillona bellerophon spec. nov. at Woodward
Point. A. October, November, and January 1982 (n = 147); B. January, February, and March 1983 (n = 84); C.
April and June 1983 (n = 108); D. September 1983 (n = 99).

laboratory-raised juveniles did not attach to their synaptid
host (CHANLEY & CHANLEY, 1970).

Ecology

The sediment at Woodward Point is a coarse silt
(McDERMID, 1983) and has a prominent algal cover of
Ulva in summer months. A narrow spit projects across the
mouth of Sooke Harbour (Figure 1), and protects the
study site from direct wave action (MCDERMID, 1983).
Specimens of Leptosynapta clarki were present from mid
to low tide levels, and, in November 1982, occurred in a
mean density of 78/0.1 m? (estimated from 13 randomly
taken 5.5-cm diameter cores). The holothuroids were found
to a depth of 8-10 cm in the sediment, and occupied semi-
permanent burrows as they moved slowly through the
substratum. In September 1983, 57% of the Leptosynapta
recovered (n = 68) had =1 attached Scintillona bellero-
phon. The mean number of bivalves per host was 1.69 +

1.05 SE (n = 39), and the maximum occurrence on a sin-
gle holothuroid was 6. Typically S$. bellerophon attached
to the anterior half of Leptosynapta in a forward-facing
orientation. Adhesion was achieved either by fine byssal
threads, or more loosely by the lateral apposition of the
extended foot to the integument of the host.

In aquaria, bivalves removed from their hosts usually
reattached to any available Leptosynapta. Specimens of
Scintillona bellerophon placed in aquaria without holo-
thuroids remained at the surface or burrowed superfically
in the sediment (mean depth = 4 mm + 0.2 SE, n= 10).
Upon the introduction of Leptosynapta and subsequent
attachment, individuals of S$. bellerophon were found at
significantly greater depths (x = 18 mm + 6 SE, n= 8,
P < 0.001), probably as a result of the holothuroid’s bur-
rowing activity. The burrowing and ventilating activities
of the holothuroids increased the depth of the lighter col-
ored (oxygenated) sediment zone from 2-3 mm to 45-50
mm.

D. O Foighil & A. Gibson, 1984

Three other invertebrate species were frequently found
in Leptosynapta clarki burrows. Two were polychaetes,
Harmathoe lunulata (delle Chiaje) and Pholoe minuta (Fa-
bricius, 1780); the third was another galeommatacean bi-
valve, Mysella tumida (Carpenter, 1864). Both polychaetes
were free in the burrow and tended to cling to the host
holothurian. Mysella tumida was never seen to attach to
the host, but occurred in the oxidized sediment layer im-
mediately surrounding the burrow.

Some of the larger individuals of Scintillona bellero-
phon exhibited 3 growth-arrest rings on their valves, in-
dicating that they may live up to 3-4 years of age. The
first growth-arrest ring is formed at a valve length of 1.8-
2.6 mm, the size attained by the first year class (Y,) by
their first winter (Figure 14). In 1983, settlement com-
menced in April, peaked in June, and continued at a re-
duced rate throughout the summer (Figure 14). By Sep-
tember, individuals recruited in April/June had grown
by approximately 1.3 mm in length to reach 1.6-2.1 mm.
It would appear that they reach sexual maturity the fol-
lowing spring at a length of 2.4-3.0 mm.

Leptosynapta clarki occurs off the Pacific coast of North
America from the Queen Charlotte Islands to Pacific
Grove, California (BROOKS, 1973). Scintillona bellero-
phon is, to date, known only from Sooke Harbour. Two
nearby sites with dense populations of the holothuroid,
Bamfield Inlet (Vancouver Island) and False Bay (San
Juan Island, Washington State), apparently do not con-
tain this species (A. Gibson, personal observation, and R.
D. Burke, personal communication, respectively). In an
ecological study carried out on the Sooke population of
Leptosynapta in 1973, BRooxs (1973) did not encounter
any S. bellerophon. This implies that the bivalve colo-
nized this site 4-10 years ago and has since built up a
considerable population density.

DISCUSSION

Scintillona bellerophon is similar to S. zelandicus in
both morphology and mode of life. At least three distinct
morphological differences, however, exist between the two
(based on ODHNER’s (1924) and MorTON’s (1957) de-
scriptions and the examination of three specimens of S.
zelandicus); these are sufficient to give S. bellerophon a
separate species designation. In S. bellerophon the (A)
umbone is slightly posterior, the anterodorsal margin being
as a result higher than the posterodorsal margin (in S.
zelandicus the umbone is slightly anterior (personal ob-
servation) and the posterodorsal margin is higher), (B)
mid-mantle fold is extended posterodorsally into three re-
tractable flaps on either side (not extended in S. zelandi-
cus), (C) distal part of the foot contains numerous and
prominent longitudinal ciliated grooves (present in re-
duced form in S. zelandicus).

Of the four species found with Leptosynapta clarki, Scin-
tillona bellerophon is probably the most intimately asso-
ciated. To the other species, the burrow may only serve

Page 79

as a temporary refuge or feeding site. Pholoe minuta was
frequently found outside the burrows, and Mysella tumida
also occurs as an ectocommensal of the polychaete Meso-
chaetopterus taylori (O Foighil, personal observations).
Harmathoe lunulata has previously been recorded in as-
sociation with L. clarki (BROOKS, 1973) and, in the North
Atlantic, with L. inharens (O. Fr. Miller) (MORTENSEN,
1927). This is the first record of P. minuta and M. tumida
living as commensals. The ventilating activities of Lepto-
synapta enable these polychaetes and the small, practically
siphonless bivalves to live at depth in the substratum by
positioning in or around the burrow. This may result in
reduced predation pressure (OCKELMANN & Muus, 1978).
Leptosynapta clarki does not seem to benefit from the as-
sociation in any obvious manner.

As well as showing a trend toward commensalism, the
members of the Galeommatacea demonstrate various de-
grees of shell reduction, mid-mantle fold hypertrophy, and
reproductive complexity (MORTON, 1976). When Scintil-
lona bellerophon and S. zelandicus are compared in these
respects with other galeommatacean bivalves ectocommen-
sal with synaptid holothurians, they are found to be rel-
atively unspecialized. In Devonia perriert (Malard, 1903),
which occurs on Leptosynapta inharens, the valves are much
reduced, hinge dentition is absent, and the mid-mantle
fold extends to almost completely cover the shell surface
(ANTHONY, 1916). Montacuta percompressa, which also
occurs on L. inharens (BATESON, 1923), shows secondarily
developed sexual dimorphism, in which parasitic, shell-
less males occur within the mantle cavity of the female
(JENNER & McCrary, 1968). This hints that, in evolu-
tionary terms, both S. bellerophon and S. zelandicus are
relative newcomers to this particular ecological niche.

For all ectocommensals, adhesion to the host is obvious-
ly important. Scintillona bellerophon and S. zelandicus
achieve this by two means, apposition of the laterally com-
pressed foot and ventral attachment by byssus. In the oth-
er bivalves ectocommensal on synaptids, foot morphology
varies from the relatively unspecialized condition in De-
vonia oskimai (KAWAHARA, 1942) to that of D. perrieri. In
the latter species, the foot is dorsoventrally compressed
and acts as a sucker when attached to the host, Leptosy-
napta inharens. The byssal gland opens ventrally, and the
animal may attach by byssus or by foot adhesion
(ANTHONY, 1916; POPHAM, 1940). This would seem to be
a more efficient situation than that found in S. bellero-
phon and, presumably, in S. zelandicus, because changing
from foot to byssal adhesion does not involve a re-orien-
tation of the foot. In S. bellerophon, contact depends on
the relatively narrow, ventral surface until byssal attach-
ment is achieved.

Synaptid holothurians, in common with many other
burrow-constructing benthic invertebrates, create micro-
environments in sediments that are colonized by a variety
of associated species. Several galeommatacean bivalves have
been found occurring ectocommensally on synaptid holo-
thurians (Boss, 1965). In the northeastern Pacific, Scin-

Page 80

tillona bellerophon is the representative ectocommensal
species, exploiting the ecological niche available in Lep-
tosynapta clark: burrows.

ACKNOWLEDGMENTS

We thank Dr. A. R. Fontaine and Dr. R. D. Burke
for the use of facilities. J. E. Morton verified the identi-
fication and supplied three specimens of Scintillona Ze-
landicus. R. T. Abbott gave useful advice. Francisco Per-
eira Da Costa kindly drew the figures, and earlier drafts
were critically read by Dr. R. G. B. Reid, Dr. A. R.
Fontaine, Betsy Day, and Richard Gustafson. This work
was supported by a University of Victoria Graduate Fel-
lowship to D. O Foighil.

LITERATURE CITED

ANTHONY, R. 1916. Contribution a l'étude de l’Entovalva (Syn-
apticola) perriert Malard, mollusque acéphale commensal
des synaptes. Arch. Zool. Exp. Gén. 55:375-391.

BaTEson, G. 1923. (no title). Proc. Malacol. Soc. Lond. 15:
266-267.

Boss, K. J. 1965. Symbiotic erycinacean bivalves. Malacologia
3(2):183-195.

Brooks, E. J. 1973. Some aspects of the taxonomy and biology
of the genus Leptosynapta (Holothuroidea) in British Co-
lumbia. Master’s Thesis, University of Victoria. 95 pp.

CHANLEY, P. & M. H. CHANLEY. 1970. Larval development
of the commensal clam Montacuta percompressa Dall. Proc.
Malacol. Soc. Lond. 39:59-67.

CHAVAN, A. 1969. Superfamily Leptonacea Gray, 1847. In: R.
C. Moore (ed.), Treatise on invertebrate paleontology, N,
Mollusca. Geological Society of America and University of
Kansas Press. 6:518-537.

Deroux, G. 1961. Rapports taxonomiques d’un leptonacé non
décrit Lepton subtrigonum Jeffreys (nomen nudum 1873). Cah.
Biol. Mar. 2:99-153.

GaGE, J. D. 1966. Observations on the bivalves Montacuta
substriata and M. ferruginosa, commensals with spatangoids.
J. Mar. Biol. Assoc. U.K. 46:49-72.

JENNER, C. E. & A. B. McCrary. 1968. Sexual dimorphism

The Veliger, Volo 27a Nom

in erycinacean bivalves. Amer. Malacol. Union Ann. Bull.
Rep. 35:43.

Jupp, W. 1971. The structure and habits of Divariscintilla
maoria Powell (Bivalvia: Galeommatidae). Proc. Malacol.
Soc. Lond. 39:343-353.

Kawauara, T. 1942. On Devonia oshimai sp. noy., a commen-
sal bivalve attached to the synaptid Leptosynapta ooplax. Ve-
nus 11:153-164.

MatarpD, A. E. 1903. Sur un lamellibranche nouveau, parasite
des synaptes. Bull. Mus. Hist. Natur. Paris 9:342-346.
McDermip, M. A. 1983. Aspects of the reproductive biology
of the viviparous, apodous holothurian Leptosynapta clarki
(Heding). Unpubl. B.Sc. Thesis, University of Victoria. 44

PP-

Morton, B. 1976. Secondary brooding of temporary dwarf
males in Ephippodonta (Ephippodontina) oedipus sp. nov.
(Bivalvia: Leptonacea). J. Conch. 29:31-39.

Morton, J. E. 1957. The habits of Scintillona zelandica
(Odhner) 1924 (Lamellibranchia: Galeommatidae). Proc.
Malacol. Soc. Lond. 32:185-188.

MorTENSEN, T. 1927. Handbook of the echinoderms of the
British Isles. Oxford University Press. 471 pp.

OCKELMANN, K. W. & K. Muus. 1978. The biology, ecology
and behavior of the bivalve Mysella bidentata (Montagu).
Ophelia 17(1):1-93.

ODHNER, N. H. 1924. New Zealand Mollusca. Jn: Papers
from Dr. Mortensen’s Pacific expedition. Vidensk. Medd.
fra Dansk naturh. Foren. Bd., 77 pp.

Piussry, H. A. 1920. Marine molluscs of Hawaii. Proc. Acad.
Natur. Sci. Philadelphia 8:296-326.

PONDER, W. F. 1968. Three commensal bivalves from New
Zealand. Rec. Dom. Mus. Wellington 6(9):125-131.
PopHaM, M. L. 1940. The mantle cavity of some of the Ery-
cinidae, Montacutidae and Galeommatidae with special ref-
erence to the ciliary mechanisms. J. Mar. Biol. Assoc. U.K.

24:549-587.

Rees, C. B. 1950. The identification and classification of la-
mellibranch larvae. Hull Bull. Mar. Ecol. 3(19):73-104.

RICHARDSON, K. C. & L. JARRET. 1960. Embedding in epoxy
resins for ultrathin sectioning in electron microscopy. Stain.
Tech. 35:313-323.

SmITH, T. B. 1983. Tentacular ultrastructure and feeding be-
haviour of Neopentadactyla mixta (Holothuroidea: Dendro-
chirota). J. Mar. Biol. Assoc. U.K. 63:301-311.

YAMAMOTO, T. & T. HaBe. 1974. Scintillona stigmatica (Pils-
bry) new to Japan. Venus 33(3):116.

The Veliger 27(1):81-89 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

A New Species of

Leptonacean Bivalve from off Northwestern Peru

(Heterodonta: Veneroida: Lasaeidae)

JOSEPH ROSEWATER

Department of Invertebrate Zoology, National Museum of Natural History,
Washington, D.C. 20560

Abstract. A new species of leptonacean bivalve, Pseudopythina muris, has been found in the respi-
ratory cavity of a polychaete, Aphrodita, from off northwestern Peru (R/V Anton Bruun SEPBOP
cruise 16, sta. 625a; cruise 18B, sta. 764). Mature clams are strongly crescent-shaped and are attached
by fine byssal threads to elytra of Aphrodita. Young stages are moderately equilateral, but show pro-
gressive changes in shape until the adult inequilateral condition is achieved. Characteristics of shell
and soft part morphology indicate placement of this species in the superfamily Leptonacea, family
Lasaeidae. The unusual shape may be an adaptation to life in the respiratory cavity of Aphrodita.
Examinations of this and other oddly shaped Leptonacea show that some of these anatomical modifi-
cations are functional adaptations to the hosts or commensals with which they are associated.

INTRODUCTION

THE R/V Anton Bruun carried out nine cruises during
the International Indian Ocean Expedition (IIOE, 1963-
1964). In 1965, upon returning to the western hemisphere
(cruise 10), the Anton Bruun began the Southeastern Pa-
cific Biological Oceanographic Program (SEPBOP, 1965-
1966), during which eight cruises were undertaken (cruis-
es 11-18, the last consisting of parts A and B). During
cruises 16 and 18B, trawls were made in 90-133 m, off
northwestern Peru. Invertebrates captured were forward-
ed to the Smithsonian Institution’s Oceanographic Sorting
Center, Washington, D.C., where they were sorted and
initial identifications were made. Scale worms, Aphrodi-
tidae, are normally sent to M. H. Pettibone, National
Museum of Natural History, for study. However, since
small bivalves were found clinging to ventral surfaces of
some specimens, they were sent first to me. The small
bivalves were noted externally and, in addition, upon pal-
pation, hard bodies were felt in the normally soft scale
worms. The worms were X-rayed revealing the crescent-
shaped clams visible in Figure 1A-F. I dissected the scale
worms (Aphrodita japonica Marenzeller, 1879) revealing
a number of the bivalves, ranging from tiny rather nor-
mally shaped specimens, as small as 1 mm in length, to
larger crescent-shaped individuals, 10.9 mm in length.
Comparison with collections and the literature revealed
no known species exhibiting the characteristics of the bi-

valves found in the respiratory cavity of Aphrodita (see
ROSEWATER, 1983). They are herein described as a new
species belonging to the family Lasaeidae.

Boss (1965) reviewed the commensal relationships of
the ‘“Erycinacea” (now Leptonacea; see CHAVAN, 1969,
and Boss, 1982; also see Acknowledgments, herein) and,
in an addendum to his paper, mentioned that PONDER
(1965) had described the New Zealand leptonacean bi-
valve Arthritica hulmei attached to the elytra of Aphrodita,
a relationship apparently very similar to the one reported
here. Both PETTIBONE (1953) and NARCHI (1969) de-
scribed the relationship of the east Pacific leptonacean
bivalve species Pseudopythina rugifera (Carpenter, 1864)
with Aphrodita japonica, the same worm host involved in
the present study. The former was said by Pettibone to
occur in the respiratory cavity of the worm, and both
Pettibone and Narchi report it to attach externally. It is
also known to attach to the crustacean Upogebia.

The new species is reminiscent of another crescent-
shaped bivalve, Curvemysella paula (Adams, 1856), from
the Indo-Pacific, although the two differ in details of hinge
structure, and in mature stages the new species possesses
a more strongly crescent-shaped shell that is equivalve,
strongly hypertrophied posteriorly, and narrowed ante-
riorly. Young stages are moderately equilateral, but show
progressive changes in shape until the adult inequilateral
condition is assumed (see Figure 2).

Page 82

The Veliger, Vol. 27, No. 1

Figure 1

X-rays showing Pseudopythina muris spec. nov. in situ, in respiratory cavity of Aphrodita japonica; larger clams are
nearer the posterior end of worm (worms 4-5 cm in length). A-C. Same individual from different angles. D-E.
Different individual. F. Another individual. Note in E and F, tiny clams scattered through worm’s respiratory

cavity.

TAXONOMY
Family Lasaeidae Gray, 1847
Gray, J. E. 1847:192 [as Lasiadae].

In a recent review of the phylum Mollusca, Boss (1982)
characterized members of the bivalve family Lasaeidae
(Subclass Heterodonta: Order Veneroida: Superfamily
Leptonacea) as being equivalve, variously shaped, thin,
fragile, compressed to more-or-less inflated, umbos sub-
median, usually less than 20 mm in length, dimyarian,
adductors subequal, pallial line simple, hinge variable,
antero-posterior respiratory-feeding current, with incur-

rent and excurrent mantle openings located so as to ac-
commodate such a flow. Ctenidia are reduced, limited to
inner demibranchs; individuals are monoecious, with evi-
dence of brooding of young in mantle cavity; frequently
commensal or parasitic. These features are characteristic
of the bivalves found off northwestern Peru in Aphrodita,
and they are, therefore, included in the Lasaeidae.
Although adult specimens of the new species assume an
exaggerated crescent shape, their shells in many ways re-
semble those of members of only one generic group so far
as I have been able to determine, the genus Pseudopythina
Fischer, 1878. They share a number of similarities with

J. Rosewater, 1984

ee

=I“

Figure 2

A-E show changes in outline of Pseudopythina murts spec. nov.
shells from equilateral to inequilateral as growth progresses.

species assigned to that group, including a tendency to
associate with Aphrodita and certain crustaceans.

Pseudopythina Fischer, 1878

Pseudopythina FISCHER, 1878:178; type species by monotypy,
Kellia macandreun FISCHER, 1867:194.

Pseudopythinia LOCARD, 1892:317 [invalid emendation for
Pseudopythina Fischer, 1878]; LocarD, 1898:303.

The type species, Kellia macandreun Fischer, is an in-
habitant of southern European seas. Its characteristics were
pointed out by CHAVAN (1969) in his description of Pseu-
dopythina: “transverse trigonal, very inequilateral, ante-
riorly attenuated and elongate; enlarged and rounded
backward [posteriorly], smooth.” Hinge teeth are simple
and consist of a single curved, projecting cardinal tooth in
either valve, just beneath the umbos, posterior to which is
located a well developed, and mostly internal ligament.
The other cardinals and anterior and posterior lateral teeth
are much reduced and limited to weak thickenings of the
dorsal valve margins. Cardinal teeth of the type species,
P. macandrewi, are more heavily developed than in other
species examined, and may be supported by basal thick-
ening. The anterior adductor muscle scar is usually elon-
gate, the posterior more rounded. A pallial line is evident
in some species, usually well inset from shell margins.
Externally, shells are smooth with a thin, often wrinkled
periostracum, which may be reflected onto the interior
edge of the shell. Faint radiating rays are present and are
most noticeable at the ventral margin. Shells often show
a ventral embayment developed variously in different
species; strongest in the new species described herein.
Pseudopythina compressa Dall, 1899, shows little evidence
of such an embayment, prompting DALL (1899) to suggest
its normal form results from the lack of a commensal
relationship, although OLDROYD (1924) stated that all
Pseudopythina are commensals.

The anatomy of Pseudopythina was described and il-

Page 83

lustrated by NARCHI (1969) in his study of the species P.
rugifera (Carpenter, 1864) and verified by me through
examination of the new species from off Peru. I disagree
with the transfer by ABBOTT (1974) of the West Coast
species previously assigned to Pseudopythina Fischer to
Orobitella Dall, 1900. The characteristics of Pseudopythina
macandreuwi are quite different from those of the type
species of Orobitella, O. floridana Dall, 1899, with its reg-
ular and often deeply incised concentric sculpture, large
rounded to squarish adductor muscle scars, posteriorly
displaced umbos, and pellucid shell, or from the similar
appearing Neaeromya Gabb, 1873 (type species, N. quad-
rata Gabb, 1873), with which both ABBOTT (1974) and
BERNARD (1983) ally Orobitella.

There are representatives of Pseuwdopythina in the sev-
eral marine faunal regions with the exception of the west
Atlantic. An abbreviated catalogue of the Recent species
follows. Until the anatomy of each species is studied and
compared, however, it will not be possible to state with
certainty whether or not these species are really related.

East Atlantic

Pseudopythina macandrewi (FISCHER, 1867):194 (Nord
de Espagne; bassin d’Arcachon (Gironde) [Bay of Bis-
cay, France]); not in Journal de Conchyliologie Type Col-
lection (FISCHER-PIETTE, 1950); may be in British Mu-
seum (NH) (DANCE, 1966); syntypes (?) ex MacAndrew
in Jeffreys Collection, USNM 170637, from Vigo Bay,
Spain.

Remarks—This is the type species of Pseudopythina
Fischer, 1878. It is listed as a junior synonym of P. setosa
(Dunker, 1864) by JEFFREYS (1881), LocarD (1898),
CHAVAN (1969), NoRDSIECK (1969), and QUILEs (1973).
The last four authors seem to have ignored the statement
by JEFFREYS (1882) that Dunker’s species is the young of
Coralliophaga lithophagella (Lamarck, 1819), a member of
the Trapeziidae (see LAMy, 1920:283). The name speci-
fied by JEFFREYS (1882) as having priority over P. ma-
candrewi, Sportella caillati Conti, 1864, attributed by the
latter to ““Deshayes, 1852,” apparently is a manuscript
name. The name was validly introduced by DESHAYES
(1860:596) for an unrelated fossil. So far as I can deter-
mine, Fischer’s name, Kellia macandrewy, is the oldest val-
id taxon for this entity.

Other east Atlantic species assigned to Pseudopythina
are:

Pseudopythina geoffroyi geoffroy: (Payraudeau, 1826),
NORDSIECK (1969:90)

Pseudopythina geoffroy: complanata (Philippi, 1836),
NORDSIECK (1969:90).

Remarks—lI have been able to find no information on
commensalism in these species.

East Pacific

Of the several east Pacific species included in Orobitella
Dall, 1900, by ABBotT (1974), the only three that seem

Page 84

The Veliger, Vol. 27, No. 1

to be referable to Pseudopythina are listed below. The
remainder probably belong in Orobitella or other groups.
Their ultimate placement will depend on analysis of an-
atomical relationships impossible at this time.

Pseudopythina rugifera (CARPENTER, 1864):602, 643
(Puget Sound; syntypes USNM 4445); CARPENTER, 1865:
Die

Remarks—Although this species is dated from Carpen-
ter, 1864, without a prior concept it is difficult to recognize
without reference to the type specimens. His 1865 descrip-
tion is much more complete. NARCHI (1969), who has
made the most intensive studies on this species to date,
discussed its anatomy thoroughly and also its commensal
relationships with the crustacean Upogebia and the poly-
chaete Aphrodita. The species is very similar in its general
appearance to the new species being described herein, al-
though lacking the extreme crescent shape. The species P.
rugifera is distributed from Alaska to Baja California,
Mexico, according to ABBOTT (1974). The following are
synonyms of P. rugifera according to BERNARD (1983:32):
Lepton rude Whiteaves, 1880, Sportella californica Dall,
1899, and Pseudopythina myaciformis Dall, 1916.

Pseudopythina stearnsu (DALL, 1899):879, 885 (Gulf of
California; holotype USNM 73701). BERNARD, 1983:32.

Remarks—Sportella stearnsu Dall, 1899, is placed by
BERNARD (1983, as Neaeromya) close to P. rugifera and P.
compressa. The unique holotype has a much heavier shell
and cardinal teeth than the other West Coast species, more
reminiscent of the type species, Pseudopythina macandrewi
(Fischer, 1867).

Pseudopythina compressa DALL, 1899:880, 888 (south of
Nunivak Island [SW of Hagemeister Island, USFC sta.
3305], Alaska; holotype USNM 107855).

Remarks—This species is less inflated and has a more
rounded outline than P. rugifera, but has the characteristic
single cardinal tooth and ligament of Pseudopythina. DALL
(1899) pointed out that, due to its uniform shape, it prob-
ably is not a commensal species. Most distributional rec-
ords for this species are from northern waters, Alaska,
north of the Aleutian Islands, south to British Columbia,
in from 10 to 150 m (BERNARD, 1983). The record men-
tioned by ABBoTT (1974), off Acapulco, is based on USNM
210171, USFC station 3422, in 258 m, a typical specimen.
The species is listed by HABE (1977) as a Squillaconcha,
(see below).

Indo-Pacific

Subgenus Squillaconcha KURODA & HaBE, 1971:627,
404; type species by original designation: Kellia subsinuata
Lischke, 1871.

Remarks—This taxon was proposed at subgeneric rank
to contain Japanese species formerly assigned to Pseudo-
pythina. Its justification seems to be based mainly on the
geographical and host differences.

[these 5 mm SS)

Figure 3

Shell of Pseudopythina muris spec. nov. Upper figure: exterior.
Lower figure: interior of shell showing anterior (right) and pos-
terior adductor muscle scars and characteristics of the hinge.

Pseudopythina (Squillaconcha) subsinuata (LISCHKE,
1871):43 (Japan; type in Academy of Sciences, Lenin-
grad).

Remarks—This species often is found as a commensal
on mantis shrimps. It is distributed in Japan on the is-
lands of Honshu, Shikoku, and Kyushu. According to
HaBE (1964) it incubates its larvae in the branchial cham-
ber.

Pseudopythina (Squillaconcha) sagamiensis HABE, 1961:
151 (Zushi City, Kanagawa Prefecture, Japan; type in
National Science Museum, Tokyo).

Remarks—Pseudopythina sagamiensis was added to
Squillaconcha by HABE (1977), who also included P. com-
pressa Dall, 1899, which is here referred to Pseudopythina
sensu stricto. Pseudopythina sagamiensis is said to differ
from P. subsinuata in being more narrowly elongate and
smaller in size than the former. Its commensal relation-
ships apparently are unknown.

J. Rosewater, 1984

\ <

We PRRRRE

[ztcrwes 5 mm
Figure 4

Jo
\\ AK AS
\\ \ \\\ \

Page 85

WN .
SS SALSA

Anatomy of Pseudopythina muris spec. nov. and detail of hinge of right shell valve (see Abbreviations listed at end

of text).

Pseudopythina muris Rosewater,
spec. nov.

(Figures 3, 4; Table 1)

Description: Shell reaching 10.9 mm in length; mature
individuals have a crescent-shaped outline; valves inflated
posteriorly and narrowed anteriorly. Valves thin and
translucent, but not excessively fragile; color gray exter-
nally where not covered with thin, light-yellow periostra-
cum; internally valves smooth, porcelaneous, and shining.
External surface smooth. Radial sculpture of fine threads
originating at umbos and radiating anteriorly, posteriorly,
and ventrally to shell margins. Threads visible from in-
ternal surface by transmitted light. Concentric sculpture
consisting of well-marked lines of growth accentuated by
areas of crowding which outline transition in shell shape
from only moderately to strongly inequilateral. Dorsal
margin broadly convex in mature individuals; ventral
margin markedly concave. Distance from umbos to pos-
terior margin exceeds distance from umbos to anterior
margin. Shell posteriorly hypertrophied, possibly for
brooding. Hinge teeth consist of single small, protruding,
peg-like cardinal in each valve which interdigitates with
its counterpart just anterior to internal opisthodetic liga-
ment that helps join valves. Dorsal margin thickened for

considerable distance both anterior and posterior to um-
bos. Umbos directed antero-medially. Pallial line not ev-
ident. Anterior adductor muscle scar hardly visible, long
and narrow as interpreted from animal’s anterior muscle;
posterior adductor muscle scar less elongate than anterior
scar. Prodissoconch small (about 30 wm in length) fan-
shaped, shining.

Animal with thickened mantle edge; mantle open an-
tero-ventrally forming incurrent-pedal aperture area.
Well-marked excurrent aperture located posteriorly.
Mantle open from ventral border of excurrent aperture to
region of lower border of anterior adductor muscle scar.
Ctenidium consists of only single demibranch, probably
the inner, but there appear to be both inner and outer
labial palps. Foot small, with well-marked byssal groove.

Holotype: USNM 836636; from R/V Anton Bruun SEP-
BOP Cruise 18B, Station 764; Lat. 4°06'S; Long. 81°
09'W; off NW Peru; 90 m; 8 September 1966; length 10.7
mm; height 6.6 mm.

Paratypes: 51 paratypes USNM 836637; from same sta-
tion; ranging in length from 1 to 10.9 mm; height from
0.8 to 7.4 mm.

Other specimens: 4 specimens USNM 836638; from R/

Page 86
|
(Ni

\ SS ~ a

Figure 5

Detail showing anterior end of a Pseudopythina murts spec. nov.
protruding from between parapodia of Aphrodita japonica.

Clams in
worm 1
N Dil
Length (mm)
Range 1.0-10.7
M 2.20
SD 1.94
V 3415
Height (mm)
Range 0.8-6.4
M 1.50
SD LED
V 125
H/L
Range 0.60-0.80
M 0.71
SD 0.05
V 0.002

Clams in
worm 2

1.3-6.4
2.20
1.87
3.48

0.62-0.72
0.67
0.03
0.001

Clams in
worm 3

6

1.4-10.7
Sails)
3.39

11.48

1.0-6.9
2.13
2.14
4.56

0.65-0.79
0.72
0.04
0.002

The Veliger, Vol. 27, No. 1

V Anton Bruun SEPBOP Cruise 16, Station 625a; Lat.
4°57'S to 5°01'S; Long. 81°23’W; off NW Peru; 118-133
m; 2 June 1966; ranging in length from 2.6 to 5.1 mm;
height from 1.8 to 2.7 mm.

Etymology: muris—genitive singular of the feminine (or
masculine) Latin substantive noun mus (mouse), meaning
“of the mouse,” alluding to the presence of Pseudopythina
murts spec. nov. in the respiratory cavity of the seamouse
Aphrodita japonica Marenzeller, 1879.

Remarks: Pseudopythina muris spec. nov. was found in
the respiratory cavity of Aphrodita japonica at two R/V
Anton Bruun stations in 90-133 m, from off northwestern
Peru in June and September 1966. The fact that at least
52 bivalves were found in 7 worms from one of the stations
indicates that this probably is not an adventitious rela-
tionship, although the other bivalve living with Aphrodita
in the east Pacific, Pseudopythina rugifera, also inhabits a
crustacean. In some cases, commensal relationships may
be purely fortuitous and based on the availability of a
suitable substratum, which happens to be another animal.
In this case the clam appears to be at least partially adapt-
ed to the Aphrodita host. The first individuals noticed were
attached by byssal threads to the ventral surfaces of the
Aphrodita in the vicinity of the parapodia. Those discov-
ered within the respiratory chamber of the worms were
byssally attached to the surfaces of the worms’ elytra, and
on at least two occasions, mature Pseudopythina muris were
found with their anterior ends protruding from between
two parapodia outside a worm’s respiratory chamber

Table 1

Measurements of Pseudopythina muris spec. nov. from R/V Anton Bruun SEPBOP Cruises 16, Station 625a, and 18B,
Station 764 (N = number of individuals in sample; M = arithmetic mean; SD = standard deviation; V = variance; H/L =

Station 764

Clams in
worm 4

1.1-7.4
3.64
2.87
8.25

0.64-0.79
0.69
0.05
0.003

ratio of shell height to length produced by dividing height by length).

Summary
Clams in Clams in Clams in Station Station
worm 5 worm 6 worm 7 764 625a
5 5 4 52 4
1.6-10.7 DNA 1.8-4.8 1.0-10.9 2.6-5.1
3.88 2.44 3.45 3.03 BY)
3.44 0.42 E25 Dahil 0.89
11.81 0.18 1.55 7.69 0.79
1.0-6.6 1.4-2.1 1.3=2:4 0.8-7.4 1.8-2.7
2.36 1.58 1.93 1.99 2.18
2.14 0.27 0.42 1.76 0.33
4.57 0.74 0.18 3.08 0.11
0.39-0.72 0.62-0.67 0.49-0.72 0.39-0.80 0.53-0.69
0.62 0.65 0.60 0.68 0.59
0.12 0.02 0.10 0.07 0.06
0.141 0.0004 0.010 0.005 0.107

J. Rosewater, 1984

(Figure 5). It is assumed this situation would provide the
clam with a direct source of fresh seawater for feeding
and respiration while the clam’s posterior portion is well
protected inside the worm’s respiratory cavity.

Although the clams have not been sectioned to deter-
mine their sexuality, leptonaceans are known to be mon-
oecious, and this mode of reproduction certainly would be
advantageous to an animal that may be isolated in a worm’s
respiratory cavity. How clams travel between hosts is un-
known. Leptonaceans are known to walk, however, and
young may be drawn into a worm’s respiratory cavity
through its incurrent points. Frequently there is a range
of individuals present in a worm, from smallest to largest
sizes (Table 1). Usually there is only a single large indi-
vidual, but, in two cases, two large individuals were pres-
ent in a worm. The other clams present are mostly of
smaller sizes: 1-5.1 mm in length. It is strongly suspected
that these young are produced ovoviviparously via a brood
pouch occupying the hypertrophied, globose posterior ends
of the larger specimens (see Figure 1, showing X-rays
taken from different angles to reveal expanded nature of
shells). An example of the pattern of distribution of dif-
ferent sized clams in a worm is shown in the drawing
(Figure 6).

In the adult stage, Pseudopythina muris is easily distin-
guished from the other West Coast Pseudopythina due to
its exaggerated crescent shape and hypertrophied poste-
rior. The other species are oval to subrhomboidal in out-
line, although there is clear evidence of an embayment in
the ventral margin of P. rugifera (see discussion under
Pseudopythina). Pythinella sublaevis (CARPENTER, 1857:
112) frequently has shell curvature, but it differs from
Pseudopythina in hinge morphology and is unrelated.

The unusual shape of Pseudopythina muris may be an
adaptation to life in the respiratory cavity of Aphrodita.
The oddly shaped shells of other Leptonacea provide evi-
dence of functional adaptations. Curvemysella paula lives
in association with a hermit crab (HABE, 1959). Similarly,
bivalves such as Rochefortia and Pythinella, with curved
ventral margins, nestle in apertures and boreholes of gas-
tropod shells where the curvature provides a secure pur-
chase (personal observations). The shell of Aligena cokeri
Dall, 1909, is grooved from near the umbos to its ventral
margin, reflecting a mid-ventral byssal attachment to the
tube of the Panamic polychaete Mesochaetopterus alipes
Monro, 1928 (also see MONRO, 1933, and ROSEWATER,
1976). When the mode of life of these and other aberrant-
looking bivalves is understood, there is often a functional
explanation for their peculiar appearances.

Further testimony to the major change in shape under-
gone during the maturation of Pseudopythina muris may
be noted in the table of measurements. There is an espe-
cially wide range in the ratio of height to length: 0.39-
0.80. This indicates the transition from rather elongate
young (0.39) to the mature individuals whose strong cres-
cent shape causes the more nearly 1:1 ratio of height to
length.

Page 87

7
Mo Na
A H h iN
Z ee eC ea
( j| ee aN
NaN

Figure 6

Various growth stages of Pseudopythina muris spec. nov. in situ,
attached to elytra of Aphrodita japonica (dorsal covering of res-
piratory cavity, or “burlap,” is cut away).

ABBREVIATIONS

The following institutional, program, and anatomical
abbreviations are used in this paper.

AM anterior adductor muscle
ANSP Academy of Natural Sciences of Philadelphia
CAS California Academy of Sciences

€0 excurrent opening

ff foot

h heart

ht hinge tooth

1 intestine

ia incurrent area

id inner demibranch

] ligament

li inner labia! palp

lo outer labial palp

MCZ Museum of Comparative Zoology, Harvard
University

me mantle edge

NMNH National Museum of Natural History, Smith-
sonian Institution
pm posterior adductor muscle

Page 88

SEPBOP South Eastern Pacific Biological Oceanograph-
ic Program

USNM _ United States National Museum (NMNH)

Vv visceral mass

ACKNOWLEDGMENTS

I am most grateful to G. Hendler and staff of the Smith-
sonian Oceanographic Sorting Center for bringing the bi-
valve-Aphrodita association to my attention, and to M. H.
Pettibone, NMNH, for identifying the worm and provid-
ing information on its anatomy and biology. K. J. Boss,
MCZ, E. Coan, Palo Alto, California, F. Bernard, Pacific
Biological Station, Nanaimo, B.C., Canada, W. T.
McGeachin, Louisville, Kentucky, and T. Gosliner, CAS,
gave helpful counsel. K. J. Boss, MCZ, and R. Robertson,
ANSP, graciously permitted me to examine collections
under their care. R. S. Houbrick and H. A. Rehder,
NMNH, gave advice of various kinds and criticized the
manuscript. P. Greenhall gave technical assistance and
Janine Higgins made the drawings.

Two anonymous reviewers made helpful recommen-
dations among which was the suggestion that I use the
superfamily name Galeommatacea in place of Leptona-
cea, based on date priority. The latter is not a current
requirement of the ICZN for names above family level,
nor do I consider it a productive procedure in groups such
as Leptonacea that are in a state of flux as concerns our
understanding of biological and nomenclatorial entities.
For those who wish to follow strict date priority to class
level in the Bivalvia, BERNARD (1983) includes a great
deal of useful and detailed information.

LITERATURE CITED

ABBoTT, R. T. 1974. American seashells. 2nd edition. Van
Nostrand Reinhold: New York. 663 pp.

ADAMS, A. 1856. Descriptions of thirty-four new species of
bivalve Mollusca (Leda, Nucula, and Pythina) from the
Cumingian Collection. Proc. Zool. Soc. Lond.:47-53.

BERNARD, F. R. 1983. Catalogue of the living Bivalvia of the
eastern Pacific Ocean: Bering Strait to Cape Horn. Cana-
dian Special Publication of Fisheries and Aquatic Sciences
61, Department of Fisheries and Oceans, Ottawa. vii + 102

PP-

Boss, K. J. 1965. Symbiotic erycinacean bivalves. Malacologia
3(2):183-195.

Boss, K. J. 1982. Mollusca Jn: S. P. Parker (ed.), Synopsis
and classification of living organisms. McGraw-Hill: New
York. 1:945-1166.

CARPENTER, P. P. 1857. Catalogue of the Reigen collection of
Mazatlan Mollusca in the British Museum. Warrington,
Oberlin Press. 552 pp.

CARPENTER, P. P. 1864. Supplementary report on the present
state of our knowledge with regard to the Mollusca of the
west coast of North America. Report of the British Associ-
ation for the Advancement of Science, for 1863:517-686.

CARPENTER, P. P. 1865. Diagnoses Specierum et Varietatum
Novarum Moluscorum, Prope Sinum Pugetianum a Ken-
nerlio Doctore, Nuper Decesso, Collectorum. Proc. Acad.
Natur. Sci. Philadelphia 17(2):54-64.

The: Veliger;, Volk 27-aiome

CHAVAN, A. 1969. Superfamily Leptonacea Jn: R. C. Moore
(ed.), Treatise on invertebrate paleontology. Part N, Vol-
ume 2(of 3), Mollusca 6, Bivalvia:N518-N537. Geological
Society of America, Inc. and University of Kansas.

ConTI, A. 1864. I] Monte Mario Ed I Suoi Fossili Subapen-
nini Raccolti E Paleontologo. Giovanni Cesaretti, Rome. 57

PP:

DaLL, W. H. 1899. Synopsis of the Recent and Tertiary Lep-
tonacea of North America and the West Indies. Proc. U.S.
Natl. Mus. 21:873-897, pls. 87-88.

Da.LL, W. H. 1900. Contributions to the Tertiary fauna of
Florida. Transactions of the Wagner Free Institute of Sci-
ence of Philadelphia 3(5):949-1218.

DaLL, W. H. 1909. Report on a collection of shells from Peru,
with a summary of the littoral marine Mollusca of the Pe-
ruvian zoological province. Proc. U.S. Natl. Mus. 37(1704):
147-294.

DaL_, W. H. 1916. Diagnoses of new species of marine bivalve
mollusks from the northwest coast of America in the collec-
tion of the United States National Museum. Proc. U.S. Natl.
Mus. 52:393-417.

Dance, P. 1966. Shell collecting, an illustrated history. Faber
and Faber: London. 344 pp., 35 pls.

DEsHAYES, G.-P. 1860. Descriptions des animaux sans ver-
tébres recouverts dans le Bassin de Paris 1(text):1-909, J.-
B. Bailliere: Paris.

DUNKER, W. 1864. Jn: A. E. Grube, Die Insel Lussin und
ihre Meersfauna. Breslau. vi + 116 pp., 1 pl., 1 map.
FISCHER, P. 1867. Description d’une nouvelle espece de Kellia

des Mers d’Europe. J. de Conchyl. 15:194-195, pl. 9, fig. 1.

FISCHER, P. 1878. Essai sur la distribution geographique des
brachiopodes et des mollusques du littoral oceanique de la
France. Actes Societe Linneenne Bordeaux (4)2:171-215.

FISCHER-PIETTE, E. 1950. Liste des types decrits dans la col-
lection de ce Journal. J. de Conchyl. 90(2):65-82.

Gass, W. B. 1873. On the topography and geology of Santo
Domingo. Trans. Amer. Philo. Soc. 15:49-259.

Gray, J. E. 1847. A list of the genera of Recent Mollusca,
their synonyma and types. Proc. Zool. Soc. Lond., Part XV:
129-219.

Hasse, T. 1959. Five new minute bivalves from Japan (Ery-
cinacea, Pelecypoda). Publ. Seto Mar. Biol. Lab. 7(2):291-
294.

Hasse, T. 1961. Four new bivalves from Japan. Venus 21(2):
150-156.

Hase, T. 1964. Shells of the western Pacific in color. Osaka.
2:vii + 233.

Hasse, T. 1977. Systematics of Mollusca in Japan. Bivalvia
and Scaphopoda. Tokyo. xiii + 372 pp.

JEFFREYS, J. G. 1881. On the Mollusca procured during the
Lightning and Porcupine Expeditions, 1868-70. Part 3. Proc.
Zool. Soc. Lond., for 1881, part 3:693-724, pl. 61.

JEFFREYS, J. G. 1882. On the Mollusca procured during the
Lightning and Porcupine Expeditions, 1868-70. Part 4. Proc.
Zool. Soc. Lond., for 1881, part 4:922-952.

Kuropa, T. & T. HaBe. 1971. Jn: T. Kuroda, T. Habe & K.
Oyama, The sea shells of Sagami Bay collected by His Maj-
esty the Emperor of Japan. Tokyo, pp. xix + 741 (in Jap-
anese), 489 (in English) Index 51 pp., 121 pls.

LaMaRCK, J. B. 1819. Histoire naturelle des animaux sans
vertébres 6(1):vi + 343.

Lamy, E. 1920. Revision des Cypricardiacea et des Isocardia
vivants du Museum d’Histoire Naturelle de Paris. J. de
Conchyl. 64:259-307.

LiscHKE, C. E. 1871. Diagnosen neuer Meeres-Conchylien
von Japan. Malakozoologische Blatter 18:39-45.

J. Rosewater, 1984

LocarbD, A. 1892. Les coquilles marines des cotes de France.

J.-B. Bailliere et Fils: Paris. 384 pp.

LocarpD, A. 1898. Mollusques testaces Jn: A. Milne Edwards,
Expeditions scientifiques du 7ravailleur et du Talisman pen-
dant les Annees 1880, 1881, 1882, 1883. 2:1-515, 28 pls.
Paris.

Monro, C. A. A. 1928. Papers from Dr. Th. Mortensen’s
Pacific Expedition 1914-1916. XLV. On the Polychaeta
collected by Dr. Th. Mortensen on the coast of Panama.
Videnskabelige Meddelelser Fra Dansk Naturhistorisk
Forening, Kjobenhavn 85:75-103.

Monro, C. A. A. 1933. The Polychaeta Sedentaria collected
by Dr. C. Crossland at Colon, in the Panamic region, and
the Galapagos Islands during the expedition of the S.Y. “St.
George.” Proc. Zool. Soc. Lond.:1039-1092.

NARCHI, W. 1969. On Pseudopythina rugifera (Carpenter, 1864)
(Bivalvia). Veliger 12(1):43-52.

NoRDSIECK, F. 1969. Die europaischen Meeresmuscheln (Bi-
valvia) Vom Ejismeer bis Kapverden, Mittelmeer und
Schwarzes Meer. Gustav Fischer Verlag: Stuttgart. xiii +
256 pp.

Page 89

OLproyp, I. S. 1924. The marine shells of the west coast of
North America. Stanford Univ. Publ., Univ. Ser., Geol. Sci.
1(1):1-247, 57 pls.

PAYRAUDEAU, B.-C. 1826. Catalogue descriptif et methodique
des mollusques de L’Ile de Corse. Paris. 218 pp.

PETTIBONE, M. H. 1953. Some scale-bearing polychaetes of
Puget Sound and adjacent waters. University of Washington
Press: Seattle. 89 pp.

Puiwipr!, R. A. 1836-1844. Enumeratio Molluscorum Siciliae.
Berlin. 1:xiv + 268 pp. (1836). Halle. 2:iv + 303 pp. (1844).

PONDER, W. F. 1965. The biology of the genus Arthritica.
Trans. Roy. Soc. New Zealand 6(8):75-86.

QuILes, A. M. 1973. Segnalazione di due molluschi nuovi per
il Mediterraneo. Conchiglie (Milano) 9(9-10):213-215.
ROSEWATER, J. 1976. Some results of the National Museum
of Natural History-Smithsonian Tropical Research Insti-
tute survey of Panama 1971-1975. Bull. Amer. Malacol.

Union, for 1975:48-50.

ROSEWATER, J. 1983. Another bivalve-Aphrodita association
with comments on adaptive significance of oddly shaped
Leptonacea. Amer. Malacol. Bull. 1:90-91.

The Veliger 27(1):90-92 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

Vitrea contracta (Westerlund) and Other Introduced

Land Mollusks in Lynnwood, Washington

BARRY ROTH

California Academy of Sciences, San Francisco, California 94118

TIMOTHY A. PEARCE

Department of Paleontology, University of California,
Berkeley, California 94720

Abstract. ‘The introduced land mollusk species Vitrea contracta (Westerlund, 1871), Cionella lubrica
(Miller, 1774), Oxychilus alliarius (Miller, 1822), Arion rufus (Linnaeus, 1758), Arion subfuscus (Dra-
parnaud, 1805), Limax maximus Linnaeus, 1758, and Deroceras reticulatum (Miller, 1774) occur in
Lynnwood, a suburb of Seattle, Washington. All are natives of Europe and introduced and dispersed
through human agency, probably including the use of leaves from other lots as mulch.

THE ONLY previous records of the European zonitid land
snail Vitrea (Crystallus) contracta (Westerlund, 1871) in
North America are from the San Francisco Bay area,
California (ROTH, 1977). There it was found in leaf litter
and on stems of ivy in landscaped or otherwise disturbed
areas of San Francisco, and in drift taken from around
Lake Merritt, Oakland.

In August 1983, we found Vitrea contracta in Lynn-
wood, a suburb of Seattle, Washington. The occurrence
is in two adjacent groves of red alders (Alnus rubra), each
about 10 x 10 m in dimension, planted as woodlots on
property between 44th Avenue W. to the east, 188th Street
S.W. to the south, 46th Avenue W. on the west, and an
unnamed driveway to the north (SE% NE™% sec. 16, T.
27 N, R. 4 E, Willamette Base and Meridian; USGS
Edmonds East Quadrangle [7.5-minute series, topograph-
ic], ed. 1953, photorev. 1981).

The ground is well drained and carpeted by a loose
cover of creeping buttercup (Ranunculus repens). At this
time of the year few other herbs were apparent. Under
the buttercup was about 2-4 cm depth of leafmold, con-
sisting mainly of leaves of the alders and bigleaf maple
(Acer macrophyllum) from a large tree growing within a
few meters of the alder groves.

According to the owners, the alders were planted in
1978. They were brought in as first- or second-year seed-
lings, purchased from a nursery in Bothell, Washington.
The groves and adjoining grounds have been mulched since

1975 with cow manure from a dairy in Bothell and with
leaves and grass clippings from parks and other properties
within a 24-km radius, some areas as far away as Seattle.
Before its use as a woodlot, the area now occupied by the
groves was used to grow strawberries. The carrying in of
leaves for mulch provides an obvious avenue of introduc-
tion for litter-dwelling mollusks.

Both living snails and empty shells of Vitrea contracta
were moderately common. The largest specimen found is
an empty shell 2.35 mm in diameter with 4.4 whorls. The
smallest, a live-collected individual, is 0.66 mm in diam-
eter with 2.0 whorls.

In the Old World, Vitrea contracta is widespread in the
British Isles as far north as the Outer Hebrides and ex-
tends throughout France, Germany, and the Low Coun-
tries. It occurs in Iceland but is absent from much of
central and northern Scandinavia (ROTH, 1977; KERNEY
& CAMERON, 1979). In the U.S.S.R. it occurs in the Baltic
region, the Vitebsk region, and the western regions of the
Ukraine (LIKHAREV & RAMMEL’MEIER, 1952). FORCART
(1973) reported it from Palestine. KUIPER (1964) and
EVANS (1972) have published habitat notes.

Other introduced land mollusks associated with Vitrea
contracta at this site are Cionella lubrica (Miller, 1774),
Oxychilus alliarius (Miller, 1822), Arion rufus (Linnaeus,
1758), and Arion subfuscus (Draparnaud, 1805). The first
two species are common at the site. Arion rufus and A.
subfuscus are not common in the alder groves but are more

B. Roth & T. A. Pearce, 1984

numerous around flower pots, wood on the ground, and
stacked construction blocks nearby. Deroceras reticulatum
(Muller, 1774) was not found in the groves but occurs
within 20 m, under potted plants. Limax maximus Lin-
naeus, 1758, was not found at the site in August 1983 but
was collected earlier, in July 1980. In November 1979 it
was found in a greenhouse on the same property.

Cionella lubrica has not been reported previously from
the Puget Sound valley. The only other Washington rec-
ord is from Walla Walla (PILsBRY, 1948). This Holarctic
species occurs naturally in North America, as shown by
its presence in deposits of Yarmouthian age in the Great
Plains (LEONARD, 1950). However, it is decidedly syn-
anthropic, and its occurrences in settled areas such as the
suburbs of Seattle likely involve transport by humans.

The American distribution of Oxychilus alliarius is very
incompletely known, partly because of the difficulty some
authors have had distinguishing among the several intro-
duced species of Oxychilus (cf. HANNA, 1966). Records
from Victoria, British Columbia (LA ROCQUE, 1953), and
Newport, Oregon (HANNA, 1966), place O. alliarius in the
Pacific Northwest, but it has not been reported previously
from the Seattle area. KOZLOFF (1976) indicated that O.
alliarius is the most common Oxychilus in backyards in the
Pacific Northwest, but did not cite specific localities. Its
native range includes northern and western Europe and
Iceland (KERNEY & CAMERON, 1979). The present spec-
imens were identified while alive by their garlic-like aro-
ma and by comparison of the shells with the excellent
diagnosis and illustrations of KERNEY & CAMERON (1979).

Arion rufus was identified by comparing the reproduc-
tive system with the figures and diagnoses of CAIN &
WILLIAMSON (1959), Quick (1947, 1960), and KERNEY
& CAMERON (1979). Diagnostic features include the large,
bulky, upper atrium and a vas deferens 1.5-2 times as
long as the epiphallus. Arion ater (Linnaeus, 1758) and
A. rufus are regarded by some authors as separate species
(Quick, 1947; WALDEN, 1976) and by others as subspe-
cies (CAIN & WILLIAMSON, 1959; Quick, 1960; ROLLO &
WELLINGTON, 1975; KERNEY & CAMERON, 1979). CAIN
& WILLIAMSON (1959), although presenting evidence that
the relationship is subspecific, regarded the taxonomic sta-
tus as unsettled (p. 82). WALDEN (1976) remarked that
the evidence was not conclusive; we follow him in treating
A. rufus as a species. We believe that more restrictive cri-
teria must be met to recognize a subspecies than a species;
therefore, when the evidence is inconclusive, the conser-
vative approach is to treat the taxon in question as a
species.

R. T. Paine (reported by GeTz & CHICHESTER, 1971)
believed A. ater to be restricted to more rural areas in the
Pacific Northwest, while A. rufus was more or less con-
fined to cities. The criteria he used to recognize the two
taxa were not specified. ROLLO & WELLINGTON (1975)
summarized the history of accounts of “Avion ater” (in-
cluding A. rufus) in the Pacific Northwest. They reported
that dissected specimens from the vicinity of Vancouver

Page 91

had genitalia more like rufus than ater as described by
Quick (1947) and noted that a figure of an Oregon spec-
imen by PILsBRY (1948) also appeared to be rufus.

Arion subfuscus has been reported from the Pacific
Northwest previously by GETZ & CHICHESTER (1971) and
ROLLO & WELLINGTON (1975). In the vicinity of Van-
couver, British Columbia, A. swbfuscus occurs in both cul-
tivated areas and natural woodland, probably becoming
introduced to the woods when gardeners dumped garden
refuse and compost in such areas (ROLLO & WEL-
LINGTON, 1975). The native range of A. subfuscus includes
most of Europe (LIKHAREV & RAMMEL’MEIER, 1952;
KERNEY & CAMERON, 1979); it has also been introduced
into northeastern North America (PILSBRY, 1948; CHICH-
ESTER & GETZ, 1969). To our knowledge, this is the first
report of the species from the Puget Sound valley. The
present specimens were identified by dissection. According
to WALDEN (1976:25), “A. subfuscus shows a complicated
subspecific taxonomy. It is not excluded that further re-
search will show that an aggregate species is involved.”

Limax maximus has long been known as an introduction
in the Pacific Northwest (PILSBRY, 1948; HANNA, 1966;
GETZ & CHICHESTER, 1971; ROLLO & WELLINGTON,
1975). HANNA (1966) summarized several reports of De-
roceras reticulatum in western Washington from the pest-
control literature. ROLLO & WELLINGTON (1975) found
it the most abundant species in British Columbia. Both
L. maximus and D. reticulatum are widespread in temper-
ate Europe and introduced by commerce to North Amer-
ica and elsewhere.

Voucher specimens of these species are on deposit in
the California Academy of Sciences. We gratefully ac-
knowledge the support and forbearance of Mr. and Mrs.
C. K. Pearce, Jr. of Lynnwood.

LITERATURE CITED

Cain, A. J. & M. H. WILLIAMSON. 1959. Variation and spe-
cific limits in the Avion ater aggregate. Proc. Malacol. Soc.
Lond. 33(2):72-86.

CHICHESTER, L. F. & L. L. Getz. 1969. The zoogeography
and ecology of arionid and limacid slugs introduced into
northeastern North America. Malacologia 7(2-3):313-346.

Evans, J. G. 1972. Land snails in archaeology, with special
reference to the British Isles. Seminar Press: London &
New York. 436 pp.

ForcartT, L. 1973. Vitrea contracta (Westerlund, 1873) (Zoni-
tidae, Vitreinae) in Palestine. Argamon, Israel J. Malacol.
4(1):7-8.

Getz, L. L. & L. F. CHICHESTER. 1971. Introduced European
slugs. Biologist 53(3):118-127.

Hanna, G D. 1966. Introduced mollusks of western North
America. Occas. Pap. Calif. Acad. Sci., No. 48. 108 pp.
KErRNEY, M. P. & R. A. D. CAMERON. 1979. A field guide to
the land snails of Britain and north-west Europe. William

Collins Sons: London. 288 pp.

Koz.orr, E. N. 1976. Plants and animals of the Pacific North-

west. Univ. of Washington Press: Seattle & London. 264

Pp.
Kuiper, J. G. J. 1964. On Vitrea contracta (Westerlund). J.
Conchol. 25(7):276-278.

Page 92

The Veliger, Vol. 27, No. 1

La Rocqugr, A. 1953. Catalogue of the Recent Mollusca of
Canada. Natl. Mus. Canada Bull., No. 129. ix + 406 pp.

LEONARD, A. B. 1950. A Yarmouthian molluscan fauna in the
midcontinent region of the United States. Univ. Kansas Pa-
leontol. Contrib., Mollusca, Art. 3. 48 pp.

LIKHAREV, I. M. & E. S. RAMMEL’MEIER. 1952. Nazemnye
molyusski fauny SSSR [Terrestrial mollusks of the fauna of
the U.S.S.R.]. Akad. Nauk SSSR Zool. Inst., Moscow &
Leningrad. English transl. by Israel Progr. Scientif. Transl.,
Jerusalem 1962. 574 pp.

Pitssry, H. A. 1948. Land Mollusca of North America (north
of Mexico). Monogr. 3, Acad. Natur. Sci. Philadelphia 2(2):
i-xlviii, 521-1113.

Quick, H. E. 1947. Arion ater (L.) and A. rufus (L.) in Britain
and their specific differences. J. Conchol. 22(10):249-261.

Quick, H. E. 1960. British slugs (Pulmonata: Testacellidae,
Arionidae, Limacidae). Bull. British Mus. (Nat. Hist.), Zool.
6(3):103-226.

ROLLo, C. D. & W. G. WELLINGTON. 1975. Terrestrial slugs
in the vicinity of Vancouver, British Columbia. Nautilus
89(4):107-115.

Rotu, B. 1977. Vitrea contracta (Westerlund) (Mollusca: Pul-
monata) in the San Francisco Bay area. Veliger 19(4):429-
430.

WALDEN, H. W. 1976. Nomenclatural list of the land Mol-
lusca of the British Isles. J. Conchol. 29(1):21-25.

The Veliger 27(1):93-96 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

Determining the Area of a Gastropod’s Foot!

RONALD V. DIMOCK, Jr.

Department of Biology, Wake Forest University,
Winston-Salem, North Carolina 27109

Abstract. A photographic procedure involving the weighing of enlarged images of the foot of the
prosobranch Jlyanassa obsoleta has been applied to the problem of determining the area of a gastropod’s
foot. The results have been compared with those derived from a microcomputer-assisted video scanning
procedure and with estimates of pedal area employing conventional elliptical and rectangular geometric
models of foot shape. Significant differences in the quantitative predictions of regression models of pedal
area as a function of snail size occurred among the six techniques used to determine pedal morphometry.
The photography-weighing technique was highly reliable and compared favorably with video scanning.
The geometric models over- or underestimated pedal surface area differentially as a function of both
the size of a snail and the selection of a width parameter for the calculation of geometric area.

INTRODUCTION

For non-pelagic motile gastropods the ventral surface of
the foot is important not only for locomotion but also for
the maintenance of position against the effects of gravity,
wind and waves. A comprehensive understanding of gas-
tropod pedal morphology and locomotory mechanisms
might include a description of locomotory types (MILLER,
1974a), an analysis of adaptive and functional attributes
(MILLER, 1974b; GAINEY, 1976; LINSLEY, 1978; PALMER,
1980), and knowledge of behavioral aspects of locomotion
(BRETZ & DimMock, 1983; DiMock, in press). In such
studies it is often important to have an estimate of quan-
titative parameters of pedal morphology. However, the
measurement of fleshy, mucus-secreting morphological
features of a motile soft-bodied organism may not always
be readily effected.

In this paper I present a photographic approach to
quantifying morphometric parameters of the foot of the
marine mud snail J/yanassa obsoleta (Say, 1822). The data
from this technique are compared with those derived from
a microcomputer-based video image analyzer, as well as
calculations of conventional geometric models of pedal
surface area. The photographic procedure is shown to be
highly reliable. It is readily adaptable to conditions (or
species?) under which standard geometric models may yield
grossly inaccurate estimates of pedal morphometry.

MATERIALS ann METHODS

All specimens of J/yanassa obsoleta were collected from the
Newport River marshes near Morehead City, North Car-

‘ Contribution No. 204 from the Tallahassee, Sopchoppy and
Gulf Coast Marine Biological Association.

olina. The foot of each of 20 animals (shell length = 9.1-
18.3 mm) was photographed as a snail crawled vertically
up the side of a glass aquarium. Several exposures were
made of each animal and also of lined graph paper (5 mm
squares) held against the inside of the same wall of the
aquarium. All of the exposures were taken at the same
distance from the aquarium with a 35-mm camera with
close-up lenses. The exposure in which a snail’s foot ap-
peared most nearly bilaterally symmetrical was selected
for printing.

Three prints of each snail’s foot and seven of the graph
paper were enlarged (about 6 x) and processed identically
with an automatic print processor. After the prints were
dried, each image of a snail’s foot was carefully cut from
the photographs and weighed to 0.1 mg. The area of the
pedal surface was estimated by comparison to the mean
weight of a standard “1 cm?’ as determined from the
prints of the graph paper. The dimensions of a snail’s foot
were determined by reference to the grid system of the
photographs of the graph paper, with foot width being
measured both as the maximum width, exclusive of the
antero-lateral horns of the propodium, and the width at
one-half foot length.

Each cutout image of a snail’s foot was also scanned
with a microcomputer-based video image analyzer (Dar-
win Instrument Company, Winston-Salem, NC) which
utilizes an analytical video camera with appropriate dig-
itizer to computer interface and associated software to re-
solve such parameters as the length, width, or area of an
image (TELEWSKI et al., 1983). The area of the foot was
also calculated as the area of an ellipse and of a rectangle
with the two measures of width described above.

The association of logarithm foot area with logarithm
shell length was assessed by Pearson’s product-moment

Page 94

The Veliger; Vol. 27-3 Nom

Table 1

The magnitude and accuracy of various estimates of the pedal area of J/yanassa obsoleta in reference to shell length (SL),
foot length (FL), and foot width (FW) expressed both as maximum width (A) and width at one-half FL (B).

Estimated area (mm?)

FW (mm) By By By ellipse

(mm) (mm) A B weight video A B

9.1 UB 3.62 =. Si 20.1 20.0 20.6 17.8
10.2 TO --410. 33:3 2371 23.0 24.8 20.5
10.2 8.4 4.1 3.6 26.5 Poe GPATAD = P2Shas)
10.9 956. 5.37 4:8: 40.6 40.8 40.0 36.2
11.0 84 44 3.8 Dio 20.8) 29 Oe 255
1250 VO%Si 5:0) 3 7423 40.8 40.1 40.5 34.8
13:5: WS) 6x1 6.0 58.1 59.4 55.1 54.2
14:2 07 1221 6:2), 5:6 ee) 57.8 58.9 53:2
TANS IQ FON Toa poe 60.0 60.2 57.8 Soa,
14255) 12 See 1525) (3 25.0 54.9 54.4 54.0 49.1
Pel I2SS ie G2" 526 61.7 6273) 56233 56.3
1522S Oe O88 Piles, “ass — Olt Gav!
16357 121955 Orde Ou 67.3 68.8 65.9 61.8
16.4 129 69 6.8 73.4 74.1 69.9 68.9
16.7 13.1 HA HS 80.1 81.9 76.1 Usil
16:8. 15:5 6x7) (6:2 8477, 383.3) 8106) = 75:5
W723 NG:0) 7671629 Oya ae} WES) 86.7
17.3. 14:0 _. 7A 6.7 81.5 80.4 78.1 eet
17.6 16.1 7.0 6.4 88.4 88.2 88.5 80.9
18:35 153) 7298 ee 96.5 96.4 94.9 88.9

correlation for each of the six measures of foot area. The
slopes and elevations of the resulting regression equations
were compared by analysis of covariance (ANOCOVA);
significant differences among the regressions were re-
solved with Student-Newman-Keuls multiple range test
(SNK; Zar, 1974).

RESULTS

All weights of a standard cm’ of the enlarged photographic
prints were within 1.8% of the mean (n = 7); no print of
a snail’s foot varied more than 2.0% from the mean weight
(n = 3) for that animal.

The morphometric data for 20 specimens of J/yanassa
obsoleta are presented in Table 1. The video scan proce-
dure and the weighing technique were virtually identi-
cally precise for determining the area of the image of a
snail’s foot. However, the elliptical and rectangular models
consistently over- or underestimated the area of pedal sur-
face relative to the weighing technique (Table 1). When
the area of the foot was modeled as an ellipse, both the
sign and the magnitude of the error in estimating pedal
area were influenced by the way the width of the foot had
been determined.

There was no consistent pattern of the error of esti-
mating pedal area with the elliptical model when the area
was calculated using the maximum width. However, when

Difference (as % of “by weight’’)

By rectangle Ellipse Rectangle

B Video A B A B
26.3 22.6 Oey eas) lil At +30.8 +12.4
31-6) 9 2651 =O Sth 1181.5) 13333 st allO
34.4 30.2 xo) ae) 07 +29.8 +14.0
50.9 46.1 +0.5 hs) —10.8 +25.4 sri 3)o9)
37.0 31.9 ES) Wek {351 ODED +16.8
51.5 44.3 A. 0.7 14.7 +26.2 +8.6
70.2 69.0 Paya. =) =O) +20.8 +18.8
75.0 67.8 AN arial {ee TAD) +17.1
Tees, Oia! Oe). Bei Allee +22.5 +11.8
68.8 62.5 SO 1G 10,6 st 2OES +13.8
US Alo +O uO —8.8 +28.7 +16.2
S653) 7/985 aPdkde) 3B ier +20.7 spill
83.9 78.7 ty. =D, =) +24.7 +16.9
89.0 87.7 stele Opin G —6.1 = 2iles) tr D5)
96.9 95.6 Rays) —=5)40) =6.2 +21.0 +19.4
103.9 96.1 I =a" = 109 OM aPilé),5)
121.6 110.4 +0.1 +0.3 = 819 ar allol! +16.0
99:4 9358 =O Wea 422 —9.6 +22.0 tallest
112.7 103.0 Sri 2 act OF =8'5 +25 +16.5
120198 113° AS it = 7/9) toes atalied
Xe =O poole =9,f +26.0 +149

the width was taken as that at one-half of foot length, the
error varied with the size of the snail; the coincidence of
the elliptical model of pedal area with the area determined
by the weighing technique was positively correlated with
shell length (7 = 0.449, df = 18, P = 0.047). Thus, the
area of the foot of a small specimen of Jlyanassa obsoleta
was less accurately modeled by an ellipse when foot width
was measured at one-half foot length (Table 1), but the
precision of the elliptical model increased with increasing
snail size.

The rectangular geometric model overestimated pedal
area by as much as 35% (Table 1). In contrast to the
elliptical model, the greatest deviation between the area
calculated with the rectangular model and that determined
by weighing occurred when the width of the foot was
taken as the maximum width (Table 1). The magnitude
of that overestimation was negatively correlated with snail
size (r = —0.590, df = 18, P = 0.006). However, when the
width at one-half foot length was used to calculate rect-
angular area, the error of overestimation was positively
correlated with shell length (r = 0.478, df = 18, P = 0.033;
Table 1). Thus, both the magnitude and the size-specific
characteristics of the error in estimating pedal area were
functions of the parameters used in the geometric models.

Although both the length and the width (and conse-
quently the area) of the foot of //yanassa obsoleta increased

R. V. Dimock, Jr., 1984

Page 95

Table 2

The area (FA) of the foot of J/yanassa obsoleta as a function of shell length (SL): a comparison of techniques.

Procedure for

determining area Regression equation Te df P
Weighing *log FA = 2.23 log SL — 0.83 0.956 18 <0.001
Video *log FA = 2.27 log SL — 0.86 0.953 18 <0.001
Ellipse (A) (maximum

foot width) *log FA = 2.14 log SL — 0.72 0.963 18 <0.001
Ellipse (B) (foot width

at ¥2 foot length) log FA = 2.29 log SL — 0.94 0.957 18 <0.001
Rectangle (A) (maximum

foot width) log FA = 2.14 log SL — 0.61 0.963 18 <0.001
Rectangle (B) (foot width

at % foot length) *log FA = 2.29 log SL — 0.83 0.957 18 <0.001
ANOCOVA:

H.: Slopes of regression equations are equal F = 0.39 df = 5,108 P = 0.428

H,: Elevations of regressions are equal F = 28.1 df = 5,108 P < 0.001

* Indicates regressions that are not significantly different (SNK; P > 0.05)

with increasing shell length (Table 1), the apparent quan-
titative association of pedal area with shell length varied
with the technique employed in estimating that area (Ta-
ble 2).

DISCUSSION

Although a quantitative assessment of foot morphometry
may be central to an understanding of some aspects of the
biology of gastropods, the techniques for determining such
parameters as area of the pedal surface may either simply
not be identified (GAINEY, 1976) or may be only incom-
pletely described (MILLER, 1974b). For example, in one
of the more thorough analyses of the adaptive design of
prosobranch pedal morphology, MILLER (1974b) simply
states that the length and width of a snail’s foot “‘were
measured” and that area of the foot was calculated as the
area of a rectangle or of an ellipse “depending upon the
shape of the foot.” No information is provided as to how
the linear dimensions of a snail’s foot actually were phys-
ically determined nor upon what basis a decision was made
about which model of the shape of a gastropod’s foot was
most appropriate for determining the pedal area of a given
snail (MILLER, 1974b). These parameters were then used
by Miller to characterize the pedal morphometry of an
array of species and to relate these morphometric attri-
butes to functional and adaptive parameters of foot form.

It is clear from the present study that not all techniques
for the determination of pedal morphometry yield equally
reliable estimates of the quantitative properties of gastro-
pod feet. Aside from difficulty in the mechanics of mea-
suring linear features of a motile, fleshy structure, there
may also be significant consequences of the selection of a
geometric model for estimating an important parameter

such as area of the foot. If one assumes that the photog-
raphy-weighing procedure yielded a good measure of foot
morphometry, then the alternative geometric models for
determining pedal surface area can be compared. One
obvious conclusion is that a rectangular model of pedal
surface is not a very accurate depiction of the morphology
of the foot of Jlyanassa obsoleta. For all sizes of snails
examined, the rectangular model overestimated pedal area
(Table 1). The closest correspondence between the rect-
angular model and the shape of the foot of J. obsoleta
occurred among the smaller snails when the rectangular
dimensions were based upon width of the foot as measured
at one-half foot length. However, even under those con-
ditions the rectangular model overestimated pedal surface
area by more than 10% (Table 1).

Overall, an elliptical model provided a reasonably good
estimate of pedal surface area for Ilyanassa obsoleta, but
only when the width of the foot was taken as the maxi-
mum width (Table 1). When the width was considered
as that at one-half foot length [which was Miller’s ap-
proach (MILLER, 1974b)], the elliptical model underesti-
mated pedal area. The extent of underestimation was
greatest among the smaller snails (Table 1), an observa-
tion that is consistent with the better relative fit of the
rectangular model to the same animals. Thus, although
the ratio of foot length to maximum foot width is constant
over a range of shell lengths for J. obsoleta (DIMOCK, in
press), the shape of this snail’s foot does change with the
size of the animal. Therefore, one would be in error to
assume that a single geometric model adequately describes
the morphology of this mud snail’s foot irrespective of
shell size. It is likely that similar size-specific morpho-
metric relationships exist among other species of gastro-
pods.

Page 96

An analysis of the various regressions of the area of the
foot of Ilyanassa obsoleta on shell length confirms the sup-
position that certain techniques are more satisfactory than
others for quantifying pedal morphology (Table 2). Al-
though each procedure for estimating area employed in
this study would reveal that the area of this snail’s foot is
a positive function of shell length, the precise quantitative
characteristics of that association depend upon how spe-
cific morphological parameters are determined. Such
quantitative relationships are influenced not only by the
selection of a particular geometric model of foot mor-
phology, but also by the way in which a linear dimension
may be defined. The use of a procedure such as the pho-
tography-weighing technique has the added advantage of
obviating any subjective evaluation of whether or not one
geometric model is more appropriate than another (MIL-
LER, 1974b).

The weighing of photographic images of snail feet and
the microcomputer assisted video camera scanning of the
same images yielded quite comparable measures of the
original surface area of the foot of Jlyanassa obsoleta.
Clearly, the photography-weighing procedure is adapta-
ble to numerous laboratory contexts and requires much
less sophisticated equipment than does the video scanning
system. This photo-morphometric procedure should be
useful in an assortment of investigations of various aspects
of the biology of gastropods.

The Veligers, Vola Zia hom

ACKNOWLEDGMENTS

I appreciate the assistance of Dr. Frank Telewski with
the video camera scanning procedure. This study was sup-
ported by a grant from the Wake Forest University Re-
search and Publication Fund.

LITERATURE CITED

Bretz, D. D. & R. V. Dimock, JR. 1983. Behaviorally im-
portant characteristics of the mucous trail of the marine
gastropod Ilyanassa obsoleta (Say). J. Exp. Mar. Biol. Ecol.
71:181-191.

Dimock, R. V., JR. In press. Quantitative aspects of locomo-
tion by the mud snail J/yanassa obsoleta. Malacologia.

GaINnEY, L. F., JR. 1976. Locomotion in the Gastropoda: func-
tional morphology of the foot in Neritina reclivata and Thais
rustica. Malacologia 15:411-431.

LINSLEY, R. M. 1978. Locomotion rates and shell form in the
Gastropoda. Malacologia 17:193-206.

MILLER, S. L. 1974a. The classification, taxonomic distribu-
tion, and evolution of locomotor types among prosobranch
gastropods. Proc. Malacol. Soc. Lond. 41:233-272.

MILLER, S. L. 1974b. Adaptive design of locomotion and foot
form in prosobranch gastropods. J. Exp. Mar. Biol. Ecol.
14:99-156.

PALMER, A. R. 1980. Locomotion rates and shell form in the
Gastropoda: a re-evaluation. Malacologia 19:289-296.
TELEWSKI, F. W., A. H. WAKEFIELD & M. J. JAFFE. 1983.
Computer assisted image analysis of tissues of ethrel treated

Pinus taeda seedlings. Plant Physiol. 72:177-181.

ZAR, J. H. 1974. Biostatistical analysis. Prentice-Hall, Inc.:

Englewood Cliffs, New Jersey. 620 pp.

The Veliger 27(1):97-98 (July 2, 1984)

THE VELIGER
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The Western Society of Malacologists Meeting
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The Veliger 27(1):99 (July 2, 1984)

THE VELIGER
© CMS, Inc., 1984

S. Stillman Berry, 1887-1984

Samuel Stillman Berry, Honorary Life President of
the American Malacological Union, passed away on
April 9, 1984, at the age of 97.

Berry was born in Unity, Maine, on March 16, 1887.
Remaining in his very considerable collection of mol-
lusks is the first shell he picked up at Point Judith,
Rhode Island, in 1893. His family lived for short pe-
riods in New York City, Phoenix, and Montana, seek-
ing a climate suitable for his frail health. In 1897 they
finally settled in Redlands, California, which he called
his home ever since, spending part of his summers at
the family’s Montana ranch.

After high school in Redlands, he did undergraduate
work at Stanford University (1905-1909), received his
Master’s Degree at Harvard University in 1910, and
returned to Stanford for his PhD, which he received in
1913. His thesis was on the Cephalopoda.

In 1913 he went to work at Scripps Institution of
Oceanography where he helped to build their library
and, as a consequence, his own collection of natural
history books, perhaps the finest remaining in private
hands.

He was supported chiefly by his family’s 55,000-acre
Winnecook Ranch in Montana, of which he was Chief
Executive Officer for over 65 years, a record in cor-
porate America. He was thus able to pursue indepen-

dent work in malacology, authoring, from 1906 on-
ward, over 165 papers and an equivalent number of
new species. Some 28 genera and species are named in
his honor. In addition to his papers on cephalopods, he
is particularly noted for his work on chitons and land
snails. In later years, he concentrated on the Panamic
marine fauna, publishing much of his work in his own
Leaflets in Malacology. He was also a horticulturist of
note, considered an expert on irises and daffodils.

Berry could hold the rapt attention of visitors to his
somewhat cluttered Redlands home with lucid stories
about his experiences in the San Francisco Earthquake,
other adventures, specimens in his collection, books in
his library, and the famous naturalists he met during
his career, including G. B. Sowerby, III, Robert E. C.
Stearns, Addison E. Verrill, Charles T. Simpson, the
Rev. Joseph Rowell, and Edward S. Morse. He had
an outstanding memory for the details of events long
past.

He had very sharp powers of observation, noting
morphological features that others had missed. His ex-
tensive collection is meticulously numbered and _ la-
beled, many lots having slips with extensive, neatly
printed notes and comments.

Eugene Coan

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a) Periodicals
Cate, J. M. 1962. On the identifications of five Pacific Mitra. Veliger 4:132-134.

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288 pp.

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CONTENTS — Continued

Notes on the tergipedid nudibranchs of the northeastern Pacific, with a descrip-
tion of a new species.
DAvap; W.. BEHRENS 9 2)00:5. od)..4s ah tailed eee tee ese ee 65

The morphology, reproduction, and ecology of the commensal bivalve Scintillona
bellerophon spec. nov. (Galeommatacea).
DIARMAID. O’ FOIGHIL AND: ALLAN GIBSON) 7.22). 50.) 0, ee 72

A new species of leptonacean bivalve from off northwestern Peru. (Heterodonta:
Veneroida: Lasaeidae).
JOSEPH “ROSEWATER (8.0. 15508 Uo Bia aha MAUD PR fe eh ern ces et een 81

Vitrea contracta (Westerlund) and other introduced land mollusks in Lynnwood,
Washington.
BARRY ROTH: AND TIMOTHY A: PEARCE. 25-0 Ge.) eee eee 90

Determining the area of a gastropod’s foot.
RONALD: V.. DIMOCK,JRe iy )c0 e Meies = ee 8d es I eee 93

NOTES, INFORMATION & NEWS

ISSN 0042-3211

THE

A Quarterly published by

CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC.
Berkeley, California

R. Stohler, Founding Editor

Volume 27 October 5, 1984 Number 2

CONTENTS

Culture of the California red abalone Haliotis rufescens Swainson (1822) in
Chile.
Buzz Owen, Louis H. DiSALvo, EARL E. EBERT, AND ERIKA FONCK .... 101

Multivariate analysis of geographic variation in Cypraea caputserpentis (Gastro-
poda: Cypraeidae).
| SURUUAING IN| 7S OFS cp varer8 Jen ee Ue oN Nea esate an Se ERR Co es re 106

Seasonal variation in biochemical composition of the fresh-water pond snail
Vieiparus bengalensis Linnaeus.

BAK GUPRAGCANID ON er S a IDWIRVIB eves ene cel oo a ous eG a eile i et 120

Gonadal organization and gametogenesis in the fresh-water mussel Diplodon
chilensis chilensis (Mollusca: Bivalvia).

SANTIAGO PEREDO AND ESPERANZA PARADA ............. 00000 0b eee 126

The effects of aerial exposure and desiccation on the oxygen consumption of
intertidal limpets.
ENTUANSTPATTIR fe LONGRISIS ae eartote eaes a ea Protea ee aN en A Be Cn A Corte cores TE 134

Predator deterrence by flexible shell extensions of the horse mussel Modiolus
moduolus.
MARY Me WRIGHT AND LISBETH FRANCIS ..-.....2....)0.......2.... 140

The opisthobranchs of Cape Arago, Oregon, with notes on their biology and a
summary of benthic opisthobranchs known from Oregon.
SJERPREVa eRe nGODDAR DY er citi cs dpeveni citeliietie toa) ae Weasel heey als W gale 143

CONTENTS — Continued

The Veliger (ISSN 0042-3211) is published quarterly on the first day of July, October,
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The Veliger 27(2):101-105 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

Culture of the California Red Abalone Halzotis rufescens
Swainson (1822) in Chile

BUZZ OWEN,' LOUIS H. DISALVO,?
EARL E. EBERT,’ anD ERIKA FONCK?

‘P.O. Box 601, Gualala, California 95445
* Department of Marine Research (DIMAR), University del Norte, Coquimbo, Chile
* California Department of Fish and Game, Marine Culture Laboratory,
Granite Canyon, Coast Route, Monterey, California 93940

Abstract. Haliotis rufescens has been experimentally cultured and maintained during hatchery re-
search in Coquimbo, Chile. Spontaneous spawnings in laboratory populations were observed in spring
months from 1979 to 1982, accompanying temperature changes of the ambient seawater. Spawning
was artificially induced at various times of the year without conditioning. Broods were produced from
both spontaneously occurring and induced spawnings. Once capable of feeding on macroalgae, abalone
were reared on the locally abundant Lessonia flavicans, although it was experimentally shown that
young juveniles grew best when presented with a mixed diet of macro- and microalgae.

INTRODUCTION

THE EXTENSIVE rocky Chilean sublittoral environment,
with its cool temperature and rather extensive macroalgae
assemblages appears to offer suitable habitat for the growth
of abalone, Haliotis spp. However, endemic haliotids are
unknown in Chile although many other coastlines of the
world with similar characteristics host several species of
this genus (Cox, 1962). The zoogeographical problem of
why no haliotids occur in Chile and the possibility of
introducing Haliotis spp. to Chile as a new marine re-
source have long interested both Chilean and U.S. re-
searchers. A one-year study, supported by the Organiza-
tion of American States (OAS), examined the feasibility
of bringing an abalone species from California to Chile
under quarantined test conditions (EBERT, 1980). In Sep-
tember 1979, about 300 adult and juvenile hatchery-reared
Halwotis rufescens were brought from California to Chile
by two of us (Owen and Ebert), and maintained at the
Department of Marine Research (DIMAR), University
del Norte, Coquimbo (29°59’S, 71°22'W). Laboratory and
field experiments were conducted to examine ecological
relationships between the red abalone and endemic Chil-
ean species. Inclusive were studies to determine predator-
prey relationships and adequacy of the macroalgae (ac-
ceptance, food conversion efficiency, and abalone growth
rates). Early in this study some abalone spawned spon-
taneously; the resulting larvae were reared under impro-

vised conditions. In this report, we document results of
this culture and of a later culture from a spawning in-
duced by the methods of KIKUCHI & UKI (1974). We also
include data on the comparative growth of small juveniles
raised on different diets of Chilean algae.

MATERIALS anpD METHODS

DIMAR is located on the northeast margin of Herradura
Bay, which is a semi-protected coastal embayment with
an oceanic salinity regime. The bay receives negligible
freshwater input and sources of contamination are mini-
mal. The temperature range at 10-m depth is typically
13-15°C (ALFSEN, 1979).

Spontaneous Spawning

Several adult abalone, 12 cm in length, which had been
in Chile for two weeks, spawned unexpectedly on 22 Sep-
tember 1979 within tanks of continuously renewed sea-
water at a temperature of 14.4°C. Seawater used as the
culture medium for these gametes, larvae, and juveniles
was obtained directly from an intake at 10-m depth on
the bay bottom. This water was filtered in the laboratory
using polypropylene filter bags (GAF Corp.) which re-
tained particles greater than 10 wm. About 3 million eggs
from one female were fertilized with about 10 mL of a
dense sperm suspension from two males, and the progress
of fertilization was monitored by microscopy. After one

Page 102

hour, fertilized eggs were rinsed to remove excess sperm
by three decantations following fresh seawater refills, and
were distributed evenly, as judged by sight, to one layer
on the plastic pail bottom. Each pail contained 10 L of
seawater at 12.5-13.5°C. The static seawater in these cul-
tures rose to air temperature of 17°C over 12 h. Upon
reaching the veliger stage, abalone larvae were gently
rinsed onto a 52-um mesh nylon screen (Nytex; Tetko,
Inc., Elmsford, New York), and distributed at several dif-
ferent densities into plastic containers of 10, 20, or 100-
L capacity. These culture containers were subject to am-
bient temperature fluctuations between 13 and 18°C. All
seawater was changed daily in the smaller cultures, and
one-third the volume was changed daily in the 100-L tanks.
Growth and development of larvae were observed daily
and mortality was estimated from the quantity of empty
shells recovered by screening during seawater changes.
Microalgae that settled and grew on container surfaces
provided forage. Newly settling larvae were given pure
cultures of Tetraselmis suecica, and as early growth of post-
larvae progressed, pennate diatoms (unidentified) har-
vested from aquarium surfaces in the laboratory were in-
troduced to the cultures as food.

At a mean size of approximately 5 mm, the abalone
juveniles were transferred to 1000-L rectangular fiber-
glass tanks which received a continuous flow of unfiltered
seawater from 10-m depth in the bay. At this time, pieces
of Lessonia flavicans, L. nigrescens, and Macrocystis integ-
rifolia were offered to the juvenile abalone, although feed-
ing with microalgae was continued until the young aba-
lone were fully capable of consuming the macroalgae.

Induced Spawning

Abalone were induced to spawn in April 1980 and a
controlled rearing experiment was carried out over 12
months. Fertilization and larval rearing were carried out
in a heated laboratory at 18-19°C. Seawater was pumped
to this laboratory through an offshore sand filter located
at 3-m depth on the bay floor. This water was filtered to
10 wm in the laboratory, and normally had a temperature
of 15°C. It was held without further treatment and, after
reaching the laboratory temperature of 18°C, was used for
the handling of gametes, larvae, and small juveniles.

Two male and two female abalone (6-8 cm in length)
that appeared ripe were transferred from holding tanks
and placed separately by sex into 20-L plastic pails. These
pails were supplied with running seawater at 14°C, fitted
with screens on top to prevent crawling out, and left over-
night. On the following morning, fecal material was
washed from the pails, and the abalone were given a sea-
water flow of 250 mL/min at 17°C via an ultraviolet
(UV) water treatment unit (REFCO Intl., Hayward, CA,
model RL-10). The seawater temperature was allowed to
rise to 18°C over a 3-h period as treatment proceeded. In

a subsequent spawning in September 1980, the same

methodology was used, with overnight running seawater

The Veliger, Vols 27, Now

at 13°C and with the temperature of UV irradiated sea-
water rising from 14 to 18°C over a 3-h period. In both
spawnings about 10° eggs were retained in 10 L and treat-
ed as in the spontaneous spawning. About 25,000 veligers
were introduced into each of two 100-L cylindrical fiber-
glass tanks (3 individuals/cm? of wetted tank surface area)
and the rest were discarded. One-third of the water was
changed daily in these tanks and a complete rinse was
done every 10 days.

Settled abalone were given pure cultures of Tetraselmis
suecica as required during the first three weeks of culture.
After this time, film-forming pennate diatoms were added
to the cultures. When juveniles reached an average size of
1.8 mm, they were transferred to seawater trays in a
greenhouse. The abalone fed on naturally occurring dia-
toms that grew in the trays, and upon reaching 5 mm they
were transferred to a 1000-L fiberglass tank at a density
of about one per 500 cm?. There they were maintained
on Lessonia flavicans.

A spawning was induced in September 1980 to dupli-
cate the April 1980 observations; in this test, only early
developmental events were observed. Further spawnings
were made during 1980 and 1981 to check on the seasonal
condition of abalone brought from California and to note
inception of sexual maturity in cultured abalone.

Forage Experiment

Observations of feeding on macroalgae were made to
determine which of three Laminariales combined with
microalgal films promoted the best growth of juvenile ab-
alone. Five groups of 20 abalone having an average size
of 11.2 mm (range = 11.0-11.5 mm) were distributed be-
tween five 20-L aquaria receiving a continuous flow of
sand-filtered seawater at temperatures of 13-17.5°C.

All abalone were given microalgal films cultured on
15 x 20 cm plastic sheets in the following combinations
with species of Laminariales: (Diet A) none, (Diet B) Les-
sonia flavicans, (Diet C) L. nigrescens, (Diet D) Macro-
cystis integrifolia, and (Diet E) all three spp. of macroal-
gae. About 30 g fresh weight of macroalgae pieces were
added to each aquarium along with an algae-covered plas-
tic sheet. Microalgal films consisted mainly of pennate
benthic diatoms with scattered bluegreen algal filaments
and green algal cells. The abalone always had an abun-
dance of food upon which to graze; food was changed
routinely to ensure freshness, and fecal matter and debris
were siphoned off every other day.

The experiment was run for 75 days, and shell length
was measured every 15 days using a millimeter rule, es-
timating to the nearest 0.25 mm. Abalone were handled
using a 10 mm camel’s hair brush to avoid damaging their
delicate shells. Differences between growth on the differ-
ent diets were tested for significance using a Model I
analysis of variance and a Student- Newman-Keuls (SNK)
test (SOKAL & ROHLF, 1969).

B. Owen et al., 1984

Page 103

Table 1

Parameters of early development of Haliotis rufescens obtained in three spawnings in Chile, with comparative values from
the literature. h, hours; d, days.

Spawnings in Chile

Spontaneous Induced Induced* LEIGHTON EBERT & HOUK
Parameter 22 Sept 79 23 Apr 80 9 Sept 80 (1974) (1984)
Blastula (h) — 5 5 5 5
Rotating gastrula (h) 16 — 10-12 13 15
Trochophore emergence (h) 22-24 16 16-24 18-24 20
Veliger stage (h) 40 24 29 48 30
Surface tactile stage (d) 5-8 4 3 4 6
Settlement (d) 8-12 4-7 By), 5-6 7
Notch stage (d) 45 35-40 — 60-70 50
Temperature (°C) 13-18 18 17-19 14-18 15

* Not cultured post-metamorphosis.

RESULTS
Culture Experiments

Spawning: The spontaneous spawning of 22 September
1979 was probably due to one of the small though abrupt
rises in water temperature that occur irregularly in waters
near Coquimbo during spring and summer months
(ALFSEN, 1979). Abalone from the same group spawned
spontaneously in their holding tanks on 9 October 1980
when the temperature of incoming water rose overnight
from 14.2 to 15.5°C. The phenomenon occurred again on
24 October 1981 when ambient seawater temperature rose
from 14.8 to 16°C overnight. In these cases, the female
abalone crawled from the holding tanks while simulta-
neously ejecting ova; males remained below the water sur-
face while releasing sperm.

Abalone were successfully spawned in April, Septem-
ber, and November 1980, and in June, August, and Oc-
tober 1981. In all cases, the abalone spawned within 2 to
4h after exposure to UV-treated seawater. The spawning
of October 1981 included both abalone from California
which had been immature when brought to Chile, and
abalone cultured in Chile which had reached two years
of age. Three-year-old California abalone spawned copi-
ously and produced normal larvae. Of the two-year-old
abalone produced in Chile, only 20% exhibited pigmented
gonadal tissue. They spawned but produced few eggs, and
these failed to be fertilized; no further observations were
made on development of sexual maturity in these abalone.

In all spawnings producing viable zygotes, fertilization
and early development proceeded in accordance with de-
scriptions in the literature. Some parameters of early de-
velopment in three cultures are listed in Table 1.

Survivorship and growth: Mortality was negligible in
larvae cultures. After the larvae had metamorphosed, a
steady attrition of postlarvae began until they neared the
2-mm size. Table 2 lists survivorship and size for the two
groups of cultured abalone. In this table it can be seen

that only 0.4% of the abalone in Group II reached the
1.8-mm size from the veliger. However, survival from the
1.8-mm to the 20-mm size neared 50% over the 12 months
of observation. Abalone surviving to 35 months reached
maximum sizes of 75 mm. All data past 12 months include
fortuitous observations outside the original experimental
design and represent survival and growth of abalone
maintained under less than optimal conditions. Compar-
isons between the two groups of abalone show an almost
equal survival rate when comparing the 6 to 12 month
survival of Group I with the 4 to 12 month survival of
Group II (Table 2).

Shell color of the cultured abalone was uniformly red
and white “candy stripe” to a size of 2 mm. Past this size,

Table 2

Size and age of Halotis rufescens cultured in laboratories
at Coquimbo, Chile, and Monterey, California.

Shell length, mm

Age
Group (months) Mean + SD Range n
If 6 —- — 2.0-16.5 _
12 22.4 + 3 14.0-30.0 270
24 34.545 21.0-48.0 1785
36 53.8 + 6 37.0-75.0 150
1D 2 1.8 — 1.3-2.2 40
4 Dy) ae il 2.0-10.0 1637
6 10.9 — 7.0-16.0 108
12 20.1 + 4 12.0-33.0 970
IlI*** 2 1.8 — 1.2-2.3 50
4 5.0 — 3.0-7.8 50
6 8.1 — 4.5-12.4 50
8 13.0 — 10.5-16.5 50
12 20.5 — 12.2-26.1 50

* Spontaneous spawning; Coquimbo, Chile; Sept. 1979.
** Induced spawning; Coquimbo, Chile; April 1980.
*** Composite of several induced spawnings; Calif. Dept. of
Fish and Game, Monterey, California.

Page 104

GROWTH INCREMENT, mm.

15 30 45 60 75

TIME ,days
Figure 1

Growth of juvenile abalone on five different algal diets. Each
data point represents the mean growth increment for all animals
in each treatment. Diets: A = microalgae (ma); B = Lessonia fla-
vicans plus (ma); C = L. nigrescens plus (ma); D = Macrocystis
integrifolia plus (ma); E = all macroalgae plus (ma).

a complex variation in color developed among the speci-
mens, including white, green, and red pigment, solidly or
in bands. As long as they were provided fresh seawater,
forage, and adequate physical space, the abalone appeared
hardy and free of disease. Growth was retarded in a group
of 5-10 mm abalone that were crowded in a holding tank
at a density of 1-2 per 100 cm’. In spite of this crowding,
the abalone never showed a tendency to crawl out of the
tanks. They resumed normal growth when presented ad-
equate physical space.

Feeding experiment: The diet of microalgae alone pro-
duced the least growth. Different species of macroalgae
gave different growth rates when in combination with

The Veliger, Volo 27/-oNiorwZ

microalgae, and a mixture of all the macroalgae plus mi-
croalgae produced optimal growth (Figure 1, Table 3).
Statistically significant (P= 0.01) differences between
groups appeared beginning at 30 days and continued
through the end of the experiment (Figure 1, Table 3).

DISCUSSION

Breeder and juvenile red abalone from California accli-
matized well to ambient seawater conditions at the Co-
quimbo laboratory. Laboratory tests performed during
1979 and 1980 revealed that the abalone readily accepted
native algal species such as Lessonza flavicans, L. nigres-
cens, Durvillea antarctica, and Gracilaria sp. (EBERT, 1979a,
b, 1980). Abalone growth, feeding rates, and food-conver-
sion efficiency tests were performed using L. flavicans. Ju-
venile red abalone fed this species grew an average of 10.5
mm in shell length (16.5-27.0 mm) during a 7-month
period (EBERT, 1980). This compares favorably with ju-
venile red abalone growth rates observed in California
when giant kelp, Macrocystis spp., a preferred food for
adults, is fed. The juvenile red abalone feeding rate and
food-conversion efficiency on L. flavicans during the same
7-month period noted above averaged 7.57% and 9.36%
of their body weight/day respectively (EBERT, 1980). Our
spawnings showed that at least a portion of the group was
ripe throughout the year, suggesting that these animals
were fecund the year around in Chilean water, as shown
for this species in its California habitat (e.g., BOOLOOTIAN
et al., 1962).

Larvae produced in our first culture settled in 8-12
days, and those of the second and third cultures in 3-7
days (Table 1). The longer delay of the first culture was
unusual and may indicate stress due to temperature vari-
ation under the improvised conditions available at the time.
In subsequent cultures where water temperatures were
stable, settling time was comparable to literature values.
Early abalone development rates in Chile were similar to
those observed in California, although a direct comparison
is somewhat obscured by the variable culture tempera-
tures within and among the various studies (Table 1).

No mass mortalities were ever experienced at any stage

Table 3

Mean sizes of abalone for which incremental growth data are plotted in Figure 1. At time zero, for all abalone x = 11.2,
s = 2.5, n = 20. N, total number per treatment; x, mean length; s, standard deviation.

Time, days

15 30
Diet’ x s n x S n x
A Hak sH 0.34 20 12.4 0.40 20 1622
B 11.8 0.29 20 WAT 0.41 20 13.6
C 11.8 0.29 20 13.0 0.43 20 13.9
D 11.9 0.22 20 13.2 0.41 20 14.3
E 12.0 0.29 19 13.4 0.41 19 14.4

' See Figure 1.

45 60 75

s n xX Ss n X S n
0.55 20 13.8 0.47 20 14.5 0.64 20
0.52 20 14.3 0.52 20 15.0 0.72 20
0.55 20 14.8 0.57 20 15.8 0.60 20
0.50 20 15.2 0.66 20 S7/ 0.68 18
0.44 19 15.3 0.66 18 16.2 0.83 18

B. Owen et al., 1984

in our cultures in Chile, although the constant low level
attrition of postlarvae produced an overall low survival to
the 2-mm size. At the time the first respiratory pore ap-
peared, mortality abated. A similar pattern is usually found
in California abalone culture research and hatchery op-
erations. California cultivators occasionally experience high
postlarval mortalities, presumably from pathogenic bac-
teria. California hatchery operations also suffer high mor-
talities in early juvenile stages due to food depletion by
copepods and depredation by nematodes and other small
invertebrates. For example, the copepod Tigriopus califor-
nicus competes with young abalone for forage and space
and degrades water quality. The role of nematodes is
poorly understood, but they are commonly observed feed-
ing on weakened and freshly dead abalones. None of these
problems was apparent in Chile. Successful hatchery pro-
duction of this abalone in Chile will rely in part on so-
lution of the postlarval attrition problem.

Few abalone of any size were lost due to their crawling
out of the tanks (often a serious problem in some Califor-
nia hatcheries), even at densities as high as one individual
(x = 22 mm long) per 70 cm? tank space. At this density,
microalgal films were rapidly eliminated, probably de-
priving the abalone of critical nutrition, thereby stunting
their growth. SHIBUI (1972) found diatoms to be the op-
timum food for Haliotis discus hanna in the 3 to 10 mm
size range.

Mean growth rates in Chilean produced Haliotis rufes-
cens are similar to those observed in California, at least
during the first year of life. A wide size range is apparent
from all groups of similar age abalone (Table 2).

To our knowledge, this is the first experience of cul-
turing a northern hemisphere haliotid in the southern
hemisphere. These preliminary results suggest there are
no reasons to preclude success in development of Haliotis
cultures in Chile. The lower labor costs and present lack
of legal restrictions may make this culture economically
attractive in Chile in the future. The fate of red abalone
introduced to the Chilean sublittoral has not been exam-
ined. Experimental plantings in suitable habitats have yet
to be conducted. However, laboratory and field experi-
mentation made during the OAS project (EBERT, 1980)
gave indications that such transplants would be successful
and ecologically compatible with the Chilean nearshore
environment. However, further experimentation is rec-
ommended, with a male-only population, prior to any

Page 105

decision to introduce H. rufescens to natural Chilean ma-
rine environments.

ACKNOWLEDGMENTS

This work was supported by the Organization of Amer-
ican States performance contract No. 2981 and by the
Direccion General de Investigaciones of the Universidad
del Norte. We express gratitude to Mr. Helmo Perez Or-
tiz for his unfailing technical support and useful sugges-
tions.

LITERATURE CITED

ALFSEN, J. S. 1979. Descripcion oceanografica de la Bahia La
Herradura de Guayacan. Pub. Occas. No. 1, Centro de
Invest. Submar., Univ. del Norte, Coquimbo. 64 pp.

BOOLOoTIAN, R., A. FARMANFARMAIAN & A. C. GIESE. 1962.
On the reproductive cycle and breeding habits of two west-
ern species of haliotids. Biol. Bull. 122(2):183-193.

Cox, K. W. 1962. California abalones, family Haliotidae. Cal-
if. Dept. Fish Game, Fish Bull. No. 118:113 pp.

EBERT, E. E. 1979a. Introduction of the red abalone, Haliotis
rufescens, into Chile: a feasibility study. Progress report,
contract 2981, Organization of American States, Santiago,
Chile. 14 pp.

EBerT, E. E. 1979b. Introduction of the red abalone, Haliotis
rufescens, into Chile: a feasibility study. Final report, con-
tract 2981, Organization of American States, Santiago, Chile:
24 pp.

EperT, E. E. 1980. Introduction of the red abalone, Haliotis
rufescens, into Chile: a feasibility study. Final report, con-
tract 2981, Organization of American States, Santiago, Chile.
18 pp.

EserT, E. E. & J. Houx. 1984. Elements and innovations in
the cultivation of red abalone, Haliotis rufescens. Aquacul-
ture 39(1-4):375-392.

Kikucul, S. & N. Uxi. 1974. Technical study on the artificial
spawning of abalone, genus Haliotis. No. 2: effects of ultra-
violet irradiated seawater to induce spawning. Bull. Tohuku
Regional Fisheries Res. Lab. 33:79-92.

LEIGHTON, D. 1974. The influence of temperature on larval
and juvenile growth in three species of southern California
abalones. Fish. Bull. 72(4):1137-1145.

Suipul, T. 1972. On the normal development of the eggs of
the Japanese abalone Haliotis discus hannai (Ino) and eco-
logical and physiological studies of its larvae and young.
Bull. Iwate Pref. Fish. Expt. Stat. 2:1-69 (Engl. Transl.).

SokaL, R. R. & F. J. ROHLF. 1969. Biometry. W. H. Free-
man: San Francisco. 776 pp.

The Veliger 27(2):106-119 (October 5, 1984)

TE, VEG
© CMS, Inc., 1984

Multivariate Analysis of Geographic Variation in
Cypraea caputserpentis (Gastropoda: Cypraeidae)
by

BRIAN N. TISSOT!

Biological Sciences Department, California Polytechnic State University,
San Luis Obispo, California 93407

Abstract. A multivariate analysis of geographic variation in Cypraea caputserpentis Linnaeus, 1758,
was initiated to describe morphological variation within and between populations based on adult shell
morphology. Variation within samples from three populations suggests that geographically distant
populations display similar morphological variability in size, degree of lateral and basal callosity, and
number of basal teeth. Although other factors are probably involved, some intralocality variation in
size and callosity appears to be related to the degree of exposure to waves and currents. Variation in
the number of basal teeth is suggested to be a sexual dimorphism.

Along the east and west coastlines of Australia and southeast Africa, in areas of range-limiting
temperature gradients, Cypraea caputserpentis displays clines in shell shape. Along these clines, shell
form becomes progressively more juvenilized and is correlated with decreasing surface seawater tem-
peratures. Specimens of C. caputserpentis from the Hawaiian Islands are distinctly smaller and more
marginated, and possess more numerous basal teeth than individuals from the Indo-Pacific. This unique
variation does not appear to be related to differences in habitat or surface seawater temperatures.
Rather, it is suggested that reproductive isolation of populations in Hawaii has led to the evolution of

a morphologically distinct subspecies, C. caputserpentis caputophidu Schilder, 1927.
Geographic variation is similar to variation within populations and thus supports the hypothesis that
characters variable within populations are adaptively neutral traits likely to be divergent between

populations.

INTRODUCTION

CowRIES comprise a large group of gastropods character-
ized by their colorful, glossy shell and elongate aperture
lined by rows of teeth. As with most gastropods, cowries
display high diversity in shell morphology. Numerous
subspecies display striking examples of infraspecific di-
vergence (SCHILDER, 1967; SCHILDER & SCHILDER, 1938-
1939, 1971). Compounding this genetic variation are high
levels of geographic, ecological, and sexually dimorphic
variation (BROCK, 1980; BURGESS, 1970; FoIn, 1972; Li-
VERSIDGE, 1968; ORR, 1959; RENAUD, 1976; SCHILDER,
1961, 1962, 1969; SCHILDER & SCHILDER, 1961, 1968).
Thus, morphological variation within species can be de-
rived from several sources.

As a result of high variability and a general disagree-

' Present address: Department of Ecology and Evolutionary
Biology, University of California, Irvine, CA 92717.

ment regarding the taxonomic importance of shell char-
acteristics, the taxonomy of cowries is large and confusing.
Subspecies are described for most of the 200 species, nu-
merous species being associated with five or more infra-
specific taxa (ALLAN, 1958; SCHILDER & SCHILDER, 1938-
1939, 1971). However, few of these subspecies are rec-
ognized by many authorities (BURGESS, 1970; FoIn, 1976;
Kay, 1979; TayLor & WALLS, 1975). Clearly, in order
to establish conservative taxonomic characters, relation-
ships between variation in shell morphology and infra-
specific divergence need to be established.

The serpent’s head cowry, Cypraea caputserpentis Lin-
naeus, 1758, represents a good example of a morpholog-
ically variable species associated with a confusing taxon-
omy. Pronounced geographic variation is evident
throughout the broad Indo-Pacific range of this species
(ALLAN, 1958; CATE, 1964, 1969; GRIFFITHS, 1958;
SCHILDER & SCHILDER, 1938-1939). In addition, consid-
erable morphological variation is found between individ-
uals within populations (BURGESS, 1970; Kay, 1957, 1960).

B. N. Tissot, 1984

Page 107

x
oY

Cypraea ae
caputdraconis f, .#

Figure 1

Geographic distribution of Cypraea caputserpentis and C. caputdraconis, and the distribution of samples used in the
statistical analyses. Subspecies described by SCHILDER & SCHILDER (1938-1939:135) are represented by symbols

to facilitate reference to Table 1.

As a result, this species is highly variable both within and
between populations.

The taxonomy of Cypraea caputserpentis reflects this
compounded morphological variation—as many as 15 taxa
have been associated with this species. SCHILDER &
SCHILDER (1971:65) recognize four taxa: one widely dis-
tributed subspecies (C. caputserpentis caputserpentis) for-
merly divided into Indian Ocean, west Pacific, central Pa-
cific, and Japanese subspecies (SCHILDER & SCHILDER,
1938-1939); two clines along the east and west coasts of
Australia (C. c. caputanguis Phillipi, 1849, and C. c. ken-
yonae Schilder & Schilder, 1938, respectively), and one
restricted subspecies (the Hawaiian C. c. caputophidi
Schilder, 1927). In addition, C. caputdraconis Melvill, 1888,
a species endemic to Easter Island and nearby Sala y
Gomez, is believed to have been derived from C. caputser-
pentis (REHDER, 1980; SUMMERS, 1975; TissoT, 1981)
(Figure 1).

The purpose of this study is to describe morphological
variation within and between populations of Cypraea ca-
putserpentis. Using a combination of univariate and multi-
variate statistical techniques, this study focuses on describ-
ing patterns of variation within and between samples from
populations, correlations of patterns with likely causal
factors, and an evaluation of infraspecific divergence. Hy-
potheses relating to causal factors associated with mor-
phological variability are generated based on patterns of

geographic variation, morphological trends in other cow-
ries, and similar morphological patterns in other marine
prosobranchs (see GOULD & JOHNSTON, 1972). An ad-
ditional goal of this study is to test KLUGE & KERFOOT’s
(1973) premise relating character variability and diver-
gence within and between populations; their theory makes
predictions on the origins of geographic variation and sug-
gests relationships between fitness and character variabil-

ity.

MATERIALS anpD METHODS

Specimens of Cypraea caputserpentis were obtained from
a variety of sources (Table 1). Fully adult. specimens with
well developed basal teeth and terminal ridges were se-
lected at random from large samples for measurement.
The analysis included 717 shells from 63 samples (Figure
i);

Shell characters were selected primarily on the basis of
putative subspecific differences (SCHILDER & SCHILDER,
1938-1939) and variables describing shell shape and form.
Eighteen variables were measured (Figure 2). Shell color
was assessed qualitatively. In addition, for the general
area of each collection locality, yearly minimum, maxi-
mum, and average surface seawater temperatures were
obtained from EBER et al. (1968), SVERDRUP et al. (1942),
the U.S. Navy (1944), and WyrTkI et al. (1971).

Page 108 The Veliger, Vol) 277 NewZ

Table 1

Description of Cypraea caputserpentis sample localities. Locality numbers are mapped in Figure 1.

Specimens
Subspe- used in
Locality no. Locality Source & ID no.* cies** analysis
la Natal, South Africa SAM #4739 CAP 5
1b Perrier Rocks, Natal, S. Africa SC CAP 5
2 Point Aux Sables, West Mauritius ANSP #273662 CAP 10
3 South side of Nossi Iranji, NW Madagascar ANSP #257119 CAP 10
4 Seychelles ANSP #2066263 CAP 10
5 Kiwengwa, Zanzibar ANSP #212418 CAP 10
6 Mogadiscio, Somalia ANSP #673870 CAP 10
7 Dehiwala Village, West Sri Lanka ANSP #224983 CAP 10
8 Galle, South Sri Lanka ANSP #210793 CAP 10
9 Near Calcutta, India Sc CAP 8
10 Phuket Island, Thailand ANSP #285855 CAP 10
ili Phuket Island, Thailand SC CAP 10
12 Direction Island, Cocos-Keeling ANSP. #288437 RET 10
13 Cocos-Keeling USNM #589098 REA 10
14 Cocos-Keeling AMS #c.132845 RET 10
15 Bali RF RET 10
16 Radar reef, west Rottnest Island WAM #1473-81 KEN 10
LY East Wallaby Is., Abrolhos Islands WAM #1470-81 KEN 357
18 Sunday Is., SE of Dirk Hartog Is. WAM #1469-81 KEN 10
19 North end Dorre Island WAM #1468-81 KEN 10
20 Quobba Point ANSP #238540 RET 10
Zi Point Charles ANSP #267948 RET 10
22 Cape Cuvier ANSP #267817 RET 10
23 Four miles north of Red Bluff ANSP #268055 RET 10
24 Bill Bay WAM #1472-81 RET 10
25 South end Flacourt Bay, Barrow Is. WAM #394-67 RET 10
26 Kendrew Is., Dampier Archipelago WAM #1467-81 RET 10
27 Broome SC RET 10
28 Broome WS RET 10
29 Beagle Bay AMS #c.85458 RET 10
30 Sunday Island WAM #1471-81 RET 10
31 Yampi Sound WAM #1466-81 RET 10
32 Fairfax Island AMS #c.69053 ANG 10
33 Wooli AMS #c.101321 ANG 10
34 Long reef, Sydney AMS #c.75444 ANG 10
35 Lord Howe Island AMS #c.109335 ANG 10
36 Latuhalalat, Ambon JWW RET 10
37 Cebu TSS RET 10
38 Chiquita Island, near Subic Bay BNT #225-232 RET 10
39 Ishigaki Shima EAK RET 10
40 Okinawa USNM #670301 RET 10
41a Bolo Point, Okinawa VP RET 15+
41b Bolo Point, Okinawa SC RET ott
42 Tanabe, Nagasaki ANSP #119907 MIK 10
43 Ku, Japan SC MIK 10
44 Rabaul, New Britain Sc RET 10
45 Ranonggar, Solomons SC RET 10
46 Fiji RF ARG 35F
47 Kwajalein Sc ARG 10
48 Majuro Sc ARG 10
49 Majuro, leeward side EAK ARG 10
50 Reef West, Canton Island USNM #617097 ARG 10
51 Paea, Tahiti SC ARG 10
52 Taiaro EAK ARG 8
53 Raroia EAK ARG 10
54 Marquesas ANSP #80037 ARG 10
55 Taiohae Bay, Nukahiva USNM #700183 ARG 10
56 Jarvis Island ANSP #315681 ARG 10

B. N. Tissot, 1984 Page 109

Table 1 (Continued)

Specimens

Subspe- used in

Locality no. Locality Source & ID no.* cies** analysis
57/ Christmas Is. EAK ARG 10
58 English Harbor, Fanning EAK ARG 10
59a Palmyra Island USNM #348454 ARG 5
59b Palmyra Island USNM #487392 ARG 6

60 Wake Island EAD ARG 35T
6la Honokahua Bay, Maui JRS PHI 6
61b Honokahua Bay, Maui BNT PHI 3
62 Fort Kamehameha Reef, Oahu Sc PHI 10
63 Honolulu Harbor, Oahu AMNH PHI 10
Total 717

* Sources are abbreviated as follows: ANSP, Academy of Natural Sciences, Philadelphia; AMNH, American Museum of Natural
History, New York; AMS, The Australian Museum, Sydney; BNT, Brian N. Tissot; EAD, Edward A. Dunlap; EAK, E. Alison
Kay; JJW, J. J. Wenno; JRS, John R. Steinbeck; RF, Robert Faniel; SAM, South African Museum, Cape Town; SC, The Shell
Cabinet, Falls Church, VA; TSS, The Shell Shop, Morro Bay, CA; USNM, United States National Museum, Washington, DC;
WAM, The Western Australian Museum, Perth; WS, Westralian Shells, Broome, WA; VP, Viola Perrault.

** Samples are classified to subspecies according to SCHILDER & SCHILDER (1938-1939:135) to facilitate reference to Table 3.
Subspecies are represented by symbols in Figure 1. The following acronymns are used: CAP, Cypraea caputserpentis caputserpentis
Linnaeus, 1758; KEN, C. caputserpentis kenyonae Schilder & Schilder, 1938; ANG, C. caputserpentis caputanguis Philippi, 1849; RET,
C. caputserpentis reticulum Gmelin, 1791; ARG, C. caputserpentis argentata Dautzenberg-Bouge, 1933; MIK, C. caputserpentis mikado

Schilder & Schilder, 1938; PHI, C. caputserpentis caputophidu Schilder, 1927.
+ Used in single sample analyses. For between sample analysis, sample size was randomly reduced to 10 individuals.

+t Used in juvenile analysis.

The data were examined using a combination of uni-
variate, multivariate, and trend analyses. Due to small
sample sizes the canonical analysis of discriminance could
not be used as in previous analyses (TISSOT, 1981).

Univariate methods consisted of analysis of variance
between groups and a Student-Newman-Keuls multiple
range test for each variable. One-way analysis of variance
was used to determine significant differences for each vari-
able between localities. Significant variables were ana-
lyzed by Student-Newman-Keuls multiple range tests
(SOKAL & ROHLF, 1969) to separate localities into ho-
mogeneous subsets for each character.

Variation within and between samples was analyzed
using principal component analysis (PCA). Variables in
this study had different units of measurement (7.e., mm or
degrees), and, therefore, the data were transformed to
z-scores prior to analysis by PCA. Variation within three
samples was examined using multigroup PCA (PI-
MENTEL, 1979). This technique involves the comparison
of angles (PIMENTEL, 1979) or correlations (RUMMEL,
1970) between sample principal components and compo-
nents derived from pooled within-group dispersion (2.e.,
pooled correlation matrix). Sample components that dis-
play significant correlation with those of pooled dispersion
describe similar intralocality variation.

In a second analysis of variation between samples, data
were examined by nonmetric multidimensional scaling
(MDS). MDS is a nonlinear, nonparametric, iterative
multivariate technique that resolves small group differ-

ences and provides a better placement of individuals rel-
ative to each other than does PCA (ROHLF, 1972; PI-
MENTEL, 1981). In this study, results of analysis by MDS
are contrasted with results obtained using PCA.

The multivariate technique of canonical correlation was
used to determine correlations between shell morphology
and seawater temperature as previously observed in cow-
ries (BROCK, 1980; FoIN, 1972; LIVERSIDGE, 1968; SCHIL-
DER, 1961; WILSON & SUMMERS, 1966). Canonical cor-
relation maximizes linear correlations between two related
data sets. Dimensions are defined to portray the largest
correlations between data sets relative to no correlation
within data sets. Examples of this approach can be found
in CALHOON & JAMESON (1970), MurRpPHy (1972), and
PHILLIPS et al. (1973).

Trends in geographic variation were examined by poly-
nomial trend surface analysis (PTSA), a technique that
reduces large data sets to visual patterns, which often pro-
vide insight into underlying causal factors contributing to
geographic variation (MARCUS & VANDERMEER, 1966).
PTSA consists of fitting a least-squares polynomial sur-
face to the data so that coordinates of a locality (latitude
and longitude) can be used to predict the value of a vari-
able. This variable can be a single character or a multi-
variate measure such as a principal component score or
MDS axis coordinate (SNEATH & SOKAL, 1973; THORPE,
1976). PTSA models are fitted for various degree poly-
nomials, with residual variation and the proportion of
variation explained by each trend surface providing aids

Page 110

for interpretation (MATHER, 1976). Geographic trends are
represented by the contour plot while local variation and
sampling error are displayed in the residuals (MARCUs &
VANDERMEER, 1966).

The analyses were made using the computer systems at
California Polytechnic State University, San Luis Obispo,
California. The computer program DISANAL (PI-
MENTEL, 1979) was used for the analysis of variance, Stu-
dent-Newman-Keuls multiple range test, and PCA. The
program BMDP-6M (Dixon & BRown, 1979) was used
for the canonical correlation analysis. Programs MDS and
PTSA, both based on algorithms in MATHER (1976) mod-
ified by Pimentel, were also used.

RESULTS

Principal component analysis of three single samples and
their pooled dispersion produced principal components
significantly correlated (P < 0.05) with components de-
rived from an analysis of all 63 samples (Tables 2, 4).
Thus, geographic variation between samples involves traits
also variable within samples derived from three localities.

Variation within Samples: Multigroup PCA

Patterns of variation within samples from three popu-
lations—Fiji, Wake, and Wallaby (samples #46, 60, and
17 respectively, see Figure 1)—were analyzed using mul-
tigroup PCA. These samples were selected because they
were large, each consisting of 35 individuals, and geo-
graphically distinct. The goal of this analysis is to examine
similarities and differences in morphological variation oc-
curring within samples from single populations.

Sample correlation matrices are significantly different
(test of homoscedasticity, P < 0.01). Results of PCA? on
each sample and their pooled dispersion indicate that three
components for each sample and four for pooled disper-
sion describe a large percentage (>70%) of the total vari-
ation among variables and individuals (Table 2). In ad-
dition, interpretive aids for PCA (PIMENTEL, 1979)
indicate that these components have high correlations with
the original variables, and possess significantly different
eigenvalues. Thus, the following components describe most
of the meaningful information derived from variation
within the data.

The first component derived from pooled dispersion ac-
counts for almost 50% of the total variation and describes
variation attributable to differences in general size of ma-
ture cowries (Table 2). A small eigenvector coefficient for
shell angle indicates that lateral callosity (shell material
added laterally) is independent of size; hence, shell shape
is not appreciably different between large and small in-
dividuals. Size variation in all three samples is very sim-
ilar: first components of all samples and pooled dispersion
are significantly correlated (all r > 0.98).

* Detailed output available from author upon request.

The Veliger, Vol. 27, No. 2

Table 2

Variation within samples of Cypraea caputserpentis: prin-

cipal components derived from pooled dispersion of three

samples: Wake, Fiji, and Wallaby. Minor eigenvector coef-
ficients have been omitted for clarity.

Eigenvectors for principal components

1 2 3 4
Number
General Lateral Basal of basal
Variable size callosity callosity teeth
Length 0.331 — a —
Width 0.311 — — —
Height 0.310 — = —
Spire length 0.326 — - —
Dorsal blotch
length 0.311 _- — —
Dorsal blotch
width 0.275 —0.228 — —
Shell angle = —0.570 — —
Aperture width 0.163 —0.342 — —
Height to margin 0.139 — 0.541 —0.419
Anterior right
ridge 0.238 0.311 _ —
Anterior left
ridge 0.282 — — —
Posterior right
ridge 0.239 0.228 — —
Posterior left
ridge 0.237 — — 0.464
Number of labial
teeth 0.178 — — —0.407
Number of col-
umellar teeth 0.150 — 0.407 =0,57/6
Length of col-
umellar tooth 0.157 — —0.546 —
Outlet height 0.206 —0.315 — =
Width of dorsal
spot — —0.323 — —
Percentage of
total variation 48.8 13.2 6.5 S57/
Cumulative
variation 48.8 62.0 68.5 74.2

Variation in shell shape is described by the second and
third components of pooled dispersion. Pooled dispersion
separates shape variation into two distinct components:
differences between individuals in the degree of margin-
ation (lateral callosity), and variation attributable to the
shape of the base (basal callosity) (Table 2). Variation in
lateral callosity is indicated by large eigenvector coefh-
cients for shell angle and blotch width; all three samples
have components describing variation in lateral callosity.
Differences in basal callosity, described by variation in
the height of the base to the margin and length of the mid-
columellar teeth (see Figure 2), is evident in components
derived from the Fiji and Wallaby samples. Thus, vari-
ation in adult shell shape is very similar in each sample.

B. N. Tissot, 1984 Page 111

y The only difference is the absence of variation in basal
callosity between individuals in the sample from Wake
al Island.

The fourth principal component of pooled dispersion
depicts further similarity between samples describing
variation in the number of basal teeth and, to a lesser
extent, basal callosity (Table 2). PCA of all three samples
produced components describing similar variation (7 >
0.68). In general, individuals with more numerous labial
and columellar teeth possess a more callous base.

Blotch Length) ~~

ij Length
- |Spire Length g

Variation between Samples: Univariate Analysis

The results of a one-way analysis of variance for each
variable showed significant differences among the 63 sam-
ples for all 18 variables (all P < 0.01). A Student-New-
man-Keuls multiple range test separated character means
! 1 into overlapping subsets. There was little congruence be-
tween variables in terms of geographic variation. In fact,

be ao ao using single variables it was impossible to resolve geo-
graphic patterns using PTSA. Results for two of the most
variable characters, shell length and shell angle, will be
j f used as an example (Table 3).
nigitee CORRE | EN Based on shell length, the multiple range test produced
Bee anlenogtethiRidge no unique subsets. Rather, all subsets overlap consider-

ably with adjacent subsets indicating large intra- and in-
ter-locality variation (Table 3). Samples composed of small
individuals occur primarily in a broad equatorial belt ex-
tending from French Polynesia to Sri Lanka, bordered in
the Pacific by the Hawaiian and Ryukyu Islands to the
north and Indonesia to the south. The largest shells of
this species are found in the Cocos-Keeling Islands, east
Africa, New South Wales (Australia), and Western Aus-
tralia. The largest shell measured 44.2 mm (Bill Bay,
Western Australia), the smallest adult 19.5 mm (Moorea,
etcimes French Polynesia).

Bs Based on shell angle the multiple range test separated
samples into three homogeneous subsets (Table 3). Shells
with large angles are unmarginated and inflated, all ju-
venile characteristics, and are found among individuals
from the southern range extremes: New South Wales
(Australia), South Africa, and Western Australia. Indi-
viduals from Wooli and Sydney, both New South Wales,

Baas rm Sra ae have large shell angles significantly different from each

other and from those found in other areas (Table 3). Thus,

a steep cline in shell shape is evident along the east coast

of Australia.

F Labial
F Teeth

Posterior
Right
Ridge

7
Variation between Samples: Multivariate Analysis
‘ Results of PCA on 63 samples (621 individuals) are
Li? S found in Table 4. Interpretive aids indicate that the first
ois Ss es Height
ff f : : ' Height to Margin Vee
a | a
aie igure 2
a Shell Angle a) veer

ot Morphometric variables used to describe the shell of Cypraea
caputserpentis. Drawing by David W. Behrens.

Page 112 The Veliger, Vol. 27, No. 2

Table 3

Variation between samples of Cypraea caputserpentis: Student- Newman-Keuls Multiple Range Test for two morphological
variables: shell length and shell angle. Non-significant ranges are connected by a vertical line. For a description of locality
numbers and subspecific designations see Table 1.

Shell length Shell angle
Locality Locality
no. Subspecies Mean value Significant ranges no. Subspecies Mean value — Significant ranges
49 ARG 26.7 51 ARG 42.3
BY RET Die 14 RET 44.3
51 ARG 27.6 36 RET 44.4
44 RET QT] 10 CAP 44.8
28 RET 27.8 50 ARG 45.4
45 RET 27.9 42 MIK 45.5
61 PHI 28.1 12 RET 45.7
62 PHI 28.1 49 ARG 45.8
7 CAP 28.2 9 CAP 46.0
2 CAP 28.5 45 RET 46.2
58 ARG 28.7 56 ARG 46.2
63 PHI 29.1 48 ARG 46.8
15 RET 29.4 13 RET 46.9
43 MIK 29.4 43 MIK 47.0
25 RET 29.5 60 ARG 47.3
47 ARG 29.6 59 ARG 47.5
36 RET 29.6 57 ARG 47.7
D7. RET 29.9 44 RET 47.7
39 RET 29.9 8 CAP 47.9
52 ARG 30.0 3 CAP 48.2
50 ARG 30.1 55 ARG 48.2
38 RET 30.3 11 CAP 48.2
17 KEN 30.4 27 RET 48.4
54 ARG 30.4 47 ARG 48.5
46 ARG 30.7 39 RET 48.6
57 ARG 30.9 15 RET 48.9
33 ANG 31.0 25 RET 49.0
40 RET 31.3 53 ARG 49.0
B35 ANG 3163 55 ARG 49.2
3 CAP 31.7 26 RET 49.3
48 ARG 31.8 46 ARG 49.3
41 RET 31.8 38 RET 49.5
42 MIK 31.8 24 RET 49.6
59 ARG 31.9 28 RET 49.7
6 CAP 31.9 29 RET 50.1
8 CAP 31.9 Sif, RET 50.2
9 CAP 32.0 62 PHI 50.4
23 RET 32.1 4 CAP 50.5
20 RET 32.1 61 PHI 50.9
53 ARG 32.1 5 CAP 51.6
16 KEN 3242) 21 RET 51.6
32 ANG 32.4 6 CAP 52.0
19 KEN 32.4 40 RET 52.0
24 RET 32.7 18 KEN 52.8
11 CAP 32.9 32 ANG 5O x
60 ARG 33.3 63 PHI 53.2
10 CAP 33.4 23 RET 53.3
26 RET 33.4 54 ARG 53.4
31 RET 33.4 41 RET 53.7
29 RET 33.5 7 CAP 53.9
5 CAP 33.5 30 RET 54.0
12 RET 33.7 31 RET 54.0
De. RET 33.8 20 RET 54.7
18 KEN 33.9 22 RET 56.3
21 RET 34.4 58 ARG 57.3

B. N. Tissot, 1984

Page 113

Table 3 (Continued)

Shell length

Locality
no. Subspecies Mean value Significant ranges
18 KEN 34.5 |
1 CAP 34.7
14 RET 34.9
13 RET 35.0
4 CAP B52
34 ANG 3)
56 ARG 35.6
55 ARG 36.2

three principal components describe a large percentage of
the total variation among variables and individuals. For
this reason three axes were obtained using the MDS al-
gorithm (see MATHER, 1976). Graphs of locality centroids
(=multivariate means) based on principal component scores
were very similar to ordinations obtained using MDS.
Since MDS provided a greater spread of groups and is
theoretically preferred over PCA, the MDS ordination
will be discussed in reference to the PCA vectors.

The first principal component (Table 4), accounting for
approximately 50% of the total variation, separates local-
ities based on differences in mean size. Geographic pat-
terns based on the first component are similar to those
described previously using shell length. Equatorial sam-
ples do not differ in size, nor do samples in the southern
range extremes, which are intermediate in mean size. In-
dividuals from Hawaiian samples, however, are distinctly
smaller (Table 3). The extent of variation in general size
between geographically adjacent samples and between
replicate samples for the same locality was sufficiently
great to prevent the use of PTSA in formulating a trend
surface analysis of size.

The second principal component contrasts individuals
that differ primarily in the degree of lateral callosity,
length, size of terminal ridges, and width of aperture (Ta-
ble 4). These characteristics describe juvenile shell mor-
phology as indicated by a significant correlation (7 = 0.69,
P < 0.05) between this component and one describing
shape differences between adults and juveniles in a sample
from Okinawa. Ordinations of samples on the second MDS
axis differentiate east Australian samples from most other
samples. Southwest Indian Ocean (Natal and Mauritius)
and Western Australian samples are also unique on this
axis, although to a lesser extent. A trend surface analysis
of sample scores on the second MDS axis displays geo-
graphic patterns (Figure 3).

On the trend surface map (Figure 3) numbers 26 in-
dicate the degree to which an area follows a particular
trend, while numbers <5 indicate the degree to which an
area deviates from the trend (7.e., displays the opposite
pattern of variation). Dots symbolize values intermediate

Shell angle
Locality

no. Subspecies Mean value Significant ranges
16 KEN 57.4

2 CAP Bi)

M7 KEN Bat
35 ANG 58.7
19 KEN 60.0

1 CAP 62.5
34 ANG 69.5 |
33 ANG 73.0 |

in magnitude between two numbers. MDS coordinates of
zero ($ symbol) indicate areas displaying no variability in
the pattern being examined.

The trend map in Figure 3 was created using a fifth
order polynomial model and explains approximately 70%
of the variation between samples present in the second
MDS axis. Samples from the equatorial region do not

Table 4

Variation between samples of Cypraea caputserpentis:

principal components derived from 63 samples (621 in-

dividuals). Minor eigenvector coefficients have been omit-
ted for clarity.

Eigenvectors for principal
components

1 7) 3

Number
General Lateral of basal

Variable size callosity _— teeth
Length 0.336 —0.315 —
Width 0.307 — —
Height 0.324 a —
Spire length 0.328 — —
Dorsal blotch length 0.302 — —
Dorsal blotch width 0.266 —0.290 —
Shell angle os —0.570 —
Aperture width 0.195 —0.280 —
Height to margin 0.146 _ —
Anterior right ridge 0.248 0.301 —
Anterior left ridge 0.291 — —
Posterior right ridge 0.219 0.334 —
Posterior left ridge 0.245 _ --
Number of labial teeth 0.134 _ —0.524
Number of columellar teeth 0.103 _ —0.631
Length of columellar tooth — — —
Outlet height 0.248 — —
Width of dorsal spots — — —
Percentage of total

variation 47.2 SZ 6.9

Cumulative variation 47.2 60.4 67.3

Page 114

The Veliger, Vol. 27, No. 2

44°
4444437
12.444

Ht tt Ut tH oF
Bh tt HE tH et ttt
Ut Ht ot tit tH

Figure 3

Geographic trends in lateral callosity of Cypraea caputserpentis shells: fifth order polynomial trend surface of sample
scores on the second MDS axis. Numbers =6 indicate areas displaying increased juvenilization. Numbers <5
indicate increasing lateral callosity. The $ symbol indicates areas displaying neither pattern. Dots symbolize values

between two numbers.

exhibit appreciable variation. Rather, the trend applies to
all range extremes except Japan. Along the east coast of
Australia a steep cline in lateral callosity is indicated by
a close spacing of contours and rapid change in numbers.
Similar clines exist along the southeast African and west
Australian coasts. Southward in these clines, shell shape

becomes progressively more juvenile (see Figure 4). In the
Hawaiian Islands the opposite trend is indicated: shells
are more marginated, smaller, and wider, and have nar-
rower apertures, larger terminal ridges, and more labial
teeth.

Using PTSA, additional features of each axis not dis-

Figure 4

East Australian Cypraea caputserpentis. Specimens (left to right) are from Fairfax Island, Lord Howe Island,

Wooli, and Sydney.

B. N. Tissot, 1984

Page 115

Figure 5

Geographic trends in the number of basal teeth on Cypraea caputserpentis shells: fifth order polynomial trend
surface of sample scores on the third MDS axis. Numbers =6 indicate areas displaying an increasing number of
basal teeth. Numbers <5 indicate decreasing numbers of basal teeth. The $ symbol indicates areas displaying
neither pattern. Dots symbolize values between two numbers.

played in the trend map can be obtained by examining
the distribution of samples with high residuals. Samples
with high residuals on the second MDS axis trend surface
are, for the most part, randomly distributed geographi-
cally. These samples may represent sampling error, or
perhaps locally unique areas.

The third principal component contrasts samples that
differ primarily in the number of basal teeth (Table 4).
Ordination of samples on the third MDS axis indicates
variation is attributable primarily to samples from the
Hawaiian Islands. In addition, Wooli (New South Wales,
Australia), Natal (South Africa) and two samples from
Western Australia also exhibit this pattern of variation.

Trend surface analysis of scores on the third MDS axis
(Figure 5) accounts for 63% of the overall variation using
a fifth order polynomial model. Clines involving the num-
ber of basal teeth are evident between Hawaii and the
central Pacific, and to a lesser extent along the southwest
Australian and southeast African coasts. Individuals from
the Hawaiian Islands differ markedly from the adjacent
Line Islands (Figure 5). Samples with high residuals are
not geographically randomly distributed on this trend sur-
face. Rather, the residuals serve to contrast specimens from
the Line Islands even more strikingly from those of the
Hawaiian Islands (.e., they indicate a steeper cline). Fur-
thermore, the presence of Western Australian and South
African clines on the third axis represents artifacts of the
methodology; high residuals for the majority of samples
on these coasts indicate that clines are an artifact of out-
lyers (2.e., the Rottnest Island and Natal samples). Thus,
this axis primarily describes differences due to unique
Hawaiian Island samples.

Canonical correlation analysis shows statistically sig-

nificant relationships between shell morphology and sea-
water temperatures (Table 5). Variable loadings indicate
that shell shape (lateral callosity) varies along a temper-
ature gradient. Specimens from the equatorial region, the
warmer part of the gradient, possess a wide, marginated,
relatively low shell. Samples from New South Wales
(Australia), Western Australia, and South Africa, the
colder regions of the gradient, exhibit unmarginated, in-
flated shells associated with low surface seawater temper-
atures. Hawaiian samples do not display this correlation;
they ordinate close to the origin. Canonical variate scores
are significantly correlated (r = —0.60, P < 0.05) with
second MDS axis scores. Thus, clines in lateral callosity
indicated in Figure 3 are significantly correlated with
changing surface seawater temperature.

Table 5

Canonical correlation: relationships between shell mor-

phology and surface seawater temperatures as derived from

63 samples of Cypraea caputserpentis. Minor variable
loadings have been omitted for clarity.

Variable Variable loadings
Maximum temperature 0.946
Average temperature 0.929
Minimum temperature 0.828
Dorsal blotch length —0.449
Dorsal blotch width = 03522
Shell angle —0.839
Aperture width —0.485
Canonical correlation 0.788

Page 116

Variation between Samples: Shell Color

Shell color is also associated with temperature gradi-
ents. In general, individuals from the colder regions of the
gradient, South Africa, southwest Australia, east Austra-
lia, Japan, and Hawaiian Islands, were frequently darker
than average and possessed pigmentation in the interstices
of the basal teeth. Characteristics such as darkened ter-
minal blotches and the extent of pigmentation near the
aperture were also most frequent along the periphery of
distribution. Posterior outlet blotch color displayed marked
geographic variation: all specimens from the eastern In-
dian Ocean (7.e., Thailand, India, and Sri Lanka) pos-
sessed a rich orange blotch, not the usual pale gray one.
A few individuals from Madagascar, Seychelles, and
Western Australia also displayed an orange blotch.

DISCUSSION

Results of statistical analyses suggest that variation in size,
callosity, and the number of basal teeth is prominent with-
in populations of Cypraea caputserpentis. Similar variation
is found between populations in the form of mosaics (size),
clines (lateral callosity), and disjunct distributions (num-
ber of basal teeth). Discussion will first focus on possible
causal mechanisms promoting morphological variation
within and between populations. Subspeciation and char-
acter divergence will then be treated.

Variation within Populations

Multivariate analysis of samples indicates that similar
patterns of morphological variation exist within geograph-
ically distant populations. These intra-locality variations
may represent adaptations to environmental heterogeneity
(e.g., VAN VALEN, 1965), random genetic variation inde-
pendent of significant adaptive value (e.g., DOBZHANSKY
et al., 1977), or the result of disruptive selection (e.g.,
STRUHSAKER, 1968). Results of this study cannot directly
distinguish between these, or any other, alternative hy-
potheses. However, based on studies of other cowries, some
inference concerning causal factors promoting morpholog-
ical variation within populations can be made.

Other than size, the predominant pattern of variation
within samples results from differences in shell callosity.
Variability in lateral and basal callosity was reported by
OrR (1959) for Cypraea annulus Linnaeus, 1758, in Zan-
zibar: wide, heavily callused individuals occur where cur-
rents and wave action are strong, and narrow, unmargin-
ated individuals occur in sheltered bays and on muddy
reefs. Personal observations on several populations of C.
caputserpentis in the Philippine and Hawaiian Islands
suggest a weak positive correlation between exposure to
waves and currents and the extent of overall callosity. As
the range of habitats occupied by C. caputserpentis is con-
siderably less than that of C. annulus, it is not surprising
that variation in the callosity of C. caputserpentis is less
extreme. However, in addition to variation being corre-

The Veliger, Vol. 27; Nos2

lated with exposure, considerable variation in callosity ex-
ists between individuals of C. caputserpentis collected in
the same general area (FANIEL, 1978; personal observa-
tions). Although microhabitat differences between indi-
viduals may be pronounced, it is not readily apparent that
the majority of variation in callosity in C. caputserpentis
is directly related to environmental exposure gradients as
is suggested for C. annulus and numerous other species of
marine prosobranchs (CROTHERS, 1982; HELLER, 1976;
PHILLIPS et al., 1973; STAIGER, 1957; STRUHSAKER, 1968;
TissoT & STEINBECK, 1983; VERMEIJ, 1978).

The number of basal teeth also varies within popula-
tions but relationships to environmental or ecological pa-
rameters are unclear. Variation in the number of basal
teeth could represent an adaptation to predators, although
experiments suggest that some major predators (crabs)
attack the shell by crushing the dorsal surface (VERMEIJ,
1978). SCHILDER & SCHILDER (1961) find the number of
columellar teeth to vary between sexes of Cypraea moneta
Linnaeus, 1758, and C. annulus. Similar morphological
variation is also found in C. spadicea Swainson, 1823
(Dunn & Tissot, unpublished data). Thus, intralocality
variation involving the number of basal teeth in C. caput-
serpentis may represent a sexual dimorphism.

Geographic Variation

Overall size in Cypraea caputserpentis follows a geo-
graphic trend that has been described for shell length in
C. arabica Linnaeus, 1758, C. tagris Linnaeus, 1758, and
C. errones Linnaeus, 1758 (FOIN, 1972; SCHILDER, 1961,
1962; SCHILDER & SCHILDER, 1968): a central equatorial
zone of small-shelled populations surrounded by popula-
tions possessing larger shells at the range periphery. Cy-
praea caputserpentis deviates from this general cypraeid
pattern in one major way: populations in Hawaii possess
a small shell.

Orr (1959) reported shell length in Cypraea annulus to
vary inversely with degree of exposure to waves and cur-
rents of a sufficient magnitude to ‘mask’ geographic vari-
ation. Personal observations suggest that size variation
within populations of C. caputserpentis is similar. As a
result size displays a mosaic geographic pattern, evidenced
by variation between replicate and adjacent samples and
the inability of PTSA to fit a global trend map of general
size. The implication is that individual size is a result of
local parameters (e.g., diet, habitat, wave shock, and water
movement) as well as global parameters (e.g., water tem-
perature and distribution of predators).

Clinal variation in the extent of lateral callosity is cor-
related with changing surface seawater temperatures and
parallels the development of adult shell characteristics.
Along east Australia, Western Australia, and southeast
Africa, individuals within populations exhibit a similar
progressive change in shell form as they range south (Fig-
ure 4). Other species of cowries (Cypraea erosa Linnaeus,
1758, C. vitellus Linnaeus, 1758, C. felina Gmelin, 1791,

B. N. Tissot, 1984

and C. gracilis Gaskoin, 1849, in east Australia; C. mar-
ginalis Dillwyn, 1827, C. helvola Linnaeus, 1758, and C.
erosa on the southeast coast of Africa) appear to exhibit a
similar morphological trend (LIVERSIDGE, 1968; SCHIL-
DER, 1969; SCHILDER & SCHILDER, 1938-1939, 1967).
Given that all three clines in C. caputserpentis display a
similar trend, as well as at least six other species of cow-
ries, a common factor is likely to be responsible. As each
species occupies different habitats, and presumably has
different predators, unique diets, and different dispersal
characteristics, it is unlikely that these clines are main-
tained directly by natural selection. Instead, the induction
of juvenile characteristics by environmental parameters is
suggested.

Many clines in mollusks appear to result from the ef-
fects of water temperature gradients on shell growth and
development (FRANK, 1975; LIVERSIDGE, 1968; PHILLIPS
et al., 1971; VERMEIJ, 1978; WILSON & SUMMERS, 1966).
Cold-water populations of several gastropods show slower
growth rates and a longer life span than do warmer water
populations (FRANK, 1975; KENNy, 1983). If growth is
similar in Cypraea caputserpentis, then the proportion of
juvenile shells in cold-water populations would tend to
increase. Thus, correlations between temperature and
growth rate could be a factor promoting clinal variation.

Alternatively, slower growth may induce juvenile char-
acteristics by causing doming of the shell, a result of coil-
ing (VERMEIJ, 1978). This effect, together with the in-
creased metabolic energy required to precipitate calcium
in colder waters (SVERDRUP et al., 1942) could explain
inflated, unmarginated shell morphology. A growth ex-
periment using individuals from populations along a cline,
in which growth rates and reproduction are monitored at
several temperatures, could clarify the mechanisms in-
volved. At any rate, correlations between shell morphology
and surface seawater temperature suggest that clines in
Cypraea caputserpentis are for the most part a result of the
effects of water temperature on shell growth and devel-
opment. For this reason the Australian subspecies, C’y-
praea c. caputanguis and C. c. kenyonae, should not be
recognized as valid taxa.

Geographic variation in the number of basal teeth is
largely based on samples from the Hawaiian Islands.
Overall, specimens of Cypraea caputserpentis from the
Hawaiian Islands are different in numerous ways from
those in the Indo-Pacific. In contrast to most species of
Hawaiian cowries—e.g., C. tigris (BROCK, 1980; FOoIN,
1972; Kay, 1961a; SCHILDER, 1962)—Hawaiian C. ca-
putserpentis are distinctly smaller (Table 3). In addition,
Hawaiian shells are more marginated, wider, and darker
in color, and have a narrower aperture and larger ter-
minal ridges, a unique situation compared to shells from
southern clines associated with similar seawater temper-
atures (Figure 3). Finally, and perhaps more importantly,
basal teeth are remarkably more numerous on Hawaiian
shells when compared to those found in other areas, es-
pecially from the adjacent Line Islands (Figure 5).

Page 117

Morphological variation attributable to Hawaiian Cy-
praea caputserpentis does not appear to be habitat related
as this species occupies similar habitats throughout its
range (unpublished data). In addition, based on canonical
correlation analysis, variation does not appear to be tem-
perature related. Given the geographically isolated posi-
tion of the Hawaiian Islands and the limited dispersal
ability of the pelagic larvae (12 h in Hawaiian individuals;
Kay, 1957), the morphology of Hawaiian C. caputserpen-
tis is a likely result of reproductive isolation from adjacent
populations. For these reasons, C. caputserpentis caputo-
phidu should be recognized as a valid subspecies. Taxo-
nomically these results agree with the univariate study of
GRIFFITHS (1958).

Subspeciation

Currents near the Hawaiian Islands flow to the south-
west, creating a barrier between Hawaii and the adjacent
Line Islands (ZINSMEISTER & EMERSON, 1979). The ab-
sence of Cypraea caputserpentis from Johnston Island (R.
E. Brock, E. A. Dunlap, personal communications), an
atoll midway between the Line and Hawaiian Islands,
and the predominantly Hawaiian marine fauna at John-
ston (BAILEY-BROocK, 1976; BRock, 1980; BUGGELN &
TsuDA, 1966; EDMONDSON et al., 1925; GOSLINE, 1955)
suggest colonization from another area. Affinities of the
Hawaiian molluscan fauna with those of the west Pacific,
as well as the distribution of cowries in the Hawaiian
islands, suggest colonization from the west (Kay, 1961b,
1967)—a distance well over 4000 km. One hypothesis,
advocated by ZINSMEISTER & EMERSON (1979), suggests
a reduction of this large open-water barrier during the
Pleistocene when lower water levels created habitable is-
lands from several of the Emperor Seamounts (the north-
west end of the Hawaiian chain). Colonization of these
islands could have promoted the establishment of popu-
lations of C. caputserpentis in Hawaii; subsequent sub-
mergence would have severed gene flow from the west
Pacific. High levels of subspecific endemism in Hawaiian
Cypraea (38%; SCHILDER & SCHILDER, 1971) also suggest
recent isolation and perhaps colonization in a similar
manner.

Character Divergence

Significant correlations between principal components
derived from single samples with those derived from 63
samples suggest that patterns of morphological variation
within populations of Cypraea caputserpentis are similar
to patterns of geographic variation. This similarity sug-
gests that geographic variation has arisen from population
variation, an evolutionary phenomenon advocated by
KLUGE & KERFOOT (1973). These authors maintain that
character variability within populations is inversely pro-
portional to its effect on fitness; hence, variable characters
are more likely to differ between populations as they are
adaptively neutral. Divergence between populations in

Page 118

variable characters occurs in response to directional selec-
tion (KLUGE & KERFOOT, 1973) or to environmental ef-
fects (SOKAL, 1976, 1978).

Recently ROHLF et al. (1983) reported the “Kluge-Ker-
foot phenomenon” to be a statistical artifact, a result of
calculating coefficients of variation for characters with dif-
ferent units, distributions, and sampling error. The pres-
ent study, using multigroup PCA, supports Kluge and
Kerfoot’s premise without using coefficients of variation.

In reference to the biology of Cypraea caputserpentis,
the existence of the Kluge-Kerfoot phenomenon suggests
that intrapopulation variations in size, callosity, and num-
ber of basal teeth are adaptively neutral characteristics
that have been subject to directional selection and/or dif-
ferent environments between populations, producing geo-
graphic variation. This hypothesis can be tested by mea-
suring natural selection within several populations
(HALDANE, 1954; LANDE & ARNOLD, 1983) and by un-
dertaking a reciprocal transplant study. The elucidation
of mechanisms relating intra- and inter-population vari-
ation in C. caputserpentis, coupled with an analysis of
geographic variation in larval dispersal characteristics,
could provide valuable information concerning the devel-
opment of geographic variation, and the subsequent evo-
lution of species.

ACKNOWLEDGMENTS

I am indebted to a multitude of people who helped in
various aspects of this project. P. Colman, E. Dunlap, R.
Faniel, T. Gosliner, E. A. Kay, W. Old, V. Perrault, R.
Robertson, J. Rosewater, J. Steinbeck, L. Thomas, R.
Thomas, F. Wells, J. Wenno, and M. Young generously
supplied samples as well as numerous helpful comments.
Special thanks go to D. Behrens and personnel at the
Pacific Gas and Electric Company Bioassay Laboratory,
Diablo Canyon, California, for enormous technical sup-
port. I would also like to thank my wife, Allison, for
valuable help and understanding during the endless hours
I spent measuring shells. This paper is largely a product
of critical reviews of drafts of the manuscript by D. Beh-
rens, G. Brenchley, P. Lebednik, R. Pimentel, H. Rehder,
J. Steinbeck, and two anonymous reviewers. This paper
began as a 1981 class project for Morphometrics (Bio 543)
taught by R. Pimentel and R. Riggins-Pimentel at Cali-
fornia Polytechnic State University, San Luis Obispo.

LITERATURE CITED

ALLAN, J. 1958. Cowry shells of world seas. Georgian House:
Melbourne.

BaILey-Brock, J. H. 1976. Habitats of tubicolous polychaetes
from the Hawaiian Islands and Johnston Atoll. Pacific Sci.
30:69-81.

Brock, R. E. 1980. A statistical study of Cypraea tigris in the
central Pacific. Veliger 22(2):166-170.

The Veliger, Vol. 27, No. 2

BUGGELN, R. G. & R. S. TsupA. 1966. A preliminary algal
flora from selected habitats on Johnston Atoll. Hawaii Inst.
Mar. Biol. Tech. Rept. 9:1-29.

Burcess, C.M. 1970. The living cowries. A. S. Barnes: Cran-
bury, New Jersey.

CaALHOON, R. E. & D. L. JAMESON. 1970. Canonical corre-
lation between variation in weather and variation in size in
the Pacific tree frog, Hyla regilla, in Southern California.
Copeia 1:124-134.

CaTE, C. N. 1964. West Australian cowries. Veliger 7(1):7-
7B)

CaTE, C. N. 1969. The eastern Pacific cowries. Veliger 12(1):
103-119.

CROTHERS, J. H. 1982. Shell shape variation in dogwhelks
(Nucella lapillus [L.]) from the west coast of Scotland. Biol.
J. Linn. Soc. 17:319-342.

Dixon, W. J. & M. B. BRowN (EDs.). 1979. Biomedical com-
puter programs, P-series. Univ. of Calif. Press: Berkeley.

DoszHANKsy, TH., F. J. AYALA, G. L. STEBBINS & J. W. VAL-
ENTINE. 1977. Evolution. W. H. Freeman & Co.: San
Francisco.

Eser, L., J. F. T. Saur & O. E. SETTE! 1968. Monthly mean
charts sea surface temperature north Pacific ocean 1949-
62. Bureau Comm. Fish. Ocean Res. Lab., Stanford, Cali-
fornia.

EDMONDSON, C. H., W. K. FISHER, H. L. CLARK, A. L. TREAD-
WELL & J. A. CUSHMAN. 1925. Marine zoology of the
tropical central Pacific. Bull. Bernice P. Bishop Mus. 27:
1-148.

FANIEL, R. H. 1978. Consider Cypraea caputserpentis. Hawai-
ian Shell News 26(8):3.

Forn, T. C. 1972. Ecological influences on the size of Cypraea
tagris L., 1758, in the Pacific. Proc. Malacol. Soc. Lond. 40:
211-218.

Fon, T. C. 1976. Plate tectonics and the biogeography of the
Cypraeidae (Mollusca: Gastropoda). J. Biogeography 3:19-
34.

FRANK, P. W. 1975. Latitudinal variation in the life history
features of the black turban snail Tegula funebralis (Proso-
branchia: Trochidae). Mar. Biol. 31:181-192.

GosLINE, W. A. 1955. The inshore fish fauna of Johnston
Island, a central Pacific atoll. Pacific Sci. 9:442-480.

GOuLD, S. J. & R. F. JOHNSTON. 1972. Geographic variation.
Ann. Rev. Ecol. Syst. 3:457-498.

GRIFFITHS, R. J. 1958. Subspeciation in two species of Cy-
praeidae. Proc. Malacol. Soc. Lond. 33(5):176-185.

HALDANE, J. B. S. 1954. The measurement of natural selec-
tion. Prox. IX Intl. Cong. Genet. 1:480-487.

HELLER, J. 1976. The effects of exposure and predation on
shells of two British winkles. J. Zool., Lond. 179:201-213.

Kay, E. A. 1957. The systematics of the Cypraeidae as elu-
cidated by a study of Cypraea caputserpentis and related forms.
Doctoral Thesis, Univ. of Hawaii.

Kay, E. A. 1960. The functional morphology of Cypraea ca-
putserpentis L. and an interpretation of the relationships
among the Cypraeacea. Int. Revue Ges. Hydrobiol. 45(2):
175-196.

Kay, E. A. 1961a. On Cypraea tigris schilderiana Cate. Veliger
4(1):36-40.

Kay, E. A. 1961b. A zoogeographic analysis of species of Cy-
praea in the Hawaiian Islands. Proc. Malacol. Soc. Lond.
34:185-199.

Kay, E. A. 1967. The composition and relationships of marine
molluscan fauna of the Hawaiian Islands. Venus 25:94-
104.

B. N. Tissot, 1984

Kay, E. A. 1979. Hawaiian marine shells. Bernice P. Bishop
Mus. Special Publ. 64(4).

Kenny, R. 1983. Growth characteristics of intertidal limpets
in relation to temperature trends. Pacific Sci. 37(1):37-44.

KiuGE, A. G. & W. C. Kerroor. 1973. The predictability
and regularity of character divergence. Amer. Natur. 107:
426-442.

LANDE, R. & S. J. ARNOLD. 1983. The measurement of nat-
ural selection on correlated characters. Evolution 37(6):1210-
1226.

LINNAEUS, C. 1758. Systema naturae per regna tria naturae.
Editio decima, reformata. Stockholm, 10th edition. 718 pp.

LIVERSIDGE, M. J. H. 1968. On the distribution of Cypraea
(Erosaria) marginalis along the east coast of Africa. J. Conch.
26:229-236.

Marcus, L. F. & J. H. VANDERMEER. 1966. Regional trends
in geographic variation. Syst. Zool. 15:1-13.

MatTHER, P. M. 1976. Computational methods of multivariate
analysis in physical geography. John Wiley & Sons: Lon-
don.

Murpuy, K. M. 1972. A morphometric analysis of two species
of Batrachoseps. Masters Thesis, Calif. Polytechnic State
Univ., San Luis Obispo.

Orr, V. 1959. A bionomic shell study of Monetaria annulus
(Gastropoda: Cypraeidae) from Zanzibar. Notulae Naturae
313:1-11.

PHILLIPS, B. F., N. A. CAMPBELL & B. R. WILSON. 1973. A
multivariate study of geographic variation in the whelk Di-
cathais. J. Exp. Mar. Biol. Ecol. 11(1):27-69.

PIMENTEL, R. A. 1979. Morphometrics, the multivariate anal-
ysis of biological data. Kendall-Hunt: Dubuque, Iowa.
PIMENTEL, R. A. 1981. A comparative study of data and or-
dination techniques based on a hybrid swarm of sand ver-

benas (Abronia Juss.). Syst. Zool. 30(3):250-267.

REHDER, H. A. 1980. Marine mollusks of Easter Island (Isla
de Pascua) and Sala y Gomez. Smith. Contrib. Sci. 289:1-
167.

RENAUD, M. L. 1976. Observations on the behavior and shell
types of Cypraea moneta (Mollusca, Gastropoda) at Enewe-
tak, Marshall Islands. Pacific Sci. 30:147-158.

ROHLF, F. J. 1972. An empirical comparison of three ordi-
nation techniques in numerical taxonomy. Syst. Zool. 21:
271-280.

ROHLF, F. J., A. J. GILMARTIN & G. Hart. 1983. The Kluge-
Kerfoot phenomenon—a statistical artifact. Evolution 37(1):
180-202.

RUMMEL, R. J. 1970. Applied factor analysis. Northwestern
Univ. Press: Evanston, I]linois.

SCHILDER, F. A. 1927. Revision der Cypraeacea. Archiv Na-
turgeschichte A(10):1-165.

SCHILDER, F. A. 1961. A statistical study in cowries: the size
of Mauritia arabica (Linnaeus). Veliger 4(1):15-17.

SCHILDER, F. A. 1962. The size of Cypraea tigris Linnaeus.
Cowry 1(3):43-44.

SCHILDER, F. A. 1967. Intraspecific evolution in Blasicrura
interrupta (Gray). Veliger 9(3):292-297.

SCHILDER, F. A. 1969. Zoogeographical studies on living cow-
ries. Veliger 11(4):367-377.

SCHILDER, F. A. & M. SCHILDER. 1938-1939. Prodrome of a
monograph on living Cypraeidae. Proc. Malacol. Lond.
23(3/4):119-231.

SCHILDER, F. A. & M. SCHILDER. 1961. Sexual differences in
cowries. Proc. Malacol. Soc. Lond. 34:207-209.

Page 119

SCHILDER, F. A. & M. SCHILDER. 1968. Studies on popula-
tions of the cowrie Erronea errones (Linnaeus). Veliger 11(2):
109-116.

SCHILDER, M. & F. A. SCHILDER. 1967. Studies on east Aus-
tralian cowries. Veliger 10(2):103-110.

SCHILDER, M. & F. A. SCHILDER. 1971. A catalogue of living
and fossil cowries. Mem. Inst. Royal Sci. Nat. Belgique 2nd
series, 86:1-214.

SNEATH, P. H. A. & R. R. SOKAL. 1973. Numerical taxonomy,
the principles and practice of numerical classification. W.
H. Freeman & Co.: San Francisco.

SokaL, R. R. 1976. The Kluge-Kerfoot phenomenon reex-
amined. Amer. Natur. 110(976):1077-1091.

SOKAL, R. R. 1978. Population differentiation: something new
or more of the same? Pp. 215-239. In: P. F. Brussard (ed.),
Ecological genetics: the interface. Springer-Verlag: New
York.

SokaL, R. R. & F. J. ROHLF. 1969. Biometry, the principles
and practice of statistics in biological research. W. H. Free-
man & Company: San Francisco.

STAIGER, H. 1957. Genetical and morphological variation in
Purpura lapillus with respect to local and regional differ-
entiation of population groups. Annee Biol. 33:251-258.

STRUHSAKER, J. W. 1968. Selection mechanisms associated
with intraspecific shell variation in Littorina picta (Proso-
branchia: Mesogastropoda). Evolution 22:459-480.

SUMMERS, R. 1975. Cypraea englerti, C. caputdraconis and their
relatives. Hawaiian Shell News 23(1):8.

SveRDRUP, H. U., M. W. JOHNSON & R. H. FLEMING. 1942.
The oceans, their physics, chemistry, and general biology.
Prentice-Hall: New York.

Taybor, J. & J. G. WALLS. 1975. Cowries. T. F. H. Publ.
Inc.: Neptune City, New Jersey.

TuHorpe, R. S. 1976. Biometric analysis of geographic varia-
tion and racial affinities. Biol. Rev. 51:407-452.

Tissot, B. N. 1981. Geographic variation in Cypraea caput-
serpentis and an interpretation of its relationship with Cy-
praea caputdraconis. Ann. Rept. West. Soc. Malacol. 14.

Tissot, B. N. & J. R. STEINBECK. 1983. Microgeographic
variation in Collisella digitalis: the use of shell morphomet-
rics as a possible indicator of thermal impact. Chapter 10.
In: D. W. Behrens (ed.), Environmental investigations at
Diablo Canyon, 1982. Dept. Engr. Res., Pacific Gas &
Electric Comp.: San Ramon, California.

UNITED STATES NAvy HyDROGRAPHIC OFFICE. 1944. World
atlas of sea surface temperatures. Hydrographic Office Publ.
225, Washington, D.C.

VAN VALEN, L. 1965. Morphological variation and width of
ecological niche. Amer. Natur. 908:377-390.

VERMEIJ, G. J. 1978. Biogeography and adaptation, patterns
of marine life. Harvard Univ. Press: Cambridge, Massa-
chusetts.

Witson, B. R. & R. SUMMERS. 1966. Variation in the Zoila
friendi (Gray) species complex (Gastropoda: Cypraeidae) in
South-Western Australia. J. Malacol. Austrl. 1(9):3-24.

Wyrtkl, K., E. BENNETT & D. RocHForD. 1971. Oceano-
graphic atlas of the international Indian Ocean expedition.
Natl. Sci. Found.: Washington, D.C.

ZINSMEISTER, W. J. & W. K. Emerson. 1979. The role of
passive dispersal in the distribution of hemipelagic inverte-
brates, with examples from the tropical Pacific ocean. Ve-
liger 22(1):32-40.

The Veliger 27(2):120-125 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

Seasonal Variation in Biochemical
Composition of the Fresh-water Pond Snail
Vieiparus bengalensis Linnaeus
by

Pak; GUPARA

Department of Zoology, K.L.D.A.V. College,
Roorkee 247667, India

AND

V.S. DURVE

Department of Limnology and Fisheries, University of Udaipur,
Udaipur 313001, India

Abstract. The seasonal biochemical analysis of the soft body tissues of the fresh-water pond snail
Vieiparus bengalensis Linnaeus was conducted for both sexes to determine water, ash, glycogen, protein,
lipids, cholesterol, and total energy values. Water constituted the bulk of the tissue, fluctuating between
79.14 and 83.83%; this variation was related to breeding and environmental factors. Ash content did
not exhibit any relation to the reproductive cycle and varied between 125.43 and 212.93 mg/g. Glycogen
levels depended on feeding and the reproductive cycle of the snail, as glycogen is utilized in gamete
formation; these values varied between 197.57 and 389.37 mg/g. Protein formed the bulk of organic
constituents, and values between 341.54 and 581.48 mg/g were recorded. Lipids fluctuated between
34.45 and 121.92 mg/g, and exhibited significantly different levels between the two sexes. Cholesterol
levels exhibited a confusing situation; they did not show a definite trend and fluctuated from 120.00 to
221.48 mg/g. The total energy values differed significantly both between the sexes and between seasons;
values from 4.514 to 8.568 kcal/g were recorded.

INTRODUCTION

SEASONAL VARIATIONS in biochemical composition are in-
variably cyclical in nature and closely follow the physio-
logical activities of the animal. Because many mollusks
have food value, biochemical studies on them have as-
sumed great importance. These studies on mollusks, apart
from providing valuable information on their constitution,
also give insights into their body physiology during dif-
ferent seasons of the year.

Biochemical analyses of a number of mollusks have been
made by many workers. Several have investigated the bio-
chemical composition of gastropods and related them to
the animals’ reproductive cycles and environmental fac-
tors: MEENAKSHI (1956) for Pila, EMERSON (1965) for
prosobranch snails, WEBBER (1970) for Haliotis, RAO et

al. (1972) and CHATTERJEE & GHOSE (1973) for Vivip-
arus and Acrosloma, STICKLE (1975), and LAMBERT &
DEHNEL (1974) for Thazs.

The seasonal biochemical composition of Viviparus ben-
galensis has not been studied in detail. The present work
deals with the monthly biochemical variations in water,
ash, glycogen, protein, lipid, cholesterol, and total energy
values in relation to this snail’s reproductive cycle.

MATERIALS anp METHODS

Specimens of the snail Viviparus bengalensis were collected
from a pond once a month (preferably in the second week)
from January 1979 to March 1980. They were placed in
a well-aerated glass aquarium in the laboratory and sort-
ed by sex. Thirty to forty healthy snails of each sex were

P. K. Gupta & V. S. Durve, 1984

sacrificed each month for the study. All of the weighings
were done on a microanalytical balance to the nearest
0.001 mg. Except for water content, all the tests were
performed on dry tissue, and the results are presented on
a dry tissue weight basis. Each sample was analyzed in
triplicate or quadruplicate.

To determine the percentage of water, after breaking
open the shell the soft body tissue was dried in an oven
at 60°C to a constant weight. The difference between pre-
-and post-dried tissue weight was taken as its water con-
tent. Ash contents were determined by ashing the dried,
powdered tissue in a muffle furnace at 600°C for 6 h.
Glycogen was estimated by the method of SEIFTER et al.
(1950), using anthrone as the coloring agent and 1.11 as
the multiplying factor. Total proteins were determined by
the folin phenol reagent method (Lowry et al., 1951) with
bovine albumin Fraction IV as the standard. Soxlet ex-
tractors of 100-mL capacity were utilized for extracting
the lipid from the tissue; petroleum ether was the solvent.
The method of PEARSON et al. (1954) was adopted for the
estimation of cholesterol using paratoluene sulfonic acid
as the coloring agent. Total energy was determined by
burning a known amount of dried and powdered tissue in
a bomb calorimeter following LEITH’s (1968) method.

The water content is presented as percentage wet weight,
the energy values as kcal/g dry weight, and the remaining
biochemicals as mg/g dry weight. All of the spectropho-
tometric readings were carried out on a Systronic MK
105 spectrophotometer. The data were subject to Student’s
t-test for the determination of significance. Standard de-
viation was calculated by the formula of SNEDECOR &
CocHRAN (1967). Significance of the means was calculat-
ed by t-tests (STEEL & TorRIE, 1960) using a formula
appropriate for unpaired observations and unequal vari-
ances. Significance levels were set at 0.05 and 0.001%.

RESULTS

Water constituted the bulk of the total wet weight of the
body tissue and varied between 79.14 and 83.83%. In
males the highest and lowest levels were recorded in De-
cember (83.83%) and May 1979 (80.69%) respectively,
whereas in females these were in January 1979 (82.28%)
and December (79.14%). Water content differed signifi-
cantly between sexes of the snail (P < 0.05) in the months
of February, April, May, June, July, and August of 1979,
and in March 1980; highly significant differences were
recorded in September, October, November, and Decem-
ber of 1979, and in February 1980 (P < 0.001). In Jan-
uary and March of 1979, and in January 1980, the dif-
ference was nonsignificant (Table 1).

Ash represents the total inorganic contents of the tissue.
In males, after recording a peak value of 212.93 mg/g in
February 1979, ash declined sharply to its lowest level of
125.43 mg/g in July. In females, ash exhibited its peak
level of 194.28 mg/g in January 1979. This peak was
followed by a decrease that touched the lowest level of

Page 121

131.36 mg/g (with the exception of April when suddenly
it rose). However, January 1980 yielded a maximum val-
ue of 200.51 mg/g. February, March, June, July, Sep-
tember, October, and November of 1979, and February
and March of 1980, yielded significant levels of variation,
and the difference was highly significant in January 1980
(Table 1).

Glycogen levels were correlated with the reproductive
cycle of the snail. During the prespawning and spawning
months (January to April) a decrease in glycogen levels
was recorded in males. In August, which also happens to
be a prespawning month, glycogen reached the highest
value of 369.01 mg/g. In the peak spawning month of
October, it fell to the lowest level of 197.57 mg/g. In
contrast to males, females showed increases in glycogen
content from January to March 1979 (the later posting
the highest value of 368.11 mg/g). During spawning and
postspawning months fom April to June, glycogen levels
declined rapidly, reaching the lowest value of 251.49 mg/g
in June. December and January registered declines as the
animal underwent hibernation. The prespawning month
of March 1980 recorded a steep rise to 389.37 mg/g.
Significant differences between the sexes were observed
from January to April, August, September, and Novem-
ber of 1979, and February of 1980; October and Decem-
ber yielded highly significant differences (Table 1; Figure
1).

Protein formed the bulk of the organic content of the
tissue in both sexes. The males registered the maximum
level of 581.48 mg/g in October and the lowest level of
416.32 mg/g in January 1979. Females recorded their
highest protein values in June (576.93 mg/g) and lowest
in February (1979). April, September, and October of
1979, and February of 1980, exhibited highly significant
differences in protein content between the sexes; for Jan-
uary, June, and July of 1979, these differences were non-
significant, and for the rest of the period of study they
were significant (Table 1).

Like glycogen, lipids also showed seasonal variation in
relation to the breeding cycle of the snail. Males recorded
the lowest values of 44.56 and 44.86 mg/g in February
and March respectively, and the highest value of 77.87
mg/g in November, which is the month of hibernation.
Females exhibited an interesting pattern. After recording
their highest value of 121.91 mg/g in February 1979,
glycogen levels in females declined rapidly and touched
the lowest level of 34.45 mg/g in June. There were highly
significant differences between the sexes in a majority of
the months of study, except for May, July, August, and
December of 1979, and March of 1980, when differences
were significant (Table 2; Figure 2).

Cholesterol forms an important constituent of lipids and
plays a significant role in metabolic processes. The males
recorded their lowest values of 134.81 mg/g in March
1979 and their highest in September (221.48 mg/g). In
females, after recording the lowest value of 118.51 mg/g
in January 1979, a gradual rise in cholesterol content was

Page 122

The Veliger, Vol, 275 Now

Table 1

Monthly variations in water percentage, ash, glycogen, and protein content, reported as mean + standard deviation and
t-values, in the soft tissues of male and female Viviparus bengalensis L.

Water percentage (wet wt.)
Month P s

and year Male

Female (-value Male

Jan. ’79 81.71 82.28 0.60 NS 192.98 194.28 0.10 NS

+0.79 +0.74 +3.87 +1.90
Feb779 | 81.98. 180163) 2:21 212.93 171.65 1.48*
+0.67 +£0.57 +416 +4.90
Mar.’79 81.59 80.87 0.48NS 200.53 163.35 1.49*
+1.31 +0.50 +3.68 +4.88
Apr.’79 81.61. 80.61 -0.99* 185.74 202.06 0.61 NS
+0.93 +0.52 +2.95 +5.45
May’79 80.69 79.79 1.05* 134.22 131.36 0.19 NS
+0.72 +0.72 +244 +3.69
Jun.’79 82.54 79.80 6.55** 127.70 140.69 1.45*
+0.51 +0.47 +2.25 +2.79
Julee79) 82376. = se226u a1" 125.43 154.15 2.49*
+0.52 +0.46 42.01 +3.37
Auee79 Bsa | 81199) 3.80% * 130.48 134.55 0.39 NS
+0.50 +0.50 +0.89 +3.52
Sepi779 6278 8154" slo7** 136.48 154.56 2.73**
+0.38 +0.14 +160 +2.48
Oct.’79 81.99 79.89 3.22** 127.77 149.49 5.46**
+0.82 +0.38 +143 +1.87
Nov.’79 82.44 79.72 4.86** 141.88 159.69 1.32*
+0.36 +0.70 42.37 +3.67
Dec.’79 83.83 79.14 7.88** 162.70 169.46 0.65 NS
+0.73 +0.37 +3.07 +2.25
Jan.°80 81.24 81.28 0.06NS 180.87 200.51 3.54**
+0.85 +0.38 +1.88 +2.00
Feb.’80 81.38 79.93 3.44** 175.08 183.37 0.83
+0.53 +0.46 +2.72 +2.42
Mar.’80 81.86 81.27 0.79* 159.41 141.01 0.73*
+0.52 +0.79 +1.18 +6.03

Ash (mg/g dry weight)

Female (-value

Glycogen (mg/g dry weight) Protein (mg/g dry weight)

NS Non-significant.
* Significant (P < 0.05).
** Highly significant (P < 0.001).

observed, and a maximum value of 197.98 mg/g was
reached in June. Highly significant levels of cholesterol
were observed in the months of September, October, and
November of 1979, and February of 1980; they were not
significant in March, April, and August of 1979 and Jan-
uary of 1980, and significant for the remaining months of
study (Table 2).

Males exhibited their lowest and highest total energy
values in December (5.470 kcal/g) and March of 1979
(8.563 kcal/g) respectively. Females recorded the lowest
energy value in March of 1979 (4.514 kcal/g) and the
highest value in August (7.441 keal/g). Highly significant
differences were observed for these values for all of the
months with the sole exception of February 1980, when
the difference was significant, and January 1980, when it
was not significant (Table 2).

Male Female (-value Male Female t-value
344.32 319.73 0.80* 416.32 413.56 0.06 NS
+6129) E2260 st aC, Sass et 310)
3112 7.8) 365122) 204% 424.74 341.54 2.51*
23/520) V=EA"86 = 51 OO =ts4103
289.19 368.11 2.00* 463.18 361.60 1.46*
1/64) =E7.08 +6.28 +8.06
239 3 35a 24s HOA 4B Gil - 7/5
AT 4 5579 aEilesX) a 5).335}
269.19 288.24 0.51 NS 516.52 526.74 0.98*
+5.04 +4.99 ar)5)6). sei -(4il
241.62 251.49 0.36 NS 563.47 576.93 0.38 NS
+4.09 +4.66 +6.96 ar 2S)
2M) | 266413 OMENS 538.75 566.80 0.34NS
+6.15 +1.66 +9.88 +4.72
369.01 311.46 1.04* 446.30 502.26 1.81*
still = 83.9) +4.88 + 4.34
281.08 268.47 1.05* ADN22) 52103 Oma 45 a
2) 08 ie 932 SEAVAY] ete Ge AS
197-57 | 305313) 402% Bol AGA 5.35
+3.60 +4.68 SRC are sy
282.97 358.38 -2:32* 514.96 460.82 2.77*
+6.46 +1.27 BES\eY) ae 3.6
D545 9 333 "5 i St 82 ee 53163 64 2p ee ler
+4.03 Ee Hoy) +4.96 a2 7/559)
283.92 300.54 0.33 NS 445.19 42274 i 13*
+ 4.99 sheath) +2.69 +4.47
381.62 327.30 1.76* 430192 401.76 3:26**
+4.19 +4.85 ane) iS) +1.76
375.41 389.37 0.24NS 414.46 383.16 1.97*
+4.27 +7.66 +3.84 +3.01
DISCUSSION

Reproductive cycle and seasonal environmental changes
are two main factors influencing the biochemical synthesis
and utilization of metabolites. Similarly, changes in abiot-
ic and biotic factors, such as temperature, pH, salinity,
humidity, aridity, and availability and type of food in the
aquatic ecosystem, are largely responsible for the bio-
chemical variations in the body tissues of the animals liv-
ing therein.

In the case of Viviparus bengalensis, the biochemical
variations have been found to be interlinked with its pro-
longed breeding activity and environmental fluctuations.
These snails were collected from a pond with a maximum
depth of 2.4 m. The water temperature recorded was 19°C
in December, 27°C in April, 32°C in June, and 30°C in
September. The pH of the pond water ranged from 7.8

Page 123

P. K. Gupta & V. S. Durve, 1984

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Mave ee
80 5 4Cm=2mg/q
ere
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att Hi

LIPID CONTENTS (mg/g)

te
(iat i) .Urer trem aot ay
1979 MONTHS 1980
Figure 2

Monthly variations, with standard deviations, in lipid content of
soft body tissue of Viviparus bengalensis. *Denotes months of
intensive breeding activity.

winter months in both the sexes. Similar observations were
made by SPECTOR (1956) for clams, oysters, and scallops,
and FRAGA (1956) for Mytilus edulis. Our results are close
to those reported by VENKATARAMAN & CHar!I (1951) and
DurveE & BAL (1961) for Ostrea madrasensis, Meretrix
casta, and Crassostrea gryphoides. However, the difference
between the present results and those of LUTGARDs (1950)
and Rosas (1950) may be due to differences in species,
environment, geography, and water quality.

Variations in glycogen levels are dependent on feeding
and reproductive activities of the snail. The decline in
glycogen level in males from January to May and in fe-
males from February to July is likely due to its utilization
for gametogenesis; peak breeding activity occurs in April.
This decline in glycogen level was followed by an increase
until August due to postspawning increases in feeding
activity. The subsequent decline in September (males) and
October (females) is correlated with reproduction: in fe-
males, the developing embryos and young consume energy
in the form of glycogen. Thereafter, a gradual rise in
glycogen level is due to inactivity during hibernation, when
catabolic activities are at their lowest. Similar views were
expressed by BARRY & Munpbay (1959), BLACKMORE
(1969), WEBBER (1970), and MuLey (1975) concerning
similar studies of Patella vulgata, Haliotis cracherodii, and
Melania scabra. In the present study, except for January,
July, and May, the males had lower glycogen contents
than the females. CHATTERJEE & GHOSE (1973) and

The! Veliger; Vole 27a Now,

LAMBERT & DEHNEL (1974) correlated this higher gly-
cogen in female Thais lamellosa with the number of eggs
produced, as it provides raw material for their formation.
Rao et al. (1972) reported very low glycogen contents
during aestivation in Viviparus bengalensis when low ac-
tivity levels and decreasing metabolic rates are recorded.

The monthly variations in protein content in the snail
had no correlation with the reproductive cycle and might
depend upon nutrient conditions and environmental vari-
ables. This view was also shared by NAGABHUSHANAM &
MANE (1975), but is contrary to that expressed by STICK-
LE (1975). The results of the present investigation closely
resemble those reported by GIESE (1969) for Tivella stul-
torum, but differ from findings of NAGABHUSHANAM &
MANE (1975).

In the present study, an increase in lipid content in
males from February to May was followed by a decline
during spawning months up to July, with another in-
crease until November. The decrease in December was
probably due to winter dormancy when there is suspen-
sion or reduction in feeding activity, and lipids are con-
sumed for energy. In females, there is a decrease from
February to June that is due to lipid utilization for breed-
ing activities, especially the formation of egg capsules in
the uterus. From July, lipid levels started increasing dur-
ing the prespawning period, fell in the spawning months
of September and October, and rose again in subsequent
months (postspawning period). The lipid values ranged
between 3.44 and 12.99% of dry body weight which, ac-
cording to GIESE (1969) and MULEy (1975), is an appro-
priate value. In the present investigation, no relationship
between sex and the amount of stored fats could be estab-
lished.

Cholesterol presented a confusing situation. According
to VooGcT (1971, 1972) this chemical is the main constit-
uent of lipids in Viviparus histricus and other species of
Viviparus. In the present study, it exhibited a trend in-
dependent from that of other lipids. During the major
period of study, males exhibited higher values than fe-
males. But during the spawning and postspawning months
of March to August, females showed higher values than
males. The situation was reversed, however, during the
second spawning and postspawning stages (September to
December) when males exhibited higher values. This sug-
gested that there may be some relationship between cho-
lesterol level and gametogenesis. This, however, requires
further investigation.

Because cholesterol was found at high levels and is a
principal component of sterols, it could possibly be rich
in provitamin D, as suggested by VooGT (1972) for oys-
ters. As such, it could form a vitamin-D rich food for other
animals. This also requires further study to investigate
the complex composition of sterols in this snail.

Male snails recorded higher energy values during the
spawning months of March-April and September—Octo-
ber, whereas in females, energy values declined during
this period. In males, a decreasing pattern of energy values

P. K. Gupta & V. S. Durve, 1984

was witnessed in postspawning months (June to August),
whereas in females an increasing trend was shown. In the
winter month of December, when all metabolic activities
decreased considerably, females recorded higher energy
values (6.066 kcal/g) than the males (5.470 kcal/g). The
total energy values of Viviparus bengalensis suggest high
nutritive value of its soft body tissues.

According to GIESE (1969), mollusks lack discrete nu-
trient storage depots, such as the vertebrate liver, the sub-
dermal and ornamental adipose tissues of mammals, and
the fat bodies of lower invertebrates. Thus, nutrient stor-
age occurs primarily through the production of new cel-
lular elements. Seasonal shifts in protein, fats, and gly-
cogen are merely reflections of their relative rates of
synthesis and degradation within the body and are often
meaningless with respect to seasonal shifts in their con-
tents (STICKLE, 1975). With regard to the biochemical
changes in Viviparus bengalensis, we conclude that these
are related to its reproductive cycles and seasonal envi-
ronmental variations. This view is in agreement with the
findings of MULEy (1975), VENKATARAMAN & CHARI
(1951), and DuURVE & BAL (1961) for Melania scabra,
Ostrea madrasensis, Acrosloma variata, and Crassostrea gry-
phoides. As is apparent from the results of this biochemical
analysis, the soft body tissues of V. bengalensis have a
glycogen economy similar to that of lamellibranchs.

ACKNOWLEDGMENTS

The senior author gratefully acknowledges the finance
assistance provided by University Grants Commission,
New Delhi.

LITERATURE CITED

Barry, R. & K. A. Munpay. 1959. Carbohydrate levels in
Patella. J. Mar. Biol. Ass. U.K. 38:81-95.

BLACKMORE, D. T. 1969. Studies on Patella vulgata. 1. Growth,
reproduction and zonal distribution. J. Exp. Mar. Biol. Ecol.
3(3):213-245.

CaMPION, M. 1961. The structure and function of cutaneous
glands in Helix aspersa. Quart. J. Microsc. Sci. 102:195-
216.

CHATTERJEE, B. & K. G. GHOSE. 1973. Seasonal variation in
stored glycogen and lipid in the digestive gland and genital
organs of two freshwater prosobranchs, Viviparus bengalen-
sis and Acrosloma variata. Proc. Malac. Soc. Lond. 40:407-
412.

Durve, V. S. & D. B. BAL. 1961. Studies on the chemical
composition of the oyster, Crassostrea gryphoides. J. Zool.
Soc. India 13:70-77.

EMERSON, D. N. 1965. Summer polysaccharide content in sev-
en species of west coast intertidal prosobranch snails. Veli-
ger 8:62-66.

FRAGA, I. F. 1956. Seasonal variation in the biochemical com-
position of the mussel, Mytilus edulis. Consejo Super. Invest.
Cient. Patronato Juan de la Cierva Invest. Pesquera 4:109.

Fuji, A. 1957. Growth and breeding season of the brackish
water bivalve, Corbicula japonicum, in Zyason Gata inlet.
Bull. Fac. Fish. Hokkaido Univ. 8(3):178.

Page 125

GigsE, A. C. 1966. Lipids in the economy of invertebrates.
Physiol. Rev. 46:244-298.

GigEsE, A. C. 1969. A new approach to the biochemical com-
position of the molluscan body. Oceanogr. Mar. Biol. Ann.
Rev. 7:175-229.

LAMBERT, P. & P. A. DEHNEL. 1974. Seasonal variations in bio-
chemical competition during the reproductive cycle of the
intertidal gastropod, Thais lamellosa Gmelin (Gastropoda,
Prosobranchia). Can. J. Zool. 52(3):305-318.

Lowry, O., N. J. ROSEBROUGH, A. L. FARR & R. J. RANDALL.
1951. Protein measurement with the folin phenol reagent.
J. Biol. Chem. 193:265-271.

LEITH, H. 1968. The measurement of calorific value of bio-
logical material and determination of ecological efficiency in
functioning of terrestrial ecosystems at primary production
level. Proc. Copenhagen Sym. Paris UNESCO, pp. 233-
242.

Lutcarps, B. R. L. 1950. Chemical and nutritional analysis
of Fissurella maxima. Anales Facultad Farm. y Bioquim.
Univ. Nacl. Mayor San Marcos, pp. 155-159.

MEENAKSHI, V. R. 1956. Seasonal variation in the glycogen
and fat content in the apple snail, Pila virens (Lamarck).
Proc. Zool. Soc. India 8:1-98.

MuLey, E. V. 1975. Seasonal variations in biochemical com-
position of the freshwater prosobranch, Melania scabra. Riv.
Idrobiol. 14(3):199-208.

NAGABHUSHANAM, R. & A. B. KULKARNI. 1971. Reproductive
biology of the land slug, Laevicules alta. Rivista di Biologia
64:15-22.

NAGABHUSHANAM, R. & V. H. MANE. 1975. Seasonal varia-
tion in the biochemical composition of the clam, Katelysia
opima. Rivista di Biologia 68(4):279-302.

Rao, B. D., M. C. VENKATASUBBAIAH, R. S. REDpDy, A. N.
Raju, P. V. Rao & K. S. Swami. 1972. Metabolism of
brooding young from aestivating adults of the banded pond
snail Viviparus bengalensis. Malacologia 11(2):281-286.

Rosas, H. E. D. 1950. Chemical and nutritional analysis of
Concholepas concholepas. Anales Facultad Farm. y Bioquim.
Univ. Nacl. Mayor San Marcos 1:115-119.

SEIFTER, S. S., S. DayTon, B. Novoc & E. MUTWYLER. 1950.
The estimation of glycogen with the anthrone reagent. Arch.
Biochem. 25:191-200.

SNEDECOR, C. W. & W. G. COCHRAN. 1967. Statistical meth-
ods. 6th ed. Iowa State University Press: Ames, Iowa.
Spector, W. S. 1956. Handbook of biological data. W. B.

Saunders Co.: Philadelphia.

STEEL, R. G. D. & J. H. Torrie. 1960. Principles and pro-
cedures of statistics. McGraw-Hill: New York.

STICKLE, W. B. 1975. The reproductive physiology of the in-
tertidal prosobranch Thazs lamellosa Gmelin. II. Seasonal
changes in the biochemical composition. Biol. Bull. 148:
448-460.

VENKATARAMAN, R. & S. T. CHARI. 1951. Studies on oysters
and clams: biochemical variations. Ind. J. Med. Res. 39(4):
533-541.

VoocT, P. A. 1971. Sterols in some prosobranchs. Arch. Int.
Physiol. Biochem. 79(2):391-400.

VoocT, P. A. 1972. Lipids and sterol components and metab-
olism in Mollusca. Pp. 245-300. In: M. Florkin & B. T.
Scheer (eds.), Chemical zoology. Vol. VII.

WEBBER, H. H. 1970. Changes in the metabolic composition
during the reproductive cycle of the abalone, Haliotis crach-
erodiu (Gastropoda: Prosobranchiata). Physiol. Zool. 43(3):
213-231.

The Veliger 27(2):126-133 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

Gonadal Organization and Gametogenesis in the

Fresh-water Mussel Diplodon chilensis chilensis
(Mollusca: Bivalvia)

by

SANTIAGO PEREDO anp ESPERANZA PARADA

Department of Natural Sciences, Catholic University of Chile-Temuco,
Casilla 15-D, Temuco, Chile

Abstract.

The gonadal organization and cytological characteristics of gametogenesis in the fresh-

water mussel Diplodon chilensis chilensis are described. Although the sexes did not differ macroscopically,
gonadal sections demonstrate the existence of gonochoric individuals in which testis and ovary are
clearly distinct. In both sexes, gonads are ramified organs bearing numerous follicles closely packed
among the intestine coils. Follicles in males contain gametes at different stages of maturation which
can be recognized by their shape, size, and nuclear features. They are organized in clusters of sper-
matogonia, primary and secondary spermatocytes, and spermatids. Spermatozoa are accumulated in
the lumen of follicles. Follicles of the female gonad contain oogonia and oocytes at different stages of
development. Morphological features similar to those described in other fresh-water and marine bivalves
are apparent. In the specimens of the size classes examined, no differences in the gonadal organization
and gametogenesis were observed during the study period.

INTRODUCTION

DUE TO CHILE’s extensive coastline (approximately 4200
km) and the subsequent diversity and abundance of ma-
rine invertebrates, most of the studies about reproduction
and other aspects of the biology of mollusks have been
carried out on marine species, especially those of com-
mercial value. A review of the literature shows that many
aspects of the biology of the fresh-water mollusks inhab-
iting Chile have never been studied. Practically nothing is
known about the reproduction of the fresh-water mussel
Diplodon chilensis chilensis (Gray, 1828) although it is
abundant in rivers and lakes of Chile and ranges from
Arica in the North (18°30’) to the Strait of Magellan in
the southern part of the country (53°). Diplodon chilensis
chilensis is a hardy bivalve that tolerates temperature and
oxygen level changes and possesses a high filtration ca-
pacity (BUSSE, 1970).

Due to the vulnerability of the gonadic tissue to envi-
ronmental contaminants such as organochlorine com-
pounds, pesticides, and heavy metals, the study of the re-
production of Diplodon chilensis chilensis is of importance
in biological monitoring studies. This species may prove
useful as an indicator of environmental changes due to
fresh-water pollution, which in turn may be a source of
pollution of coastal waters. The subsequent negative ef-

fects of such pollutants on littoral communities have been
reported in several studies (KNAUER & MarTIN, 1972;
WILLIAMS & WEISS, 1973; BERGE & HILLEBRAND, 1974;
WoLF, 1975; REIJNDERS, 1980).

The present study analyzes the histology of the gonads
and the cytological characteristics of gametogenesis in Dr-
plodon chilensis chilensis.

MATERIALS anp METHODS

In March 1982, specimens of Diplodon chilensis chilensis
were collected at random from shallow waters of Lake
Villarrica (39°17'S, 72°13'W). The mussels lived at depths
ranging from 20 to 60 cm. The individuals were distrib-
uted in eight sizes grouped in the following classes: S, (16-
25 mm); S, (26-30 mm); S, (31-35 mm); S, (36-40 mm);
S, (41-45 mm); S, (46-50 mm); S, (51-55 mm); and S,
(56-65 mm).

Five individuals were selected at random from each size
class. The sex was determined by gonad smears. The vis-
cera were fixed in aqueous Bouin’s fixative. After embed-
ding in paraffin, serial sections were cut at 7 wm and
stained with hematoxylin and eosin.

The gonadal organization and the cytological charac-
teristics of the germinal and somatic cells of both sexes
were inspected using a light microscope.

S. Peredo & E. Parada, 1984

Page 127

Explanation of Figures 1 to 6

Figure 1. A topographical view of the male gonad of Diplodon
chilensis chilensis. The well delimited follicles (F) occupy the
visceral mass (mesosoma) surrounding the intestine (I). Scanty
interstitial tissue (IT) is present among follicles. x20.

Figure 2. Cell clusters within follicles. A gonoduct (G) is seen
next to the follicles. x50.

Figure 3. Type 1 spermatogonia (SPG 1) in single rows and

type 2 spermatogonia (SPG 2) in clusters in a follicle. The spin-
dle-shaped nucleus (arrow) is from a cell of the follicle wall.
x 500.

Figure 4. Type 1 spermatogonia showing some mitotic figures
(arrows). X 500.

Figures 5, 6. Clusters of primary spermatocytes (SPC 1) show-
ing meiotic prophase configurations (arrows). 200, x 500.

The Veliger, Vol® 27 NioeZ

Explanation of Figures 7 to 12

Figure 7. Clusters of secondary spermatocytes (SPC 2) inter-
spersed with spermatids with rounded nuclei. The nuclei of these
cell types are hardly distinguishable. Next to them are primary
spermatocyte nuclei (SPC 1). x 200.

Figures 8, 9. Clusters of spermatids with rounded nuclei (SPD
1) and elongate nuclei (SPD 2). The acrosomal vacuole can be
seen (arrows). x 200, x 500.

S. Peredo & E. Parada, 1984

RESULTS

Diplodon chilensis chilensis is dioecious, as are the great
majority of bivalves, and sexual dimorphism is absent.

Male Gonad and Germ Cells

The male gonad consists of numerous follicles located
in the visceral mass surrounding the intestinal coils. The
follicles show diversity in shape and size and are delimited
by a thin cellular enveloping membrane (Ancel’s layer)
which may have some connective fibers applied to it. Scanty
interstitial (connective) tissue surrounds the follicles (Fig-
ure 1).

The follicles are crowded with cells at different stages
of spermatogenesis. The cells of particular stages can be
recognized by their shape, size, and nuclear features, and
are arranged in groups or clusters markedly delimited and
located at the periphery of the follicles (Figure 2).

The gonoducts are branched and smaller in diameter
than follicles; a lumen is always present. The walls are
lined with a single row of ciliated columnar cells with
elliptical nuclei. The cytoplasm stains lightly with eosin
(Figure 2).

Spermatogonia: Two types of spermatogonia can be rec-
ognized. Those of the first type are less numerous than
the second and lie in a single row against the membrane
enveloping the follicles. These spermatogonia have large
vesicular nuclei (9.0-10 um) with a conspicuous nucleolus
and loose chromatin (Figure 3). Fibroblast-like cells are
seen next to this type of spermatogonia. The fibroblast-
like cells are in the follicle wall. Their nuclei are spindle
shaped, and the cytoplasm is difficult to visualize (Figure
3). The second type of spermatogonia occurs in clusters
without visible cytoplasm and lies close to, or sometimes
interspersed with, primary spermatocytes. The densely re-
ticulate nuclei possess no nucleoli and are smaller and
stain more heavily than the first type of spermatogonia
(Figure 3). Occasionally, mitotic figures can be seen in
the first type of spermatogonia (Figure 4).

Primary spermatocytes: These cells form numerous and
compact clusters. They have a fine, faintly staining plasma
membrane and a clear, scanty cytoplasm, but these fea-
tures are barely visible in the congested mass of nuclei.
The nuclei vary in appearance as the chromatin assumes
different consistencies and locations within the nucleus.
The chromosomes can be scattered in the nucleus or they
may be polarized at the periphery showing typical figures
of meiotic prophase (Figures 5, 6).

Secondary spermatocytes: Secondary spermatocytes are
seen less commonly than primary spermatocytes. They

—

Figure 10. Sperm in the lumen of a follicle (L). Next to the wall
(W) lie multinucleated spherical bodies (arrows) of atypical
spermatogenesis. x 200.

Figure 11. Gonad smear with spermatozoa. The flagellum can

Page 129

occur in groups generally intermingled with spermatids
forming mixed cell groups (Figure 7). Secondary sper-
matocytes have small, round nuclei (3.0 um) with gran-
ular and heavily staining chromatin.

Spermatids: The nucleus of one type of spermatid is sim-
ilar in shape, size, and staining properties to that of the
secondary spermatocytes (Figure 8). A second type of nu-
cleus can be seen in the spermatid groups. These nuclei
are elongate, stain heavily and homogeneously, and have
a short eosinophilic zone at one end (Figures 8, 9). They
are intermingled with the nuclei of the first type of sper-
matid which show a vacuole similar to the acrosomal
granule (Figure 9).

Spermatozoa: Spermatozoa are formed in the center of
the follicles where they accumulate. The mature sper-
matozoon has an elongate head about 4.0 um long and 1.5
um wide. The chromatin is dense and stains homoge-
neously (Figure 10). Fresh smears of gonad tissue show
flagella four to five times the length of the heads (20-24
um) emerging from the eosinophilic mass at one end of
the sperm heads (Figure 11).

In addition to normal germinal cells, the follicles of
many males also contain numerous multinucleated spher-
ical dark bodies (Figure 12) similar to those described in
Mya arenaria (COE & TURNER, 1938; SHAW, 1965; PorR-
TER, 1974) and Cyprina islandica (LOOSANOFF, 1953). Such
dark bodies are usually closer to the periphery of the fol-
licles than to their center, and contain a variable number
of pycnotic nuclei (from 2 to 10 nuclei); alternatively, they
can be seen as single nuclei (Figure 12).

Female Gonad and Germ Cells

As in males, the female gonad of Diplodon chilensis chi-
lensis is a branched gland embedded in the visceral mass.
Numerous follicles surround the coils of the intestine (Fig-
ure 13). The follicles are irregular in size and shape, and
are limited by a connective tissue wall of variable thick-
ness.

In the follicles, germ cells at different stages of devel-
opment can be recognized by their size, shape, and stain-
ing properties (Figure 13).

Oogonia: Oogonia are observed embedded in the follicle
walls. They are distinguished from the connective tissue
cells by their relatively large size and highly chromatic
nuclei (Figures 14, 15).

Growing oocytes—previtellogenic oocytes: The shape
of the newly formed oocytes may be square, cylindrical,
or hemispherical (Figures 13, 14). They bulge from the

be seen emerging from the eosinophilic end of the sperm head
(midpiece) (arrows). x 500.

Figure 12. Multinucleated spherical bodies (atypical spermato-
genesis). < 500.

Page 130

The Veliger, Vol. 27, No. 2

Explanation of Figures 13 to 16

Figure 13. Topographical view of the female gonad of Diplodon
chilensis chilensis. The follicles (F) in the visceral mass surround
the intestine (I). Scanty interstitial tissue (IT) is present among
follicles. x 20.

Figure 14. Previtellogenic oocyte bulging from the follicle wall
(arrow). Protruding into the lumen (L) growing oocytes can be
seen attached by a cytoplasmic stalk (arrow head). x 500.

follicle wall, and the largest ones are attached to the fol-
licle wall by a short, broad stalk (Figure 14). The cyto-
plasm is basophilic and the nucleus is large, stains lightly,
and has disperse chromatin with one or two prominent
basophilic or eosinophilic nucleoli (Figure 14).

Growing oocytes—vitellogenic oocytes: As the oocytes —

grow they elongate and protrude into the center of the
follicles. The nucleus migrates to the distal or free end of
the cell (Figures 14, 15). The stalk becomes thinner and

Figure 15. Growing (vitellogenic) oocyte with slender stalk.
Oogonium (OG) and wall cell nuclei (arrow) embedded in the
follicle wall. x 500.

Figure 16. Full grown oocytes in follicles. The vitelline mem-
brane is sloughed away in some (arrows). Growing oocytes (ar-
row heads). A gonoduct can be seen. x 500.

the oocytes increase in size as yolk accumulates. Bundles
of fibrillar material can be seen in the stalk and in the
cytoplasm close to the stalk (Figure 15). The nucleus en-
larges and stains less heavily as the chromatin disperses.
The nucleoli continue to grow and in some oocytes are
seen to be eosinophilic or basophilic.

Full grown oocytes (morphologically mature): These
oocytes have become freed from the follicle wall and have
moved into the lumen. They are more regular in outline

S. Peredo & E. Parada, 1984

than the attached oocytes, and they are larger than vitel-
logenic oocytes, even though some of the latter can reach
a larger size than the free ones. Full grown oocytes can
reach up to 150 um in diameter. The germinal vesicle is
intact and lightly stained, with dispersed chromatin; the
nucleoli are prominent. The cytoplasm is loaded with vi-
telline platelets (Figure 16).

One can see in developed oocytes (growing and full
grown oocytes) a covering, the vitelline membrane, which
is rather thick and prominent close to the cytoplasmic stalk
in attached oocytes (Figures 15, 16).

The interstitial tissue consists of vesicular connective
tissue in which are abundant cells similar to those called
Cell Type A by TRANTER (1958) although they were not
seen within the follicles in the present study. These cells
are especially abundant in the tissue surrounding the in-
testine (Figure 13).

The gonoducts show the same features described for the
gonoducts of the male gonad (Figures 14, 16).

DISCUSSION

The structure of the gonad of Diplodon chilensis chilensis
corresponds largely to that described for the fresh-water
mussels Anodonta cygnea (PURCHON, 1968), Sphaerium
sumile (GILMORE, 1917), Lamellidens corrianus (NAGA-
BHUSHANAM & LOHGAONKER, 1978), and some marine
bivalves, in which the gonad is a branched gland that
terminates in a network of follicles occupying a large part
of the visceral mass. A system of branched ducts, the gono-
ducts, evacuate ripe germ cells during spawning periods.
Diplodon ch. chilensis differs from other bivalves, such as
Mytilus edulis, in which the gonad penetrates into mantle
tissue (SASTRY, 1977). Copulatory organs and accessory
glands are absent.

Although macroscopic sexual dimorphism is not pres-
ent, microscopic observations show that Diplodon ch. chi-
lensis is strictly gonochoric, because even in the smallest
specimens sampled (16 mm) only male or female follicles
could be recognized in the same individual.

Male germ cells correspond with the usual types formed
during spermatogenesis. No indifferent or primordial germ
cells, described for some pelecypods (TRANTER, 1958;
LuBET, 1959), were recognized in Diplodon ch. chilensis.
At least two types of spermatogonia can be recognized.
The first type (type 1 spermatogonia) would be primitive
spermatogonia, less advanced than the second type rec-
ognized (type 2 spermatogonia) which would be definitive
spermatogonia since these are the end products of sper-
matogonial mitosis. Type 2 spermatogonia directly give
rise to primary spermatocytes.

The variable appearance of the nuclei of primary sper-
matocytes corresponds to the various configurations of
meiotic prophase (Figures 5, 6). Primary spermatocytes
give rise to secondary spermatocytes. These are seen less
commonly than their predecessors. Apparently, division is
very rapid at this stage, with the secondary spermatocytes

Page 131

giving rise to the first type of spermatid characterized by
the nuclear vacuole, which would correspond to the onset
of the acrosomal granule formation. Spermatids with elon-
gated nuclei are cells in advanced stages of differentiation
into spermatozoa.

The eosinophilic zone described in one of the ends of
the sperm head corresponds to the midpiece of the sper-
matozoa and possibly consists of an aggregate of mito-
chondria as described in Haliotis rufescens (YOUNG & DE
MarTINI, 1970). This view is supported by the exami-
nation of fresh smears in which the flagellum is seen
emerging from the eosinophilic mass (Figure 11).

The multinucleated spherical dark bodies observed in
the follicles of many males (Figures 10, 12) would be cells
of atypical spermatogenesis according to LOOSANOFF (1953)
who described them in the spermatogenesis of Cyprina
islandica and earlier in Mercenaria mercenaria (LOOSANOFF,
1937a). They have also been described in Mya arenaria
(CoE & TURNER, 1938; SHAW, 1965; PORTER, 1974) as
well as in the unionids Anodonta anatina (BLOOMER, 1936),
A. cygnea (BLOOMER, 1946), and A. grandis (VAN DER
SCHALIE & LocKE, 1941). According to HEARD (1975)
these abnormal cells are of widespread occurrence in the
Unionacea, having been found in 43 species of 17 genera
in the families Amblemidae, Hyriidae, Margaritiferidae,
and Unionidae. Coz & TURNER (1938) point out that in
some cases such multinucleated dark bodies may break
apart and continue further development, finally reaching
the stage of spermatozoa. BLOOMER (1946) inferred that
in A. cygnea these atypical cells (sperm-morulae) meta-
morphosed into mature spermatozoa based on the ob-
served disappearance of sperm morulae just prior to the
appearance of large numbers of spermatozoa. More often
they become pycnotic and are cytolized. The observations
made in the present study do not elucidate the ultimate
fate of these abnormal cells.

Oogenesis in Diplodon ch. chilensis has the usual char-
acteristics described for other fresh-water and marine
mollusks. Growing oocytes with a cytoplasmic stalk have
also been described for Anodonta (BEAMS & SEKHON, 1966),
Sphaerium simile (ZUMOFF, 1973), and in several Chilean
marine bivalves (CIFUENTES, 1975; LOZADA & REYES,
1981). In gastropods, HUAQUIN (1979) described previ-
tellogenic oocytes attached by a stalk to the germinative
epithelium of the ovary in Concholepas concholepas, and a
similar situation was described for Halvotis rufescens
(YOUNG & DE MarTINI, 1970). BEAMS & SEKHON (1966)
described abundant and closely packed microtubules in
the stalks of developing oocytes. These authors assign a
mechanical and also a possible nutritional role for these
microtubules in the growing oocyte.

The observations made in the above-mentioned several
species and those made in the present study indicate that
oocytes apparently remain attached by means of the cy-
toplasmic stalk to the ovarian wall during much of their
development. In Diplodon ch. chilensis oocytes up to 120
um in diameter could be seen to be connected to the fol-

Page 132

The Veliger; Voli 27-7 NowZ

licular wall, although it was not possible to determine
exactly when they became detached.

An intact germinal vesicle in full grown oocytes indi-
cates that they are not physiologically mature. In these
oocytes meiosis either may be arrested at early prophase,
in the vegetative phase (RAVEN, 1966), or meiosis may not
have started yet, as has been reported for other bivalves
(LoosANOFF, 1937a, b; 1953). Therefore, in Diplodon ch.
chilensis either the germinal vesicle would initiate matu-
ration just before spawning, or eggs are released with the
nucleus intact and the initiation of meiosis would occur
after the sperm has penetrated the egg (activation), as has
been reported for other fresh-water bivalves (OKADA, 1935;
ZUMOFF, 1973) and marine mollusks (BRETSCHNEIDER &
RAVEN, 1951; GALSTOFF, 1961; STICKNEY, 1963). LILLIE
(1901) reported that in the unionid Elliptio complanatus
diploid primary oocytes and not mature haploid ova were
released from the ovaries and the reduction division of
these cells did not occur until after sperm penetration (in
the marsupial demibranchs).

The rather thick vitelline membrane that covers oocytes
of Diplodon ch. chilensis is characteristic of many fresh-
water bivalves (FRETTER & GRAHAM, 1964). No evidence
of a second cover, the chorion, as described for several
bivalves including the fresh-water mussel Anodonta (BEAMS
& SEKHON, 1966), have been found in Diplodon ch. chi-
lensis.

The meaning and significance of interstitial cells seen
in males and females of Diplodon ch. chilensis is not clear.
LOOSANOFF (1937a, b) assigns to cells of the surrounding
connective tissue (amoebocytes) a nutritional role in the
active phase of the reproductive cycle of Mercenaria mer-
cenaria. TRANTER (1958) ascribes to these cells a resorp-
tive function in follicles emptied from gametes after
spawning and during early development in Pinctada al-
bina. No evidence for any of these roles could be obtained
in the present study since interstitial cells were always
seen outside the follicles and with no connection to the
germinal cells.

There was no observed difference in gametogenesis in
different size classes. Diplodon ch. chilensis reaches sexual
maturity at a size smaller than 16 mm, the size of the
smallest specimens analyzed in this study.

ACKNOWLEDGMENTS

This work was supported with funds from the Direccién
de Investigacion, Catholic University of Chile-Santiago
and Comision de Investigacion, Catholic University of
Chile-Temuco. The authors are indebted to Dr. E. Bus-
tos-Obregon for his valuable suggestions and to V. Leyton
and S. Bustos for their technical assistance and critical
reading of the manuscript.

LITERATURE CITED

Beams, H. W. & S. S. SEKHON. 1966. Electron microscope
studies on the oocyte of the fresh-water mussel (Anodonta)

with special reference to the stalk and mechanism of yolk
deposition. J. Morph. 119:477-501.

BERGE, W. F. & M. T. J. HILLEBRAND. 1974. Organochlorine
compounds in several marine organisms from the North and
the Dutch Wadden Sea. Neth. J. Sea Res. 8:361-368.

BLooMER, H. H. 1936. A note on the sex of Anodonta anatina.
Proc. Malacol. Soc. Lond. 22:129-134.

BLooMER, H. H. 1946. The seasonal production of sperma-
tozoa and other notes on the biology of Anodonta cygnea (L.).
Proc. Malacol. Soc. Lond. 27:62-68.

BRETSCHNEIDER, L. H. & C. RAVEN. 1951. Structural and
topochemical changes in the egg cells of Limnaea stagnalis
L. during oogenesis. Arch. Neérl. Zool. 10:1-31.

BussE, K. 1970. Nuevo método para medir flujos de agua
producidos por organismos filtradores. Medicion experi-
mental en Diplodon chilensis chilensis (Gray) 1854 (Mollus-
ca, Lamellibranchiata). Not. Mens. Mus. Hist. Nat. San-
tiago, Chile 172:3-10.

CIFUENTES, A. S. 1975. Estudio sobre la biologia y cultivo de
Mytilus chilensis Hupe, 1854 en Caleta Leandro. Thesis.
University of Concepcion, Chile. 124 pp.

Cor, W. R. & H. J. TuRNER. 1938. Development of the
gonads and gametes in the soft-shell clam (Mya arenaria).
J. Morph. 62:91-111.

FRETTER, V. & A. GRAHAM. 1964. Reproduction. Pp. 127-
163. In: K. M. Wilbur & C. M. Yonge (eds.), Physiology
of Mollusca. Academic Press: New York.

GaLsTorF, P.S. 1961. Physiology of reproduction in molluscs.
Amer. Zool. 1:237-289.

GILMoRE, R. J. 1917. Notes on reproduction and growth in
certain viviparous mussels of the family Sphaeriidae. Nau-
tilus 31:16-30.

HEARD, W. H. 1975. Sexuality and other aspects of repro-
duction in Anodonta (Pelecypoda: Unionidae). Malacologia
15(1):81-103.

Huaguin, L. 1979. Analisis histolégico del ovario de Concho-
lepas concholepas (Gastropoda: Muricidae). Biol. Pesq. Chile
12:71-77.

KNAUER, G. A. & J. H. MarTIN. 1972. Mercury in a marine
pelagic food chain. Limnol. Oceanogr. 17:868-876.

LILLiE, F.R. 1901. The organization of the egg of Unio based
on a study of its maturation, fertilization and cleavage. J.
Morph. 17:227-292.

LoosanorFF, V. L. 1937a. Development of the primary gonad
and sexual phases in Venus mercenaria Linnaeus. Biol. Bull.
72:389-405.

LoosanorF, V. L. 1937b. Seasonal gonadal changes in adult
clams, Venus mercenaria (L.). Biol. Bull. 72:406-416.
LoosanorF, V. L. 1953. Reproductive cycle in Cyprina islan-

dica. Biol. Bull. 104:146-155.

Lozapa, E. & P. REYES. 1981. Reproductive biology of a
population of Perumytilus purpuratus at El Tabo, Chile. Ve-
liger 24:147-154.

LuBeET, P. 1959. Recherches sur le cycle sexuel et l’emission
des gametes chez les Mytilides et les Pectinides. Rev. Trav.
Inst. Peches Marit. 23:389-548.

NAGABHUSHANAM, R. & A. L. LOHGAONKER. 1978. Seasonal
reproductive cycle in the mussel, Lamellidens corrianus. Hy-
drobiologia 61(1):9-14.

Oxaba, K. 1935. Some notes on Musculium heterodon (Pils-
bry), a freshwater bivalve. I. The genital system and ga-
metogenesis. Sci. Rep. Tohoku Imp. Univ., ser. 4, Biol. 9:
315-328.

PorTer, R. G. 1974. Reproductive cycle of the soft-shell clam,
Mya arenaria at Skagit Bay, Washington. Fish. Bull. 72:
648-656.

S. Peredo & E. Parada, 1984

PuRCHON, R. P. 1968. The biology of the Mollusca. Pergamon
Press: London. 560 pp.

RAVEN, C. P. 1966. Morphogenesis: the analysis of molluscan
development. 2nd ed. Pergamon Press: New York. 365 pp.

REIJNDERS, P. J. H. 1980. Organochlorine and heavy metal
residues in harbour seals from the Wadden Sea and their
possible effects on reproduction. Neth. J. Sea Res. 14:30-
65.

Sastry, A. N. 1977. Reproduction of pelecypods and lesser
classes. In: A. C. Giese & J. S. Pearse (eds.), Reproduction
of marine invertebrates. Academic Press: New York. 113

SHaw, W. N. 1965. Seasonal gonadal cycle of the male soft-
shell clam, Mya arenaria, in Maryland. U.S. Fish. Wildl.
Serv., Spec. Sci. Rep. Fish. 508: 5 pp.

STICKNEY, A. P. 1963. Histology of the reproductive system of
the soft shell clam (Mya arenaria). Biol. Bull. 125:344-351.

Page 133

TRANTER, D. T. 1958. Reproduction in Australian pearl oys-
ters (Lamellibranchia). II. Pinctada albina (Lamark): ga-
metogenesis. Austral. J. Mar. Freshwater Res. 9:144-158.

VAN DER SCHALIE, H. & F. Locke. 1941. Hermaphroditism
in Anodonta grandis a freshwater mussel. Occ. Pap. Mus.
Zool. Univ. Mich. 432:1-7.

WILLIAMS, P. M. & H. V. Weiss. 1973. Mercury in the ma-
rine environment: concentration in seawater and in a pelagic
food chain. J. Fish. Res. Bd. Can. 30:293-295.

Wo LF, P. DE 1975. Mercury content of mussels from West
European coasts. Mar. Pollut. Bull. N.S. 7:36-38.

YOUNG, J. S. & J. DE MarTINI. 1970. The reproductive cycle,
gonadal histology and gametogenesis of the red abalone Hal-
iotis rufescens (Swainson). Calif. Fish Game 56:298-306.

ZumorF, C. H. 1973. The reproductive cycle of Sphaerium
simile. Biol. Bull. 144:212-228.

The Veliger 27(2):134-139 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

The Effects of Aerial Exposure and Desiccation on the

Oxygen Consumption of Intertidal Limpets

by

ALASTAIR J. INNES!

Portobello Marine Laboratory, University of Otago,
Dunedin, New Zealand

Abstract.

Aquatic and aerial rates of oxygen consumption were determined for the intertidal proso-

branch limpets Notoacmea pileopsis and Cellana radians at 10°C. Rates of oxygen consumption of the
two species did not differ significantly between aquatic and aerial environments. The aerial rates of
oxygen uptake of both species decreased significantly after a period of desiccation. The results are
discussed with reference to previous reports on the respiration of acmaeid and patellid limpets in air

and water.

INTRODUCTION

A FEATURE of the rocky shores of New Zealand is the
presence of an acmaeid limpet, Notoacmea pileopsis
(Hombron & Jacquinot, 1841), in the splash zone
(MorTON & MILLER, 1968). Acmaeid limpets retain a
primitive aspidobranch gill (PURCHON, 1968) and are more
frequently encountered in low shore or subtidal habitats.
Previous respiratory studies on intertidal and subtidal ac-
maeids have reported depressed rates of oxygen consump-
tion during aerial exposure (BALDWIN, 1968; MCMAHON
& RUSSELL-HUNTER, 1977). In contrast, patellid limpets,
which possess secondary pallial gills, are often found on
the upper levels of the shore, and several species appear
capable of maintaining aerobic metabolism during emer-
sion (BANNISTER, 1974; BRANCH & NEWELL, 1978;
HOULIHAN & NEWTON, 1978; BRANCH, 1979). In the
present study, the oxygen consumption of Notoacmea pi-
leopsis in water and air is investigated to determine wheth-
er this limpet’s vertical distribution on the shore is cor-
related with an enhanced capacity for aerial gas exchange
as has been demonstrated for other gastropods (MICAL-
LEF, 1967; MICALLEF & BANNISTER, 1967; MCMAHON &
RUSSELL-HUNTER, 1977; HOULIHAN, 1979; HOULIHAN &
INNES, 1982a, b). The relationship between aquatic and
aerial oxygen uptake is also determined for a common
intertidal patellid limpet, Cellana radians (Gmelin, 1791),
from the same shore. The relative ability of acmaeid and
patellid limpets to respire in aquatic and aerial environ-

' Current mailing address: Department of Zoology, University
of the West Indies, St. Augustine, Trinidad, West Indies.

ments is discussed with respect to their principal organs
of gas exchange (MCMAHON & RUSSELL-HUNTER, 1977).

BALDWIN (1968) demonstrated that the aerial oxygen
consumption of acmaeid limpets is significantly depressed
after a period of desiccation, but no comparable data are
available for patellid limpets. In the present study the
effects of desiccation on the aerial rates of oxygen con-
sumption of both Notoacmea pileopsis and Cellana radians
have been investigated and the results are discussed in
relation to the respiratory structures of each species. Com-
parisons are made with a number of other intertidal
prosobranchs (SANDISON, 1966; BALDWIN, 1968; SHIRLEY
et al., 1978).

MATERIALS anD METHODS

This work was carried out at the Portobello Marine Lab-
oratory, New Zealand, between August and October 1982.
The prosobranchs investigated in the present study are
the acmaeid limpet Notoacmea pileopsis, which is distrib-
uted in the splash zone, and the patellid limpet Cellana
radians, which is commonly found in the intertidal zone
(MorTON & MILLER, 1968; POWELL, 1979). All experi-
mental animals were collected from Allans Beach, Por-
tobello.

After collection, the snails were held in a running sea-
water aquarium without access to food for 7 to 9 days
prior to experimentation. The aquarium seawater tem-
perature varied between 7 and 10°C and the salinity was
relatively constant at 33.5%o. Experiments were carried
out at 10°C and the snails were held at the experimental
temperature for two hours prior to respirometry com-
mencing. Experiments took place in constant temperature
water baths controlled to +0.1°C.

Aerial rates of oxygen consumption were measured us-

A. J. Innes, 1984

ing constant pressure respirometers described by DAvIEs
(1966). The limpets were allowed to recover extra-cor-
poreal fluid as described by HOULIHAN & NEWTON (1978)
prior to experiments commencing. For desiccation exper-
iments the respirometer bottles containing the snails were
placed in desiccation chambers and held in a constant
temperature room at 10°C for periods of 1, 4, and 8 h.
Silica gel was used as a desiccating agent and relative
humidity (RH) was constant at 20%. Aerial respirometry
- was carried out as described by HOULIHAN et al. (1981).
The position of the snail in the respirometer was moni-
tored and rates of oxygen consumption calculated for pe-
riods when the animal was seen to be inactive. All rates
of oxygen consumption have been converted to STP. Some
determinations of aerial oxygen consumption for Notoac-
mea were made with up to three similar-sized snails in a
respirometer in order to increase the accuracy of the mea-
surements. These data are expressed as mean oxygen con-
sumption for a mean weight animal.

Aquatic oxygen consumption was measured by the closed
bottle technique described by HOULIHAN (1979). The lim-
pets were left overnight to attach and settle in the respi-
rometer bottles in running aerated seawater prior to ex-
periments commencing (HOULIHAN & NEwTOoN, 1978).
After the flasks were sealed, the seawater was stirred every
5 min with a magnetic stirrer, and rates of oxygen con-
sumption were calculated only for those animals that re-
mained inactive throughout the experiment. A blank bot-
tle without an animal was run as a control with each set
of experiments. The oxygen content of the seawater at the
beginning and end of each experiment was determined by
the Winkler technique (STRICKLAND & PARSONS, 1972).
Oxygen consumption was calculated from the decline in
oxygen content of the seawater, the volume of water in
the respirometer bottle, and the duration of the experi-
ment. The oxygen content of the seawater in the flask was
never allowed to fall below 80% of the saturated value
during experiments (INNES, 1982).

At the end of each experiment the limpets were removed
from their shells and dried to a constant weight at 65°C.

Measurements of aquatic and aerial (undesiccated) res-
piration were made on a wide size range of animals in
order to establish relationships between dry weight and
oxygen consumption. The results were subjected to regres-
sion and covariance analysis (SNEDECOR & COCHRAN,
1972) following the procedure of WILSON (1975). The
results of regression analysis using data transformed by
logarithms to the base 10 are shown in their logarithmic
form. The mean dry flesh weight + SE of all the Notoac-
mea pileopsis used in these experiments was 42.5 + 2.5
mg (n = 46) while that of the larger Cellana radians was
219.6 + 24.2 mg (n = 41). Standard dry flesh weight an-
imals, Notacmea pileopsis (40 mg) and Cellana radians (200
mg), were used to calculate ratios of aquatic to aerial
oxygen consumption and to describe the effects of desic-
cation.

Narrow weight ranges of Notoacmea pileopsis (30-50

Page 135

Oxygen consumption, ul O2h7!

5
10 50 100

Dry flesh weight, mg
Figure 1

Relationships between dry flesh weight (mg) and oxygen con-
sumption (uL O, h~'!) of Notoacmea pileopsis in air (O- - -O)
and seawater (@——®) at 10°C; the lines are drawn from the
regression analyses provided in the text.

mg) and Cellana radians (160-240 mg) were selected for
desiccation experiments. The experimentally determined
rates of oxygen consumption of individual animals were
transformed to those of standard dry weight Notoacmea
(40 mg) and Cellana (200 mg) using the scaling equation:

Vo,(s) = (me) Vo,(e)

W(s)
(NEWELL, 1979)

—

Oxygen consumption, yl Ozh"!
a
fo)

T [aU SLGSLEUY

50 100

—_
XS
conn

Limi LES oc
500 800

Dry flesh weight, mg
Figure 2

Relationships between dry flesh weight (mg) and oxygen con-
sumption (uL O, h~') of Cellana radians in air (O- - -O) and
seawater (@——®) at 10°C; the lines are drawn from the regres-
sion analyses supplied in the text.

Page 136

Table 1

Ratios of aquatic oxygen consumption for a number of

acmaeid and patellid limpets; ratios have been calculated

at the temperatures indicated for standard weight animals
using data supplied in the references.

Tem- Aquatic
pera- to
ture aerial
Species (°C) ratio Reference
Acmaeidae:
Notoacmea pileopsis 10 1:0.95 present study
Collisella scabra 15 1:0.44 BALDWIN (1968)
Collisella digitalis 15 1:0.89 BALDWIN (1968)
Collisella testudinalis 22 1:0.40 McManHon &
RUSSELL-HUNTER
(1977)
Patellidae:
Cellana radians 10 1:0.97 present study
Patella lusitanica 20 1:3.13. BANNISTER (1974)
Patella caerulea 20 1:0.45 BANNISTER (1974)
Patella oculus 25 1:0.99 BRANCH & NEWELL
(1978)
Patella cochlear 25 1:1.04 BRANCH & NEWELL
(1978)
Patella granularis 25 1:0.94 BRANCH & NEWELL
(1978)
Patella vulgata 10 1:1.41 HOUuLIHAN &
NEWTON (1978)
Patella granatina 25 1:0.99 BRANCH (1979)

where V,,(s) is the calculated rate of oxygen consumption
of a standard dry weight animal in wh O, h7'; W(s), the
dry flesh weight of a standard animal in mg; W(e), the
dry flesh weight of the experimental animal in mg; V_,(e),
the experimentally determined oxygen consumption in wL
O, h~'; 6, the scaling exponent (aerial 6 values of 0.717
and 0.645 determined for Notoacmea and Cellana respec-
tively in the present study are used). Statistical compari-
sons between rates of oxygen consumption under different
experimental conditions were made by Students ¢(-test
(SNEDECOR & COCHRAN, 1972). Means + SE are used
throughout.

RESULTS
Oxygen Consumption in Air and Seawater

Rates of oxygen consumption in air and water of a size
range of Notoacmea pileopsis are presented in Figure 1.
The regression analyses describing the relationships be-
tween dry flesh weight (X, mg) and oxygen consumption
(Y, wl O;\h=) are

Air log,oY = 0.717 log,,.X + 0.036, where n = 21
and r = 0.71.

Seawater log,Y = 0.643 log,,.X + 0.176, where n = 25
and r = 0.80.

The relationships between dry flesh weight and oxygen

The Veliger, Vol. 27, No. 2

“7 Notoacmea pileopsis

jee

(9) (8) (7) (8)

O i) eos i,

Cellana radians

Oxygen consumption, ul O2 h-!

75
70
60
50
40119) (8) (8) (8)
35 Pe Pa a | |
Or 4 8
Time, h
Figure 3

Rates of aerial oxygen consumption (uL O, h~') + SE of stan-
dard dry weight Notoacmea pileopsis (40 mg) and Cellana radians
(200 mg) after a brief period of aerial exposure (@) and after 1
h, 4h, and 8 h desiccation at 20% RH (O); sample sizes (n) are
shown in parentheses.

consumption in air and water are both significant (P <
0.05). Analysis of covariance showed no significant dif-
ferences in either slope or elevation between the rates of
oxygen consumption of Notoacmea pileopsis in aquatic and
aerial environments. The ratio of aquatic to aerial oxygen
consumption for a standard dry weight animal (40 mg) is
1:0.95 at 10°C.

Aquatic and aerial rates of oxygen consumption of Cel-
lana radians are plotted as a function of dry flesh weight
in Figure 2. The relationships between dry flesh weight
(X, mg) and oxygen consumption (Y, wL O, h~') are
described by the regression analyses

Air log,,.Y = 0.645 log,,.X* + 0.323, where n=
20 and 7 = 0.94.

A. J. Innes, 1984

Page 137

Table 2

Ratios of the aerial oxygen consumption of gastropods soon after emersion to that of animals subjected to a period of

desiccation; ratios for the species in the present study are calculated after 4 h desiccation (20% RH) at 10°C for comparison

with those reported by SANDISON (1966) after 3 h drying at 18°C and by BALDWIN (1968) after 3 h drying at 22°C; the

principal respiratory organ of each species is indicated; NS denotes no significant difference between desiccated (after
drying overnight) and undesiccated rate.

Species

bipectinate gill
bipectinate gill
bipectinate gill
pallial gills
unipectinate gill
unipectinate gill
unipectinate gill
unipectinate gill
unipectinate gill

Notoacmea pileopsis
Collisella scabra
Collisella digitalis
Cellana radians
Littorina saxatilis
Littorina littorea
Littorina obtusata
Nucella lapillus
Littorina irrorata

Seawater log,Y = 0.559 log,,.X + 0.511, where n = 21
and n = 0.83.

The correlation coefficients for the aerial and aquatic
regression analyses are both significant (P < 0.05). Anal-
ysis of covariance revealed no significant differences in
either slope or elevation between the rates of oxygen con-
sumption determined in air and seawater. The aquatic to
aerial ratio for a standard weight animal (200 mg) is
1:0.97 at 10°C.

Effect of Desiccation on Aerial Oxygen Consumption

Aerial rates of oxygen consumption of Notoacmea pi-
leopsis after 1, 4, and 8 h desiccation are all significantly
lower (P < 0.001) than rates determined for limpets that
had experienced a brief period of aerial exposure (Figure
3). The rates measured after 1 and 4 h desiccation are
also significantly different (P < 0.05). The aerial oxygen
consumption of Notoacmea decreases by over 50% at all
three levels of desiccation—1 h (51%), 4 h (68%), and 8
h (57%).

The aerial oxygen consumption of Cellana radians de-
creases significantly after 1 h (P < 0.001), 4h (P < 0.05),
and 8 h (P < 0.01) desiccation compared to limpets after
a brief period of aerial exposure (Figure 3). There are no
significant differences between the rates after 1, 4, and 8
h desiccation. Decreases in the aerial oxygen consumption
of Cellana radians after 1 h (36%), 4 h (24%), and 8 h
(32%) desiccation are less than those reported for Notoac-
mea pileopsis.

DISCUSSION

In terms of its respiration in air and water, the acmaeid
limpet Notoacmea pileopsis is an exception to the pattern
of depressed rates of aerial oxygen consumption previ-
ously described for prosobranch limpets possessing prim-
itive aspidobranch gills (BALDWIN, 1968; HUGHES, 197 1a;

Principal respiratory organ

Ratio of oxygen

consumption Reference

1:0.32 present study

1:0.43 BALDWIN (1968)
1:0.25 BALDWIN (1968)
1:0.76 present study

1: OW72 SANDISON (1966)
1:0.40 SANDISON (1966)
1:0.38 SANDISON (1966)
1:0.52 SANDISON (1966)

NS SHIRLEY et al. (1978)

McManHon & RUSSELL-HUNTER, 1977). The distribu-
tion of Notoacmea pileopsis may be compared with that of
some neritids (HUGHES, 1971b; Lewis, 1971; COLEMAN,
1976; HOULIHAN, 1979) and trochids (MICALLEF, 1967;
MICALLEF & BANNISTER, 1967; HOULIHAN & INNES,
1982a, b) which also retain a bipectinate ctenidium and
are subjected to long periods of aerial exposure.

The pattern of respiration in air and water for a num-
ber of acmaeid limpets (Table 1) seems somewhat similar
to that described in comparative studies of trochids (MI-
CALLEF, 1967; MICALLEF & BANNISTER, 1967; HOULIHAN
& INNES, 1982a, b), z.e., high shore species maintain aero-
bic metabolism during emersion while their low shore
counterparts have reduced rates of oxygen consumption
in. air. Increased vascularization of the mantle
(DESHPANDE, 1957; FRETTER & GRAHAM, 1962) may en-
hance aerial oxygen uptake in some high shore trochids
(NEWELL, 1973) but it is not clear whether Notoacmea
possesses any structural adaptations to promote aerial gas
exchange.

The ratio of aquatic to aerial oxygen consumption of
Notoacmea pileopsis is very similar to that of the patellid
limpet Cellana radians (Table 1) whose oxygen uptake did
not change significantly between aquatic and aerial en-
vironments at 10°C (Figure 2). Patellid limpets, whose
principal respiratory organs are secondary pallial gills
(PURCHON, 1968), generally appear well adapted for ae-
rial oxygen uptake (Table 1), although aquatic to aerial
ratios vary with size and temperature and may be modi-
fied to meet the overall energy balance of individual species
(BRANCH & NEWELL, 1978; BRANCH, 1979; NEWELL &
BRANCH, 1980).

The patterns of aerial oxygen consumption displayed
by Notoacmea pileopsis and Cellana radians immediately
after emersion and after periods of desiccation are re-
markably similar (Figure 3). The oxygen uptake of both
species decreased significantly after a relatively short (1

Page 138

The Veliger; VoleZ7aNowZ

h) period of desiccation, and remained relatively constant
during subsequent drying. It therefore appears that proso-
branch limpets have two levels of aerial oxygen consump-
tion: (1) a rate immediately on emersion (in this instance
similar to the aquatic rate) and (2) a depressed rate in-
dicative of desiccation stress (COLEMAN, 1976).

The decrease in aerial oxygen consumption of Notoac-
mea pileopsis after a period of desiccation is very similar
to that reported for other acmaeids (BALDWIN, 1968), and
the vertical range of this limpet does not appear to be
correlated with any adaptations to minimize the respira-
tory effects of drying (Table 2). With the reservations that
Table 2 contains limited data and comparisons are made
using gastropods of different size ranges (WOLCOTT, 1973)
there is some indication of a correlation between the prin-
cipal organ of gas exchange and the effect of desiccation
on aerial oxygen uptake. Desiccation appears to have a
greater effect on the oxygen uptake of acmaeid limpets
(BALDWIN, 1968; present study) than that of limpets pos-
sessing pallial gills (present study) or other prosobranchs
with modified respiratory organs (SANDISON, 1966;
SHIRLEY et al., 1978).

The greater decrease in oxygen uptake during desic-
cation reported for acmaeids (Figure 3; Table 2) may
involve the production of mucus slowing down both water
loss (WoLcoTT, 1973) and oxygen uptake. In addition,
the gill filaments may clump together during drying to
occlude a large area of the respiratory surface.

The depressed rates of aerial oxygen uptake reported
for Notoacmea pileopsis and Cellana radians during desic-
cation may conserve energy during aerial exposure
(BRANCH & NEWELL, 1978; BRANCH, 1979; NEWELL &
BRANCH, 1980). The desiccated rates in both instances
are, however, significantly lower than the resting aquatic
rate, and, if aerobic metabolism in air were to fall below
the minimum maintenance level (NEWELL, 1979), then
anaerobic metabolism may become important (BAYNE et
al., 1976; WIESER, 1980).

ACKNOWLEDGMENTS

This work was carried out at the Portobello Marine Lab-
oratory under tenure of a University of Otago Postdoc-
toral Fellowship and was supported by grants from the
University of Otago Research Committee. I thank Asso-
ciate Professor J. B. Jillett for his comments on the manu-
script and the Department of Zoology, University of Ota-
go, for the use of equipment and other facilities. I also
thank an anonymous referee for helpful and constructive
suggestions.

LITERATURE CITED

BALDWIN, S. 1968. Manometric measurements of respiratory
activity in Acmaea digitalis and Acmaea scabra. Veliger 11:
79-82.

BANNISTER, J. V. 1974. The respiration in air and in water
of the limpets Patella caerulea (L.) and Patella lusitanica
(Gmelin). Comp. Biochem. Physiol. 49A:407-411.

BayNE, B. L., C. J. BAyNE, T. C. CAREFOoT & R. J. THOMPSON.
1976. The physiological ecology of Mytilus californianus
Conrad: 2. Adaptations to low oxygen and air exposure.
Oecologia 22:229-250.

BRANCH, G. M. 1979. Respiratory adaptations in the limpet
Patella granatina: a comparison with other limpets. Comp.
Biochem. Physiol. 62A:641-647.

BRANCH, G. M. & R. C. NEWELL. 1978. A comparative study
of metabolic energy expenditure in the limpets Patella co-
chlear, P. oculus and P. granularis. Mar. Biol. 49:351-361.

COLEMAN, N. 1976. Aerial respiration of nerites from the north-
east coast of Australia. Aust. J. Mar. Freshwater Res. 27:
455-466.

Davies, P. S. 1966. A constant pressure respirometer for me-
dium-sized animals. Oikos 17:108-112.

DESHPANDE, R. D. 1957. Observations on the anatomy and
ecology of British trochids. Doctoral Thesis, University of
Reading, U.K.

Fretrer, V. & A. GRAHAM. 1962. British prosobranch mol-
luscs. Royal Society London.

HOuLinaNn, D. F. 1979. Respiration in air and water of three
mangrove snails. J. Exp. Mar. Biol. Ecol. 41:143-161.
Hou.inan, D. F. & A. J. INNES. 1982a. Respiration in air
and water of four Mediterranean trochids. J. Exp. Mar.

Biol. Ecol. 57:35-54.

HOuLinan, D. F. & A. J. INNEs. 1982b. Oxygen consumption,
crawling speeds, and cost of transport in four Mediterra-
nean intertidal gastropods. J. Comp. Physiol. 147:113-121.

HOou.inan, D. F., A. J. INNEs & D. G. Dey. 1981. The
influence of mantle cavity fluid on the aerial oxygen con-
sumption of some intertidal gastropods. J. Exp. Mar. Biol.
Ecol. 49:57-68.

Hou .inan, D. F. & J. R. L. NEwron. 1978. Respiration of
Patella vulgata on the shore. Pp. 39-46. In: D. S. McLusky
& A. J. Berry (eds), Pp. 39-46. Physiology and behaviour
of marine organisms, Proceedings of the 12th European
Symposium of Marine Biology. Pergamon Press: Oxford.

HuGHEs, R. N. 1971a. Ecological energetics of the keyhole
limpet Fissurella barbadensis Gmelin. J. Exp. Mar. Biol.
Ecol. 6:167-178.

HuGues, R. N. 1971b. Ecological energetics of Nerta (Ar-
cheogastropoda, Neritaceae) populations on Barbados, West
Indies. Mar. Biol. 11:12-22.

INNEs, A. J. 1982. Respiration in air and water of intertidal
gastropods. Doctoral Thesis, University of Aberdeen, U.K.

Lewis, J. B. 1971. Comparative respiration of some tropical
intertidal gastropods. J. Exp. Mar. Biol. Ecol. 6:101-108.

McManuon, R. F. & W. D. RUSSELL-HUNTER. 1977. Tem-
perature relations of aerial and aquatic respiration in six
littoral snails in relation to their vertical zonation. Biol.
Bull. 152:182-198.

MIcaLLeF, H. 1967. Aerial and aquatic respiration of certain
trochids. Experientia 23:52.

MIcALLEF, H. & W. H. BANNISTER. 1967. Aerial and aquatic
oxygen consumption of Monodonta turbinata (Mollusca:
Gastropoda). J. Zool., Lond. 151:479-782.

Morton, J. & M. MILLER. 1968. The New Zealand sea
shore. Collins: London.

NEWELL, R. C. 1973. Factors affecting the respiration of in-
tertidal invertebrates. Amer. Zool. 13:513-528.

NEWELL, R. C. 1979. Biology of intertidal animals. Marine
Ecological Surveys Ltd.: Kent.

Ae nines 984

NEWELL, R. C. & G. M. BRANCH. 1980. The influence of
temperature on the maintenance of metabolic energy bal-
ance in marine invertebrates. Adv. Mar. Biol. 17:329-396.

PoweELL, A. W. B. 1979. New Zealand Mollusca. Collins:
Auckland.

PuRCHON, R. D. 1968. The biology of the Mollusca. Perga-
mon Press: Oxford.

SANDISON, E. E. 1966. The oxygen consumption of some in-
tertidal gastropods in relation to zonation. J. Zool., Lond.
149:163-173.

SHIRLEY, T. C., G. J. DENoUx & W. B. STICKLE. 1978. Sea-
sonal respiration in the marsh periwinkle Littorina irrorata.
Biol. Bull. 154:322-334.

Page 139

SNEDECOR, G. W. & W. G. COCHRAN. 1972. Statistical meth-
ods. Iowa State University Press: Ames, Iowa.

STRICKLAND, J. D. H. & T. R. Parsons. 1972. A practical
handbook of seawater analysis. Bull. Fish. Res. Bd. Can.
No. 167, 2nd edition.

WIESER, W. 1980. Metabolic end products in three species of
marine gastropods. J. Mar. Biol. Ass. U.K. 60:175-180.

WILSON, J. B. 1975. Teddybear—a statistical system. N.Z.
Statistician 10:36-42.

Wo coTt, T. G. 1973. Physiological ecology and intertidal
zonation in limpets (Acmaea): a critical look at “limiting
factors.” Biol. Bull. 145:389-422.

The Veliger 27(2):140-142 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

Predator Deterrence by Flexible Shell Extensions of the

Horse Mussel Modiolus modiolus

by

MARY M. WRIGHT anb LISBETH FRANCIS

Biology Department, Bates College,
Lewiston, Maine 04240

Abstract.

Flexible, tapering hairs, or awns, on the periostracum of the horse mussel Modiolus

modiolus discourage attachment by the predatory whelk Thavs lapillus. This conclusion is based on
laboratory preference tests demonstrating a higher frequency of attachment to the hairless blue mussel
Mytilus edulis. Removal of the awns of the horse mussel results in more nearly equal attachment to
both mussel species. To our knowledge, this is the first time that a selective advantage has been
demonstrated experimentally for any periostracum.

INTRODUCTION

TWO MUSSEL species occur commonly along the rocky coast
of Maine. The blue mussel Mytilus edulis (Linnaeus, 1758)
is found in bays and estuaries and on exposed promon-
tories at various levels in the mid to low intertidal (SEED
& Brown, 1975; MENGE, 1976). In contrast, the horse
mussel Modiolus modiolus (Linnaeus, 1758) extends from
the low intertidal to subtidal regions (BROWN & SEED,
1977).

The most obvious morphological difference between the
shells of these two mussels is the awns (hairy projections
of the periostracum at the exposed posterior margin), which
are present on Modiolus modiolus but are absent from My-
tilus edulis.

The dog whelk Thazs lapillus (Linnaeus, 1758) is a
major intertidal predator that commonly attacks the blue
mussel (MENGE, 1976), and at least occasionally attacks
the horse mussel (personal observation, MMW). Thais
attacks bivalves mechanically by drilling with the radula,
and chemically by dissolving the shell with secretions from
the accessory boring organ (GABRIEL, 1981).

SEED & BROWN (1975) report that during their labo-
ratory experiments, 7hais lapillus never attacked the horse
mussel; NIELSEN (1975) suggests that the hairy or spiny
shell texture may discourage attack by Buccinum undatum
Linnaeus, 1758, a whelk that attacks bivalves by wedging
the lip of its own shell between the open valves to hold
them apart, then reaching in to tear off bits of flesh.

We suspect that the hairy periostracum of Modiolus

modulus might discourage attachment and boring by Thais

lapillus, which depends on prolonged, close contact with
prospective prey in order to attack and consume it.
Previous to this study, the only characteristic of bivalve
shells actually shown to hamper predation by drilling gas-
tropods was a greatly thickened valve (Vermeij, 1978).

MATERIALS ann METHODS
Collection and Holding of Animals

Animals were collected occasionally from 16 October
1982 to 9 March 1983 on Bailey Island, Maine, a few
hundred meters from a section of rocky exposed coastline
called ‘“The Giant Staircase.”’ Freshly caught whelks were
isolated from prey and allowed to adapt to aquarium con-
ditions for at least 4 days.

All animals were kept in a filtered recirculating sea-
water system in which one third of the water was replaced
each week by ocean water that had been collected and
allowed to stand for at least a week. Temperature, salin-
ity, and pH were maintained within natural limits (8.5
to 11°C; 28 to 32 ppt.; and 7.4 to 7.5 respectively). The
tanks received light from several large windows nearby
and from fluorescent ceiling lights.

Design of Predator Choice Experiments

Three mussels of each species were selected, approxi-
mately matched for size (4 to 8 cm long), and arranged
alternately on a sheet of plastic at one end of a five gallon
aquarium. In each trial a different set of 20 whelks was
placed in rows with their anterior ends directed toward

M. M. Wright & L. Francis, 1984

BeCoO OO 6 6
900000000006

Figure 1

Spacing and arrangement of mussels (Modiolus modiolus with the
awned periostracum, and Mytilus edulis with the smooth peri-
ostracum) and whelks (Thazvs lapillus) at the outset of laboratory
predator choice trials.

the posterior margins of the mussels (Figure 1). This
seemed a suitable testing arrangement, because in the field
the mussels usually are wedged into crevices or between
neighboring mussels with only the posterior margins ex-
posed. After 24 h the number of whelks actually attached
to each species of mussel was recorded. To minimize the
possibility that the whelks were following old whelk mu-
cus trails from previous trials, a new sheet of plastic was
secured to the bottom of the tank and the mussels were
scrubbed with a wet brush before each trial.

In a second set of experiments, the shells of all mussels
were scraped with a razor blade before they were placed
in tanks. This treatment effectively removed the awns of
Modiolus modiolus.

RESULTS

With the periostracum of the mussels intact, 142 of the
whelks attached to the smoother valves of Mytilus edulis,
while only 23 attached to the hairy valves of Modiolus
modiolus (31 trials involving 620 whelks). In these trials,
the whelks attached to Mytzlus edulis much more frequent-
ly than predicted by chance (Chi-square test for goodness
of fit, x* = 86, P < 0.001). When all of the mussels were
scraped, which effectively removed the awns from the horse
mussel, a total of 99 whelks attached to Mytilus edulis,
while 72 attached to the awnless specimens of Modtolus
modulus (28 trials involving 560 whelks). While the whelks
continued to show a slight preference for Mytilus edulis
when the awns of Modiolus modiolus were removed (x? =
8.5, P < 0.005), this preference was much less marked
than when the periostracum was intact (2 x 2 test of in-
dependence, x? = 73, P < 0.001).

Page 141

DISCUSSION

Along the rocky intertidal of New England, natural or
artificial exclusion of the predatory whelk Thavs lapillus
results in monopolization of the primary space by Mytilus
edulis, while in areas of heavy whelk predation, the blue
mussel is commonly eliminated (MENGE & SUTHERLAND,
1976). Intense predation by invertebrates of the lower
shore and subtidal apparently prevents the establishment
of subtidal populations of Mytilus edulis (SEED, 1969).

Predation levels are higher and survival rates lower for
small specimens of Modiolus modiolus than for larger ones,
and rapid growth of smaller individuals results in escape
in size from predation (SEED & BROowN, 1975). This kind
of selective pressure should favor the evolution of mech-
anisms that discourage predation, especially on smaller
individuals.

Our experiments show that the shell awns of Modiolus
modiolus are an effective predator deterrent discouraging
attachment by the whelk Thais lapillus. The fact that
smaller horse mussels have more awns may be another
indication of the importance of predation and predator
deterrence among small, vulnerable individuals. The pres-
ence of these protective shell awns may allow Modiolus
modiolus to live below Mytilus edulis in the lower intertidal
and subtidal, where predator pressure is relatively intense.
Further work is presently under way to determine whether
the awns also discourage attack by other common preda-
tors such as the starfish Asterzas vulgaris (MENGE, 1979).

It is possible that shell awns and various other kinds of
shell sculpturing are advantageous not only because they
make attachment more difficult, but also because they make
an undesirable prey species easy for a prospective predator
to recognize and reject. Using crabs as predators and mus-
sels as prey, ELNER & HUGHES (1978) demonstrated the
importance of recognition time in determining the selec-
tivity of a predator. Foraging theory predicts that a pred-
ator that cannot distinguish quickly between a preferred
prey item and a common, less desirable one, will take
relatively large numbers of the less preferred type. Any-
thing that makes a less preferred prey species easy to
recognize could have a large selective advantage in such a
situation. In addition to making Modiolus modiolus more
difficult to approach and attack, the awns on the shell
may make this species easier to recognize and reject by
predators searching for more desirable prey.

While there has been considerable work on the struc-
ture and formation of the periostracum (reviewed by Sa-
LEUDDIN & PETIT, 1983; WAITE, 1983), there has been
little experimental work on periostracum function (re-
viewed by CLARK, 1976). In general, the periostracum is
presumed to protect the calcareous layers of the shell from
erosion (FRETTER & GRAHAM, 1962; SOLEM, 1974) and
to play an important role in mineralization of the shell
(CLARK, 1976).

This is the first demonstration that the periostracum of
a bivalve can discourage predation by a drilling gastropod.

Page 142

The Veliger; Vole 27-NiowZ

To our knowledge, it is also the first time that a specific
selective advantage has been demonstrated experimentally
for any periostracum.

ACKNOWLEDGMENTS

We thank Dean Schneider for substantial help in the
preparation of the manuscript, several friends for reading
and commenting, David Braslau for assistance in the field,
and Bates College Biology Department for the use of fa-
cilities and logistic support.

LITERATURE CITED

Brown, R. A. & R. SEED. 1977. Modiolus modiolus (L.)—an
autecological study. Pp. 93-100. Jn: B. F. Keegan, P. O.
Ceidigh & P. J. S. Boaden (eds.), Biology of benthic organ-
isms, 11th European Symposium on Marine Biology, Gal-
way, October 1976. Pergamon Press: Oxford.

CLARK, G. R. 1976. Shell growth in the marine environment,
approaches to the problem of marginal calcification. Amer.
Zool. 16:617-626.

ELNER, R. W. & R. NN. HuGHEs. 1978. Energy maximization
in the diet of the shore crab, Carcinus maenas (L.). J. Anim.
Ecol. 47:103-116.

FRETTER, V. & A. GRAHAM. 1962. British prosobranch mol-
luscs, their functional anatomy and ecology. Ray Society:
London. 755 pp.

GaBRIEL, J. M. 1981. Differing resistance of various mollusc
shell materials to simulated whelk attack. J. Zool. 194:363-
369.

MENGE, B. S. 1976. Organization of the New England rocky

intertidal community: role of predation, competition and en-
vironmental heterogeneity. Ecol. Monogr. 46:355-393.

MENGE, B. A. 1979. Coexistence between the seastars Asterias
vulgaris and Asterias forbes: in a heterogenous environment:
a non-equilibrium explanation. Oecologia 41:245-272.

MENGE, B. S. & J. P. SUTHERLAND. 1976. Species diversity
gradients: synthesis of the roles of predation, competition,
and temporal heterogeneity. Amer. Natur. 110:351-369.

NIELSEN, C. 1975. Observations on Buccinum undatum L. at-
tacking bivalves and on prey responses, with a short review
on attack methods of other prosobranchs. Ophelia 13:87-
108.

SALEUDDIN, A. S. M. & H. P. Petir. 1983. The mode of
formation and the structure of the periostracum. Pp. 199-
233. In: A. S. M. Saleuddin & K. M. Wilbur (eds.), The
Mollusca, Volume 4: Physiology, Part I. Academic Press:
New York.

SEED, R. 1969. The ecology of Mytilus edulis L. (Lamelli-
branchiata) on exposed rocky shores. Growth and mortality.
Oecologia 3:317-350.

SEED, R. & A. BRowN. 1975. The influence of reproductive
cycle, growth, and mortality on population structure in Mo-
diolus modiolus (L.), Cerastoderma edule (L.), and Mytilus
edulis L. (Mollusca: Bivalvia). Pp. 257-274. In: H. Barnes
(ed.), Ninth European marine biology symposium. Aber-
deen Univ. Press: Scotland.

SOLEM, A. 1974. The shell makers, introducing mollusks. John
Wiley and Sons: New York. 289 pp.

VERMEIJ, G. J. 1978. Biogeography and adaptation: patterns
of marine life. Harvard Univ. Press: Cambridge, Massa-
chusetts. 322 pp.

Waite, J. H. 1983. Quinone-tanned scleroproteins. Pp. 467-
504. In: P. H. Hochachka (ed.), The Mollusca, Volume 1,
Metabolic biochemistry and molecular biomechanics. Aca-
demic Press: New York.

THE VELIGER

© CMS, Inc., 1984
The Veliger 27(2):143-163 (October 5, 1984)

The Opisthobranchs of Cape Arago, Oregon, with Notes on
Their Biology and a Summary of Benthic
Opisthobranchs Known from Oregon
by

JEFFREY H. R. GODDARD

Oregon Institute of Marine Biology,
Charleston, Oregon 97420

Abstract. The opisthobranch mollusks from Oregon have not been well studied, and little or nothing
is known about the biology of many species. The present study consisted of field and laboratory
observations on the biology and ecology of Cape Arago opisthobranchs. Forty-six species were found,
extending the range of six northward and two southward. New food records are presented for ten
species; 21 species were observed feeding on previously recorded prey. The egg masses of a number of
species are described for the first time, and developmental data are given for 21 species. Twenty produce
planktotrophic larvae, and Doto amyra produces lecithotrophic larvae, the first such example known
from eastern Pacific opisthobranchs. Hallaxa chani, whose diet consists solely of the sponge Halisarca
sp., appears to be the first eudoridacean nudibranch known to have a subannual life cycle. Its rapid
life cycle appears to be adaptive primarily in exploiting the widely dispersed and fast growing Halisarca
sp. Data presented on the longevity of Cadlina luteomarginata and C. modesta suggest they have annual
life cycles. Nudibranchs appear to be among the most important predators of intertidal encrusting
animals at Cape Arago and probably significantly affect the diversity of the encrusting community.

Sixty-six species of benthic opisthobranchs are currently known from Oregon.

INTRODUCTION

THE OPISTHOBRANCH mollusks of Oregon have been little
studied compared with those of California to the south
and those of the San Juan Archipelago-Vancouver Island
region to the north. SOWELL (1949) studied the natural
history of opisthobranchs in the Coos Bay-Cape Arago
area in the late 1940’s and listed 19 species from that
area. Since then two relatively brief studies of Oregon
opisthobranchs have been made. SPHON (1972) reviewed
the literature mentioning Oregon opisthobranchs and re-
ported on a six-day collecting trip made in five Oregon
localities. BELCIK (1975) lists species not reported by Sphon
that he found in the Coos Bay-Cape Arago area while
studying parasites of mollusks and fish. A total of 43 ben-
thic opisthobranchs were reported in these three studies,
21 from Cape Arago.

Members of the order Nudibranchia comprise most of
the rocky intertidal opisthobranchs. Although little is
known about the biology and ecology of many northeast-

ern Pacific species (BEEMAN & WILLIAMS, 1980), those
nudibranchs that have received study have all been shown
to be carnivores that prey, as a group, on a wide variety
of sessile invertebrates (THOMPSON, 1976; MCDONALD &
NYBAKKEN, 1978; BEEMAN & WILLIAMS, 1980). Little is
known about the effects of their predation on the encrust-
ing animal communities to which they belong.

In this paper I report on observations, scattered over a
45-month period beginning in December 1979 and ending
in September 1983, of rocky intertidal opisthobranchs from
Cape Arago. The purpose of this research was to (1) de-
termine which species occur at Cape Arago, (2) examine
aspects of their biology, including food, feeding methods,
larval development, and, in a few cases, life cycles, and
(3) attempt to gain some understanding of the effects of
nudibranch predation on the encrusting animal commu-
nity at Cape Arago. Observations are presented for each
of the 46 species I found, followed by a general discussion
and comments on the benthic opisthobranchs currently
known from Oregon.

Page 144

Pacific
Ocean

6
g”

PSON
TReEE ‘| 105

vy
as

°
°
Q

CAPE ARAGO |

Figure 1
Cape Arago, Oregon (43°20'N, 124°22'W).

STUDY AREA anpD DATES oF FIELD
OBSERVATIONS

Cape Arago contains one of the widest, most physically
and biologically diverse intertidal areas between Cape
Mendocino, California, and Cape Flattery, Washington
(P. W. Frank and J. J. Gonor, personal communications;
personal observations). The study area included North,
Middle, and South coves of Cape Arago and one small
cove located just south of Cape Arago which I call Good
Witch Cove (Figure 1). Cape Arago is situated 7.3 km
southwest of the entrance to Coos Bay. Charleston and
the Oregon Institute of Marine Biology (O.I1.M.B.) are
located just inside the south side of the mouth of Coos
Bay.

North Cove

North Cove has the largest intertidal area of the four
coves. At low tide one can walk beyond Shell Island to
the outer boulder field and edge of the Macrocystis-Nereo-
cystis kelp bed located just inside Simpson Reef. North
Cove contains a mixture of sandstone shelves, outcrops,
and boulders of variable size and is protected from large
surf by Simpson Reef. Forty-two of 65 trips comprising
this study were made to the inner boulder field, one of the

most sheltered parts of North Cove (Figure 1). This boul-_

der field consists of roughly half fissured-and-pocketed
bedrock and half boulders averaging 0.25 to 0.5 m in

The’ Veliger; Vol. 27-3 NiowZ

diameter. During the calmer months (spring and summer)
much of the inner boulder field is subject to silt and de-
tritus accumulation. Few sea urchins are present, and the
area is dominated by the algae Egregia menziesii, Hedo-
phyllum sessile, Iridea flaccida, Cystoseira osmundacea,
Laminaria sp., the introduced Sargassum muticum, and the
surfgrass Phyllospadix. The undersides of boulders and
ledges support a rich variety of sessile invertebrates—the
prey of most nudibranchs—and it is under and among
these boulders that the greatest number of opisthobranch
species and individuals occurring at Cape Arago are found
(38 out of the Cape Arago total of 46).

A total of 44 trips was made to North Cove in the
following months: 12/°79; 3, 5, 6, 7/°80; 6/°81-5/’82; 8,
9/°82; and 3-9/°83. Trips from 10/81 to 2/82 were at
night and covered a relatively small portion of the inner
boulder field.

Middle Cove

Middle Cove contains the next largest intertidal area
of Cape Arago, and, like North Cove, contains a mixture
of sandstone bedrock, boulders, and outcrops of varying
size. However, Middle Cove is more exposed to surf and
possesses a number of invertebrates rare or absent in the
North Cove inner boulder field. Among these are the hy-
drocoral Allopora porphyra (Fisher, 1931), the coral-like
ectoproct Heteropora alaskensis Borg, 1933, and the soli-
tary coral Balanophyllia elegans Verrill, 1864. An unde-
scribed white alcyonacean octocoral (see T7itonia festiva)
is abundant. Where sea urchins are sparse, Middle Cove
supports diverse and luxuriant invertebrate and algal
communities. Middle Cove appears to possess the highest
hydroid and sponge diversity of any of the coves. In ten
trips here (made in the months of 3, 7, 8/°80; 6, 8/81;
5-8/°83) I found 28 species of opisthobranchs.

South Cove

The west side of South Cove consists of a small boulder
field semi-protected from surf. As one moves toward the
point separating Middle and South coves, surf exposure
increases and the substrate becomes solid rock with deep
surge channels. Not as many species and individuals of
opisthobranchs occur at South Cove. I found 10 species
on five trips (2, 5/’80; 5/’81; 6, 7/'82), and none of the
species was ever abundant. The low number of opistho-
branchs here may be related to the smaller size of the low-
intertidal boulder field—much of the area consists of ur-
chin or Phyllospadix-dominated bedrock. For unknown
reasons, hydroids are rare at South Cove.

Good Witch Cove

This is the most surf-exposed of the coves and is acces-
sible only on the lowest tides when the swell is small. The
substrate consists of pocketed-and-fissured bedrock over-
lain with patches of boulders. Many of these boulders are

J. H. R. Goddard, 1984

relatively barren of organisms—probably the result of
grazing by the large numbers of urchins, limpets, and
chitons present and perhaps also the result of boulder-
overturning by surf. However, the undersides of many
ledges and larger boulders support a rich invertebrate fau-
na. I found 18 opisthobranch species here on six trips (5,
Gy 0;4oy/ 1825.95, 7/783).

METHODS

Opisthobranch prey species were determined by observing
close association of the opisthobranch and its possible prey
in the field and by laboratory observation of feeding. Gut
contents also were occasionally examined.

Observations on egg masses and larval development were
largely restricted to species for which no other data cur-
rently exist. To make these observations, opisthobranchs
were first separated by species into dishes or jars. A newly
laid egg mass was scraped off the side of the container,
examined, and transferred to a separate, labelled jar. The
water in these jars was changed every one or two days,
and all jars were kept in a flowing seawater bath (10 to
17°C). Separated egg masses were examined daily until
veligers had hatched, at which time veliger shell lengths
were measured. All measurements of eggs and veligers
were made with a compound microscope equipped with
an ocular micrometer.

Due to the discontinuity of field observations little can
be concluded about the seasonality of most of the opis-
thobranch species. North Cove was observed in every
month of the year (though continuously only for one year),
and conclusions about seasonality are presented for a few
of the species found there. These should be considered
tentative.

NATURAL HISTORY OBSERVATIONS
Acanthodoris nanaimoensis O’ Donoghue, 1921

This dorid occurred rarely at all four coves. I found a
total of seven specimens ranging in length from 5 to 22
mm in February, May, July, and December.

Adalaria sp.

I found ten specimens of this white dorid, ranging in
length from 4 to 15 mm in March, April, August, and
September at North Cove. Sandra Millen (personal com-
munication) informs me that this is one of three Adalaria
species found in British Columbia and is not species 138
in BEHRENS (1980). She further states: “It can be recog-
nized by the elongate body, wider at the front end, and
by the spicules which project out of the top of the tubercles
in a radiating pattern.”

Five Adalaria sp. were found on the anascan bryozoan
Hincksina minuscula (Hincks, 1882) on the undersides of
boulders. Laboratory observations confirmed that Adalaria
sp. feeds on this bryozoan. Members of the Onchidoridi-

Page 145

dae are known to use the radula to open the frontal mem-
branes or opercula of their bryozoan prey and then to use
a muscular buccal diverticulum as a pump to suck out the
zooids (THOMPSON, 1976). After placing fresh pieces of
Hincksina minuscula with Adalaria sp. specimens for a day,
such feeding was evidenced by the many empty zooecia
possessing partially attached frontal membranes.

The egg mass of Adalaria sp. is a white ribbon laid on
edge in a coil of 2 to 4 turns. Egg masses are 1-2 mm
high and 4-10 mm in diameter. For data on the larval
development of this and other species see Table 1.

Aeolidia papillosa (Linnaeus, 1761)

This eolid is frequent at North Cove. Specimens ranged
in length from 5 to 55 mm and often occurred next to
Epiactis prolifera Verrill, 1869, an abundant anemone upon
which Aeolidia papillosa readily feeds in the laboratory
(personal observation).

Aldisa coopert Robilliard & Baba, 1972

I found three specimens, one at Middle Cove in June
1981, and two at Good Witch Cove in May and July
1983. The first two were 22 mm and 27 mm long respec-
tively and orange-yellow in color; they had, respectively,
9 and 8 small black spots on the midline of the dorsum
between the rhinophores and gills. The third specimen
was yellow and also possessed a number of small black
spots on the midline.

Aldisa cooperi was originally described as a subspecies
of Aldisa sanguinea. However, BERTSCH & JOHNSON
(1982), on the basis of sympatry, and Millen (personal
communication), on the basis of anatomy, consider them
to be separate species. With this in mind, I kept one spec-
imen of both species together in a jar to see if mating and
egg-laying would occur. The specimen of A. cooper: mea-
sured 27 mm in length, and that of A. sanguinea 20 mm.
After one month in captivity (12-16°C), and what ap-
peared to be a number of matings, the specimen of A.
sanguinea laid an egg mass. The embryos stopped devel-
oping at about the 32-cell stage. Although I cannot rule
out other factors, this may indicate that interbreeding oc-
curred but resulted in inviable hybrid embryos, thus sup-
porting the conclusion that A. cooper: and A. sanguinea are
distinct species.

Aldisa sanguinea (Cooper, 1863)

One bright-red specimen, 26 mm long and lacking dark
spots on the dorsum, was collected at North Cove by the
spring 1982 Oregon Institute of Marine Biology inverte-
brate zoology class. I found another specimen, red-orange
in color, 20 mm long, and also lacking dark spots, at Good
Witch Cove in May 1983. Specimens of Aldisa sanguinea
reported from Cape Arago by SOWELL (1949) were red-
orange and also lacked dark spots.

Though of weak taxonomic utility, color pattern is the

Page 146

only character I have used to distinguish Aldisa sanguinea
from Aldisa cooperi. Aldisa cooperi is yellow to orange and
apparently always has small black spots on the midline of
the dorsum (ROBILLIARD & BaBA, 1972; BEHRENS, 1980);
A. sanguinea is red, occasionally yellow-orange to yellow-
green, with zero to two relatively large dark spots on the
dorsal midline (MCDONALD & NYBAKKEN, 1980). If spec-
imens of A. cooper: are found that lack any dark spots,
then the identification of the above Cape Arago specimens
as A. sanguinea will become questionable. More work is
clearly needed on these two species. Unfortunately, all I
possess of the two specimens of A. sanguinea I saw is the
radula from the 26 mm specimen.

Ancula pacifica MacFarland, 1905

This species is frequent at North Cove and was most
common during spring and early summer. Ancula pacifica
usually occurred under boulders, and in June 1983 I found
eight specimens with egg masses among the entoproct Ba-
rentsia sp. on the undersides of boulders. Many of these
Barentsia lacked a calyx—most likely as a result of grazing
by Ancula pacifica. Ancula pacifica is known to feed on
Barentsia ramosa (Robertson, 1900) in California
(McDONALD & NYBAKKEN, 1978).

Before spring 1983, all the Ancula pacifica I had ob-
served at Cape Arago had the color pattern described by
ROBILLIARD (1971b) for the two specimens he found in
Washington. These specimens lack orange lines on the
body but do possess orange-tipped rhinophores, accessory
rhinophore papillae, gills, and extrabranchial papillae. In
spring and summer 1983 I noticed the above form of An-
cula pacifica as well as the more typical form (which has
orange lines on the body and is common in California) at
North Cove. Northern and southern forms of Ancula pa-
cifica may exist.

The egg mass of Ancula pacifica is a white, slightly
flattened, tapering cord. The cord is not laid in a spiral.

Anisodoris lentiginosa Millen, 1982

On 18 May 1980 I found one specimen crawling on
bare rock in a pool at Good Witch Cove. It was about 90
mm long, pale yellow in color, and had six small, dark
brown blotches scattered on the central part of the anterior
two-thirds of the dorsum (Figure 2). This specimen rep-
resents a southern range extension of 615 km and is the
first intertidal record of the species (MILLEN, 1982).

Anisodoris nobilis (MacFarland, 1905)

Anisodoris nobilis is moderately common at Cape Arago,
occurs at all four coves, and can be found all year long at
North Cove. I observed specimens less than 10 mm long
in December and April. One March specimen measured
about 200 mm in length. In the field A. nobilis was found
feeding on the yellow sponges Mycale macginitiei de Lau-

The Veliger, Vol. 27, No. 2

benfels, 1930, Zygherpe hyaloderma de Laubenfels, 1932,
Tedania gurjanovae Koltun, 1958, and Lissodendoryx firma
(Lambe, 1895). Anisodoris nobilis readily feeds on these
sponges in the laboratory, and three individuals also ate
Ophlitaspongia pennata (Lambe, 1895) in the laboratory.
Tedania gurjanovae and Ophlitaspongia pennata are new
food records for A. nobilis (MCDONALD & NyYBAKKEN,
1978; BLooM, 1981).

On 30 April 1982 I found one Anisodoris nobilis about
50 mm long under a boulder feeding on an individual of
Lissodendoryx firma covering an area of 680 cm? (total
boulder undersurface = 4900 cm’). Some of the sponge
had already been grazed off the rock. On 21 August 1982
only a few square centimeters of the sponge remained and
no individuals of A. nobilis (nor any other possible pred-
ators of the sponge) were present. Though I cannot rule
out that other A. nobilis or other predators of L. firma had
visited the rock, it is possible that the above specimen of
A. nobilis ate all of the missing sponge.

By area covered, Zygherpe hyaloderma is the most abun-
dant of the yellow sponges at North Cove (personal ob-
servation). Mycale macginitier, which covers considerably
less area (but is a thicker sponge) is next most common.
Preliminary observations suggest that Anzsodoris nobilis
prefers Mycale macginitier over Zygherpe hyaloderma but
will sometimes eat the first of these sponges it contacts,
even when the two are in close proximity. Further study
of the food preferences of Anisodoris nobilis and the effects
of length of starvation, previous diet, and age would be
interesting.

The ribbon of one egg mass laid by a 140-mm long
individual measured 2.7 x 40 cm and contained about 2.1
million eggs.

Aplysiopsis smithi (Marcus, 1961)

This sacoglossan occurred in a few high-intertidal pools
between South and Good Witch coves. I examined these
pools for Aplysiopsis smithi monthly from June 1980
through July 1981. The sacoglossan and its egg masses
were abundant in late spring and early summer 1980,
and, with the exception of one specimen found in Decem-
ber 1980, disappeared in September 1980 and did not
reappear until May 1981. It was abundant until at least
July 1981, though not as common as in the previous year.
In these pools A. smithi feeds exclusively on the green alga
Cladophora sp. GREENE (1970) reported southern Cali-
fornia A. smithi feeding on Cladophora trichotoma.

My observations of the egg masses and veligers match
those of GREENE (1968). He observed white and yellow
colored egg masses. I noticed that laboratory specimens
laid yellow egg masses at first, but later egg masses were
faint yellow to white. The newly hatched planktotrophic
veligers lack eyespots and possess a granular black pig-
ment scattered on the edge of the mantle that folds over
the outer lip of the shell. Such pigmentation is unique
among the veligers observed in this study.

J. H. R. Goddard, 1984

Archidoris montereyensis (Cooper, 1863)

Archidoris montereyensis is fairly common at Cape Ar-
ago and occurs year-round. Specimens ranged in length
from 4 to 65 mm. Individuals less than 10 mm long were
found from November to April, and individuals greater
than 50 mm were observed in December, January, April,
May, and July. Eggs were observed in the field in May
and July. I sometimes found A. montereyensis stranded
out of water next to or on Halichondria panicea (Pallas,
1766) and on the massive and densely spiculate sponge
Suberites sp. One specimen, 10 mm long, was found at
Good Witch Cove embedded in a soft, unidentified, or-
ange, encrusting sponge.

Archidoris odhnerit (MacFarland, 1966)

This species is quite common at Good Witch and Mid-
dle coves but also occasionally occurs at North and South
coves. With the exception of one 13 mm long specimen
found in June 1983 at North Cove, all specimens were
70-100 mm long. Archidoris odhneri rarely occurred on
sponges. Two specimens, including the above 13 mm in-
dividual, were on Hymeniacidon ungodon de Laubenfels,
1932, and ate this sponge in the laboratory. One 90-mm
long specimen, brownish-yellow in color (and the only
specimen of A. odhner: I found that was not pure white),
was found on a large Suberites sp. individual of the same
color; the sponge appeared to have been grazed. Archidoris
odhnert has not been reported feeding on either of these
sponges (McDONALD & NYBAKKEN, 1978; BLOOM,
1981).

Berthella californica (Dall, 1900)

This pleurobranchomorph is common on the sub-
merged, relatively barren boulders at Good Witch Cove
and also occurs occasionally at the other three coves. BEH-
RENS (1980) considers Pleurobranchus denticulatus
MacFarland, 1966 to be synonymous with Berthella cali-
jornica and gives Crescent City, California as the northern
range limit of B. californica. However, LAMBERT (1976)
reported Pleurobranchus denticulatus from Pearse Island,
British Columbia.

The egg mass of Berthella californica is a white ribbon,
3-4 mm wide, laid on edge in a loose spiral. The newly
hatched veligers are distinctive in possessing a dark, red
wine colored patch of tissue on the right side next to the
anus, as well as a shell whose oldest portion has a brown
tinge (similar to the pigmentation on the veliger shells of
Hallaxa chani, but not as dark or extensive).

Cadlina luteomarginata MacFarland, 1966

This species is moderately common at all the coves of
Cape Arago. I occasionally found it feeding on the pink
sponge Aplysilla glacialis (Dybowski, 1880). This sponge
has previously been reported as the food of Cadlina flavo-

Page 147

maculata MacFarland, 1905, and C. modesta, but not C.
luteomarginata (MCDONALD & NYBAKKEN, 1978). One
individual was found feeding on a light grayish-tan col-
ored A. glacialis individual, and a number of C. luteomar-
ginata starved in the laboratory fed on Halisarca sp. One
specimen, 23 mm long at collection, has survived seven
months in the laboratory without any food except for one
day of feeding on Aplysilla glacialis one month after col-
lection.

On 1 May 1982 I noted a specimen of Aplysilla glacialis
covering an area of 126 cm? on the underside of a North
Cove boulder. The boulder had 630 cm? of undersurface.
I tagged the boulder to keep track of the sponge. On 21
August 1982 one 27 mm specimen of Cadlina luteomar-
ginata and a 15 mm Cadlina modesta were observed feed-
ing on this Aplysilla. They had eaten 18 cm? of the sponge,
but the sponge had grown an approximately equal amount
since May. On 26 March 1983 both slugs were still pres-
ent (though I cannot rule out that they were different
individuals or that additional individuals of Cadlina had
visited the rock) and had eaten all but 4.5 cm? of the
sponge. The C. luteomarginata measured 42 mm and had
laid two egg masses (one recently laid; the larvae of the
other had already hatched). The C. modesta measured 20
mm. On 15 April 1983 both dorids were gone and only a
trace of Aplysilla remained.

O’ DONOGHUE & O’ DONOGHUE (1922:138) stated that
the egg masses of Cadlina luteomarginata “were not found
so frequently as those of Archidoris montereyensis and
Diaulula sandiegensis although the animal itself is quite
common,” and CosTELLo (1938:331) noted that “the egg
ribbons are less vertical than in ... other forms.” My
observations agree with both statements. I saw only two
egg masses in the field, both in March 1983. The white
egg mass ribbon slants toward the center of the tightly
wound coil and overlaps itself in the preceding turn. One
egg mass had five turns and a diameter of 16 mm. DEHNEL
& Konc (1979) described aspects of the egg mass of Cad-
lina luteomarginata but did not mention the angle of the
ribbon or tightness of the coil. Egg masses of C. luteomar-
ginata may be more common subtidally than intertidally.

Cadlina modesta MacFarland, 1966

Before April 1982 I had only seen two specimens of
Cadlina modesta at Cape Arago. After April 1982 I found
15 specimens. All 17 specimens were observed in spring
and summer at North Cove. Two individuals were feeding
on Aplysilla glacialis and two on Halisarca sp., a previously
unreported sponge prey. One individual, 6 mm long and
found on Halisarca sp., survived in, the laboratory at 8-
16°C for 17.2 months. This specimen was sporadically fed
Halisarca sp. for the first 5 months, and grew to 20 mm
in length. It was then starved for 6 months. During the
following 6 months it was again sporadically given Hall-
sarca sp., and it ate a total of 13 cm? of the sponge (Hal-
isarca sp. averages 2 to 3 mm in thickness). The specimen

Page 148

did not appear to eat any of the Halisarca sp. present for
the last month of its life, and it never laid eggs.

Concerning the color of the rhinophores of Cadlina mo-
desta, MACFARLAND (1966) wrote “rhinophores light, sel-
dom dusky,” and BERTSCH (1969) stated “the color of the
rhinophores varied from whitish to dusky brown.” In lab-
oratory specimens of Cadlina modesta the rhinophores
changed from whitish or light yellow to brown with in-
creasing age.

The egg mass of Cadlina modesta is a cream colored
ribbon 2-3 mm high laid in a loose spiral of 1 to 3 turns.
Mean egg mass area was 115.3 mm? (SD = 52.0, n= 13
egg masses laid in laboratory by three specimens 15-20
mm long). At a mean density of 180 eggs per mm? of egg
mass (SD = 33, n = 3), the “average” egg mass of Cadlina
modesta contains about 20,750 eggs.

Catriona columbiana (O’ Donoghue, 1922)

Catriona columbiana is frequent at Cape Arago and was
usually on, or near, the stolons of Tubularia marina (Tor-
rey, 1902) on which it feeds. Catriona columbiana appears
to be most abundant in spring and summer, particularly
at North and Middle coves. Two color forms exist, one
with orange cephalic tentacles and one with white cephalic
tentacles (both forms have orange on the distal half of the
rhinophores). I did not observe any differences in the rad-
ula, mandibles, egg masses, or veligers of these two forms.

This species lays small, sac- to crescent-shaped egg
masses (type D of Hurst, 1967). There is one egg per
capsule, and the capsules are deposited in an irregular
coil, 2-3 capsules wide, in the egg mass.

Crimora coneja Marcus, 1961

With the exception of a single specimen reported from
“near Humboldt Bay, Humboldt County, California”
(McDONALD, 1983), this delicate and rare dorid was pre-
viously known only from the type locality of Point Loma,
San Diego County, California (BEHRENS, 1980; Mc-
DONALD, 1983). On August 29, 1981 Katheryn Young
and Tom Wayne of O.I.M.B. collected two individuals
from under a boulder in the North Cove inner boulder
field (Figure 3). Both specimens were 16 mm long. Since
then I have observed seven specimens, ranging in length
from 14 to 19 mm, at North Cove (one in December 1981,
one in April 1983, two in August 1983, and three in
September 1983) and one 12 mm specimen at Middle
Cove in July 1983. These eight specimens were on Hinck-
sina minuscula on the undersides of boulders approxi-
mately 0.3 m in diameter.

Laboratory observations confirmed that Crimora coneja
feeds on FHincksina minuscula. One individual overnight
ate almost every zooid in a 1 cm? piece of the bryozoan.
The zooecia were empty and the frontal membranes miss-
ing, indicating that Crimora uses its radula to rasp out
entire zooids (in contrast to the feeding method of Adalaria

sp.).

The Veliger; Volk 27, Now?

The egg mass of Crimora coneja is a thin ribbon laid
flat (not on edge as in most dorids) in a spiral of 4 to 6
turns, and measures 9-12 mm in diameter. The ribbon is
about 1 mm wide, contains 1-2 layers of eggs and lacks
striations of any sort. In different egg masses the eggs vary
from white to pale orange in color. Because of its thinness
and form, the egg mass is difficult to discern when laid
on bryozoan-encrusted substrates.

Cuthona abronia (MacFarland, 1966)

This eolid can be common during the spring and sum-
mer at North and Middle coves. Although occasionally
seen crawling on submerged algae or on the surface of
calm tidepools, it usually occurs among minute, uniden-
tified, thecate hydroids under boulders in areas subject to
little accumulation of silt and detritus (purple sea urchins
are often in the vicinity). In April 1982 I found five spec-
imens and about 20 egg masses on the underside of a
single small boulder. :

Cuthona albocrusta (MacFarland, 1966)

Cuthona albocrusta occurred at Middle Cove (two spec-
imens in August 1980 and four in July 1983) and North
Cove (five in May 1980, one in July 1981, and over 11
in July and August 1983). In August 1983 I found five
specimens clustered among minute, unidentified, un- -
branched, thecate hydroids (probably of the family Cam-
panulinidae). These hydroids were partially covered by a
fine, light grayish-tan colored silt. The eolids were quite
cryptic in this microhabitat.

Cuthona cocoachroma Williams & Gosliner, 1979

Three specimens of this rare eolid were seen at Middle
Cove, one in July 1980, one in June 1981, and one in
June 1983. The range of Cuthona cocoachroma is extended
255 km from Trinidad Head, Humboldt County, Cali-
fornia (JAECKLE, 1981). I also found one specimen of C.
cocoachroma at Cape Blanco (50 km south of Cape Arago)
in April 1982.

The egg mass of Cuthona cocoachroma is a white cord
laid in a small rosette.

Cuthona flavovulta (MacFarland, 1966) ~

I found seven specimens crawling on submerged algae
or on the surface of calm pools at Middle and North coves
in summer 1983. The range of Cuthona flavovulta is thus
extended from Palmer’s Point, Humboldt County, Cali-

‘fornia (JAECKLE, 1981). :

Cuthona fulgens (MacFarland, 1966)

Four specimens were found crawling on submerged al-
gae or on the surface of calm pools at North and Middle
coves in summer 1983. The range of Cuthona fulgens is

J. H. R. Goddard, 1984

extended from Duxbury Reef, California (GOSLINER &
WILLIAMS, 1970).

Dendronotus frondosus (Ascanius, 1774)

I observed few Dendronotus frondosus at Cape Arago
until June and July 1983, when over 20 specimens were
seen on a small unidentified species of Obelia in the very
low intertidal of Middle Cove. Dendronotus frondosus can
be abundant during the spring and summer, feeding on
the much larger and highly branched species of Obelia on
the docks of the Charleston boat basin (personal obser-
vations). All Cape Arago specimens were less than 20 mm
long, and a number of individuals were on hydroids grow-
ing on the brown alga Cystoseira. Dendronotus frondosus
occurred in low numbers at all the coves of Cape Arago.

Dendronotus subramosus MacFarland, 1966

I found only two specimens of Dendronotus subramosus
at Cape Arago, both at Middle Cove. One specimen, 4
mm long, was under a small boulder, and one 2 mm
specimen was on hydroid-covered Cystosezra.

Diaphana californica Dall, 1919

One specimen, with a 3-mm long shell, of this minute

bullomorph was collected from the North Cove inner
boulder field in August 1981. I found three more (shell

lengths of 3.3 mm, 3.0 mm, and 2.1 mm) in the same
location in September 1983. Much of the mantle and vis-
cera is visible through the thin translucent shell. The range
of this species is extended 610 km from Duxbury Reef,
California (GOSLINER & WILLIAMS, 1970).

The egg mass of Diaphana californica is a fragile and
very extensible cord attached to the substrate along its
entire length. The cord of one egg mass was laid straight,
varied from 0.1 to 0.5 mm in diameter, and measured 20
mm in length. Two other egg masses were C-shaped, with
the cord varying from 0.75 to 1.5 mm in diameter; one of
these was 7 mm long, the other 10 mm.

Diaulula sandiegensis (Cooper, 1863)

This species is moderately common at Cape Arago and
is often seen under ledges and boulders feeding on Hali-
clona sp. A of SMITH & CARLTON (1975:45). Specimens
ranged in size from 5 to 70 mm. Specimens less than 15
mm were found in January, March, April, June, and
July, and specimens over 50 mm long were found in May
through July, and in October and January. Small to me-
dium size individuals are often at the end of a “‘path” they

have eaten into Haliclona sp. and, due to the resemblance -

of their dorsal brown rings or spots to the oscula of the
sponge, are quite cryptic. One 40 mm specimen was found
in April at North Cove feeding on a buff colored, encrust-
ing species of Sigmadocia. This is a new food record for
Diaulula sandiegensis (MCDONALD & NYBAKKEN, 1978;
BLoom, 1981).

Page 149

Dirona albolineata Cockerell & Eliot, 1905

This species was abundant at North Cove during the
latter part of summer in 1980, 1981, and 1982. It was
rare or absent in the other seasons I looked. In 1983 I did
not see any until early September, when only two were
found. Dirona albolineata is usually observed crawling on
algae and rocks in pools along with Janolus fuscus and
Triopha catalinae.

Discodoris heathi MacFarland, 1905

I found five specimens ranging in size from 7 to 90 mm
during the summer months at North Cove, and one 20
mm individual in August at Middle Cove. An 11 mm
specimen found embedded in Mycale macginitier under a
boulder ate this sponge in the laboratory. A 60 mm slug
ate a 30 mm diameter Mycale macginitier overnight. Dis-
codoris heathi has been reported feeding on a number of
species of Mycale but not Mycale macginitier (MCDONALD
& NYBAKKEN, 1978; BLOOM, 1981).

Discodoris heathi lays large yellow egg masses in the
typical dorid form.

Doto amyra Marcus, 1961

I observed this species only at Middle Cove: one spec-
imen in July 1980, five in June 1981, and 22 (with egg
masses) in May and July 1983.

Despite the taxonomic confusion surrounding eastern
Pacific Doto species (Marcus, 1961 described four new
species, but BEHRENS, 1980 and McDONALD &
NYBAKKEN, 1980 list only two of those), I am calling this
species Doto amyra after MCDONALD & NYBAKKEN (1980).
With the exception of one, all the specimens I examined
matched their description and photograph of Doto amyra
(Marcus’s original description mentions little about the
living animal). The cerata cores varied from light yellow
to light orange-brown; the gonads were yellow, and the
cerata tubercles were translucent white and contained
slightly opaque white grains (these grains are larger and
less dense than the opaque white grains present in the
distal parts of the rhinophores and their sheaths). The
exceptional specimen mentioned above, while possessing
all the above characteristics, also possessed a subcutaneous
black pigment in the body similar to that in the body of
Doto kya. However, this slug laid eggs identical to those
of the other specimens of Doto amyra, and, as indicated
below, the eggs of Doto amyra are very different from those
of Doto kya.

Most of the specimens of Doto amyra, and all of the egg
masses, were on colonies of the thecate hydroid Abietinaria
sp., a previously reported prey of Doto amyra (BEEMAN &
WILLIAMS, 1980). Slugs occurred on both the stolons and
upright portions of the hydroid. Egg masses were usually
attached to the bases of the colonies.

Doto amyra feeds on Abietinaria sp. by rasping a circular
hole in the perisarc with its radula and then sucking out

Page 150

the hydroid tissues by means of muscular contractions of
its esophagus (personal observations). One 5 mm long slug
rasped a hole 32 wm in diameter in the perisarc.

Doto amyra lays yellowish egg masses that are laterally
flattened, slightly crescent-shaped with rounded ends, and
laid on edge. The thick jelly attachment sheet is translu-
cent white with parallel white striations; the rest of the
egg mass jelly is clear. Egg masses measure up to 1.5 mm
high by 4 mm long and derive their yellow color from the
yellow eggs.

The larvae of Doto amyra hatch out as crawling veligers
possessing large eyespots, a large foot, a small velum, and
poor swimming abilities. In the presence of Abzetinaria
sp., they metamorphose into juvenile slugs within a few
days after hatching (personal observation). Doto amyra is
the first eastern Pacific nudibranch known to produce leci-
thotrophic larvae (type 2 development of THOMPSON, 1967)
(Hurst, 1967; THOMPSON, 1967; BONAR, 1978; present
study). I will examine this development more closely else-
where (ms in preparation).

Doto kya Marcus, 1961

In May and June 1980 I found four specimens at North
Cove. Two of these were among Plumularia sp. and a
short unidentified hydroid of the family Campanulinidae.
Both hydroids were growing on the perennial portion of
the brown alga Cystoserra. Three more were seen at Mid-
dle Cove in July 1983. All specimens match the photo-
graph of Doto kya in BEHRENS (1980).

The white egg masses of Doto kya are laterally flattened
(more flattened than the egg masses of Doto amyra), slight-
ly wavy or folded crescents to semi-circles; they are laid
on edge and measure up to 3 mm in length.

Eubranchus olivaceus (O’Donoghue, 1922)

Two specimens, 6 mm and 8 mm long, were found at
North Cove in June and July 1983. The radula from the
latter has 42 rows of teeth and does not taper. As MARCUS
(1961:49) noted, the nontapering radula is at present the
major anatomical character distinguishing L. olivaceus from
E. rustyus.

Eubranchus rustyus (Marcus, 1961)

I found a few Eubranchus rustyus in the summer months

The Veliger; Vols 27 onzZ

at North and Middle coves. Six specimens 0.5-5 mm long
occurred with egg masses on Plumularia sp. at Middle
Cove in July 1983. Eubranchus rustyus eats this hydroid
in the laboratory (personal observation). The radula from
a 6-mm long specimen has 57 rows of teeth and tapers
distinctly.

Flabellina trilineata (O’Donoghue, 1921)

Flabellina trilineata is the most abundant eolid at Cape
Arago and occurs at all four coves. It is commonly found
feeding on 7ubularia marina, an abundant hydroid at Cape
Arago. Both species appear to be most abundant during
the spring. I have observed F. trilineata feeding on Euden-
drium californicum Torrey, 1902, in California, and
McDOoNALD & NYBAKKEN (1978) report it feeding on
Eudendrium sp. Although large Eudendrium californicum
colonies occur at Middle Cove, often in close proximity to
F. trilineata and Tubularia marina, I never observed the
eolid on them. This suggests that F. trilineata prefers Tub-
ularia marina to Eudendrium californicum.

Many individuals of F. trilineata lacked orange pigment
on the rhinophores and cephalic tentacles. MACFARLAND
(1966:321) also noted this variability in color pattern.

Hallaxa chani Gosliner & Williams, 1975

Since first reporting two specimens of Hallaxa chani
from North Cove, Cape Arago (GODDARD, 1981), I have
seen over 70 individuals in the North Cove inner boulder
field, and as many as 14 specimens on a single low tide.
Hallaxa chani is usually on or near its sponge prey Hali-
sarca sp. underneath mid- to low-intertidal boulders (Fig-
ures 4, 5).

In the laboratory, specimens of Hallaxa chani of all sizes
readily feed on Halisarca sp. and do not feed on the white
colonial tunicate (either Didemnum carnulentum Ritter &
Forsyth, 1917, or T7rididemnum opacum [Ritter, 1907])
that is common under North Cove boulders and was pre-
viously suspected to be eaten by HZ. chani (see GODDARD,
1981). I have never observed H. chani feeding on any other
organisms.

Hallaxa chani blends well with Halisarca sp. (Figures
4,5). Both organisms are light to yellowish-tan in color,
and the reddish-brown flecks and subcutaneous dark spots
on H. chani match the dark spots on Halisarca sp. (The

Explanation of Figures 2 to 6

Figure 2. Anisodoris lentiginosa, about 90 mm long, found at
Good Witch Cove on 18 May 1980.

Figure 3. Crimora coneja, 16 mm long, found at North Cove on
29 August 1981 by Katheryn Young and Tom Wayne.

Figure 4. Hallaxa chani, about 20 mm long, on Halisarca sp. on
the underside of a North Cove boulder. 28 April 1982. Note the
matching color pattern of the dorid and the sponge. The sur-
rounding white organism is the colonial tunicate Didemnum car-
nulentum.

Figure 5. Hallaxa chani, about 18 mm long, on Halisarca sp.
(center) on the underside of a North Cove boulder. 28 April
1982.

Figure 6. Same spot as in Figure 5, 13 days later. The specimen
of Hallaxa chani in Figure 5 has eaten all of the Halisarca sp.,
deposited an egg mass, and moved on. 11 May 1982. The small
egg mass above the egg mass of Hallaxa chani was laid by Ros-
tanga pulchra. The sponge in the lower portion of this photo-
graph is Lissodendoryx firma; it was subsequently eaten by An-
isodoris nobilis (see text on A. nobilis).

J. H. R. Goddard, 1984

Page 152

“dark spots” on Halisarca sp. are caused by the sponge
structure rather than pigmentation. They appear to be
associated with the water canal system.) Moreover, when
feeding, H. chani tends to spread out its semi-translucent
dorsum, thus taking on some of the sponge color and also
making the thin edge of the dorsum difficult to discern.
Small H. chani are very cryptic.

Observations indicate that Hallaxa chani grows rapidly
for a dorid of its size, reaches maturity in a few months,
and lives approximately six months. One individual, 5
mm long (wet weight of 20 mg) at collection, kept in 10°C
water and given Halisarca sp. every few weeks, grew to a
wet weight of 360 mg in 44 days, and laid an egg mass
44 days after collection. It weighed 121 mg on day 132,
and was moribund after 152 days. Four other specimens
of similar initial weight (including one that was kept iso-
lated and never laid eggs but which reached a length of
28 mm and a weight of 957 mg) lived 150 days or less
under similar conditions.

The egg mass of Hallaxa chani is a cream colored ribbon
2-3 mm high laid in a loose spiral of 1 to 3 turns (Figure
6). The hatching veligers lack eyespots and possess type
1 shells whose oldest portion is a translucent brown color.
Specimens of 1. chan: less than 5 mm long occurred in
all seasons, and egg masses were found in all seasons
except winter, indicating that reproduction occurs most of
the year.

Hermaea vancouverensis O’ Donoghue, 1924

I found four specimens, 6-8 mm long, of this sacoglos-
san on brown algae in the North Cove inner boulder field
in June 1981.

Hermissenda crassicornis (Eschscholtz, 1831)

Hermissenda crassicornis was not very common at Cape
Arago. In June 1981 I found over 20 specimens at Middle
Cove, but on other occasions never more than six. Inter-
estingly, Hl. crassicornis is abundant on the docks of the
Charleston boat basin during spring and summer. Most
of the H. crassicornis individuals at Cape Arago and the
boat basin are the variety possessing a bluish-white stripe
on the cerata (see BEHRENS, 1980:93, lower photograph).
Hermissenda crassicornis occurs in all four coves.

Janolus fuscus O’Donoghue, 1924

GOSLINER (1982) recently reinstated /Janolus fuscus as a
distinct species from the more southerly /anolus (Antio-
pella) barbarensis (Cooper, 1863). Cape Arago Janolus are
all Janolus fuscus, and the Antiopella barbarensis reported
from Oregon by SPHON (1972) were undoubtedly also /.
fuscus.

Janolus fuscus occurred from April to October at North

Cove only. During August and September it is one of the

most abundant and conspicuous nudibranchs at North
Cove. It is usually found crawling on rocks or on the algae

The Veliger,. Volt 274 Now

Sargassum and Egregia and the surfgrass Phyllospadix in
the large pools of the inner boulder field where it searches
for the arborescent bryozoans upon which it feeds
(McDONALD & NYBAKKEN, 1978; personal observation).

Laila cockerelli MacFarland, 1905

Laila cockerelli was uncommon at Cape Arago until
spring and summer 1983 when I found a total of 20 spec-
imens at North and Middle coves. It also occurs at South
and Good Witch coves. A number of individuals were
observed on the light orange bryozoan Hincksina velata
(Hincks, 1881) and ate this bryozoan in the laboratory.
Laila cockerellt has been reported feeding on Hincksina
velata in California (MCDONALD & NYBAKKEN, 1978).

My observations of the pink colored egg mass of Laila
cockerelli generally match those of O’DONOGHUE &
O’ DONOGHUE (1922). However, they described it as a
“slightly flattened string . .. woundiin a close, tight-fitting
spiral.” Egg masses I observed were a ribbon laid flat in
a close spiral. It is very similar in morphology to the egg
mass of Crimora coneja. One egg mass had 4.5 turns, a
diameter of 15 mm, and a ribbon whose width varied from
1.5 to 2.0 mm.

Onchidoris muricata (Miller, 1776)

Onchidoris muricata occurred at North Cove only. I ob-
served specimens in spring 1980, from late summer 1981
to early spring 1982, and again in spring 1983. On two
occasions (December 1981 and January 1982) I found
over ten specimens; on all other trips six or fewer were
seen.

Onchidoris muricata usually occurs under boulders on
Eurystomella bilabiata (Hincks, 1884) or Microporella cri-
bosa (Osburn, 1952), two abundant ascophoran bryozoans
which it eats in the laboratory (personal observation).
Onchidoris muricata that have been feeding on Eurysto-
mella bilabiata possess a deep red colored digestive gland
visible through the foot. I also found O. muricata on
Hincksina minuscula but did not confirm feeding on this
species.

Onchidorts muricata can be difficult to distingiush from
Adalaria sp. in the field. However, O. muricata is usually
shorter, rounder, and has bulbous, fairly smooth dorsal
papillae. The pointed spicules in the papillae of O. mum-
cata barely protrude above the surface of the papillae;
those of Adalaria sp. protrude very far.

Hurst (1967) described the egg mass of Onchidoris
muricata. Like many other dorids, O. muricata sometimes
lays only a small portion of an egg coil (personal obser-
vation).

Onchidoris sp. (cf. Onchidoris hystricina)

This species is referred to as Onchidoris hystricina by
BEHRENS (1980:66-67), MCDONALD & NYBAKKEN (1980:

J. H. R. Goddard, 1984

44-45), BEEMAN & WILLIAMS (1980:328), and Mc-
DONALD (1983:198-199). However, Onchidoris sp. dis-
agrees with BERGH’s 1878 and 1880 descriptions of O.
hystricina, as well as Marcus’s (1961) description of O.
hystricina. The dorsal papillae, gills, and radula are very
different (Sandra Millen, personal communication; per-
sonal observation). The species appears to be undescribed.

Onchidoris sp. was observed only at North Cove and
only at the end of summer. I found ten in August 1981,
seven in August and September 1982, and six in August
and September 1983.

The white egg mass of Onchidoris sp. is a cord, 0.75-
1.0 mm in diameter, laid in a disorderly spiral of 1 to 4
turns measuring up to 5 mm in diameter.

Placida dendritica (Alder & Hancock, 1843)

I found this species feeding on Codium fragile in pools
between South and Good Witch coves. BEHRENS (1980)
reports San Francisco Bay as the northern limit of this
species, but LAMBERT (1976) found it on the northern tip
of Vancouver Island, British Columbia.

Polycera atra MacFarland, 1905

Three specimens were observed in September 1983 at
North Cove. Polycera atra occurred by the hundreds feed-
ing on arborescent bryozoans in the Charleston boat basin
in June 1983, but repeated observation in mid-July turned
up only a single specimen. The range of Polycera atra is
extended from Humboldt Bay, California (JAECKLE, 1981).

Precuthona divae Marcus, 1961

This eolid occurred in low numbers at North and Mid-
dle coves in the spring and summer. One specimen from
Middle Cove was 32 mm long. I have also found Precu-
thona dwae at Cape Blanco (50 km south) feeding on the
pink colonies of Hydractinia sp. The egg mass of P. divae
is a round, hemispherical rosette. ROBILLIARD (1971b)
reported egg masses of P. divae from San Juan Island,
Washington, as being white; those at my study sites were
pink.

Rostanga pulchra MacFarland, 1905

Rostanga pulchra is abundant at Cape Arago and occurs
with its egg masses throughout the year. I observed it
feeding on Ophilitaspongia pennata and also found it (and
its eggs) on Antho lithophoenix (de Laubenfels, 1927) and
Hymedesmia sp. A (of SMITH & CARLTON, 1975:51). I
also found R. pulchra close to, but not on, Plocamia ka-
rykina de Laubenfels, 1927, and Axocielita originalis (de
Laubenfels, 1930). Rostanga pulchra has previously been
reported feeding on, or occurring on, all of the above
sponges except for Hymedesmia sp. A (MCDONALD &
NYBAKKEN, 1978).

Page 153

Triopha catalinae (Cooper, 1863)

One of the most common dorids at Cape Arago, Triopha
catalinae occurs year-round but is most abundant during
summer and fall, especially at North Cove. Individuals
ranging in size from less than 10 mm to 70 or 80 mm can
be found in nearly any month; this suggests a long breed-
ing season and a probable lack of synchrony of reproduc-
tion among individuals. I have never seen 7. catalinae egg
masses in the field. Egg masses laid in aquaria are large,
pinkish-white, coiled ribbons laid on edge.

At Cape Arago Triopha catalinae feeds on unidentified
species of arborescent and encrusting bryozoans. Small
individuals are often found on bryozoans on the under-
sides of boulders, and large individuals are usually out in
the open, crawling on submerged algae and rocks.

Triopha maculata MacFarland, 1905

I found five orange specimens during summer 1983 at
North Cove. All were 10-20 mm long, and three were
observed on bryozoans underneath boulders.

Tritonia festiva (Stearns, 1873)

Tritonia festiva occurs at all four coves but is most com-
mon at Middle and Good Witch coves. It usually occurs
on or near a white to salmon colored alcyonacean octocoral
upon which it feeds. SOWELL (1949) also reported finding
T. festiva “on or near” this octocoral but did not confirm
feeding. The octocoral is in the form of low, rounded
colonies up to 15 mm in diameter and is undescribed (F.
M. Bayer, personal communication). Large aggregations
of fairly evenly spaced colonies are common under wave-
exposed, low-intertidal ledges at Cape Arago.

The feeding of 77ztonza festiva on the soft coral is re-
markable. The following description is based on obser-
vations of 20 feeding attacks made by 7. festzva 15-25 mm
long on soft coral colonies 7-10 mm in basal diameter.
While searching for its prey the frontal veil of 7. festiva
is laterally expanded and horizontal. Upon contacting an
expanded colony with the sensitive, slender processes on
its frontal veil (or with its rhinophores), 7. festiva pulls
back its head, slows its crawling, raises the frontal veil,
and begins eversion of its oral canal. The slug crawls
slowly and carefully forward, using the tactile sense of the
frontal veil and oral canal to position the expanded oral
canal over the end of one or a few polyps. Polyps touched
by the frontal veil and oral canal contract their tentacles
but not their stalks. Once positioned, 7. festiva rapidly
thrusts its head forward while extending its buccal mass.
The jaws and radula make a number of strikes in rapid
succession, and one to seven polyps are ripped out of the
colony as the rest of the polyps quickly contract. Ingested
polyps can be seen passing through the esophagus im-
mediately following an attack. 77itonia festiva will not at-
tack contracted colonies, probably because they cannot

Page 154

penetrate the tough and densely spiculate coenenchyme.
Every attack I observed was successful.

This feeding process is similar to that described by
THOMPSON (1976) for Tritonia hombergi Cuvier feeding
on Alcyonium digitatum (Linnaeus) and is also quite sim-
ilar (particularly in the positioning phase) to the feeding
sequence described by WILLOws (1978) for T7ztonia di-
omedea Bergh, 1894, feeding on the sea pen Virgularia sp.
Tritonia hombergi and T. diomedea attain much larger size
than 7. festiva and bite off and ingest pieces of coenen-
chyme and sections of sea pen respectively. I have observed
T. festiva biting off only polyps. Large 7. festiva (or T.
festiva feeding on small colonies) may bite off pieces of
coenenchyme or ingest small colonies.

Tritonia festiva also occurred next to Clavularia sp., a
stoloniferan octocoral that I observed 7. festiva eating in
the laboratory and which has previously been reported as
a prey item of 7° festiva (MCDONALD & NYBAKKEN, 1978).
Tritonia festiva from Cape Arago also attacked specimens
of Gersemia rubiformis (Pallas, 1788) collected from Cape
Blanco as well as an unidentified pink gorgonian dredged
offshore by local fishermen.

The white egg mass of 77ztonia festiva is a flattened
cord laid in a close spiral and attached to the substrate by
a thin, egg-free jelly sheet (type B egg mass of Hurst,
1967). The cord is somewhat convoluted, giving the egg
mass a rosette appearance. Dimensions are: egg mass di-
ameter, 10-20 mm; height, 1 mm; cord diameter, 0.5 mm.
The egg mass is delicate, and the egg capsules are not
embedded in a jelly matrix.

DISCUSSION
Life Cycles

Most of the dorid nudibranchs, and all of the eudori-
daceans, whose life cycles have been studied have been
shown to possess annual life cycles (SWENNEN, 1961; MIL-
LER, 1962; THOMPSON, 1964, 1976; PoTTs, 1970; CLARK,
1975; Topp, 1978, 1979; EysTER & STANCYK, 1981).
Dorids known or suspected to possess subannual life cycles
are generally smaller, bryozoan-feeding members of the
families Corambidae, Goniodorididae, and Polyceridae and
the genus Acanthodoris (SWENNEN, 1961; MILLER, 1962;
CLARK, 1975; PERRON & TURNER, 1977).

Data presented above on the lifespan of Hallaxa chani
strongly suggest that this eudoridacean is subannual.
Combining the observations on lifespan, egg-laying, and
larval development, and assuming a one-month planktonic
existence and one or two months for the juvenile to reach
a length of 5 mm, the generation time appears to be about
four or five months at 10°C. It could be shorter at higher
temperatures.

The relatively rapid growth and short generation time
of Hallaxa chani appear to be adaptations for exploiting
its sponge prey Halisarca sp. A species of Halisarca from
New Zealand grows rapidly compared to most other
sponges and has a generation time of four to five months

The Veliger, Vol. 27-NeeZ

(BERGQUIST, 1978). I observed one group of Halisarca sp.
individuals under a marked boulder at Cape Arago in-
crease in area from 8 cm? to 16 cm? between 29 June 1983
and 7 September 1983 (70 days), and I cannot rule out
the possibility that they were preyed upon during this
period and thus actually grew more. The North Cove
Halisarca sp. population is composed of widely distributed
individuals averaging only a few square centimeters in
area (personal observation). Laboratory and field obser-
vations indicate that specimens of Hallaxa chani are ca-
pable of eating these individuals in a matter of days to
weeks (Figures 5, 6).

It is tempting to postulate that natural selection has
“traded” spicule production in both Halisarca sp. and
Hfallaxa chani for faster growth rates. However, the lack
of spicules in Hallaxa chani may be adaptive primarily in
conferring a textural resemblance to Halisarca sp., helping
to camouflage the dorid from its predators (GODDARD,
1981). Lacking spicules, Halisarca sp. probably has chem-
ical defenses against sponge predators (it does have a pun-
gent odor when torn). Of course, if such defenses do exist
in Halisarca sp., Hallaxa chani and Cadlina modesta have
been able to overcome them and possibly even use them
in their own defense.

Observations on the longevity of Cadlina luteomarginata
and Cadlina modesta suggest that these dorids live at least
a year, and thus possess life cycles similar to those known
for other eudoridaceans. One Cadlina modesta survived a
period of starvation longer (and at higher temperatures)
than the entire lifespan of regularly fed Hallaxa chani.
Although this Cadlina modesta never laid eggs, observa-
tions by THOMPSON (1961), Topp (1978), and EysTER
(1981), as well as the above observations on one Hallaxa
chani that never laid eggs, all indicate that lack of repro-
duction can result in larger size, but does not significantly
affect lifespan.

Development

Data on the larval development of Cape Arago opis-
thobranchs are summarized in Table 1. Aplysiopsis smithi,
Onchidoris muricata, and Triopha catalinae are the only
species in this table whose development has previously
been examined (Hurst, 1967; GREENE, 1968; BEEMAN &
WILLIAMS, 1980).

The development times, egg and veliger sizes, and the
production of veligers that lack a propodium, usually lack
eyespots, and possess a mantle fold that attaches inter-
mittently to the shell lip all indicate that, with the excep-
tion of Doto amyra, every species in Table 1 produces
planktotrophic veliger larvae (type 1 development of
THOMPSON, 1967) (THOMPSON, 1967, 1976). As men-
tioned previously, Doto amyra produces lecithotrophic ve-
ligers (type 2 development).

Of the 20 species in Table 1 that produce planktotroph-
ic larvae, four (20%) produce veligers possessing eyespots
at hatching. This is rather high considering that the ve-

J. H. R. Goddard, 1984

Larval development of Cape Arago opisthobranchs.

Diameter of ova (um)

Table

1

Page 155

Ova per
Species Range’ Month? N? capsule
Adalaria sp. 81.2-83.7 April 3 1
Ancula pacifica 58.3-59.0 June 2 1
Anisodoris nobilis 83.0 June 1 up to 20
Aplysiopsis smithi 66.0 July 1 1
Berthella californica 92.6 May 1 1-2
Cadlina modesta 91.0-92.0 April 3 1
Catriona columbiana 99.7 July 1 1
Crimora coneja 71.6-74.2 April 3 1
Cuthona cocoachroma 96.3 July 1 1
Diaphana californica TL Sept. 1 1
Discodoris heath 76.8 June 1 4-7
Doto amyra 149.6-154.3 May 4 1
Doto kya 1/5) July 1 1
Eubranchus rustyus 92.9 July 1 1
Hallaxa chan 79.6-82.6 May 4 1
Laila cockerelli 95.4 April 1 1
Onchidoris muricata 75.0-77.3 April 2 1
Onchidoris sp. 62.6-64.0 Sept. 4 1
Precuthona divae 107.1 July 1 1
Triopha catalinae — Aug 1
Tritonia festiva 78.9 June 1 1

Eye-

Elo Length of veliger ee
onic Culture sHelle(qan) at

period temp. Shell z hatch-
(days) (°C) type* Range’ N*? ing
11 10-12 1 136.0-143.5 3 no
9 14-16 1 103.8 1 no
14 14-17 1 152.8 1 no
1 15-17 1 112.9 1 no
18 11-14 1 152.7 1 yes
16-19 12-15 1 155.6-158.4 4 no
10 15-17 2 273.9 1 yes
17-18 10-14 1 115.5-123.5 3 no
6 15-17 2 256.7 1 no
7-8 12-16 1 122.1-123.6 2 no
15 14-17 1 144.8 1 no
19-21 15-17 1 236.0-238.5 2 yes
i 15-17 1 122.3 1 no
6 15-17 2 240.1 1 yes
15-17 11-15 1 147.9-154.1 3 no
17 10-13 1 141.8 1 no
10-11 7-11 1 128.5-135.6 3 no
9-11 12-16 1 113.3-116.6 4 no
8 15-17 y} 249.1 1 no
10 14-18 1 ~130 1 no
12 14-17 1 125 1 yes

‘Range of means. Means calculated from measurements (usually ten) of ova (or veliger shells) from a single egg mass.

2 Month in which egg masses laid.

> N = number of egg masses in which ova (or veliger shell lengths) were measured.

*See Hurst (1967).
> Length = longest dimension of shell.

ligers of only one of the 30 northeastern Pacific opistho-
branchs studied by Hurst (1967) has eyespots at hatching
and the statement by THOMPSON (1976) that hatching
planktotrophic veligers usually lack eyespots. Plankto-
trophic veligers develop eyespots before metamorphosis,
and species with lecithotrophic or direct development al-
ways possess eyespots at hatching (THOMPSON, 1976). As
BONAR (1978:187) states “the eyes ... usually develop
rather late in embryogenesis, and along with the appear-
ance of an enlarged propodium signal the approach of
metamorphic competence.” It thus seems likely that the
above four species will be found to possess relatively short
obligatory planktonic stages compared to many other
species with planktotrophic larvae.

The data in Table 1 generally support ‘THOMPSON’s
(1976:86) generalization that ‘within development-type
1, species with the largest eggs have a longer embryonic
period, and, moreover, give rise to larger veliger larvae.”

Food, Competition, and Aggression

Although most nudibranch species are known to eat a
number of prey species (THOMPSON, 1964, 1976; Mc-
DONALD & NYBAKKEN, 1978), a few species appear to be
monophagous over their entire ranges. Of the species found

at Cape Arago, Adalaria sp., Ancula pacifica, Hallaxa chan,
Laila cockerelli, and Precuthona divae, so far as is known,
fit into this latter category (MCDONALD & NYBAKKEN,
1978; BEEMAN & WILLIAMS, 1980; GODDARD, 1981; pres-
ent study). Crimora coneja apparently feeds only on
Hincksina minuscula at Cape Arago, but it is doubtful that
this bryozoan occurs in San Diego County, California,
one of the other locations where C. coneja occurs (OSBURN,
1950). The generalist species at Cape Arago appear to
include Anisodoris nobilis, Dirona albolineata, Hermissenda
crassicornis, Rostanga pulchra, and Triopha catalinae
(ROBILLIARD, 1971a; NYBAKKEN & EASTMAN, 1977;
McDONALD & NYBAKKEN, 1978; BEEMAN & WILLIAMS,
1980; BLooM, 1981; JAECKLE, 1984; present study). I sus-
pect that most nudibranch species will be found to eat
relatively few prey species belonging to a few genera. Data
obtained in this study on the prey of Cape Arago nudi-
branchs are summarized in Table 2. These data are in-
complete. With the possible exceptions of Cadlina modesta,
Crimora coneja, and Hallaxa chani, more data are needed
on the prey of all Cape Arago nudibranchs.

Food data presented in Table 2 for Anisodoris nobilis,
Archidoris montereyensis, Archidoris odhnert, Diaulula san-
diegensis, and Discodoris heathi generally agree with data
presented by BLOoM (1981, table 2) on the order of sponges

Page 156

The Veliger, Vol. 27, No. 2

Table 2

Prey of Cape Arago opisthobranchs.

Nudibranch species
Adalaria sp.
Aeolidia papillosa
Ancula pacifica

Anisodoris nobilis

Archidoris monterey-
ensis

Archidoris odhneri
Cadlina luteomarginata
Cadlina modesta

Catriona columbiana
Crimora coneja
Cuthona abronia
Cuthona albocrusta
Dendronotus frondosus

Diaulula sandiegensis

Discodoris heathi
Doto amyra
Doto kya

Eubranchus rustyus
Flabellina trilineata
Hallaxa chani
Janolus fuscus
Laila cockerelli

Onchidoris muricata

Polycera atra
Precuthona divae

Rostanga pulchra

Triopha catalinae

Triopha maculata

Tritonia festiva

Prey

Hincksina minuscula*

Epiactis prolifera

among Barentsia sp.

Mycale macginitiet

Zygherpe hyaloderma

Lissodendoryx firma

Tedania gurjanovae*

Ophlitaspongia pennata (Lab)*

Halichondria panicea

Suberites sp.

unidentified orange encrusting
sponge

Hymeniacidon ungodon*

on Suberites sp.

Aplysilla glacialis*

Halisarca sp. (Lab)*

Aplysilla glacialis

Halisarca sp.*

Tubularia marina

Hincksina minuscula*

among small thecate hydroids

among small thecate hydroids

Obelia sp.

Haliclona sp. A

Sigmadocia sp.*

Mycale macginitiei*

Abietinaria sp.

among Plumularia sp. and
small thecate hydroids

Plumularia sp.

Tubularia marina

Halisarca sp.

arborescent bryozoans

Hincksina velata

Eurystomella bilabiata*
Microporella cribosa*

on Hincksina minuscula
arborescent bryozoans
Hydractinia sp.
Ophlitaspongia pennata
on Antho lithophoenix
on Hymedesmia sp. A
near Plocamia karykina
near Axocielita originalis

arborescent bryozoans

arborescent and encrusting
bryozoans

undescribed alcyonacean
octocoral*

Clavularia sp.

Gersemia rubiformis (Lab)

Table 2 (Continued)

Prey

Sacoglossan species
Aplysiopsis smithi
Placida dendritica

Cladophora sp.
Codium fragile

* New food record.
(Lab) opisthobranch species not found associated with this prey
in field, but ingestion of prey observed in laboratory.

most frequently eaten by these dorids in the San Juan
Archipelago and further support his general conclusion
that “‘caecate dorids prey on sponges with poorly-orga-
nized skeletons and acaecate dorids prey on sponges with
well-organized skeletons.”

The Cape Arago populations of a number of nudi-
branchs are clearly not food limited. For example, Ada-
laria sp., Crimora coneja, Laila cockerelli, and Onchidoris
muricata all feed on encrusting bryozoans that are abun-
dant at Cape Arago year-round (personal observation),
but the nudibranchs themselves are either rare or only
sporadically common. It is not known what factors are
preventing these species from becoming more abundant.
On the other hand, populations of Cadlina modesta and
Hallaxa chani (and Flabellina trilineata during periods of
high abundance) appear to be much closer to being limited
by the abundance of their food. Aplysilla glacialis and Hal-
isarca sp. are quite scarce; the abundance of Tubularia
marina fluctuates markedly, possibly as a result of eolid
predation.

Large numbers of 77opha catalinae, Janolus fuscus, and
Dirona albolineata are found together in the North Cove
inner boulder field during late summer and early fall.
Triopha catalinae and J. fuscus feed on arborescent bryo-
zoans (NYBAKKEN & EASTMAN, 1977; MCDONALD &
NYBAKKEN, 1978; personal observation), and D. albolinea-
ta eats a wide variety of prey including bryozoans (ROBIL-
LIARD, 1971a). It seems likely that some competition for
food occurs between these species during periods of co-
occurrence.

When Janolus fuscus are crowded in the laboratory they
often bite each other, sometimes tearing off and ingesting
cerata (Katheryn Young, personal communication; per-
sonal observation). I have also observed T7ztonia /estiva
taking bites out of each other in the laboratory. In one
instance I placed two newly collected specimens of 77-
tonia festiva (20 mm and 35 mm long, collected in June)
together in 500 mL of water. Within one day the larger
had eaten the smaller specimen. The occurrence of this
aggressive behavior and cannibalism has not been docu-
mented for either species in the field. It is interesting to
note, however, that aggressive behavior between 77ztonia
festiva could be adaptive in reducing feeding interference.
As mentioned previously, the alcyonacean prey of Cape

J. H. R. Goddard, 1984

Arago T7itonia festiva often occurs in large aggregations
of closely and evenly spaced colonies. A feeding attack by
Tritonia festiva on a colony results in contraction of the
remaining polyps of that colony for about two days (per-
sonal observation). 77ztonza festiva will not attack contract-
ed colonies. Feeding interference between 77itonia festiva
could thus be considerable at high slug densities (7.e., most
of the colonies would be contracted). Aggressive behavior
between 77itonia festiva might be a mechanism for reduc-
ing slug density and thus feeding interference.

In Hermissenda crassicornis, biting of conspecifics usu-
ally follows “‘sidling” behavior (ZACK, 1975; RUTOWSKI,
1982). Recent work has shown that sidling behavior is
actually ‘“‘alignment for copulation” (LONGLEY &
LONGLEY, 1982; RUTOWSKI, 1983). If not simply an at-
tempt to obtain food, the function of the biting that im-
mediately follows mating is obscure. It is possible that
biting of conspecifics is also closely related to mating in
Janolus fuscus and Tritonia festiva. Further studies of can-
nibalism and intraspecific aggression in these species and
their relationship to slug density, food density, and size
and reproductive state of the slugs are needed.

Triopha catalinae individuals are rarely found in close
proximity to one another (NYBAKKEN & EASTMAN, 1977:
282; personal observation), suggesting that aggressive in-
teractions may also occur between individuals of this
species. The feeding method of 7. catalinae (in which whole
branches of arborescent bryozoans are ripped off and in-
gested), and the laboratory observation of a large 7. cat-
alinae attacking and taking a sizable bite out of a Laila
cockerelli (personal observation) indicate that 7. catalinae
is physically capable of such aggression. Furthermore, one
wonders whether interspecific aggression or predation may
occur between 7. catalinae, Janolus fuscus, and Dirona al-
bolineata.

Ranges

The range extensions reported above for Cuthona flavo-
vulta, C. fulgens, and Polycera atra, and the occurrence
in spring and summer 1983 of the form of Ancula pacifica
common in California may be related to events associated
with the strong El Nino of 1982-1983 (PHILANDER, 1983).
These events included above-normal ocean temperatures
off the coast of North America (K. T. Briggs, Univ. of
California, Santa Cruz, personal communication; A.
McGee, Oregon Dept. Fish and Wildlife, personal com-
munication) and probably a weakening and partial rever-
sal of the usually south-moving California current
(CHELTON, 1981), as well as an intensification of the near-
shore, north-moving Davidson current that occurs in late
fall and early winter (BOLIN & ABBOTT, 1963;
SCHWARTZLOSE & REID, 1972). If the above species were
transported north (as veligers) with these anomalous events,
their occurrence at Cape Arago may be brief. On the other
hand, they may occur relatively consistently, but in low
numbers, at Cape Arago and were previously over-

Page 157

looked—this appears to be the case for Crimora coneja,
Cuthona cocoachroma, and Diaphana californica, all of which
were found at Cape Arago before the onset of the above
anomalous conditions.

I would like to recommend that dates of observation
always be given with range extensions and reports of un-
usual occurrence. For with increasing monitoring and un-
derstanding of coastal hydrographic conditions, it may be-
come possible to explain better the occurrence of many
species at the edges of their ranges, or to explain why a
species appears in an area for a time and then disappears
for long periods. For example, is it possible that the spec-
imens of Hopkinsia rosacea reported from Oregon by
STEINBERG (1963b) (see below) were carried north (as
veligers) from California with the warm waters and cur-
rents associated with the intense El Nino of the late 1950’s?
Mention of the date of observation would have helped
evaluate such a possibility. It is interesting that Ewrysto-
mella bilabiata, the only known prey of H. rosacea, is abun-
dant at Cape Arago year-round, but H. rosacea is usually
absent (personal observation).

The known range of Crimora coneja is puzzling. De-
spite extensive field observation of nudibranchs in central
California, only one specimen has been reported between
San Diego and Cape Arago (MCDONALD, 1983).

Some Thoughts on the Effects of Nudibranch
Predation on the Encrusting Animal
Community at Cape Arago

Low-light habitats at Cape Arago (crevices, caves, and
the undersurfaces of boulders and ledges) support a di-
verse encrusting community composed primarily of
sponges, bryozoans, colonial tunicates, and cnidarians. The
amount of free space varies depending, in part, on the
habitat and degree of physical disturbance. For example,
the undersurfaces of low intertidal ledges and stable boul-
ders exposed to little sedimentation tend to have little free
space, whereas the undersurfaces of boulders exposed to
seasonal sedimentation and overturning by waves tend to
possess large amounts of free space (personal observation).

As in any community, part of the encrusting animal
diversity at Cape Arago can be explained by the spatial
complexity of the habitats, coupled with niche diversifi-
cation and the evolution of habitat selection. However, the
coexistence of large numbers of species on relatively uni-
form surfaces suggests that other factors must be involved
in regulating species diversity. Factors that have been im-
plicated in affecting the diversity of other communities
and that are probably important at Cape Arago include:
predation and disease, fluctuations’in the physical and
biotic environments, physical disturbance in the forms of
sedimentation, boulder-overturning by surf, and erosion
(boring clams play a major role in erosion and production
of spatial complexity at Cape Arago), and the existence
of competitive networks among the encrusting species
(CONNELL, 1972, 1978; DayTon, 1971; Huston, 1979;

Page 158

HUTCHINSON, 1961; JACKSON & Buss, 1975; PAINE, 1974;
Sousa, 1979). The first three factors can maintain rela-
tively high levels of diversity by preventing competitive
equilibrium (at which time competitively inferior species
are excluded from the community) from being reached.
Of course, at high enough levels, these same factors can
keep diversity low. The existence of complex competitive
networks can increase the time necessary for competitive
exclusion to occur or it could mean that major competitive
dominants simply do not exist in the community (JACKSON
& Buss, 1975; JACKSON, 1979; KARLSON & JACKSON,
1981). As CONNELL (1978) and HusTON (1979) have dis-
cussed, a number of these factors probably operate si-
multaneously in any particular community, with the rel-
ative importance of each factor varying in different
communities. The observed diversity in a community is,
thus, the result of a “dynamic equilibrium” between the
growth rates of the component populations and the rates
of the above mentioned factors (HUSTON, 1979).

Nudibranchs, which are known to be important pred-
ators in some encrusting communities (BLOOM, 1981;
CLARK, 1975; DAYTON et al., 1974; RYLAND, 1970;
THOMPSON, 1964; and, on the basis of abundance,
NYBAKKEN, 1974, 1978), appear to be among the most
abundant and important predators of encrusting organ-
isms at Cape Arago (personal observation). Other signif-
icant predators of these organisms at Cape Arago include
prosobranchs such as Diodora aspera (Rathke, 1833) and
members of the family Lamellariidae, and probably var-
ious chitons, asteroids, and fish (MorRISs et al., 1980; per-
sonal observation). Certain flatworms, polychaetes, crus-
taceans, and pycnogonids are known to eat encrusting
animals (Morris et al., 1980) and may also be important,
especially with regard to predation on newly settled or-
ganisms.

Not knowing which encrusting species are competitive-
ly dominant at Cape Arago, I cannot say to what extent
nudibranchs prey on such species. But, because nudi-
branchs can eat large amounts of sessile organisms (see
data on Anisodoris nobilis, Cadlina luteomarginata, C. mo-
desta, Crimora coneja, Discodoris heathi, and Hallaxa chant)
and eat such a wide variety of prey, many of which are
among the more abundant species (personal observation),
they undoubtedly significantly affect the competitive re-
lationships in the encrusting community at Cape Arago.
Some examples of their effects follow.

Other than reducing the abundance of their prey, the
most obvious result of nudibranch predation on encrusting
communities is the creation of free space available for
larval recruitment or intrusion by surrounding organisms.
By consuming entire individuals or colonies, nudibranchs
can also alter the species composition under a boulder or
ledge.

Overgrowth is one of the primary mechanisms of com-
petition between encrusting organisms (JACKSON, 1979).
In some cases nudibranchs (and other predators) can erase
overgrowth events between encrusting species by preying

The Veliger, Vol. 27, No. 2

on the overgrowing species. This applies to sessile organ-
isms that can be completely grazed off the overgrown
species (7.e., certain sponges, tunicates, and perhaps fleshy
bryozoans). The sponge Halisarca sp. frequently over-
grows the bryozoan Eurystomella bilabiata at Cape Arago.
I have also seen it overgrowing the alcyonacean octocoral
prey of 77ritonia festiva. Twice I have collected Eurysto-
mella bilabiata overgrown by Halisarca sp. in order to feed
the sponge to laboratory Hallaxa chani. The dorids grazed
the sponge cleanly off the bryozoan, and within a day or
two the bryozoan lophophores were extended and feeding.
Of course, the viability of the overgrown organism will
depend on how long and how extensively it has been over-
grown and on its sensitivity to any allelopathic substances
made by the overgrowing organism. The large individual
of Aplysilla glacialis I observed eaten by Cadlina luteomar-
ginata and C. modesta (see notes on C. luteomarginata) had
partially overgrown some Cliona celata Grant, 1826. The
Cliona celata appeared healthy after the Aplysilla had been
grazed away. This is not too surprising, however, consid-
ering the shell-boring abilities of Cliona; it also suggests
that Aplysilla glacialis has little or no allelopathic effect on
Cliona celata.

Partial predation, which results in decreased feeding
and reproductive abilities of the grazed organism and can
also expose it to settlement by possibly superior competi-
tors (JACKSON & PALUMBI, 1979), is probably wide-
spread. It is inevitable in spatially complex microhabitats
where predators cannot reach all of their prey. Moreover,
how many predators, given the chance, actually graze all
of a sponge or every bryozoan zooid? Some predators are
simply not capable of consuming entire colonies (e.g., T7i-
tonia festiva feeding on alcyonacean octocorals, and many
hydroid-eating eolids that consume the hydranths, but not
the stalks and stolons from which hydranths can regen-
erate). An important question is, how much can a sessile
organism lose to predation and still survive with its re-
generative abilities?

The feeding of 77ritonia festiva on alcyonacean octocorals
is a vivid example of partial predation. I have observed
octocoral colonies being overgrown by Halisarca sp., co-
lonial tunicates, and the “social” tunicate Metandrocarpa
taylor. Huntsman, 1912. It would be interesting to com-
pare overgrowth of the octocoral in the presence and ab-
sence of 77itonia festiva.

The small, abundant dorid Rostanga pulchra feeds on
the upper layers of orange sponges (personal observation)
and appears to be more parasitic than predatory (though
more data are needed on its movements, feeding rates, and
sponge growth rates). By damaging the sponge, such su-
perficial grazing may increase the sponge’s susceptibility
to overgrowth or may speed overgrowth interactions al-
ready begun. On the other hand, such feeding could pos-
sibly facilitate release of allelopathic chemicals and thus
slow or prevent overgrowth.

The possible significance of the relationship between
nudibranchs and the encrusting community is suggested

J. H. R. Goddard, 1984

in a photograph I have of about 60 cm? of boulder un-
dersurface. The area is completely covered by the bryo-
zoans Eurystomella bilabiata and Hincksina velata and the
sponge Zygherpe hyaloderma. Two clumps of an uniden-
tified arborescent bryozoan are growing on the Hincksina.
Eurystomella and Hincksina are overgrowing each other in
different parts of the area, and the sponge is overgrowing
Hincksina, but the sponge is also being overgrown by Eu-
rystomella. Each of these organisms has at least one nu-
dibranch predator at Cape Arago.

The competitive relationships between encrusting or-
ganisms can be very complex. Overgrowth outcomes vary
between the same two species and often depend on en-
counter angle (JACKSON, 1979). Overgrowth may not be
complete and certainly does not always result in mortality.
Moreover, growth, regeneration, and recruitment rates of
the encrusting species all can affect the observed diversity
(KARLSON & JACKSON, 1981). If one adds predation (com-
plete and partial) by organisms such as nudibranchs to
this already complex system, as well as the other factors
affecting diversity previously mentioned, one is left with
an extraordinarily complex community for which com-
petitive equilibrium seems unlikely. Rather, there is prob-
ably a “dynamic equilibrium,” changing on both long and
short time scales, between the rates of competitive dis-
placement and the rates at which the other factors act to
prevent competitive exclusion (HusTon, 1979). The ob-
served diversity of intertidal encrusting organisms at Cape
Arago results from this dynamic equilibrium and is un-
doubtedly higher than would exist under a state of com-
petitive equilibrium.

Benthic Opisthobranchs Known from Oregon

The 66 benthic opisthobranch species presently known
from Oregon are listed in Table 3. Forty-seven of these
have been found at Cape Arago. Twenty-six are new rec-
ords for Oregon, and 28 are new to Cape Arago. The
ranges of Adalaria sp. and Anisodoris lentiginosa are ex-
tended southward, and those of Crimora coneja, Cuthona
cocoachroma, C. flavovulta, C. fulgens, Diaphana californica,
and Polycera atra northward. Depending on the status of
the questionable species listed in Table 3 (see below), the
Oregon total could rise to 71 and the Cape Arago total to
49.

Both SPHON (1972) and BELCIK (1975) reported finding
a Pleurobranchus sp. (Sphon from Strawberry Hill, and
Belcik from Cape Arago). These specimens could be dif-
ferent from each other and Berthella californica, or one (or
both) could be B. californica.

The Trinchesia sp. (which I have listed as Cuthona sp.)
reported by BELCIK (1975) on Yubularia sp. in the
Charleston boat basin could well be Catriona columbiana.
In my experience in the area, only Catriona columbiana,
Flabellina trilineata, and Hermissenda crassicornis occur on
Tubularia marina (and Cumanotus beaumonti on Tubularia
crocea—see below).

Page 159

Until the Eubranchus sp. collected by SPHON (1972) can
be re-examined, it is impossible to ascertain whether it is
an already described Eubranchus species (including one of
the two in Table 3) or belongs to an undescribed species.

SOWELL’s (1949) report of Cadlina pacifica from Cape
Arago is questionable. To my knowledge no other speci-
mens of this dorid have been found since BERGH’s (1879)
description of three specimens collected by Dall in Alaska.
Sowell reported finding at least five specimens and does
not describe any aspect of them except (p. 22) that they
were “always white about the same as the ground color
of Cadlina marginata.” My guess is that these were spec-
imens of Archidoris odhneri, a white dorid that was un-
described at the time.

BELCIK (1965) found Tritonia festiva and T. diomedea
(=T. exsulans), the two species of 77ritonia presently known
from the Pacific Northwest. It thus seems likely that the
“whitish” Jritonia sp. he reported dredged off Cape Ar-
ago (BELCIK, 1965, 1975) is an undescribed species, pos-
sibly that pictured by BEHRENS (1980:103). For this rea-
son I have not listed 7ritonza sp. under the ‘“‘questionable
species” in Table 3.

BELCIk’s (1965) Master’s Thesis on the parasitic co-
pepod /smaila monstrosa Bergh contains an appendix list-
ing 32 species of Oregon opisthobranchs that he had ex-
amined for parasites. Fifteen of these species were not
found by SPHON (1972) and became the basis of BELCIK’s
1975 paper. However, BELCIK (1975) includes an addi-
tional two species (77inchesia sp., which I have listed as
Cuthona sp., and Archidoris odhneri) that were not men-
tioned in his Master’s Thesis. In addition, the appendix
to his Thesis contains one species (Fiona pinnata) that
Sphon did not find but that Belcik, for some reason, did
not include in his 1975 paper. An ‘“‘Eolis sp.” is also men-
tioned in the Thesis and not in the 1975 paper. Presum-
ably this is the same as the 77inchesia sp. mentioned above,
and thus I have not included it in Table 3. I have included
BELCIK (1965) as a reference in Table 3 in order to pre-
sent the 17 additional species he found but did not include
in this 1975 paper. Both BEHRENS (1980) and Mc-
DONALD & NYBAKKEN (1980) list Dillon Beach, Marin
County, California as the northern limit of Dirona picta.
However, BELCIK (1975) found it on the docks of the
Charleston boat basin. I saw one specimen of D. picta
collected by the summer 1983 O.1.M.B. invertebrate zo-
ology class. The exact collection location is unknown.

SOWELL (1949) reported finding a form of Hermissenda
crassicornis at North Cove “among Laminaria and Costaria
and in association with Tropha carpentert and Dirona al-
bolineata.” He further states “this form appears to be spe-
cifically distinct from H. crassicornis, but has not been
definitely determined.” This form is undoubtedly /Janolus
fuscus, which occurs in large numbers in the same habitat
as Triopha catalinae and Dirona albolineata. BELCIK (1975)
wrote that Sowell “confused this form with Coryphella sp.
or Antiopella spp.”

STEINBERG (1963b) recorded Coos Bay, Oregon, as the

Page 160 The Veliger; Vol; 27, Now

Table 3

Benthic opisthobranchs known from Oregon.

Species Reference* Occurs at Cape Arago

Acanthodoris hudsoni MacFarland, 1905
Acanthodoris nanaimoensis O’ Donoghue, 1921 2.5,
Adalaria sp.

Aeolidia papillosa (Linnaeus, 1761)
Alderia modesta (Loven, 1844)

Aldisa sanguinea (Cooper, 1863)

Aldisa cooperi Robilliard & Baba, 1972
Ancula pacifica MacFarland, 1905
Anisodoris lentiginosa Millen, 1982
Anisodoris nobilis (MacFarland, 1905)
Aplysiopsis smithi (Marcus, 1961)
Archidoris montereyensis (Cooper, 1863)
Archidoris odhneri (MacFarland, 1966)
Armina californica (Cooper, 1863)
Bathydoris sp.

Berthella californica (Dall, 1900)

Cadlina flavomaculata MacFarland, 1905
Cadlina luteomarginata MacFarland, 1966 1, 4,
Cadlina modesta MacFarland, 1966

Catriona columbiana (O’Donoghue, 1922)

Crimora coneja Marcus, 1961

Cumanotus beaumont (Eliot, 1906)

Cuthona abronia (MacFarland, 1966)

Cuthona albocrusta (MacFarland, 1966)

Cuthona cocoachroma Williams & Gosliner, 1979

Cuthona flavovulta (MacFarland, 1966)

Cuthona fulgens (MacFarland, 1966)

Dendronotus frondosus (Ascanius, 1774) 2s 5),
Dendronotus subramosus MacFarland, 1966
Diaphana californica Dall, 1919

Diaulula sandiegensis (Cooper, 1863) MP
Dirona albolineata Cockerell & Eliot, 1905 N52
Dirona picta MacFarland in Cockerell & Eliot, 1905 4,
Discodoris heathi MacFarland, 1905 1,4
Doto amyra Marcus, 1961

Doto columbiana O’ Donoghue, 1921

Doto kya Marcus, 1961

Elysia hedgpethi (Marcus, 1961)

Eubranchus olivaceus (O’ Donoghue, 1922)

Eubranchus rustyus (Marcus, 1961)

Fiona pinnata (Eschscholtz, 1831)

Flabellina fusca O’ Donoghue, 1921

Flabellina trilineata (O’Donoghue, 1921) De
Hallaxa chani Gosliner & Williams, 1975
Hermaea vancouverensis O’Donoghue, 1924
Hermissenda crassicornis (Eschscholtz, 1831)
Hopkinsia rosacea MacFarland, 1905

Janolus fuscus O’ Donoghue, 1924

Laila cockerelli MacFarland, 1905
Melanochlamys (Aglaja) diomedea (Bergh, 1894)
Melibe leonina (Gould, 1852)

Onchidoris bilamellata (Linnaeus, 1767)
Onchidoris muricata (Miiller, 1776)

Onchidoris sp. (O. hystricina)

Phyllaplysia taylori Dall, 1900

Placida dendritica (Alder & Hancock, 1843)
Polycera atra MacFarland, 1905

Polycera zosterae O’ Donoghue, 1924

Precuthona divae Marcus, 1961

Rostanga pulchra MacFarland, 1905

aN
aD
~*~

62S
Fano)

rv

ORO

NRHA

ed

on
x

N

00 CO C&O CO CO UW CO OC CO} W UI CO} CO N © OC CO CO NH © OC CO CO CO} WM OC OC CO CO CO CO C OC OC CO OC CH CO CH OH C CO CO — CO WWM CO CO OC CO OC OC CO OC CO O&O CO OO lV
~ Km mM

NN

Ce ad

-
~ mK OM

on
“x

N
we &
x em mK

=

PN

NA
*

Wun

=
c=
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Ww

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J. H. R. Goddard, 1984

Page 161

Table 3 (Continued)

Species

Tochuina tetraquetra (Pallas, 1788)
Triopha catalinae (Cooper, 1863)
Triopha maculata MacFarland, 1905
Tritonia diomedea Bergh, 1894
Tritonia festiva (Stearns, 1873)
Tritonia sp.

Questionable species
Cadlina pacifica Bergh, 1879
Cuthona (Trinchesia) sp.
Eubranchus sp.
Pleurobranchus sp.
Pleurobranchus sp.

Reference* Occurs at Cape Arago
4,5
5 Ay as) x
8 x
355) x
2505568 x
4,5
1 x
4
2
2
4,5 x

* 1, SOWELL (1949); 2, SPHON (1972); 3, references cited by SPHON (1972); 4, BELCIK (1975); 5, BELCIK (1965); 6, STEINBERG

(1963a); 7, STEINBERG (1963b); 8, present study.

northern limit of Hopkinsia rosacea. This is the only record
of H. rosacea north of Abalone Beach, Humboldt County,
California (where a single specimen was found—see
JAECKLE, 1984). Specimens of H. rosacea from Coos Bay
were apparently collected by Lawrence Andrews, whom
STEINBERG (1963a) cited as her source of opisthobranch
specimens from Coos Bay. The only other species STE-
INBERG (1963a, b) reported from Coos Bay was Acantho-
doris nanaimoensis.

BELCIK (1975) reported Alderia modesta as uncommon
on Vaucheria mats on mudflats in Coos Bay. At least dur-
ing the summer, A. modesta can be found in abundance
feeding on mats of Vaucheria sp. in the South Slough of
Coos Bay (personal observation).

Five additional species that I have observed in the Coos
Bay area, but not at Cape Arago, are Cumanotus beau-
monti, Elysia hedgpethi, Fiona pinnata, Onchidoris bilamel-
lata, and Polycera zosterae. Cumanotus beaumonti occurs on
Tubularia crocea (Agassiz, 1862) in the Charleston boat
basin; a single specimen of E. hedgpethi was collected in
Coos Bay by the summer 1983 O.I.M.B. invertebrate zo-
ology class; F. pinnata occurs offshore on floating objects
covered with its prey, the gooseneck barnacle Lepas sp.;
O. bilamellata is found among Balanus glandula Darwin,
1854, on the pilings and breakwater of the Charleston
boat basin; and a single P. zosterae was collected from a
piling in the Charleston boat basin.

ACKNOWLEDGMENTS

I would like to thank Dr. Terry Gosliner of the California
Academy of Sciences for identifying specimens of Cuthona
cocoachroma, Sandra Millen of the University of British
Columbia for identifying specimens of Anisodoris lentigi-
nosa, Adalaria sp., and Onchidoris muricata, Drs. John and
Dorothy Soule of the Allan Hancock Foundation, Uni-
versity of Southern California and Patricia Cook of the
British Museum (Natural History) for examining and
identifying specimens of Hincksina minuscula, and Dr.

Cadet Hand, Director, Bodega Marine Laboratory, and
Dr. Frederick Bayer, Curator, Department of Inverte-
brate Zoology, Smithsonian Institution, for examining
specimens of the undescribed octocoral prey of Tritonia
festiva. 1 am indebted to Dr. Paul Rudy, Director, Oregon
Institute of Marine Biology, and Jean Hanna, O.1.M.B.
Librarian, for use of the O.I.M.B. facilities and for their
support and encouragement. Tom Wayne and Katheryn
Young provided specimens and much provocative discus-
sion. Elizabeth Hill’s sharp eye and inquisitive mind aid-
ed greatly in the field and stimulated many interesting
and useful discussions. My thanks also to Dr. Stanton
Cook and two reviewers for The Veliger for their helpful
comments on the manuscript.

Most of all I would like to thank Dr. Peter W. Frank,
my major professor, for his support, advice, review of the
manuscript, and the many stimulating discussions. He was
always willing to listen, gave freely of his ideas, and al-
lowed me to pursue my own interests.

This work was completed in partial fulfillment of the
requirements for a Master of Science degree in biology
from the University of Oregon, Eugene, Oregon.

LITERATURE CITED

BEEMAN, R. D. & G. C. WILLIAMS. 1980. Opisthobranchia
and Pulmonata: the sea slugs and allies. Pp. 308-354. In:
R. H. Morris, D. P. Abbott & E. C. Haderlie (eds.), In-
tertidal invertebrates of California. Stanford Univ. Press:
Stanford, Calif.

BEHRENS, D. W. 1980. Pacific coast nudibranchs. Sea Chal-
lengers: Los Osos, Calif. 112 pp.

BELcIK, F. P. 1965. The morphology of Jsmaila monstrosa Bergh
(Copepoda). Master’s Thesis, Oregon State Univ. 36 pp.

Be.cik, F. P. 1975. Additional opisthobranch molluscs from
Oregon. Veliger 17:276-277.

BERGH, R. 1878. Malacologische Untersuchungen, Band 2.
In: CG. Semper, Reisen in Archipel der Philippinen. Zweiter
Teil: Wissenschaftliche Resultate, Heft 14:603-645.

BERGH, R. 1879. On the nudibranchiate gastropod Mollusca

Page 162

The Veliger; Volh27/-iiowZ

of the North Pacific Ocean, with special reference to those
of Alaska. Part 1. Proc. Acad. Natur. Sci. Phila. 31:71-132.

BeRGH, R. 1880. On the nudibranchiate gastropod Mollusca
of the North Pacific Ocean, with special reference to those
of Alaska. Part 2. Proc. Acad. Natur. Sci. Phila. 32:40-127.

BERGQUIST, P. R. 1978. Sponges. Univ. Calif. Press: Berkeley,
Los Angeles. 268 pp.

BertscH, H. 1969. Cadlina modesta: a range extension, with
notes on habitat and a color variation. Veliger 12:231-232.

Bertscu, H. & S. JOHNSON. 1982. Three new species of dorid
nudibranchs (Gastropoda: Opisthobranchia) from the
Hawaiian Islands. Veliger 24:208-218.

Bioom, S. A. 1981. Specialization and noncompetitive re-
source partitioning among sponge-eating dorid nudibranchs.
Oecologia 49:305-315.

Bouin, R. L. & D. P. ABpotr. 1963. Studies on the marine
climate and phytoplankton of the central coastal area of
California, 1954-1960. Calif. Coop. Oceanic Fish. Invest.
Rep. 9:23-45.

Bonar, D. B. 1978. Morphogenesis at metamorphosis in opis-
thobranch molluscs. Pp. 177-196. In: F. Chia & M. E. Rice
(eds.), Settlement and metamorphosis of marine invertebrate
larvae. Elsevier/North-Holland Biomedical Press: New
York.

CHELTON, D. B. 1981. Interannual variability of the Califor-
nia current—physical factors. Calif. Coop. Oceanic Fish.
Invest. Rep. 22:34-48.

Cxiark, K. B. 1975. Nudibranch life cycles in the northwest
Atlantic and their relationship to the ecology of fouling com-
munities. Helgolander Wiss. Meeresunters. 27:28-69.

CONNELL, J. H. 1972. Community interactions on marine rocky
intertidal shores. Ann. Rev. Ecol. Syst. 3:169-192.

CONNELL, J. H. 1978. Diversity in tropical rain forests and
coral reefs. Science 199:1302-1310.

CosTELLo, D. P. 1938. Notes on the breeding habits of the
nudibranchs of Monterey Bay and vicinity. J. Morphol. 63:
319-343.

Dayton, P. K. 1971. Competition, disturbance, and commu-
nity organization: the provision and subsequent utilization
of space in a rocky intertidal community. Ecol. Monogr. 41:
351-389.

Dayton, P. K., G. A. ROBILLIARD, R. T. PAINE & L. B. DayTON.
1974. Biological accommodation in the benthic community
at McMurdo Sound, Antarctica. Ecol. Monogr. 44:105-
128.

DEHNEL, P. A. & D. C. Konc. 1979. The effect of tempera-
ture on developmental rate in the nudibranch Cadlina luteo-
marginata. Can. J. Zool. 57:1835-1844.

EysTer, L. S. 1981. Observations on the growth, reproduction
and feeding of the nudibranch Armina tigrina. J. Moll. Stud.
47:171-181.

EysTer, L. S. & S. E. STANCYK. 1981. Reproduction, growth,
and trophic interactions of Doriopsilla pharpa Marcus in
South Carolina. Bull. Mar. Sci. 31:72-82.

GopparD, J. H. R. 1981. Range extension and notes on the
food, morphology, and color pattern of the dorid nudibranch
Hallaxa chan. Veliger 24:155-158.

GosLINER, T. M. 1982. The genus /anolus (Nudibranchia:
Arminacea) from the Pacific Coast of North America, with
reinstatement of /anolus fuscus O’ Donoghue, 1924. Veliger
24:219-226.

GosLINER, T. M. & G. C. WILLIAMS. 1970. The opistho-

branch mollusks of Marin County, California. Veliger 13: .

175-180.
GREENE, R. W. 1968. The egg masses and veligers of southern
California sacoglossan opisthobranchs. Veliger 11:100-104.
GREENE, R. W. 1970. Symbiosis in sacoglossan opistho-

branchs: symbiosis with algal chloroplasts. Malacologia 10:
357-368.

Hurst, A. 1967. The egg masses and veligers of thirty north-
east Pacific opisthobranchs. Veliger 9:255-288.

Huston, M. 1979. A general hypothesis of species diversity.
Amer. Natur. 113:81-101.

HUTCHINSON, G. E. 1961. The paradox of the plankton. Amer.
Natur. 95:137-145.

Jackson, J. B.C. 1979. Overgrowth competition between en-
crusting cheilostome ectoprocts in a Jamaican cryptic reef
environment. J. Anim. Ecol. 48:805-823.

Jackson, J. B.C. & L. W. Buss. 1975. Allelopathy and spa-
tial competition among coral reef invertebrates. Proc. Natl.
Acad. Sci. U.S.A. 72:5160-5163.

Jackson, J. B.C. & S. R. PALUMBI. 1979. Regeneration and
partial predation in cryptic coral reef environments: prelim-
inary experiments on sponges and ectoprocts. Pp. 303-308.
In: C. Levi & N. Boury-Esnault (eds.), Biologie des spon-
giaires. Centre National de la Recherche Scientifique: Paris.

JAECKLE, W. B. 1981. Range extensions of several opistho-
branchs from Humboldt County, California. Opisthobranch
Newsletter 13:23-24.

JAECKLE, W. B. 1984. The opisthobranch molluscs of Hum-
boldt County, California. Veliger 26:207-213.

Karson, R. H. & J. B. C. Jackson. 1981. Competitive net-
works and community structure: a simulation study. Ecol-
ogy 62:670-678.

LAMBERT, P. 1976. Records and range extensions of some
northeastern Pacific opisthobranchs (Mollusca: Gastro-
poda). Can. J. Zool. 54:293-300.

LONGLEY, R. D. & A. J. LONGLEY. 1982. Hermissenda: ago-
nistic behavior or mating behavior? Veliger 24:230-231.

MacFarLanD, F. M. 1966. Studies of opisthobranchiate mol-
lusks of the Pacific Coast of North America. Mem. Calif.
Acad. Sci. 6:1-546.

Marcus, E. 1961. Opisthobranch mollusks from California.
Veliger 3 (Suppl.):1-85.

McDona.p, G. R. 1983. A review of the nudibranchs of the
California coast. Malacologia 24:114-276.

McDona.p, G. R. & J. W. NYBAKKEN. 1978. Additional
notes on the food of some California nudibranchs with a
summary of known food habits of California species. Veliger
21:110-119.

McDona.Lp, G. R. & J. W. NyBAKKEN. 1980. Guide to the
nudibranchs of California. American Malacologists, Inc.:
Melbourne, Florida. 72 pp.

MILLEN, S. V. 1982. A new species of dorid nudibranch (Opis-
thobranchia: Mollusca) belonging to the genus Anisodoris.
Can. J. Zool. 60:2694-2705.

MILLER, M. C. 1962. Annual cycles of some Manx nudi-
branchs, with a discussion of the problem of migration. J.
Anim. Ecol. 31:545-569.

Morris, R. H., D. P. ABBoTT & E. C. HADERLIE (EDS.). 1980.
Intertidal invertebrates of California. Stanford Univ. Press:
Stanford, Calif. 690 pp.

NYBAKKEN, J. 1974. A phenology of the smaller dendronota-
cean, arminacean, and aeolidacean nudibranchs at Asilomar
State Beach over a twenty-seven month period. Veliger 16:
370-373.

NYBAKKEN, J. 1978. Abundance, diversity, and temporal vari-
ability in a California nudibranch assemblage. Mar. Biol.
45:129-146.

NyYBAKKEN, J. & J. EASTMAN. 1977. Food preferences, food
availability and resource partitioning in 7ropha maculata
and Triopha carpenter: (Opisthobranchia: Nudibranchia).
Veliger 19:279-289.

O’ DONOGHUE, C. H. & E. O7DONOGHUE. 1922. Notes on the

J. H. R. Goddard, 1984

nudibranchiate Mollusca from the Vancouver Island region.
II. The spawn of certain species. Trans. Roy. Canad. Inst.
14:131-143.

OsBurRN, R. C. 1950. Bryozoa of the Pacific Coast of America.
Cheilostomata—Anasca. Allan Hancock Pacific Exped. 14:
1-269.

Paine, R. T. 1974. Intertidal community structure. Experi-
mental studies on the relationship between a dominant com-
petitor and its principal predator. Oecologia 15:93-120.

PERRON, F. E. & R. D. TURNER. 1977. Development, meta-
morphosis, and natural history of the nudibranch Doridella
obscura Verrill (Corambidae: Opisthobranchia). J. Exp. Mar.
Biol. Ecol. 27:171-185.

PHILANDER, S. G. H. 1983. El Nino southern oscillation phe-
nomena. Nature 302:295-301.

Potts, G. W. 1970. The ecology of Onchidoris fusca (Nudi-
branchia). J. Mar. Biol. Assoc. U.K. 50:269-292.

ROBILLIARD, G. A. 1971a. Predation by the nudibranch Dirona
albolineata on three species of prosobranchs. Pacific Sci. 25:
429-435.

ROBILLIARD, G. A. 1971b. Range extension of some northeast
Pacific nudibranchs (Mollusca: Gastropoda: Opisthobran-
chia) to Washington and British Columbia, with notes on
their biology. Veliger 14:162-165.

ROBILLIARD, G. A. & K. Basa. 1972. Aldisa sanguinea cooperi
subspec. nov. from the coast of the state of Washington, with
notes on its feeding and spawning habits (Nudibranchia:
Doridae: Aldisinae). Publ. Seto Mar. Biol. Lab. 19:409-
414.

Rutowskl, R. L. 1982. The temporal structure of behavioral
interactions in Hermissenda crassicornis (Opisthobranchia).
Veliger 24:227-229.

Rutowskl, R. L. 1983. Mating and egg mass production in
the aeolid nudibranch Hermissenda crassicornis (Gastropoda:
Opisthobranchia). Biol. Bull. 165:276-285.

RYLAND, J. S. 1970. Bryozoans. Hutchinson Univ. Library:
London. 175 pp.

SCHWARTZLOSE, R. A. & J. L. Remp. 1972. Near-shore cir-
culation in the California current. Calif. Coop. Oceanic Fish.
Invest. Rep. 16:57-65.

SMITH, R. I. & J. T. CARLTON (EDs.). 1975. Light’s manual.

Page 163

Intertidal invertebrates of the central California coast. 3rd
ed. Univ. Calif. Press: Berkeley, Calif. 716 pp.

Sousa, W. P. 1979. Disturbance in marine intertidal boulder
fields: the non-equilibrium maintenance of species diversity.
Ecology 60:1225-1235.

SOWELL, R. R. 1949. Taxonomy and ecology of the nudibran-
chiate Mollusca of the Coos Bay, Oregon region. Master’s
Thesis, Oregon State College. 54 pp.

SPHON, G. 1972. Some opisthobranchs (Mollusca: Gastropo-
da) from Oregon. Veliger 15:153-157.

STEINBERG, J. E. 1963a. Notes on the opisthobranchs of the
west coast of North America—III. Further nomenclatorial
changes in the order Nudibranchia. Veliger 6:63-67.

STEINBERG, J. E. 1963b. Notes on the opisthobranchs of the
west coast of North America—IV. A distributional list of
opisthobranchs from Point Conception to Vancouver Island.
Veliger 6:68-73.

SWENNEN, C. 1961. Data on distribution, reproduction, and
ecology of the nudibranchiate molluscs occurring in the
Netherlands. Neth. J. Sea Res. 1:191-240.

THompson, T. E. 1961. Observations on the life history of the
nudibranch Onchidoris muricata (Miller). Proc. Malacol.
Soc. Lond. 34:239-242.

THompson, T. E. 1964. Grazing and the life cycles of British
nudibranchs. Brit. Ecol. Soc. Symp. 4:275-297.

TuHompson, T. E. 1967. Direct development in the nudibranch
Cadlina laevis, with a discussion of developmental processes
in opisthobranchs. J. Mar. Biol. Assoc. U.K. 47:1-22.

TuHompson, T. E. 1976. Biology of opisthobranch molluscs.
Ray Soc.: London. Vol. 1. 207 pp.

Topp, C. D. 1978. Gonad development of Onchidoris muricata
(Miller) in relation to size, age and spawning (Gastropoda:
Opisthobranchia). J. Moll. Stud. 44:190-199.

Topp, C. D. 1979. The population ecology of Onchidoris bi-
lamellata (L.) (Gastropoda: Nudibranchia). J. Exp. Mar.
Biol. Ecol. 41:213-255.

WitLows, A. O. D. 1978. Physiology of feeding in 77itonia 1.
Behavior and mechanics. Mar. Behav. Physiol. 5:115-135.

Zack, S. 1975. A description and analysis of agonistic behavior
patterns in an opisthobranch mollusc, Hermissenda crassi-
cornis. Behaviour 53:238-267.

The Veliger 27(2):164-192 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

Comparison of Acteocina canaliculata (Say, 1826),

A. candei (dW Orbigny, 1841), and A. atrata spec. nov.

(Gastropoda: Cephalaspidea)

PAUL S. MIKKELSEN anp PAULA M. MIKKELSEN

Harbor Branch Foundation, Inc., R.R. 1, Box 196,
Ft. Pierce, Florida 33450

Abstract. The type species of the genus Acteocina, Acteon wetherilli Lea, 1833, is synonymized with
Volvaria canaliculata Say, 1826, type species of the genus Utriculastra; because Utriculastra and Cylichnel-
la are synonymous, Acteocina is the senior synonym. The systematics of A. canaliculata and A. atrata
spec. nov. are examined, and a neotype is designated for A. canaliculata. Descriptions are presented of
shell, radular, and gizzard plate morphologies; geographic and bathymetric distributions are re-evalu-
ated based on museum collections. Floridian specimens of A. canaliculata have planktotrophic devel-
opment, hatching in 4 days and settling in 24 days; A. atrata has capsular metamorphic development,
hatching in 9 days as benthic juveniles. A preliminary review of Acteocina candei (d’Orbigny, 1841) is
given, and a lectotype is designated. Acteocina candei distinctly differs conchologically from A. canali-
culata, is resurrected from synonymy, and is considered a valid species.

INTRODUCTION

Acteocina canaliculata (Say, 1826) and A. candei (d’Orbi-
gny, 1841) are small, cephalaspid gastropods common
throughout much of the western Atlantic. Intraspecific
variability of shell and radular characters has obscured
interspecific differences, making them consistently diffi-
cult to distinguish. Publications reporting either species
may actually have considered both species simultaneously
or confused the two.

Acteocina canaliculata and A. candei have been assigned
to many genera, most notably Utriculus Brown, 1844,
Tornatina A. Adams, 1850, Retusa Brown, 1827, and Ac-
teocina Gray, 1847. Acteocina has had the most frequent
usage in recent years. However, Marcus (1956:41),
Marcus (1977:2), and CERNOHORSKY (1978:83) advocat-
ed restriction of the genus Acteocina to fossil forms because
(1) the type species, A. wetherilli (Lea, 1833), was de-
scribed as a fossil whose internal anatomy will never be
known, and (2) knowledge of internal anatomy is neces-
sary to define cephalaspid genera according to modern
standards. hus, they concluded that fossil species of this
group cannot be reliably allocated to Recent genera. Fol-
lowing this reasoning, Marcus (1977) allocated A. cana-
liculata and A. cande: (which she synonymized with A.
canaliculata) to Utriculastra Thiele, 1925. RUDMAN (1978)

incorrectly placed A. canaliculata (and thus A. candez) in
the genus Tornatina, apparently unaware of MARcus’
(1977) work restricting Tornatina on the basis of radular
and gizzard plate morphologies, and because he incor-
rectly believed that the genus Cylichnella Gabb, 1873,
lacked jaws (see MARCUS, 1956:39; GOSLINER, 1979:88).
GOSLINER (1979) determined that Utriculastra was a ju-
nior synonym of Cylichnella based on similar arrange-
ments of the reproductive system. Therefore, according to
the more recent literature, A. canaliculata and A. candei
should be placed in the genus Cylichnella.

The familial placement of Acteocina (as Cylichnella, etc.)
has likewise been varied; it has most recently been placed
(Marcus, 1977; RUDMAN, 1978; GOSLINER, 1980) in the
Scaphandridae G. O. Sars, 1878. This family was consid-
ered (ABBOTT, 1974; CERNOHORSKY, 1978), apparently on
a conchological basis alone, to be a junior synonym of
Cylichnidae H. & A. Adams, 1854 (not of A. Adams,
1850, as stated by ABBOTT, 1974; not of Rudman, 1978).
Although RUDMAN (1978:105) incorrectly reproposed Cy-
lichnidae as a new family, he restricted the family to the
genus Cylichna on the basis of anatomy. Therefore, ac-
cording to Rudman, Cylichnidae and Scaphandridae are
both valid and distinct families. GOSLINER (1980) refuted
RUDMAN’s (1978) distinction between Cylichnidae and

P. S. Mikkelsen & P. M. Mikkelsen, 1984

Scaphandridae, considering them synonymous. However,
Gosliner chose Scaphandridae as the senior synonym, be-
cause he incorrectly considered Cylichnidae of Rudman,
1978, rather than of H. & A. Adams, 1854. Cylichnidae
H. & A. Adams, 1854, is the proper senior synonym and
would be the correct family for Acteocina following
GOSLINER’s (1980) synonymy. Following RUDMAN (1978),
Scaphandridae is correct. The family Acteocinidae Pils-
bry, 1921, may be valid as well (see CERNOHORSKY, 1978).

In 1962, WELLS & WELLS attempted to distinguish
“Retusa” canaliculata from Acteocina candei. The diag-
nostic characters used were: radular characters (shape and
number of denticles for lateral and rachidian teeth), pro-
toconch appearance (degree of protrusion and number of
whorls), shell shape (spire height, basal shape, convexity
of the whorls, and apertural shape), habitat, and type of
larval development. Wells & Wells found direct-devel-
oping larvae in field-collected egg masses of “R.” canali-
culata, and assumed planktonic development in A. candei
from the appearance of the protoconchs of the adults.
However, FRANZ (1971a, b) found planktotrophic devel-
opment in eggs deposited in the laboratory by adults of A.
canaliculata collected from Connecticut. Franz explained
this discrepancy by suggesting (1) that Wells & Wells,
using field-collected egg masses from North Carolina, had
unknowingly reared some other cephalaspid, (2) that poe-
cilogony (multiple patterns of development within a
species) exists for A. canaliculata, or (3) that cryptic species
were present. GOSLINER’s (1979) observations from the
estuarine Pictou Harbor, Nova Scotia, also determined
planktotrophic development for A. canaliculata.

Marcus (1977:14) examined additional specimens of
“Utriculastra” cande: and “U.” canaliculata and deter-
mined that their shell and radular characters were highly
variable and overlapping. Although Marcus noted differ-
ent morphologies in the gizzard plates of each species,
these differences were attributed to varying degrees of des-
iccation, and the plates were considered “‘identical.”’ Pos-
sibly due to WELLS & WELLS’ (1962) questionable devel-
opmental observations, Marcus (1977) failed to address
Wells & Wells’ criterion of developmental type as a dis-
tinguishing character between the two species. Based on
her observations, and on identical morphologies of the
male reproductive structures, Marcus synonymized “U.”
cande: with “U.” canaliculata. This synonymy had been
suggested many years earlier by DALL (1889:45).

Fifteen shells and 5 radulae of “Utriculastra”’ canalicu-
lata were figured by Marcus (1977), but no attempt was
made to document further the degree of variability. MIK-
KELSEN & MIKKELSEN (1982) closely examined the shell
and radular variability of “U.” canaliculata (as defined by
Marcus, 1977) and indicated that “U.” candei is an im-
mature form of “U.”’ canaliculata, thus supporting the syn-
onymy of Marcus. MIKKELSEN & MIKKELSEN (1983) not-
ed the presence of two types of larval development in the
“single species,” ““Cylichnella” canaliculata, and suggested
that “C.” candei be resurrected as valid.

Page 165

In the present study, embryonic, larval, and postlarval
morphological characters, and examination of museum
collections are utilized to:

(1) show that Wells & Wells’ “Retusa canaliculata” is
actually an undescribed species, living sympatrically with
Acteocina canaliculata in eastern Florida;

(2) determine the correct generic placement for A. ca-
naliculata and A. candei;

(3) examine in detail the postlarval intraspecific vari-
ation of the shell, radula, and gizzard plates of A. cana-
liculata and the new species;

(4) describe the larval development of A. canaliculata
as well as that of the new species; and

(5) partially characterize Acteocina candei, in contrast
with A. canaliculata and the new species.

MATERIALS ano METHODS
Collections

The principal study site was the 195 km-long Indian
River lagoon, along the central east coast of Florida (Fig-
ure 7D). Salinity generally ranged from 18 to 36 ppt,
although extremes of 8 and 42 ppt were recorded during
the study. Live snails were sieved, using 0.5 mm-mesh
screens, from bare or vegetated subtidal sand or mud sub-
strates. Dried or wet-preserved specimens from various
museums and private collections were utilized to redeter-
mine geographic and bathymetric distributions. Fossil type
specimens were examined for synonymies; however, be-
cause additional fossil material was not thoroughly stud-
ied, detailed paleontological distributions are not given.
Cited repositories and other sources are as follows:

ANSP—Academy of Natural Sciences of Philadelphia,
Philadelphia, PA

BM(NH)—British Museum (Natural History), London

CAS—California Academy of Sciences, San Francisco, CA

ChM—Charleston Museum, Charleston, SC

D. Franz Collection—Department of Biology, Brooklyn
College of the City University of New York, Brooklyn,
NY

HMNS—Houston Museum of Natural Science, Hous-
ton, TX

IRCZM—Indian River Coastal Zone Museum, Harbor
Branch Foundation, Ft. Pierce, FL

MACN—Museo Argentino de Ciencias Naturales, Bue-
nos Aires, Argentina

MCZ—Museum of Comparative Zoology, Harvard Uni-
versity, Cambridge, MA

MORG—Museo Oceanografico, Rio Grande, Brazil

PRI—Paleontological Research Institution, Ithaca, NY

ROM1Z—Royal Ontario Museum, Toronto, Ontario,
Canada

R. Van Dolah Collection—South Carolina Marine Re-
sources Research Institute, Charleston, SC

UNC-IMS-— Institute of Marine Sciences, University of
North Carolina, Morehead City, NC

Page 166

USNM—National Museum of Natural History, Wash-
ington, DC.

In synonymies, a dagger (f) preceding a species name
indicates fossil type specimens. In “Material examined”
sections, an “‘L” indicates that at least some of the speci-
mens in the lot were live-collected and contained soft parts;
an “E” indicates that all specimens were empty shells.

Either original figures or type specimens were exam-
ined of all western Atlantic Acteocina canaliculata-like
forms, fossil and Recent, described to date. Types were
examined if figures even remotely resembled the species
discussed herein. Two exceptions were Cylichna virginica
Conrad, 1868, and Tornatina cylindrica Emmons, 1858,
for which no types could be located to clarify the ambig-
uous original figures.

Postlarval Observations

Specimens with intact protoconchs, collected from var-
ious localities throughout the study area, were chosen for
statistical analyses. These encompassed a wide range of
shell lengths, but excluded specimens not retained by the
0.5 mm-mesh collecting sieve. Each shell was illustrated
using a stereomicroscope and camera lucida providing
permanent records of shell length, shell width, spire height
and angle (Figure 1A), and percent of protoconch protru-
sion (Figure 1D). Drawings were essential because par-
tial destruction of the shells was necessary to remove the
retracted animals.

Percent of protoconch protrusion was determined (Fig-
ures 1E-G) utilizing the circle, (x — h)? + (y — k)? =r’,
approximated by the periphery of the protoconch, where
(h, k) are the coordinates of the center, (x, y) are the
coordinates of any point on the circle, and r is the radius.
With the ordinate axis drawn through the center of the
circle, and the abscissa through the lateral suture points of
the protoconch with the first postnuclear whorl, the y-co-
ordinate (h) of the center equals zero, and the equation
reduces to Equation I: x? + (y — k)? =r’. Measurement
of the protoconch’s exposed height (b) and width at the
suture (2a) yields 3 points on the circle: (a, 0), (—a, 0),
and (0, b). For point (a, 0) or (~a, 0), y = 0, and Equa-
tion I becomes Equation II: a? + k? = r?. For point (0, b),
x = 0, and Equation I becomes Equation III: b? — k? =
r’ or Equation IV: b — k=r. Subtracting Equation II
from Equation III yields Equation V: k = (b? — a?)/2b.
Using a and b obtained from actual protoconch measure-
ments, Equation V can be solved for k, which is used in
Equation IV to determine the radius: r=b — (b — a)/
2b. The diameter of the circle (2r) and the exposed height
(b) are then used to determine the percentage (P) of pro-
toconch protrusion: P = b/2r x 100%.

Radulae and gizzard plates were extracted by dissolving
the surrounding soft tissue in a solution of 10% sodium
hydroxide at 20°C (LINDBERG, 1977). In addition to sug-
gestions by TURNER (1960) and SOLEM (1972), handling

The Veliger; Vol) 274 Nor

of small radulae was facilitated by use of a cat’s vibrissa
mounted on the tip of a probe. Gizzard plates were ob-
served and subsequently stored in 70% ethanol, or dried.
Radulae were simultaneously stained and permanently
mounted on glass slides, using Turtox CMC-9AF low-
viscosity stain-mountant tinted with acid fuchsin (Masters
Chemical Co., Inc., Des Plaines, IL). Due to the ex-
tremely small size of the radula, this one-step operation
eliminated the loss of many radulae. Each radula was
mounted so that at least some of the lateral teeth were
oriented as in Figure 1B. All slide-mounted radulae were
illustrated using a compound microscope and camera lu-
cida. These drawings provided the width, angle, and num-
ber of denticles for lateral teeth (Figure 1B), plus the
width and number of denticles for rachidian teeth (Figure
1C). Radulae used for scanning electron microscopy were
cleaned by sonication, following the method of SOLEM
(1972). Radulae and gizzard plates were air dried and
scanned using a Zeiss Novascan-30.

Shell terminology is after SMITH (1967a:758-760) and
KNIGHT (1952:7-9); radular terminology is after BERTSCH
(1977). Providing regressions of various characters follows
the initiative of BERTSCH (1976).

Larval Development

Adults were collected during each month of the year
from at least one of several locations (Figure 7D). Adults
from a single site were left together for about 24 h in a
finger bowl with seawater and sand substrate from the
collection site. Individuals were then isolated in compart-
mented plastic trays, each containing filtered seawater and
a thin layer of sand. Each compartment was checked daily,
for up to 14 days, and egg masses were removed to com-
partmented plastic trays containing seawater only. Adults
and developing egg masses were maintained at ambient
laboratory conditions of 22-25°C with variable lighting,
or under incubation at 22°C with a daily light cycle of 12
h light/12 h dark.

Planktotrophic larvae were reared using larval culture
sieves placed in 300-mL beakers. Each larval sieve con-
sisted of a 4.5-cm section of acrylic tubing, 7.6 cm in
diameter, closed at the base by a 33 wm-mesh nitex screen.
Larvae from a single egg mass were reared in the same
sieve. Survivorship was maximized by adding antibiotics
(5 mg/mL streptomycin sulfate plus 5 mg/mL penicillin-
G) to 0.5 um-filtered, 36-ppt seawater (SWITZER- DUNLAP
& HADFIELD, 1981:207). Cetyl alcohol flakes were floated
on the water to prevent larvae from being trapped by the
surface tension (HURST, 1967). Veligers were fed to excess
with Stephanoptera sp., a 10 um-diameter, unicellular green
alga. Water and food supply were changed every other
day.

Direct-developed hatchlings and metamorphosed
planktic larvae were transferred to 300-mL beakers of
filtered seawater. Amorphous organic material, collected

P. S. Mikkelsen & P. M. Mikkelsen, 1984

LENGTH

— WIDTH ——
ANGLE
eA

2

<i LENGTH

v/

€ ae

hema

Page 167

WIDTH
AT SUTURE

EXPOSED
| HEIGHT

Figure 1

Shell and radular parameters. A. Shell in apertural view. B. Lateral radular tooth. C. Rachidian radular tooth.
D. Apical view of protoconch. E, F, and G. Diagrammatic protoconchs of increasing degree of protrusion, showing

points and distances used in calculating percent protrusion.

from sedimentary detritus at the collection site or from a
laboratory running-seawater system, provided food for the
juveniles. After this material was suspended by swirling,
the larger particles were allowed to settle and the finer
suspended material was decanted off. It was this fine or-
ganic material which was added in small quantities to the

beakers containing the juveniles, to form a thin bottom
layer of food. Juveniles were visually located and trans-
ferred to new seawater and food once a week.

Larval shells were prepared for SEM either by pres-
ervation in 80% ethanol or by soaking in a dilute solution
of household bleach to remove the soft tissues. The latter

Page 168

method was considered least desirable because opercula
were invariably lost. The larval shells were then dried,
mounted, and scanned as described above for the radulae
and gizzard plates.

SYSTEMATIC RESULTS
Genus Acteocina Gray, 1847

Acteocina GRAY, 1847:160.
Cylichnella GABB, 1873:273-274.
Utriculastra THIELE, 1925:235.

The holotype of Acteon wetherill: Lea, 1833 (type species
of the genus Acteocina) is extremely worn, and lacks its
protoconch. The type locality of A. wetherilli is Deal, New
Jersey, from deposits of Miocene age (RICHARDS, 1968).
L. D. Campbell (personal communication, 1983) indicat-
ed that the type locality may be as young as Pleistocene.

In all discernible conchological characters, Acteocina
wetherilli agrees with the Recent species Volvaria canali-
culata Say, 1826, type species of the genus Utriculastra.
This synonymy was first suggested by OLSSON & Har-
BISON (1953) and reiterated by OLSSON & McGINTy
(1958), OLSSON (1964), and CAMPBELL et al. (1975). The
genus Acteocina is therefore applicable to Recent forms
(contrary to Marcus, 1956:41). The anatomical charac-
teristics of A. canaliculata may now be assumed to be ap-
plicable to the genus. In addition, the genus Utriculastra
becomes a junior synonym of Acteocina.

Utriculastra and Cylichnella are presently synonymous,
in accordance with the anatomical studies of GOSLINER
(1979). Although GOSLINER (1979) additionally included
Tornastra Marcus, 1977, in this synonymy, we prefer to
omit it here because of the distinctive gizzard plate and
radular anatomy of Bulla eximia Baird, 1863, the type
species of Tornastra (see MARcus, 1977). DALL (1908)
listed eight additional synonyms of Cylichnella, but they
are either incorrect or unconfirmed herein.

Our experience has determined that Acteocina-like
species can be distinguished conchologically. In the case
of Acteocina, we have conchologically matched its fossil
type specimen with a Recent species, and have subse-
quently defined the genus using the internal characteris-
tics of Recent specimens. This action does not differ from
the conchological matching of dead-collected Recent type
specimens (of prosobranch and other mollusks) with living
individuals, which are then used to redescribe the species,
complete with internal anatomy. Although this procedure
is followed frequently in malacology, it has been consid-
ered inappropriate for cephalaspids (Marcus, 1956;

The Veliger, Vol. 27, No. 2

Marcus, 1977). In our opinion, it must be considered
acceptable (for example, in the case of A. candez).

Until further studies at the species level are complete
for Acteocina and other closely related genera, resolution
of the familial placement of Acteocina is not possible.

Acteocina canaliculata (Say, 1826)
(Figures 2 to 5)

Volvaria canaliculata SAY, 1826:211.

[non Bulla canaliculata D’Orbigny, 1841:133-134; 1842:
pl. 4 bis, figs. 21-24.]

Bullina canaliculata: Say, 1832:pl. 39.

tActeon wetherilli LEA, 1833:213, pl. 6, fig. 224.

Bulla obstricta GOULD, 1840:196.

tActeocina chowanensis RICHARDS, 1947:34, pl. 11, fig. 10.

Acteocina canaliculata: FRANZ, 1971a:68-69; 1971b:174-182.

Utriculastra canaliculata: MARCUS, 1977:14-17 (in part), figs.
36-38, 40, 42.

Utriculastra canaliculata: MIKKELSEN & MIKKELSEN, 1982:
38.

Cylichnella candeit: MIKKELSEN & MIKKELSEN, 1983:91.

Material examined

Neotype (designated herein): 3.80 mm, ANSP A9721A.

Specimens collected with the neotype: 11L, ANSP
A9721B; 9L, IRCZM 65:1910; 2L, IRCZM 65:1911;
radula slide, IRCZM 65:M@55; 11L, USNM 836099;
10L, ChM IN 19869; 10L, MCZ 272599.

Type material of synonyms:
tActeon wetherilli Lea, 1833: holotype, ANSP 14431.

Miocene (?Pleistocene), New Jersey.

Bulla obstricta Gould, 1840: 14 syntypes (+4 shell frag-
ments), MCZ 216773. New Bedford, Massachu-
setts.

tActeocina chowanensis Richards, 1947: holotype, ANSP
16754. Yorktown Formation, Miocene, North
Carolina.

Other material: Prince Edward Island: 34L, MCZ 38870.—
Maine: Isle au Haut(?): 10E, MCZ ex.14531 (in
part).—Massachusetts: Duxbury: 76L, USNM
358256.—New Bedford: 24L, USNM 57310.—Rhode
Island: Westerly: 200+L, USNM 358281.—Connecti-
cut: Noank (Beebe Cove), 20L, D. Franz Collection.—
New Jersey: Little Egg Harbor: 8E, D. Franz Collec-
tion.—Maryland: Point No Point: 100+L, USNM
379507.—North Carolina: Cape Hatteras: 3L, D. Franz
Collection.—off Cape Lookout: 500+L, USNM
523583.—Neuse River: 51L, UNC-IMS 9859.1-.51.—
South Carolina: Charleston Harbor: 3E, ChM
30.183.11.—Georgia: Jekyll Island: 12E, UNC-IMS
8074.1-12.—Florida: St. Augustine: 18E, USNM
358292 (in part).—Cape Canaveral: 4E, ChM
43.28.4734.—Merritt Island (Pleistocene fossils): 6E,
IRCZM 65:2000.—Turnbull Creek (vouchers): 14L,

Figure 2

Acteocina canaliculata. A. Neotype, 3.80 mm, ANSP A9721A. B. Say’s (1832) original figure. C. Neotype, crawling
animal. D. Map of Charleston, SC, area showing Folly River collection site for the neotype. E. Folly River site

at high tide.

P. S. Mikkelsen & P. M. Mikkelsen, 1984 Page 169

D

32°47'30”

32°37'30"
80°00’

Page 170 The Veliger, Vol. 27, No. 2

P. S. Mikkelsen & P. M. Mikkelsen, 1984

USNM 804403; 22L, IRCZM 65:1671.—Round Is-
land (vouchers): 50L, ROM1Z B2462; 10L, ROM1Z
B2464; 10L, USNM 804404; 10L, IRCZM 65:1672.—
Lantana: 86E, ANSP 180523 (in part).—Miami: 224E,
USNM 270719 (in part).—Rabbit Key, Monroe Co.:
4E, ANSP 105428.—Cape Romano: 8E, ANSP
92061.—Sanibel Island: 84L, MCZ 84334.—Charlotte
Harbor: 68L, USNM 83763.—Clearwater Bay: 117L,
ANSP 9446.—Cedar Keys: 39L, MCZ 242896.—St.
Joseph Bay: 3L, ANSP 83771.—off Ft. Walton: 7L,
MCZ 145871.—Louisiana: Timbalier Island: 27L,
HMNS 9231.—Texas: Galveston: 27L, HMNS 8134.—
Matagorda Bay: 64L, HMNS 9238.—Corpus Christi:
10E, USNM 125553.

Original description

Acteocina canaliculata was originally described from
specimens taken from the coast of South Carolina. The
type locality is believed to be in the vicinity of Charleston,
where the collector, Mr. Stephen Elliott, lived (Mazyck,
1913) and probably did the majority of his collecting. SAy
(1826:211) briefly described the species: “Shell whitish,
immaculate, cylindric, with very minute obsolete wrinkles;
spire convex, very little elevated, mammillated at the tip;
volutions above five, with their shoulder very obtusely
grooved; labrum with the edge arcuated; labium over-
spread with a calcareous lamina, and with a single oblique
fold or small tooth near the base.” Say also stated that
“the arcuated form of the edge of the labrum is only per-
ceived when the part is viewed in profile.” Although a
figure did not accompany the original description, the
species was figured later (as Bullina canaliculata in
“American Conchology” (Say, 1832:pl. 39) and is repro-
duced herein (Figure 2B).

Type material

A series of 25 specimens of Acteocina canaliculata la-
beled as syntypes was procured from the Academy of Nat-
ural Sciences of Philadelphia (ANSP 57312). However,
these are probably not type specimens because: (1) the
specimen label reads “7. canaliculata,” indicating the ge-
nus TJornatina, (2) the cited locality is “Georgia,” and (3)
“J. S. Phillips” is recorded as donor of the lot. Thus, the
status of ANSP 57312 as a type lot is questionable.

A search (by ANSP personnel) of the remaining lots of
Acteocina canaliculata and related species in the ANSP
collections failed to yield the original type material. His-
torical information obtained from Virginia O. Maes (per-
sonal communication, 1982) indicates that the types were
probably destroyed. According to her, Say removed his

Page 171

molluscan collections from the ANSP to New Harmony,
Indiana in 1825 where much of his material was subse-
quently lost in a fire. Long after Say’s death in 1884, his
wife returned whatever was salvaged of Say’s collections
to Dr. H. A. Pilsbry at the ANSP. Unfortunately, no
records exist of the species involved in these transactions,
and we conclude that the types of Volvaria canaliculata
were probably destroyed in the New Harmony fire. To
the best of our knowledge, a neotype has not been desig-
nated.

Lacking any type specimens, one must rely entirely upon
the original description by Say and his subsequent illus-
tration. Unfortunately, the description and figures could
apply to any of several species of Acteocina. However, a
survey of South Carolina material in museum collections
(USNM, ANSP, MCZ, ChM) and from Dr. L. Camp-
bell (University of South Carolina at Spartanburg) in-
cluded only one species living in shallow, estuarine waters
(equivalent to Say’s [1826] “coast of South Carolina’).
This species closely approximates Say’s original illustra-
tion. In addition, the majority of specimens labeled as A.
canaliculata in early museum collections were also of this
same form. We take this as sufficient evidence to consider
the species in South Carolina estuaries to be Say’s Volvaria
canaliculata.

Following the determination of Say’s Volvaria canali-
culata, designation of a neotype was necessary to avoid
future confusion. On December 3, 1982, specimens of Ac-
teocina canaliculata were collected by the authors from soft,
subtidal mud, below zones of Spartina and oysters in the
Folly River, an estuarine channel just south of Charleston
Harbor, Charleston County, South Carolina (Figures 2D-
E). The site was located adjacent to the State Route 171
bridge over the Folly River. Salinity ranged (on an incom-
ing tide) from 27 to 30 ppt during collection of the spec-
imens. The neotype and specimens collected with it were
distributed to various repositories (see Material examined,
above).

A redescription of Acteocina canaliculata follows, based
primarily on our observations of Indian River specimens,
but consistent with material from South Carolina.

Diagnosis

Teleoconch thick-walled, cylindrical to pyriform.
Shoulder rounded; subsutural sculptural band indistinct.
Spire height variable, but usually less than 20% of total
shell length. Protoconch distinctly tapered toward its or-
igin, showing strongly coiled sutures in lateral view. Lat-

Figure 3

Acteocina canaliculata, adults. A. Shell, from Indian River lagoon, in apertural view, 4.58 mm. B. Gizzard plates,
view of grinding surfaces. C. Radula with lateral teeth reflected to expose rachidians. D. Lateral teeth, showing
wing-like expansion with denticles. E, F, and G. Protoconch: E. “Apical” view. F. “Posterior” view. G. “Umbilical”
view. Scales: B = 100 um; C= 10 wm; D = 5 wm; E, F, and G = 50 um.

Page 172

eral radular teeth with wing-like expansion bearing one
row of denticles. Unpaired gizzard plate T-shaped. Tis-
sues of gizzard, pallial caecum, and Hancock’s organs light
orange to pink in live material.

Distribution

Prince Edward Island, Canada; Maine (dead shells
only); Massachusetts to peninsular Florida and entire Gulf
coast to Texas; intertidal to 40 m.

Description
Shell characters

The orthostrophic, dextral teleoconch of adult Acteocina
canaliculata is smooth and cylindrical, and has up to three
whorls (Figure 3A). Large specimens tend toward a pyr-
iform shape, z.e., with greater shell width at the posterior
end. The aperture is narrow posteriorly and flares ante-
riorly; it extends from 80 to 94% of the shell length. The
parietal area bears a slight callus, ending in a columella
with a single fold. The shell walls are porcelaneous white
and thick, approximately 175 um at the midpoint of the
body whorl of adults. The shoulder is somewhat keeled
in young to immature individuals, becoming more round-
ed with maturity, with an indistinct, impressed, subsu-
tural sculptural band. Indian River specimens attained a
shell length and width of 5.0 mm and 2.3 mm respectively;
the specimens varied in spire angle from 76 to 142 degrees
and in spire height from 6 to 20%. The periostracum is
thin and transparent, unless environmentally stained, in
which case it is often spirally banded.

The sutures of the smooth, hyperstrophic, sinistral pro-
toconch (Figures 3E, G) are strongly curved in both “‘lat-
eral” views (7.e., from the larval shell’s umbilical or apical
aspect), appearing slightly umbilicate in “umbilical” view.
In its “posterior” view (Figure 3F), the protoconch tapers
toward its distal end, or origin. The percent of protoconch
protrusion varied from 25 to 74%.

Correlation coefficients (7) were calculated for shell
length versus the four other characters measured (Table
1). Shell length versus shell width showed the strongest
r-value, while percent of protoconch protrusion, percent
spire height, and spire angle yielded very low coefficients.
Percent spire height versus spire angle showed a fairly
strong negative coefficient.

Radular characters

The radular formula of Acteocina canaliculata is 1-R-1
(Figure 3C), with 11-19 rows in specimens 2 mm or more
in length. The rachidian teeth ranged in width from 17
to 34 wm and are centrally notched, with each rounded
half bearing 4-11 sharply pointed denticles. The lateral
teeth (Figure 3D) are sickle-shaped and unicuspid, with

the cusp bearing a wing-like expansion supporting one’

row of several denticles. A blunt, basal tubercle is present
for articulation with adjoining lateral teeth. Ontogenetic

The Veliger, Vol. 27, No. 2

increases were noted in the lateral teeth in number of
denticles from 6 to 18, in width from 41.6 to 71.9 um,
and in angle from 79 to 104 degrees. Variation in number
of lateral tooth denticles within a single radula was also
noted (Figure 3C). Shortly after metamorphosis, lateral
teeth of juveniles were about 15 um in length, and smooth;
faint traces of denticles were evident on some lateral teeth
at 7-9 days post-metamorphosis.

Correlation coefficients (7) for shell length versus rad-
ular characters (Table 1) were generally low, with the
exception of lateral and rachidian tooth widths. Lateral
tooth width versus lateral tooth angle (7 = 0.06) and shell
length versus lateral tooth angle (r = 0.01) were particu-
larly low.

Other features

The extended, living animal of Acteocina canaliculata is
of typical cephalaspid form (Figure 2C). The foot and
mantle are translucent white in color, with scattered
opaque white dots. Although the shell walls are thick and
porcelaneous, they are translucent enough to allow limited
observation of the internal anatomy. The gizzard, pallial
caecum, and Hancock’s organs are light orange to pink in
color.

The calcified portion of the gizzard of Acteocina cana-
liculata consists of three plates (Figure 3B): a “pair” of
non-identical, but similarly elongated, plates opposing a
larger ““unpaired”’ plate. The unpaired plate is most dor-
sal in the crawling animal and is distinctly T-shaped,
regardless of the method of extraction, preparation, or
degree of desiccation.

The reproductive system did not differ in gross arrange-
ment from that described by Marcus (1977) or GOSLINER
S79):

Oviposition

Oviposition in the laboratory occurred at all hours ex-
cept those between 1800 and 2400. Egg masses were usu-
ally deposited within the first few days after collection of
the adults. Spawning occurred monthly in the field and
in the laboratory, giving no indication of reproductive sea-
sonality in the Indian River Lagoon animals.

Egg mass

The egg mass of Acteocina canaliculata (Figure 4A) cor-
responds to “type C” of Hurst’s (1967) opisthobranch
egg mass forms. It is gelatinous and ovoid, ranging in
maximum diameter from 1.9 to 6.4 mm (mean = 3.7 mm).
It is firmly anchored at the sediment surface by a mucous
thread, up to 60 mm long, which may bifurcate one or
more times. Fresh egg masses were usually coated with
sand grains, although most fell off within the first few
hours after deposition. Uncleaved egg diameters ranged
from 63.2 to 85.4 wm (mean = 77.5 wm). The number of
eggs per mass ranged from 189 to 1293 (mean = 631 eggs/

Page 173

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Page 174

mass). Each egg was encased in an oval capsule, about
155 x 130 wm (range: 141-174 x 121-139 wm); capsules
were interconnected by chalazal material. No internal
transparent tubes, nurse eggs, or auxiliary yolk-like ma-
terial were present. Statistical analyses showed high cor-
relation coefficients (7) for maternal shell length versus egg
diameter, egg mass diameter, and number of eggs per mass
(Table 1).

Larval development

Acteocina canaliculata exhibits planktotrophic develop-
ment. Pre-hatching development was rapid and consistent
between egg masses. The first two cleavages, to 2 cells at
2.5 h and to 4 cells at 3.5 h, are total, spiral and equal,
after which they are unequal and form distinct animal
and vegetal poles. The 8-celled stage appears at 4.5 h
followed by the 16-celled stage at 5 h into development.
Further development proceeds rapidly to a multicelled or
blastula stage, and by 23 h to a heart-shaped gastrula
with its slit-like blastopore clearly visible.

The trochophore stage forms, and it begins to spin on
its lateral axis (effectively doing “backwards somer-
saults”) at about 28.5 h into development. The mouth,
metapodial rudiment, and prototroch bearing fine cilia are
clearly visible at this stage, and the vegetal pole appears
as an undifferentiated spherical mass. Two anal cells ap-
pear on the lower right surface of the visceral hump.

The third day of development is characterized by the
appearance of the rapidly spinning veliger stage (Figure
4B). By then, the larva has switched to an antero-posterior
axis of rotation. A well-developed velum with long cilia,
a subvelum, two otocysts, a paucispiral operculum be-
neath a pointed metapodium, a ciliated median metapo-
dial band, and a spherical embryonic shell approximately
85 um in diameter are present. As with other opistho-
branchs, torsion does not occur as a larval process, except
in the migrating anal cells, and the viscera differentiate
in their post-torsional positions. On the 4th day of devel-
opment, the veliger (Figure 4C) has a large, well-formed
right eye. Its shell averages 140 wm long, and is nearly
symmetrical, being only slightly skewed to the larval left.
A colorless, larval kidney is prominent adjacent to the
anus, and cilia are visible within the lumen of the midgut.
Hatching can be mechanically stimulated by handling or
rupturing the egg mass at about 90 h, but if not induced,
will occur by 100-110 h after deposition. Hatching is
rapid and nearly synchronous, being completed (7.e., the
entire mass emptied) within 10 to 20 min.

Post-hatching development depended greatly on the de-

The Veliger, Vol. 27, No. 2

gree of feeding by individual larvae. A large proportion
(77.4%) of the hatched veligers in our most successful
culture did not metamorphose; most of these were appar-
ently unable to feed, as evidenced by their colorless diges-
tive systems and little or no growth. The remaining in-
dividuals (22.6%) began feeding immediately, as evidenced
by the bright green coloration of their guts, and developed
rapidly. Acquisition of juvenile characteristics after hatch-
ing was a function of the degree of growth, expressed as
shell length, rather than age of the specimen. The degree
of development among the individuals in a culture was
also highly variable.

When larvae were not fed, many individuals survived
for two weeks although no shell growth was observed.
Although the left eye appeared in some individuals after
four days, it remained smaller than the first-formed right
eye. The left digestive diverticulum noticeably decreased
in size during this period. All starved larvae died by the
third week after hatching.

In feeding individuals, the left eye appeared, and equaled
the right in size, by the fourth post-hatching day at 163
um shell length. By 270 um shell length, the propodium
began to swell, the right side of the mantle opened, and
the larval heart began pulsating.

Metamorphosis at 300 wm shell length (Figures 5A-C)
began after 14 to 20 days, independent of any special
substrate. In newly metamorphosed individuals, both lar-
val and adult hearts beat actively, and the nearly umbil-
icate aspect of the shell was visible from the larval right
(Figure 5A). Immediately after metamorphosis, shell
growth accelerated at the larval right, beginning the change
in direction of coiling. Shells of juveniles approximately
one week post-metamorphosis are shown in Figures 5D
and E. Attempts at rearing A. canaliculata juveniles past
this stage of development were unsuccessful.

Remarks

Specimens of Acteocina canaliculata show a strong re-
semblance to those of Retusa obtusa (Montagu, 1803), es-
pecially in New England where the two species overlap
in distribution. Living or live-collected material of R. ob-
tusa may be distinguished from A. canaliculata by the pres-
ence of a much thinner shell and by the absence of eyes
and a radula. In the chalky condition often found in dead
shells, however, the two species are more similar in ap-
pearance, and one must rely upon conchological charac-
ters alone. The bulbous protoconch of R. obtusa, indicating
direct development, is the most reliable feature in these

Figure 4

Acteocina canaliculata, larval development. A. Egg mass. B and C. Larval stages showing appearance of larvae and
corresponding larval shells. B. Early veliger in egg capsule, three days post-deposition. C. One-eyed veliger at
hatching, four days post-deposition. Scales: B and C = 20 um.

P. S. Mikkelsen & P. M. Mikkelsen, 1984 Page 175

Page 176

cases. Retusa obtusa also usually exhibits an umbilical chink
and a weaker or absent columellar fold.

The maximum shell length of 9 mm for Acteocina ca-
naliculata, given by Marcus (1977:14) and others, is in
error, being attributable to Bulla canaliculata d’Orbigny,
1841, a probable synonym of Tornatella bullata Kiener,
1834.

Although current literature (ABBOTT, 1974) character-
izes Acteocina canaliculata as a shallow-water, estuarine
species, this viewpoint was derived from the incorrect re-
sults of WELLS & WELLS (1962). Our examination of live-
collected museum specimens determined wider ecological
and bathymetric ranges—from estuarine to oceanic, and
from intertidal to a depth of 40 m.

Acteocina chowanensis Richards, 1947, is herein syn-
onymized with A. canaliculata for the first time, based on
examination of type material. Tornatina coixlachryma
Guppy, 1867, is herein removed from synonymy with A.
wetherilli (=A. canaliculata), as stated by DALL (1890) and
PILsBRY (1921). The neotype of 7. coixlachryma (USNM
369322), designated by WoOoDRING (1928), has a proto-
conch indicating direct development and spiral striae over
the entire teleoconch; it does not agree in morphology with
any of the species discussed herein.

In his synonymy of Bulla (Tornatina) Wetherelli [sic],
DE GREGORIO (1890) listed “=?(1887. Tornatina crassi-
plicata Conr. Meyer ...).” This refers to Bulla crassiplica
Conrad, 1847, and to MEYER’s (1887) listing and figure
of that species. Both Meyer’s figure and the lectotype
(ANSP 13412) and paralectotypes (ANSP 13413) of B.
crassiplica exhibit cylindrical shells with keeled shoulders
around low to nearly involute spires. This is very different
from A. wetherilli; therefore, we also remove B. crassiplica
from synonymy with A. wetherilli.

FRANZ’s (1971b) observations on larval development of
Acteocina canaliculata from Connecticut compare well with
our observations from eastern Florida. Franz noted ovi-
position only at night, while Florida specimens oviposited
from 2400 to 1800; he also noted a smaller range (250-
700) in the number of eggs per mass. Franz found sand
grains adhering to the newly deposited egg mass; we ob-
served this also, but found that most of the sand grains
fell off within a few hours after deposition. Floridian A.
canaliculata egg capsules were generally smaller, as was
the diameter of the uncleaved ovum. The larval shell, at
hatching, was also slightly smaller in Floridian specimens.
Shell length at metamorphosis in Florida was identical to
that found in Connecticut; however, metamorphosis oc-
curred after 14 to 20 days post-hatching in Florida, twice
as long as in Connecticut.

The Veliger, Vol. 27, No. 2

Acteocina candei (d’Orbigny, 1841)
(Figure 6)

Bulla candei D’ORBIGNY, 1841:128-129; 1842:pl. 4 bis, figs.
1-4.

tActeocina anetaspira WOODRING, 1928:121-122, pl. 2, fig.
6

tActeocina canaliculata vaughani GARDNER, 1948:278-279
pl. 38, figs. 5-6.

Acteocina candei: WELLS & WELLS, 1962:87-93 (in part);
figs. 4, 7-10, 12.

tActeocina elachista WOODRING, 1970:418, pl. 62, figs. 1-2.

?

Material examined

Lectotype (designated herein): 3.28 mm specimen, BM(NH)
1854.10.4.17 (in part).
Paralectotypes (designated herein): 2.61 mm and 2.25 mm
specimens, BM(NH) 1854.10.4.17 (in part).
Type material of synonyms:
tActeocina anetaspira Woodring, 1928: holotype, USNM
369321. Bowden Formation, Miocene, Jamaica.
TActeocina canaliculata vaughani Gardner, 1948: holo-
type, USNM 497059. Waccamaw Formation, Plio-
cene, North Carolina.
tActeocina elachista Woodring, 1970: holotype, USNM
646052. Gatun Formation, Miocene, Canal Zone.
Other material: North Carolina: off Cape Hatteras: 14E,
USNM 322831.—off Cape Lookout: 4L, UNC-IMS
9278.1-4.—South Carolina: 5L, R. Van Dolah Collec-
tion.—Georgia: off Savannah: 7E, UNC-IMS 7544.1-
7.—Florida: off St. Augustine: 1E, IRCZM 65:1943.—
off Miami: 2E, USNM 358309 (in part).—‘Tortugas’:
26L, USNM 358304 (in part).—off Sanibel Island: 4E,
MCZ 245063.—off Calhoun County: 7E, ANSP
83825.—Alabama: off Mobile: 4E, USNM 323745.—
Texas: off Galveston: 1L, HMNS 8133; 3E, HMNS
9266.—Greater Antilles: Northwest Cuba: 76L, USNM
358210 (in part).—Jamaica: 11E, USNM 442626.—
Haiti: 2E, USNM 383220 (in part).—Lesser Antilles:
British Virgin Islands: 6L, ANSP 338601.—Antigua:
23E, USNM 500363 (in part).—Barbados: 17E,
USNM _ 500360 (in part).—Grenada: 24E, ANSP
296954.—Bonaire: 7E, ANSP 351033.—Central Amer-
ica: Yucatan: 6E, USNM 323195.—Belize: 1E, ANSP
20656.—Limon Bay, Panama: 1E, USNM 760350.—
South America: Cabo Orange, Brazil: 13E, MORG
21.811.—Fernando de Noronha, Brazil: 12E, MORG
20.608.—Sao Paulo, Brazil: 31L, MORG 21.743.—
Uruguay: 8E, MORG 20.070.—San Antonio, Argen-
tina: 17E, MORG 17.917.

Original description

D’ORBIGNY (1841:128-129) originally described shells
of Bulla candei as “oval, oblong, thick, slightly narrowing

Figure 5

Acteocina canaliculata, post-larval development. A, B, and C. Shell at metamorphosis. D and E. Shells at approx-

imately one week post-metamorphosis. Scale = 50 um.

P. S. Mikkelsen & P. M. Mikkelsen, 1984

The Veliger, Vol) 275 Now

Page 178

P. S. Mikkelsen & P. M. Mikkelsen, 1984

anteriorly, smooth, bright, marked slightly by a few lines
of growth. Spire prominent, conical, canaliculate on the
suture, aperture narrow, ending in a point posteriorly,
very enlarged anteriorly, and supplied, on the columella,
with a ridge resembling a tooth. Color uniformly white.”
d’Orbigny also described the general appearance of the
hyperstrophic protoconch. No distinction was made be-
tween B. candei and the earlier described Volvaria cana-
liculata.

Type material

The type material of Bulla cande: (Figures 6A, C) con-
sists of three specimens (3.1, 2.5, and 2.1 mm lengths)
glued to a strip of black paper. All three have intact pro-
toconchs and appear to have been dead-collected. A fourth
specimen originally part of the lot was found to be missing
in 1982 by BM(NH) personnel, but is believed to have
been the smallest of the four based on the size of its
impression in the glue. We herein designate the largest
specimen of the remaining three as lectotype (Figure 6A),
because it most closely approximates d’Orbigny’s illustra-
tion (1842:pl. IV bis, figs. 1-4; reproduced herein, Figure
6D) as well as the dimensions (3 mm long by 2 mm wide)
given in the original description (D’ORBIGNY, 1841). The
two smaller specimens are herein designated as paralec-
totypes. The type locality was given as the “Antilles.”

Diagnosis

Shell, radula and gizzard plates as in Acteocina canali-
culata, except: subsutural sculptural band strongly im-
pressed with distinct axial ribbing; spire height usually
greater than 20% of total shell length; shell shape more
uniformly cylindrical.

Distribution

Cape Hatteras to peninsular Florida and entire Gulf
coast to Texas; throughout the Caribbean, including the
Greater and Lesser Antilles, coasts of Central America
and South America to San Antonio, Argentina; recorded
from 3 to 42 m.

Remarks

Acteocina candei is primarily an offshore species. From
the appearance of its protoconch, it is probably planktic-
developing. The adult shell is extremely similar to that of
the planktic-developing, congener A. canaliculata. We are
unable to distinguish the two species on the basis of shell

Page 179

thickness, radula, gizzard plates, or gross reproductive
anatomy. The only consistent diagnostic character for A.
candei is the presence of a strongly impressed, and usually
ribbed, subsutural band of sculpture (Figure 6F), appar-
ently what D’ORBIGNY (1841) meant by ‘“‘canaliculate on
the suture.” This subsutural band of sculpture is as reli-
able a conchological character to separate A. candei from
A. canaliculata as are the involute spire and double colu-
mellar fold used to distinguish A. bidentata (D’ORBIGNY,
1841) from either A. candei or A. canaliculata (all three
species have extremely similar radulae and gizzard plates).
Acteocina candei also usually exhibits a more uniformly
cylindrical (7.e., less pyriform) shell shape, greater spire
height, and a more highly protruded protoconch.

Acteocina candei and A. canaliculata were synonymized
by Marcus (1977). According to her illustrations, MARCUS
(1977:figs. 39, 42a), also included a third species (de-
scribed as new below). Whether both A. canaliculata and
A. candei were actually present in Marcus’ material can-
not be reliably determined from her text or illustrations.
The subsutural sculptural band below the suture in A.
candez is distinct, consistent, and comprises a good specific
character in our opinion. This is perhaps the same feature
noted by D’ORBIGNY (1841) as “canaliculate on the su-
ture,’ and by DALL (1922:96) as “‘channel at the suture.”
However, Dall probably considered specimens of both A.
candei and A. canaliculata in observing that the ‘‘channel”’
varied from “clear-cut and sharp” (=A. candez) to “‘ob-
solete” (=A. canaliculata). Because of this distinct sculp-
tural feature, we resurrect A. candei from synonymy, giv-
ing it full specific status. Until living specimens of A.
candei can be further studied, the relationship between it
and A. canaliculata is uncertain. Therefore, only a prelim-
inarily revised diagnosis and distribution for A. candei are
given herein; detailed description awaits more complete
study.

Based on examination of their type material, the fol-
lowing fossil species are herein synonymized with Acteo-
cina candei: Acteocina anetaspira Woodring, 1928 (synon-
ymy previously suggested by WOODRING [1970]); Acteocina
canaliculata vaughani Gardner, 1948; and Acteocina elach-
ista Woodring, 1970.

Acteocina atrata
Mikkelsen & Mikkelsen, spec. nov.
(Figures 7-10)

Retusa canaliculata: WELLS & WELLS, 1962:87-93.
Utriculastra canaliculata: MARCUS, 1977:14-17 (in part), figs.
39, 42a.

Figure 6

Acteocina candei. A. Lectotype, 3.28 mm, BM(NH) 1854.10.4.17 (in part). B. Shell from offshore of Indian River
region, 2.89 mm. C. Syntypes, BM(NH) 1854.10.4.17, glued to a strip of black paper; lectotype is at extreme left.
D. D’ORBIGNY’s (1842) original illustration. E. Same as B, “apical” view of protoconch. F. Same as B, posterolateral
view of shoulder, showing sculptured subsutural band. Scales: E = 50 wm; F = 100 um.

Page 180

Utriculastra canaliculata: MIKKELSEN & MIKKELSEN, 1982:
38 (in part).

Cylichnella canaliculata: MIKKELSEN & MIKKELSEN, 1983:
91.

Material examined

Holotype: (Figures 7A, B), 3.72 mm, USNM 838029.

Paratypes: 25 each to USNM 838030, ANSP A 10112,
MCGZ 294223, IRCZM 65:1996, BM(NH) 1983098,
UNC-IMS 9860.1-.25, HMNS 13002, CAS 035945,
and MORG 22.549.

Type locality: Indian River lagoon, Indian River County,
Florida; in shallow, subtidal mud east of Round Island,
on the eastern side of the lagoon (Figures 7C, D),
27°33.53'N latitude, 80°09.91'W longitude. Salinity at
the time of collection was 17 ppt.

Other material: Florida: St. Augustine: 10E, USNM 358292
(in part).—Turnbull Creek (vouchers): 11L, USNM
836098; 3L, IRCZM 65:2001.—Haulover Canal area
(vouchers): 10L, ROM1Z B2463.—Merritt Island
(Pleistocene fossils): 8E, USNM 371722; 8E, IRCZM
65:1999; 8E, PRI 30017a—h.—Round Island (vouch-
ers): 24L, ROM1Z B2461.—Lantana: 61E, ANSP
357893.—Miami area: 193E, USNM 270719 (in
part).—Sanibel Island: 70E, MCZ 282080-b.—Sara-
sota: 7E, USNM 36019.—Clearwater area: 2L, ANSP
357892.—Tampa Bay: 21E, ANSP 356485.—Cedar
Keys: 13L, USNM 36020 (in part).—off Ft. Walton:
3E, MCZ 282779.—Bahamas: Great Abaco: 2E, ANSP
299498.

Diagnosis

Teleoconch thin-walled, cylindrical. Shoulder keeled,
with a distinct subsutural, sculptural band. Protoconch
globose, showing nearly straight suture in lateral view.
Lateral radular teeth with one row of denticles directly
on inner carinate edge of cusp. Unpaired gizzard plate
heart-shaped. Tissues of gizzard, pallial caecum, and
Hancock’s organs black.

Etymology

The specific name atrata, from the Latin atratus, means
“clothed in black” and refers to the black pigment present
on various tissues of the living animal.

Distribution

Both sides of peninsular Florida; Bahamas (one record
of dead shells from Great Abaco); less than 2 m. Uncon-

The Veliger, Vol. 27, No. 2

firmed literature record from Pamlico Sound, North Car-
olina (WELLS & WELLS, 1962).

Description
Shell characters

The heterostrophic shell of Acteocina atrata (Figure 8A)
consists of a smooth, hyperstrophic, sinistral protoconch,
followed by a cylindrical, orthostrophic, dextral teleoconch
with up to three whorls in adults. The teleoconch is off-
white, smooth, translucent, and more thinly shelled than
that of A. canaliculata, with the shell wall approximately
112 um thick at the midpoint of the adult body whorl.
The shell is angulate or keeled at the shoulder, and shows
a prominent subsutural sculptural band. The aperture
extends from 78 to 97% of the shell length, and flares
widely at the rounded to truncate anterior end. In Indian
River material, the shells reached a maximum length and
width of 5.4 mm and 2.7 mm respectively, and varied in
spire angle from 80 to 160 degrees and in spire height
from 3 to 22%. Large shells (3 mm and over) showed a
strong tendency for the last whorl to be set at an abnor-
mally high level on the body whorl, thus decreasing the
expected final spire height and increasing the expected
final spire angle. Periostracum as in A. canaliculata. The
protoconch (Figures 8E-G), when viewed “laterally”
(either from the larval shell’s umbilical or apical aspect)
exhibits an only slightly curved suture. From its posterior
view (Figure 8F), the protoconch is globose and does not
taper. The percent of protoconch protrusion varied from
27 to 70%.

Correlation coefficients (7) for shell characters (Table
1) followed a pattern similar to those for Acteocina cana-
liculata.

Radular characters

The radular formula of Acteocina atrata is 1-R-1, with
14-19 rows in specimens 2 mm or more in length. The
rachidian teeth are centrally notched, with each rounded
half bearing 5-11 sharply pointed denticles. The width of
the rachidian teeth ranged from 24 to 39 um. The lateral
teeth (Figures 8C, D) are distinct from A. canaliculata,
being sickle-shaped, unicuspid, and bearing one row of
finer denticles directly on the cusp’s inner carinate edge.
A blunt basal tubercle is present for articulation with
adjoining lateral teeth. The lateral teeth varied ontoge-
netically in number of denticles from 14 to 25, in width
from 46.8 to 97.8 wm, and in angle from 98 to 125 degrees.

Figure 7

Acteocina atrata, spec. nov. A. Holotype, 3.72 mm, USNM 838029. B. Same as A, crawling animal. C. Round
Island cove, the type locality of A. atrata. D. Map of the central east coast of Florida, showing primary collection
sites (dots); detailed insert shows type locality (star), east of Round Island and north of the Indian River County/

St. Lucie County line.

P. S. Mikkelsen & P. M. Mikkelsen, 1984 Page 181

RIVER —
BANANA RIVER

INDIAN
RIVER

INLET

SEBASTIAN

ATLANTIC
OCEAN

mA FT. PIERCE INLET

ST. LUCIE INLET

Page 182 The Veliger, Vol. 27, No. 2

P. S. Mikkelsen & P. M. Mikkelsen, 1984

Variation within a single radula was also noted, especially
in number of lateral tooth denticles. Hatchlings possessed
radulae with 4-5 denticles per lateral tooth, increasing to
6 denticles in 14-20 days. These denticles are of the same
form as those in the adult specimens, located directly on
the inner carinate edge of the cusp; no wing-like expan-
sion supporting the denticles, as is present in A. canali-
culata, was seen at any stage of development.

Correlation coefficients (7) for shell length versus rad-
ular characters (Table 1) were generally low, with the
exception of lateral and rachidian tooth widths, as in Ac-
teocina canaliculata. However, lateral tooth width versus
lateral tooth angle (7 = 0.60) was an order of magnitude
higher than in A. canaliculata; shell length versus lateral
tooth angle was also notably higher.

Other features

The foot and mantle coloration in living Acteocina atra-
ta is similar to A. canaliculata. The thinly walled adult
shell of A. atrata allows visual observation of a portion of
the internal anatomy, enhanced in this species by the pres-
ence of black pigment (absent in A. canaliculata) in the
tissue over the gizzard and the pallial caecum (Figure 7B).
Black pigment is also visible in the lateral groove between
the cephalic shield and the propodium, in the vicinity of
Hancock’s organs.

The gizzard plates of Acteocina atrata are similar to
those of A. canaliculata, except that the unpaired plate is
distinctly heart-shaped (regardless of method of extrac-
tion, preparation, or degree of desiccation).

Gross reproductive anatomy was examined and found
not to differ from that described by Marcus (1977) and
GOSLINER (1979) for Acteocina canaliculata. Preliminary
observations by T. M. Gosliner (personal communication,
1983) determined differences in penial morphology be-
tween A. atrata and A. canaliculata.

Oviposition

Oviposition occurred in a time frame identical to that
of Acteocina canaliculata. Spawning occurred monthly in
the field and in the laboratory, giving no indication of
reproductive seasonality in the Indian River lagoon.

Egg mass

The egg mass of Acteocina atrata (Figures 9A, A’) is
very similar in general shape and size to that of A. cana-
liculata. It is also gelatinous, ovoid to spherical (from 2.3

Page 183

to 5.0 mm in maximum diameter, mean = 3.5 mm), and
is anchored at the sediment surface by a mucous thread.
When freshly deposited; the egg masses were always
heavily coated with sand grains, which persisted for most
of the developmental period, but most of which dropped
off during the last 1-2 days before hatching. The un-
cleaved egg diameter ranged from 132.3 to 175.9 wm
(mean = 151.6 wm), and each mass contained from 23 to
148 eggs (mean = 91.1 eggs/mass). Each egg was enclosed
in an oval capsule about 320 x 262 um (range: 268-347
um X 235-288 wm). The capsules were interconnected by
chalazal material, and were also loosely packed into trans-
parent tubes, 427.0-807.7 um in diameter (mean = 609.4
um), irregularly coiled within the egg mass. There were
no nurse eggs or auxiliary yolk-like material.

In contrast to Acteocina canaliculata, statistical analyses
showed low correlation coefficients (7) for shell length ver-
sus egg diameter, mass diameter, and number of eggs/
mass (Table 1).

Larval development

Acteocina atrata exhibits capsular metamorphic devel-
opment (as defined by Bonar, 1978). Although the time
between developmental stages varied among egg masses,
development within an individual mass was well synchro-
nized. Early cleavages resulted in a 2-celled stage at 3 h,
4 cells at 4h, 8 cells at 5 h, and 16 cells at 6 h. Further
development proceeded rapidly to a multicelled or blastula
stage, and then to the heart-shaped gastrula by 20 to 25
h into development.

During the second 24-h period, the trochophore stage
appears and begins to spin on its antero-posterior axis,
40-45 h into development. The mouth, metapodial rudi-
ment, and prototroch bearing fine cilia are clearly visible
at this stage; the vegetal pole appears as an undifferen-
tiated spherical mass. Two anal cells are present on the
lower right surface of the visceral hump.

The third day after deposition is characterized by a
rapidly spinning, early veliger stage (Figures 9B, B’). A
cone-shaped shell, 177 wm in length, has formed with its
apex at the veliger’s left. The velum is well formed, with
a strong median elevation. The anal cells have migrated
to a position below the lower right edge of the velum. A
median ridge is evident on the rounded metapodium, and
the operculum is visible at the edge of the foot. The viscera
have begun to separate within the visceral hump.

By the fourth day, continued growth has modified the
conical aspect of the larval shell, seemingly decreasing its

Figure 8

Acteocina atrata, spec. nov., adults. A. Shell from Indian River lagoon in apertural view, 4.18 mm. B. Gizzard
plates, view of grinding surfaces. C. Outer edge of lateral radular teeth showing basal tubercle. D. Inner edge of
lateral teeth showing denticles. E, F, and G. Protoconch: E. ‘“‘Apical” view. F. ‘‘Posterior” view. G. ‘Umbilical’
view. Scales: B = 100 um; C and D = 5 um; E, F, and G = 50 um.

Page 184 The Veliger, Vol Zia

B

P. S. Mikkelsen & P. M. Mikkelsen, 1984

length to 165 wm. The direction of coiling from this point
onward is decidedly skewed to the larval right. Spinning
has slowed from the previous day, but continues steadily.
The propodium has begun to expand. The digestive or-
gans are clearly differentiated, as is a large, and now fully
functional, retractor muscle on the larval left. The tor-
sional process is represented solely by the migration of the
anal cells, as in Acteocina canaliculata.

On day five, motion has slowed drastically although the
larvae (Figures 9C, C’) continue to turn, now frequently
changing direction of rotation. The velar lobes are still
fully extended, with the single row of fine preoral cilia
erect and beating. No postoral band, or subvelum, has
developed nor will develop in this species. The propodium
has continued to develop and the median metapodial band
is now a strong keel. A pair of otocysts has appeared in
the base of the foot. A small right eye is visible.

The continued decrease of spinning movement and the
appearance of the left eye, initially smaller than the right,
occur on day six. As the larva stops rotation by day seven,
the larval heart (at the center of the larva, just dorsal to
the foregut) begins to pump. A mantle opening appears
to the right of the cephalic area; at its edges beat cilia
longer than those of the velum. Also as rotation ceases,
the velum becomes reduced to form the cephalic shield of
the juvenile snail, with its row of fine cilia still visible.
The propodium is well inflated and nearly equal in size
to the metapodium.

The larva of eight days, with a shell length of 260 um,
nearly fills its egg capsule, and spends much time fully
retracted. A radula of four rows is present, with about
four denticles on each lateral tooth. The osphradium and
the two-chambered adult heart have formed in the mantle,
appressed to the interior right side of the shell. As the
continuous crawling movements that precede hatching be-
gin on day nine, 200-210 h after deposition, the adult
heart begins to beat. The egg capsules appear thin and
weakened by this time, and the larvae break through them
to crawl freely within the egg tubes. Nearly all of the
larvae will have hatched from their capsules before breaks
in the tubes and mass are located and benthic life can
begin. At hatching (Figures 10A-D), shell length is 300
um, the larval retractor muscle and operculum are still
present, and there is no evidence of gizzard plates. In
lateral view (Figure 10D), the short and only slightly
curved suture line of the larval shell is distinct.

Immediately after hatching, shell growth becomes ac-
celerated at the larval right, beginning the change in di-
rection of coiling. The teleoconch first appears within the

Page 185

apertural edge of the protoconch, creating a distinct su-
ture. At the larval left, the leading edge of the teleoconch
is still internal four days after hatching (Figures 10E, F).
Starved hatchlings of similar age showed no trace of te-
leoconch growth. The operculum is lost during the second
post-hatching week, and the black pigment characteristic
of Acteocina atrata appears during the sixth week, at 0.75
mm shell length.

During the first 2-3 weeks after hatching, when the
transition from sinistral to dextral coiling takes place, the
increase in shell length is slow, gaining only about 0.01
mm/week. When this transitional phase of growth is com-
pleted, shell length increases at a mean rate of 0.11 mm/
week under laboratory conditions; this rate of growth con-
tinues until a shell length of about 2.5 mm has been at-
tained, approximately 23 weeks after hatching. At this
time, increase in shell length again slows considerably.

Remarks

There is a possibility that Acteocina atrata is not prop-
erly placed in the genus Acteocina, because of distinct dif-
ferences in the lateral radular teeth, specifically the ab-
sence of the denticle-bearing “wing.” In this regard, the
lateral teeth of A. atrata more closely approximate those
of the types of Tornastra and Paracteocina Minichev, 1966
(see Marcus, 1977), than they do those of the type of
Acteocina. Therefore, generic placement of A. atrata in
Acteocina may be tentative, pending generic revision of the
group.

Fossil specimens of Acteocina atrata have been recently
discovered at a canal excavation site on Merritt Island,
Brevard County, Florida. The Pleistocene fossiliferous
layer was approximately 1.8 m under the surface. The
specimens were found with roughly equal numbers of A.
canaliculata. The venerid bivalve Parastarte triquetra (Con-
rad, 1846) was also present in great numbers, paralleling
Recent conditions in the Indian River lagoon.

The development of Acteocina atrata is similar to that
of Retusa obtusa, the only other cephalaspid with well-
documented capsular metamorphic development (see
SMITH, 1967a, b; BONAR, 1978). However, there are no-
table differences (A. atrata versus R. obtusa): a smaller
egg diameter (151.6 versus 245 wm) and a greater number
of eggs per mass (means of 91.1 versus 33 eggs, and max-
ima of 148 versus 46). In A. atrata, the entire develop-
mental progression toward hatching is greatly accelerated
at all stages. Hatching in A. atrata occurs 3.2 times faster:
9 days versus 29 in R. obtusa. Several anatomical differ-

Figure 9

Acteocina atrata, spec. nov., larval development. A. Egg mass with sand coating. A’. Same as A, enlarged slightly,
with sand removed. B and C. Larval stages showing appearance of larvae corresponding to larval shells. B. Early
veliger in egg capsule, three days post-deposition. B’. Same as B, shell only. C. One-eyed veligers in capsules, five
days post-deposition. C’. Same as CG, shells only. Scales: B and B’ = 15 um; C and C’ = 50 um.

The Veliger, Vol. 27, No. 2

P. S. Mikkelsen & P. M. Mikkelsen, 1984

Table 2

Page 187

Distinguishing characteristics of Acteocina canaliculata, A. atrata spec. nov., and A. candeu.

Egg mass

Development

Trochophore
Veliger

Shell

Protoconch
Gizzard

Lateral radular teeth

Acteocina canaliculata

Sand-free
Tubes absent
Many (>150) small eggs

Planktotrophic

Florida: Hatch on day 4,
settle on day 24

Connecticut: Hatch on day 4,
settle on day 14-20

Spins on lateral axis

Spherical early embryonic shell

Pointed foot

Subvelum present

Long velar cilia

Pyriform

Rounded shoulder

Thick-walled (175 um)

Tapered

Curved suture
Pink-pigmented

T-shaped unpaired plate
Denticles on wing of cusp
Few denticles: 6-18 in adults

Acteocina atrata

Sand-covered

Tubes present

Few (<150) large eggs

Capsular metamorphic

Hatch on day 9, as benthic juveniles

Spins on antero-posterior axis
Cone-shaped early embryonic shell
Rounded foot

Subvelum absent

Short velar cilia

Cylindrical

Keeled shoulder

Thin-walled (112 wm)

Globular

Straight suture

Black-pigmented

Heart-shaped unpaired plate
Denticles directly on cusp edge
Many finer denticles: 14-25 in adults

Acteocina candei
?
?
?

Planktic (?)
a

?
?
?
?
?

Cylindrical
Sculptured shoulder
Thick-walled

Tapered

Curved suture

Not pigmented (?)
T-shaped unpaired plate
Denticles on wing of cusp
Few denticles

ences are also apparent. The initial appearance of the
shell in the R. obtusa veliger is rounded and globular
(SMITH, 1967b), not distinctly cone-shaped as in A. atrata.
The larval kidney adjacent to the anus and the ciliated
mid-velar groove of R. obtusa are both absent from A.
atrata larvae. Also, the right larval retractor muscle of R.
obtusa, composed of various muscle fibers to the right pos-
terior interior of the shell, was not noted in A. atrata,
although numerous small bundles attached to various dor-
sal and posterior locations were present. In addition, the
prominent eyes, presence of a radula, pulsating larval heart,
and median metapodial keel of A. atrata were not noted
by SMITH (1967b) for R. obtusa.

Although we once considered the possibility of poecilog-
ony for Acteocina canaliculata, the consistent differences in
egg, larval, and adult characters (Tables 2, 3) indicate the
definite presence of two distinct species. Preliminary elec-
trophoretic examination (unpublished data, M. J. Hara-
sewych, January 1983) of A. canaliculata and A. atrata
has shown strong and consistent differences in their ester-
ase systems, with strong tendencies in other enzyme sys-
tems as well.

DISCUSSION

Because most lots of Acteocina canaliculata in early mu-
seum collections are now known to have been correctly
identified, the recent taxonomic confusion between A. ca-
naliculata and A. cande: apparently stems from WELLS &
WELLS (1962). Although their conception of A. candei was
correct, their ‘““Retusa canaliculata”’ was in fact A. atrata;
the true A. canaliculata seems to have been excluded en-
tirely. FRANZ (1971b:181) was correct in his identification
as well as in his belief that Wells & Wells’ observations
of direct development in A. canaliculata were for “some
other cephalaspid.”” Our own earlier work reflects the
taxonomic problems initiated by WELLS & WELLS (1962)
and augmented by Marcus (1977), who considered Ac-
teocina canaliculata, A. candei, and A. atrata, all as a single
species. While considering Marcus’ synonymy valid, we
(MIKKELSEN & MIKKELSEN, 1982) determined ‘A. can-
dev” (actually A. canaliculata) to be a juvenile form of “A.
canaliculata” (actually A. atrata). This incorrect result is
now known to have been influenced by the coincidental
lack at that time of large specimens of A. atrata. After

Figure 10

Acteocina atrata, spec. nov., post-larval development. A, C, and D. Shell at hatching. B. Appearance of hatchling
corresponding to shell in A. E and F. Shells at four days post-hatching, showing unequal growth of teleoconch.

Scales: A-D = 50 um (marker at B); E and F = 25 um.

Page 188

‘Table 3

Results of ¢-tests to determine distinctness of the means of

character distributions between Acteocina canaliculata and

A. atrata spec. nov. (* indicates characters useful in dis-
tinguishing these species).

Significantly distinct Significantly indistinct

Character P< Character P<
Spire angle 0.0001 Shell length 0.7627
Spire height 0.0022 Shell width 0.1755
Radular rows 0.0003 % Protoconch
Lateral tooth protrusion 0.7895

denticles 0.0000 Egg mass diam-
Rachidian tooth eter 0.2929
denticles 0.0010
Lateral tooth
width 0.0000
Rachidian tooth
width 0.0000
Lateral tooth
angle 0.0000
*Number of eggs 0.0000
*Egg capsule
length 0.0000
*Ege capsule
width 0.0009
*Ege diameter 0.0000

SHELL
LENGTH

SPIRE
HEIGHT

PERCENT:

SPIRE
ANGLE

DEGREES:

PROTOCONCH
PROTRUSION

PERCENT: ,20

The Veliger; Vol 27 onZ

larval development studies had convinced us of the pres-
ence of two distinct species (while still confusing the
names), we suggested the resurrection of A. candei as a
valid species (MIKKELSEN & MIKKELSEN, 1983). It was
not until type material was examined that we determined
the distinct characteristics for these species, and the correct
identifications of our specimens.

Our search for previous names for Acteocina atrata in-
cluded investigation of Bulla pusilla Pfeiffer, 1840. Per-
sonnel of the British Museum (Natural History) and the
Museum fiir Naturkunde der Humboldt-Universitat zu
Berlin agreed that Pfeiffer’s types were probably de-
stroyed in the Stettin museum during World War II. This
opinion was also held by DANCE (1966:197, 285). The
Humboldt museum located a lot of 33 specimens of “Bulla
pusilla” from Cuba in R. W. Dunker’s collection, which
were presumably obtained from Pfeiffer. This lot included
32 specimens of Acteocina candei and one specimen of a
species of Acteon. However, in view of the uncertain status
of this lot, the lack of definite type material, and the am-
biguity of the original description, it is unknown what
Pfeiffer intended to be called Bulla pusilla and the name
must be considered a nomen dubium.

Analysis of Acteocina canaliculata and A. atrata from
the Indian River lagoon showed overlap of all shell and
radular meristic and morphometric characters (Figures
11, 12). Results of t-tests (Table 3) showed some signifi-
cantly distinct means of the character distributions; how-

Figure 11

Variation in shell characters of Acteocina canaliculata (stippled; n = 56) and A. atrata (cross-hatched; n = 49).
Ranges (horizontal solid line), means (vertical mid-point of pattern), and + SD (pattern) are plotted.

P. S. Mikkelsen & P. M. Mikkelsen, 1984 Page 189

RADULAR
ROWS
NUMBER:
LATERAL

TOOTH
DENTICLES

NUMBER:

RACHIDIAN
TOOTH
DENTICLES,

NUMBER:

LATERAL
TOOTH
WIDTH
AM:

RACHIDIAN
TOOTH
WIDTH
AM:

LATERAL
TOOTH
ANGLE

DEGREES:

Figure 12

Variation in radular characters of Acteocina canaliculata (stippled; n = 56) and A. atrata (cross-hatched; n = 49).
Symbols as in Figure 11.

MASS
DIAMETER
MM:

TUBE
DIAMETER
jim: 4400

CAPSULE
LENGTH
AM:

CAPSULE
WIDTH

GG
DIAMETER
Am: 6

EGGS PER
MASS

NUMBER:

Figure 13

Variation in eggs and egg mass characteristics of Acteocina canaliculata (stippled) and A. atrata (cross-hatched).
Symbols as in Figure 11.

Page 190

ever, because of the overlap of the ranges, these characters
cannot be reliably used in specimen identification. Con-
sistent subjective differences do exist in the sculpture of
the shoulder, the shape of the protoconch, the presence or
absence of black pigment on the animal, the placement of
lateral tooth denticles, and the shape of the unpaired giz-
zard plates. However, distinct meristic and morphometric
differences exist in the characteristics of the eggs and egg
capsules (Figure 13, Table 3).

The distinguishing characters for Acteocina canaliculata,
A. atrata, and A. candei are summarized in Table 2. The
most useful of these in the routine sorting of samples are
the shape of the protoconch, features of the shoulder, and
the presence or absence of black pigment on portions of
the animal. Caution is advised, however, in the frequent
cases where the protoconch is either worn or absent, or
where the tissue has been stained or preserved. Also, po-
tentially misleading black coloration may occur in the
digestive gland of individuals of A. canaliculata that have
been feeding on a blackish food source. This coloration,
however, is restricted to the digestive gland and does not
affect the areas of the gizzard, pallial caecum, or Han-
cock’s organs.

ACKNOWLEDGMENTS

A large portion of the time required to conduct this work
was generously allowed by Dr. Robert W. Virnstein and
Mr. John E. Miller, both of Harbor Branch Foundation,
Inc. (HBF), and by Dr. Robert H. Gore of Smithsonian
Institution’s Marine Station at Link Port (SIFP). Their
comments concerning the study are also very much ap-
preciated. Ms. Patricia Linley (HBF), Drs. Kerry B. Clark
(Florida Institute of Technology), David R. Franz
(Brooklyn College), Richard Houbrick (USNM), Ter-
rence M. Gosliner (USNM), Eileen Jokinen (University
of Connecticut), Eveline du Bois-Reymond Marcus (Uni-
versity of Sao Paulo, Brazil), R. Tucker Abbott (Ameri-
can Malacologists, Inc.), and David R. Lindberg (Mu-
seum of Paleontology, University of California, Berkeley)
suggested pertinent references and/or reviewed various
drafts of the manuscript. We thank Julie Piraino (SIFP)
for instructions concerning SEM preparation and for op-
eration of the scanning electron microscope, Kristen
Metzger (HBF), Carol Browder (HBF), Dr. Joseph
Rosewater (USNM) and Diane Bohmhauer (USNM) for
providing literature, Tom Smoyer (HBF) for photogra-
phy, M. G. Harasewych for electrophoresis, and the HBF
Division of Marine Science secretarial staff for typing
various drafts of the manuscript. We also gratefully ac-
knowledge the instruction and time donated by John E.
Miller (IBF), whose experience and methodology in
handling minute echinoderm ossicles was of great value
in the manipulation of small radulae. Katie Nall (HBF),
Chris Donohoe (HBF), and Kenneth Severin (SIFP) as-
sisted with computer analyses.

The Veliger, Vol) 273 Now

The following generously loaned specimens under their
care for the various aspects of this study: Dr. Joseph Rose-
water (USNM), Dr. John Taylor and Ms. Kathie Way
(BM(NH)), Dr. Robert Robertson and Ms. Mary A.
Garback (ANSP), Dr. Kenneth J. Boss, Dr. Ruth D.
Turner, and Ms. Carey Westermann (MCZ), Dr. Albert
E. Sanders (ChM), Dr. Thomas Pulley and Ms. Con-
stance Boone (HMNS), Prof. Dr. Rudolf Kilias (Mu-
seum fiir Naturkunde der Humboldt-Universitat zu Ber-
lin), Dr. Robert Van Dolah (South Carolina Marine
Resources Research Inst., Charleston, SC), Dr. Lyle D.
Campbell (Univ. of South Carolina at Spartanburg), Hugh
J. Porter (UNC-IMS), Dr. David R. Franz (Brooklyn
College, NY), Dr. E. de C. Rios (MORG), Dr. Juan L.
Botto (MACN), and Raymond Grizzle (Water Resources
Department, Brevard Co., FL). Mr. & Mrs. William O.
Boger of Merritt Island, Florida, discovered the fossil
specimens of Acteocina atrata and brought them to our
attention. Collecting assistance was also provided by K.
D. Cairns, M. A. Capone, K. D. Clark, C. Curran, and
B. Fry. A special thanks goes to Mr. and Mrs. Richard
E. Petit for their assistance, advice, and hospitality.

This is Contribution Number 296 of the Harbor Branch
Foundation, Inc., and Contribution Number 74 of Smith-
sonian Institution’s Marine Station at Link Port.

LITERATURE CITED

ABBOTT, R. T. 1974. American seashells. 2nd ed. Van Nos-
trand Reinhold: New York. 663 pp., 24 pls.

ApAMS, A. 1850. Monograph of the family Bullidae. Pp. 553-
608, pls. 120-125. In: G. B. Sowerby (ed.), Thesaurus con-
chyliorum, vol. II. London.

ADAMS, H. & A. ADAMS. 1854. The genera of Recent Mol-
lusca; arranged according to their organization, vol. II. John
van Voorst: London. 661 pp.

BaiRD, W. 1863. Descriptions of some new species of shells,
collected at Vancouver Island and in British Columbia by
J. K. Lord, Esq., naturalist to the British North-American
Boundary Commission, in the years 1858-1862. Proc. Zool.
Soc. Lond. 1863(Feb. 10):66-70.

BeRTSCH, H. 1976. Intraspecific and ontogenetic radular vari-
ation in opisthobranch systematics (Mollusca: Gastropoda).
Syst. Zool. 25(2):117-122.

BerTScH, H. 1977. The Chromodoridinae nudibranchs from
the Pacific coast of America. Part I. Investigative methods
and supra-specific taxonomy. Veliger 20(2):107-118.

Bonar, D. B. 1978. Morphogenesis at metamorphosis in opis-
thobranch molluscs. Pp. 177-196. In: F. S. Chia & M. E.
Rice (eds.), Settlement and metamorphosis of marine inver-
tebrate larvae. Elsevier: North Holland.

Brown, T. 1827. Illustrations of the conchology of Great Brit-
ain and Ireland. Lizars: Edinburgh. 5 pp., 52 pls.

Brown, T. 1844. Illustrations of the Recent conchology of
Great Britain and Ireland, with description and localities of
all the species, marine, land, and fresh water. 2nd ed. Smith,
Elder, & Co.: London. 144 pp., 59 pls.

CAMPBELL, L. D., S. CAMPBELL, D. COLQUHOUN, J. ERNISSEE
& W. ABBOTT. 1975. Plio-Pleistocene faunas of the cen-
tral Carolina coastal plain. Geologic Notes 19(3):50-124.

P. S. Mikkelsen & P. M. Mikkelsen, 1984

CERNOHORSKY, W. O. 1978. The taxonomy of some Indo-
Pacific Mollusca. Rec. Auckland Inst. Mus. 15:67-86.
ConraD, T. A. 1846. Descriptions of new species of fossil and
Recent shells and corals. Proc. Acad. Natur. Sci. Phila. 3:

19-27, 1 pl.

ConraD, T. A. 1847. Observations on the Eocene formation,
and descriptions of one hundred and five new fossils of that
period, from the vicinity of Vicksburg, Mississippi, with an
appendix. Proc. Acad. Natur. Sci. Phila. 3:280-299.

ConraD, T. A. 1868. Descriptions of new genera and species
of Miocene shells, with notes on other fossil and Recent
species. Amer. J. Conchol. 3(4):257-270, pls. 19-24.

Da.LL, W. H. 1889. Reports on the results of dredging, under
the supervision of Alexander Agassiz, in the Gulf of Mexico
(1877-78) and in the Caribbean Sea (1879-80), by the U.S.
coast survey steamer “Blake,” Lieut.-Commander C. D.
Sigsbee, U.S.N., and commander J. R. Bartlett, U.S.N.,
commanding. XXIX. Report on the Mollusca. Part 2. Gas-
tropoda and Scaphopoda. Bull. Mus. Comp. Zool. 18:1-
492, pls. 10-40.

Da.LL, W. H. 1890. Contributions to the Tertiary fauna of
Florida, with special reference to the Miocene Silex-beds of
Tampa and the Pliocene beds of the Caloosahatchie River.
Part I. Pulmonate, opisthobranchiate, and orthodont gastro-
pods. Trans. Wagner Free Inst. Sci. Phila. 3(1):1-200, pls.
1-12.

Dat, W. H. 1908. Reports on the dredging operations off the
west coast of Central America to the Galapagos, to the west
coast of Mexico, and in the Gulf of California, in charge of
Alexander Agassiz, carried on by the U.S. Fish Commission
Steamer “Albatross,” during 1891, Lieut. Commander Z.
L. Tanner, U.S.N., Commanding. XXVII. Reports on the
scientific results of the expedition to the eastern tropical
Pacific, in charge of Alexander Agassiz, by the U.S. Fish
Commission Steamer ‘Albatross,’ from October, 1904, to
March, 1905, Lieut. Commander L. M. Garrett, U.S.N.,
Commanding. XIV. The Mollusca and the Brachiopoda.
Bull. Mus. Comp. Zool. 43(6):205-487, pls. 1-22.

DALL, W. H. 1922. Note on Acteocina. Nautilus 35(3):96.

Dance, S. P. 1966. Shell collecting: an illustrated history.
Faber & Faber: London. 344 pp., 35 pls.

DE GREGORIO, A. 1890. Monographie de la faune Eocénique
de l’Alabama et surtout de celle de Claiborne de l’étage
Parisien (horizon a Venericardia planicosta Lamk.). Annales
de Géologie et de Paléontologie, livr. 7-8. Librairie Inter-
nationale L. Pedone Lauriel, Palerme. 316 pp., 46 pls.

D’OrBIGNY, A. 1841. Mollusques, vol. 1. Jn: R. Sagra, Histoire
physique, politique, et naturelle de |’Ile de Cuba. Paris.

D’ORBIGNY, A. 1842. Mollusques, atlas. Jn: R. Sagra. Histoire
physique, politique, et naturelle de l’Ile de Cuba. Paris.

Emmons, E. 1858. Report of the North Carolina Geological
Survey. Agriculture of the eastern counties; together with
descriptions of the fossils of the Marl Beds. Bull. Amer.
Paleontol. 56(249):230 pp.

FRANZ, D.R. 1971a. Possible variability in larval development
between populations of the cephalaspid opisthobranch Ac-
teocina canaliculata (Say). (abstract). Amer. Malac. Union
Ann. Repts. for 1970:68-69.

Franz, D. R. 1971b. Development and metamorphosis of the
gastropod Acteocina canaliculata (Say). Trans. Amer. Mi-
croscop. Soc. 90(2):174-182.

Gass, W. M. 1873. Description of some new genera of Mol-
lusca. Proc. Acad. Natur. Sci. Phila. 1872:270-274.

GARDNER, J. 1948. Mollusca from the Miocene and Lower
Pliocene of Virginia and North Carolina. Part 2. Scapho-

Page 191

poda and Gastropoda. U.S. Geol. Surv. Prof. Pap. 199-B:
179-310, pls. 24-38.

GOSLINER, T. M. 1979. A review of the systematics of Cylich-
nella Gabb (Opisthobranchia: Scaphandridae). Nautilus
93(2-3):85-92.

GosLINER, T. M. 1980. Systematics and phylogeny of the
Aglajidae (Opisthobranchia: Mollusca). Zool. J. Linn. Soc.
68(4):325-360.

GouLp, A. A. 1840. [Descriptions of thirteen new species of
shells.] Silliman’s American Journal of Science, ser. 1, 38:
196.

Gray, J. E. 1847. A list of genera of Recent Mollusca, their
synonyma and types. Proc. Zool. Soc. Lond. part 15(1847):
129-219.

Guppy, R. J. L. 1867. Notes on West Indian geology, with
remarks on the existence of an Atlantis in the Early Tertiary
Period; and descriptions of some new fossils, from the Car-
ibean [sic] Miocene. Geol. Mag. 4:496-501, 6 text figs.

Hurst, A. 1967. The egg masses and veligers of thirty north-
east Pacific opisthobranchs. Veliger 9(3):255-288, pls. 26-
38.

KIENER, L.-C. 1834. Genre Tornatelle. In: Spécies général et
iconographie des coquilles vivantes comprenant la collection
du Muséum d’Histoire naturelle de Paris.... J.-B. Bailliére
et Fils: Paris. 6 pp., 1 pl.

KNIGHT, J. B. 1952. Primitive fossil gastropods and their bear-
ing on gastropod classification. Smithsonian Misc. Coll.
117(13):1-56, pls. 1-2.

Lea, I. 1833. Contributions to geology. Carey, Lea and Blan-
chard: Philadelphia. 227 pp., 6 pls.

LINDBERG, D. R. 1977. Artifacts incurred by the treatment of
acmaeid radulae with alkalies. Veliger 14(4):453-454.
Marcus, E. 1956. Notes on Opisthobranchia. Bol. Inst.

Oceanogr. Sao Paulo 7(1-2):31-79.

Marcus, E. 1977. On the genus Jornatina and related forms.
J. Moll. Stud., Suppl. 2:1-35.

Mazyck, W.G. 1913. Catalog of Mollusca of South Carolina.
Contr. Charleston Mus. 2:1-39.

MEYER, O. 1887. On invertebrates from the Eocene of Missis-
sippi and Alabama. Proc. Acad. Natur. Sci. Phila. 1887(pt.
1):51-56, pl. 3.

MIKKELSEN, P. M. & P. S. MIKKELSEN. 1983. Two types of
larval development in the opisthobranch Cylichnella canali-
culata (Say, 1826). (abstract). Bull. Amer. Malac. Union 1:
91.

MIKKELSEN, P. S. & P. M. MIKKELSEN. 1982. Shell and rad-
ular variability in Utriculastra canaliculata (Say, 1826) (Gas-
tropoda: Scaphandridae). (abstract). Bull. Amer. Malac.
Union for 1981:38.

MINICcHEV, Y.S. 1966. [Morphological peculiarities of abyssal
Cephalaspidea (Gastropoda, Opisthobranchia)]. (In Rus-
sian with English abstract). Zoologischiskii Zhurnal 45(4):
409-517, 3 text figs.

MontTacu, G. 1803. Testacea Britannica, or natural history
of British shells, marine, land, and fresh-water, including
the most minute: systematically arranged and embellished
with figures. J. White: London. 1:291 pp. II:plates.

Oxsson, A. A. 1964. Neogene mollusks from northwestern
Ecuador. Paleontological Research Institution: Ithaca, NY.
256 pp., 38 pls.

Ousson, A. A. & A. HARBISON. 1953. Pliocene Mollusca of
southern Florida, with special reference to those from north
Saint Petersburg. Monogr. Acad. Natur. Sci. Phila. No. 8:
457 pp., 65 pls.

Ousson, A. A. & T. L. McGinty. 1958. Recent marine mol-

Page 192

The Veliger, Vol. 27, No. 2

lusks from the Caribbean coast of Panama with the descrip-
tion of some new genera and species. Bull. Amer. Paleontol.
39(177):1-58, pls. 1-5.

PFEIFFER, L. 1840. Uebersicht der im Januar, Februar und
Marz 1839 auf Cuba gesammelten Mollusken. Archiv fiir
Naturgeschichte 6(1):250.

Pirssry, H. A. 1921. Revision of W. M. Gabb’s Tertiary
Mollusca of Santo Domingo. Proc. Acad. Natur. Sci. Phila.
73(pt. 2):305-435, pls. 16-47.

RicHarps, H. G. 1947. Invertebrate fossils from deep wells
along the Atlantic coastal plain. J. Paleontol. 21(1):23-37,
pls. 11-15.

RicHarps, H. G. 1968. Catalogue of invertebrate fossil types
at the Academy of Natural Sciences of Philadelphia. Acad.
Natur. Sci. Phila., Spec. Publ. 8:222 pp.

RupMAN, W. B. 1978. A new species and genus of the Agla-
jidae and the evolution of the philinacean opisthobranch
molluscs. Zool. J. Linn. Soc. 62:89-107.

Sars, G. O. 1878. Bidrag til kundskaben om Norges Arktiske
fauna. I. Mollusca regionis Arcticae Norvegiae. Christiania.
466 pp., 52 pls.

Say, T. 1826. Descriptions of marine shells recently discovered
on the coast of the United States. J. Acad. Natur. Sci. Phila.
5:207-221.

Say, T. 1832. American conchology, or descriptions of the
shells of North America, Part IV. New Harmony, Indiana.

SMITH, S. T. 1967a. The development of Retusa obtusa (Mon-
tagu) (Gastropoda, Opisthobranchia). Can. J. Zool. 45:737-
764.

SMITH, S. T. 1967b. The ecology and life history of Retusa
obtusa (Montagu) (Gastropoda, Opisthobranchia). Can. J.
Zool. 45:397-405.

SOLEM, A. 1972. Malacological applications of scanning elec-
tron microscopy. II. Radular structure and functioning. Ve-
liger 14(4):327-336, 6 pls.

SwITZER-DuNLAP, M. & M. HapFIELD. 1981. Laboratory
culture of Aplysia. Pp. 199-216. In: Committee on Marine
Invertebrates, National Research Council (ed.), Laboratory
animal management; marine invertebrates. National Acad-
emy Press: Washington, DC.

THIELE, J. 1925. Gastropoda der Deutschen Tiefsee-Expedi-
tion. Part 2. Wiss. Ergebnisse der Deutschen Tiefsee-Ex-
pedition 17:37-382.

TuRNER, R. D. 1960. Mounting minute radulae. Nautilus
73(4):135-137.

WELLS, H. W. & M. J. WELLS. 1962. The distinction between
Acteocina candei and Retusa canaliculata. Nautilus 75(3):87-
93.

WoopRING, W. P. 1928. Contributions to the geology and
paleontology of the West Indies. Miocene mollusks from
Bowden, Jamaica. Part II. Gastropods and discussion of
results. Carnegie Inst. Wash. 564 pp., 40 pls.

WoopbRING, W. P. 1970. Geology and paleontology of the Ca-
nal Zone and adjoining parts of Panama. Description of
Tertiary mollusks (Gastropoda: Eulimidae, Marginellidae
to Helminthoglyptidae). U.S. Geol. Surv. Prof. Paper 306-
D:299-452, pls. 48-66.

THE VELIGER
© CMS, Inc., 1984

The Veliger 27(2):193-199 (October 5, 1984)

Pseudo-operculate Pulmonate Land
Snails from New Caledonia
by

ALAN SOLEM

Department of Zoology, Field Museum of Natural History,
Roosevelt Road & Lake Shore Drive, Chicago, Illinois 60605

SIMON TILLIER

Laboratoire de Biologie des Invertebrates Marins et Malacologie,
55, Rue de Buffon, 75005 Paris, France

AND

PETER MORDAN

Department of Zoology, British Museum (Natural History),
Cromwell Road, London SW7 5BD, United Kingdom

Two genera of New Caledonian land snails, Pararhytida Ancey, 1882 and Rhytidopsis

Ancey, 1882, have a thick oval mass of densely compacted connective tissue formed on the dorsal side
of their tail. This functions as an operculum to block the shell aperture when the animal retracts, and
is named the pseudo-operculum. They are the only pulmonate land snails to have evolved a functional
equivalent of the prosobranch operculum. Pararhytida inhabits dense leaf litter on the ground, while
Rhytidopsis is an arboreal genus. Shells of both genera are very large compared with other charopid
genera. The pseudo-operculum may have evolved under predation pressure from the large New Cal-
edonian carnivorous land snails belonging to the genera Ouagapia Crosse, 1894 and Ptychorhytida
Mollendorff, 1903 (family Rhytididae), and may have an exaptive value for size increase in leaf litter
and for colonizing arboreal habitats in New Caledonian rain forests.

INTRODUCTION

THE PRESENCE of a horny or calcareous disk on the dorsal
surface of the tail is one of the most obvious characters
separating the prosobranch gastropods from the pulmo-
nates. Among the latter, larval stages of the marine On-
chidiidae (FRETTER, 1943), Otinidae, Ellobiidae, and
Amphibolidae (HUBENDICK, 1978) retain the operculum,
but it persists in adults of only two genera of Amphibol-
idae, Salinator Hedley, 1900 and Amphibola Schumacher,
1817. No land or fresh-water pulmonates have an oper-
culum.

The fresh-water and terrestrial prosobranchs use the
operculum both as a means of retarding water loss and as
defense against predators. The effectiveness of the oper-

culum as a seal in excluding environmental dangers is
shown by the example of the fresh-water prosobranch
Pomacea cumingu (King & Broderip, 1831) from Panama,
whose relatively thin and horny operculum permitted sur-
vival through a more than one hour immersion in a stan-
dard alcohol-formalin amphibian killing solution
(NETTING, 1936). Many terrestrial prosobranch genera
independently have evolved accessory breathing tubes in
the shell itself to permit gas exchange during diapause
(REES, 1964:58-65, pls. 3-5), as their calcareous opercula
provide extremely tight-fitting seals.

In most terrestrial pulmonates, defense against preda-
tors and retardation of water loss are functionally sepa-
rated. Pulmonates secrete a sheet of mucus across the ap-

Page 194

erture which may retard water loss during diapause. This
sheet may or may not be heavily calcified, and may be
with or without a special breathing pore. Various struc-
tural and behavioral characteristics are used in defense
against predation. Among the structural modifications may
be development of a thick shell to defeat gnawing, provi-
sion of internal apertural barriers to prevent ingress by
small arthropods (SOLEM, 1972), or sealing of the shell to
a rock or piece of wood with mucoid cement so that re-
moval requires considerable force. Nearly all members of
the family Clausiliidae make use of a special structure,
the clausilium, in addition to large apertural barriers, to
close the aperture. Evolution of this structure from a col-
umellar barrier that became detached has been postulated
by NoRDSIECK (1982). Shell color patterns may be effec-
tive in confusing potential predators (CAIN, in press). Be-
havioral adaptations include habitat shifts such as nightly
tree climbing to avoid a nocturnal ground foraging pred-
ator, or day-time retreat into narrow crevices to avoid a
diurnal predator. A few pulmonate species are known to
secrete mucus-containing irritating chemicals, for example
Liguus (EISNER & WILSON, 1970). The endemic ant
Camptonotus was found to be repelled by Liguus mucus,
but the introduced fire ant Solenopsis geminata (Fabricius)
is successful in feeding on Liguus (TUSKES, 1981). Other
species, such as Sultana sultana (Dillwyn, 1817), have a
very sticky mucus that will engulf small predators (TIL-
LIER, 1980:71). Veronicellid slugs in Samoa are a major
problem to chicken owners, as their mucus can kill the
fowls (SOLEM, 1971).

Only one other land pulmonate has been reported pre-
viously to have a mechanical device for shell closure, the
enigmatic Thyrophorella thomensis Greeff, 1882 from Sao
Thome. This species is described as having a loose flap of
the shell, connected only to the upper palatal margin of
the shell lip, that can fall down over the aperture and then
later be pushed up by the extending snail (GREEFF, 1882,
1884; GIRARD, 1893, 1895). The flap itself is not attached
to the snail’s body, and thus is not homologous to the
operculum, nor can it function as a tight seal. Only frag-
mentary data have been published on the anatomy of 7hy-
rophorella (above references), and whether it actually
should be a monotypic family, as customarily listed, is
uncertain. We have been unable to find later references
to collections of this species, and the materials taken by
Newton and reported on by GIRARD (1893, 1895) prob-
ably were destroyed in the fire at the Museu Bogage in
Lisbon several years ago. Pending collection of new ma-
terial and detailed anatomical study, this species will re-
main a puzzle.

The discovery that two genera of New Caledonian pul-
monate land snails have a “‘pseudo-operculum” developed
on the dorsal side of their tail is of general interest. When
the snail is retracted into the aperture (Figure 1), this
structure effectively blocks the opening and thus functions
in an analagous way to a prosobranch operculum.

The Veliger, Vol. 27, No. 2

OCCURRENCE oF THE
PSEUDO-OPERCULUM

The described land snail fauna of New Caledonia num-
bers only about 110 species (FRANC, 1957; SOLEM, 1961),
but recent collections by P. Bouchet, P. Mordan, L. Price,
A. Solem, A. Tillier, S. Tillier, and assistants indicate an
actual diversity level of 300-400 species (Tillier, in TiL-
LIER & CLARKE, 1983). The dominant group in terms of
species numbers is the Charopidae (sensu SOLEM, 1983;
listed as Endodontidae by FRANC, 1957, and SOLEM, 1961).
More than half of the described New Caledonian land
snail species belong to the Charopidae. New discoveries
probably will increase this proportion.

Two charopid genera, Rhytidopsis Ancey, 1882 and
Pararhytida Ancey, 1882, currently being revised (Tillier
& Mordan, in preparation), share development of the
pseudo-operculum and unique structures in the terminal
female genitalia. Preserved specimens are available now
for most other New Caledonian charopids, but no trace
of a pseudo-operculum has been seen by the authors in
any other taxa. Once seen and recognized, it will not be
forgotten, although two malacologists who reported on the
anatomy of Pararhytida dictyodes (Pfeiffer, 1847) surpris-
ingly did not mention it (FISCHER, 1875; STARMUHLNER,
1970:302-305).

Rhytidopsis chelonites (Crosse, 1868) is the only de-
scribed species correctly assigned to Rhytidopsis (Tillier,
unpublished results). Rhytidopsis ranges from Mt. Hum-
boldt, somewhat north of Nouméa, to the southern tip of
New Caledonia. In recent years, living specimens have
been collected in rain forests at 150 to 1350 meters ele-
vation, always from tree trunks or from the underside of
leaves. The shell is relatively small (diameter 6-8 mm),
flammulated to dotted in color pattern, and without major
sculpture; the umbilicus is minute, and the shell slightly
carinated at the periphery. Other taxa traditionally as-
signed to Rhytidopsis on the basis of general conchological
similarity (see FRANC, 1957; SOLEM, 1961) also are ar-
boreal, but have very narrow and elongated tails with a
prominent caudal horn, often strongly sculptured shells,
and no trace of a pseudo-operculum. Eventually they will
be transferred into other genera.

Pararhytida, as revised by Tillier & Mordan (in prep-
aration), excludes the taxa Micromphalia Ancey, 1882 and
Plesiopsis Ancey, 1888. It includes six species, several of
them new. Pararhytida ranges throughout the main island
of New Caledonia and the Belep Islands, but is absent
from the younger Loyalty Islands. Old records from the
Isle of Pines have not been confirmed in recent decades.
Pararhytida is found in most forest patches, excluding the
high altitude rain forests and the very dry lowland forests.
The largest species, Pararhytida dictyodes (Pfeiffer, 1847),
ranges over the entire island and is quite variable. It is
possible that it includes a complex of cryptic species. The
remaining taxa show restricted ranges that correlate with

A. Solem et al., 1984

Page 195

be eda

re |

Figure 1

Retracted specimen of Pararhytida dictyodes showing functional position of the pseudo-operculum (Photograph by

A. Solem).

particular rainfall regimes (Tillier & Mordan, in prepa-
ration). All species of Pararhytida are litter dwellers, and
they are especially common inside the sheath portions of
fallen palm fronds. They have not been taken under logs
or in the rotting wood habitats utilized by other New
Caledonian charopids. In most species the shell is sharply
carinated and the umbilicus is wide. Adult shell diameter
within Pararhytida is from 14 to almost 37 mm.

Thus, Rhytidopsis and Pararhytida differ in shell shape,
size, ecology, and geographic range. Their monophyly is
suggested by their unique pseudo-opercula and structures
in the terminal genitalia.

STRUCTURE anp FUNCTIONING
OF THE PSEUDO-OPERCULUM

In both Rhytidopsis (Figure 2) and Pararhytida (Figure 3)
the tail is relatively short and broad. The dorsal portion
is clearly flattened and expanded into an elongately oval
disk that extends from the visceral stalk to the tip of the
tail. Its posterior margin can be rounded or narrowly tri-

angular, and varies individually. This novel structure is
here named the pseudo-operculum.

The pseudo-opercula of two species of Pararhytida, P.
dictyodes and P. mouensis (Crosse, 1868), have been ex-
amined histologically in longitudinal and transverse sec-
tion, and are essentially similar in structure. The pseudo-
operculum is composed of a thick pad of irregularly in-
terwoven fibers underlying a single layer of epidermis.
Staining with Masson’s trichrome shows these fibers to be
composed of collagen. The pad extends from just above
the supra-pedal grooves to the top of the tail. It is ex-
tremely difficult to cut and almost impossible to tear. While
the covering epithelium can be ruptured very easily, and
was lost from much of the histological material studied
here, the fibrous layer resists disturbance.

In section the pseudo-operculum may be broadly divid-
ed into two regions, which appear more sharply differ-
entiated in Pararhytida mouensis than in P. dictyodes. Im-
mediately below the epidermis lies a dense mass of collagen
fibers with only a very few weak muscles. Beneath this is
a rather more deeply staining layer of collagen, containing

Page 196

The Veliger, Viol 275 Now

cP

Gre AO Vie 1)
&
Whe LS Ea

Explanation of Figures 2 to 4

Figure 2. Preserved specimen of Rhytidopsis chelonites from Col
de la Pirogue, Mont Mou, New Caledonia showing pseudo-
operculum. FMNH 144272. Collected January 23, 1962.

Figure 3. Preserved specimen of Pararhytida dictyodes from Col

numerous muscle fibers, which, in the main portion of the
pseudo-operculum, have a predominately dorsoventral
orientation. These muscles extend well beyond the pseu-
do-opercular pad into the tail proper, where the fibers run
mainly in the longitudinal plane (Figure 5). It is clear
from the preparations stained with Alcian blue that, un-
like the usual exposed epidermis of pulmonates, the sur-
face of the pseudo-operculum is devoid of mucocytes and
other secretory cells.

de la Pirogue, Mont Mou, New Caledonia showing pseudo-
operculum. FMNH 135440. Collected January 25, 1962.

Figure 4. Cross-section through tail of Rhytidopsis chelonites
(FMNH 144272) showing pseudo-operculum (CP) and pedal
grooves (FS).

When the animal retracts into the shell, the dorsal part
of the tail angles across the plane of the aperture, with its
posterior tip on the outer palatal wall and the anterior
section against the parietal margin (Figure 1). The pseu-
do-operculum thus effectively fills the shell aperture. This
functioning implies that the pattern of retraction of Para-
rhytida and Rhytidopsis into their shells is different from
the pattern observed in most terrestrial pulmonate snails.
In the latter, the tail itself is retracted until its posterior

A. Solem et al., 1984

Figure 5

Transverse section through tail of Pararhytida dictyodes from Mt.
Canala, New Caledonia, 900-1050 m, New Caledonia. Collect-
ed January 21, 1979. Magnification 31.5.

tip lies above the pallial border. Space for this is provided
by the lateral outward compaction of the lung cavity. Con-
sequently only the mantle border is exposed in the plane
of the aperture, and can thus secrete an epiphragm to
separate the snail from the outside world. In both Para-
rhytida and Rhytidopsis, the tail remains distal to the pal-
lial border, which may be related to the fact that the
pseudo-operculum functionally replaces the epiphragm.
Charopids and endodontids both secrete thin mucus sheets,
and even taxa from drier Australian areas are not known
to have calcareous thickening of the epiphragm (Solem,
personal observations).

Although the exposed epithelial layer of the pseudo-
operculum would be subject to evaporative water loss, pre-
sumably overall permeability would be reduced by the
fibrous layer underneath. Instead of water passing freely
from the entire tail surface to the exposed areas, it would
have to flow around the edges of the pad, and, thus, less
water would reach the evaporative surface itself. Con-
traction of the dorsoventral muscles in the pseudo-oper-
culum could serve to expand the pad laterally and thus
provide a better fit in the aperture. The exposed epithelial
surface probably functions in respiration, since air flow to

Page 197

the lung cavity would be severely impeded by the pseudo-
operculum. It is also possible that the epidermis itself
could actively reduce evaporative water loss, as has been
shown in some European helicids (MACHIN, 1974; NEw-
ELL & APPLETON, 1979).

The extent to which the pseudo-operculum gives actual
protection against predation cannot be evaluated at pres-
ent, but clearly the presence of a thick collagen fiber layer
is potentially of great protective value. Rhytidids have
been observed feeding on Pararhytida (Tillier, personal
observations), but no analysis of rhytidid diets in New
Caledonia has been attempted.

EVOLUTION oF THE PSEUDO-OPERCULUM

Geologically, New Caledonia is a fragment of the eastern
border of Gondwana, which split off northeastern Aus-
tralia during the Triassic, approximately 230 million years
ago. It was possibly covered subsequently by two marine
transgressions, but has been constantly exposed land since
at least the Oligocene, or about 30 million years (PARIS
& LILLE, 1977). As a result of this long isolation and
existence as elevated land, the whole primary land snail
fauna of New Caledonia is endemic at the specific level
and many genera also are limited to New Caledonia.

The numerically dominant land snails of the family
Charopidae show specializations in comparison with
charopids elsewhere. The arboreal element is much better
represented, and by far the largest species of Charopidae
are found in New Caledonia.

A survey of body types in New Caledonian charopid
land snails suggests a basic form dichotomy into (1) taxa
with narrow, elongated tails that end in a prominent mu-
cus pore and often a caudal horn, such as is common in
the New Zealand otoconchine charopid genera (CLIMO,
1969:figs. 5A-F, 1971:figs. 1A—D) and (2) taxa with fair-
ly short, often truncated tails, such as are found in typical
Pacific Basin charopids (SOLEM, 1983:26, fig. 9a). The
former tend to be arboreal in habits, the latter tend to be
ground dwellers. Taxa of the Rhytidopsis-Pararhytida clade
belong to the second morphological group, and are the
only identified clade to be both arboreal and terrestrial.

The entire New Caledonian radiation of charopids is
marked by a tendency towards large size, and Pararhytida
includes the largest of all known charopids. Carnivorous
land snails in New Caledonia reach moderately large size,
1.e., the 12-25 mm in diameter Ptychorhytida MOllendorff,
1903 and the 30-35 mm Ouagapia raynali (Gassies, 1863).
These rhytidids are ground dwellers, and the large, litter-
dwelling charopids would be logical prey for them. We
do not know whether they feed exclusively on Pararhytida,
but, as mentioned above, Ouagapia has been observed to
feed on Pararhytida. The latter’s habit of resting in the
curled sheath portion of fallen palm fronds, not tightly
sealed to the sheath surface, combined with the relatively
large aperture of its shell, would leave the animals easy

Page 198

victims for predatory ground snails. Any thickening of the
exposed portion of the retracted animal that might dis-
courage a feeding attempt would have selective value. In-
tensification of this trend would lead to the evolution of
the pseudo-operculum. Because Pararhytida tends to be
absent from the drier forests, we hypothesize that the
pseudo-operculum functions primarily against predation.

Retardation of water loss would be a secondary benefit
that might permit some members of the clade to utilize
arboreal hatitats, which are subject to greater humidity
fluctuations, without any more morphological modifica-
tion of the foot and lung cavity. The primacy of predation
as a selective pressure in the evolution of the pseudo-
operculum may find some confirmation from observations
on the only terrestrial snails known to us that exhibit a
pattern of animal retraction that is intermediate between
the usual pattern and that found in the pseudo-operculate
taxa. The large, African ground dwelling achatinids, for
example Achatina fulica (Bowditch, 1822), when dis-
turbed, do not retract their tail above the pallial border,
but twist the tail so that its left side blocks the aperture,
with the tip of the tail at the parieto-palatal margin (Bind-
er, personal observation; also present authors). Subse-
quent full retraction and epiphragm building occurs in
achatinids, so that this is not fully comparable, but this
parallel behavior in an unrelated group is of interest. This
use of the tail as a temporary and possibly protective block
in achatinids suggests that possibly the primary adaptive
value of the pseudo-operculum was protection.

A similar behavioral pattern involving exposure of the
left side of the body after retraction into the shell has been
noted in the fresh-water basommatophoran genus Lym-
naea (STOREY, 1972, 1983). However, this pattern was
observed only as a response to drought conditions, whereas
simple withdrawal during short periods of inactivity left
the sole of the foot exposed in the aperture. Storey was
able to demonstrate a marked reduction in the rate of
water loss from the exposed body wall when compared
with the foot surface in retracted snails.

Rhytidopsis (diameter 6-8 mm) is much smaller than
Pararhytida (diameter 14-37 mm). We assume that both
are descended from an even smaller ancestor that was
terrestrial in habitat. Evolution of the pseudo-operculum
in the ancestor would have preceded both the arboreal
shift by Rhytidopsis and the large size by Pararhytida. We
view this evolution as a possible release mechanism for
both changes.

Large size permits Pararhytida to fill the size gap for a
herbivorous land snail between the typical small (2-4 mm)
charopids and the huge New Caledonian Placostylus (some
over 100 mm) of the family Bulimulidae. In other faunas,
this size range is filled normally by members of the Ca-
maenidae-Bradybaenidae- Helminthoglyptidae - Helicidae
lineages. These taxa have much more complex kidney and

ureteric structures (BOUILLON, 1960:fig. A) than are found”

in the Charopidae (Tillier, unpublished data). A normal

The Veliger, Vol: 27,53NoaZ

charopid, with its simple kidney and ureter, might not
find wet enough niches in New Caledonia to reach large
size. With the pseudo-operculum, and in the absence of
competitive snail taxa, evolution of large size and exploi-
tation of this size range became possible.

If these views are correct, it is clear that the pseudo-
operculum that evolved under predator pressure has a
selective value for size increase. In this sense, the pseudo-
operculum is clearly an exaptation in the sense of GOULD
& VRBA (1982:4): “features that now enhance fitness but
were not built by natural selection for their current role.”

The above speculations go well beyond available data,
but it will be many years before systematic revisions of
the New Caledonian land snail taxa are completed, per-
mitting more accurate analysis of the ecological roles played
by the constituent families. Adequate comparative data for
the Australian, Melanesian, and New Zealand faunas also
are lacking. But perhaps presentation of these ideas will
help stimulate the work needed to test them.

ACKNOWLEDGMENTS

We are indebted to the many people who have assisted in
New Caledonian field work and subsequent curation of
the collections. Illustrations are by Patricia Rill Smiley
(Figure 3) and Nelva Bonucchi Richardson (Figures 2,
4). Dorothy Karall, Associate, Division of Invertebrates,
Field Museum of Natural History, mounted and labeled
the illustrations.

LITERATURE CITED

BOUILLON, J. 1960. Ultrastructure des cellules rénales des
Mollusques. I. Gastéropodes Pulmonés terrestres (Helix po-
matia). Ann. Sci. Naturelles, Zoologie, 12eme Série:719-
749.

Cain, A. J. In press. Heads, tails and falling snails. Malaco-
logia.

Cuimo, F. M. 1969. Classification of New Zealand Arionacea
(Mollusca, Pulmonaia). I. The higher classification. Rec.
Dominion Mus., Wellington 6(12):145-158.

Cuimo, F. M. 1971. Classification of New Zealand Arionacea
(Mollusca: Pulmonata). IV. A revision of the subfamily
Otoconchinae Cockerell (Punctidae Morse). Rec. Dominion
Mus., Wellington 7(6):43-49.

EISNER, T. & E. O. WILSON. 1970. Defensive liquid discharge
in Florida tree snails (Liguus fasciatus). Nautilus 84(1):14-
15.

FISCHER, P. 1875. Note sur l’anatomie de lHelix dictyodes,
Pfeiffer. J. de Conchyl. 23(4):273-276.

Franc, A. 1957. Mollusques terrestres et fluviatiles de l’Ar-
chipel Néo-Calédonien. Mém. Mus. Natl. d’Hist. Natur.,
Paris, n.s., Sér. A, Zool. 15:1-200.

FRETTER, V. 1943. Studies in the functional morphology and
embryology of Onchidella celtica (Forbes & Hanley) and
their bearing on its relationships. J. Mar. Biol. Assoc. U.K.
25:685-720.

GirarD, A. A. 1893. Revision de la faune malacologique des
Iles St. Thomé et de Prince. I—Mollusques terrestres et
fluviatiles. J. Sci. Math., Phys. e Natur. (2)3:28-42.

A. Solem et al., 1984

GiIRARD, A. A. 1895. Sur le “7hyrophorella thomensis,”’ Greeff,
Gastéropode terrestre muni d’un faux opercule a charniére.
J. Sci. Math., Phys. e Natur. (2)4:28-32.

GOULD, S. J. & E. VrBa. 1982. Exaptation: a missing term
in the science of form. Paleobiology 8:4-15.

GREEFF, R. 1882. Uber die Landschneckenfauna der Inseln
Sao Thome. Zool. Anz. 5:516-521.

GREEFF, R. 1884. Die Fauna der Guinea-Inseln S. Thomé
und Rolas. Sitzungsb. der Gesellschaft. Naturw. zu Mar-
burg 1884:41-79.

HUBENDICK, B. 1978. Systematics and comparative morphol-
ogy of the Basommatophora. Jn: V. Fretter & J. Peake
(eds.), Pulmonates, 2A:1-47. Academic Press: London.

MAacHIN, J. 1974. Osmotic gradients across snail epidermis:
evidence for a water barrier. Science 183:759-760.

NETTING, M. G. 1936. The viability of a snail in a killing
solution. Nautilus 49(3):104-105.

NEWELL, P. F. & T. C. APPLETON. 1979. Aestivating snails—
the physiology of water regulation in the mantle of the ter-
restrial pulmonate Otala lactea. Malacologia 18:575-581.

NorpbsIEck, H. 1982. Die Evolution der Verschlussapparats
der Schliessmundschnecken (Gastropoda: Clausiliidae). Arch.
Moll. 112:27-43.

Paris, J. P. & R. LILLE. 1977. La Nouvelle Calédonie du
Permien au Miocéne. Bull. de la Recherche Géol. et Mi-
niére (4)1:79-95.

REES, W. J. 1964. A review of breathing devices in land oper-
culate snails. Proc. Malacol. Soc. Lond. 36(2):55-67.

Page 199

SOLEM, A. 1961. New Caledonian land and fresh-water snails.
An annotated check list. Fieldiana: Zoology 41(3):413-501.

SoLeM, A. 1971. Introduction. Mollusks introduced into North
America. Biologist 53(3):89-92.

SOLEM, A. 1972. Microarmature and barriers in the aperture
of land snails. Veliger 15(2):81-87.

SoLEM, A. 1983. Endodontoid land snails from Pacific Islands
(Mollusca: Pulmonata: Sigmurethra). Part II. Families
Punctidae and Charopidae, zoogeography. Field Museum
of Natural History: Chicago. Pp. IX, 336.

STARMUHLNER, F. 1970. Ergebnisse der ésterreichischen Neu-
kaledonien-Expedition 1965. Terrestrische Gastropoda I.
(exkl. Veronicellidae und Athoracophoridae). Ann. Natur-
hist. Mus. Wien 74:289-324.

STOREY, R. 1972. Dormancy in Lymnaea peregra (Miiller)
during periods of dryness. J. Conch., London 27:377-386.

Storey, R. 1983. Dormancy in Lymnaea. J. Conch., London
SEZ Sip

TILLIER, S. 1980. Gastéropodes terrestres et fluviatiles de
Guyana Francaise. Mém. Mus. Natl. d’Hist. Natur., Paris,
n.s., Sér. A, Zool. 115:1-189.

TILLIER, S. & B. CLARKE. 1983. Lutte biologique et destruc-
tion du patrimone génétique: le cas des mollusques gasté-
ropodes pulmonés dans les territoires frangais du Pacifique.
Génet., Sél. Evol. 15(4):93-100.

TuskeEs, P. M. 1981. Population structure and biology of Li-
guus tree snails on Lignumvitae Key, Florida. Nautilus 95(4):
162-169.

THE VELIGER

© CMS, Inc., 1984
The Veliger 27(2):200-218 (October 5, 1984)

Lysinoe (Gastropoda: Pulmonata) and Other Land Snails
from Eocene-Oligocene of ‘Trans-Pecos Texas, and
Their Paleoclimatic Significance
by

BARRY ROTH

Museum of Paleontology, University of California,
Berkeley, California 94720

Abstract. A large helminthoglyptid land snail, Lysinoe breedlovei spec. nov., occurs in the Colmena
Tuff and Chambers Tuff of the Vieja Group, Presidio County, Texas, associated with vertebrates of
the Candelaria and Porvenir local faunas respectively. Lysinoe breedlovei is also present in correlative
strata in the Agua Fria-Buck Hill area of Brewster County, Texas, and in a predominantly marine
sequence in Nuevo Leon, Mexico, associated with a “Vicksburg” molluscan fauna. Associated vertebrate
assemblages from the Texan localities have been assigned to the Uintan and Chadronian North Amer-
ican Land Mammal “Ages.” Radioisotopic dates indicate a time span of about 41-38 Ma before present.
The species is strikingly similar to the Holocene Lysinoe ghiesbreghtu (Nyst) from southern Mexico
and Central America. Climatic and ecological parameters from the range of L. ghiesbreghtu imply that
conditions in this part of Texas during the late Eocene-early Oligocene were moist and temperate and
that the prevailing vegetation was probably an ecological analogue of the seasonal temperate forests of
present-day Chiapas, Mexico. Mean annual rainfall in excess of 123 cm, either with or without a
winter dry season, is indicated. Many plant species of the temperate Mexican forests have similar or
identical counterparts in the southeastern United States. Lysinoe supports the concept of a formerly
continuous forest distribution around the northwestern Gulf of Mexico.

The Candelaria local fauna also includes the helminthoglyptid genus Polymita, now confined to
Oriente Province, Cuba. Other land snails from the Chambers Tuff include two subgenera of Pleuro-
donte (Camaenidae), now confined to Jamaica and the Lesser Antilles, and Xerarionta (Helminthoglyp-
tidae), now living from southern California to southern Baja California. Polymita and Pleurodonte both
now inhabit more tropical forests than Lysinoe. Xerarionta inhabits arid and semiarid zones within the
influence of Pacific fog. By analogy with plant communities, climatic equability may have permitted
the co-occurrence of genera that now show conflicting climatic preferences. The snail assemblages
document a general southward retreat of land mollusk genera through the Tertiary and a developing
allopatry.

with described vertebrate faunas (EVERNDEN et al., 1964;
WILSON et al., 1968; WILSON, 1971, 1978). WILSON et al.
(1968) mentioned in passing the presence of gastropods

INTRODUCTION

THE ViEJA Group of Trans-Pecos Texas and adjacent

Chihuahua, Mexico, consists of about 800 m of interbed-
ded sedimentary, volcanic, and volcaniclastic rocks of
Eocene and Oligocene age. The vertebrate fossils are well
studied, particularly in the so-called Rim Rock Country
lying between the Rio Grande and the Sierra Vieja of
Presidio and Jeff Davis counties. This area is paleonto-
logically important because a number of radiometric dates
have been obtained, in either association or superposition

in rocks of the Vieja Group. PAMPE (1974) described and
illustrated Vieja Group gastropods in his brief report, ap-
plying existing names from the literature of the Rocky
Mountain and Great Plains regions. He evidently be-
lieved them all to be fresh-water forms; my identifications
differ entirely from his. WILSON (1978) included gastro-
pods (mostly unidentified) in his comprehensive Vieja
Group faunal lists.

B. Roth, 1984

The Rim Rock Country is part of an unstable zone
along the western flank of the late Paleozoic Diablo Plat-
form which coincides with the eastern edge of the Meso-
zoic Chihuahua Trough. During late Cretaceous/early
Tertiary (Laramide) diastrophism the thick Cretaceous
sediments of the trough were overthrust against the flank
of the platform; after uplift and erosion of upper Creta-
ceous sedimentary rocks, late Eocene and early Oligocene
eruptions covered most of the area with the volcanic rocks
of the Vieja Group (WILSON et al., 1968). The Vieja Group
consists of nine named formations (DEFoRD, 1958), from
bottom to top the Jeff Conglomerate, Gill Breccia, Col-
mena Tuff, Buckshot Ignimbrite, Chambers Tuff, Bracks
Rhyolite, Capote Mountain Tuff, Brite Ignimbrite (now
considered part of the widespread Mitchell Mesa Rhyo-
lite), and Petan Basalt. The rocks subsequently have been
block faulted, following the general trend of the Basin and
Range faulting of the late Tertiary, and carved by erosion
to create a modern topography of steplike mountain slopes
with extrusive rocks capping prominent ridgecrests.

On the north the Vieja Group interfingers with the
Garren Group in the Van Horn Mountains. A tuff of the
Garren Group in the Indio Mountains in southeastern
Hudspeth County has yielded land snail fossils identified
as the genus Humboldtiana Ihering, 1892 (UNDERWOOD
& WILSON, 1974). Species of Humboldtiana today live in
the mountains bordering the Mexican Plateau and the
mountains of the Big Bend region of Texas (BURCH &
THOMPSON, 1957; BEQUAERT & MILLER, 1973).

Well-preserved land gastropod fossils from the Col-
mena Tuff and Chambers Tuff, collected by John An-
drew Wilson and parties from the University of Texas,
include large snails readily identifiable as belonging to the
genus Lysinoe Adams & Adams, 1855. The only previous
Tertiary fossil record of Lysinoe is a tentative identifica-
tion by GARDNER (1945) in the Eocene of northeastern
Mexico. The species, here described as new, shows re-
markable similarity to the Holocene Lysinoe ghiesbreghtu
(Nyst, 1841) of the Mexican state of Chiapas, Guatemala,
Honduras, and El Salvador, and provides a basis for in-
terpreting the paleoecology and paleoclimate of these parts
of the Vieja Group.

Also present in the Colmena Tuff is a species of Poly-
mita Beck, 1837, a genus confined at the present day to
eastern Cuba and having no other Tertiary fossil record.
The Chambers Tuff has yielded two species here assigned
to Pleurodonte Fischer von Waldheim, 1807, a genus now
confined to Jamaica and the Lesser Antilles, and a species
of Xerarionta, similar to present-day forms from Baja Cal-
ifornia. Samples from the Devil’s Graveyard Formation
in the Agua Fria—Buck Hill area, Brewster County, in-
clude Lysinoe and a low-spired, lenticular form tentatively
assigned to the Camaenidae.

The following abbreviations are used: CAS, Depart-
ment of Invertebrate Zoology, California Academy of Sci-
ences, San Francisco; Ma (Mega-annum), 10° years (be-
fore present); TMM, Vertebrate Paleontology Laboratory,

Page 201

Texas Memorial Museum, University of Texas, Austin;
UCMP, Museum of Paleontology, University of Califor-
nia, Berkeley; USGS, United States Geological Survey;
USNM, Division of Paleobiology, United States National
Museum of Natural History, Smithsonian Institution.

Specimen numbers of TMM consist of a five-digit lo-
cality number, a hyphen, and the specimen number from
that locality, e.g., 40276-16. Detailed descriptions of lo-
calities are on file at the Vertebrate Paleontology Labo-
ratory, Texas Memorial Museum, The University of
Texas at Austin. Devil’s Graveyard Formation and Ban-
dera Mesa Member are manuscript names from STEVENS
et al. (in press) and are reserved by the Geologic Names
Committee, U.S. Geological Survey.

In the species descriptions, whorls are counted by the
method of PILSBRY (1939, fig. B). Shell height is measured
parallel to the axis of coiling; diameter is the greatest
diameter perpendicular to the axis of coiling. Both mea-
surements exclude the expanded lip of mature specimens.

SYSTEMATIC PALEONTOLOGY

Class Gastropoda
Subclass Pulmonata
Order Sigmurethra
Superfamily Helicacea
Family HELMINTHOGLYPTIDAE

Lysinoe Adams & Adams

Aglaja ALBERS, 1850:107. Non Renier, 1807, non Esch-
scholtz, 1825.

Lysinoe ADAMS & ADAMS, 1855:203. MARTENS, 1890-1901:
145-147. Pitsspry, 1895:191-192. Z1LcH, 1960:652.

Odontura FISCHER & CROSSE, 1870:211, 242. Non Rambur,
1838.

Prionodontura H. FISCHER, 1899:304.

Aglaa Albers, auctt., invalid emendation.

Type-species: Helix ghiesbreghtu Nyst, 1841.

Generic diagnosis: Shell large, depressed-globose, with
low spire; whorls convex, hirsute, brown with distinct
banding; body whorl rounded, umbilicate; aperture
oblique, lunate; lip dilated and somewhat reflected; colu-
mellar margin spread out by callus (ZILCH, 1960, trans-
lation).

The modern range of Lysinoe includes parts of Guate-
mala, Honduras, El Salvador, and the Mexican state of
Chiapas. Three species are recognized: L. ghiesbreghtu, L.
eximia (Pfeiffer, 1844), and L. starretti Thompson, 1963.
The ranges of the latter two species are not well known.
Lysinoe ghiesbreghtu is a large, conspicuous snail, gathered
for food by the native peoples of Guatemala and Chiapas
(MARTENS, 1890-1901; D. E. Breedlove, personal com-
munication).

The only species originally included in Aglaja Albers,
1850, was Helix ghiesbreghtu. Lysinoe was proposed ex-
plicitly as a replacement name for Aglaza [sic] Albers, non
Renier, and therefore takes the same type-species. A later

The Veliger, Vol. 27, No. 2

Page 202

B. Roth, 1984

designation (ALBERS, 1860) of Helix audouinn Orbigny,
1835, as type-species of Ag/aja is invalid. Opinion 427 of
the International Commission on Zoological Nomencla-
ture rejected Aglaia [sic] Renier, 1804, for nomenclatorial
purposes but reserved Aglaja Renier, 1807, for further
consideration. Priodontura H. Fischer, 1899, was pro-
posed as a replacement name for the preoccupied Odon-
tura P. Fischer & Crosse.

Lysinoe breedlovei Roth, spec. nov.
(Figures 1-3, 5, 6, 11, 15)

“Helix” sp., GARDNER, 1945:18, 167; pl. 18, figs. 1-3.

[?] Lysinoe, GARDNER, 1945:177.

Helix leidy: Hall & Meek, PAMPE, 1974:292-293 (in part),
pl. 1, figs. 1-7. Non Hall & Meek, 1855:394.

Oreohelix granger: Cockerell & Henderson, PAMPE, 1974:
293, pl. 2, figs. 11, 12. Non Cockerell & Henderson,
1912:231.

Diagnosis: Lysinoe with depressed-trochoid shell, about
4.75 whorls, irregular papillation, large, funicular um-
bilicus with circumumbilical ridge, narrowly shouldered
whorls, and greatest width below middle of body whorl.

Description of holotype: Shell moderately thin, de-
pressed-trochoid, broadly umbilicate; umbilicus funicular,
contained about 6.7 times in diameter. Spire profile faintly
convex; whorls of spire convex, narrowly, roundly shoul-
dered, suture impressed. Embryonic whorls apparently
about 1.5, with weak radial ribbing and a few scattered
papillae, pitted by erosion. Neanic whorls with low, ir-
regular, retractive growth rugae of varying sizes, com-
bined on early whorls with low granulose vermiculation
generally trending parallel to rugae. Rugae thickened,
curved backward, and somewhat bunched below suture.
From about third whorl on, also with discrete papillae,
most dense on upper 3 of body whorl, usually irregularly
spaced but in some places tending to fall in forwardly
descending series. Traces of nearly obsolete spiral striation
present above suture on some whorls of spire. Body whorl
narrowly, roundly shouldered, widest below middle of
whorl, somewhat compressed above and below periphery.
Base acuminate, with distinct ridge around umbilicus.
Growth rugae strong inside umbilicus; papillae sparingly

Explanation

Figures 1, 2, 3, 5, 6, and 11. Lysinoe breedlovei spec. nov.

Figures 1, 2, 3, and 5, holotype, TMM 40276-16, top, front,
lateral, and basal views; greater diameter 59.2 mm. Figure 6,
referred specimen, TMM 31281-41, lateral view; diameter 41.2
mm. Figure 11, referred specimen, TMM 31281-42, cross-sec-
tion; diameter 34.8 mm.

Figure 4. Pleurodonte (Pleurodonte) wilsoni spec. nov., referred
specimen, TMM 40206-8; diameter 22.0 mm.

Page 203

present. Last whorl slowly descending for last % turn
behind lip. Aperture subquadrate, markedly oblique, at
angle of 45° to axis of coiling; lip expanded and reflected.
Parietal wall thickly calloused. Diameter 59.2 mm, height
40.4 mm, diameter of umbilicus 8.9 mm; whorls 4.75.

Type material: Holotype: TMM 40276-16; Texas: Pre-
sidio County: mouth of Capote Creek north of Candelaria.
J. A. Wilson et al. coll., 28 June 1964. Colmena Tuff,
Vieja Group. Paratypes (4): TMM 40276-18A, 40276-
18B, 40276-28, 40276-29, same locality as holotype.

Referred material: TMM 31281-15 (1 specimen), 31281-
20 (2), 31281-25 (1), 31281-28 (1), 31281-31 (1), 31281-
35 (3), 31281-41 (1), 31281-42 (1). Presidio County: north
of Capote Creek, Candelaria area. J. A. Wilson et ai. coll.,
various dates between August 1960 and July 1962. Col-
mena Tuff.

TMM 40276-5 (1 specimen, cf. L. breedlovet). Presid-
io County: mouth of Capote Creek. J. A. Wilson coll., 7
October 1961. Colmena Tuff.

UCMP B-1362 (6 specimens, internal molds). Presidio
County: 3 mi (4.8 km) north of Candelaria on north and
south sides of mouth of Capote Creek; dark red-brown
tuff with numerous boulder conglomerate lenses; gastro-
pods in tuff about 70-90 ft (21-27 m) above base of Ter-
tiary section. J. A. Wilson coll. Colmena Tuff.

TMM 41211-1 (1 specimen, figured by PampeE, 1974,
pl. 1, figs. 4, 5), 41211-2 (1). Presidio County: 0.5 mi (0.8
km) south of where road from Middleton’s to Adobe Spring
leaves Rooney Red Tuff Lentil. J. A. Wilson coll., 17
June 1968. Chambers Tuff, Vieja Group.

TMM 41216-5 (1 specimen). Presidio County: Capote
Falls Ranch. J. A. Wilson et al. coll., 18 June 1968.
Chambers Tuff.

TMM 41579-2 (1 specimen). Brewster County: Alamo
de Cesario Creek. M. S. Stevens coll., 11 June 1973.
Unnamed lower member, Devil’s Graveyard Formation.

TMM 41672-22 (5 specimens). Brewster County: Pur-
ple Bench. J. A. Wilson e¢ al. coll., 28 June 1974. Devil’s
Graveyard Formation.

TMM 41715-3 (1 specimen). Brewster County: North
Fork of Alamo de Cesario Creek. M. S. Stevens coll., 18
June 1974. Skyline Channels, base of Bandera Mesa
Member, Devil’s Graveyard Formation.

of Figures 1 to 14

Figures 7, 8, and 10. Lysinoe ghiesbreghtu (Nyst, 1841), Holo-
cene, near San Cristobal de las Casas, Chiapas, Mexico, CAS
045384, top, lateral, and basal views; greater diameter 61.5 mm.

Figures 9 and 13. Polymita picta (Born, 1780), Holocene, Mesa
de Ovando, Oriente Province, Cuba, CAS 045385, top and front
views; specimen coated for photographing; greater diameter 34.0
mm.

Figures 12 and 14. Polymita texana spec. nov., holotype, TMM
40276-1, top and front views; greater diameter 38.5 mm.

Page 204

TMM 42019-19 (1 specimen). Brewster County: Red
Hill, east side, same level as Balanced Rock, Coffee Cup
Ranch. M. S. Stevens coll., 21 June 1977. Devil’s Grave-
yard Formation.

TMM 42151-5 (3 specimens). Brewster County: South
of Stone Corral. M. S. Stevens coll., 16 June 1977. Cotter
Channels, Bandera Mesa Member, Devil’s Graveyard
Formation.

I have not personally examined specimen TMM 41578-
3 from the “Skyline Red Ss.” (=Devil’s Graveyard For-
mation) figured by PAMPE (1974, pl. 1, figs. 1-3; as “Helix
leidy:’’) but from the illustration it is clearly L. breed-
lovet.

Additional description: Most of the paratypic and re-
ferred material agrees in character with the holotype. A
referred specimen from locality TMM 31281 shows bet-
ter than the holotype the extent to which the peristome
may turn outward at maturity (Figure 6). Some specimens
have been compressed dorsoventrally during preservation;
these show an artificially emphasized peripheral angula-
tion. Others have been compressed or skewed laterally.
Post-mortem changes aside, there seems to have been some
variation in height of spire and degree of depression of the
body whorl. A cross-section (Figure 11) shows that the
axis is perforate throughout growth and that the circum-
umbilical ridge is more acute on the early whorls.

The shell structure of Lysinoe ghiesbreghtu consists of
(1) a thin inner lining probably of complex-prismatic
structure (terminology after MACCLINTOCK, 1967); (2) a
thick crossed-lamellar layer with first-order lamellae par-
allel to growth lines, intertonguing with (3) a second,
equally thick, crossed-lamellar layer with first-order la-
mellae oriented at right angles to the first and parallel to
the direction of growth. Fracture sections on the inner lip
and body whorl of the holotype of L. breedlovei show
that, although the shell has recrystallized, these three basic
structural layers were originally present.

Referred specimen TMM 42019-19 shows a_pro-
nounced thickening and subsequent discordance of growth
rugae at the 1.5-whorl stage. This appears to represent
the change from embryonic to neanic shell growth.

One specimen, TMM 40276-5 (Figure 15), is excep-
tionally large. Although missing three quarters of the
fourth whorl, the remaining internal mold is 81.2 mm in
greatest diameter. The original diameter was probably in
excess of 95 mm. The axis is perforate and the whorl
cross-section like that of other specimens at hand. A small
amount of recrystallized shell remaining around the axis
shows shell layers of the same proportions as the holotype
of L. breedlovei.

Remarks: Lysinoe breedlovei closely resembles the Ho-
locene Lysinoe ghiesbreghtu (Nyst) (Figures 7, 8, 10) in
size, general proportions, rate of augmentation of the
whorls, and shape of aperture and umbilicus. The angle
of obliquity of the aperture, in relation to the coiling axis,

The Veliger, Vol. 27, No. 2

is about 40° in L. ghiesbreghtu. The umbilicus of L. breed-
lovei is wider (Figure 5) and the circum-umbilical ridge
of the base more pronounced. The body whorl of L. ghies-
breghtu is more tumid, with the widest part being near
the middle, rather than below it as in L. breedlovei. In
L. breedlovei the last whorl increases its rate of descent
along the coiling axis slowly over the last %4 turn (Figures
3, 6), whereas in L. ghiesbreghtu there is a sharp down-
turning about 1 cm behind the outer lip (Figure 8). Lys7-
noe ghiesbreghtu averages 5.1-5.25 whorls at maturity,
slightly more than L. breedlovei.

The spire and upper part of the body whorl of L. ghies-
breghtu bear fine periostracal hairs arranged in diagonal
series. Each of these is borne on a low, round, 0.1 mm-
wide papilla reflected in the underlying calcareous layer
of the shell. Papillae are present on the holotype of L.
breedlovei but are not as regularly disposed.

Lysinoe breedlovei is the same species reported as “‘He-
lix” sp. by GARDNER (1945) from beds she assigned to the
Oligocene, in Nuevo Leon, Mexico. Gardner herself noted
the similarity to Lysinoe. Her figured specimen (USNM
497132) and others are internal molds with minor traces
of shell remaining. They show no taxonomic characters
to separate them from L. breedlovei of the Vieja Group.
The occurrence is in a predominantly marine sequence.
At one locality (USGS 14023) the species was associated
with the estuarine mollusks Evodona and Ampullina and
the fluviatile gastropod Hemusinus, indicative of perma-
nent (not seasonal) running water. As discussed below
under “‘Age and Correlation,” the occurrence is significant
for marine-nonmarine temporal correlations. The speci-
men from the Yegua Formation (Eocene) at Ochoa, Ta-
maulipas, referred to Lysinoe by GARDNER (1945:177) is,
at this writing, temporarily unavailable for borrowing (T.
R. Waller, in /itt., 1983) but should also be examined in
this context.

The large, umbilicate land snail described as Helix spa-
tiosa Meek & Hayden, 1861, from the upper Paleocene
to middle or upper Eocene of the Rocky Mountain and
northern Great Plains regions, discussed as the type-species
of an unnamed new genus by TAyLor (1975), differs from
L. breedlovei in having six or more tightly coiled whorls
and apical sculpture of retractive riblets like those of Or-
eohelix.

The large Helix hesperarche Cockerell, 1914, from an
unknown locality but thought to be from the Eocene of
New Mexico, differs in having the whorls more tightly
coiled and the umbilicus narrower (0.12 times diameter,
versus 0.15-0.16 in L. breedlovet). HENDERSON (1935)
thought he recognized ““H.” hesperarche from “the O-2
Ranch, about 25 miles south of Alpine,” Texas. I have
not examined Henderson’s specimens, but it seems likely
that he had L. breedlovei.

PAMPE (1974), possibly taking a cue from Russell (in
GoLpIcH & ELMs, 1949), referred large specimens of L.
breedlovei to Helix leidyi Hall & Meek, 1855, and small-

B. Roth, 1984

Page 205

er internal molds of the same species to Oreohelix grangeri
Cockerell & Henderson, 1912. “Helix” leidy: from the
White River Group of South Dakota and Nebraska is a
globose form with narrow umbilicus, not assignable to any
modern genus of Helminthoglyptidae. Oreohelix grangeri
from the lower Eocene of Bighorn Basin, Wyoming, is a
depressed, carinate form that may represent young indi-
viduals of “Helix” spatiosa.

Etymology: The species is named for Dennis E. Breed-
love, Curator of Botany, California Academy of Sciences,
and expert on the flora of Chiapas, in recognition of his
personal investigations of Lysinoe and other Mexican mol-
lusks.

Polymita Beck

Polymita BECK, 1837:44. PILsBRY, 1895:187-189. TORRE Y
HUERTA, 1950:7-9. MORENO, 1950:21-35. ZILCH, 1960:
662.

Oligomita TORRE Y HUERTA, 1950:18.

Type-species: Helix picta Born, 1780.

Generic diagnosis: “Shell subglobular, brilliantly col-
ored, rather thin but solid, imperforate; whorls few (about
four), the last but little deflexed; aperture rounded, slight-
ly lunate, the peristome simple, not expanded or reflexed
except at axis, where it is reflexed and adnate over the
umbilical region; axis solid” (PILsBRy, 1895:188).

The modern range of the genus is restricted to Oriente
Province, eastern Cuba. The species of Polymita are ar-
boreal and probably feed on epiphytic fungi and lichens
(ToRRE Y HUERTA, 1950).

Polymita texana Roth, spec. nov.
(Figures 12, 14)

Diagnosis: Polymita with large, depressed-globose shell
with low spire, very rapidly enlarging body whorl, and
large first nuclear whorl.

Description of holotype: Shell large for the genus, thin,
depressed-globose, of 3.75 rapidly enlarging whorls; spire
low; suture not deeply impressed. Embryonic whorls about
1.3, smooth, demarcated from neanic whorls by a weak
constriction. Neanic whorls smooth, with almost obsolete,
rounded growth lines and impressed radial growth rests
at intervals of one half to one whorl. First neanic whorl
with two prominent radial rugae right after embryonic
whorls, and an impressed growth rest at first half whorl.
Prominent growth rests occurring at 1.8, 2.8, and 3.3
whorls, with an internal thickening of the shell wall at
each rest, followed by a sudden increase in internal whorl
diameter. Periphery broadly rounded; body whorl de-
scending slowly toward aperture, slightly constricted be-
hind outer lip. Outer lip weakly turned outward, inter-
nally thickened by low smooth ridge along margin. Parietal
wall simple, smooth; inner lip with thin secondary layer

of smooth callus reflected over columella. Major diameter
38.5 mm, minor diameter (incomplete) 27.2 mm, height
25.9 mm.

Type material: Holotype: TMM 40276-1. Texas; Pre-
sidio County: mouth of Capote Creek north of Candelaria.
Bill Brannan coll., 1957. Colmena Tuff, Vieja Group.

Remarks: The rapid rate of whorl expansion of the few-
whorled, subglobose shell, the steplike enlargement of
whorl diameter after a growth rest, and the smooth sec-
ondary callus reflection over the columellar region are all
distinctive characteristics of Polymita, and most similar to
Polymita picta (Born) (Figures 9, 13).

The holotype (the only known specimen) is a nearly
intact internal mold with pieces of shell remaining at the
apex, on the outer part of the body whorl back for 3 turn
from the outer lip, and around the columellar margin of
the aperture. It differs from P. picta in having 0.25-0.5
whorl less (based on large specimens of P. picta) and a
larger first nuclear whorl—1.6 mm in diameter compared
to 1.25 mm for P. picta. The shell has been slightly dis-
torted in preservation, but the spire probably was lower
originally than the average spire of P. picta. The outer lip
of the fossil turns out more strongly than that of P. picta.

The holotype is distinguishable from Humboldtiana by
its smooth surface, without any trace of granulose or pa-
pillose sculpture or the heavy, irregular growth wrinkles
characteristic of that genus. Many species of Humboldti-
ana have nuclear whorls the same size as this fossil; most
have a radially wrinkled protoconch, but this fine sculp-
ture is readily removed by erosion even in living snails.
Humboldtiana are narrowly umbilicate. The inner lip cal-
lus of the specimen at hand is broken at the lower end
and may originally have left exposed a small umbilical
chink, but the part that remains extends lower on the shell
and is more broadly spread onto the body whor! than in
any known Humboldtiana species.

Xerarionta Pilsbry

Xerarionta PILSBRY, 1913:382. PitsBRy, 1939:214-215.

Type-species: Arionta veitchu Tryon, 1866, ex Newcomb
MS (=Xerarionta levis canescens [Adams & Reeve,
1848)]).

Generic diagnosis: “Rather capacious, globose-conic or
depressed-globose shells, perforate or closed, copiously
variegated or sometimes white; the embryonic 1% whorls
with radial sculpture or nearly smooth; peristome mod-
erately or scarcely expanded, shortly dilated at the axial
insertion” (PILSBRY, 1939:214).

Formerly considered a subgenus of Micrarionta Ancey,
1880, Xerarionta was elevated to generic rank by MILLER
(1981). Its modern range includes the regions of Baja
California that are influenced by Pacific Ocean fogs (MIL-
LER, 1973; SMITH et al., in preparation), the southern
California Channel Islands, and the adjacent mainland.

The Veliger, Vol: 27-NorZ

Page 206

B. Roth, 1984

Xerarionta areolata occurs as fossils of Pleistocene or early
Holocene age on Isla Monserrate, Isla Espiritu Santo, and
the nearby Baja California mainland, but there is no prior
Tertiary record of the genus.

Xerarionta waltmilleri Roth, spec. nov.
(Figures 16, 17, 33)

Helix leidy: Hall & Meek, PAMPE, 1974:292-293 (in part),
pl. 1, figs. 8-10. Non Hatt & MEEK, 1855:394.

[?] Humboldttana UNDERWOOD & WILSON, 1974:596-597,
text-fig. 2.

Diagnosis: Xerarionta with depressed-globose shell, um-
bilicus filled by impressed callus pad, tumid body whorl,
and fine, even, overall granulation with granules aligning
diagonally.

Description of holotype: Shell large for the genus, de-
pressed-globose, imperforate. Spire profile slightly convex;
whorls of spire flattish to weakly rounded; suture scarcely
impressed until penultimate whorl. Embryonic whorls not
clearly demarcated from neanic whorls. Neanic whorls
sculptured with fine, even, overall granulation (best seen
by low-angle light), the granules close, aligning in diag-
onal series; and moderately prominent, retractive growth
rugae. Granulation weaker on base and perhaps also on
upper part of whorl below suture; locally appearing as
network of minute, diagonal, incised grooves. Body whorl
tumid, moderately compressed above the well-rounded pe-
riphery. Base inflated, umbilical region not strongly in-
dented. Last whorl slowly descending for last 4 turn and
weakly constricted just behind lip. Aperture semilunate,
oblique; lip narrowly expanded, reflected at base. With
impressed callus pad filling umbilical region. Parietal wall
with thin, simple callousing. Diameter 25.9 mm, height
19.8 mm; whorls 5.1.

Page 207

Type material: Holotype: TMM 40209-1006; Texas:
Presidio County: Reeves Bone Bed, 96 Ranch. J. A. Wil-
son et al. coll., December 1966. Upper part of Chambers
Tuff, Vieja Group. Paratypes (17): TMM 40209-502A,
40209-1007 through 40209-1022, same locality as holo-

type.

Additional description: The type lot consists of internal
molds ranging from poor to moderately good preservation.
The holotype retains considerable original shell. The reg-
ular granulose sculpture that suggests assignment to Xera-
rionta is preserved on the body whorl from right behind
the aperture to about % turn back (Figure 33) and at
several places on the penult. A strongly compressed para-
type also shows the same sculpture extending across the
base almost to the umbilical region.

Remarks: The relatively symmetrical, globose shape of
the body whorl, without sharp descent along the axis of
coiling, is suggestive of Xerarionta and most plainly seen
in X. areolata (Pfeiffer, 1845) (Figure 18). In Humboldti-
ana the body whorl expands at a greater rate and slopes
obliquely down and away from the coiling axis. The ap-
erture is more effuse. Granulose sculpture is present in
some species of Humboldtiana but is of a different type:
the granules tend to align along growth lines and often
merge with the growth rugae. They are often irregular in
size and only rarely produce anything like the fine, even,
overall, diagonally trending fabric of the surface of X.
waltmillert.

Granulose sculpture also occurs in Pleurodonte (Den-
tellaria), but here also the granules are aligned primarily
parallel to growth lines. The globose shape of X. walt-
milleri and its simple, weakly deflected aperture distin-
guish it from Pleurodonte or any similar camaenid genera.

The microsculpture in Xerarionta is varied, from smooth
with weak wrinkles of growth (X. areolata) to deeply cut

Explanation of Figures 15 to 33

Figure 15. Cf. Lysinoe breedlovei spec. nov., referred specimen,
TMM 40276-5, top view; greatest diameter 81.2 mm.

Figures 16, 17, and 33. Xerarionta waltmilleri spec. nov., ho-
lotype, TMM 40209-1006. Figures 16 and 17, top and front
views; greater diameter 25.9 mm. Figure 33, SEM photograph
of diagonal microsculpture obliquely crossing growth rugae
(curved horizontal ridges) on body whorl behind outer lip, x 20.7.

Figure 18. Xerarionta areolata (Pfeiffer, 1845), Holocene, shore
of Bahia Magdalena, Baja California Sur, Mexico, CAS 045386;
diameter 25.6 mm.

Figures 19, 20, 23, 24, and 25. Pleurodonte (Pleurodonte) wilsoni
spec. nov. Figures 19 and 20, holotype, TMM 40840-50, top
and basal views; greater diameter 24.5 mm. Figures 23 to 25,
paratype, TMM 40840-52, top, basal, and lateral views; greater
diameter 24.1 mm.

Figures 21 and 22. Pleurodonte (Dentellaria)(?) species, referred

specimen, TMM 40206-56, top and basal views; greater diam-
eter 17.7 mm.

Figure 26. Pleurodonte (Pleurodonte) isabella (Ferussac, 1821),
Holocene, St. John’s churchyard, Barbados, CAS 045388; great-
er diameter 23.6 mm.

Figures 27, 28. Plewrodonte (Dentellaria) anomala (Pfeiffer, 1848),
Holocene, Jamaica, CAS 045387; greater diameter 22.3 mm.

Figures 29, 30, and 31. Camaenid, genus and species indet.,
referred specimen, TMM 41579-49, top, front, and basal views;
greater diameter 16.1 mm.

Figure 32. Xerarionta redimita (Binney, 1858), Holocene, be-
tween Horse and Red Rock canyons, San Clemente Island, Cal-
ifornia, CAS 045389; SEM photograph of diagonal microsculp-
ture on lower part of body whorl behind outer lip, x 22.0.
Specimens in Figures 16 to 33 have been coated for photograph-

ing.

Page 208

by incised spiral grooves (X. intercisa [Binney, 1857], X.
pandorae [Forbes, 1850]). The only extant species with
minute overall granulation are X. redimita (Binney, 1858)
(Figure 32) from San Clemente Island, and X. kelletta
(Forbes, 1850) from Santa Catalina Island, California,
and the adjacent mainland. The microsculpture of X. kel-
lettii is often faint or reduced to minute diagonal grooves
between growth lines, especially on the base. A small
amount of granulation can sometimes be seen on the first
neanic whorl of X. areolata; no diagonal trend is evident.
Xerarionta levis (Pfeiffer, 1845) has granulose wrinkling
upon the first and second neanic whorls, much more ir-
regular than that of X. redimita and X. kellettu.

Xerarionta waltmilleri may be the same species re-
ported as Humboldtiana from the Garren Group, Hud-
speth County (UNDERWOOD & WILSON, 1974). As of this
writing, those specimens are temporarily unavailable for
borrowing (T. R. Waller, in litt., 1983) but should be re-
examined later.

Etymology: The species is named for Walter B. Miller
of the University of Arizona, in recognition of his many
contributions on the Helminthoglyptidae and other mol-
lusks of the American Southwest.

Superfamily CAMAENACEA
Family CAMAENIDAE

BisHop (1979) summarized the Tertiary species from
North America that have been assigned to the Camaeni-
dae. A species of Caracolus Montfort, 1810, C. aquilonaris
Bishop, 1979, has been recognized in the upper Oligocene
Whitney Member of the Brule Formation, White River
Group, Sheridan County, Nebraska. SOLEM (1978) com-
mented on the similarity between Hodopoeus crassus Pils-
bry & Cockerell, 1945 (described from an unknown lo-
cality but thought to be from the Eocene of the
southwestern United States), and several species of Jso-
meria Albers, 1850. COCKERELL (1914) suggested a rela-
tionship between his Helix hesperarche and West Indian
Camaenidae; the holotype, an internal mold, lacks the
apertural characters that could confirm this placement.

Pleurodonte Fischer von Waldheim

Pleurodonte FISCHER VON WALDHEIM, 1807:229. WuURTZ,
1955:119-120. Z1LcH, 1960:601.
Type-species: Helix lychnuchus Miller, 1774.

Subgenus Pleurodonte, sensu stricto

Subgeneric diagnosis: Shell solid, globose or depressed,
with low, convex, conical spire; body whorl rounded or
angulate, imperforate; aperture oblique, broader than high;
lip dilated and strongly thickened, mostly toothed, the limbs
connected by a more or less robust parietal callus, which
sometimes is also toothed (ZILCH, 1960, translation).
The modern range of Pleurodonte, sensu stricto is limited
to the Lesser Antilles. One or more other species occur in

The Veliger, Vola 275 NowZ

the Miocene of Carriacou, Grenadines (JUNG, 1971).
Pleurodontites Pilsbry, 1939, from the Tampa Limestone
(lower Miocene) is probably closely related. ““Pleurodonte”’
eohippina Cockerell, 1915, from the Sand Coulee Beds,
Eocene (Wasatchian), Clarks Fork Basin, Wyoming, was
regarded as a helicinid prosobranch and made the type-
species of a new genus, Eohipptychia, by BIsHoP (1980),
but the available information on the unique specimen is
not adequate to permit critical commentary on its ordinal
placement (SOLEM, in press).

BisHoP (1979) suggested that antecedents to Pleuro-
donte were once widespread throughout the Antilles but
that Pleurodonte has become extinct on Cuba, Hispaniola,
and Puerto Rico. The new species next described and the
following one show that Pleurodonte was already differ-
entiated in North America by the late Eocene and that at
least two types of shell form were present at that time.

Pleurodonte (Pleurodonte) wilsoni Roth, spec. nov.
(Figures 4, 19, 20, 23-25)

Polygyra veternior (Cockerell), PAMPE, 1974:293-294 (in
part), pl. 2, figs. 5-7. Non Helix veterna veternior
COCKERELL, 1915:117.

Diagnosis: Plewrodonte with depressed, tumid, imperfo-
rate shell, 4.7-5.1 whorls, periphery rounded to angular,
body whorl sharply deflected downward behind aperture,
lip thickened but not dentate.

Description: Shell small for the subgenus, depressed, im-
perforate. Spire low, obtuse; spire profile convex; suture
lightly impressed, more deeply incised around last 0.5-
0.75 whorl. Embryonic whorls not well differentiated from
neanic whorls. Surface apparently smooth, with blunt,
indistinct growth rugae. Body whorl narrow, with round-
ed or subangular periphery; base compressed, smooth,
flattish. Last whorl turning sharply downward behind ap-
erture. Aperture broadly crescentic, very oblique, at angle
of 60-70° to axis of coiling; lip expanded and strongly
thickened but not dentate; parietal wall callused, without
teeth. Diameter of holotype 24.5 mm, height 14.2 mm;
whorls 4.8.

Type material: Holotype: TMM 40840-50; TJexas: Pre-
sidio County: Chalk Gap Draw. J. A. Wilson coll., June
1965. Upper part of Chambers Tuff, Vieja Group. Para-
types (8): TMM 40840-52 (1), 40840-53 (7), same lo-
cality as holotype.

Referred material: TMM 40206-8 (1 specimen), 40206-
54 (1), 40206-55 (1). Presidio County: Northwest of Big
Cliff. J. A. Wilson coll., 19 June 1960. Lower part of
Chambers Tuff.

TMM 40209-502 (4 specimens; one figured by PAMPE,
1974, pl. 2, figs. 5-7, as “Polygyra veternior”; associated
with Little Egypt local fauna, not Candelaria local fauna
as stated). Presidio County: Reeves Bone Bed, 96 Ranch.

B. Roth, 1984

Radioisotopic

Page 209

AGUA FRIA-BUCK HILL AREA

Ages
(Ma)

Local Fauna

Rock Unit

Uo SIERRA VIEJA AREA
oOo
He
o ke
2)/oa
onlene Rock Unit Local Fauna
nl|<ce
= oO
z=
Ww Petan Basalt
z
Ww 3
Oo 2 Mitchell Mesa Rhy
) < :
@| 5 Capote Mountain Ash Spring
=i
oO {o) Tuff Airstrip
ina
lame fan) a| Bracks Rhyolite
< =)
xr ° A Little Egypt
Oo «| Chambers Tuff
> P
Porvenir
Ge oO
< [——— -=]| Buckshot Ignimbrite
3 ®
be) © ra Colmena Tuff
ww] Zz A Candelaria
Fe] w
1S) Gill Breccia
o| =
Ls pS | Jeff Conglomerate
z
>

|

Mitchell Mesa Rhyolite

Bandera Mesa

Member A Coffee Cup

&

Skyline

Unnamed

middle member

A Serendipity

Unnamed

I ;
ower member & Whistler
Squat

Devil's Graveyard Formation

46.9, 49.7

Figure 34

Correlation of rock units, radioisotopic ages, and mammal-based local faunas in Sierra Vieja and Agua Fria—Buck
Hill areas. Filled triangles indicate sources of land mollusks reported in this study. Radioisotopic ages from WILSON
et al. (1968) and WILSON (1978, and personal communication, 1983), corrected for new decay and abundance

constants (DALRYMPLE, 1979).

J. A. Wilson et al. coll., 1966. Upper part of Chambers
Tuff.

TMM 40283-82 (10 specimens). Jeff Davis County:
Ash Spring. J. A. Wilson coll., 16 June 1965. Vieja Group,
undifferentiated.

Additional description: The description given above is
composite, because no single specimen in the type lot shows
all the characters. All specimens are internal molds, with
scraps of recrystallized shell remaining, mainly in the su-
ture but occasionally around the aperture or on the spire.
The major variation is in the shape of the periphery, which
ranges from evenly rounded to subangular in the type lot.
The referred material from the Big Cliff locality (TMM
40206) is lenticular (Figure 4) with a distinctly angled
periphery. Material from the undifferentiated Vieja Group
at Ash Spring is rounded, with only a hint of angulation
showing on some specimens. Comparable variability is
known in some modern species of Pleurodonte, for example
P. acuta (Lamarck) illustrated by PitsBry (1889-1890,
pl. 26). It is also possible that sedimentary compaction
tends to emphasize the peripheral angulation, as in Lysv-
noe breedlovet.

Representative “mature” specimens (those with thick-
ened lip) measure:

No. of
Locality Diameter Height whorls
TMM 40840 24.1 mm 13.6mm = 4.75
2385 132 4.75
TMM 40206 Zell, 125 5.1
TMM 40209 20.5 W238) 4.75
1922 12.6 Sl
TMM 40283 24.1 17.0 5.0
23.6 10) 4.7
230 14.6 Sal
23.0 14.5 oF
22.8 14.2 4.9
22.2 14.3 4.7

Several specimens show a slight upward constriction of
the base of the last whorl directly behind the aperture.
This is a relatively common feature in Pleurodonte and
other genera of American Camaenidae.

Remarks: Pleurodonte wilsont resembles the Holocene
Pleurodonte isabella (Ferussac, 1821) (Figure 26) and sev-
eral other related species. The group was most compre-
hensively reviewed, at least for shell characters, by PILSBRY
(1889-1890, 1893-1895). The spire of P. isabella is more
domelike and the suture scarcely impressed at all until the
last whorl. An irregular or denticulate ridge runs along

Page 210

the basal lip of P. isabella; there is evidently no such ridge
in P. wilsoni. Pleurodonte lehneri (Trechmann, 1935) from
the Miocene of Carriacou, Grenadines, is also similar but
has a strong, prominent tooth in the middle of the upper
lip and two sometimes poorly developed denticles on the
basal lip. Its spire is often, although not invariably, higher,
and more domelike. Most specimens are less than 20 mm
in diameter. However, the holotype of “Helix” carriacou-
ensis (Trechmann, 1935), synonymized with P. lehneri by
JUNG (1971), is 24.6 mm wide.

Helix veterna veternior Cockerell, 1915, from the lower
Eocene of Wyoming, is a more globose form, apparently
known from immature specimens only. It does not have
the oblique aperture, descending last whorl, upwardly
constricted base, or any other characters that would per-
mit it to be associated with P. wilsoni.

Etymology: The species is named for John Andrew Wil-
son, who has contributed more than anyone else to the
knowledge of Vieja Group paleontology.

Subgenus Dentellaria Schumacher

Dentellaria SCHUMACHER, 1817:69, 230. WuRTzZ, 1955:125-
128. ZILCH, 1960:602.

Lucerna “Humphrey” SWAINSON, 1840:328. Non Willough-
by, 1816.

Type-species: Helix sinuata Miller, 1774.

Subgeneric diagnosis: Shell solid, depressed-globose to
lenticular; 4.5-6 whorls, finely and densely granulose; body
whorl rounded or carinate, descending toward the aper-
ture, umbilicate or imperforate; aperture very oblique,
broader than high; lip broadly reflected; basal lip with O-
5 teeth, the limbs connected by a toothless parietal callus
(ZILCH, 1960, translation).

Wurtz (1955) found the anatomical differences be-
tween Dentellaria and Pleurodonte, sensu stricto to be minor
and kept the two taxa separate (as infrasubgeneric “sec-
tions’’) solely on conchological grounds.

The modern range of Dentellaria is limited to Jamaica.
Two species occur at Bowden, Jamaica, in beds assigned
a Pliocene age (BIsHop, 1979). SOLEM (1978) assigned
Kanabohelix kanabensis (White, 1876), from the upper
Cretaceous of Utah, to the Camaenidae; he remarked on
its similarities to Dentellaria, but kept the two genera sep-
arate. BISHOP (1980) considered K. kanabensis a helicinid
prosobranch on the basis of the form of its palatal barriers;
but because it retains internal whorl partitions, SOLEM (in
press) restored it to the Camaenidae.

Pleurodonte (Dentellaria)(?) species
(Figures 21, 22)

Description: Shell depressed, broadly umbilicate, with 3.8
whorls preserved at a diameter of 17.7 mm; nearly flat-
spired, with first whorl apparently depressed slightly be-
low level of second; suture distinct, shell wall thickened
on either side. Periphery rounded, widest above middle;

The Veliger, Vol. 27, No. 2

last preserved whorl narrow, cross-section taller than
broad; base narrowed, with acuminate circum-umbilical
ridge; umbilicus large, steep-sided. Apertural characters
not preserved (specimen immature).

Referred material: TMM 40206-56 (1 specimen). Tex-
as: Presidio County: Northwest of Big Cliff. J. A. Wilson
et al. coll., 19 June 1960. Lower part of Chambers Tuff,
Vieja Group.

Remarks: The single specimen at hand is an internal
mold with traces of thoroughly recrystallized shell re-
maining at the suture, on the parietal wall, and around
the umbilicus. Although the specimen is obviously im-
mature and shows none of the characters of an adult peri-
stome, it is similar to the Jamaican Pleurodonte (Dentel-
laria) anomala (Pfeiffer, 1848) (Figures 27, 28). The almost
flat spire with depressed first whorl and the narrow whorl
cross-section are similar in both. At the level of the suture,
the shell of P. anomala is thickened by a small spiral carina
to which the summit of the subsequent whorl is appressed.
The shell of the fossil is thickened (although not carinate)
at the same position, and the shell remaining outboard of
the suture is also quite thick. Pleurodonte anomala has
even, overall granulation. The only section of shell on the
fossil not too recrystallized to show the original surface is
around the umbilicus inside the last whorl; this is smooth
with faintly raised growth lines. The umbilicus is more
steeply walled and the base more acuminate than in P.
anomala.

Camaenid, genus and species indet.
(Figures 29-31)

Polygyra veternior (Cockerell), PAMPE, 1974:293-294 (in
part), pl. 2, figs. 8-10. Non Helix veterna veternior
COCKERELL, 1915:117.

Description: Shell lenticular, umbilicate, of 5.1 whorls.
Spire low, whorls little inflated; suture moderately im-
pressed, distinct. Embryonic whorls not well differentiat-
ed from neanic whorls. Whorls narrowly, obtusely shoul-
dered; periphery rounded-subangulate, widest part above
middle of penult but descending below middle on body
whorl. Preserved sculpture of a few low, irregular, for-
wardly bowed, retractive growth rugae. Body whorl with
flat shoulder, not markedly descending until 0.1 whorl
behind aperture, where it turns down at angle of about
30° from horizontal. Base compressed, constricted upward
behind aperture; umbilicus 0.14 times diameter. Aperture
broadly ovate, very oblique, at angle of 60-70° to axis of
coiling; lip simple, turned outward but little thickened,
encroaching on umbilicus but not appressed at base. Pa-
rietal wall with thick wash of callus but no denticulation.
Diameter 16.1 mm, height 8.8 mm, diameter of umbilicus
2.4 mm.

Referred material: TMM 41579-49 (1 specimen). Tex-
as: Brewster County: Alamo de Cesario Creek. M. S. Ste-

B. Roth, 1984

vens coll., 11 June 1973. Unnamed lower member, Devil’s
Graveyard Formation.

Remarks: The single specimen consists of thoroughly re-
crystallized shell around a light, yellowish-gray, tuffa-
ceous siltstone matrix. Although quite well preserved, it
cannot be assigned to any known genus. The lenticular
shape and umbilicate base suggest Oreohelix Pilsbry, 1904
(Oreohelicidae) but the outward-turning lip and the sharp
terminal downward deflection of the body whorl are not
typically oreohelicid. In contrast, the slight upward con-
striction of the base behind the aperture is a feature seen
in several American genera of the Camaenidae. A con-
striction of about the same relative magnitude occurs in
several species of /someria Albers, 1850. Almost all living
species of Jsomeria are large-shelled (to a diameter of 70+
mm). The only one normally under 20 mm when adult is
I. minuta Solem, 1966. Several species of Labyrinthus Beck,
1837, become adult in the 15-20 mm diameter size range,
although most are larger (to 60 mm). In all modern species
the basal constriction is pronounced and the aperture pro-
vided with various denticles and lamellae.

The specimen was taken with numerous specimens of
a planorbid fresh-water gastropod discussed and illustrat-
ed by PAMPE (1974, pl. 2, figs. 1-4) under the name
Biomphalaria spectabilis (Meek).

AGE AND CORRELATION

The type locality of Lysinoe breedlovei, at the mouth of
Capote Creek on the Rio Grande about 2 mi (3.2 km)
north of Candelaria, is the source of the Candelaria local
fauna. This fauna, summarized by WILSON (1978, tables
1, 2, 14) is assigned to the Uintan North American Land
Mammal “Age” (BLACK & DAWSON, 1966; WILSON et al.,
1968; WILSON, 1978) (Figure 34). From a study of the
rodents, WooD (1974) suggested that the Candelaria local
fauna was slightly younger than the Myton local fauna
of the Uinta Formation of Utah.

The Colmena Tuff is bracketed stratigraphically by
radioisotopic dates based on potassium-argon analysis of
sanidine concentrates. Volcanic rock from the Gill Brec-
cia, underlying the Colmena Tuff, yielded an age deter-
mination of 40.0 + 2.0 Ma (WILSON et al., 1968, figs. 1,
2, table 3; sample “O”’). Corrected for the new *K decay
and abundance constants (DALRYMPLE, 1979) the deter-
mination is equivalent to 41 + 2 Ma. Three samples from
the Buckshot Ignimbrite, which overlies the Colmena Tuff,
yielded age determinations of 35.2 + 2.3 Ma, 34.7 + 2.0
Ma, and 38.6 + 1.2 Ma (WILSON et al., loc. cit.; samples
1, 2, and 2a respectively). The latter two determinations
were made from the same rock specimen; the authors give
reasons for favoring the older age determination. Cor-
rected for the new constants it sets a minimum age of
around 39 Ma for the Candelaria local fauna.

In the lower part of the Chambers Tuff, Lysinoe breed-
lovei, Pleurodonte wilsoni, and Pleurodonte (Dentella-
ria)(?) sp. are associated with the Porvenir local fauna.

Page 211

This fauna, summarized by WILSON (1978, tables 3-7,
14) is assigned to the early part of the Chadronian North
American Land Mammal “Age” (WILSON et al., 1968;
WILSON, 1978). The fossil localities lie stratigraphically
above the Buckshot Ignimbrite with its K-Ar ages as given
above, and below the Bracks Rhyolite, which has yielded
age determinations of 36.8 Ma (EVERNDEN ef al., 1964)
and 36.5 + 1.2 Ma (WILSON et al., 1968). Corrected for
the new constants, these determinations are equivalent to
37.7 and 37.4 + 1.2 Ma.

Pleurodonte wilsont and Xerarionta waltmilleri occur
in the upper part of the Chambers Tuff, associated with
the Little Egypt local fauna. This fauna, summarized by
WILSON (1978, tables 8-10, 14) is also Chadronian
(WILSON et al., 1968; WILSON, 1978). The Bracks Rhyo-
lite is absent in the areas where the Little Egypt local
fauna occurs (Chalk Gap Draw and the Reeves Bone
Bed), but a red sandstone that elsewhere lies immediately
under the Bracks is present. The age of this fauna is
therefore regarded as constrained by the same radioiso-
topic dates as the stratigraphically lower Porvenir local
fauna.

Pleurodonte wilson also occurs in the undifferentiated
Vieja Group at the Ash Spring locality in Jeff Davis
County (loc. TMM 40283), associated with the Ash Spring
local fauna. This fauna is summarized by WILSON (1978,
tables 12, 14). It is regarded as Chadronian, and younger
than the other local faunas of the Vieja Group based on
evolutionary position of vertebrate taxa (WILSON, 1978:
Dis

Correlation of units in the Agua Fria—Buck Hill area
(Figure 34) is based on unpublished information supplied
by J. A. Wilson (personal communication, 1983). Lysinoe
breedlovei occurs in association with the Whistler Squat
(early Uintan), Serendipity (late Uintan), Skyline, and
Coffee Cup (early Chadronian) local faunas. Radioiso-
topic ages (corrected) of 32.3 Ma from the Mitchell Mesa
Rhyolite, which overlies the Devil’s Graveyard Forma-
tion, and 33.0 Ma from basalt high in the Bandera Mesa
Member of the Devil’s Graveyard Formation set a mini-
mum age for the Coffee Cup local fauna. An isotopic age
of 42.7 Ma from tuff in the unnamed middle member sets
a maximum age for the Coffee Cup and Skyline local
faunas and a minimum age for the Serendipity local fau-
na. Age determinations of 43.9 Ma from biotite and 46.9
and 49.7 Ma from tuff in the unnamed lower member set
a maximum age for the Serendipity local fauna and brack-
et the Whistler Squat local fauna.

The Decade of North American Geology (DNAG) geo-
logic time scale (PALMER, 1983) places the Eocene-Oli-
gocene boundary at 36.6 Ma; dates between 36.6 and 40.0
Ma are classified as late Eocene. In most of the literature
on Vieja Group paleontology, however, the lower limit of
the Chadronian “age” and the base of the Oligocene are
treated as approximately coincident (cf. WILSON, 1978,
fig. 5). In Figure 34 the DNAG placement of the Eocene-
Oligocene boundary is followed; the boundary falls at or

Page 212

slightly above the stratigraphic level of the Bracks Rhyo-
lite. Magnetostratigraphy of the Vieja Group is in agree-
ment with these correlations (PROTHERO et al., 1982).

A number of North American land mollusks are known
from deposits regarded as correlative with the Colmena
Tuff or the Chambers Tuff, but only a few of the occur-
rences have been critically analyzed. The lower part of
the Sespe Formation, Ventura County, California, is of
Uintan (late Eocene) age (LILLEGRAVEN, 1979) and is the
source of Helminthoglypta? stocki Hanna, 1934. This large
land snail is definitely not a Helminthoglypta, but its prop-
er allocation and paleoclimatic implications are not yet
known. D. W. TayLor (1975, and in Ross, 1959 [1960])
reported three species of land snails of probable late Eocene
age and three others of probable Oligocene age from the
Flathead River valley, Montana-British Columbia. Early
Tertiary formations of the Bozeman Group in the Three
Forks Quadrangle, southwestern Montana, have yielded
a diverse molluscan fauna consisting of the genera Gas-
trocopta (four species), Pupoides (Ischnopupoides) (two
species), Radiocentrum (two species), Polygyrella, and Hel-
minthoglypta (ROTH, in press). The formations range in
age from probable middle or late Eocene (Uintan or ear-
lier) to early Oligocene (Chadronian). The assemblages
have a temperate aspect and suggest that a thermal strat-
ification—latitudinal, altitudinal, or both—existed during
this time. The temporal correlations, however, are mostly
inferential. TAYLOR (1975, tables 18, 27, 28, 31-33, figure
3) reported land mollusks of late Eocene to Oligocene age
from formations in central, southwestern, and northwest-
ern Wyoming. The full description of these terrestrial
mollusk faunas, their interrelationships, and time corre-
lation, remain for the future. For the present it may be
noted that the molluscan faunas of the northern Cordillera
have little in common with those of the Vieja Group.

Based on faunal correlation with the Chambers Tuff,
UNDERWOOD & WILSON (1974) assigned an age between
38 and 39 Ma to the tuff of the Garren Group in Hud-
speth County, Texas, that yielded specimens of Humboldt-
zana. Vertebrate remains from the same rock sequence
correlate with the Porvenir local fauna (early Chadroni-
an) (WILSON, 1978).

The Lysinoe breedlovei from Nuevo Leon occur low
in the upper of two marine sandstones containing a
“Vicksburg” molluscan fauna (GARDNER, 1945). The
Vicksburg Group of the Gulf Coastal Plain traditionally
has been regarded as Oligocene and correlated with the
Rupelian Stage of Europe (COOKE et al., 1943; BERG-
GREN, 1971). On the recent DNAG geologic time scale
(PALMER, 1983), the Rupelian Stage is entirely post-
Eocene in age, younger than 36.6 Ma. The Lysinoe occur
with Ampullina mississippiensis (Conrad), which is char-
acteristic of the Mint Spring Formation of the Vicksburg
Group in Mississippi and, according to Gardner, may be
restricted to that horizon. A recent faunistic study
(Dockery, 1982) adds no new information on Mint Spring
interregional correlations.

The Veliger, Vol; 274 New

PALEOECOLOGY anp PALEOCLIMATE

Compared to that of mammals, the average rate of evo-
lutionary change expressed in the morphology of land
snails is slow. The earliest fossil land snails, from the
Pennsylvanian and Permian periods, are assignable to ex-
tant families (SOLEM & YOCHELSON, 1979). Many mod-
ern genera make their first appearance in upper Creta-
ceous or Paleogene strata of North America, and in some
cases the shells present essentially no tangible differences
from those of species living today (ROTH, in press). If a
low rate of change is assumed to extend to physiological
tolerances as well—that is, if morphologic change is re-
garded as a fair sample of total evolutionary change—
land snail fossils can be viewed with confidence as indi-
cators of ancient environments.

At present the Rim Rock Country is part of the most
arid region of Texas, with normal annual precipitation
between 20 and 30 cm, most of it falling in summer. The
mean annual temperature is 16.9°C, and there is a mean
annual range of temperature of 19.5°C. The normal mean
temperature for the coldest month is 7.2°C (U.S. Depart-
ment of Commerce, 1968). The sparse vegetation includes
cacti, yucca, sotol, lechuguilla, and ocotillo, with sage-
brush and creosote bush on valley flats.

The modern distribution of Lysinoe ghiesbreghtu is
largely within the zone of seasonal temperate forest of
southern Mexico and Central America, with some exten-
sion into wet optimum forest types. The localities for which
definite information is available (see Appendix) are in
Pine-Oak Forest, Pine Forest (a facies of Pine-Oak For-
est), Pine-Oak-Liguidambar Forest, and Montane Rain
Forest, of BREEDLOVE’s (1981) classification of vegeta-
tional formations of Chiapas. The locality “Mosquito
Coast, north of Cape Gracias-a-Dios” (Honduras) by
MaRTENS (1890-1901) is definitely in error; his record
from Hacienda Buenavista, Guatemala, at elevation 4000-
5000 ft (1219-1524 m), is lower in altitude than any
material I have personally examined, although the appro-
priate forest types extend this low (BREEDLOVE, 1981).

The Pine-Oak Forest is an open forest association com-
posed of relatively few species of trees. Stands of pure
pine or oak occur in specialized edaphic situations. The
trees are commonly 15-40 m tall and variably spaced.
Epiphytes are sparse to common but heavy only in canyon
situations. The understory is usually herbaceous with a
few shrubs (BREEDLOVE, 1981).

The Pine-Oak-Liquidambar Forest is a diverse plant
association with many species of deciduous and semi-de-
ciduous trees, an abundance of epiphytes, and a variable
understory ranging from a dense association with many
species of shrubs, subshrubs, and vines, to a tall grassy
expanse with scattered shrubs. This formation is less open
than Pine-Oak Forest; the trees, which may be quite broad-
crowned, usually are close enough for their crowns to form
a continuous canopy. This is a temperate forest quite sim-
ilar to the diverse hardwood forests of the southeastern

B. Roth, 1984

United States, and depauperate elements of this associa-
tion occur at scattered locations in the Sierra Madre of
central and northern Mexico (BREEDLOVE, 1981; MI-
RANDA & SHARP, 1950).

Pine-Oak Forest ranges in altitude from 1300 to 2500
m with occasional patches as low as 1000 m. It exists
where there is a dry season of from three to six months.
Where the dry season is three months or less, it is replaced
by Pine-Oak-Liguidambar Forest. Where a dry season is
absent or at most only a few weeks in length, Pine-Oak-
Liquidambar Forest is replaced by Montane Rain Forest
or, above 2500 m elevation, by Evergreen Cloud Forest
(data from BREEDLOVE, 1981, fig. 5, and personal com-
munication). Rainfall is an important determinant of local
vegetational type, as seen in the difference between east
and west escarpments of the Chiapas Plateau: Pine-Oak-
Liquidambar Forest and Montane Rain Forest cover the
eastern escarpment; Pine-Oak Forest and Tropical De-
ciduous Forest occur on the drier west side (BREEDLOVE,
1981).

At San Cristobal de las Casas (16°44'N, 92°38'W; elev.
2755 m), typical of stations within the Pine-Oak Forest,
mean annual temperature is 14.8°C and there is a mean
annual range of temperature of 3.5°C. The normal mean
temperature for the coldest month (December) is 12.5°C;
that for the warmest months (June and July) is 15.9°C.
Annual rainfall is 123 cm, 6 cm of which (less than five
per cent of the annual total) falls in the period from No-
vember through February (Garcia, 1973). Such a climate
is classified as temperate and moist, with a long cool sum-
mer (Garcia, 1973). Using the data of mean annual tem-
perature and mean annual range of temperature, the nom-
ography method (AXELROD & BAILEy, 1969) gives
estimates of 197 days per year warmer than 14°C, a vir-
tual absence of freezing temperatures, and an equability
rating of 82. (Equability, as defined by Axelrod & Bailey,
here means freedom from extremes of both heat and cold.
A rating of 82 indicates an exceptionally equable climate.)

The rock enclosing the samples of Lysinoe breedlovei
from the Colmena Tuff is a pinkish-brown tuffaceous
siltstone, probably rhyolitic in composition, with intersti-
tial iron oxide staining. It was undoubtedly water-laid (J.
F. DeMouthe, personal communicaton) and suggests a
humid rather than an arid climate. During depositon of
the lower sedimentary facies of the Colmena Tuff, the
area was apparently a broad valley occupied by meander-
ing streams with active volcanoes not far distant (WILSON,
1978).

By analogy with Lysinoe ghiesbreghtu, L. breedlovei
indicates a highly equable, moist, temperate climate, either
with or without a winter dry season. The landscape was
forested with vegetation like the present-day seasonal tem-
perate forests of Chiapas (Pine-Oak or Pine-Oak-Liquid-
ambar) or, possibly, Montane Rain Forest. Perhaps an
analysis of the mammals of the Candelaria local fauna,
when all groups have been worked up, will indicate
whether a dense formation—Pine-Oak-Liquidambar or

Page 213

Montane Rain Forest—or the relatively open Pine-Oak
Forest is the more likely. There would have been a min-
imum of 123 cm of precipitation annually.

Lysinoe ghiesbreghtu lives at altitudes of about 1800-
2700 m. The regional geology of Trans-Pecos Texas in-
dicates that the rocks of the Vieja Group formed at lower
elevations and have been raised to their present altitude
(1000-2000 m) since Eocene time. The strata containing
the Barrilla flora in the neighboring Davis Mountains,
probably contemporaneous with the Chambers Tuff, were
most likely deposited at or below 300 m altitude (AXELROD
& BAILEY, 1976). Fossil floras of the Rio Grande depres-
sion, New Mexico, have undergone 1200 m of post-Eocene
uplift (AXELROD & BAILEY, 1976). The specimens of L.
breedlovei from Nuevo Leon were deposited in a brackish
marine environment and probably transported no great
distance from the interior; here also a lower elevation is
indicated. Although the precipitation and thermal param-
eters are inferred to have been similar to those of the
modern temperate Mexican forests, the topographic set-
ting was probably much lower and in more direct com-
munication with the coastline.

The information available on the modern habitats and
environments of the other genera is much less complete
or, in the case of Xerarionta, spans a broader range of
conditions.

Locality records of Polymita picta (morphologically the
closest species to P. texana) in the CAS collection indicate
that the species occurs on forested terraces inland from
Maisi, Oriente Province, over an altitude range of at least
180-460 m and elsewhere along the northeastern coast at
least as far west as Punta Guarico. The vegetation is sea-
sonal tropical forest with a high diversity of tree species,
including Cedrela mexicana, Ficus aurea, Ocotea leucoxylon,
Pithecellobtum saman, Roystonea regia, Spondias mombin,
and Zanthoxylum species (SEIFRIZ, 1943). Normal annual
rainfall in the range of P. picta is 114-152 cm. (At Punta
Maisi proper, one of the driest parts of Cuba and prob-
ably drier than the terraces inland, the annual precipita-
tion is 78 cm [PorRTIG, 1976].) For Oriente Province as a
whole the driest season is December through April; in
each of the months January through March there is less
than 6 cm of precipitation (SEIFRIZ, 1943, fig. 6). At Punta
Maisi the mean annual temperature is 26.3°C and there
is a mean annual range of temperature of 4.5°C (PORTIG,
1976). The equability rating determined by nomography
is 43. This is a true tropical climate with the normal mean
temperature of the coldest month above 18°C. The vege-
tational and thermal relations are inconsistent with those
based on L. ghiesbreghtu, although the general indications
of rainfall and a winter dry season are compatible.

There is inadequate information on the total range of
Pleurodonte (Dentellaria) anomala, the modern species
similar to the Dentellaria of the Porvenir local fauna, but
it does occur near Mandeville, Jamaica (PILSBRY &
Brown, 1910), on the bauxitic Manchester Plateau. Here
the original forest has been much modified by agriculture

Page 214

and grazing, but the tree species are elements of the Wet
Limestone Forest, a seasonal formation (ASPREY &
RopsBins, 1953). Rainfall is between 150 and 200 cm an-
nually with “few months” with less than 10 cm. The
climate is tropical.

Pleurodonte (Pleurodonte) occurs in the Lesser Antilles;
P. (P.) isabella, one of the species similar to P. (P.) wil-
soni, lives on Barbados. At Bridgetown, Barbados, the
annual rainfall is 130 cm; at Dunscombe it is 218 cm
(PorTIG, 1976). March is the driest month, August the
wettest. At Bridgetown the mean annual temperature is
26.3°C and there is a mean annual range of temperature
of 2.0°C. The equability rating is 44. The climate is,
therefore, similar to that in the range of Polymita picta.

Xerarionta now occurs on the southern California
Channel Islands and the adjacent mainland, and along
the western part of Baja California between latitudes 24-
31°N. The Baja California occurrences are all within the
arid, subtropical to tropical Sonoran Desert. Avalon, San-
ta Catalina Island (in the range of X. kelletti), has a mean
annual temperature of 14.5°C and a mean annual range
of temperature of 7.2°C, an equability rating of 72, and
annual precipitation of about 33 cm (ELFORD, 1970).
Representative stations within the Sonoran Desert range
of the genus include El] Rosario (mean annual tempera-
ture 17°C; mean annual range of temperature 10°C), Ba-
hia Magdalena (21.5°C; 8.5°C), and Vizcaino (19°C; 8.5°C)
(AXELROD, 1979, fig. 3). Equability ratings range from
54 to 64. The nomogram indicates more than 212 days
warmer than 15°C at El Rosario, more than 281 days
warmer than 17°C at Bahia Magdalena. These are among
the mildest and least thermally variable stations in the
Sonoran Desert.

The development of the Sonoran Desert as an arid
environment of regional extent was an event of latest Ter-
tiary and Quaternary time (AXELROD, 1979). Older en-
vironments of Tropic Savanna, Dry Tropic Forest, Short-
tree Forest, and drier formations contributed the ancestors
of the plant taxa that now characterize the desert. While
it is not justifiable to conclude that Xerarionta waltmilleri
lived under arid conditions, on the analogy of plant history
it may have been an inhabitant of relatively xeric sites in
a seasonally dry tropical or subtropical forest.

From the composition of the Rancho Gaitan local fauna
of northeastern Chihuahua (early Chadronian, correlated
with the Little Egypt local fauna), FERRUSQUIA (1969)
inferred a woodland community, possibly with marshy
habitats, and (from the presence of ‘“thousands”’ of large
fresh-water gastropods) the existence of a neighboring body
of permanent water. Thermal parameters were not spec-
ified.

AXELROD & BAILEY (1976) interpreted a small fossil
flora from the Huelster Formation in the Barrilla Moun-
tains to represent the upper part of a dry mixed subtrop-
ical flora, analogous to modern vegetation in southern Ta-
maulipas and southward along the east front of the Sierra
Madre Oriental. The Huelster Formation is correlated

The Veliger, Vol: 275No 2

with the Chambers Tuff (both are overlain by volcanics
yielding radioisotopic ages in the 36-37 Ma range: WIL-
SON, 1978, table 15), so climatic inferences from the Bar-
rilla flora may also be applicable to the neighboring
Chambers Tuff.

Increasing amounts of caliche cement in the sediments
of the Chambers Tuff indicate that increasingly drier con-
ditions prevailed at the time of that unit’s deposition
(Harris, 1967, M.A. thesis, Univ. Texas Austin; fide
FERRUSQUIA, 1969). WILSON (1978:32) also concluded that
the paleoenvironment of the Chambers Tuff was ““more
open than that of the Colmena, more removed from direct
volcanic activity and probably dryer.”

In the Sierra Vieja area, Lysinoe breedlovei makes its
last appearance in the lower part of the Chambers Tuff;
its last appearance in the Agua Fria—Buck Hill area is
probably not much later in time. Its local disappearance
may be correlated with increasing aridity and/or decreas-
ing equability of climate. During: this interval its range
may have begun to retreat southward, and possibly alti-
tudinally upward—where the likelihood of preservation
in lowland basins would be less. Xerarionta waltmilleri
makes its first appearance in the upper part of the Cham-
bers Tuff. The presence of this genus is consistent with
drier and at least somewhat less equable conditions.

The climatic transition cannot have been too radical,
however, because Pleurodonte wilsoni remained present
throughout the interval represented by the Porvenir to
Ash Spring local faunas.

The sympatry in the Vieja Group of land mollusk gen-
era now widely separated is striking. Polymita, now re-
stricted to the eastern province of Cuba, was sympatric
with Lysinoe in western Texas during late Uintan time.
Two now allopatric subgenera of Pleurodonte coexisted in
early Chadronian time; Lysinoe has not yet been found at
the same localities with them but comes from related sites
yielding the Porvenir local fauna. Pleurodonte and Xera-
rionta were sympatrically associated with the Little Egypt
local fauna. The history of these genera since early Ter-
tiary time has involved both southward limitation of range
and assortment into different geographic areas. How much
of this change represents sorting out along environmental
gradients and how much is attributable to historical ac-
cident remains a subject for investigation. At present, and
presumably to a greater or lesser extent throughout the
Tertiary, a southward geographic shift from North Amer-
ica takes a taxon into an area of smaller and more disjunct
land masses, where isolation and the probability of chance
extinctions are higher.

In the late Eocene paleogeographic reconstruction of the
Caribbean region by SYKEs et al. (1982, fig. 11), the var-
ious land masses now inhabited by the genera of the Vieja
Group assemblage were more closely juxtaposed. The Ca-
ribbean Plate, including Central America south of the
Motagua Fault, Jamaica, and the region of the Lesser
Antilles, was some 1400 km farther west than at present.
Jamaica is pictured as adjacent to southern Mexico, the

B. Roth, 1984

Lesser Antilles directly south of eastern Cuba. Somewhat
earlier, 48 million years ago, Cuba was part of the East
Pacific-Caribbean Plate and adjacent to the Yucatan Pen-
insula (SYKES et al., 1982, fig. 9, top). The separation of
Baja California from mainland Mexico by the rifting open
of the Gulf of California is a relatively young event, per-
haps beginning only four million years ago, although a
proto-Gulf of California, resulting from extension behind
a trench-are system, may have existed as early as the Mio-
cene (KARIG & JENSKY, 1972).

These paleogeographic reconstructions do not, however,
eliminate the need to consider over-water dispersal in the
biogeography of Caribbean land snail genera. They mere-
ly change the map on which hypothetical routes of dis-
persal must be plotted. For instance, depending on the
(conjectural) emergence of the Nicaragua Rise, Lysinoe
may have reached the portion of Central America on the
Caribbean Plate either over water or by land in Paleogene
time; or it may have made a shorter trip by land when
Central America and Mexico became juxtaposed in the
Miocene, between 20 and 7 Ma (SYKES et al., 1982, fig.
9, center and bottom).

Sympatry of taxa now widely separated is proving to
be a common phenomenon in Tertiary faunas of western
North America (ROTH, in press). The same has been found
true for plants (AXELROD & BAILEY, 1969:178-179):

“No Tertiary flora is duplicated exactly in any one area
by modern vegetation. In part the problem [in analyzing
paleoclimates] is one of species extinction, but also trou-
blesome is the fact that living plants most similar to those
of a fossil flora regularly contribute to forests that live in
widely separated regions, and under different climates.
For example, Miocene floras from central California to
Washington are composed of plants whose nearest rela-
tives are found in the conifer forests of the western United
States, in the mixed deciduous hardwood forests of the
eastern United States and in the related forests of China
and Japan.”

The property of equability, permitting year-long growth,
and the absence of frost permit tropical plants to live to-
gether with many species found in temperate regions, as
occurs in the Sierra Madre Oriental of Mexico (MIRANDA
& SHarP, 1950; AXELROD & BAILEY, 1969) and in the
zone of seasonal temperate forest in Chiapas. Climates of
high equability were widespread in North America dur-
ing the Eocene (AXELROD & BAILEY, 1969). The vegeta-
tion of the Mexican areas mentioned (including the Chia-
pas Plateau) includes a considerable number of species,
among them the forest-dominant oaks and pines, that seem
to have had a northern origin and relationships (MIRANDA
& SHARP, 1950). The similarity of the Pine-Oak-Liquid-
ambar Forest to the hardwood forests of the southeastern
United States has already been mentioned: many plant
species in eastern Mexico have very similar or identical
counterparts in the eastern U.S. Miranda & Sharp re-
garded 16% of 200 species that occur frequently in the
major temperate communities of eastern Mexico as be-

Page 215

longing to this category. GRAHAM (1973) listed 21 iden-
tical species and 12 species-pairs among the arborescent
(tree and shrub) genera common to the eastern U.S. and
eastern Mexico. The distributions of these species and
species-pairs are now disjunct (compare MIRANDA &
SHARP, 1950, fig. 12), but the evidence points to a former
continuity around the northwest Gulf of Mexico and for
unknown distances further north and west. The finding
of Lysinoe, a snail associated with the temperate Mexican
forests, in the Eocene of western Texas, supports this
scenario. However, the presence of other snail genera now
inhabiting more tropical forests suggests that the forest
elements may already have been somewhat mixed.

In summary, the land mollusk sequence is consistent
with a transition, over late Uintan-early Chadronian time,
from a highly equable, moist and temperate climate to one
more arid and less equable. The beginning of the south-
ward retreat of the ranges of several modern genera may
be in evidence. Genera now allopatric were formerly sym-
patric. On the model of plant communities, climatic equa-
bility is probably an important factor regulating northern
range limits, and perhaps generic diversity as well.

ACKNOWLEDGMENTS

For the opportunity to study Vieja Group land snails, I
thank John Andrew Wilson and Dwight W. Taylor. Drs.
Wilson, Jason A. Lillegraven, Walter B. Miller, Alan
Solem, Eugene V. Coan, and David R. Lindberg have
read drafts of the manuscript and made helpful sugges-
tions. I am grateful to Dennis E. Breedlove for informa-
tion on the modern habitat of Lysinoe and its climatic
implications, and deeply indebted to him, Luis F. Baptis-
ta, Kenneth E. Lucas, and others who collected mollusks
in Chiapas for the California Academy of Sciences (under
permit from the Secretaria de Agricultura y Ganaderia).
Fred G. Thompson supplied information on Lysinoe in
the Florida State Museum. Melissa Winans (TMM) and
David R. Lindberg (UCMP) kindly made available spec-
imens from the collections under their care. Jean F.
DeMouthe contributed a lithologic analysis. Thomas R.
Waller, Frederick J. Collier, and Jann Thompson advised
on specimens in the USNM. Frank Almeda and Peter U.
Rodda (CAS) facilitated the investigation in various ways.
SEM photographs were taken in the SEM facility of the
Department of Entomology, CAS, with competent aid from
Mary Ann Tenorio and Eduardo Almeida. Photographs
1-14 are the work of Jeanne M. Lynch. Breedlove’s field
work in Chiapas was supported by National Science
Foundation grants GB-29483x, DEB-7912213, and DEB-
7923274. A donation by Mrs. Rozaline Johnson sup-
porting illustration of the paper is gratefully acknowl-
edged.

LITERATURE CITED

ADAMS, H. & A. ADaMsS. 1854-1858. The genera of Recent
Mollusca, vol. 2. John van Voorst: London. 661 pp.

Page 216

The Veliger, Vol. 27, No. 2

ALBERS, J.C. 1850. Die Heliceen nach nattirlicher Verwandt-
schaft systematisch geordnet. Berlin. 262 pp.

ALBERS, J.C. 1860. Die Heliceen nach natiirlicher Verwandt-
schaft systematisch geordnet. Zweite Ausgabe (revised by E.
von Martens). Wilhelm Engelmann: Leipzig. 359 pp.

Asprey, G. F. & R. G. Rossins. 1953. The vegetation of
Jamaica. Ecol. Monogr. 23(4):359-412.

AXELROD, D. I. 1979. Age and origin of Sonoran Desert vege-
tation. Occas. Pap. California Acad. Sci. 132. 74 pp.

AXELROD, D. I. & H. P. BaiLtey. 1969. Paleotemperature
analysis of Tertiary floras. Palaeogeog. Palaeoclimatol. Pa-
laeoecol. 6(1):163-195.

AXELROD, D. I. & H. P. BAILEy. 1976. Tertiary vegetation,
climate, and altitude of the Rio Grande depression, New
Mexico—Colorado. Paleobiology 2(3):235-254.

Beck, H. 1837-1838. Index molluscorum praesentis aevi mu-
sel principis augustissimi Christiani Frederici. Copenhagen.
124 pp., 8 pls.

BEQUAERT, J. C. 1957. Land and freshwater mollusks of the
Selva Lacandona, Chiapas, Mexico. Bull. Mus. Compar.
Zool. 116(4):204-227.

BEQUAERT, J. C. & W. B. MILLER. 1973. The mollusks of the
arid southwest with an Arizona check list. Univ. Arizona
Press: Tucson. 271 pp.

BERGGREN, W. A. 1971. Tertiary boundaries and correlations.
Pp. 693-809. Jn: B. M. Funnell & W. R. Riedel (eds.),
The micropaleontology of oceans. Cambridge Univ. Press:
Cambridge.

BisHop, M. J. 1979. A new species of Caracolus (Pulmonata:
Camaenidae) from the Oligocene of Nebraska and the biotic
history of the American camaenid land snails. Zool. J. Linn.
Soc. 67(3):269-284.

BisHop, M. J. 1980. Helicinid land snails with apertural bar-
riers. J. Moll. Stud. 46(3):241-246.

BLaAck, C. C. & M. R. DAwson. 1966. A review of late Eocene
mammalian faunas from North America. Amer. J. Sci.
264(5):321-349.

BREEDLOVE, D. E. 1981. Flora of Chiapas. Part 1, Introduc-
tion to the flora of Chiapas. California Acad. Sci.: San Fran-
cisco. 35 pp.

Burcu, J. B. & F. G. THompson. 1957. Three new Mexican
land snails of the genus Humboldtiana. Occas. Pap. Mus.
Zool. Univ. Michigan 590. 11 pp., 5 pls.

CockERELL, T. D. A. 1914. Tertiary Mollusca from New
Mexico and Wyoming. Bull. Amer. Mus. Natur. Hist. 33(6):
101-107.

CockERELL, T. D. A. 1915. Gastropod Mollusca from the
Tertiary strata of the west. Bull. Amer. Mus. Natur. Hist.
34:115-120.

CocKERELL, T. D. A. & J. HENDERSON. 1912. Mollusca from
the Tertiary strata of the west. Bull. Amer. Mus. Natur.
Hist. 31:229-234.

Cooke, C. W., J. GARDNER & W. P. Wooprinc. 1943. Cor-
relation of the Cenozoic formations of the Atlantic and Gulf
coastal plain and the Caribbean region. Bull. Geol. Soc.
Amer. 54(11):1713-1722, 1 pl.

DALRYMPLE, B. D. 1979. Critical tables for conversion of K-Ar
ages from old to new constants. Geology 7(11):558-560.

DerForp, R. K. 1958. Tertiary formations of the Rim Rock
Country, Presidio County, Trans-Pecos Texas. Texas J.
Sci. 10(1):1-37.

Dockery, D. T., III. 1982. Lower Oligocene Bivalvia of the
Vicksburg Group in Mississippi. Mississippi Dept. Nat.
Res. Bur. Geol. Bull. 123. 261 pp.

ELrorp, C. R. 1970. Climate of California. Climatography of
the United States, no. 60-4. U.S. Dept. Commerce. 57 pp.

EVERNDEN, J. F., D. E. SavaGe, G. H. Curtis & G. T. JAMEs.
1964. Potassium-argon dates and the Cenozoic mammalian
geochronology of North America. Amer. J. Sci. 262(2):145-
198.

Ferrusquia V., I. 1969. Rancho Gaitan local fauna, early
Chadronian, northeastern Chihuahua. Bol. Soc. Geol. Mex-
icana 30(2):99-138.

FIscHER, H. 1899. Note sur l’Helix humboldtiana Valenciennes
avec quelques remarques sur le sous-genre Lysinoe et sur la
section Odontura. J. de Conchyl. 47(4):297-304.

FiscHER, P. & H. Crosse. 1870-1902. Etudes sur les mol-
lusques terrestres et fluviatiles du Mexique et du Guatema-
la. Mission Scientifique au Mexique et dans l’Amérique
Centrale, Recherches Zoologiques, pt. 7, 1:1-702, pls. 1-
Eile

FISCHER VON WALDHEIM, G. 1807. Museum Demidoff, vol.
3. Imperial University: Moscow. 329 pp., 6 pls.

Garcia, E. 1973. Modificaciones al sistema de clasificacién
climatica de Képpen. Univ. Nac. Auton. México, México.
246 pp.

GARDNER, J. 1945. Mollusca of the Tertiary formations of
northeastern Mexico. Geol. Soc. Amer. Mem. 11. 332 pp.,
28 pls.

Go.picH, S. S. & M. A. ELms. 1949. Stratigraphy and pe-
trology of the Buck Hill Quadrangle, Texas. Bull. Geol.
Soc. Amer. 60(7):1132-1183.

GRAHAM, A. 1973. History of the arborescent temperate ele-
ment in the northern Latin American biota. Pp. 301-314.
In: A. Graham (ed.), Vegetation and vegetational history of
northern Latin America. Elsevier Scientific Publishing Co.:
Amsterdam.

HALL, J. & F. B. MEEK. 1855. Descriptions of new species of
fossils, from the Cretaceous formations of Nebraska with
observations upon Baculites ovatus and B. compressus, and
the progressive development of the septa in baculites, am-
monites, and scaphites. Mem. Amer. Acad. Arts Sci., n. ser.
5(2):379-411.

HENDERSON, J. 1935. Fossil non-marine Mollusca of North
America. Geol. Soc. Amer. Spec. Pap. 3. 313 pp.

JuNG, P. 1971. Fossil mollusks from Carriacou, West Indies.
Bull. Amer. Paleontol. 61(269):147-262.

Karic, D. E. & W. JENsky. 1972. The proto-Gulf of Cali-
fornia. Earth Planet. Sci. Letters 17:169-174.

LILLEGRAVEN, J. A. 1979. A biogeographical problem involvy-
ing comparisons of later Eocene terrestrial vertebrate faunas
of western North America. Pp. 333-347. In: J. E. Gray &
A. J. Boucot (eds.), Historical biogeography, plate tectonics,
and the changing environment. Oregon State Univ. Press:
Corvallis.

MacCLintTock, C. 1967. Shell structure of patelloid and bel-
lerophontid gastropods (Mollusca). Peabody Mus. Nat. Hist.
Bull. 22. 140 pp., 32 pls.

MartTENs, E. von. 1890-1901. Biologia Centrali-Americana.
Land and freshwater Mollusca. R. H. Porter: London.
xxviil + 706 pp., 44 pls.

MILLER, W. B. 1973. Ecology and distribution of Helmintho-
glyptidae (Pulmonata) in Baja California. Echo 5:37.
MILLER, W. B. 1981. Helminthoglypta reederi spec. nov. (Gas-
tropoda: Pulmonata: Helminthoglyptidae) from Baja Cali-

fornia, Mexico. Veliger 24(1):46-48.

MIRANDA, F. & A. J. SHARP. 1950. Characteristics of the
vegetation in certain temperate regions of eastern Mexico.
Ecology 31(3):313-333.

Moreno, A. 1950. Estudio anatomico del género Polymita Beck.
Mem. Soc. Cubana Hist. Natur. 20(1):21-35, pls. 12-22.

B. Roth, 1984

PALMER, A. R. 1983. The Decade of North American Geology
1983 geologic time scale. Geology 11(9):503-504.

Pampe, W.R. 1974. A preliminary survey of fresh-water early
Tertiary invertebrates from Trans-Pecos Texas. Trans. Gulf
Coast Assoc. Geol. Soc. 24:291-302.

PiusBry, H. A. 1889-1890. Helicidae:—Vol. III. Manual of
conchology, ser. 2, 5:1-176, pls. 1-44 [1889]; 177-216, pls.
45-64 [1890].

Pitspry, H. A. 1893-1895. Guide to the study of helices (He-
licidae, Vol. 7). Manual of conchology, ser. 2, 9:1-48, pls.
1-14 [1893]; 49-160, pls. 15-40 [1894]; 161-336 & appen-
dix 1-126, pls. 41-71 [1895].

Piussry, H. A. 1913. Notes upon some Lower Californian
helices. Proc. Acad. Natur. Sci. Phila. 65:380-393.

Piussry, H. A. 1939. Land Mollusca of North America (north
of Mexico). Monog. 3, Acad. Natur. Sci. Phila. 1(1):1-573.

Pitssry, H. A. & A. P. BRown. 1910. The Mollusca of
Mandeville, Jamaica, and its environs. Proc. Acad. Natur.
Sci. Phila. 62:510-535.

Piyspry, H. A. & T. D. A. COCKERELL. 1945. Hodopoeus, a
fossil astray. Nautilus 58(4):116-117.

Portic, W. H. 1976. The climate of Central America. Pp.
405-478. In: W. Schwerdtfeger (ed.), Climates of Central
and South America. World Survey of Climatology, vol. 12.
Elsevier Scientific Publishing Co.: Amsterdam.

PROTHERO, D. R., C. R. DENHAM & H. G. FARMER. 1982.
Oligocene calibration of the magnetic polarity time scale.
Geology 10(12):650-653.

Ross, C. P. 1959 [1960]. Geology of Glacier National Park
and the Flathead Region, northwestern Montana. U.S. Geol.
Surv. Prof. Pap. 296. 125 pp.

Rotu, B. In press. Land mollusks (Gastropoda: Pulmonata)
from early Tertiary Bozeman Group, Montana. Proc. Calif.
Acad. Sci.

SCHUMACHER, C. F. 1817. Essai d’un nouveau systéme des
habitations des vers testacés. Schultz: Copenhagen. 287 pp.

SEIFRIZ, W. 1943. The plant life of Guba. Ecol. Monog. 13(4):
375-426.

SMITH, A. G., W. B. MILLER, C. C. CHRISTENSEN & B. ROTH.
In preparation. Land Mollusca of Baja California, Mexico.

SOLEM, A. 1978. Cretaceous and early Tertiary camaenid land
snails from western North America (Mollusca: Pulmonata).
J. Paleontol. 52(3):581-589.

SOLEM, A. In press. Lost or kept internal whorls: ordinal dif-
ferences in land snails. J. Moll. Stud., Suppl. 12a.

SOLEM, A. & E. L. YOCHELSON. 1979. North American Pa-
leozoic land snails, with a summary of other Paleozoic non-
marine snails. U.S. Geol. Surv. Prof. Pap. 1072. 42 pp., 10
pls.

STEVENS, J. B.. M. S. STEVENS & J. A. WiLson. In press.
Devil’s Graveyard Formation (new), Eocene and Oligocene
age, Trans-Pecos Texas. Texas Memor. Mus.

SwaInson, W. 1840. A treatise on malacology, or shells and
shell-fish. Longman, Orme, Brown, Green & Longmans:
London. 419 pp.

Sykes, L. R., W. R. McCann & A. L. Karka. 1982. Motion
of Caribbean Plate during last 7 million years and impli-
cations for earlier Cenozoic movements. J. Geophys. Res.
87(B13):10656-10676.

TayLor, D. W. 1975. Early Tertiary mollusks from the Pow-
der River Basin, Wyoming-Montana, and adjacent regions.
USS. Geol. Surv. Open-file Rep. 75-331. 515 pp.

Torre Y Huerta, C. DELA. 1950. El género Polymita. Mem.
Soc. Cubana Hist. Natur. 20(1):5-20, pls. 1-11.

U.S. DEPARTMENT OF COMMERCE. 1968. Climatic atlas of the

Page 217

United States. Govt. Printing Office: Washington, D.C. 80

PP-

UNDERWOOD, J. R., JR. & J. A. WiLson. 1974. Earliest known
occurrence of land snail Humboldtiana: from tuff of Garren
Group (Oligocene), Trans-Pecos Texas. J. Paleontol. 48(3):
596-597.

Witson, J. A. 1971. Early Tertiary vertebrate faunas, Vieja
Group, Trans-Pecos Texas: Agriochoeridae and Merycoi-
dodontidae. Texas Memor. Mus. Bull. 18. 83 pp.

WILson, J. A. 1978. Stratigraphic occurrence and correlation
of early Tertiary vertebrate faunas, Trans-Pecos Texas. Part
1: Vieja area. Texas Memor. Mus. Bull. 25. 42 pp.

WILSON, J. A., P. C. Twiss, R. K. DEForD & S. E. CLABAUGH.
1968. Stratigraphic succession, potassium-argon dates, and
vertebrate faunas, Vieja Group, Rim Rock Country, Trans-
Pecos Texas. Amer. J. Sci. 266(7):590-604.

Woop, A. E. 1974. Early Tertiary vertebrate faunas, Vieja
Group, Trans-Pecos Texas: Rodentia. Texas Memor. Mus.
Bull. 21. 112 pp.

Wurtz, C. B. 1955. The American Camaenidae (Mollusca:
Pulmonata). Proc. Acad. Natur. Sci. Phila. 107:99-143.
ZILCH, A. 1960. Gastropoda, Teil 2, Euthyneura. Handbuch

der Palaozoologie 6(2)(4):601-834.

APPENDIX:
Locality Records for Lysinoe gheisbreghti

Mexico: Chiapas: Municipio Teopisca, 10 km N of Teopisca,
elev. 7000 ft (2134 m), D. E. Breedlove coll., 21 Oct 1981 (CAS
029679). In hills on E side of San Cristébal de las Casas, elev.
7400 ft (2255 m), D. E. Breedlove coll., 22 Aug 1981 (CAS
029680). Aguacutenango, elev. 5900 ft (1798 m), pine-oak for-
est, D. E. Breedlove coll., 12 Jun 1966 (CAS 037059). Rancho
Nuevo, 8.6 mi SW of San Cristobal de las Casas, elev. 7800 ft
(2377 m), pine forest, L. Baptista coll., 19 Aug 1966 (CAS
037066). Near San Cristébal de las Casas, elev. 7000 ft (2134
m), E. Hunn coll., 15 Nov 1971 (CAS 037065). At km 1156 on
Highway 190 between Chiapa del Corzo and San Cristobal de
las Casas, elev. 7750 ft (2362 m), pine-oak forest, L. Baptista
coll., 18 Aug 1966 (CAS 037062). Seventeen kilometers SE of
San Cristobal de las Casas, pine-oak forest, elev. 2195 m, D. E.
Breedlove & K. E. Lucas coll., 15 Jan 1973 (CAS 037061).
Along small stream on Cerro Tres Picos, elev. 7000 ft (2134 m),
D. E. Breedlove coll., 28 Mar 1973 (CAS 037060). Two to four
kilometers SW of Highway 190 along road to San Lucas Za-
potal, elev. 7500 ft (2286 m), D. E. Breedlove coll., 8 Sep 1974
(CAS 037064). Ten and one half miles SW of San Cristébal de
las Casas, K. E. Lucas coll., 2 Sep 1972 (CAS unnumbered).
SE side of Cerro Tres Picos, montane rain forest, elev. 6000 ft
(1828 m), D. E. Breedlove coll., 28 May 1972 (CAS unnum-
bered). E side of Cerro Bola just E of Tres Picos, elev. 6000 ft
(1828 m), D. E. Breedlove coll., 4 May 1972 (CAS unnum-
bered). Near San Cristébal, E. Hunn coll., 1971 (CAS unnum-
bered). Laguna Chamula, microwave tower between Comitan
and Amantenango, elev. 8300 ft (2530 m), 20 Aug 1972 (CAS
unnumbered). Zinacantan, elev. 2000 m (BEQUAERT, 1957). En-
virons of Chiapa (FISCHER & CRossE, 1870-1902). Rancho
Nuevo, 8 mi from Las Casas (BEQUAERT, 1957). Mountain above
the Sumidero near Las Casas (BEQUAERT, 1957).

Guatemala: Mountains of Alta Vera Paz (FISCHER & CROSSE,
1870-1902). Coban (FISCHER & CROSSE, 1870-1902; MARTENS,
1890-1901). Purula, towards the head of the Polochic valley
(MARTENS, 1890-1901). Cerro Zunil, on the Pacific slope, near

The Veliger, Vol. 275 NoZ

Page 218

Quetzaltenango (7bid.). Hacienda Buenavista in Upper Chol- MarTENS, 1890-1901). Duena (FISCHER & Crosse, 1870-1902).

huitz, elev. 4000-5000 ft (1219-1524 m), in forests (zbid.). Dep- Honduras: Cordillera of San Marcos, elev. about 2660 m
(FISCHER & Crosse, 1870-1902; MARTENS, 1890-1901).

to. Solola, Toliman, in the hills above San Lucas, near the lake

of Atitlan, temperate zone (FISCHER & CRossE, 1870-1902; El Salvador: Volcan de Santa Ana (BEQUAERT, 1957).

The Veliger 27(2):219-226 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

The Genera Moelleria Jeffreys, 1865, and

Spiromoelleria gen. nov. in the North Pacific, with

Description of a New Species of Spzromoelleria

(Gastropoda: Turbinidae)

RAE BAXTER

Box 96, Bethel, Alaska 99559

JAMES H. McLEAN

Los Angeles County Museum of Natural History,
Los Angeles, California 90007

Abstract. ‘Two genera of minute turbinid gastropods in the subfamily Homalopomatinae, Moelleria
Jeffreys, 1865, and Spiromoelleria gen. nov., are here called the Moelleria group. These genera differ
from other homalopomatine genera in having a calcareous operculum with a multispiral pattern on its
exterior surface, having the operculum unable to retract deeper than flush with the apertural margin,
and lacking the apertural denticle of Homalopoma and related genera. Moelleria is monotypic for M.
costulata (Mller, 1842), which has a circumboreal, offshore distribution. It has coalescing axial sculp-
ture of a kind unknown in other living trochacean genera. Spiral sculpture is characteristic of only two
shallow-water North Pacific species in the new genus Spiromoelleria: S. quadrae (Dall, 1897), the
type species, and S. kachemakensis spec. nov. Moelleria drusiana Dall, 1919, is synonymized with S.
quadrae. The three species are sympatric in the Gulf of Alaska.

INTRODUCTION

Two SPECIES until now assigned to Moelleria Jeffreys,
1865, have major differences in sculpture, although these
differences have not previously been thought to merit ge-
neric distinction. The discovery of a third, new species,
conforming to one of the sculptural types, indicates that
the two basic kinds of sculpture should be distinguished
at the generic level. We, therefore, propose the new genus
Spiromoelleria, which now includes two species; Moel-
leria remains monotypic.

The two genera differ in shell and opercular characters
from genera related to Homalopoma Carpenter, 1864, at
a level that will be treated as a tribe in a review of tro-
chacean classification (McLean & Hickman, in prepara-
tion). In this paper we discuss these distinctions but refer
to the two genera as the Moelleria group. The new genus

and species have already been included in a checklist of
the mollusks of Alaska (BAXTER, 1983); they are first
validated here.

Collections examined include those of Rae Baxter (RB),
the University of Alaska, Fairbanks (UAF), the Califor-
nia Academy of Sciences, San Francisco (CAS), the Los
Angeles County Museum of Natural History (LACM),
and the National Museum of Natural History, Washing-
ton, D.C. (USNM). Voucher specimens of Moelleria cos-
tulata, Spiromoelleria quadrae, and Homalopoma lacuna-
tum, and paratypes of S. kachemakensis, have been
deposited in these institutions and in the National Mu-
seum of Canada (NMC).

Shells are illustrated by macrophotography and scan-
ning electron microscopy (SEM). Radulae of two species
are illustrated with SEM. Living specimens of S. kache-
makensis were sketched by Baxter under a dissecting mi-

Page 220

Figure 1

Spiromoelleria kachemakensis Baxter & McLean, spec. nov.
Drawings of living specimen (by Baxter). A. Ventral view of
head, foot, and epipodial structures, showing cephalic tentacles
with eyes at base, mouth, foot (anterior tip broad with papillate
edge), four pairs of epipodial tentacles, and neck lobes posterior
to eyes; B. Enlarged view of cephalic (or epipodial) tentacle,
showing papillae.

croscope. Shells were measured with calibration scales for
a dissecting microscope.

Family TURBINIDAE
Subfamily HOMALOPOMATINAE
The Moelleria Group of Genera

Moelleria Jeffreys, 1865, and Spiromoelleria gen. nov.
have the following shared features:

Shell minute (under 4 mm maximum dimension), de-
pressed, deeply umbilicate; aperture nearly circular, only
slightly oblique; columellar denticles lacking; lip not
thickened. Sculpture of axial and spiral elements, or spiral
elements alone. Interior nacreous layer thin. Protoconch
with pointed tip, as in most trochaceans. Operculum not
retractable deeper than apertural margin; interior surface
of operculum flat, multispiral; exterior surface concave,
also multispiral. Cephalic lappets lacking; left and right
neck lobes simple; left and right epipodial ridge with four
pairs of papillate epipodial tentacles; anterior end of foot
with lateral tips. Rachidian tooth narrow at tip and base,
broad at midpoint; lateral teeth 5, broad at midpoint and
overlapping adjacent laterals; lateromarginal plate at-
tached to base of first marginal; marginal teeth numerous,
cusped.

The thin shell, thin nacreous layer, and lack of colu-
mellar denticles in the Moelleria group are characteristic.
Genera related to Homalopoma Carpenter, 1864, differ in
having thicker shells, a more pronounced nacreous layer,
and the outer lip thickened in mature specimens.

The Veliger, Vol. 27, No. 2

The operculum in the Moelleria group is multispiral on
both surfaces and unable to retract deeper than flush with
the apertural margin. Opercula in genera related to Hom-
alopoma differ in having a paucispiral pattern on the in-
terior surface and the exterior surface thickened by cal-
careous deposition close to the columellar wall, which
obliterates the pattern of coiling; these opercula are ca-
pable of retracting well within the aperture.

Based on preserved specimens, FRETTER & GRAHAM
(1977:93) reported for Moelleria costulata: ““The snout is
broad and depressed, the closed mouth a vertical slit at its
end bordered by rather fleshy lips not split or extended
mid-ventrally. The tip of the snout is not bilobed but
carries a slightly scalloped edge. The tentacles are setose
and are flanked laterally by eye stalks each carrying a
large black eye at its tip. There are no cephalic lappets.
The foot is rather straight anteriorly, its corners elongat-
ed, and tapers to a narrow posterior end. A neck lobe lies
on each side, smooth-edged, unconnected to the cephalic
tentacles but joined to an epipodial fold, carrying (?) 4
tentacles similar to the cephalic ones.” The “setae” of
Fretter & Graham are equivalent to the “papillae” of
Crisp (1981), whose terminology we adopt here.

The living animal of Spiromoelleria kachemakensis
(Figure 1) is similar to Moelleria costulata, as described
by FRETTER & GRAHAM (1977). In dorsal view of the
extended animal, only the outer portion of the cephalic
tentacles and the tips of the first pair of epipodial tentacles
show past the shell edge. The short foot is expanded an-
teriorly and bluntly pointed posteriorly; its anterior mar-
gin is finely papillate, the rest of the margin smooth. The
cephalic tentacles project about 40% of shell diameter, are
papillate, with the pointed, cone-shaped papillae directed
anteriorly. The length of the papillae is equal to the di-
ameter of the tentacles near their blunt tips. Along the
epipodial fold there are four pairs of elongate, round, blunt-
tipped epipodial tentacles, which are papillate like the
cephalic tentacles. First epipodial tentacle more than twice
the length of the second, the posterior the shortest; their
diameter about the same as the cephalic tentacles. Eye
spots are black; the eyes are on short stalks, lateral to the
cephalic tentacles and are attached to them for about half
their length. There are two pairs of neck lobes, which are
short, smooth, and triangular in shape. The snout tip is
circular, with a rounded central mouth. The operculum
on the expanded animal appears to block the umbilical
opening. The animal of S. quadrae has the posterior region
of the foot with fine, short, triangulate papillae, differing
from the other species in having the papillae of the ten-
tacles much finer and more numerous.

External anatomical characters are similar to those of
Homalopoma and related genera (McLean & Hickman,
in preparation), which suggests that the Moelleria group
should be retained in the Homalopomatinae.

Radular ribbons of four specimens of Moelleria costulata
examined by Baxter had 35 to 44 rows of teeth and 47 to

R. Baxter and J. H. McLean, 1984

Page 221

Explanation of Figures 2 and 3

Figure 2. Moelleria costulata (Mller, 1842). Radular ribbon.
LACM 73-23, 9 m off Hesketh Island, Kachemak Bay, Cook
Inlet, Alaska. Bar = 40 um.

54 pairs of marginal teeth. In 12 specimens of Spiromoel-
leria quadrae, there were 46 to 61 rows of teeth and mar-
ginal tooth counts of 56 to 78 pairs. For 13 specimens of
S. kachemakensis, there were 37 to 64 rows of teeth and
43 to 73 pairs of marginal teeth.

Radulae of Moelleria costulata (Figure 2) and Spiro-
moelleria quadrae (Figure 3) are illustrated here. SEM
illustrations of the radula of S. kachemakensis were not
made, but the breadth of the rachidian tooth under the
light microscope is comparable to that of M. costulata (Fig-
ure 2). The rachidian appears to be much less developed
in M. costulata than in S. quadrae, but Hickman notes
(personal communication) that failure of a shaft and cusp
to develop fully is not unusual in many genera and may
be characteristic of an entire species or sometimes only of
some individuals. The morphology of the lateral and mar-
ginal teeth is similar in the two species. In both species,
the first marginal is expanded at the base, representing a
fusion of the first marginal with the lateromarginal plate.
The particular form of the lateromarginal plate in these
genera will be discussed in more detail elsewhere by Hick-
man.

Genus Moelleria Jeffreys, 1865

Moelleria JEFFREYS, 1865:292 [as Molleria]. Type species by
original designation: Margarita costulata Méller, 1842.

The generic and specific descriptions are combined un-
der the species heading, as this genus is monotypic.

A monotypic genus is recognized on the basis of the
unique shell sculpture—in which the axial ridges coalesce.
Other trochaceans generally have collabral axial ribs, in
which a complete rib is produced along the lip edge.

The original spelling Molleria is correctly emended to
Moelleria.

Moelleria costulata has a circumboreal distribution and

Figure 3. Spiromoelleria quadrae (Dall, 1897). Radular rib-
bon. LACM 73-22, intertidal, Yukon Island, Kachemak Bay,
Cook Inlet, Alaska. Bar = 40 um.

is well known, having been most recently discussed by
FRETTER & GRAHAM (1977:93).

Moelleria costulata (Moller, 1842)
(Figures 2, 4)

Margarita costulata MOLLER, 1842:81.

Adeorbis costulata: STIMPSON, 1851:32; GOULD, 1870:278,
fig. 538.

Cyclostrema (Margarita) costulata: MORCH, 1857:10.

Molleria costulata: JEFFREYS, 1865:291; DAUTZENBERG &
FISCHER, 1912:261; THIELE, 1929:65; FRETTER &
GRAHAM, 1977:93, figs. 71 (drawing of shell), 72 (SEM
view of shell and protoconch).

Molleria costulata: SARS, 1878:127, pl. 9, figs. 8a—c (shell),
pl. Ill, figs. 5a—b (radula); BROGGER, 1901: pl. 12, figs.
4a-c.

Molleria costulata: MACGINITIE, 1959:1, pl. 3, figs. 2-5.

Moelleria costulata. ODHNER, 1912:19, pl. 5, figs. 43-47;
ODHNER, 1915:152; THORSON, 1941:23; CLARKE, 1962:
13; MacPHERSON, 1971:29, pl. 2, fig. 5; ABBOTT, 1974:
61, fig. 501; WAREN, 1980: pl. 11, fig. 1 (caption only);
BAXTER, 1983:28.

Margarita minutissrma MIGHELS, 1843:349, pl. 16, fig. 5;
JOHNSON, 1949:227 (listed only); MACPHERSON, 1971:
29 (as probable synonym of M. costulata).

Margarites (Margarites) minutissimus: ABBOTT, 1974:37 (listed
as valid species).

Description: Shell minute, turbinate, deeply umbilicate;
aperture and whorls circular; peritreme complete; suture
deeply impressed. Whorls 3; sculpture of strong, flat-
topped, slightly sigmoid axial ridges, some bifurcating be-
low periphery; interspaces flat-bottomed, variable in width;
spiral cords 0 to 9 (on Alaskan specimens), on base and
umbilical wall only, variable in strength and spacing,
forming nodes on crossing axial ribs. Surface dull, color
uniformly brown, tan or gray. Operculum calcareous, ex-
terior surface concave, with up to 6 evenly expanding

Page 222

The Veliger, Vol. 27, No. 2

Explanation of Figures 4 to 6

Figure 4. Moelleria costulata (MGller, 1842). Three views of same
specimen. LACM 73-23, 9 m off Hesketh Island, Kachemak
Bay, Cook Inlet, Alaska. Height 2.04 mm, diameter 2.34 mm.

Figure 5. Spiromoelleria quadrae (Dall, 1897). Three views of
same specimen. LACM 73-22, intertidal, Yukon Island, Ka-

volutions in multispiral pattern; interior surface flat, with
same multispiral pattern.

Dimensions: Illustrated specimen (Figure 4): height 2.04
mm, diameter 2.34 mm. Shell height 87% of diameter.

Type material and type localities: Moelleria costulata,
type not searched, type locality: Greenland (MOLLER,
1842). Margarita minutissima, type not mentioned by

JOHNSON (1949), presumably destroyed in the 1854 fire -

at Portland Society of Natural History; type locality: Cas-
co Bay, Maine (MIGHELS, 1843).

chemak Bay, Cook Inlet, Alaska. Height 1.68 mm, diameter 2.46
mm.

Figure 6. Spiromoelleria kachemakensis spec. nov. Three views
of holotype. LACM 1989, 9 m off Hesketh Island, Kachemak
Bay, Cook Inlet, Alaska. Height 1.82 mm, diameter 2.24 mm.

Distribution: Circumboreal in the Arctic Ocean
(MACGINITIE, 1959; MACPHERSON, 1971; ODHNER,
1912). Alaskan distribution from Attu, Aleutian Islands
(LACM) (52°49'N, 172°10’E), to Turner Bay, Taku In-
let, southeastern Alaska (UAF) (58°19’N, 133°59'W). At-
lantic distribution south to Maine, Greenland, Iceland,
and Morocco (THORSON, 1941).

Habitat: On mud-gravel or mud-shell bottoms, 5 to 1943
m, occasionally common. Living specimens were reported
off Point Barrow, Alaska, as deep as 200 m (MACGINITIE,
1959). THORSON (1941) reported a depth of 1943 m off

R. Baxter and J. H. McLean, 1984

Morocco. There are, however, no records from such depths
in Alaska. Living specimens of Moelleria costulata oc-
curred with the type lot of Spiromoelleria kachemaken-
sis in Kachemak Bay, Cook Inlet, Alaska.

Remarks: MACGINITIE (1959) detailed the extensive shell
variation for this species occurring off Point Barrow,
Alaska. Specimens from the Gulf of Alaska often lose the
axial sculpture on the final whorl. The number of basal
cords varies from 0 to 9.

ABBOTT (1974) listed Margarites minutissisma Mighels
as a good species. However, judging from the original
illustration, it may clearly be assigned to the synonymy of
Moelleria costulata, as suggested by MACPHERSON (1971).

Genus Spiromoelleria gen. nov.
Type species: Moelleria quadrae Dall, 1897. Alaska.

Description: Shell umbilicate; whorl circular in cross sec-
tion; suture deeply impressed. Sculpture of regular spiral
cords on entire body whorl and evenly rounded base; axial
sculpture lacking. Calcareous operculum multispiral on
both sides, not retractable deeper than aperture.

Spiromoelleria differs from Moelleria in lacking wavy
axial sculpture. That there are two species is a strong
point in support of the need for generic separation from
Moelleria.

The two species of Spiromoelleria differ in shell pro-
portions and in the strength of spiral sculpture. The dis-
tribution of this genus is limited to the northern Pacific.

Spiromoelleria quadrae (Dall, 1897)
(Figures 5, 7, 8)

“Molleria quadrae Dall”: NEwcoms, 1896:19 [nomen nu-
dum].

Molleria quadrae DALL, 1897:15, pl. 1, figs. 14, 14a; WIL-
LETT, 1919:26; DALL, 1921:174; OLDROYD, 1924:170,
pl. 44, figs. 7, 8.

Molleria quadrae: OLDROYD, 1927:171, pl. 91, figs. 11, 11a;
KEEN, 1937:41; LAROCQUE, 1953:135.

Moelleria quadrae: BURCH, 1946:26; EYERDAM, 1960:93;
BERNARD, 1970:79; ABBOTT, 1974:61; GOLIKOV &
GULBIN, 1978:183.

Moelleria (Spiromoelleria) quadrae: BAXTER, 1983:28.

Molleria drusiana DALL, 1919:358; OLDROYD, 1927:172;
KEEN, 1937:41; LAROcQUE, 1953:135.

Molleria drusiana: DALL, 1921:174.

Moelleria drusiana: BURCH, 1946:26; EYERDAM, 1960:93;
ABBOTT, 1974:61.

Description: Shell minute, depressed turbinate, broadly
umbilicate; aperture and whorls circular, peritreme com-
plete, suture deeply impressed, lip thin. Whorls 3.5; axial
sculpture of weak, irregular growth increments only; spi-
ral sculpture of variable number (49-77) of fine, narrow
cords; spiral cords present throughout, from suture to um-
bilical walls, stronger on base, with wider interspaces on
base. Color tan or whitish, rarely stained with rust. Oper-

Page 223

culum calcareous, outer surface concave, with up to 6
evenly expanding volutions in multispiral pattern.

Dimensions: Illustrated specimen (Figure 5): height 1.68
mm, diameter 2.46 mm. Shell height 68% of diameter.

Distribution and habitat: North Pacific Ocean: Kuril
Islands (GOLIKOV & GULBIN, 1978); Aleutian Islands
(LACM: Attu, Amchitka); Kodiak Island (LACM); Ka-
chemak Bay, Cook Inlet (RB, LACM); Prince William
Sound (RB), Southeastern Alaska (WILLETT, 1919);
Cumshewa Inlet, British Columbia (type locality). On
undersides of rocks at low tide, on gravel or muddy, shell
bottoms to 30 m. Common in intertidal zone in Kachemak
Bay, Cook Inlet, Alaska; more frequent in the subtidal
zone in southeastern Alaska. GOLIKOV & GULBIN (1978)
reported it at 20 m, Simushir Island, Kuril Islands (ap-
proximately 47°N, 152°E).

Type material and type localities: Moelleria quadrae:
USNM 107411, 18-27 m, Cumshewa Inlet, Queen Char-
lotte Islands, British Columbia (approximately 53°N,
132°W)); collected by C. F. Newcombe. Moelleria drusiana:
USNM 31117, intertidal, Constantine Harbor, Amchitka
Island, Aleutian Islands, Alaska; collected by W. H. Dall.

Remarks: Although DALL (1919) reported that Moelleria
drusiana has the “‘surface smooth except for microscopic
incremental lines,” there are 42 fine spiral striae on the
final whorl of the holotype. The holotype is clearly an
immature specimen of M. quadrae, 1.1 mm in height and
1.5 mm in diameter.

Spiromoelleria kachemakensis
Baxter & McLean, spec. nov.

(Figures 1, 6, 9, 10)

Moelleria (Spiromoelleria) kachemakensis: BAXTER, 1983:28
[nomen nudum].

Description: Shell minute, turbinate, deeply umbilicate,
aperture and whorls circular, peritreme complete, suture
deeply impressed, lip thin. Whorls 3.4 to 3.7; axial sculp-
ture of irregular growth increments only; spiral sculpture
of 35-53 flat-topped cords on final whorl; spiral cords
increasing in number by emergence between existing ribs;
ribs faint near suture, strong and with narrow interspaces
on upper surface of body whorl, with broader interspaces
on lower surface. Color white to light tan, surface often
stained rust to black. Operculum calcareous, multispiral,
outer surface concave, with 6 evenly expanding volutions,
not retracting within aperture.

Dimensions: Holotype: height 1.82 mm, diameter 2.24
mm; height 81% of diameter.

Type material: 12 live-collected specimens from the type
locality, dredged by Baxter & McLean, 2 August 1973.
Holotype LACM 1989; 5 paratypes LACM 1990, 2

Page 224

The Veliger, Vol. 27, No: 2

Explanation of Figures 7 to 10

Figure 7. Spiromoelleria quadrae (Dall, 1897). Dorsal view,
SEM. LACM 103331a, intertidal, Jakalof Bay, Kachemak Bay,
Cook Inlet, Alaska. Height 1.48 mm, diameter 2.20 mm.

Figure 8. Spiromoelleria quadrae (Dall, 1897). Basal view, SEM.
LACM 103331b, as same locality as Figure 7. Specimen sub-
sequently lost.

paratypes CAS 029766, 2 paratypes USNM 804405, 2
paratypes NMC 86526, 1 paratype RB B461-12.

Type locality: 9 m on mud-shell bottom, off northwest
side Hesketh Island, Kachemak Bay, Cook Inlet, Alaska
(59°30'31”N, 151°30'01”W). The name of the species is
based on the type locality.

Distribution: Kachemak Bay, Cook Inlet; along the Ke-
nai Peninsula; Prince William Sound; east to Rush Bay,
Glacier Bay, southeastern Alaska (58°28'’N, 136°04’W)
(UAF M2671, collected by George Mueller). Not col-
lected at Kodiak Island or to the west. Living specimens
have been collected by Baxter at or near the type locality
and at Port Dick on the south side of the Kenai Peninsula
(59°13’N, 151°03’W). Living on undersides of rocks at

Figure 9. Spiromoelleria kachemakensis spec. nov. Dorsal view,
SEM. LACM 103332a, same locality as Figure 7. Height 1.80
mm, diameter 2.18 mm.

Figure 10. Spiromoelleria kachemakensis spec. nov. Basal view,
SEM. LACM 103332b, same locality as Figure 7. Height 1.68
mm, diameter 2.06 mm.

low tide to 45 m on gravel or muddy, shell bottoms, par-
ticularly at the base of vertical drop-offs.

Remarks: Spiromoelleria kachemakensis has a higher
spire (shell height 81% of diameter, compared to 68%), a
narrower umbilicus, and more prominent spiral cords than
S. quadrae. There are no intergrading specimens.

The small turbinid Homalopoma lacunatum (Carpenter,
1864), which occurs from Alaska to Washington, differs
in having a larger, thicker shell, a less impressed suture
and opercular volutions that are paucispiral.

We have no records of the three species occurring at
the same station, as Spiromoelleria quadrae has been tak-
en only intertidally and Moelleria costulata only subtidally
in Kachemak Bay. However, S. quadrae and S. kache-
makensis were collected together at low tide (near the type

R. Baxter and J. H. McLean, 1984

locality of S. kachemakensis) at the west end of Yukon
Island, Kachemak Bay (59°31.5'N, 151°29.5'W) by Bax-
ter & McLean in August 1973. Living specimens of M.
costulata were collected offshore with S. kachemakensis at
the type locality.

MAcNEIL et al. (1943) illustrated an eroded fossil spec-
imen of Spiromoelleria from a raised terrace at Nome,
Alaska, which they identified as “Molleria n. sp.?” Al-
though its proportions are similar to those of S. kache-
makensis, the specimen (USNM 499052) is much larger
(dimensions: height 2.96 mm, diameter 3.40 mm) than
known for S. kachemakensis. In size it is comparable to
Homalopoma lacunatum, but it has the deeply impressed
suture of the genus Spiromoelleria. We refrain from fur-
ther treating this specimen in the absence of more and
better preserved material.

ACKNOWLEDGMENTS

Collectors who have contributed to the distributional in-
formation recorded here include David Lindberg, George
Mueller, Charles O’Claire, Paul Scott, and the late Rob-
ert Talmadge. We thank Joseph Rosewater (USNM) and
Barry Roth (CAS) for access to collections. SEM photos
of radulae were generously provided by Carole S. Hick-
man. Photographs of shells are the work of Bertram C.
Draper. Paul Greenhall and Cynthia Gust (USNM) pro-
vided the SEM views of shells. We thank Eugene Coan
and Carole Hickman for reading the manuscript and of-
fering helpful suggestions.

LITERATURE CITED

ABBOTT, R. T. 1974. American seashells. 2nd ed. Van Nos-
trand Reinhold: New York. 663 pp., 24 pls.

BAXTER, R. 1983. Mollusks of Alaska. Baxter: Bethel, Alaska.
xiv + 69 pp.

BERNARD, F.R. 1970. A distributional check list of the marine
Mollusca of British Columbia: based on faunistic surveys
since 1950. Syesis 3:75-94.

BROGGER, W. C. 1901. Om de Senglaciale og Postglaciale
Nivaforandringer i Kristianiafeltet (Molluskfaunan). Norges
Geol. Undersog., no. 31:731 pp., 19 pls.

Burcu, J. Q. (ed.). 1946. Distributional list of the West
American marine mollusks from San Diego, California, to
the Polar Sea. Minutes Conchol. Club of Southern Calif.,
no. 57:40 pp.

CxiaRKE, A. H., JR. 1962. Annotated list and bibliography of
the abyssal marine mollusks of the world. Natl. Mus. Can-
ada, Bull. 181:114 pp.

Crisp, M. 1981. Epithelial structures of trochids. J. Mar. Biol.
Assoc. U.K. 61:95-106.

DaLL, W. H. 1897. Notice of some new or interesting species
of shells from British Columbia and the adjacent region.
Nat. Hist. Soc. Brit. Col., Bull. 2:1-18, pls. 1-2.

DaLL, W. H. 1919. Descriptions of new species of Mollusca
from the North Pacific Ocean in the collection of the U.S.
National Museum. Proc. U.S. Natl. Mus. 56(2295):293-
371.

Da.tL, W. H. 1921. Summary of the marine shellbearing mol-
lusks of the northwest coast of America, from San Diego,

Page 225

California, to the Polar Sea, mostly contained in the collec-
tion of the United States National Museum, with illustra-
tions of hitherto unfigured species. U.S. Natl. Mus., Bull.
112:217 pp., pls. 1-22.

DAUTZENBERG, P. H. & H. FISCHER. 1912. Mollusques pro-
venant des campagnes de |’Hirondelle et de la Princesse-
Alice dans les Mers du Nord. Resultats des campagnes sci-
entifiques accomplies sur son yacht par Albert ler Prince
Souverain de Monaco. Monaco. 629 pp., 11 pls.

EYERDAM, W. J. 1960. Mollusks and brachiopods from Af-
ognak and Sitkalidak Islands, Kodiak Group, Alaska. Nau-
tilus 74(2):91-95.

FRETTER, V. & A. GRAHAM. 1977. The prosobranch molluscs
of Britain and Denmark. Part 2. Trochacea. J. Moll. Stud.,
Suppl. 3:39-100.

Go.ikov, A. N. & V. V. GULBIN. 1978. Prosobranchial gas-
tropods of the Kurile Islands. I. Orders Docoglossa—Ento-
mostoma. Pp. 159-223. In: O. G. Kussakin (ed.), Fauna
and vegetation of the shelf of the Kurile Islands. Nauka:
Moscow.

GouLpD, A. A. 1870. Report on the Invertebrata of Massa-
chussetts. Second edition, comprising the Mollusca. Edited
by W. G. Binney. Wright and Potter: Boston. 524 pp., 27
pls.

JEFFREYS, J. G. 1865. British conchology. Vol. 3. John van
Voorst: London. 393 pp., 8 pls.

JOHNSON, R. I. 1949. Jesse Wedgwood Mighels with a bib-
liography and catalogue of his species. Occasional Papers
on Mollusks, Museum of Comparative Zoology, Harvard
1(14):213-231.

Keen, A. M. 1937. An abridged check list and bibliography
of west North American marine mollusks. Stanford Uni-
versity Press: Stanford, Calif. 84 pp.

LARocquE, A. 1953. Catalogue of the Recent Mollusca of
Canada. Natl. Mus. Canada, Bull. 129:406 pp.

MacGiniTig£, N. 1959. Marine Mollusca of Point Barrow,
Alaska. Proc. U.S. Natl. Mus. 109(4312):59-208, pls. 1-
Dil

MacNEIL, F. S., J. B. MERTIE, JR. & H. A. Pivssry. 1943.
Marine invertebrate faunas of the buried beaches near Nome,
Alaska. J. Paleont. 27(1):69-96, pls. 10-16.

MacPHERSON, E. 1971. The marine molluscs of Arctic Can-
ada. Prosobranch gastropods, chitons, and scaphopods. Natl.
Mus. Canada, Publs. Biol. Ocean., no. 3:149 pp., 7 pls.

MIGHELS, J. W. 1843. Descriptions of six species of shells
regarded as new. Boston J. Natur. Hist. 4:345-350, pl. 16.

MOLLER, H. P. C. 1842. Index molluscorum Groenlandia.
Naturhist. Tidsskrift, ser. 1, 4(1):76-97.

Morcu, O. A. L. 1857. Fortegnelse over Gronlands Bloddyr.
Tilloeg. nr. 4. Pp. 75-100. Jn: Rink, Grenland geographisk
og statistisk beskrivet af Rink. Copenhagen.

Newcoms, C. F. 1896. Some new or rare species of marine
Mollusca recently found in British Columbia. Nautilus 10(2):
16-20.

ODHNER, N. H. 1912. Northern and Arctic invertebrates in
the collections of the Swedish State Museum. V. Proso-
branchia. Kungl. Svensk. Vet. Ak. Handl. 50(5):1-93, pls.
1-7.

ODHNER, N. H. 1915. Die Molluskenfauna des Eisfjordes.
Zoologische Ergebnisse der Schwedischen Expedition nach
Spitzbergen 1908 unter Leitung von G. De Geer. Stockholm
Vet.-Ak. Handl. 54:274 pp., 13 pls.

OpRoyD, I. S. 1924. Marine shells of Puget Sound and vi-
cinity. Stanford University Press: Stanford. 271 pp., 49 pls.

Ouproyp, I. S. 1927. The marine shells of the west coast of

Page 226

The Veliger, Volz 27-3NoyZ

North America. Vol. 2, part 3. Stanford Univ. Publ., Univ.
Series, Geol. Sci.:339 pp., pls. 73-108.

Sars, G. O. 1878. Bidrag til Kundskaben om Norges Arktiske
Fauna. I. Mollusca regionis Arcticae Norwegiae. Christi-
ania. 466 pp., 34 + XVIII pls.

Stimpson, W. 1851. Shells of New England. A revision of the
synonymy of the testaceous mollusks of New England, with
notes on their structure, and their geographical and bathy-
metrical distribution. Boston. 58 pp., 2 pls.

THIELE, J. 1929. Handbuch der systematischen Weichtier-

kunde. Erster Teil, Loricata, Gastropoda. I. Prosobranchia
(Vorderkiemer). Gustav Fischer: Jena. 376 pp.

THORSON, G. 1941. Marine Gastropoda Prosobranchiata. The
zoology of Iceland. Copenhagen. Vol. 4, part 60, 150 pp.

Waren, A. 1980. Marine Mollusca described by John Gwyn
Jeffreys, with the location of the type material. Conch. Soc.
Great Britain & Ireland, Spec. Publ. 1:60 pp., 6 pls.

WILLETT, G. 1919. Mollusca of Forrester Island, Alaska.
Nautilus 33(1):21-28.

THE VELIGER
© CMS, Inc., 1984

The Veliger 27(2):227-237 (October 5, 1984)

The Bernardinidae of the Eastern Pacific
(Mollusca: Bivalvia)
by

EUGENE COAN

Research Associate, Department of Invertebrate Biology,
California Academy of Sciences, Golden Gate Park,
San Francisco, California 94118

Abstract. ‘The Bernardinidae is a family of minute, shallow-water marine bivalves as yet known
only from the eastern Pacific. They combine an internal ligament with three cardinal teeth in the left
valve, two or three in the right, and at least one lateral tooth. The four known species brood their
young. The family is here assigned to the Cyamiacea instead of where it has been placed in the
Arcticacea.

In Bernardina, the anterior end is longer than the posterior; there is heavy concentric sculpture; and
there is a large anterior lateral tooth, but no posterior lateral. Bernardina bakeri Dall, the type species,
occurs from Pacific Grove, California, to Isla Natividad, Baja California Sur. Bernardina margarita
(Carpenter) occurs from Isla Guadalupe, Baja California Norte, to Bahia Banderas, Jalisco, Mexico.

In Halodakra, the posterior end is longer than the anterior; the sculpture consists of fine concentric
threads; and there is a posterior lateral tooth. Halodakra, s.s., lacks an anterior lateral tooth. Halodakra
(H.) subtrigona (Carpenter), the type species, occurs from Tomales Bay, California, to Mancora,
Peru. A new subgenus, Stohleria, is proposed for H. (S.) salmonea (Carpenter), which has an anterior
lateral tooth. This species occurs from Brookings, Oregon, to Punta San Hipolito, Baja California Sur;

Crassatella marginata Keep and Psephidia brunnea Dall are synonyms.

INTRODUCTION

I BECAME curious about the Bernardinidae when, during
my review of the Crassatellinae of the eastern Pacific
(Coan, 1984), I attempted to find a proper home for Cras-
satella marginata Keep, 1887. I concluded then and con-
firm now that it is a synonym of Halodakra salmonea (Car-
penter, 1864). In arriving at this conclusion, however, I
discovered that the two previously described species of
Halodakra Olsson, 1961, are sympatric along much of the
coast of southern California and Baja California Norte.
Here I explain how they can be separated. I also provide
characters differentiating the two species of Bernardina
Dall, 1910. The distributions of all four species are doc-
umented, a neotype and four lectotypes are designated,
and all four species are illustrated. The placement of the
family within bivalves is also discussed.

CONVENTIONS anp ABBREVIATIONS

In the following treatment, each valid taxon is followed
by a synonymy, information on type specimens and local-

ities, notes on distribution and habitat, and additional dis-
cussion.

The synonymies include all major accounts of the species,
but generally not minor mentions in the literature. The
entires are arranged in chronological order under each
species-name, with changes in generic allocation from the
previous entry, if any, and other notes provided in brack-
ets after each entry.

The following are the abbreviations of institutions used
in the text:

AHF—Allan Hancock Foundation, Los Angeles

BM(NH)—British Museum (Natural History), London

CASIZ—California Academy of Sciences, Department of
Invertebrate Zoology, San Francisco

LACM—Los Angeles County Museum of Natural His-
tory

USNM—United States National Museum of Natural
History Washington, D.C.

The thicknesses are of entire specimens with valves ar-
ticulated unless stated otherwise. The proportions are based

Page 228

The Veliger, Vol. 27, No. 2

on measurement of at least 10 specimens. A “pair” means
the two valves of a single specimen.

Superfamily CYAMIACEA
Family BERNARDINIDAE Keen, 1963
Bernardinidae KEEN, 1963:91

The family Bernardinidae was proposed by KEEN (1963)
for the eastern Pacific genera Bernardina and Halodakra.
Later (KEEN, 1969:N650), she supplied a definition of the
family.'

The shells of species in this family are small to minute,
attaining only about 4.5 mm in length. Sculpture consists
of concentric threads or prominent concentric ribs. The
hinge has an oblique resilium, well below the dorsal mar-
gin, in combination with two or three cardinal teeth in
each valve and at least one lateral tooth. The pallial line
is broad and entire. There is no evident lunule or escutch-
eon.

All four known species of the Bernardinidae occur in
the eastern Pacific among rubble in rocky areas, from the
intertidal area to subtidal depths; none has been recorded
deeper than 60 m. All brood their young; I have observed
broods in dried specimens of each of the four species.

This family has been placed in the Arcticacea, members
of which attain 50 to 100 mm in size, have an external
ligament, and are not known to brood their young. I think
a better placement would be in the Cyamiacea, which was
most recently studied by PONDER (1971). Many members
of this superfamily are small, have an internal ligament,
and brood their young within their ctenidia. Among other
known differences between these two superfamilies are the
morphologies of the ctenidia. The Arcticacea have plicate
ctenidia with interlamellar septa (Boss, 1982:1146); those
of the Cyamiacea lack interlamellar septa and are not
plicate (Boss, 1982:1133).

Although most bernardinids are evidently not uncom-
mon in shallow water, no preserved material is yet avail-
able for study. Observations on living or preserved spec-
imens would considerably increase our knowledge about
this family, including its taxonomic placement.

The two bernardinid genera are reminiscent of some
species of the Veneridae in which the ligament may be
somewhat sunken below the hinge margin and which brood
their young. Frank BERNARD (1982:147) has recently pro-
posed the genus Nutricola for one such venerid. Bernar-
dinids can be distinguished from these small venerids by
their lack of a pallial sinus, their proportionately less con-
spicuous beaks, and their’ internal ligament. Bernardina
with its long anterior end is unlikely to be confused with
other genera. Halodakra is most likely to be confused with

' The family name is based on Bernardina, which DALL (1910)
had dedicated to Felix Bérnard, a pioneer worker on the devel-
opment of the bivalve hinge.

small specimens of the eastern Pacific venerid genera
Transennella, Nutricola, Pitar, or Psephidia. In addition to
the features given above, Halodakra has a posterior lateral
tooth in its left valve and a slot for it in the right, features
not present in these venerids.

The following is a key to the four species of the Ber-
nardinidae:

A. Anterior end longer than posterior; concentric sculp-
ture of heavy ribs; posterior lateral tooth absent; 3
cardinals present in each valve ........ Bernardina
(1) Prodissoconch set off by a prominent, raised ring;

concentric ribs wide; proportionately higher (1/h =
1:1); attains)3 mm in length 55 eee B. bakeri
(2) Prodissoconch set off by a low, raised ridge; con-
centric ribs narrow; lower (1/h = 1.2); minute, at-
tainsionly 2:4 3mm. = ee eee B. margarita

B. Posterior end longer than anterior; concentric sculpture
of fine threads; posterior lateral present; 3 cardinals in
left valve; 25in\ right 5. eee Halodakra
(1) Left valve without an anterior lateral tooth; oval

and elongate (1/h = 1.3); white, generally with a
radial row of brown chevrons; attains 4.5 mm in
length eee H.. (Halodakra) subtrigona
(2) Left valve with an anterior lateral tooth, right valve
with a slot for it; generally higher, trigonal (1/h =
1.2); entire shell white, salmon, or brown, without
a radial row of brown chevrons; attains 4.3 mm in
length> 7 Sa eiereee H. (Stohleria) salmonea

Bernardina Dall, 1910

Bernardina DALL, 1910:171-172; type species (original des-
ignation): B. baker: Dall, 1910.

Anterior end longer than posterior; sculpture of heavy
concentric ribs; three cardinal teeth present in each valve;
large anterior lateral present in left valve, well spaced
from cardinals; no posterior lateral present.

Bernardina baker: Dall, 1910
(Figures 1, 2)

Bernardina baker: Dall, 1910
DaLL, 1910:171-172
DALL, 1916a:24
DALL, 1921:30
OLDROYD, 1925:108-109; pl. 15, figs. 7, 8
EMERSON, in BURCH, 1944a:19; BURCH, 1944a:19
BuRCH 1944b:7, 1 fig.; BURCH, 1945:11
BERNARD, 1983:49

Type material and locality

USNM 220099, lectotype (herein), a right valve; length,
2.5 mm; height, 2.2 mm; thickness, 0.7 mm (pair
would have been 1.4 mm thick) (Figure 1). USNM
792413, paralectotypes, 7 pairs, 40 valves. The lec-
totype is the only specimen in the lot that comes close
to the originally stated length of 2.8 mm.

E. Coan, 1984

Page 229

Isla Coronado del Sur, Baja California Norte, Mexico
(32°24'N, 117°15’W); 5.5 m; F. Baker.

Description

Small (to 3.0 mm in length; LACM 63-41, Middle Isla
Coronado, Baja California Norte); triangular, length 1.1
times height; anterior end longer, rounded; posterior end
slightly angled; inflated, thickness 0.5 times height. Sur-
face with large, rounded concentric ribs that become
broader ventrally; prodissoconch set off by a raised ring.
Color white.

Right valve with a narrow anterior cardinal, a broad
central cardinal, and a narrower posterior cardinal. An-
terior end with a broad slot for lateral of left valve, distant
from cardinals; both sides of slot swollen into teeth. Left
valve with a narrow anterior cardinal, a broad central
cardinal, and a very narrow posterior cardinal, the liga-
ment just posterior to it. Anterior end with a large lateral,
well spaced from cardinals (Figure 2).

Geographic distribution and habitat

Pacific Grove, Monterey Co., California (36°37'42’N,
121°54’48"W) (LACM 72-88), to Isla Natividad, Baja
California Sur (27°52'N, 115°11'W) (LACM 72-116); in-
tertidal area to 24 m, with a mean depth of 10 m; among
rubble in rocky areas. Not uncommon; I have examined
47 lots. I have not located any specimens to confirm
BurRCH’s (1944a:19) record from Bahia Magdalena, Baja
California Sur, but the following species does occur there.
Example of a lot with a brood: LACM 63-41.

This species has been reported from the Pleistocene of
three of the Channel Islands of southern California: An-
acapa (VALENTINE & Lipps, 1963:1294, 1297) and San
Nicolas (VEDDER & Norris, 1963:46-47, 50), both Ven-
tura Co.; and Santa Barbara, Los Angeles Co. (Lipps et
al., 1968:297, 299).

Bernardina margarita (Carpenter, 1857)
(Figures 3, 4)

Circe margarita Carpenter, 1857
CARPENTER, 1857a:247, 306 [nomen nudum]
CARPENTER, 1857b:81, 82
DALL, 1902b:408 [indeterminate juveniles]
KEEN, in BuRCH, 1944b:17 [juvenile venerids]
Haas, 1945:4—-5 [indeterminate juveniles]
PALMER, 1951:20 [Circe]
KEEN, 1958:140 [juveniles, possibly venerids]; 622

[Lasaea]

BRANN, 1966:34, pl. 9, fig. 114 [Circe]
KEEN, 1968:394, 395, fig. 4 [Bernardina]
KEEN, 1971:118, 117, fig. 264
BERNARD, 1983:49

Type material and locality

BM(NH) 1857.6.4.412, lectotype (KEEN, 1968), pair;
length, 1.15 mm; height, 0.95 mm; thickness, 0.8 mm

(Figure 3). Other specimens now in lot, paralecto-
types, one minute pair, 1 left valve. USNM 715784,
paralectotypes, 3 valves.

Mazatlan, Sinaloa, Mexico (23°12'N, 106°25'W); F.
Reigen, 1848-1850.

Description

Minute, smaller than Bernardina baker: (to 2.4 mm in
length; LACM 72-121, Isla Guadalupe, Baja California
Norte); trigonal, but slightly more elongate than B. baker,
length 1.2 times height; anterior end longer, sharply
rounded; posterior end quadrate; inflated, thickness 0.5
times height. Surface with conspicuous concentric ribs,
finer than those in B. bakeri; prodissoconch set off by a
ridge less prominent than that in B. bakert. Color white,
tan, pink, or brown, sometimes with lighter blotches; more
colorful than B. baker.

Hinge very similar to that of B. bakeri? (Figure 4).

Distribution and habitat

Northwest side of Isla Guadalupe, Baja California Norte
(29°11'18”N, 118°15'12”W) (LACM 72-121), in the Gulf
of California as far north as Guaymas, Sonora (27°58'N,
111°911'W) (LACM 68-13), and southward to Bahia Ban-
deras, Jalisco (20°32'N, 105°19'W) (LACM 69-18 & 71-
83), all in Mexico; intertidal area to 21 m, with a mean
depth of 16 m; in rubble in rocky areas. Not common; I
have examined only 21 lots. Example of a lot with a
brood: LACM 72-121.

Discussion

This species was proposed in the genus Circe SCHUMA-
CHER, 1817 (pp. 50, 152), which is now placed in the
Veneridae. However, CARPENTER (1857b) realized that
his new species had an internal ligament, and he placed
Circe in the Astartidae.

Halodakra Olsson, 1961

Halodakra OLSSON, 1961:319, 472; type species (original
designation): ?Circe subtrigona Carpenter, 1857.

Posterior end longer than anterior; sculpture of fine
concentric threads; three cardinal teeth present in the left
valve, two in the right; posterior lateral present in the left
valve, a socket for it in the right. The name means “sea
tear.”

(Halodakra)

Without an anterior lateral tooth.

* KEEN (1971:118) described this species as having two car-
dinal teeth in the right valve, but like B. bakeri, it has three
cardinal teeth in each valve.

Page 230 ihe Veliger, Vole27peNow,

E. Coan, 1984

Halodakra (Halodakra) subtrigona (Carpenter, 1857)
(Figures 5-7)

Circe subtrigona Carpenter, 1857

CARPENTER, 1857a:247, 306 [nomen nudum]

CARPENTER, 1857b:82 [‘‘?Circe’’]

DALL, 1902b:408 [indeterminate juveniles]

KEEN, in BuRCH, 1944b:18 [possibly juvenile Petricola]

Haas, 1945:4-5 [Semele]

PALMER, 1951:20 [‘‘?Circe’’]

KEEN, 1958:140 [Circe, but indeterminate juveniles], 622
[Psephidia]

OLssON, 1961:319, 500 (pl. expl.), pl. 27, figs. 1-1c
[Halodakra|

BRANN, 1966:34, pl. 9, fig. 115 [‘‘?Circe”’]

KEEN, 1968:394, 396 [Halodakra]

KEEN, 1971:118, 117, fig. 265

BERNARD, 1983:49

Type material and locality

BM(NH) 1857.6.4.413, lectotype (herein), pair; length,
2.4 mm; height, 1.9 mm; thickness, 1.4 mm (Figure 5).
Other specimens in this lot, paralectotypes, 2 pairs,
one right valve. Field Museum of Natural History,
Chicago, 6698, paralectotype, right valve (Haas, 1945:
5). USNM 715785, paralectotypes, 1 pair, 10 valves.

Mazatln, Sinaloa, Mexico (23°12'N, 106°25'W); F. Rei-
gen, 1848-1850.

Description

Small (to 4.5 mm in length; LACM 71-83, Los Arcos,
Bahia Banderas, Jalisco, Mexico); ovate, length 1.3 times
height; anterior end sharply rounded; posterior end long-
er, broadly rounded; anterior end more expanded dorsally
than that in Halodakra salmonea; inflated, thickness 0.7
times height. Surface with fine concentric striae. White to
light brown, with dark brown flecks or chevrons in a ra-
dial row from beaks toward ventral margin posterior to
midline, often interspersed with white material; light
brown zig-zag lines also present on external surface in
many specimens. Dark brown color present on hinge an-
terior and posterior to umbones.

Right valve with a broad, elongate anterior cardinal
and a thin posterior cardinal, the resilifer posterior to it;
elongate slot present for anterior cardinal of left valve; slot
for posterior lateral of left valve still more elongate, its
ventral edge swollen to form a tooth. Left valve with an
elongate anterior cardinal, a short central cardinal, and a

Page 231

very thin posterior cardinal; ligament just posterior to the
latter; posterior end with a lateral tooth’ (Figure 7).

Geographic distribution and habitat

Tomales Bay, Marin Co. (38°15'N, 123°W) (AHF
1628-48), and Southeast Farallon Id., San Francisco Co.
(37°41'N, 123°W) (LACM 62-9), California, to and
throughout the Gulf of California, to El] Rubio and Punta
Mero, Tumbez Prov., Peru (3°54'S, 80°53’W) (LACM
72-85); Mancora, Tumbez Prov., Peru (4°6’S, 81°4'W)
(OLSSON, 1961); intertidal area to 24 m, with a mean
depth of 9 m; among rubble in rocky areas. Not uncom-

mon; I have examined 102 lots. Example of a lot with a
brood: LACM 63-11.

Discussion

This species has not previously been reported from Cal-
ifornia, specimens having been confused with H. salmonea.

Specimens from central California are elongate and oval.
They lack the characteristic radial row of dark brown
flecks, but similar specimens occur in southern California
and northern Baja California Norte along with more typ-
ical specimens. Material from central California is rare
in museums (only three lots), with no material in collec-
tions from between Carmel and Corona del Mar. It is
possible that when more material is available for study,
two taxa of Halodakra, s.s., will come into focus. I have
illustrated here (Figure 6) an elongate, oval specimen from
central California.

Stohleria Coan, subgen. nov.

Type species: Psephis salmonea Carpenter, 1864.

Differing from Halodakra, s.s., in the presence of an
anterior lateral tooth in the left valve and a slot for it in
the right valve.

The name of this subgenus honors Dr. Rudolf Stohler,
the founding editor of the journal The Veliger.

> OLSSON (1961) terms the broad anterior cardinal of the right
bivalve as “‘bifid.” His figure of the left valve seems to show a
cardinal tooth posterior to the ligament, but I see none there in
the material I have examined. He judges the combination of
what I consider the central and the posterior cardinals of the left
valve to be a single, bifid tooth.

et Explanation of Figures 1 to 4

Figures 1 and 2. Bernardina baker Dall.

Figure 1. Lectotype (herein). USNM 220099, length, 2.5 mm,
outside and inside views.

Figure 2. LACM 67-1, Puerto Santo Tomas, Baja California
Norte, 3-8 m, length, 2.8 mm. 2a, right valve. 2b, left valve.

Figures 3 and 4. Bernardina margarita (Carpenter).

Figure 3. Lectotype of Circe margarita Carpenter, BM(NH)
1857.6.4.412, length, 1.15 mm. 3a, outside views. 3b, inside views.

Figure 4. LACM 71-14, Punta Entrada, Bahia Magdalena, Baja
California Sur, 3-15 m, length, 2.0 mm. 4a, right valve. 4b, left
valve.

Page 232 The Veliger, Voll 2i/-NowZ

E. Coan, 1984

Page 233

Halodakra (Stohleria) salmonea (Carpenter, 1864)
(Figures 8-10)

Psephis salmonea Carpenter, 1864
CARPENTER, 1864:539, 611, 641 [1872:25, 97, 127]
CARPENTER, 1866:209
ARNOLD, 1903:18, 21, 37, 52, 75, 152
DALL, 1902b:408 [juvenile Tivela]
DALL, 1916a:34 [‘‘?Psephidia’’}
DALL, 1921:44 [““?Psephidia’’]
OLDROYD, 1925:162 [Psephidia; incorrectly cites a fig-
ure of Tellina salmonea|]
GRANT & GALE, 1931:338 [Psephidia]
BurCcH, 1944c:16; BURCH, 1945:16
PALMER, 1958:16, 20, 22, 37, 99, 336 (pl. expl.), pl.
11, figs. 6-12 [Psephidia]
BERNARD, 1983:49 [Halodakra]
Crassatella marginata Keep, 1887
KEEP, 1887:179 [As “CARPENTER” [KEEP, 1888, 1892,
1893:179]
PAETEL, 1890:139
KEeEp, 1904:50, 281
KELSEY, 1907:38 [Crassatella]
KEEP, 1911:61-62
ORCUTT, 1915:13 (1st sect.), 60 (2nd sect.)
Lamy, 1917:204
Keep & BAILEY, 1935:73 [Crassatellites]
BurcH, 1944b:9 [Crassatellites]; SMITH, in BURCH,
1944b:9 [unidentifiable]; KEEN, in BURCH, 1944b:
17 [Crassatella; probably synonym of Psephidia
brunnea]
PALMER, 1958:81
BERNARD, 1983:36 [synonym of Eucrassatella fluctuata
(Carpenter, 1864)]
Coan, 1984:164 [Halodakra; possibly synonym of H.
salmonea]
“Crassatellites margarita Carpenter,” auctt., non Circe mar-
garita Carpenter, 1857b
JORDAN, 1924:153
?“Tivela marginata Carpenter,” auctt.
DALL, 1902b:386
BERRY, 1907:20
Lamy, 1917:204
PALMER, 1958:96
Psephidia brunnea Dall, 1916
DALL, 1916a:34 [nomen nudum]
DALL, 1916b:413
DALL, 1921:44
OLDROYD, 1925:162
KEEN, in Burcu, 1944b:17
BurCcH, 1944c:16; BURCH, 1945:16
KEEN, 1971:118 [Halodakra]
BERNARD, 1983:49 [synonym of Halodakra salmonea]

Type material and localities

Psephis salmonea—USNM 15578, lectotype (herein),
pair; length, 3.0 mm; height, 2.7 mm; thickness, 2.0
mm (Figure 8). From Calif. State Geol. Surv. Coll.
no. 1068. San Diego, San Diego Co., California (about
32°33'N, 117°14'W; J. G. Cooper, probably Nov. or
Dec. 1861. Paralectotypes: Redpath Museum,
McGill University 115, 5 specimens; Santa Catalina
Id., Los Angeles Co., California (about 33°26'N,
118°29'W); 55 m; J. G. Cooper, June 20-26, 1863.

Crassatella marginata—The original type material has
not been located in the parts of the Keep collection
now housed at the University of California at Berke-
ley (D. Lindberg, verbal communication, Jan. 1983),
the California Academy of Sciences (B. Roth, verbal
communication, Jan. 1983), or the Institute of Ge-
ology & Paleontology of Tohoku Univ. in Sendai,
Japan (Ogasawara, in litt., 5 Sept. 1983). Neotype:
USNM 15578, the lectotype of Psephis salmonea,
which gives it the same type locality.

Psephidia brunnea—USNM 109469, lectotype (herein),
pair; length, 3.3 mm; height, 2.8 mm; thickness, 2.0
mm (Figure 9). Paralectotypes, USNM 792512, 1
broken and 4 entire pairs. Santa Catalina Island, Los
Angeles Co., California (about 33°26'N, 118°29'W);
29 m.

Description

Small (to 4.3 mm; LACM 67-61; Isla San Jeronimo,
Baja California Norte); ovate to almost triangular, length
1.2 times height; posterior end longer; anterior and pos-
terior ends rounded to sharply rounded; inflated, thickness
0.7 times height; beaks produced, more so than in Halo-
dakra (H.) subtrigona. Shell surface with fine concentric
striae. Color white, salmon, to brown, with darker brown
dorsally on either side of beaks, often with light brown
patches or wavy lines, which may also be visible on in-
ternal surface.

Right valve with a broad anterior cardinal and a nar-
rower posterior cardinal, the ligament well posterior to it.
Anterior end with an elongate slot for anterior cardinal
and anterior lateral of left valve, with distinct pits for each
of these teeth; ventral edge of this slot swollen to form a
lateral tooth; posterior end with an elongate slot for pos-
terior lateral of left valve, its ventral margin swollen into

Explanation of Figures 5 to 7

Figures 5 to 7. Halodakra (Halodakra) subtrigona (Carpenter).

Figure 5. Lectotype (herein) of Circe subtrigona Carpenter,
BM(NH) 1857.6.4.413, length 2.4 mm. 5a, outside views 5b,
inside views.

Figure 6. LACM 66-57, Carmel, California, intertidal area,
length, 2.5 mm. 6a, outside views. 6b, inside views.

Figure 7. LACM 71-151, northeastern end of Isla Cedros, Baja
California Norte, 6-12 m, length, 2.2 mm. 7a, right valve. 7b,
left valve.

Page 234 The Veliger, Vol. 27, No. 2

E. Coan, 1984

a lateral tooth. Left valve with a medium-sized anterior
cardinal, a medium-sized central cardinal, and a very thin
posterior cardinal bordering resilium. Anterior end with
a conspicuous lateral tooth, generally in line with anterior
cardinal. Posterior end with an elongate lateral (Figure
10).

Geographic distribution and habitat

Brookings, Curry Co., Oregon (42°2'42’N,
124°917'12”W) (LACM 63-35), to Punta San Hipolito,
Baja California Sur (26°58’N, 114°W) (USNM 127538;
CASIZ 039005); intertidal area to 60 m, with a mean
depth of 16 m; in gravel and rubble in rocky areas. Not
uncommon; I have studied 74 lots. Example of a lot with
a brood: LACM 63-50.

YOCUM & EDGE (1929:50) reported “Psephidia brunnea
Dall” from Coos Bay, Oregon, farther north than Brook-
ings. However, it is more likely that they had either Nu-
tricola tantilla (Gould, 1853) or Psephidia lord: (Baird,
1863), small venerids that occur there but are not present
on their faunal list. Their specimens have not been located
at the University of Oregon (P. Frank, in litt., 5 Jan.
1984).

VEDDER (1960:326) reported ‘“‘Psephidia cf. P. salmo-
nea’ from a Pliocene sandstone in Orange Co., California.
ARNOLD (1903: see synonymy) reported this species from
what is now regarded as the Lower Pleistocene of Santa
Barbara and of San Pedro, California. DELONG (1941:
facing p. 244) also recorded it from the latter.

Discussion

This species was first proposed in the venerid genus
Psephis Carpenter, 1864, which proved to be a homonym
(non Psephis GUENEE, 1854:257) and was renamed Pse-
phidia by DALL (1902a:243). It is unclear why Dall failed
to compare his new species, Psephidia brunnea, to P. sal-
monea, having placed them side by side in the same genus.

As discussed elsewhere (COAN, 1984), Crassatella mar-
ginata Keep, 1887, was most probably based on specimens
of Halodakra from southern California.* Keep credited this
species to Carpenter, but Carpenter never proposed it.
The name probably originated from the miscopying of a
label by Carpenter with some southern Californian spec-
imens of Halodakra salmonea that had been misidentified

4 This is sometimes misdated as 1888, but there was an 1887
printing of “West Coast Shells” that is less common in libraries
(see Literature Cited).

Page 235

by him as “Crassatella margarita (Carpenter, 1857)”
(CASIZ 036681). The latter species is a Panamic Ber-
nardina discussed herein.

BERNARD (1983:36) recently associated Keep’s taxon
with the rare, deep water Californian Eucrassatella fluc-
tuata (Carpenter, 1864). This is unlikely because Keep
had several specimens, and the Eucrassatella is still known
from only a few specimens, none resembling the “pin-
head”’-sized material that Keep said he had. Moreover,
Keep’s description demonstrates that he had good, prob-
ably live-collected material showing a color pattern.

I now recognize two species of Halodakra in southern
California, and it is difficult to be certain which of the
two Keep had. However, it is probable that he had H.
salmonea, the more common of the two forms there. The
neotype designation herein therefore serves to eliminate
future doubt and speculation.

It is uncertain what GARDNER (1917:113, pl. 4, fig. 12)
reported and illustrated from Laguna Beach, California,
as “Crassatella marginata.” It could have been either species
of Halodakra, and efforts to trace the specimens have been
unsuccessful (Oglesby, in litt., 25 Jan. 1984).

ACKNOWLEDGMENTS

I thank the personnel of the following institutions who
made material available for study: James H. McLean and
Gale Sphon of the Los Angeles County Museum of Nat-
ural History, Solene Morris of the British Museum (Nat-
ural History), Joseph Rosewater of the United States Na-
tional Museum of Natural History, Barry Roth and
Robert Van Syoc of the California Academy of Sciences,
Paul Scott of the Santa Barbara Museum of Natural His-
tory, Anthony D’Attillio of the San Diego Natural His-
tory Museum, David Lindberg of the University of Cal-
ifornia at Berkeley, and Mary Garback of the Academy
of Natural Sciences of Philadelphia.

I thank Bertram C. Draper for the photographs of type
specimens and Mary Ann Tenorio for the SEM photo-
graphs of the hinges. Robin Senour mounted the plates.

I appreciated comments on my manuscript by Barry
Roth, James McLean, Myra Keen, and Paul Scott, and
advice on aspects of this project by Peter Frank, Carole
M. Hertz, Kanshiro Ogasawara, and Larry C. Oglesby.

LITERATURE CITED

All works cited in the text, including sources of taxonomic
units are listed. Volume, bulletin, monograph, memoir,
and professional paper numbers are in bold face; series

Explanation of Figures 8 to 10

Figures 8 to 10. Halodakra (Stohleria) salmonea (Carpenter).

Figure 8. Lectotype (herein) of Psephis salmonea Carpenter, and
neotype (herein) of Crassatella marginata Keep, USNM 15578,
length, 3.0 mm. 8a, outside views. 8b, inside views.

Figure 9. Lectotype (herein) of Psephidia brunnea Dall, USNM
109469, length 3.3 mm. 9a, outside views. 9b, inside views.

Figure 10. LACM 71-151, northeastern end of Isla Cedros,
Baja California Norte, 6-12 m, length, 2.8 mm. 10a, right valve.
10b, left valve.

Page 236

The Veliger, Vol. 27 NowZ

numbers, in parentheses, precede volume numbers; issue
numbers, in parentheses, follow volume numbers; supple-
mentary information, such as second methods of listing
volumes, part numbers, and parenthetical statements, are
given in brackets. Plates and portraits are listed, but not
text figures, maps, charts, and tables. Exact publication
dates are given when possible.

ARNOLD, R. 1903. The paleontology and stratigraphy of the
marine Pliocene and Pleistocene of San Pedro, California.
Calif. Acad. Sci., Mem. 3:420 pp., 37 pls. (27 June 1903).

BAIRD, W. 1863. Descriptions of some new species of shells
collected at Vancouver Island and in British Columbia by
J. K. Lord, Esq., naturalist to the British North American
Boundary Commission, in the years 1858-1862. Zool. Soc.
London, Proc. for 1863(1):66-70 (May 1863).

BERNARD, F. R. 1982. Nutricola n. gen. for Transennella tan-
tilla (Gould) from the northeastern Pacific (Bivalvia: Ve-
neridae). Venus 41(2):146-149 (July 1982).

BERNARD, F. R. 1983. Catalogue of the living Bivalvia of the
eastern Pacific Ocean: Bering Strait to Cape Horn. Cana-
dian Spec. Publ. Fisheries & Aquatic Sci. 61:viii + 102 pp.
(about 15 April 1983).

Berry, S. S. 1907. Molluscan fauna of Monterey Bay, Cali-
fornia [first part]. Nautilus 21(2):17-22 (12 June 1907).

Boss, K. J. 1982. Mollusca. Vol. 1:945-1166 & Vol. 2:1092-
1096. In: S. P. Parker, ed., “Synopsis and classification of
living organisms.” McGraw-Hill: New York, N.Y.

BRANN, D.C. 1966. Illustrations to “Catalogue of the Collec-
tion of Mazatlan Shells” by Philip P. Carpenter. Ithaca,
New York (Paleo. Resh. Inst.) 111 pp., 60 pls. (1 April
1966).

BurcH, J.Q. 1944a. Extension of range of Bernardina bakeri
Dall. Conch. Club Southern Calif., Minutes 35:19 (May
1944).

BuRCH, J.Q. 1944b. [Families Astartidae and Crassatellidae].
In: “Distributional list of the West American marine mol-
lusks from San Diego, California, to the Polar Sea. Part I:
Pelecypoda.”’ Conch. Club Southern Calif., Minutes 39:5-
10, 17-18 (Sept. 1944).

BurcH, J. Q. 1944c. [Family Veneridae]. Jn: ibid. Conch.
Club Southern California, Minutes 42:3-18 (Dec. 1944).

Burcu, J. Q. 1945. Index. Jn: ibid. Conch. Club Southern
Calif., Minutes 45:20 pp. (March 1945).

CARPENTER, P. P. 1857a. Report on the present state of our
knowledge with regard to the Mollusca of the west coast of
North America. British Assn. Adv. Sci., Rept. 26 [for 1856]:
159-368 + 4 pp., pls. 6-9 (pre-22 April 1857).

CARPENTER, P. P. 1857b. Catalogue of the collection of Ma-
zatlan shells, in the British Museum: collected by Frederick
Reigen, .... London (British Mus.) i-iv + ix-xvi + 552 pp.
(1 Aug. 1857) [Warrington ed., published simultaneously]
[reprinted: Paleo. Resh. Inst., 1967].

CARPENTER, P. P. 1864. Supplementary report on the present
state of our knowledge with regard to the Mollusca of the
west coast of North America. Brit. Assn. Adv. Sci., Rept.
33 [for 1863]:517-686 (post-1 Aug. 1864) [reprinted: Car-
penter, 1872:1-172].

CARPENTER, P. P. 1865-1866. Descriptions of new marine
shells from the coast of California. Part III. Calif. Acad.
Sci., Proc. 3:207-208 (post-4 Sept. 1865); 209-224 (Feb.
1866).

CARPENTER, P. P. 1872. The mollusks of western North
America. Embracing the second report made to the British
Association on this subject, with other papers; reprinted by

permission, with a general index. Smithsonian Inst. Misc.
Colln. 10(252):xii + 325 + 13-121 pp. (Dec. 1872).

Coan, E. V. 1984. The Recent Crassatellinae of the eastern
Pacific, with some notes on Crassinella. Veliger 26(3):153-
169 (1 Jan. 1984).

Da.LL, W. H. 1902a. On the genus Gemma, Deshayes. J. Conch.
10(8):238-243 (1 Oct. 1902).

DaLL, W. H. 1902b. Synopsis of the family Veneridae and of
the North American Recent species. U.S. Natl. Mus., Proc.
26(1312):335-412, pls. 12-16 (29 Dec. 1902).

DaLL_, W. H. 1910. Description of a new genus and species
of bivalve from the Coronado Islands, Lower California.
Biol. Soc. Wash., Proc. 23:171-172 (29 Dec. 1910).

DaLL, W. H. 1916a. Checklist of the Recent bivalve mollusks
(Pelecypoda) of the northwest coast of America from the
Polar Sea to San Diego, California. Southwest Mus.: Los
Angeles. 44 pp., 1 port. (28 July 1916).

DaLL, W. H. 1916b. Diagnoses of new species of marine bi-
valve mollusks from the northwest coast of America in the
collection of the United States National Museum. U.S. Natl.
Mus., Proc. 52(2183):393-417 (27 Dec. 1916).

DatL_, W. H. 1921. Summary of the marine shellbearing mol-
lusks of the northwest coast of America, from San Diego,
California, to the Polar Sea, mostly contained in the collec-
tion of the United States National Museum, with illustra-
tions of hitherto unfigured species. U.S. Natl. Mus., Bull.
112:iii + 217 pp., 22 pls. (24 Feb. 1921).

DELonG, J. H. 1941. The paleontology and stratigraphy of
the Pleistocene at Signal Hill, Long Beach, California. San
Diego Soc. Natur. Hist., Trans. 9(25):229-252 (30 April
1941).

EMERSON, W. K. 1944. See BURCH (1944a).

GARDNER, L. L. 1917. A preliminary list of shells from La-
guna Beach and nearby. Pomona College, Dept. Zool., J.
Entomol. Zool. 9(3):107-118, pls. 1-5 (Sept. 1917).

GouLbD, A. A. 1853. Descriptions of shells from the Gulf of
California and the Pacific coasts of Mexico and California.
Boston J. Natur. Hist. 6(3):374-408, pls. 14-16 (Oct. 1853).

GRanT, U. S., IV & H. R. GALE. 1931. Catalogue of the
marine Pliocene and Pleistocene Mollusca of California and
adjacent regions .... San Diego Soc. Natur. Hist., Mem.
1:1036 pp., 32 pls. (3 Nov. 1931).

GuENEE, A. 1854. Histoire naturelle des Insectes. Species gén-
éral des Lépidoptéres 8:448 pp., 10 pls. Encycl. Roret: Paris.

Haas, F. 1945. Malacological notes—IV. Fieldiana (Zool.)
31(2):3-14 (19 Sept. 1945).

JORDAN, E. K. 1924. Quaternary and Recent molluscan fau-
nas of the west coast of Lower California. Southern Calif.
Acad. Sci., Bull. 23(5):145-156 (25 Oct. 1924).

KEEN, A. M. 1944. see BURCH (1944b).

KEEN, A. M. 1958. Sea shells of tropical west America; marine
mollusks from Lower California to Colombia. 1st ed. Stan-
ford Univ. Press: Stanford, Calif. xii + 624 pp., 10 pls. (5
Dec. 1958) [errata, pp. 625-626, bound in remaining books,
March 1959].

KEEN, A. M. 1963. Marine molluscan genera of western North
America; an illustrated key. Stanford Univ. Press: Stanford,
Calif. 126 pp. (14 Feb. 1963).

KEEN, A. M. 1968. West American mollusk types at the Brit-
ish Museum (Natural History) IV. Carpenter’s Mazatlan
collection. Veliger 10(4):389-439, pls. 55-59 (1 April 1968).

KEEN, A. M. 1969. Family Bernardinidae. Pp. N650. Jn: R.
C. Moore (ed.), “Treatise on Invertebrate Paleontology,”
L. R. Cox et al. (eds.), Part N (Bivalvia) 2:491-952. Geol.
Soc. Amer. & Univ. Kansas: Lawrence, Kansas.

E. Coan, 1984

KEEN, A. M. 1971. Sea shells of tropical west America; marine
mollusks from Baja California to Peru. 2nd ed. Stanford
Univ. Press: Stanford, Calif. xiv + 1064 pp., 22 pls. (1 Sept.
1971).

KEEP, J. 1887. West coast shells. A familiar description of the
marine, fresh water, and land mollusks of the United States,
found west of the Rocky Mountains. Bancroft Bros.: San
Francisco. 230 pp., frontis. (post-July 1887).

KEEP, J. 1888. [same title]. S. Carson: San Francisco. 230 pp.,

frontis.
KEEP, J. 1892. [same title]. S. Carson: San Francisco. 230 pp.,
frontis.
KEEP, J. 1893. [same title]. H. S. Crocker: San Francisco. 230
pp., frontis.

KEEP, J. 1904. West American shells. A description in familiar
terms of the principal marine, fresh water and land mollusks
of the United States found west of the Rocky Mountains,
including those of British Columbia and Alaska. Whitaker
& Ray: San Francisco. 360 pp., frontis. (post-11 July 1904).

KEEP, J. 1911. West coast shells (revised edition). A descrip-
tion of the principal marine mollusks living on the west coast
of the United States, and of the land shells of the adjacent
region. Whitaker & Ray-Wiggin: San Francisco. 346 pp.,
3 pls., frontis.

Keep, J. & J. L. Batty, Jr. 1935. West Coast shells: A de-
scription in familiar terms of the principal marine, fresh-
water, and land mollusks of the United States, British Co-
lumbia, and Alaska, found west of the Sierra. Stanford Univ.
Press: Stanford, Calif. & Oxford Univ. Press: London. xii
+ 350 pp. (post-1 Feb. 1935).

Kesey, F. W. 1907. Mollusks and brachiopods collected in
San Diego, California. San Diego Soc. Natur. Hist., Trans.
1(2):31-55.

Lamy, E. 1917. Révision des Crassatellidae vivants du Mu-
séum d’Histoire Naturelle de Paris. J. Conchyl. 62(4):197-
270, pl. 6 (17 Feb. 1917).

Lipps, J. H., J. W. VALENTINE & E. MITCHELL. 1968. Pleis-
tocene paleoecology and biostratigraphy, Santa Barbara Is-
land, California. J. Paleo. 42(2):291-307 (29 April 1968).

OLpRoyD, I. S. 1925. The marine shells of the west coast of
North America 1 [Pelecypoda]. Stanford Univ. Publ., Univ.

Page 237

Ser., Geol. Sci. 1(1):247 pp., 57 pls. (Sept. 1925) [not “1924”;
reprinted, Stanford Univ., April 1978].

O.sson, A. A. 1961. Mollusks of the tropical eastern Pacific
particularly from the southern half of the Panamic-Pacific
faunal province (Panama to Peru). Panamic-Pacific Pele-
cypoda. Paleo. Resh. Inst.: Ithaca, NY. 574 pp., 86 pls. (10
March 1961).

OrcuTT, C. R. 1915. Molluscan world 1. Orcutt: San Diego,
Calif. 62 + 208 pp. (post-1 Aug. 1915).

PAETEL, F. 1890-1891. Catalog der Conchylien-Sammlung
von .... 3 [Die Acephalen und die Brachiopoden]. Paetel:
Berlin. 23 + 256 + xxxii pp.

PaLMER, K. E. H. 1951. Catalog of the first duplicate series
of the Reigen collection of Mazatlan shells in the State Mu-
seum at Albany, New York. New York State Mus., Bull.
342:79 pp., 1 pl. (Jan. 1951).

PALMER, K. E. H. 1958. Type specimens of marine Mollusca
described by P. P. Carpenter from the West Coast (San
Diego to British Columbia). Geol. Soc. America, Mem. 76:
viii + 376 pp., 35 pls. (8 Dec. 1958).

PONDER, W. F. 1971. Some New Zealand and subantarctic
bivalves of the Cyamiacea and Leptonacea with descriptions
of new taxa. Dominion Mus., Rec. 7(13):119-141, 1 pl. (23
April 1971).

SCHUMACHER, C. F. 1817. Essai d’un nouveau systéme des
habitations des vers testacés. Schultz: Copenhagen. [iv] +
287 pp., 22 pls. (post-1 March 1817).

SMITH, A. G. 1944. See BURCH (1944b).

VALENTINE, J. W. & J. H. Lipps. 1963. Late Cenozoic rocky-
shore assemblages from Anacapa Island, California. J. Pa-
leo. 37(6):1292-1302 (14 Dec. 1963).

VEDDER, J.G. 1960. Previously unreported Pliocene Mollusca
from the southeastern Los Angeles Basin. U.S. Geol. Surv.
Prof., Paper 400-B:326-328.

VEDDER, J.G. & R. M. Norris. 1963. Geology of San Nicolas
Island, California. U.S. Geol. Surv., Prof. Paper 369:vi +
65 pp., frontis., 5 pls.

Yocum, H. B. & E. R. EpGe. 1929. The Pelecypoda of the
Coos Bay region, Oregon. Nautilus 43(2):49-51 (17 Oct.
1929).

The Veliger 27(2):238-241 (October 5, 1984)

THE VELIGiR
© CMS, Inc., 1984

A Technique for Determining Apparent Selective

Filtration in the Fresh-water Bivalve

Elliptio complanata (Lightfoot)

COLIN G. PATERSON

Department of Biology, Mount Allison University,
Sackville, New Brunswick, Canada EOA 3C0

Abstract. Elliptio complanata (Lightfoot) filtering natural lake water shows a marked selectivity for
smaller particles. Selection is for particle size rather than type as similar results were obtained when
the bivalves were held in suspensions of animal charcoal. Filtration rate varies with particle abundance
with the highest rates occurring at intermediate particle densities.

INTRODUCTION

AN EXTENSIVE literature exists on the filtration rates of
marine bivalves as modified by a variety of extrinsic fac-
tors. Many of these studies have determined filtration rate
from the rate of disappearance from the medium of or-
ganic and/or inorganic particles of a limited size range
and of fixed abundance. Such determined values have only
restricted applicability unless it is assumed that particle
size and abundance do not modify apparent filtration rate.
In contrast, numbers of authors have shown that mea-
sured filtration rate varies with particle size (VAHL, 1973;
BAYNE et al., 1977), abundance (RICE & SMITH, 1958;
ALI, 1970; TENORE & DUNSTAN, 1973; FOSTER-SMITH,
1975; WipbDows et al., 1979), and type (size?)(RICE &
SMITH, 1958).

Studies on fresh-water unionid bivalves are sparse in
comparison with those on marine species. ALLEN (1914),
using Lampsilis luteolus, and DE BRUIN & DaAvibs (1970),
using Anodonta cygnea, measured pumping rate by a direct
method. SALANKI & LUKACSOVICS (1967) determined the
rate of uptake of neutral red stain in Anodonta cygnea.
Neither of these techniques is suitable for determining the
effect of particle size, abundance, or type on filtration rate.
LEWANDOWSKI & STANCZYKOWSKA (1975) used an indi-
rect method to obtain limited results on filtration rates of
Anodonta piscinalis and Unio tumidus.

The present study was undertaken to determine wheth-
er a species of fresh-water unionid bivalve, Elliptio com-
planata (Lightfoot), would show responses to variations in
particle size, abundance, and type, as has been found in
many marine species.

MATERIALS anpD METHODS

During the summer months, specimens of Elliptio com-
planata were collected by dragging in Morice Lake, a
relatively old (ca. 1765) polymictic, mesotrophic reservoir
located approximately 3 km north of Sackville, New
Brunswick, Canada. The collecting site is described in
more detail by SEPHTON et al. (1980). At a shore labora-
tory, specimens were placed in a 55 x 115 cm polyeth-
ylene tank with an outlet drain located 30 cm above the
bottom. Natural lake water was continuously pumped from
an inlet located 20 cm above the lake bottom 15 m from
the shore and supplied to the holding tank at a rate of 75
L/h. Aeration was continuous. Experiments were con-
ducted in six plastic containers measuring 27.5 X 23.5 cm
and having a depth of 14 cm. Containers were equipped
with outlet valves 8.5 cm from the container bottom
through which water samples were obtained. Six liters of
freshly pumped lake water were added to each container.
Five specimens of E. complanata with a maximum length
of 6-7 cm were gently scrubbed and placed into each of
four containers. The remaining containers served as con-
trols.

At the initiation of the experiment, 50 mL water sam-
ples were removed through the outlet of each container
and diluted 1:1 with an electrolyte solution; then, 2 mL
samples were passed through a 200 wm aperture of a
model TAII Coulter Counter equipped with a Population
Mode. In all cases, triplicate particle counts were taken
and averaged. This procedure was then repeated after 2
h. When a particle passes through the aperture it is count-
ed as well as being assigned to one of 14 channels (channel

C. G. Paterson, 1984

Table 1

Particle size distribution as monitored by the Coulter
Counter using a 200 um aperture.

Minimum

Mean geometric Minimum volume diameter
Channel volume (um?) (um?) (um)
3 47.39 33.51 4.00
4 94.78 67.02 5.04
5 189.6 134.0 6.35
6 379.1 268.1 8.00
W 758.3 536.2 10.08
8 1516 1072 12.70
9 3033 2145 16.00
10 6066 4289 20.20
11 12.13 x 10° 8579 25.40
12 24.27 x 103 17.16 x 10° 32.00
13 48.54 x 10° 34.31 x 10° 40.30
14 97.18 x 10° 68.63 x 10° 50.80
5 194.4 x 10% 137.3 x 10° 64.00
16 388.7 x 10° 274.5 x 10% 80.60

3 through channel 16) based on particle size. The mean
geometric volume, minimum volume, and minimum di-
ameter of the particles measured by each channel when a
200 wm aperture is used are given in Table 1. Because
particle counts in channels 7 to 16 were too low to accu-
rately determine filtration rate these particle counts were
pooled. Background count due to the electrolyte solution
was determined and suitable corrections made. Details on
the application of the Coulter Counter to research of this
nature may be found in SHELDON & PARSONS (1977),
MayzauD & POULET (1978), POULET (1978), and Har-
BISON & MCALISTER (1979).

At the end of an experiment, the length (L) of each
bivalve in a container was determined to the nearest 0.5
mm using calipers, and the individual dry tissue weight
(W) was determined from the regression equation:

log,.W (g) = —2.403 + 2.770 log,,L (cm)

(GAMERON & et al., 1979). Individual weights in each
container were averaged and filtration rate determined as
mL/g/h for this average weight using the formula:

FR (mL /g/h)
I; log.P, — log.(P,7 + (P.° — P..)) x V (mL)
DSS) S\N)

where P = particles/mL, 0 = time 0, t=time 2 h, c=
control, T = test, V = volume (mL), W = average dry tis-
sue weight (g), and FR = filtration rate (mL/g/h).
Temperature was monitored in all experiments and
ranged from a low of 19.0°C to a high of 22.7°C. No
corrections have been attempted for these minor fluctua-
tions. The containers were not aerated during the exper-
iments as this would re-suspend pseudofaeces. This pro-

Page 239

duces a possible error due to natural particle settling which
is corrected for by determining the decline in the number
of particles in each channel in the control containers.

This experimental approach was repeated on 18 occa-
sions during the summer, and some variability in absolute
filtration rates was observed which could have been a
product of either fluctuations in particle abundance or in
the nature of the particles. During August when the lake
water remained at a relatively constant temperature of
about 20°C, natural lake water was filtered through 3.0-
pm Millipore filters and the filtrate used to make four
dilutions of lake water. Two experiments were conducted
each day. Each experiment consisted of two replicates of
each of two of the particle densities and an appropriate
control for each density. A total of eight replicates were
determined for natural lake water and for each of the four
dilutions. The sequence of replicates was staggered over
the 10 days of the experiment in order to compensate for
minor changes in particle concentration of the lake water
during this period of time.

In an attempt to determine whether the apparent higher
filtration rates observed for smaller particles was a prod-
uct of reduced particle size or a result of the nature of the
particles, further experiments were conducted in which
technical animal charcoal was used to make a dense sus-
pension in 3.0 wm filtered lake water. Amounts of sus-
pension were added to containers of 6 L of 3.0 um filtered
lake water to produce a total particle count approximating
13,000 particles/mL. Five bivalves between 6 and 7 cm
in length were added to each of four containers while the
other two remained as controls. This experiment was rep-
licated five times.

RESULTS

During the summer, filtration rate as determined from
total particle counts or counts from specific channels
showed little variation on any one day and often remained
relatively constant over several days of stable weather.
However, over the course of the summer, fluctuation in
filtration rate did occur which might relate to seasonal or
storm-induced changes in abundance and/or nature of the
particles. When all data are pooled and the filtration rate
in each channel changed to a percentage of the filtration
rate calculated from channel 3 (Figure 1), a significant
linear decline in relative filtration rate is found which can
be adequately described by the equation: RFR = 176.8 —
23.95N (n= 67, r= 0.89, P < 0.001) where RFR is the
relative filtration rate expressed as a percentage of that
determined for channel 3 and N is the channel number.
For the pooled 7-16 channels, channel 7 was used. The
fitted line passes through the mean value for all channels
except 3. That some curvilinearity exists between chan-
nels 3 and 4 is apparent from the intercept at channel 3,
where the calculated RFR is 104.95%, although all ob-
served filtration rates for this channel were set at 100%.
As shown in Table 1, the mean geometric volume doubles

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Figure 1

Elliptio complanata. Apparent filtration rate for each channel
number expressed as a percentage of that determined for channel
3. Vertical bars represent one standard error about the mean.

304

244

Filtration rate ml/g dry tissue/h (x 10)

T Ts =U T T T T T T T
I

13 I5 \7
Total initial particle abundance (x 103)

Figure 2

Elliptio complanata. Apparent filtration rates for total particle
counts (dashed line), channel 3 (@), channel 4 (¥), channel 5
(@), channel 6 (O) and pooled results from channels 7 through
16 (QO).

Elliptio complanata. Apparent filtration rates of technical animal
charcoal expressed as a percentage of that determined for chan-
nel 3. Vertical bars represent one standard error about the mean.

from one channel to the next. Thus, a negative exponen-
tial decline in relative filtration rate occurs which is well
described by the equation: RFR = 230 — 76.3 log, V,
where V is the mean geometric volume for the channel.
The number of particles in channel 7 is always substan-
tially higher than in 8 through 16 so a mean geometric
volume of 758.3 um? was used for this channel group.

To test the possible effect of particle abundance on the
variation observed over the summer, lake water collected
over a limited time period was used to determine filtration
rate in the unmodified water and in four dilutions (Figure
2). At the lowest seston concentration, all channels pro-
duced relatively similar filtration rate values. This might
be brought about by a reduced pumping rate, which al-
lows more time for successful filtration of the larger par-
ticles. An increase in average initial particle abundance to
11,000/mL caused a maximum filtration for most chan-
nels. Further increases in particle abundance resulted in
a decline in the apparent filtration rate as calculated from
particle uptake in all channels with the exception of chan-
nel 3. Filtration calculated for counts in this channel re-
mained relatively constant over the particle range of
11,000-15,000/mL and then declined. The decreasing fil-
tration rate with increasing channel number and, thus,
particle size (Figures 1, 2) could result either from some
active or passive “selection” operating on particle size as
such or from selection on the nature of the particles. Fig-
ure 3 shows the results obtained when apparent filtration
rate was determined using animal charcoal. A significant
decline in apparent filtration rate occurs as the particle
size increases from channel 3 through channel 6 and then
remains constant.

C. G. Paterson, 1984

DISCUSSION

The filtration activities of Elliptio complanata, at least as
measured under summer conditions, show many patterns
that are similar to those of marine filter-feeding bivalves.
As found for marine forms by RICE & SMITH (1958),
TENORE & DUNSTAN (1973), FOSTER-SMITH (1975), and
Wippows et al. (1979), filtration rate is lower at low
particle concentrations and then increases to a peak value.
After this peak is reached, there is then a decline as par-
ticles increase in abundance.

Like many marine bivalves (VAHL, 1973; BAYNE et al.,
1977), Elliptio complanata also appears to show pro-
nounced selectivity. One obvious difference is that in the
marine species selectivity appears to be for particles with
equivalent spherical diameters between about 6 and 10
pm. In Elliptio complanata the selection is most definitely
for the smaller particle sizes with the highest filtration
rates normally being found for channel 3, which measures
particles with diameters between 4.00 and 5.05 um. The
results of the studies using animal charcoal suggest that
the selection is a passive one based on particle size and
not particle nature. If selection is passive for a particular
particle size, then it is interesting to interpret further the
results found in this and other studies where filtration rate
initially increases as particle abundance increases and then
decreases. Results such as those presented in Figure 2
could be explained on the basis of either changes in the
efficiency of particle retention or changes in actual pump-
ing rate. Although both mechanisms may well be opera-
tional, it would appear that changes in pumping rate can
at least partially explain the results. As shown in Figure
2, the apparent filtration rates at the lowest particle den-
sity were very similar for channels 3, 4, 5, and 6. At the
highest particle densities, the filtration rates, as measured
from these channel counts, began to approach some degree
of similarity. It might well be that, at low particle density,
water is pumped at a lower rate which allows more time
for actual filtration and, consequently, particles of all sizes
are retained efficiently. With an increase in particle abun-
dance, pumping rate increases. At this increased rate,
smaller particles are retained more effectively than larger
particles. JORGENSEN (1983) has argued that, in marine
filter feeders, an increase in the velocity of water passing
over the gill mechanisms, which would result from an
increased pumping rate, increases the efficiency of reten-
tion of smaller particles relative to larger ones. Perhaps
when the particle density becomes great enough, there is
no advantage in using energy to maintain an elevated
pumping rate, as a much reduced pumping rate will still
produce adequate food supplies.

It is apparent from the results of this study that the
determination of an accurate measure of filtration rate is
extremely difficult. To determine filtration activities of a
species such as Elliptio complanata, it would be necessary
to measure filtration in the natural seston suspensions of
the habitat. The apparent filtration rate would have to be
determined for essentially all particle sizes that the bivalve

Page 241

can effectively remove from the water. This would then
allow determination of the total amount of material re-
moved from the water in a given period of time. This
study also would have to be expanded to cover the seasonal
changes in the abundance and size distribution of the lake
seston.

LITERATURE CITED

AI, R. M. 1970. The influence of suspension density and
temperature on the filtration rate of Hiatella arctica. Mar.
Biol. 6:291-302.

ALLEN, W.R. 1914. The food and feeding habits of freshwater
mussels. Biol. Bull. 27:127-146.

Bayne, B. L., J. Wippows & R. I. E. NEWELL. 1977. Phys-
iological measurements on estuarine bivalve molluscs in the
field. Pp. 57-68. Jn: B. F. Keegan, P. O. Ceidigh & P. J.
S. Bogden (eds.), Biology of benthic organisms. Pergamon
Press: Oxford.

CAMERON, C. J., I. F. CAMERON & C. G. PATERSON. 1979.
Contribution of organic shell matter to biomass estimates of
unionid bivalves. Can. J. Zool. 57:1666-1669.

DE Bruin, J. P. C. & C. Davips. 1970. Observations on the
rate of water pumping of the freshwater mussel Anodonta
cygnea zellensis (Gmelin). Neth. J. Zool. 20:380-391.

FOSTER-SMITH, R. L. 1975. The effect of concentration of
suspension and inert material on the assimilation of algae
by three bivalves. J. Mar. Biol. Ass. U.K. 55:411-418.

HarsIson, G. R. & V. L. MCALISTER. 1979. The filter-feed-
ing rates and particle retention efficiencies of three species
of Cyclosalpa (Tunicata, Thaliacea). Limnol. Oceanogr. 24:
875-892.

JORGENSEN, C. B. 1983. Fluid mechanical aspects of suspen-
sion feeding. Mar. Ecol. Prog. Ser. 11:89-103.

LEWANDOWSKI, K. & A. STANCZYKOWSKA. 1975. The occur-
rence and role of bivalves of the family Unionidae in Mi-
kolajskie lake. Ekol. Pol. 23:317-334.

Mayzaupb, P. & S. A. PoULET. 1978. The importance of the
time factor in the response of zooplankton to varying con-
centrations of naturally occurring particulate matter. Lim-
nol. Oceanogr. 23:1144-1154.

PouLeET, S. A. 1978. Comparison between five coexisting species
of marine copepods feeding on naturally occurring partic-
ulate matter. Limnol. Oceanogr. 23:1126-1143.

Rice, J.R. & R. J. SMirH. 1958. Filtering rates on the hard
clam (Venus mercenaria) determined with radioactive phy-
toplankton. U.S. Fish Wildl. Serv., Fish. Bull. 58:73-82.

SALANKI, J. & F. Lukacsovics. 1967. Filtration and O, con-
sumption related to the periodic activity of freshwater mus-
sel (Anodonta cygnea L.). Annal. Biol. Tihany. 34:85-98.

SEPHTON, T. W., C. G. PATERSON & C. H. FERNANDO. 1980.
Spatial interrelationships of bivalves and non-bivalve ben-
thos in a small reservoir in New Brunswick, Canada. Can.
J. Zool. 58:852-859.

SHELDON, R. W. & T. R. Parsons. 1977. A practical manual
on the use of the Coulter Counter in marine research. Coul-
ter Electronics Sales Company, Canada. 66 pp.

TENoRE, K. R. & W. M. Dunstan. 1973. Comparison of
feeding and bio-deposition of three bivalves at different food
levels. Mar. Biol. 21:190-195.

VAHL, O. 1973. Efficiency of particle retention in Chlamys
islandica (O. F. Muller). Astarte 6:21-25.

Wippows, J., P. FIETH & C. M. WorRALL. 1979. Relation-
ships between seston, available food and feeding activity in
the common mussel Mytilus edulis. Mar. Biol. 50:195-207.

The Veliger 27(2):242-243 (October 5, 1984)

THE V EGG
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Second International Cephalopod Symposium

The Second International Cephalopod Symposium will be
held in Ttibingen, Federal Republic of Germany from
16-23 July 1985. It is intended to bring together zoolo-
gists and paleontologists working on cephalopods, and the
following themes have been proposed: major evolutionary
Strategies, strategies in early development, migration and
global distribution, dietary habits and locomotion, post-

mortem processes, and buoyancy, vertical migration and
tiering in the water column. Several field trips are sched-
uled to occur before and after the sessions.

For further details, write to Prof. Jiirgen Kullmann,
Geol.-Palaont. Institut, Sigwartstr, 10, D-7400 Titibin-
gen, Federal Republic of Germany.

The Veliger 27(2):244 (October 5, 1984)

THE VELIGER
© CMS, Inc., 1984

BOOKS, PERIODICALS & PAMPHLETS

Illustration of the Types Named by S. Stillman Berry
in his “Leaflets in Malacology”

by CAROLE M. HERTZ. 10 January 1984. The Festivus,
volume 15, supplement. 42 pp., 92 figs. $5.00 plus $0.88
postage and California sales tax where applicable. (copies
available from the San Diego Shell Club, Inc., % 3883
Mt. Blackburn Ave., San Diego, California 92111).

How often, since Dr. Stillman Berry began his series
of ‘‘Leaflets,” have collectors and other students of west
American malacology complained because there were no
figures of the newly-described shells. At long last that lack
is remedied in a thoroughgoing way. Publication of the
figures simply had to wait until there came on the scene
the right combination of talents: photographers like Leroy
Poorman with the skill and the patience to search out and
make color slides of the holotypes, David Mulliner, who
could turn these into creditable black-and-white prints,
and an author, Carole Hertz, with the willingness not
only to get the illustrations together but also to compile,
with the complete list of species, the supplementary data
that are important to the systematist—(1) where are these
specimens now; (2) what synonyms have been suggested;
and (3) what are the titles among the “Leaflets” that carry
descriptions by Stillman Berry of new species. Carole Hertz
is highly to be commended for having carried through this
project in so efficient a way. She has provided also an
alphabetical index to the species names, a list of the new
genera described by S. S. Berry in the “Leaflets,” a three-
page bibliography, and a tabular summary of the eight
species of Octopus that were not practicable to be illus-
trated here.

This paper should win a niche for itself as one of the
significant modern contributions to west coast malacology.

Myra Keen

Distribution of Shallow-water Marine
Mollusca, Yucatan Peninsula, Mexico

by HaROLD E. VoKEs & EMILY H. VOKEs. 1983. Middle
American Research Inst., Tulane Univ., New Orleans,
Louisiana. Mesoamerican Ecol. Inst., Monogr. 1:viii +
183 pp., 50 pls. $21.50.

This is an illustrated checklist based on collections by
the late archaeologist E. Wyllys Andrews, IV, to whom

the work is dedicated, and by the Vokes themselves. Some
769 intertidal and shallow-water species are reported from
the seven regions the authors identify on the peninsula.
Special lists highlight the taxa most characteristic of the
entire peninsula and of the north and west coasts, which
are on the Gulf of Mexico, and the east coast, which is
on the Caribbean.

Each species is well illustrated, mostly by photographs,
though not necessarily of specimens from Yucatan. In the
systematic list, the original reference and combination are
given, as well as a second reference, generally to Abbott’s
American Seashells (1974). Very few taxonomic and no-
menclatural remarks are in this list. A second table gives
the occurrence of the species in the seven regions, with an
indication of their relative abundance in the collections.
No habitat information is presented.

This checklist should prove useful both to visitors to
this area as well as to specialists wanting some informa-
tion about this previously poorly studied peninsula.

E. V. Coan

Proceedings of the Second Franco-British
Symposium on Molluscs

ALAN BEBBINGTON (editor). Proceedings of the Second
Franco-British Symposium on Molluscs. Journal of Mol-
luscan Studies, Supplement 12A:227 pp. Priced at 30
pounds (20 pounds to members of the Malacological So-
ciety of London). Copies may be purchased from The
Editor, Journal of Molluscan Studies, Dept. of Zoology,
Univ. of Reading, Whiteknights Park, Reading, Berk-
shire, U.K.

The majority of papers delivered at the Second Franco-
British Symposium on Molluscs, held in London from 6
to 9 September 1982, are presented in this special sup-
plement to the Journal of Molluscan Studies. The volume
contains 36 papers (29 in English, 7 in French) and 12
posters (10 in English, 2 in French). Mollusks from many
parts of the world are represented, including a few from
the eastern Pacific, and the papers cover a wide range of
topics, including evolution, biogeography, ecology, behav-
ior, physiology, and anatomy. In short, something is here
for everyone interested in mollusks.

D. W. Phillips

Information for Contributors

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a) Periodicals
Cate, J. M. 1962. On the identifications of five Pacific Mitra. Veliger 4:132-134.

b) Books
Yonge, C. M. & T. E. Thompson. 1976. Living marine molluscs. Collins: London.
288 pp.

c) Composite works

medemek. Mi. 1980: Asteroidea: the sea.stars. Pp. 117-135. In: R. H. Morris, D. P.
Abbott & E. C. Haderlie (eds.), Intertidal invertebrates of California. Stanford Univ.
Press: Stanford, Calif.

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CONTENTS — Continued

Comparison of Acteocina canaliculata (Say, 1826), A. cande: (d’Orbigny, 1841),
and A. atrata spec. nov. (Gastropoda: Cephalaspidea).
PAUL S: MIKKELSEN AND» PAULAy Mi MIKKELSEN: se) epee ee 164

Pseudo-operculate pulmonate land snails from New Caledonia.
ALAN SOLEM, SIMON TILLIER, AND PETER MORDAN ..!........5.-. 550m 193

Lysinoe (Gastropoda: Pulmonata) and other land snails from Eocene-Oligocene
of Trans-Pecos Texas, and their paleoclimatic significance.
BARRY ‘ROTH! 5 60s (455 fa PN RUN eee A a 200

The genera Moelleria Jeffreys, 1865, and Spiromoelleria gen. nov. in the North
Pacific, with description of a new species of Spiromoelleria (Gastropoda:
‘Turbinidae).

RAE BAXTER AND JAMES TL; MCEEAN 129 29922-- 927 0 219

The Bernardinidae of the eastern Pacific (Mollusca: Bivalvia).
EUGENE (COAN( 8 eile 3 Oeil le) cpa ry ae Aes eae et a ne a Sse Oe

A technique for determining apparent selective filtration in the fresh-water bi-
valve Elliptio complanata (Lightfoot).
GOLIN. G. PATERSON i's 3. 2 8223 bah ng ge a Oe 238

NOTES, INFORMATION & NEWS

“WILLIAM H. DALY :
f SECTIONAL LIBRARY = ISSN 0042-3211

THE, _ DIMISION.OF MOLLUSKS

Vv ELIGER

A Quarterly published by

CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC.
Berkeley, California

R. Stohler, Founding Editor

Volume 27 January 2, 1985 Number 3

CONTENTS

Form, function, and origin of temporary dwarf males in Pseudopythina rugifera
(Carpenter, 1864) (Bivalvia: Galeommatacea).
DARIAN @) AHOMGHIEL cs ate Ue 2 ce Swe ade Ey heey ee GLEN 245

Life-habits and infaunal posture of Cumingzia tellinoides (Tellinacea, Semelidae):
an example of evolutionary parallelism.
VW) SRUSSELE-EIUNTDER AND JAY S. WASHIRO 752) 0.4 ee ne de ee 253

Patterns of sex change of the protandric patellacean limpet Lottia gigantea (Mol-
lusca: Gastropoda).
DAVID) RoACINDBERG AND WILLIAM G.- WRIGHT, 2.) .52 0 0.430.0.-2022- 261

Sediment correlates to density of Crepidula fornicata Linnaeus in the Pataguanset
River, Connecticut.
STEPHEN H. LOOMIS AND WENDY VANNIEUWENHUYZE ................ 266

Histopathological and histochemical effects of larval trematodes in Goniobasis
virginica (Gastropoda: Pleuroceridae).
ANERE ELUPENMAN AND: BERNARD! PRIED)) (2.2 2.228 220.)202 bai ase: 212

Architectonica (Architectonica) karsteni (Rutsch, 1934): a Neogene and Recent
offshore contemporary of A. (Architectonica) nobilis Roding, 1798 (Gas-
tropoda: Mesogastropoda).

MIDETONUAS BA pe ODEN ARUES Svat Ne era ening ere! eb Ne AR WPM aed tes 8 282

The Stenoplax limaciformis (Sowerby, 1832) species complex in the New World
(Mollusca: Polyplacophora: Ischnochitonidae).
IN@OBERGIN CAMS WRUOC Ker aierrn sch amionrn enya! MEU her bik sar ale ae TN 291

CONTENTS — Continued

The Veliger (ISSN 0042-3211) is published quarterly on the first day of July, October,
January and April for $18.75 for affiliate members (plus mailing charges) and $37.50
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THE VELIGER

Scope of the journal
The Veliger is open to original papers pertaining to any problem concerned with mol-
lusks.

This is meant to make facilities available for publication of original articles from a
wide field of endeavor. Papers dealing with anatomical, cytological, distributional, eco-
logical, histological, morphological, physiological, taxonomic, etc., aspects of marine,
freshwater, or terrestrial mollusks from any region will be considered. Short articles
containing descriptions of new species or lesser taxa will be given preferential treatment
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type specimen must be included in the manuscript. Type localities must be defined as
accurately as possible, with geographical longitudes and latitudes added.

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of meetings, as well as news items that are deemed of interest to our subscribers in
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Editor-in-Chief
David W. Phillips, 2410 Oakenshield Road, Davis, CA 95616, USA

Editorial Board

Donald P. Abbott, Emeritus, Hopkins Marine Station of Stanford University
Hans Bertsch, Universidad Autonoma de Baja California

James T. Carlton, Williams College— Mystic Seaport

Eugene V. Coan, Research Associate, California Academy of Sciences, San Francisco
J. Wyatt Durham, University of California, Berkeley

Cadet Hand, University of California, Berkeley

Carole S. Hickman, University of California, Berkeley

A. Myra Keen, Emerita, Stanford University

David R. Lindberg, University of California, Berkeley

James H. McLean, Los Angeles County Museum of Natural History

Frank A. Pitelka, University of California, Berkeley

Peter U. Rodda, California Academy of Sciences, San Francisco

Clyde F. E. Roper, National Museum of Natural History, Washington
Judith Terry Smith, Stanford University

Ralph I. Smith, University of California, Berkeley

Wayne P. Sousa, University of California, Berkeley

T. E. Thompson, University of Bristol, England

Alex Tompa, University of Michigan, Ann Arbor

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The Veliger 27(3):245-252 ( January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

Form, Function, and Origin of Temporary Dwarf
Males in Pseudopythina rugifera (Carpenter, 1864)
(Bivalvia: Galeommatacea)
by

DIARMAID O FOIGHIL

Department of Biology, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada

Abstract. Female Pseudopythina rugifera (Carpenter, 1864) typically house a dwarf male within
their mantle cavity. Dwarf males show considerable morphological differences from females. The dwarf
male shell (<1.25 mm in length) is poorly developed, and a thin extension of the mid-mantle fold,
bearing sensory papillae, covers the valves. The foot has a sucker-like ventral surface, is hypertrophied,
and dorsoventrally compressed. Only one demibranch is present in the gills, and the visceral mass
contains a fully functional digestive system, as well as a relatively large testis. Larger male individuals
(2-5 mm in length) do not demonstrate sexual dimorphism and occur external to females. Some
individuals are hermaphroditic and all specimens >6 mm in length are female. Available data suggest
that P. rugifera is a protandrous hermaphrodite, with the dwarf male stage located inside the female
mantle cavity; further development, incorporating morphological changes and eventual sex reversal,
occurs external to the female host. Dwarf males may provide an efficient method of sperm transfer
where space restrictions in habitats normally prevent the co-occurrence of equal-sized adult conspecifics
of an outcrossing species. In the Galeommatacea, species with protandrous consecutive hermaphrodites
or with complemental males may be the immediate evolutionary precursors of the dwarf male condition.

INTRODUCTION

THE TERM “dwarf male” describes cases where miniature
males occur in or on a female (TURNER & YAKOVLEV,
1983). With the exception of the teredinid Zachsia zen-
kewitschi Bulatoff & Rjabtschikoff, 1933, dwarf males in
the Bivalvia are restricted to a few galeommatacean species
(TURNER & YAKOVLEV, 1983). JENNER & McCRARY
(1968) briefly describe the dwarf males of three species:
Montacuta percompressa Dall, 1899, Orobitella floridana
(Dall, 1899), and an undescribed species of Entovalva.
Pseudopythina subsinuata (Lischke, 1871) is a protandrous
hermaphrodite, the male stage being closely associated with
females and, when very small, males are occasionally found
within the mantle cavity of females (MorTON, 1972). Adult
female Ephippodonta (Ephippodontina) oedipus Morton,
1976, typically possess two dwarf males in a pair of pallial
pouches (Morton, 1976). Chlamydoconcha orcutti Dall,
1884, and Montacuta (Tellimya) phascolionis Dautzenberg

& Fischer, 1925, have also been reported to have dwarf
males (MoRTON, 1981; DEROUX, 1960); however, because
they occur in association with hermaphrodites rather than
females, they may be more accurately classified as com-
plemental males (see Discussion).

Pseudopythina rugifera, also placed in the genus Nea-
eromya (ABBOTT, 1974), is a relatively rare bivalve found
in the northeastern Pacific from Alaska to Lower Cali-
fornia (ABBOTT, 1974). ROSEWATER (1984) should be con-
sulted for the most recent evaluation of the Pseudopythina-
Neaeromya-Orobitella species complex. Typically, P. rug-
ifera occurs aS an ectocommensal, attached by byssus to
one of three host species, the mudshrimp Upogebia pu-
gettensis (Dana, 1852) or to two polychaete species,
Aphrodita japonica Marenzeller, 1879 and Aphrodita neg-
ligens Moore, 1905 (PETTIBONE, 1953; MACGINITIE &
MAcGINITIE, 1968). The female morphology has been
described in detail by NARCHI (1969), who found no males.

The morphology of dwarf male Pseudopythina rugifera

Page 246

is described here, and the possible factors leading to the
development of dwarf males in the Galeommatacea are
discussed.

MATERIALS anpD METHODS

A total of 24 specimens of Pseudopythina rugifera (not
including dwarf males) was obtained between October
1983 and June 1984. All but one individual were attached
to specimens of Aphrodita japonica or A. negligens, which
were dredged off San Juan Island, Washington State,
U.S.A. The polychaete hosts were then kept in an aquar-
ium at the Friday Harbor Laboratories for up to six
months (R. Strathmann, personal communication). One
specimen of P. rugifera was retrieved attached to the mud-
shrimp Upogebia pugettensis in Bamfield Inlet, on the west
coast of Vancouver Island, B.C., Canada, in April 1984
(D. Denning, personal communication). The specimens
of P. rugifera were examined using a dissecting microscope
and sexed by way of gonad squashes. Dwarf males present
were removed from the female hosts and measured with
an ocular micrometer. For optical histology, specimens
were relaxed in 6.7% MgCl, fixed in 5% glutaraldehyde
(biological grade), dehydrated in an ethanol series, embed-
ded in JB4 resin, sectioned at 2 wm, and stained in Gill’s
haematoxylin and eosin. For scanning electron microsco-
py, specimens were fixed in a 3:1 mixture of 4% glutar-
aldehyde and 1% osmium tetroxide in 3% NaCl (SMITH,
1983), dehydrated in acetone, critical point dried, gold
coated, and viewed with a JEOL JSM-35 scanning elec-
tron microscope. To investigate sperm ultrastructure,
specimens were fixed in 5% glutaraldehyde in 0.1 M cac-
odylate buffer with 0.25 M sucrose, post-fixed with os-
mium tetroxide in the same buffer, dehydrated in ethanol,
embedded in epon, and sectioned on a Reichert ultrami-
crotome. Silver-gray sections were stained with uranyl
acetate and lead citrate and viewed with a Phillips EM
300 transmission electron microscope.

RESULTS

Sixteen of the 24 individuals obtained were female, 4 were
male, 3 were hermaphroditic and one specimen did not
exhibit any gonad development. When dissected, 11 of the
16 females (including the specimen retrieved from Upo-
gebia pugettensis) contained one, and one female contained
two, dwarf males within their mantle cavity. Data on the
size frequency and sex of the specimens are presented in
Figure 1. All individuals <1.25 mm in valve length were
dwarf males occurring within the mantle cavity of female
hosts. All individuals >6 mm in length were females, and
specimens intermediate in size were male, hermaphrodit-
ic, or displayed no gonadal development.

Dwarf Male Morphology

The valves are poorly developed and gape widely; the
valve margins make contact only at the hinge line (Figure

The Veliger, Vole Zip Noms

NUMBER »

@ 2 |@

12 14 16

IZ)
EL aa

VALVE LENGTH [mm] &

Figure 1

Length frequency and sex of Pseudopythina rugifera sampled.
@, dwarf males; 6, males external to females; ¢, hermaphrodites;
@, females containing dwarf males; 9, females not containing
dwarf males; —, no gonad development.

2). The shell is whitish in color and semi-transparent. A
prominent prodissoconch was present in all specimens
(Figure 3) and ranged in length from 280 to 350 um. The
dissoconch bears concentric rings and faint radial lines.

An anterior pedal (inhalant) opening is separated from
a slitlike posterior exhalant opening by the extensive fu-
sion of the inner mantle fold (Figure 2). A shorter tract
of fusion occurs dorsally, anterior to the hinge. The mid-
mantle fold extends as a thin flap (1 or 2 cells thick) to
cover the external surface of the shell (Figures 2, 3, 6).
Papillae bearing apical tufts of cilia are present in this
extension (Figure 2). These cilia exhibit bulbous tips when
viewed by scanning electron microscope (Figure 4) and
resemble paddle cilia (TAMARIN et al., 1974), which have
been recorded from a wide variety of taxa and are thought
to have a sensory function (MATERA & Davis, 1982). In
the smaller specimens, the mid-mantle fold does not fully
cover the shell (Figure 3).

One of the most striking aspects of the dwarf male
morphology is the foot. It is hypertrophied, dorsoventrally
compressed, and cannot be withdrawn inside the shell. A
pleated posterior heel region is distinct from the non-
pleated anterior of the foot, and the ventral surface con-
tains a prominent ventral groove (Figure 5). The animals
are mobile; however, some individuals were attached by
byssus to the mantle of the female. The other dwarf males
were moving around the mantle cavity of their female
hosts.

The gills contain one demibranch, each composed of a
descending lamella only. No food groove is present, and
the lamellae fuse together medially behind the foot (Fig-

D. O Foighil, 1985

Explanation of Figures 2 to 5

Figure 2. Scanning electron micrograph of Pseudopythina rugifera relaxed in 6.7% MegCl,. e, exhalant siphon; f,
foot; i, inner mantle fold; m, mid-mantle fold; sp, sensory papillae.

Figure 3. Scanning electron micrograph of unrelaxed Pseudopythina rugifera dwarf male. p, prodissoconch-disso-

conch interface; u, umbone.

Figure 4. Scanning electron micrograph of Pseudopythina rugifera dwarf male sensory papilla. pc, paddle cilia.

Figure 5. Scanning electron micrograph of Pseudopythina rugifera dwarf male foot.

ure 6). The lamellae also fuse for much of their length
with the mantle.

A fully functional alimentary canal, containing esopha-
gus, stomach, style sac, digestive gland, and intestine is
present.

Each of the dwarf males examined possessed a testis,
although it differed in the degree of development. The
smallest individual (325 um in length) contained two small,
dorsal follicles with early gametogenic stages (spermato-
gonia and spermatocytes). In larger animals the entire
posterior region of the visceral mass was composed of a
bilobed testis, consisting predominantly of mature sperm

(Figure 6). This suggests that spermatogenesis is initiated
at an early stage, and that it is a continuous process. Two
dwarf males occurring inside newly spawned females ap-
peared spawned-out, with the testis containing some re-
sidual sperm.

Pseudopythina rugifera sperm consist of a conical head
5.3 ym in length and a flagellum (Figure 7). The acro-
some is apical, does not have an axial rod, and contains a
U-shaped, membrane-bound vesicle surrounding a lumen
of flocculent material (Figure 8). Four mitochondria in
the middle piece surround a pair of centrioles. Sperm mor-
phology in this species is typical of the primitive level of

Page 248

Figure 6

Light micrograph of a cross section through a dwarf male Pseu-
dopythina rugifera. g, gills; m, mid-mantle fold; pr, periostracum;
t, testis.

organization generally found in free-spawning marine in-
vertebrates (FRANZEN, 1970).

With the exception of the testis, the morphology of the
unenclosed males and hermaphrodites is as described by
NARCHI (1969) for female Pseudopythina rugifera.

DISCUSSION

The Galeommatacea display various degrees of shell re-
duction and mid-mantle fold hypertrophy, associated with
the development of a commensal habit (MorTON, 1976).
Pseudopythina rugifera shows a strong dimorphism in this
regard. Females and unenclosed males have a well-devel-

20 #m

The Veliger, Vol. 27, No. 3

oped shell and an unspecialized mantle (NARCHI, 1969;
personal observation), while the dwarf male shell is re-
duced and the mid-mantle fold enlarged. This may reflect
the relatively protected environment of the endocommen-
sal dwarf male within the female mantle cavity.

Additional morphological differences occur in the gills
and foot. In female and unenclosed male Pseudopythina
rugifera, the outer demibranch is present but is reduced in
size relative to the inner demibranch (NARCHI, 1969). The
lack of an outer demibranch in dwarf males may be a
consequence of their small size, because juvenile eulamel-
libranch bivalves possess only one demibranch during their
early development (STASEK, 1962). Foot morphology var-
ies markedly between dwarf males and females or unen-
closed males. The dorsoventrally compressed, suckerlike
form of the dwarf male foot contrasts with the laterally
compressed, slender foot of females and unenclosed males
(NARCHI, 1969; personal observation). Females and unen-
closed males attach to the ventral surface of Aphrodita by
means of a large byssus (NARCHI, 1969; personal obser-
vation). Dwarf males also attach by byssus production,
but, when moving around the female mantle cavity, they
may rely for adhesion on the large area of surface-to-
surface contact provided by the flattened foot.

The ciliated papillae present on the mid-mantle fold
extension resemble the mechanoreceptors of the septi-
branch Cardiomya planetica (Dall, 1908) as described by
REID & CrosBy (1980).

More than one dwarf male may locate in a single fe-
male Pseudopythina rugifera, as was reported by JENNER
& McCrary (1968) for Montacuta percompressa and by
MorTONn (1976) for Ephippodonta oedipus. In these cases,
the male spawning the largest amount of sperm coinciding
with egg release should fertilize the greatest number of
eggs. This would select for rapid sexual maturity in these
dwarf males, as appears to occur in P. rugifera.

Explanation of Figures 7 and 8

Figure 7. Phase contrast light micrograph of Pseudopythina rugifera sperm.

Figure 8. Transmission electron micrograph of Pseudopythina rugifera sperm.

D. O Foighil, 1985

NARCHI (1969) reported that in Pseudopythina rugifera
the embryos develop within the gills, but he did not dis-
cover at what stage they are released. Commensal galeom-
mataceans, with the exception of Montacuta phascolionis,
undergo a planktotrophic developmental stage (OCKEL-
MANN & Muus, 1978). Montacuta phascolionis has direct
development with a maximum fecundity of circa 73 em-
bryos (GAGE, 1979). Based on the relatively high fecun-
dity (thousands of embryos) of P. rugifera (personal ob-
servation), direct development is unlikely.

In the Galeommatacea, dwarf male morphology varies
from the extreme degeneration of Montacuta percompressa
(JENNER & McCrary, 1968), to Ephippodonta oedipus,
where the dwarf male is simply smaller than the female
(Morton, 1976). Secondary sexual characteristics are
moderately well developed in the other species with dwarf
males. The dwarf males of Orobitella floridana and an
undescribed Entovalva species are similar to Pseudopy-
thina rugifera in that they are shelled and possess an en-
larged foot (JENNER & McCrary, 1968).

Pseudopythina subsinuata is a protandric, consecutive
hermaphrodite. The males frequently attach to the byssus
of the larger females, and when very small occasionally
occur within the mantle cavity of females (MorTON, 1972).
Morton interpreted the P. swbsinuata life cycle as an initial
dwarf male phase followed by a female phase. The situ-
ation in Pseudopythina rugifera appears similar, with a
smaller male stage being linked to a larger female stage
by a period of simultaneous hermaphroditism (Figure 1).
The initial (dwarf) male phase locates inside the female
mantle cavity, and sex reversal occurs external to the fe-
male host. However, the role of the dwarf male stage may
differ in these two species. MORTON (1972) implies that
male Pseudopythina rugifera do not normally occur within
the female mantle cavity. Furthermore, sperm transfer
(presumably from unenclosed males) in P. subsinuata in-
volves a storage of sperm morulae or ripe sperm in the
suprabranchial chamber of females (MORTON, 1972).
Sexually mature male P. rugifera typically reside within
females, and the presence of spawned-out males occurring
inside newly spawned females suggests that the dwarf male
stage is largely responsible for sperm transfer in this
species. It is not known whether sperm storage in the
female suprabranchial chamber occurs in female P. rugi-
fera. MORTON (1976) suggests that dwarf males in P. sub-
stnuata evolved as a result of extreme protandry. Dwarf
males in P. rugifera may have evolved similarly.

Available information suggests that all galeommatacean
species may brood developing embryos in the suprabran-
chial cavity and/or the mantle cavity. The eggs are re-
leased into and fertilized in the suprabranchial chamber
(BooTH, 1979; CHANLEY & CHANLEY, 1970, 1980;
LeEBour, 1938; MorTON, 1972; NARCHI, 1969; OCKEL-
MANN & Muus, 1978; O FoIGHIL & G1BSON, 1984; OLD-
FIELD, 1964; PERES, 1937). TURNER & YAKOVLEV (1983)
describe a similar situation in the teredinid Zachsia zen-
kewitschi and propose that the presence of dwarf males in

Page 249

Table 1

Methods of bulk sperm transfer in galeommatacean
bivalves.

Species Method of sperm transfer

enclosed in “‘nutritive cells”
(OLDFIELD, 1961)

enclosed in “‘nutritive cells”
(OLDFIELD, 1961)

spermatophores (DEROUX, 1961)

Montacuta substriata (Mon-
tagu, 1808)

Montacuta (Tellimya) ferru-
ginosa (Montagu, 1808)

Mysella bidentata (Monta-
gu, 1803)

Pythinella cuneata (Verrilk
& Bush, 1898)

Pseudopythina subsinuata

Entovalva perriert (Malard,

enclosed in “elongate sacs”
(GAGE, 1968)

sperm morulae (MoRTON, 1972)

spermatophores (personal obser-

1903) vation)

Mysella tumida (Carpenter, | spermatophores (personal obser-
1864) vation)

Potidoma clarkiae (Clark, spermatophores (personal obser-
1852) vation)

Orobitella floridana dwarf males (JENNER & Mc-

CRARY, 1967)

dwarf males (JENNER & Mc-
Crary, 1967)

dwarf males (JENNER & Mc-
Crary, 1967)

dwarf males (MorTON, 1976)

temporary dwarf males (person-
al observation)

temporary complemental males?
(Morton, 1981)

complemental males? (DEROUX,
1960)

Montacuta percompressa
Entovalva sp.

Ephippodonta oedipus
Pseudopythina rugifera

Chlamydoconcha orcutti

Montacuta phascolionis

this species leads to a high percentage of the eggs being
fertilized. Likewise, dwarf males in Pseudopythina rugifera
and other galeommatacean species may optimize fertiliza-
tion success by getting sperm in large numbers to the
fertilization site.

An alternative method of bulk sperm transfer occurs in
a number of commensal galeommatacean species. This
usually entails the encapsulation of sperm masses within
nutritive cells, membranous envelopes, or bags, usually
called spermatophores (Table 1), which are subsequently
found attached to the gills of a conspecific (OLDFIELD,
1961; OCKELMANN & Muus, 1978; personal observation).
Although the details of spermatophore transfer have not
been revealed for most of these species, the spermato-
phores in Mysella tumida are released into the environ-
ment and taken back into the gill chamber, via the exhal-
ant opening (personal observation.).

Although both spermatophores and dwarf males achieve
sperm transfer between individuals, they differ in one im-
portant aspect—spermatophores have no inherent loco-
motory abilities and consequently are more restricted in
their dispersal ability, probably to conspecifics occurring
on the same host. Galeommatacean species with dwarf

Page 250

males have a planktonic larval stage (CHANLEY &
CHANLEY, 1970; MorTON, 1976) which, assuming some
of the larvae to be potential dwarf males, would result in
enhanced dispersal.

Spermatophores as a means of sperm transfer may be
more efficient than dwarf males where space restrictions
on or around the host does not normally prevent the co-
occurrence of equal-sized adult commensals. This pro-
posal is in accordance with ecological data provided by
GaGE (1966) for Montacuta substriata and Montacuta fer-
ruginosa, GAGE (1968) for Pythinella cuneata, OCKELMANN
& Muus (1978) for Mysella bidentata, and personal ob-
servations on Mysella tumida. A possible exception is En-
tovalva perriert, where individuals have been recorded to
occur singly on their holothurian hosts (POPHAM, 1940).

Commensal galeommataceans with dwarf males occur
attached to the host (JENNER & McCrary, 1968; CHANLEY
& CHANLEY, 1970; DALL, 1899), or in the case of the
Entovalva sp., in the tubes of the polychaete host (ABBOTT,
1974). Where space restrictions on or around the host
species may normally prevent the co-occurrence of equal-
sized adult commensals, and host distributions are dis-
crete, the dwarf male method may be the more effective
means through which sperm transfer is achieved. This
condition seems to be developing in Pseudopythina subsin-
uata, where the animals are restricted to a very specific
location, the last thoracic and first abdominal segments of
their stomatopod crustacean hosts (MORTON, 1972).
Stomatopods are considered to be territorial with non-
overlapping distributions (BROOKS, 1965). A similar sit-
uation may exist when P. rugifera occurs on Upogebia
pugettensis. The location of P. rugifera on this host is also
very restricted (DALL, 1899; Morton, 1972), and labo-
ratory observations suggest that U. pugettensis is territorial
(personal observation).

Pseudopythina rugifera also occurs as an ectocommensal
on the polychaete Aphrodita (MACGINITIE & MaAc-
GINITIE, 1968). Space restrictions on this host are not as
severe as on Upogebia pugettensis, and up to 13 specimens
may attach to one Aphrodita (personal observation). It
may be that U. pugettensis is the original host species for
P. rugifera and that dwarf males were evolved before
Aphrodita also became a host.

Differences in the two sperm transfer methods are not
absolute, as is best shown by Pseudopythina subsinuata.
Here, although a temporary dwarf male phase exists, the
males may be separate from the females and sperm are
transferred as morulae to the gills of the female (MorTON,
1972).

As mentioned in the Introduction, the dwarf males re-
ported by MorTON (1981) for Chlamydoconcha orcutti and
by DEROUx (1960) for Montacuta phascolionis occur in
association with larger, hermaphroditic individuals, and
may perhaps be better classified as complemental males.
This term refers to small males living in association with
large, hermaphroditic conspecifics. Use of this term im-
plies that these males are inherently incapable of devel-

The Veliger, Vol. 27, No. 3

oping into hermaphrodites (Hu1l & MoysE, 1984). It is
not clear whether the M. phascolionis are strictly comple-
mental, or are individuals that switch from the male con-
dition to simultaneous hermaphroditism as suggested by
JENNER & McCrary (1967). MORTON (1981) suggests
that, based on the structure of male and hermaphroditic
valves, the miniature males of C. orcutti eventually become
free-living and hermaphroditic.

Whatever the ultimate fate of the males in Montacuta
phascolionis and Chlamydoconcha orcutti, they are comple-
mental in function while they exist as males. The her-
maphroditic individuals may presumably outcross with
either the males or with other hermaphrodites. This sit-
uation would appear to combine the advantages of both
the dwarf male condition and spermatophore exchange
between equal-sized hermaphroditic adults, thus facilitat-
ing outcrossing in habitats with or without space restric-
tions. Complemental males, however, may face competi-
tion in transferring sperm to the host hermaphrodite from
neighboring hermaphrodites (CRispP, 1983). Dwarf males
only compete with each other in this respect. This suggests
that dwarf males are more stable over time than comple-
mental males.

Crisp (1983) proposes that dwarf males in the barnacle
Ibla cumingu (Ranzani) evolved by way of a complemental
male stage. Figure 9 depicts a hypothetical scheme outlin-
ing how a similar evolutionary pathway may have oc-
curred in the Galeommatacea, as a result of adaptation to
physically restricted habitats. In this scheme, condition A
is that of an outcrossing hermaphroditic species, where
the testis initiates development earlier than the ovary. This
hypothetical species occupies a diverse range of habitats,
including some where space restrictions may occur. BAREL
& KRAMERS (1977), OCKELMANN & Muus (1978), and
O FoIGHIL et al. (1984) describe essentially this situation
for Mysella bidentata. If over time, the species becomes
specialized for physically restrictive habitats, the mean
number of small individuals (predominantly male) per site
will increase relative to the number of larger hermaph-
rodites. Sperm transfer will increasingly be carried out by
the small males, which become complemental in function
(condition B). Montacuta phascolionis, as described by
PérEs (1937) and DEROUX (1960) seems an appropriate
example. Complemental males have an additional repro-
ductive advantage over the larger hermaphrodiies in the
relatively short amount of time required to achieve sexual
maturity (CRIsP, 1983). In M. phascolionis, the proportion
of testis to ovary in the hermaphroditic gonad is much
reduced relative to that of other Montacuta species
(DEROUX, 1960). Hermaphroditic individuals of barnacle
species with complemental males show a similar reduction
in the size of the testis, due to the lower reproductive
fitness of the male function in the hermaphrodite (CRISP,
1983). This trend should continue as habitats become yet
more restricted, until all sperm transfer is carried out by
the small males, and the larger individuals are female in
function (condition C). Pseudopythina rugifera belongs to

a aaa

D. O Foighil, 1985

Page 251

A B Cc

increasing increasing
space restrictions space restrictions

Figure 9

Hypothetical scheme for the indirect evolution of dwarf males
in the Galeommatacea by way of a complemental male stage. A,
hermaphrodites only; B, hermaphrodites and complemental males;
C, females and dwarf males.

this, the dwarf male category. Alternatively, as mentioned
above, dwarf males may evolve directly under similar en-
vironmental conditions, as a result of extreme protandry
(Morton, 1976).

The evolution of complex reproductive cycles in gale-
ommataceans was a prerequisite for the successful adop-
tion of a commensal mode of life (MoRTON, 1976). An
important step was the development of efficient modes of
sperm transfer (OCKELMANN & Muus, 1978). In some
species, including Pseudopythina rugifera, this involves the
use of dwarf males. Through the medium of dwarf males,
gene exchange may be facilitated between individuals that
are widely separated as a result of the space restrictions
and distribution patterns of their habitats. A more detailed
knowledge of the reproductive cycles and ecology of the
relevant species is needed to increase our comprehension
of the reproductive significance of dwarf males, spermato-
phores, and suspected complemental males in the Galeom-
matacea.

ACKNOWLEDGMENTS

My thanks to Louise Bickell, Megami Strathmann, Rich-
ard Strathmann, Dave Denning, Claudia Mills, Dave
Duggins, and Craig Staude for supplying specimens of
Pseudopythina rugifera. Earlier drafts were critically read
by Dr. A. R. Fontaine, Dr. R. G. B. Reid, Betsy Day,
Allan Gibson, and Richard Gustafson. Two anonymous
reviewers made useful comments. Dr. David McGrath
(University College Galway, Ireland) generously supplied
specimens of Entovalva perriert and Potidoma clarkiae. This
work was supported by a University of Victoria Graduate
Fellowship.

LITERATURE CITED

AsBoTT, R. T. 1974. American seashells. 2nd edition. Van
Nostrand Reinhold: New York. 663 pp.

BarEL, C. D. N. & P. G. N. Kramers. 1977. A survey of the
echinoderm associations of the North-East Atlantic area.
Zoologische Verhandelingen. 156 pp.

BooTtH, J. D. 1979. Common bivalve larvae from New Zea-
land: Leptonacea. N.Z. J. Mar. Freshwater Res. 13(2):241-
254.

Brooks, W. K. 1965. Pp. 83-84. In: W. L. Schmitt (auth.),
Crustaceans. University of Michigan Press: Ann Arbor.
CHANLEY, P. & M. H. CHANLEY. 1970. Larval development
of the commensal clam Montacuta percompressa Dall. Proc.

Malacol. Soc. Lond. 39:59-67.

CHANLEY, P. & M. H. CHANLEY. 1980. Reproductive biology
of Arthritica crassiformis and A. bifurca, two commensal bi-
valve molluscs. N.Z. J. Mar. Freshwater Res. 14(1):31-43.

Crisp, D. J. 1983. Chelonobia patula (Ranzani), a pointer to
the evolution of the complemental male. Mar. Biol. Lett. 4:
281-294.

Da.tL, W. H. 1899. Synopsis of the Recent and Tertiary Lep-
tonacea of North America and the West Indies. Proc. U.S.
Natl. Mus. 21:873-897.

Deroux, G. 1960. Formation réguliére de males murs, de
taille et d’organisation larvaire chez un Eulamellibranche
commensal (Montacuta phascolionis Dautz.). C. r. hebd.
Séanc. Acad. Sci. Paris 250:2264-22606.

DEROUX, G. 1961. Rapports taxonomiques d’un leptonacé non
décrit Lepton subtrigonum Jeffreys (nomen nudum-1873).
Cah. Biol. Mar. 2:99-153.

Franzen, A. 1970. Phylogenetic aspects of the morphology of
spermatozoa and spermatogenesis. Pp. 26-50. In: B. Bac-
cetti (ed.), Comparative spermatology. Acad. Naz. di Lincei:
Rome.

GaGE, J. D. 1966. Observations on the bivalves Montacuta
substriata and M. ferruginosa, commensals with spatangoids.
J. Mar. Biol. Assoc. U.K. 46:49-70.

GaGE, J. D. 1968. The mode of life of Mysella cuneata, a
bivalve commensal with Phascolion strombi (Sipunculoidea).
Can. J. Zool. 46:919-934.

GaGcE, J. D. 1979. Mode of life and behaviour of Montacuta
phascolionis, a bivalve commensal with the sipunculan Phas-
colion strombi. J. Mar Biol. Assoc. U.K. 59:635-657.

Hul, E. & J. Moyse. 1984. Complemental male in the prim-
itive balanomorph Chionelasmus darwini. J. Mar. Biol. As-
soc. U.K. 64:91-97.

JENNER, C. E. & A. B. McCrary. 1968. Sexual dimorphism
in erycinacean bivalves. Rep. Amer. Malacol. Union 35:43.

Lesour, M. V. 1938. The life history of Kellia suborbicularis.
J. Mar. Biol. Assoc. U.K. 22:447-451.

MacGInitig, G. E. & N. MACGINITIE. 1968. Natural history
of marine animals. 2nd edition. McGraw-Hill: New York.
523 pp.

Matera, E. M. & W. J. Davis. 1982. Paddle cilia (discocilia)
in chemosensitive structures of the gastropod mollusc Pleu-
robranchaea californica. Cell Tissue Res. 222:25-40.

Morton, B. 1972. Some aspects of the functional morphology
and biology of Pseudopythina subsinuata (Bivalvia: Lepto-
nacea) commensal on stomatopod crustaceans. J. Zool.
(Lond.) 166:79-96.

Morton, B. 1976. Secondary brooding of temporary dwarf
males in Ephippodonta (Ephippodontina) oedipus sp. nov.
(Bivalvia: Leptonacea). J. Conchol. 29:31-39.

Morton, B. 1981. The biology and functional morphology of
Chlamydoconcha orcutti with a discussion on the taxonomic
status of the Chlamydoconchacea (Mollusca: Bivalvia). J.
Zool. (Lond.) 195:81-121.

Narcul, W. 1969. On Pseudopythina rugifera (Carpenter, 1864)
(Bivalvia). Veliger 12(1):43-52.

OCKELMANN, K. W. & K. Muus. 1978. The biology, ecology
and behaviour of the bivalve Mysella bidentata (Montagu).
Ophelia 17(1):1-93.

O FoicHit, D. & A. W. Gipson. 1984. The morphology,
reproduction and ecology of Scintillona bellerophon spec. nov.
(Galeommatacea). Veliger 27(1):72-80.

Page 252

The Veliger, Vol. 27, No. 3

O FoicuiL, D., D. McGratu, M. E. ConneEELY, B. F. KEEGAN
& M. CosTELLOE. 1984. Population dynamics and repro-
duction of Mysella bidentata (Bivalvia: Galeommatacea) in
Galway Bay, Irish West coast. Mar. Biol. 81:283-291.

OLDFIELD, E. 1961. The functional morphology of Kellia sub-
orbicularis (Montagu), Montacuta ferruginosa and M. sub-
striata (Montagu), (Mollusca, Lamellibranchiata). Proc.
Malacol. Soc. Lond. 34:255-295.

OLDFIELD, E. 1964. The reproduction and development of
some members of the Erycinidae and Montacutidae (Mol-
lusca, Eulamellibranchiata). Proc. Malacol. Soc. Lond. 36:
79-120.

Pérés, J. M. 1937. Sur trois espéces du genre Montacuta (Kel-
lyidae). Trav. Stn. Biol. Roscoff 15:5-28.

PETTIBONE, M. H. 1953. Some scale-bearing polychaetes of
Puget Sound and adjacent waters. University of Washington
Press: Seattle. 89 pp.

PopHaM, M. L. 1940. The mantle cavity of some of the Ery-
cinidae, Montacutidae and Galeommatidae with special ref-

erence to the ciliary mechanisms. J. Mar. Biol. Assoc. U.K.
24:549-587.

Rep, R. G. B. & S. P. Crossy. 1980. The raptorial siphonal
apparatus of the carnivorous septibranch Cardiomya plane-
tica Dall (Mollusca: Bivalvia), with notes on feeding and
digestion. Can. J. Zool. 58(4):670-679.

ROSEWATER, J. 1984. A new species of leptonacean bivalve
from off northwestern Peru (Heterodonta: Veneroidea: La-
saeidae). Veliger 27(1):81-89.

SmiTH, T. B. 1983. Tentacular ultrastructure and feeding be-
haviour of Neopentadactyla mixta (Holothuroidea: Dendro-
chirota). J. Mar. Biol. Assoc. U.K. 63:301-311.

STASEK, C. R. 1962. Aspects of ctenidial feeding in immature
bivalves. Veliger 5:78-79.

TAMARIN, A., P. Lewis & J. ASKEY. 1974. Specialized cilia of
the byssus attachment plaque forming region in Mytilus cal-
ifornianus. J. Morphol. 142:321-328.

TURNER, R. D. & Y. YAKOVLEV. 1983. Dwarf males in the
Teredinidae (Bivalvia, Pholadacea). Science 219:1077-1078.

THE VELIGER

© CMS, Inc., 1985
The Veliger 27(3):253-260 ( January 2, 1985)

Life-habits and Infaunal Posture of
Cumingia tellinoides (Tellinacea, Semelidae):
An Example of Evolutionary Parallelism
by

W. D. RUSSELL-HUNTER anpb JAY S. TASHIRO!

Marine Biological Laboratory, Woods Hole, Massachusetts 02543, and
Department of Biology, Syracuse University, Syracuse, New York 13210

Abstract. The semelid clam Cumingia tellinoides is an infaunal burrowing form found in sandy
organic deposits. Its eggs have been used in experimental embryology for over 80 years, and it has
usually been reported to have a vertical life-posture and a “nearly equivalve” shell. In populations
from the Cape Cod area, the majority of individuals live and feed while lying horizontally within the
sediment and show asymmetries of shell structure. Observations and photographs of movements and
feeding postures were made possible by use of artificial substrates prepared from cryolite.

There is considerable individual plasticity of behavior and shell variation in Cumingia tellinoides. For
all field and laboratory observations, 76.1% of individual clams were found lying on one shell valve
(and in 78.4% of these it was the left valve down). Some corresponding deformation of the posterior
shell margins was found in 79.2%, and in 42.9% this amounted to a clear lateral twist (in 65.4% of
these to the right, or posturally upwards). Internal asymmetries of the pallial sinus were found in
60.8% of shell valve pairs, and there was a significant (P < 0.05) inverse correlation between lateral
twist direction and larger sinus scar areas in Cumingza tellinoides. In contrast, in the sympatric tellinid
clam Macoma tenta, all were found lying on their left valves, all shells showed a right-handed twist,
and 93.7% had a larger area in the left pallial sinus.

The pattern of horizontal feeding posture, associated with posterior twisting and asymmetric pallial
lines in the shell valves, appears to be variably expressed in Cumingza tellinoides, contrasting with
similar but obligate features in Macoma tenta. It seems most probable that the occurrences of horizontal
life-style (and associated asymmetries of shell and muscles) in both semelid and tellinid lineages con-
stitute an example of evolutionary parallelism rather than of evolutionary convergence.

INTRODUCTION right) of the posterior margins of their shell valves. Earlier
surveys of the life-habitats of such infaunal bivalves
(STANLEY, 1970; ABBOTT, 1974) claimed a vertical life-
posture and a “nearly equivalve” shell for Cumingia.
We now report that, in Cumingia tellinoides, the major-
ity of individuals live and feed while buried nearly hori-
zontally in the sediment, and many show not only a slight
posterior twist to the shell valves but also an internal
asymmetry of the scars of the pallial sinus (that is, of the
attachment of the siphonal retractor muscles to the shell
valves). Use of artificial deposits made from the pure min-
eral cryolite allowed us to obtain photographs of living
specimens of C. tellinoides in their feeding posture within

LITTLE HAS BEEN published on the natural history of the
semelid clam Cumingia tellinoides Conrad despite exten-
sive laboratory use of its eggs as material for experimental
embryology for over 80 years. In general, within the bur-
rowing and infaunal superfamilies of lamellibranchs, an
inequivalve condition of the bivalve shell is associated with
a non-vertical posture in the substrate. More than half of
the species in the Tellinidae, and a number of species in
the Semelidae, are known to have a twist (usually to the

‘Present address: Department of Biology, Kenyon College,
Gambier, Ohio 43022.

the substrate (some reproduced here). These observations
and results are discussed in relation to other molluscan

Page 254

examples of parallelism and convergence in adaptation.
Critical assessment of cladistic systematics has re-empha-
sized the need for discrimination between convergence and
parallelism (Mayr, 1974), and this is partly responsible
for a revival of interest in such evolutionary distinctions
at all levels of biological organization.

MATERIALS anp METHODS

In the Cape Cod area, Cumingia tellinoides lives in sandy
organic deposits associated with eelgrass (Zostera), around
the level of MLWST and for about 20 cm deeper. More
specifically, it is found in fine sand with a high fraction
of peaty material and sometimes even among eelgrass roots,
not usually under the densest beds of Zostera, but rather
where there are sparser clumps of eelgrass along the mar-
gins of the little channels that drain the flats during the
lowest tides (GRAVE, 1927; and author’s observations).
Healthy specimens used for measurement and photogra-
phy were collected on various occasions between 1973 and
1981 from an area of flats in the Northwest Gutter of
Hadley Harbor (in the Elizabeth Islands, near Woods
Hole). Populations of C. tellinoides have also been exam-
ined in the other gutters of the Hadley system, and in
similar microhabitats in the tidal harbors of North Fal-
mouth, Quisset and Orleans, all on Cape Cod. From
about 1907 to 1927, C. tellinoides was collected regularly
and intensively to provide eggs for embryologists and cell-
physiologists (including H. E. Jordan, E. G. Conklin, F.
R. Lillie, E. Browne-Harvey, B. H. Grave, T. H. Mor-
gan, and L. V. Heilbrunn) working in the Marine Bio-
logical Laboratory at Woods Hole. It apparently became
a very rare species with the decline of eelgrass beds be-
tween 1930 and 1960, but was listed normally and not
marked as “rare” in a faunal key prepared in 1963
(RUSSELL HUNTER & BROWN, 1964). It is now (1980-
83) not uncommon again, although limited to certain lo-
calities and to the highly specific microhabitat described
above.

The family Semelidae, in which the genus Cumingia is
placed along with Semele and Abra, can be separated from
the family Tellinidae (including Tellina and Macoma) by
major differences in the functional shell ligament and in
hinge dentition. These features of shell morphology will
be discussed more fully below, but it should be noted that
Cumingia (like all semelids) has an internal resilium (car-
ried on a chondrophore plate) as its functional shell lig-
ament, while all tellinids, including those local species of
Macoma which can be nearly sympatric (Macoma tenta
and M. balthica), have elongate external ligaments.

Observations and photographs of the movements and
feeding posture of Cumingia tellinoides within the sub-
strate were made using artificial deposits ground and sieved
to size from large pure crystals of the mineral cryolite,
which has a refractive index close to that of seawater.
Biological application of this material was first described
by JOSEPHSON & FLEssA (1971, 1972), and its use for

The Veliger; Vol} 275 Noss

these studies on Cumingia reported in an abstract
(RUSSELL-HUNTER & TASHIRO, 1973). Cryolite media are
better suited for invertebrates such as Cumingia that live
in sand deposits, being more resistant to penetration than
are those prepared from methylcellulose (HUNTER, 1982;
HUNTER et al., 1983) which are better for worms from
flocculent mud deposits. When suitably illuminated, gran-
ular cryolite in seawater is relatively “transparent,” per-
mitting close observations of pedal and siphonal move-
ments within the substrate and allowing photography at
moderately high resolution.

Each experimental aquarium was prepared by clamp-
ing two sheets of plate glass (approximately 20 cm square)
around a piece of thick-walled rubber hose (of 1.5 or 2.8
cm outside diameter) bent into a U-shape, and filling the
U to a depth of 8 to 10 cm with field-collected natural
substrate or with ground cryolite in about 15 cm of sea-
water. Photographs were taken with a 105-mm lens and
bellows on a Bronica (6 cm square) camera, using Kodak
Plus-X film rated at ASA 210 and developed in half-
strength Acufine. Most photographs were taken with both
front (direct) and back (transmitted) lighting of the sub-
strate. The results (see Figures 1, 4, 6) show edge defi-
nition and resolution somewhat better than those achieved
using X-radiography by STANLEY (1970) in the course of
his heroic survey of the life habits of 98 extant bivalve
species.

OBSERVATIONS anD RESULTS

During the summers from 1961 to 1972, the frequency
with which Cumingza tellinoides appeared in field collec-
tions of the Invertebrate Zoology course at Woods Hole
increased. In 1967 and 1968, casual inspection of samples
totaling about 25 animals each year revealed that the ma-
jority showed some deformation of the posterior margins
of the shell valves, with many showing a definite posterior
twist as in Figure 3. Casual observations of live C. telli-
nodes in the same two years showed that the majority lay
on one side in the sediment as did the more abundant
Macoma tenta.

There is obviously some individual plasticity of behav-
ior in Cumingia tellinoides. During a more intensive study
in 1973, in the course of several burrowing experiments,
a total of 51 specimens was left each for just over 48 h in
dishes with about 6 cm depth of natural sediments freshly
collected from the field. To describe orientation, we can
use the sagittal plane of each individual clam (that is, the
plane defined by both the anterio-posterior and dorso-
ventral axes which, in symmetrical bivalves, is also the
plane where the edges of the shell valves meet on adduc-
tion). Of the 51, 7 (13.7%) had their sagittal planes ver-
tical and thus could be actively burrowing, while 5 (10%)
had their sagittal planes at about 45° to the surface of the
sediment. The majority (39/51 or 76.5%) lay with their
sagittal planes nearly horizontal (that is, parallel to the
sediment surface). Shell-lengths of this group ranged from

W. D. Russell-Hunter & J. S. Tashiro, 1985

9.0 to 17.8 mm (mean 12.6 mm) and, for those lying
horizontal in the sediment, the average depth of burial
was about 15 mm or just over one shell-length. In the
field, living specimens of C. tellinoides are usually found
buried at depths of about twice their individual shell-
lengths. For 16 specimens carefully uncovered by finger
in the field, none had vertical sagittal planes, and only 4
approached 45° from the horizontal. Both in the labora-
tory dishes and in the field, most horizontal specimens of
C. tellinoides lay on their left side, but a few lay on their
right (see shell proportions below). This contrasts with
conditions in adjacent populations of the tellinid Macoma
tenta where the feeding posture of every individual is lying
on its left valve (which is somewhat more convex).

Many tellinids, which take up a horizontal feeding pos-
ture within the substrate, burrow relatively rapidly from
the surface with their sagittal planes at a low angle from
the horizontal (HOLME, 1961; STANLEY, 1970). For each
species studied in detail, an obligate orientation has been
reported. In contrast, individuals of Cumuingia tellinoides
burrow rather slowly, and enter both natural sediments
and cryolite deposits with their sagittal planes at a slight
angle to the vertical (Figures 1, 2). The dorsal or hinge
side is characteristically lower, but the slight lateral in-
clination that is normal may be to either the left or the
right side. Burrowing is essentially similar to that in un-
specialized and more globose bivalves (ANSELL & TRUE-
MAN, 1967; TRUEMAN, 1968; TRUEMAN et al., 1966), with
alternate points dappui being provided by the opening
gape of the shell valves and the dilatable foot. Some feed-
ing can go on during parts of the burrowing cycle (Figure
1). At a depth corresponding to shell length, the lateral
inclination increases and the sedentary posture (nearly
horizontal) is taken up. Figures 4, 5, and 6 show speci-
mens with siphons extended for feeding. Once this posture
is established the foot is rarely extended, and it is likely
that, in the peaty sand substrates of the field, C. tellinoides
does not move much once established in the substrate. A
number of earlier authors including STANLEY (1970) have
claimed a vertical posture for C. tellinoides when feeding,
and one X-radiograph in his survey shows four specimens
all anterior down and vertical with siphons extended in
feeding, with channels in the substrate revealing former
siphon positions. It seems possible that the individual
plasticity of behavior (including infaunal posture) in C.
tellinoides could involve different norms for different pop-
ulations, perhaps with some relation to different substrate
conditions.

In all of our observations (including the clams of Fig-
ures 4, 5, and 6) the inhalant (ventral) siphon was directed
nearly vertically and was used in both suspension and
deposit-feeding, while the exhalant (dorsal) siphon dis-
charged below the surface or reached it at an obtuse angle
at least 10 mm away from the inhalant. With healthy
animals in cryolite deposits, it is easy to distinguish the
small spherical fecal pellets and the larger, somewhat less
consolidated, masses of pseudofeces as they move within

Page 255

the extended siphons. Only true feces are discharged
through the exhalant siphon, they pass slowly but regu-
larly into the substrate, either (Figure 4) close to the dor-
so-posterior shell margin with little siphonal extension, or
(Figures 5, 6) in a wide arc posteriorly and upward. Sim-
ilar discharge of the exhalant siphon within the substrate
has been reported for the tellinids Macoma nasuta
(MacGINITIE, 1935) and Arcopagia crassa (HOLME, 1961).
At irregular intervals the larger softer masses of pseudo-
feces are shot vertically up the inhalant siphon high above
the sediment surface (as a result of partial valve adduc-
tion). [It should be noted that, in Figure 4, a fecal pellet
shown halfway to the surface is not inside the inhalant
siphon.] More frequent discharge of pseudofeces (in some-
what larger, looser masses) occurs during periods of de-
posit-feeding. This flexibility of feeding behavior found in
Cumingia tellinoides is probably unusual in semelid and
tellinid bivalves since most investigators (YONGE, 1949;
Ho.LME, 1961; STANLEY, 1970; ABBOTT, 1974) suggest
that each species in these two families is either a suspen-
sion feeder or a deposit-feeder. However, BRAFIELD &
NEWELL (1961) have claimed that certain British popu-
lations of Macoma balthica show tidally controlled alter-
nation of suspension- and deposit-feeding. For the same
species in Denmark, RASMUSSEN (1973) has illustrated
both feeding modes. However, GILBERT (1977) regards it
as an obligatory deposit feeder, while TUNNICLIFFE &
RIsk (1977) conclude that it must supplement its protein
intake by suspension-feeding when submerged.

Figure 7 is a vertical photograph of the inhalant siphon
of a specimen of Cumingia tellinoides living in natural
substrate and engaged in deposit-feeding. Despite the
quality of the photograph (poor contrast, and little depth
of focus), some radiating marks can be detected on the
surface of the sediment. These are in conformity with our
observations that, during deposit-feeding the recurved in-
halant siphon of C. tellinoides is not swept in a circular
path as is the case in most deposit-feeding tellinids (YONGE,
1949; HoLME, 1950, 1961; STANLEY, 1970), but sucks in
a series of radial skimming movements directed centrip-
etally (like Macoma tenta; STANLEY, 1970). Rejection of
pseudofeces commonly occurs after each group of three or
four radial sweeps.

Three collections of Cumingia tellinoides totaling 79 in-
dividuals were used to quantify shell variation. Most of
these were killed by immersion in hot water and subse-
quent removal of the soft tissues, but 17 clams had initially
been fixed in formalin. Of the total, 2 were damaged in
preparation and 3 others were too small for assessment of
the pallial sinus, so that shell features are reported for 77
shell-valve pairs (or 74 pairs for sinus asymmetries). Some
deformation of the posterior part of the shell was found
in one or both valves of 61/77 or 79.2%, and this amount-
ed to a clear twist (as in Figure 3) in 33/77 or 42.9%. In
a few cases, a twist to the left had been preceded by a
twist to the right, or vice versa, and in two sets of valve
pairs a series of alternate “twists” seemed to have oc-

Page 256

The Veliger, Vol. 27, No. 3

curred. Of these with a single clear twist, 9/26 turned left
while 17/26 turned right. This figure of 65.4% with the
posterior shell margins turned right (corresponding to
growth during a sedentary period of infaunal posture lying
on the left valve) is considerably less than the figure of
78.4% for clams found alive lying on their left valves (as
a percentage of the combined numbers for all live field
and laboratory observations found lying horizontally,
which amounted in turn to 76.1% of all observations). In
other words, although left valve down occurs in a majority
(59.7%) of our live observations, the corresponding shell
twist is found only in a plurality (22% single clear, or
28.6% total) of shell pairs studied.

Another asymmetry shown by the shell-valve pairs,
which may be of considerable functional importance, con-
cerns modification of the internal attachment of the si-
phonal retractor muscles. These so-called pallial sinus scars
form embayments of the pallial lines, which elsewhere run
concentric with the shell margins and mark the insertion
in the nacreous layer of the shell for the line of muscles
from the innermost of the three lobes of the mantle edge.
Asymmetries between left and right shell-valves of the
pallial sinus scars can involve (a) the areas enclosed by
the scars (reflecting the “spread” of the muscle attach-
ments), (b) the width of the scar lines (reflecting the thick-
ness of the attached muscle sheet), or (c) the shape of the
sinus embayment ranging from broadly ovate to triangu-
lar. This third kind of asymmetry is less easily quantified.
One or more of these three asymmetries were found in
45/74 or 60.8% of the shell-valve pairs. Once again there
were biases of orientation but no uniformity of handed-
ness. The scar area was larger in 19 left valves and in 14
right valves, and the scar was more pronounced in 8 left
valves and in 14 right valves. There was a tendency for

those shells with the posterior margins twisted to the right
(being the plurality) to show larger scar areas in the left
valve and more pronounced scar lines in the right valve,
while the shells with a left-handed twist (the minority)
tended to show the opposite conditions. In a 3 x 3 con-
tingency table, there was a significant inverse correlation
between marginal twist direction and larger sinus scar
areas (summed chi-squares = 10.667, df 4, P < 0.05). For
comparison, in a sample of Macoma tenta totaling 63 in-
dividuals, all shells showed a right-handed twist which
could involve more than one third of the length of the
shell, and 59/63 or 93.7% showed a larger pallial sinus
area in the left valve. Clearly in Cumingza tellinoides those
shell asymmetries related to infaunal posture show levels
of individual variation that parallel the individual plastic-
ity of behavior.

DISCUSSION

The fact that Cumingia tellinoides is found in a marginal
microhabitat is relevant to any discussion of the variable
behavior exhibited by individuals and of the related asym-
metries of their shells.

Two principal life-styles are found in the bivalve sub-
order or superfamily Tellinacea. Some species and genera
show a capacity for rapid reburrowing associated with
symmetrical, streamlined, smooth shells, and those may
live in shifting substrata or move laterally in a near hor-
izontal orientation in the course of deposit-feeding (HOLME,
1961; STANLEY, 1970). Other, often closely related, species
are less typically members of the mobile “superficial in-
fauna,” seem adapted for a more permanently sedentary
way of life, and may live in peaty deposits or among the
root systems of eelgrass (Zostera) or turtle-grass (Thalas-

Explanation of Figures 1 to 7

Figure 1. An early stage in burrowing in an adult specimen of Cumingza tellinoides (12.8 mm shell length), with
some feeding continuing through the open siphons. The photograph was made in an artificial deposit of ground
and sieved crystalline cryolite (as were Figures 2, 4, 5, and 6).

Figure 2. The same clam as in Figure 1 a few seconds later, with the dilatable foot being extended and the siphons
closed.

Figure 3. Dorsal view of the posterior margins in an adult shell of Cumingza tellinoides. The right shell valve is
above, and the scale-bar equals 1 mm.

Figure 4. Sedentary feeding posture of an adult specimen of Cuningia tellinoides (13.3 mm), photographed in
cryolite with the dorsal (hinge) side toward the camera, showing the inhalant siphon extending vertically to the
surface. [Note that the fecal pellet halfway to the surface is not inside the siphon. ]

Figure 5. Feeding posture in another (11.9 mm) specimen viewed from the ventral side. Three fecal pellets have
been deposited by the downturned exhalant siphon close to the posterior shell margin.

Figure 6. Ventral view of the feeding posture in another (14.6 mm) specimen. This clam is engaged in suspension-
feeding rather than deposit-feeding. Fecal pellets have been deposited in an arc up to the surface of the deposit by
the exhalant siphon which is extended horizontally in the photograph.

Figure 7. Vertical photograph of the inhalant siphon of a specimen of Cumingia tellinoides living in natural substrate.
The faint radial marks to the right of the siphon represent tracks of recent inhalant passes during deposit-feeding.
The scale-bar equals 2 mm.

W. D. Russell-Hunter & J. S. Tashiro, 1985 Page 257

Page 258

sta). Despite statements by some authors, there is no uni-
versal correlation of the first life-style with deposit-feeding
and the second with suspension-feeding. Asymmetries of
the shell valves of adults (including the posterior marginal
twist, and inequalities of the pallial sinus) are clearly
associated with a horizontal infaunal habit (7.e., lying on
one shell valve), and increased functional efficiency in that
posture. However, it now appears that either life-style
(rapid-reburrowing or sedentary) may be associated with
a horizontal infaunal posture. Further, the results from
this study of Cumuingia tellinoides demonstrate that great
individual shell variation and plasticity of behavior are
possible within a species.

Features common to the four families of the Tellinacea
include separate long extensible siphons, a blade-like foot
for burrowing, a pallial cruciform muscle (GRAHAM, 1934;
YONGE, 1949, 1957), and rather large labial palps. Dur-
ing deposit-feeding, the palps are used for sorting the de-
tritus which is sucked in from the surface by a vacuum-
cleaner-like action of the inhalant siphon (Figure 7).
Within the superfamily, two of the families, the Tellini-
dae, to which the genera TJellina and Macoma belong, and
the Semelidae, to which Semele, Abra, and Cumingia be-
long, can be separated by major differences of the func-
tional ligament and hinge dentition. The tellinids have an
elongate external ligament with rather weak teeth, while
the semelids have an internal resilium as the functional
ligament (carried on a chondrophore plate rather like that
of Mya), and strong cardinal and lateral hinge-teeth. These
are features regarded as phyletically sound and as genet-
ically conservative by most systematists and paleontolo-
gists. This assessment need not be modified by the obser-
vations of TTRUEMAN (1953, 1966) which suggest that the
larger internal ligament of the semelids is homologous
with the tiny cardinal ligament present temporarily in
juveniles (spat) of some tellinids (Macoma and Tellina),
and is therefore neotenic.

Cumingia tellinoides is frequently found living with Ma-
coma tenta (although M. tenta is more widely found alone
in bare muddy sands 3-8 m below MLWST). The habit
of lying on one side in the sediment (as done by both
species) and the structural asymmetries associated with
the habit, must have evolved independently in semelids
and tellinids. There are a number of other well-estab-
lished cases of ecologically sympatric pairs of species de-
rived from morphologically distinct stocks of bivalves. As
discussed by MAyR (1969, 1974) and Bock (1963, 1965)
it is often difficult to distinguish cases of major evolution-
ary convergence from similarities in allied stocks which
result from parallelism. Among bivalves, striking similar-
ities of shell structure and muscle mechanics can be found
in sympatric forms derived from widely different super-
families—for example, fused-siphon deep-burrowers from
both Myacea and Mactracea, globose ribbed cockles from
Cardiacea and Arcacea, and borers in soft rock (Hiatella,
Petricola, and Zirphaea) from three distinct superfamilies.
These are almost certainly all cases of evolutionary con-

The Veliger, Volz27- iow

vergence as distinguished by Mayr (1969, 1974), as are
the many and polyphyletic stocks of limpetlike gastropods
(RUSSELL-HUNTER, 1982).

With the common features of infaunal posture and shell
modification in Macoma and Cumingia, however, we may
be observing the results of parallelism, or similarities of
structure and function produced by shared genotypic fea-
tures (not expressed in this combination in other related
forms). In this view, some of the other features noted
above as common to the overall group, the Tellinacea, are
of paramount importance. These include the cruciform
muscle (YONGE, 1949, 1957; see also GRAHAM, 1934),
which may be involved in adjusting the basal attitude of
the siphons, and also the mode of extension of the siphons
(CHAPMAN & NEWELL, 1956; see also CHAPMAN, 1958)
using radial muscles within the siphonal walls, so that
water circulation and feeding can go on during a smooth
and continuous process of protrusion. This is totally un-
like the mechanism of siphonal extension employed in
Hratella (RUSSELL HUNTER, 1949) and in Mya (CHap-
MAN & NEWELL, 1956) where protrusion occurs in step-
wise stages involving closed siphonal tips and serial con-
tractions of the shell adductor muscles. Along with these
features common to the shared superfamily, the tellinid
Macoma and the semelid Cumingia both exhibit structural
features, such as the posterior shell twist and asymmetries
of the pallial sinus, which may be correlates of a horizon-
tal infaunal posture. Evolutionary hypotheses regarding
such correlates must be based on analyses of function, and
of adaptive significance, as clearly articulated by Bock
(1965, see also BocK & VON WAHLERT, 1965) in discuss-
ing similar vertebrate cases. In considering all bivalve
species in the Tellinacea (or all individuals in a variable
species like Cumingza tellinoides), it is important to note
that these correlates of structure with behavior are not
reciprocal. All twisted shells occur in species (or individ-
uals) that live in a horizontal infaunal posture, but not all
forms living horizontally have shell twists.

The functional significance of the shell twist is clearly
related to its molding of the siphonal bases and to the
hydraulics of water circulation in feeding. MACGINITIE
(1935) provided the earliest description of the implications
of the horizontal posture for feeding behavior in Macoma
nasuta, and this was built upon by HOLME (1961) in his
observations on five British tellinid species with this life-
style. It was left to STANLEY (1970) to illustrate and dis-
cuss the fact that an upward twist of the posterior valve
margins (where the siphons emerge from the shell) serves
to broaden the radius of siphonal curvature and streamline
water flow. This can be seen in Figures 4 and 6, and it
is obviously more important to the inhalant siphon with
its near vertical orientation. Our observations on Cumin-
gia tellinoides in cryolite confirm Stanley’s functional anal-
ysis, but add the necessary discharge of pseudofeces through
the inhalant siphon as a factor favoring streamlining of
the bend in that siphon at the shell margin. As already
noted, in the sympatric form Macoma tenta all individuals

W. D. Russell-Hunter & J. S. Tashiro, 1985

lie horizontally on their left valves, and all show a right-
handed posterior twist, which can extend over one-third
of the length of the shell. [There is an intriguing possi-
bility that mirror-image races of M. tenta may exist, be-
cause ABBOTT (1974) gives as specific characteristics ‘““pos-
terior and narrower end slightly twisted to the left.’’]
However, unlike the variable conditions found in C. tel-
linoides, curvature of the shell in M. tenta is universal and
seems to result from an obligate growth pattern which
continues through most of adult life and results in the left
valve being somewhat more convex than the right. This
is carried even further in another bizarre tellinid, Telli-
dora cristata, which has an almost “‘oyster-like” arrange-
ment of a flat left valve and a bowl-shaped right valve.
Unfortunately, nothing is known about life-habits in 7.
cristata.

Two distinct life-styles have been associated with the
horizontal infaunal posture. In active species like Tellina
tenuis and T. agilis, HOLME (1961) and STANLEY (1970)
claim that the horizontal posture facilitates lateral move-
ments in the substrate within a single plane, thus main-
taining an even depth of burial. In contrast, in some species
of Macoma and in Cumingia tellinoides the horizontal pos-
ture is associated with more permanently immobile feed-
ing habits and a relatively sedentary life-style. This is also
the case for Semele proficua, which has a symmetrical dis-
coid shell but lives horizontally on its left side among roots
of Thalassia, and could also be predicted as the life-style
of the extremely asymmetric Tellidora. To further com-
plicate matters, several species of Macoma with marked
asymmetry of the pallial sinus have no shell twist and
have been listed in most general accounts (along with C.
tellinoides) as having a vertical life posture and near equi-
valve shells. General surveys of fossil faunas of bivalves
show a majority of species to be infaunal (NICOL, 1968),
and inequivalve representatives to occur in at least 28
families (NICOL, 1958; see also NEWELL & MERCHANT,
1939), but reveal no regularities of habit.

Given the variety of associations listed above for the
Tellinacea, it seems most probable that the occurrences of
horizontal life-style (and associated asymmetries of shell
and muscles) in both tellinid and semelid lineages consti-
tute an example of evolutionary parallelism. Although it
makes no reference to shared genotypic features, an early
definition by SIMPSON (1961) remains valid: “parallelism
is the independent occurrence of similar changes in groups
from a common ancestry and because they had a common
ancestry.” An earlier discussion of parallel adaptations in
related stocks was set out by RENSCH (1943) along with
other germinal ideas about evolution above the species
level, and OscHE (1965) gives more detailed analyses of
the potentialities of “hidden” gene combinations. The im-
portance of attempting to discriminate between evolution-
ary convergence and parallelism has been re-emphasized
in the course of a critique of cladistic systematics (MAyYR,
1974), and in relation to the debate on molluscan evidence
for punctuated equilibria in evolutionary lineages (Mayr,

Page 259

1982). The present example of parallelism provided by
the pattern of variably expressed behavior and shell mor-
phology in the semelid Cumingia tellinoides, and of similar
but obligate features in the tellinid Macoma tenta, may
permit future experimental investigation. Meanwhile, use
of such features as asymmetry of the pallial sinus to de-
duce life-style or infaunal posture in stocks of fossil or
extant bivalves is questionable.

ACKNOWLEDGMENTS

It is a pleasure to thank John J. Valois, the manager of
the marine resources department of the Marine Biological
Laboratory, who not only aided us with boat transport to
Northwest Gutter, but later confirmed, from his wide
knowledge of the distribution of invertebrates in Cape
waters, both our summary of the history of local abun-
dance of Cumingia tellinoides and our description of its
microhabitat. We are also grateful to boat captain Dick-
son A. Smith for collecting the comparative population
sample of Macoma tenta. We must again thank Perry Rus-
sell-Hunter for assistance with reference material, and
Barbara J. Carns and Myra Russell-Hunter for help in
the preparation of this paper. The work was partly sup-
ported by a faculty research award to Jay S. Tashiro from
Kenyon College, and a research grant DEB-78-10190 from
the National Science Foundation to W. D. Russell-
Hunter.

LITERATURE CITED

AsBoTT, R. T. 1974. American seashells. 2nd edition. Van
Nostrand Reinhold Company: New York. 663 pp.

ANSELL, A. D. & E. R. TRUEMAN. 1967. Burrowing in Mer-
cenaria mercenaria (L.) (Bivalvia, Veneridae). J. Exp. Biol.
46:105-115.

Bock, W. [J.] 1963. Evolution and phylogeny in morpholog-
ically uniform groups. Amer. Natur. 97:265-285.

Bock, W. [J.] 1965. The role of adaptive mechanisms in the
origin of higher levels of organization. Syst. Zool. 14:272-
287.

Bock, W. J. & G. VON WAHLERT. 1965. Adaptation and form-
function complex. Evolution 19:269-299.

BRAFIELD, A. D. & G. E. NEWELL. 1961. The behaviour of
Macoma balthica (L.). J. Mar. Biol. Assoc. U.K. 41:81-87.

CHAPMAN, G. 1958. The hydrostatic skeleton in the inverte-
brates. Biol. Rev. 33:338-371.

CuapmMan, G. & G. E. NEWELL. 1956. The role of the body
fluid in the movement of soft-bodied invertebrates. II. The
extension of the siphons of Mya arenaria L. and Scrobicularia
plana (da Costa). Proc. Roy. Soc. Lond., series B 145:564-
580.

GILBERT, M. A. 1977. The behaviour and functional mor-
phology of deposit feeding in Macoma balthica (Linné, 1758),
in New England. J. Moll. Studies 43:18-27.

GRAHAM, A. 1934. The cruciform muscle of lamellibranchs.
Proc. Roy. Soc. Edinburgh 54:17-30.

Grave, B. H. 1927. The natural history of Cumingia telli-
noides. Biol. Bull. 53:208-219.

Home, N. A. 1950. Population-dispersion in Tellina tenuis
da Costa. J. Mar. Biol. Assoc. U.K. 29:267-280.

Home, N. A. 1961. Notes on the mode of life of the Tellin-

Page 260

The Veliger; Vol. 27 Noss

idae (Lamellibranchia). J. Mar. Biol. Assoc. U.K. 41:699-
703.

Hunter, R. D. 1982. Methylcellulose: an alternative medium
for the study of burrowing aquatic invertebrates. Mar. Be-
hav. Physiol. 8:199-203.

Hunter, R. D., V. A. Morris & H. Y. ELDER. 1983. Image
analysis of the burrowing mechanisms of Polyphysia crassa
(Annelida:Polychaeta) and Priapulus caudatus (Priapulida).
J. Zool. 199:305-323.

JosEpHsON, R. K. & K. W. FLessa. 1971. Cryolite: a new
technique for observing burrowing in aquatic animals. Biol.
Bull. 141:392.

JOsEPHSON, R. K. & K. W. FLessa. 1972. Cryolite: a medium
for the study of burrowing aquatic organisms. Limnol.
Oceanogr. 17:134-135.

MacGiniti£, G. E. 1935. Ecological aspects of a California
marine estuary. Amer. Midl. Natur. 16:629-765.

Mayr, E. 1969. Principles of systematic zoology. McGraw-
Hill: New York. 428 pp.

Mayr, E. 1974. Cladistic analysis or cladistic classification.
Zeitsch. Zool. Syst. Evol. (Frankfurt) 12:94-128.

Mayr, E. 1982. Questions concerning speciation. Nature 296:
609.

NEWELL, N. D. & F. E. MERCHANT. 1939. Discordant valves
in pleurothetic pelecypods. Amer. J. Sci. 237:175-177.
Nicot, D. 1958. A survey of inequivalve pelecypods. J. Wash.

Acad. Sci. 48:56-62.

Nico., D. 1968. Are pelecypods primarily infaunal animals?
Nautilus 82:37-43.

OscHE, G. 1965. Uber latente Potenzen und ihre Rolle im
Evolutionsgeschehen. Zool. Anzeiger 174:411-440.

RASMUSSEN, E. 1973. Systematics and ecology of the Isefjord
marine fauna (Denmark). Ophelia 11:1-507.

RENSCH, B. 1943. Die Paldontologischen Evolutionsregeln in
zoologischer Betrachtung. Biologia Generalis 17:1-55.

RUSSELL HUNTER, W.[D.] 1949. The structure and behaviour

of HMiatella gallicana (Lamarck) and H. arctica (L.) with spe-
cial reference to the boring habit. Proc. Roy. Soc. Edinburgh
B63:271-289.

RUSSELL-HUNTER, W. D. 1982. Limpet. McGraw-Hill En-
cyclopedia of science and technology. 5th Edition. 7:708-
709.

RussELL HunTer, W. D. & S. C. Brown. 1964. Phylum
Mollusca. Pp. 129-152. Jn: R. I. Smith (ed.), Keys to the
marine invertebrates of the Woods Hole region. Marine
Biological Laboratory: Woods Hole, Massachusetts.

RUSSELL-HUNTER, W. D. & J. S. TASHIRO. 1973. Life-habits
of Cumingia tellinoides: an example of convergent adapta-
tion. Biol. Bull. 145:453.

SIMPSON, G. G. 1961. Principles of animal taxonomy. Colum-
bia University Press: New York. 247 pp.

STANLEY, S. M. 1970. Relation of shell form to life habits of
the Bivalvia (Mollusca). Mem. Geol. Soc. Amer. 125:1-296.

TRUEMAN, E. R. 1953. The structure of the ligament of the
Semelidae. Proc. Malacol. Soc. Lond. 30:30-36.

TRUEMAN, E. R. 1966. The cardinal ligament of the Telli-
nacea. Proc. Malacol. Soc. Lond. 37:111-117.

TRUEMAN, E. R. 1968. The burrowing activities of bivalves.
Symp. Zool. Soc. Lond. 22:167-186.

TRUEMAN, E. R., A. D. ANSELL, A. R. BRAND & P. DAvis.
1966. The dynamics of burrowing of some common littoral
bivalves. J. Exp. Biol. 44:469-492.

TUNNICLIFFE, V. & M. J. Risk. 1977. Relationships between
the bivalve Macoma balthica and bacteria in intertidal sedi-
ments: Minas Basin, Bay of Fundy. J. Mar. Res. 35:499-
507.

YONGE, C. M. 1949. On the structure and adaptations of the
Tellinacea, deposit-feeding Eulamellibranchia. Philos. Trans.
Roy. Soc. Lond., series B 234:29-76.

YONGE, C. M. 1957. Mantle fusion in the Lamellibranchia.
Pubbl. Staz. Zool. Napoli 29:151-171.

The Veliger 27(3):261-265 ( January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

Patterns of Sex Change of the Protandric Patellacean

Limpet Lotta gigantea (Mollusca: Gastropoda)

by

DAVID R. LINDBERG

Museum of Paleontology, University of California, Berkeley, California 94720

AND

WILLIAM G. WRIGHT

Scripps Institution of Oceanography, La Jolla, California 92093

Abstract.

Experiments were done to test the effects of density and age on the probability of sex

change in the protandrous limpet Lottia gigantea (Sowerby, 1834). Because of tag loss and mortality,
final numbers of individuals in each experiment were low. However, some trends are present in these
data that are distinctive. Young, territorially subordinate limpets, transplanted to large, isolated, empty
territories, had a low proportion of sex changers during the first year of the experiment (4/22), but a
significantly higher proportion during the second year (9/11). Limpets maintained at higher densities
had a low proportion of sex changers during both the first (1/7) and second (1/5, 1/7, 1/12) years
after transplantation, regardless of age. These data suggest that either low density promotes sex change
with a one year lag period, or that high density inhibits sex change that would otherwise occur when
the limpets are 2 to 3 years old. The presence of an inherent probability of sex change cannot be ruled

out.

INTRODUCTION

SEX-CHANGING MARINE invertebrates have received con-
siderable attention over the last few years (see review by
POLICANSKY, 1982). Most of the documented cases involve
protandry (male — female) and several scenarios and
models have been proposed to explain its selective advan-
tage or adaptive significance (GHISELIN, 1974; WARNER,
1975; CHARNOV & BULL, 1977).

Protandry has often been investigated in the Mollusca,
and occurs in a diverse group of taxa within the phylum
(POLICANSKY, 1982). Taxa with copulatory structures are
usually the subjects of these investigations because changes
in sex are readily detected by examining external struc-
tures (COE, 1944). However, the development of a tech-
nique allowing direct sampling of the gonadal contents of
suspected protandric species that lack external characters
(e.g., patellacean limpets) (WRIGHT & LINDBERG, 1979)
enabled us to monitor directly protandry in the limpet
Lottia gigantea (Sowerby, 1834) (WRIGHT & LINDBERG,
1982).

In this paper we report results of initial experiments to
determine the ecological and interactive factors influenc-
ing sex change in L. gigantea. Although our results are
not entirely conclusive, we present them because these
data suggest a complicated pattern of sex change involving
ecological factors, lag periods, and possibly genetic prob-
abilities of sex change within the population. It is our
intention to bring these data to the attention of other
workers so that possible antagonistic or synergistic effects
of these phenomena are not confused or overlooked in
other studies.

MATERIALS anp METHODS

Lottia gigantea is a large, territorial, intertidal limpet,
sometimes reaching lengths over 100 mm (STIMSON, 1970).
Larger individuals occupy either isolated territories (usu-
ally surrounded by sessile invertebrates such as barnacles
and mussels) (Figure 1) or contiguous territories (where
they occur at such high density that territorial boundaries
are impossible to discern) (Figure 2). Younger, smaller

Page 262

ihe Veliger, VolyZipaiows

Explanation of Figures 1 and 2

Figure 1. Low density experimental treatment on San Nicolas Island, California.

Figure 2. High density experimental treatment on San Nicolas Island, California.

individuals typically graze on the territories of larger in-
dividuals and respond to contact with the resident limpet
by escaping to the perimeter of the territory before the
resident can respond aggressively (WRIGHT, 1982). Most
limpets can be categorized behaviorally as either intruders
or residents; intruders are always evasive while residents
are usually aggressors (WRIGHT, 1982).

The growth of Lottia gigantea is relatively indetermi-
nate; although each habitat imposes a maximum size above
which no limpet can grow, that size ranges from 40 mm
to above 70 mm depending on characteristics of the habitat
(z.e., density of other grazing herbivores, intertidal height,
wave exposure, substratum, etc.). In addition, individual
growth varies inversely with size relative to the local max-
imum (Wright, unpublished data). Thus, a 40-mm limpet
in a local population where the maximum size is near 40
mm is growing slowly, if at all, and generally will be older
than a 40-mm limpet in a population where the maximum
size is nearer to 70 mm. We quickly realized that older,
slower growing limpets could be recognized by their heavily
eroded shells (Figure 4) while younger, fast growing lim-
pets could be recognized by the checkerboard pattern of

their shells (Figure 3). Using these criteria, we could
roughly judge the relative age of L. gigantea by external
appearance within a habitat.

Experimental manipulations of Lottia gigantea were done
on San Nicolas Island, Ventura County, California
(33°16'N, 119°30'W) between December 1980 and De-
cember 1982. In all treatments, the experimental limpets
were removed from the substratum while moving (to avoid
trauma) and sexed by sampling the gonad through the
rear body wall with a hypodermic syringe (WRIGHT &
LINDBERG, 1979). The dorsal surface of the shell was
marked with a plastic number embedded in waterproof
epoxy before the limpet was placed in either a low (Figure
1) or high density (Figure 2) setting.

The first experiment, begun in December 1980, tested
the hypothesis that high density lowers the probability of
sex change. The experiment was performed with 35 males,
all of which were observed to exhibit evasive behavior. Of
these 35, 26 were placed on isolated empty territories (low
density) where food supply was abundant and detrimental
interactions with other Lottia gigantea nil. Seven males
were placed in a high density setting of limpets with in-

D. R. Lindberg & W. G. Wright, 1985

Page 263

Explanation of Figures 3 and 4

Figure 3. Lottia gigantea. Young, checkerboard specimen; length = 55 mm.

Figure 4. Lottia gigantea. Old, eroded specimen; length = 60 mm.

discernable boundaries. In such settings, food would be
sparse and interactions frequent and potentially detrimen-
tal.

The second experiment, begun in December 1981, was
designed to test the effect of age on the probability of sex
change. We selected 35-mm to 45-mm ‘old’ and ‘young’
males by using the shell erosion criterion discussed above.
We placed all of these in a high density treatment identical
to the high density treatment in the first experiment.

At the end of each year (December) the gonadal con-
tents of the limpets were sampled. Limpets that had be-
come female were removed from the experimental settings
and dissected to verify sex change and to check for possible

9 males
: 5 Wright & Lindberg (7)
4 temales
5 males
2 7 males 5 males
high density ‘female 1 female
6 males 4 males

c 26 males 11 males
low density aan Sa

4 temales 9 females
22 males 2 males
old 7 males
: ? 1 female
high density 6 males
young 12 males
1 female
11 males
Dec Dec Dec Dec
1979 1980 1981 1982
Figure 5

Patterns of sex change in Lottia gigantea. Number of males mon-
itored during the experiment appears above the line, results be-
low the line. #@ = monitoring times, (7) = (1982).

simultaneous hermaphroditism. Males were replaced in
their experimental positions.

RESULTS

The results of the high and low density experiments are
shown in Figure 5 and Table 1. Also included in the
figure are data for Lottia gigantea sex change from WRIGHT
& LINDBERG (1982).

The proportion of males changing sex during the first
year was low in all treatments (0.08 to 0.15) and did not
appear to be affected by density or age (x’, P > 0.05).
During the second year, 9 out of 11 in the low density
treatment changed sex versus only 1 out of 5 in the high
density treatment. These were not significantly different
proportions (Fisher’s exact text, P = 0.071) perhaps due
to the low numbers in the high density treatment. In fact,
the only significant difference throughout all treatments
was between the limpets in the low density treatment at

Table 1

Percent and number of male Lottia gigantea changing sex
in various treatments. Lines connecting treatment per-
centages indicate significant differences at the 0.05 level
or greater (Fisher’s exact test). All other proportions not

significantly different (P = 0.05).

Percent changing sex and (n’s)

Treatment First year Second year
High density (HD) 14% (1/7) 20% (1/5)
HD Old 14% (1/7) —
HD Young 8% (1/12) —

Low density 15% (4/26) 82% (9/11)

Page 264

the end of two years, and any of treatments at the end of

one year.
No simultaneous hermaphrodites were found.

DISCUSSION

Formally, our data support nothing more than the state-
ment that “limpets in the second year of a sex change
experiment change sex more than during the first year.”
There are two interpretations of this conclusion. (1) The
limpets that were used in the density experiment (both
treatments) were all of similar age and sex change is age-
specific. (2) Limpets respond to changes in environmental
conditions (7.e., abundant food, no agonistic losses) by
changing sex, but there is a lag period greater than 12
months but less than 24 months between environmental
change and sex change. We favor the second interpreta-
tion for several reasons. First, based on a preliminary
aging technique, there does not seem to be any single age
for sex change (Wright, personal observation). Males can
be found that are probably 5 years or older, and females
can be found that are probably no more than 1% years
old. Secondly, the results of the high density, young versus
old experiment (Figure 5, Table 1) argue against the pres-
ence of an age-specific sex change phenomenon. Finally,
the proportion of sex changers during the second year in
low (9/11) versus high (1/5) density treatments, although
not statistically significant, is highly disproportional—a
fact that cannot stand alone given statistical convention,
but that can tip the scales of a close argument. Thus, we
favor the second hypothesis and the presence of environ-
mental sex determination in Lottia gigantea.

In addition to the evidence supporting environmental
sex determination in Lottia gigantea, there is a second in-
triguing pattern present in the data. This is the proclivity
of about 15% of the population to change sex annually
regardless of environmental setting or age (Table 1). This
pattern may represent a genetically programmed sex
change component that is virtually immune to environ-
mental factors. Thus, sex change in L. gigantea may be
regulated by two mechanisms: (1) environmental sex de-
termination and (2) genetically programmed sex change.
Another explanation for the persistent low proportion of
sex changers in our treatments is that the limpets that
changed had experienced an environmental release the
year before they were used in the experiment. A final
possibility is that the sex changers were simply responding
to variations within the two treatments. Although we can-
not rule out any of these possibilities, it is unlikely that
all of the treatments we set up in December of 1980 and
again a year later in December of 1981 all received similar
proportions of these predisposed changers and/or had
similar environmental variabilities within the study sites.

Neither environmental nor genetically programmed sex
determination was suggested by the results of our first
experiment (WRIGHT & LINDBERG, 1982; Figure 5
herein). We believe that the high proportion of sex chang-

The Veliger; Vola2iAiNiows

ers in our first experiment (4/9) resulted because we con-
founded limpets with different histories. Although we
carefully chose limpets that were about the same size, we
did not know the territorial status of the limpets, and
therefore, our experiment undoubtedly contained both in-
truders and residents. Thus, some of the males that changed
sex may have been in low density situations for as much
as a year prior to our using them in the experiment, and
our results therefore include both environmentally deter-
mined sex changers that were programmed to change sex
the year before, as well as limpets that were genetically
programmed to change sex that year. Because of this com-
plication, we do not feel that the earlier data set can be
combined or compared with the data set presented herein.

In most previously studied protandrous marine inver-
trates (see review by HOAGLAND [1978]) sex change is
predominately genetically regulated or environmentally
determined. In the echiuroid genus Bonellia both environ-
mental sex determination and genetic sex determination
appear to be important (GOULD-SOMERO, 1975; LEU-
TERT, 1975). In Bonellia the two different mechanisms of
sex change are thought to represent two different geno-
types in the population. The first contains “true” males
and females that are genetically determined and do not
change sex; the second contains a genotype in which sex
is environmentally determined.

Scenarios to explain protandry in patellacean limpets
have relied exclusively on genetic interpretations, includ-
ing rather elaborate hypotheses with two or more geno-
types in the population, representing true males and fe-
males and individuals changing sex at different ages
(MONTALENTI & Baccl, 1951). Recent analysis of static
sample data for Patella vulgata in England has identified
an age-specific property associated with sex change (BAL-
LANTINE, 1961; CHARNOV, 1982) and BRANCH (1974a)
has presented data for Patella oculus (Born, 1778) from
South Africa that strongly suggest an age-specific genetic
mechanism. However, for Lotta gigantea and many other
species of patellacean limpets age- and/or size-specific sex
change and its resulting sex ratios are less apparent in
static samples. Typically there are both small females and
large males present in these samples. Moreover, the switch
in the sex ratio from predominately males to predomi-
nately females is not sharp, but spread over several age
or size classes (BRANCH, 1974b; WRIGHT & LINDBERG,
1982).

The tendency for workers to propose multiple geno-
types for some protandrous species may result from an
observation bias. In studies of species in which sex change
can be externally observed (e.g., in the Calyptraeidae) sex
change is often found to be a response to environmental
change. However, there has been no such conclusion for
molluscan species in which gender can be determined only
once. Instead, genetic control alone is postulated to be
responsible for sex change. Workers on this latter group
of species have had to complicate their genetic hypotheses
in order to explain the apparently large variation in the

D. R. Lindberg & W. G. Wright, 1985

timing of sex change; such variation is inferred from the
wide distribution of sexes as a function of size. Thus, they
must further hypothesize the existence of one or more
additional genotypes that change sex at different ages and/
or a genotype that does not change sex at all. Missing
from these discussions is the possibility of environmental
sex determination, in spite of its utility in explaining high-
ly variable size of sex change (7.e., a highly variable or
complex environment). Based on the results presented here,
we can rule out to some extent the importance of the
different-genotype hypothesis because under no conditions
would it predict that such a high proportion of limpets as
9 out of 11 would change sex.

We have presented data suggesting that environment
(including the social interactions among conspecifics) can
control to some degree when sex change occurs in Lottia
gigantea. We believe that our experiments suggest envi-
ronmental control as an alternative hypothesis to multiple
genotypes in explaining the causes of sex change in other
patellacean limpets, especially when the limpet shows ter-
ritoriality and/or other indications of profound environ-
mental and/or social changes during its ontogeny (BRANCH,
1974b, 1975).

The ultimate cause of sex change in patellacean limpets
is hormonal (CHOQUET, 1969). We have attempted to
identify and elucidate proximate causes that can result in
the patterns of sex change seen in our experimental ma-
nipulations and in static population samples. Although
preliminary, we present them because they indicate that
mechanisms could be overlooked if experimental manip-
ulations are not followed for at least two years or if the
past histories of the manipulated animals are not known
or at least limited (7.e., presence of evasive behavior in
Lottia gigantea). Moreover, our data suggest that two
mechanisms (environmental sex determination and un-
derlying genetic determination) may be present. Such
multiple effects can produce results that are difficult to
interpret in static samples, short term experiments, or in
traditional paradigms, and may ultimately lead to an in-
correct interpretation of the mechanisms or an underes-
timation of the processes controlling sex change.

ACKNOWLEDGMENTS

We thank R. D. Field and A. L. Shanks for assistance in
the field, J. A. Estes, K. E. Hoagland, and an anonymous
reviewer for criticism of the manuscript, and the staff of
the U.S. Naval Pacific Missile Test Center (especially R.

Page 265

Dow) for access to San Nicolas Island. This study was
supported by the U.S. Fish and Wildlife Service.

LITERATURE CITED

BALLANTINE, W. J. 1961. The population dynamics of Patella
vulgata and other limpets. Doctoral Thesis, Queen Mary
College, London Univ. 236 pp.

BRANCH, G. M. 1974a. The ecology of Patella Linnaeus from
the Cape Peninsula, South Africa. 2. Reproductive cycles.
Trans. Roy. Soc. So. Africa 41:111-160.

BRANCH, G. M. 1974b. The ecology of Patella Linnaeus from
the Cape Peninsula, South Africa, 3. Growth-rates. Trans.
Roy. Soc. So. Africa 41:161-193.

BRANCH, G. M. 1975. Mechanisms reducing intraspecific
competition in Patella spp.: migration, differentiation and
territorial behaviour. J. Anim. Ecol. 44:575-600.

CuHaARNOV, E. L. 1982. The theory of sex allocation. Princeton
Univ. Press: Princeton, New Jersey. 355 pp.

CHarRnov, E. L. & J. BULL. 1977. When is sex environmen-
tally determined? Nature 266:828-830.

CHOQUET, M. 1969. Contribution a létude de cycle biologique
et de l’inversion de sexe chez Patella vulgata L. (Mollusque
Gastéropode Prosobranche). Thése Doct. Sci. Nat. Lille 185:
1-234.

Corer, W. R. 1944. Sexual differentiation in mollusks. II. Gas-
tropods, amphineurans, scaphopods, and cephalopods. Quart.
Rev. Biol. 19:85-97.

GHISELIN, M. T. 1974. The economy of nature and the evo-
lution of sex. Univ. of Calif. Press: Berkeley, Calif. 346 pp.

GOULD-SOMERO, M. 1975. Echiura. Pp. 277-312. In: A. C.
Giese & J. S. Pearse (eds.), Reproduction of marine inver-
tebrates, III. Academic Press: New York.

HOAGLAND, K. E. 1978. Protandry and the evolution of en-
vironmentally-mediated sex change: a study of the Mollus-
ca. Malacologia 17:365-391.

LEUTERT, R. 1975. Sex-determination in Bonellia. Pp. 84-90.
In: R. Reinboth (ed.), Intersexuality in the animal kingdom.
Springer-Verlag: New York.

MOoNTALENTI, G. & G. Bacci. 1951. Osservazioni e ipotesi
sulla determinazione del sesso negli ermafroditi. Sci. Genet.
4:5-12.

POLICANSKY, D. 1982. Sex change in plants and animals. Ann.
Rev. Ecol. Syst. 13:471-495.

STIMSON, J. 1970. Territorial behavior of the owl limpet, Lot-
tia gigantea. Ecology 51:113-118.

WARNER, R. R. 1975. The adaptive significance of sequential
hermaphroditism in animals. Amer. Natur. 109:61-82.
WRIGHT, W. G. 1982. Ritualized behavior in a territorial

limpet. J. Exp. Mar. Biol. Ecol. 60:245-251.

WRIGHT, W. G. & D. R. LINDBERG. 1979. A non-fatal meth-
od of sex determination for patellacean gastropods. J. Mar.
Biol. Assoc. U.K. 59:803.

WRIGHT, W. G. & D. R. LINDBERG. 1982. Direct observation
of sex change in the patellacean limpet Lottia gigantea. J.
Mar. Biol. Assoc. U.K. 62:737-738.

The Veliger 27(3):266-272 ( January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

Sediment Correlates to Density of Crepidula fornicata

Linnaeus in the Pataguanset River, Connecticut

by

STEPHEN H. LOOMIS anp WENDY VanNIEUWENHUYZE

Department of Zoology, Connecticut College, New London, Connecticut 06320

Abstract.

Relationships among the density of Crepidula fornicata and various characteristics of the

sediments with which it is associated in the Pataguanset River, Connecticut, were examined. The
population is located in an area transitional between a relatively deep channel and an, intertidal sand
flat. Over 90% of the stacks were situated so that most of the snails were in direct contact with a soft,
silty substrate. The density of snails ranged from 0 to 43 individuals/m? and the greater densities were
associated with sediments that had a high percent cover of solid substrate, relatively high silt and clay
content, small mean grain diameter, and high organic content. Multiple regression analysis indicates
that 67% of the variance in density can be attributed to changes in percent cover of solid substrate and
another 19% of the variance in density can be attributed to changes in the organic content. The rest of
the independent variables did not significantly correlate with variance in density. The significance of
these data in relation to the ecology of C. fornicata is discussed.

INTRODUCTION

THE RELATIONSHIP between benthic organisms and var-
ious characteristics of the substrates with which they are
associated has been of interest to ecologists for a long time
(BADER, 1954; THORSON, 1966; SANDERS, 1958, 1960;
DRISCOLL & BRANDON, 1973; DRISCOLL, 1967; RHOADS
& YOUNG, 1970; CRAIG & JONES, 1966). A basic gener-
alization that has emerged from studies on fauna-sediment
relationships is that epifaunal suspension feeders are usu-
ally associated with coarser-grained or firm bottoms while
deposit feeders are usually associated with finer-grained
or soft substrates (DRISCOLL & BRANDON, 1973; DRISCOLL,
1967; RHOADS & YOUNG, 1970; SANDERS, 1958, 1960;
CRaIG & JONES, 1966). One apparent exception to this
generalization is the association of the epifaunal suspen-
sion feeder, the slipper shell Crepidula fornicata Linnaeus,
1758, with soft muddy substrates (DRISCOLL, 1967;
DRISCOLL & BRANDON, 1973; BARNES et al., 1973).

It has been suggested that this apparent anomaly can
be explained by the fact that individuals of Crepidula for-
nicata are found in stacks, raising them far enough above
the soft bottom to prevent fouling of their feeding mech-
anisms by suspended or resuspended sediment (FRETTER
& GRAHAM, 1962; DRISCOLL, 1967). However, using scu-
ba, we have observed living populations of this organism
in which most of the stacks were lying on their sides bur-
ied at least one centimeter in the soft, silt substrate. Be-

cause they can live in direct contact with silt substrates,
there may be other explanations for this anomaly. This
paper examines changes in the density of a C. fornicata
population in the Pataguanset River, Black Point, Con-
necticut (Figure 1) along a gradient of sediment types
ranging from coarse sand and pebbles at the mouth of the
river to soft mud 230 m upstream, in an attempt to elu-
cidate effects of substrate type on the biology of these
animals.

MATERIALS anpD METHODS

Density of the animals was measured using scuba along
50-m transects by counting all of the animals in consec-
utive 1-m? quadrats. At the same time, the number of
snails in each stack and the objects to which the snail at
the bottom of each stack was attached were recorded. Bot-
tom water samples were collected using a LaMotte water
sampling bottle. The salinity of the water samples was
measured with an American Optical, temperature-com-
pensated refractometer and the temperature of the sam-
ples was measured using a mercury thermometer. Bottom
topography was mapped using a surveyor’s level and
leveling rod.

A total of 21 transects was examined for the presence
of Crepidula fornicata. Transect 1 was located on the east
side of the mouth of the Pataguanset River and consecu-
tive transects were 20 m apart. Each transect was situated

S. H. Loomis & W. VanNieuwenhuyze, 1985

Watt's Island

—>z
c-)

Griswold
Island i
6

) 60m

e

©

~ nt
“

°
w

Page 267

Black Point

Figure 1

Map of the study area showing the location of transects 13 through 18, the limits of the population of Crepidula
formicata (the stippled area), and the location of the sample stations (black dots).

perpendicularly to the shoreline. This examination showed
that there was a population of C. fornicata associated with
transects 14 through 17 (Figure 1). The rest of the tran-
sects were either void of C. fornicata or contained only one
or two stacks. The density of the snails was highest on
transect 16 and fell off rapidly either upstream or down-
stream (Table 1). The highest density for each transect
was always found approximately in the center of the pop-
ulation. The quadrat on each transect with the highest
density was chosen as a sediment sampling station (Figure
1). Two other stations with no snails were identified on
transects 13 and 18 by extrapolating the location of the
population to these transects. These stations, therefore,
represented areas that had densities ranging from 0 to 43
snails/m*. Four sediment samples (approximately 200 g
each) were collected at each station by scooping the top 2
cm of the sediment into a wide-mouth jar and immediately
capping it. The samples were washed in distilled water to
remove salt, centrifuged at 12,000 x g for 30 min, and
oven dried at 75°C. Two of the samples were separated

according to particle size using a series of U.S.A. Standard
Testing Sieves and each size class was weighed to the
nearest 0.1 g. The silt and clay fraction (particles less than
4.20 ¢ [0.055 mm]) for each sample was suspended in 50
mL of distilled water in a graduated cylinder and particles
were separated according to size classes by the pipetting

Table 1

Location of the sediment sampling stations and density
of Crepidula fornicata at each station.

Density
Transect Quadrat no. (snails /m?)
13 25 0)
14 33 17
15 42 36
16 38 43
17 17 27
18 19 0

Page 268 The Veliger, Vol. 27, No. 3

30

26 28

22 24
@

18 20
é

14
Ss
tc
5 38
8 _
a 2 =
E =
}) ©
e=-2 77)

MONTH
Figure 2

Temperature and salinity of water taken from the station on transect 15 from September 1981 to August 1982.

method of KRUMBEIN & PETTIJOHN (1938). The other
two samples were oven dried at 75°C, weighed to the
nearest 0.1 mg, combusted at 650°C for 6 h, cooled and
reweighed to obtain an estimate of the organic content of
the sediment. Percent cover of solid substrate was mea-
sured by collecting all of the hard material on the surface
of the sediments (including shells, rocks, bottles, and wood)
in replicate 0.25-m? quadrats at each station. The outline
of each piece of material was traced on graph paper, cut
out, and weighed to the nearest 0.1 mg on a Mettler Bal-
ance. The weights were compared to the weight of a 4-
cm?’ piece of graph paper to calculate the surface area
covered by each piece.

Observations of the movement of particles into the man-
tle cavity of Crepidula fornicata were made in the following
manner. Surface sediments collected from the study site
were suspended in seawater, poured into a large glass
fingerbowl, and allowed to settle on the bottom of the
fingerbowl until the water was clear (usually about 3 h).
Stacks of C. fornicata were placed on the sediments with
either their left or right side down and carefully pushed
into the sediments until the lower edge of the shells was
about 1 cm below the surface of the sediments, corre-
sponding to the field conditions. Observations were made
immediately and at one-hour intervals for 6 h with a dis-
secting microscope. Initial observations indicated that pos-
tural movements of the snails were important for the
movement of particles into the mantle cavity. We mea-
sured these postural movements in the following way.
Stacks containing only two C. fornicata individuals were
made by fragmenting larger stacks. The animals on the
bottom of the small stacks were dissected from their shells,
resulting in single individuals attached to empty C. for-
nicata shells. A small hole was drilled in the anterior-most

margin of each live snail’s shell. The live snails were con-
nected to the displacement transducer of a physiograph by
tying one end of a thread to the transducer and the other
end to the shell through the hole. The empty C. fornicata
shells to which the live animals were attached were an-
chored in a fingerbowl (which functioned as a counter-
weight) by four plastic coated copper wires with one end
embedded in wax. This apparatus was lowered into a
battery jar containing aerated seawater and movements of
the snail were recorded with the physiograph. Measure-
ments were made in the presence and absence of sedi-
ments.

RESULTS
Physical Characteristics at the Study Site

Water temperature (Figure 2) between September 1981
and August 1982 ranged from 22°C (in August) to —1°C
(in January). Bottom salinity within the population of C.
fornicata ranged from 19 to 29%o (Figure 2) and was never
different from surface salinity. These data were taken at
high tide and represent maximum values; however, the
salinity at low tide was never more than 3%o less than at
high tide.

Bottom profiles (Figure 3) revealed that the Crepidula
fornicata population was located in an area transitional
between a channel 2 m deep and an intertidal sand flat.
The tidal range at the study site is about 1 m and all
stacks were located below this range. Tidal flow velocity
at this site was high although rates were not measured.
The percent silt and clay of the sediments in the study
area ranged from 0.2% where there were no C. fornicata
to 19.6% where the density was intermediate. Mean grain
diameter ranged from 3.6 ¢ (0.08 mm) in areas of inter-

S. H. Loomis & W. VanNieuwenhuyze, 1985

Co)
Transect 15
1
£2
<=
a
o
a
oO
Transect 17
1
Et 2
i
~~
a
®
a
oO 10 20 30 40 50

Distance From Shore (m)

Page 269

(0)

Transect 16
1
2
(0)

Transect 18
1
2
oO 10 20 30 40 50

Distance From Shore (m)

Figure 3

Bottom profile of transects 15 through 18 showing transition between channel and sand flat. Depths were taken
from mean high tide. The vertical bars represent the limits of the Crepidula fornicata populations (there were no

C. fornicata found in transect 18).

mediate density of C. fornicata to 2.4 @ (0.185 mm) in
areas without C. fornicata. Sediment sorting (as measured
by the Trask Sorting Coefficient) became increasingly poor
with decreasing grain diameter (Figure 4). The organic
content of the sediments ranged from 0.44% to 1.79%.
Scattergrams of density of C. fornicata versus various char-
acteristics of the sediments are shown in Figure 5. Using
simple linear regression, there appears to be a positive
relationship between density and the percent cover of solid
substrate, ash weight, and mean grain diameter, but not
with percent silt or clay (Figure 5). Simple linear regres-
sion analysis, however, does not include information on
interrelationships between independent variables and, thus,
may not provide an accurate assessment of relationships
between the dependent variable and the combination of
all independent variables. Multiple regression analysis,
however, does include this information and shows that
67% of the variance in density can be attributed to changes

in the percent cover of solid material and that another
19% of the variance in density can be attributed to changes
in the percent ash weight of the sediment (Table 2). The
other independent variables do not significantly correlate
with variance in density.

Characteristics of the Population

With the exception of a few stacks that had washed up
alive on the beach, all of the specimens of Crepidula for-
nicata were located subtidally. The size of the stacks ranged
from 1 to 11 animals with an average stack size of 3.8
animals. The substrates to which the live snails at the
bottom of the stacks were attached, along with the per-
centage of total stacks attached to each kind of substrate,
are shown in Table 3. Almost half of the stacks were
attached to dead C. fornicata shells while another 34% of
the stacks were attached to dead Littorina littorea shells.

Page 270

3.0

2.5

2.0

1.5

HE
°

°
uw

Trask Sorting Coefficient

2 3 4

Mean Grain Diameter (@)

Figure 4

The relationship between mean grain diameter and the sorting
of the sediments from the study site.

The rest of the stacks were attached to the shells of various
dead mollusks, dead horseshoe crabs (Limulus), or glass
bottles. All of the C. fornicata stacks except those attached
to dead Limulus or bottles were lying on their right or left
side and that side was buried at least 1 cm deep in the
substratum with the other side exposed to water. The
density of C. fornicata ranged from 0 to 43 individuals/
m*. The percent cover of solid substrate (shells, wood, and
bottles), which may be a measurement of the amount of
space available for the recruitment of new individuals
(HOAGLAND, 1979), ranged from 0 where there were no
C. fornicata to 9.4 where the density of snails was highest.

Behavioral Observations

Initial observations of the movement of water currents
into and out of the mantle cavity of Crepidula fornicata
indicated that postural changes of the snails might be im-

portant in feeding when the animals are associated with.

soft substrates. As C. fornicata rests upon the shell below
it, an opening is produced at the anterior end where the

The Veliger; VolhZ7/- Now

Table 2

Stepwise multiple regression analysis of density of C7ve-

pidula fornicata vs. percent cover of solid substrate (COV),

organic content (OC), percent silt and clay (SC), mean

grain size (MGS), and depth (DEP). NS represents no
significant information added.

Variable We Change in 7? Significance
COV 0.669 0.669 P < 0.001
OC 0.863 0.194 P < 0.05
sc 0.870 0.007 NS
DEP 0.905 0.036 NS
MGS 0.924 0.019 NS

animal’s shell margin meets the lower shell. The snails
appeared to undergo a cycle of movements that involved
changing the width of this opening., These movements were
measured using a physiograph and the results from one
animal are presented in Figure 6. The cycle begins when
the snail rapidly closes the aperture. This movement re-
sults in the rapid expulsion of water from the mantle
cavity which resuspends sediments into the water adjacent
to the animal. The aperture remains closed for a short
period of time and then opens again. When the aperture
is opened, water rushes into the mantle cavity. The ap-
erture remains open while the snail filters the resuspended
sediments from the water. Small movements while the
aperture is open may facilitate the movement of water
into and out of the mantle cavity. The cycle begins again
with the rapid closure of the aperture. The postural move-
ments have the secondary effect of clearing a free space in
the sediment just below the anterior end of the animals so
that water can circulate freely whether the stacks are on
their right or left side. Similar results were obtained from
all snails tested whether associated with sediments or not.

DISCUSSION

Crepidula fornicata in the Pataguanset River is associated
with sediments that have a silt and clay content ranging

Table 3
Substrates to which Crepidula fornicata stacks were
attached.
Number of % of total
Substrate stacks stacks
Crepidula fornicata 52 44.8
Littorina littorea 39 33.6
Bottle 7 6.0
Mytilus edulis 6 52)
Mercenaria mercenaria 6 5.2)
Limulus polyphemus 5 4.3
Busycon canaliculatum 1 0.9

S. H. Loomis & W. VanNieuwenhuyze, 1985

Density (Individuals/m2)

() 73 4 6 8 10
% Cover Solid Substrate

Density (Individuals /m2 )

2.0 2.4 2.8 Siz 3.6 4.0
Mean Grain Diameter (0)

Page 271

oO 0.2 0.4 0.6 0.8 1.0
Organic Content (mg/mg dry wt)

0 5 10 15 20 25
% Silt and Clay

Figure 5

Scattergrams of the density of Crepidula fornicata vs. percent cover solid substrate (a), organic content of the
sediments (b), mean grain diameter of the sediments (c), and percent silt and clay in the sediments (d) (7 value
and significance factors are given for linear regression of each of the independent variables).

from 0.2 to 19.6%, a mean grain diameter ranging from
3.6 @ (0.08 mm) to 2.4 ¢ (0.185 mm), organic content
ranging from 0.44 to 1.79%, and cover of solid substrate
ranging from 0.5 to 10%. The only sediment character-
istics that were correlated with the density of C. fornicata
were percent cover of solid substrate and organic content.

The correlation between cover of solid substrate and
the density of Crepidula fornicata is not surprising consid-
ering that the larvae of the snails require a solid substrate
upon which to settle (HOAGLAND, 1979). A new popula-

tion would not become established in areas that had no
solid substrate, and the greater the cover of solid substrate,
the greater would be the chances for the establishment of
new stacks. DRISCOLL (1967) obtained similar results in
a study of attached epifauna-substrate relations in Buz-
zards Bay, Massachusetts. He found that the highest den-
sities of C. fornicata were associated with “‘shell-rich”’ sub-
strates, although he did not present quantitative data on
the amount of solid substrate present.

The correlation between the organic content of the sed-

The Veliger, Volh275 Wows

Page 272
S 0.5
O
ma OFF
Lu h
5023
0.2 | |
= )
zt Ol i N
0 5 Co & 2 6
MINUTES
Figure 6

Physiograph recording of postural movements of an individual
Crepidula fornicata.

iments and the density of Cvepidula fornicata is not as
easily explained. Most epifaunal suspension feeders are
associated with sediments that have a low silt and clay
content and a mean grain diameter in the medium sand
range (SANDERS, 1958; DRISCOLL, 1967). This study and
others (DRISCOLL, 1967; DRISCOLL & BRANDON, 1973;
BARNES et al., 1973) suggest that C. fornicata is anomalous
in that it is an epifaunal suspension feeder but it is asso-
ciated with finer grained sediments that have a high silt
and clay content, high organic content, and whose sorting
becomes increasingly poor with decreasing mean grain
diameter. One reason that epifaunal suspension feeders
are not associated with finer grained sediments may be
low food availability in the water above these sediments
(TURPAEVA, 1959; SANDERS, 1958; DRISCOLL, 1967). If
C. fornicata could utilize the organic matter in the sedi-
ments as a food source, it might be able to survive on
sediments that exclude other epifaunal suspension feeders.
It appears that C. fornicata does have such a mechanism.
Postural changes allow the snails to resuspend fine sedi-
ments and filter them from the water. This mechanism
would require that the organic content of the sediments
be high enough to satisfy the oxidative requirements of
the animal. Therefore, the higher the organic content of
the sediments, the more likely it is that C. fornicata could
survive and reproduce. Another explanation for the exclu-
sion of epifaunal suspension feeders from finer grained
sediments may be that their filtering mechanism is clogged
by very fine surface sediments that are resuspended by
low velocity tidal flow (RHOADS & YOUNG, 1970). The
efficiency of filter feeding of Crepidula does decrease under
turbid conditions (JOHNSON, 1971), but it is likely that a

higher organic content of the sediments could compensate
for this decreased efficiency.

ACKNOWLEDGMENTS

We would like to thank James T. Carlton, Paul Fell,
William Niering, Scott Warren, and anonymous review-
ers for reading the manuscript and making valuable com-
ments. We would also like to thank the Nature Conser-
vancy for allowing access to the Pataguanset River.

LITERATURE CITED

BADER, R.G. 1954. The role of organic matter in determining
the distribution of pelecypods in marine sediments. J. Mar.
Res. 13:32-47.

BARNES, R. S. K., J. COUGHLAN & N. J. HOLMEs. 1973. A
preliminary survey of the macroscopic bottom fauna of the
Solent, with particular reference to Crepidula fornicata and
Ostrea edulis. Proc. Malacol. Soc. Lond. 40(4):253-274.

Craic, G. Y. & N.S. JONEs. 1966. Marine benthos, substrate
and paleoecology. Palaeontology 9:30-38.

DRIscoLL, E. G. 1967. Attached epifauna-substrate relations.
Limnol. Oceanogr. 12:633-641.

DrRisco._, E. G. & D. E. BRANDON. 1973. Mollusc-sediment
relationships in northwestern Buzzards Bay, Massachusetts,
U.S.A. Malacologia 12(1):13-46.

FRETTER, V. & A. GRAHAM. 1962. British prosobranch mol-
luscs, their functional anatomy and ecology. Ray Soc.: Lon-
don. 755 pp.

HOoaGLANnD, K. E. 1979. The behavior of three sympatric species
of Crepidula from the Atlantic, with implications for evo-
lutionary ecology. Nautilus 94(4):143-149.

JOHNSON, J. K. 1971. Effect of turbidity on the rate of filtra-
tion and growth of the slipper limpet, Crepidula fornicata
Lamarck, 1799. Veliger 14(3):315-320.

KRUMBEIN, W. C. & F. S. PETTIJOHN. 1938. Manual of sed-
imentary petrology. Appleton-Century-Crofts, Inc.: New
York. 549 pp.

Ruoaps, D. C. & D. K. Younc. 1970. The influence of de-
posit-feeding organisms on sediment stability and commu-
nity trophic structure. J. Mar. Res. 28:150-177.

SANDERS, H. L. 1958. Benthic studies in Buzzards Bay. I.
Animal-sediment relationships. Limnol. Oceanogr. 3:245-
258.

SANDERS, H. L. 1960. Benthic studies in Buzzards Bay. III.
The structure of the soft-bottom community. Limnol.
Oceanogr. 5:138-153.

THORSON, O. 1966. Some factors influencing the recruitment
and establishment of marine benthic communities. Neth. J.
Mar. Res. 3:241-267.

Turpaeva, E. P. 1959. Food interrelationships of dominant
species in marine benthic biocoenoses. Pp. 137-148. Jn: B.
N. Nikitin (ed.), Marine biology. Trans. Inst. Oceanology
20:302 pp.

THE VELIGER

© CMS, Inc., 1985
The Veliger 27(3):273-281 (January 2, 1985)

Histopathological and Histochemical Effects of Larval
‘Trematodes in Goniobasis virginica
(Gastropoda: Pleuroceridae)

by

JANE E. HUFFMAN

Department of Zoology and Physiology, Parasitology Laboratory,
Rutgers The State University, Newark, New Jersey 07102

AND

BERNARD FRIED

Department of Biology, Lafayette College, Easton, Pennsylvania 18042

Abstract. ‘The histopathological and histochemical effects of parasitism in Gonzobasis virginica (Gme-
lin, 1791) (Gastropoda: Pleuroceridae) by the rediae of Sphaeridiotrema globulus and Philophthalmus
megalurus and the microphallid sporocysts of a ubiquita type and a lecithodendriid of a virgulate type
are reported. The larval stages caused extensive damage to the digestive gland and the muscle sur-
rounding the gland either by ingesting host tissue or through increased pressure due to their sheer
numbers. There was no detectable hemocyte response by the molluscan host to the presence of living
rediae and sporocysts. The occurrence of dead rediae of S$. globulus did elicit a hemocyte response.
Rediae of S. globulus were found also in kidney and gill tissue. Decreases in glycogen, lipid, acid
mucopolysaccharide, and keratin content of the digestive gland occurred in parasitized snails. Amyloid
content was unchanged in parasitized snails. Double infections involving S$. globulus and microphallid
sporocysts, and P. megalurus and microphallid sporocysts, also occurred in G. virginica. Metacercariae
of S. globulus are found free between the shell and visceral mass and do not elicit any discernable
pathologic response in the snail.

INTRODUCTION

VARIOUS HISTOPATHOLOGICAL and histochemical investi-
gations have been made on digenean larvae and their mol-
luscan hosts (JAMES, 1965; WRIGHT, 1966; READER,
1971a, b). Previous studies have dealt with a variety of
mollusks (HurRST, 1927; PRATT & BARTON, 1941; CHENG,
1963a, b; PORTER et al., 1967; MoorE & HALTON, 1973;
BECKER, 1980) but none have involved the pleurocerid
gastropod Goniobasis virginica (Gmelin, 1791).
Goniobasis virginica is the intermediate host for Sphae-
ridiotrema globulus in Lake Musconetcong, New Jersey
(HUFFMAN & FRIED, 1983). Adults of this fluke produce
ulcerative hemorrhagic enteritis in mute swans and have
accounted for 142 deaths of these birds at Lake Musco-
netcong between September 1977 and December 1981

(Rosco—E & HUFFMAN, 1982). During the survey of G.
virginica by HUFFMAN & FRIED (1983), four species of
larval trematodes were found in this snail.

In the present investigation, a comparative study has
been made on the pathological and histochemical effects
of the rediae of Sphaeridiotrema globulus and Philophthal-
mus megalurus, the sporocysts of a microphallid of a ubi-
quita type, and a lecithodendriid of a virgulate type (two
different types of microphallids) on the digestive gland,
muscle, kidney, and gill of Goniobasis virginica. Stained
sections of uninfected snail tissues were compared with
similarly stained sections of parasitized tissue.

The morphology and function of gastropod digestive
gland cells have been disputed. SUMNER (1965) described
four morphologically distinct types of cells. BARFURTH
(1880), READER (1971a), and MoorE & HALTON (1973)

Page 274

recognized only three, while PORTER et al. (1967) and
PorTER (1970) reported two distinct cell types in Oxytre-
ma siliqua and Flumenicola virens respectively. Examina-
tion of existing reports also revealed that the same cell
type is designated by an assortment of names.

The studies reported here were initiated to determine
(1) histologically the loci of different trematode infections
within the snail host; (2) if the pathological and histo-
chemical response varies depending upon the species of
larval trematode involved; and (3) the morphology of nor-
mal digestive gland of Goniobasis virginica as a base for
evaluating pathologic responses to larval trematode infec-
tions.

MATERIALS anpD METHODS

Specimens of Gonzobasis virginica ranging in length from
20 to 30 mm were collected from Lake Musconetcong,
New Jersey, and maintained in the laboratory in a 38-L
filtered aquarium containing lake water. Snails were
crushed within 3 days after collection and were examined
under a dissection microscope. Forty infected snails were
divided into four groups of ten, with each group repre-
senting one of the four species of larval trematodes. Two
groups of five snails, each doubly infected with Sphaeri-
diotrema globulus or Philophthalmus megalurus and a mi-
crophallid, were processed for study along with ten un-
infected snails. Parasitized and nonparasitized snails were
removed from their shells and fixed in 10% neutral buff-
ered formalin (NBF). For histopathological studies, tis-
sues were dehydrated in an alcohol series, embedded in
paraffin, sectioned at 6 um, and stained with hematoxylin
and eosin. For the detection of neutral lipids, tissues were
fixed in NBF, embedded at —20°C in an inert embedding
compound used for cryostat microtomy (O.C.T.; Ames
Co., Elkhart, Indiana), and sectioned at 8 um on a CTF
microtome-cryostat (International). For histochemical
studies, the tissues were dehydrated in an alcohol series,
embedded in paraffin, sectioned at 6 um, and the following
procedures (LUNA, 1968) were used: alcian blue, pH 2.5,
1.0, and 0.4 for acid mucopolysaccharides; periodic acid-
Schiff (PAS) reaction for complex carbohydrates, with
controls incubated in 0.5% malt diatase; Ayoub-Shklar’s
method for keratin (sulfur containing fibrous protein);
Bennhold’s method for amyloid (carbohydrate-containing
protein); Oil Red O in propylene glycol for neutral lipids;
Dahl’s alizarin red S method for calcium salts; Oil Red
O method for lipofuchsin; and Gomori’s one step tri-
chrome for connective tissue.

RESULTS
Morphology

The uninfected digestive gland of Goniobasis virginica
is orange or brown and occupies the upper whorls of the
shell. The digestive gland consists of numerous tubules
surrounded by loose connective tissue containing the vis-

The Veliger, Volh 27-sNoms

ceral hemocoelic space. The tubules are separated from
the hemocoel by a thin layer of loose connective tissue and
lined with glandular epithelium (Figure 1). This epithe-
lium is composed of two cell types, serous and mucous
cells. The serous cells are triangular. The cytoplasm at
the base of each cell is basophilic. The nucleus is round
and situated close to the base of the cell. The cytoplasm
toward the apex of the serous cells contains eosinophilic
granules. The mucous cells are columnar with flattened
nuclei which are crowded against the base of the cells.
There is less basophilia at the base of these cells than in
serous cells. The cytoplasm of mucous cells contains gly-
cogen, lipid, and amyloid. The serous cells contain kera-
tin, lipofuchsin, and calcium salts. The periphery of the
digestive gland consists of muscle (Figure 2). A mem-
brane, comprised of a single squamous epithelial layer
overlying a connective tissue layer, encloses the digestive
gland.

Gross Pathology Due to Sphaeridiotrema globulus

The digestive glands of snails infected with the rediae
of S. globulus are white. The rediae are readily visible as
robust white organisms, each with an orange longitudinal
streak. The streak is the pharynx and gut containing cel-
lular debris of host origin.

Histopathology Due to Sphaeridiotrema globulus

The rediae of S. globulus are located mainly in the pe-
riphery of the digestive gland (Figure 3) and cause exten-
sive damage to the muscle. Rediae are surrounded by clear
zones (Figure 4) devoid of cells. There is no detectable
hemocytic response on the part of the molluscan host to
the presence of living rediae. In snails with dead rediae
of S. globulus, there is a hemocytic response to the parasite
(Figure 5). Dead rediae differ from live rediae in that the
parasite’s muscular tissue and tegument undergo autolysis
with loss of cellular structure. The germinal cells within
rediae appear to be more resistant to autolysis and con-
sequently retain their normal appearance. In heavy, and
also in double infections involving microphallid sporo-
cysts, rediae are found abutting tubules in the digestive
gland, in the kidney, and in gill tissue (Figures 6, 7).
Digestive gland tubules in contact with rediae show re-
duced lumen size. The decrease in size is due to the pres-
sure exerted by large numbers of parasites. Rediae occur-
ring in the digestive gland disrupt the connective tissue
network.

The encysted metacercariae of Sphaeridiotrema globulus
also occur in Goniobasis virginica but are free between the
shell and visceral mass and do not elicit a discernable
pathologic response.

Histochemistry

The digestive gland of uninfected Goniobasis virginica
contains glycogen. Clumps of PAS-positive granules are

J. E. Huffman & B. Fried, 1985

Page 275

Explanation of Figures 1 to 3

Figure 1. Uninfected Goniobasis virginica digestive gland, illustrating tubule (T). H&E, 100~.

Figure 2. Uninfected Goniobasis virginica illustrating muscle (M) and tubule (T) of digestive gland. H&E, 100x.

Figure 3. Sphaeridiotrema globulus (Sg) rediae in the periphery of the digestive gland of Goniobasis virginica, also

illustrating tunica propria (TP). H&E, 100.

present throughout the cytoplasm of the mucous cells of
the digestive gland. With the infection of the digestive
gland with Sphaeridiotrema globulus, glycogen decreases
concurrent with the presence of PAS-positive material in
the rediae and cercariae of S. globulus.

Digestive gland cells in uninfected snails contain ker-
atin. Keratin is present in the rediae and cercariae of S.
globulus but host stores are not depleted. Dead S. globulus
rediae are surrounded by a thin layer of keratin.

Acid mucopolysaccharides (pH 2.5, 1.0, 0.4) were pres-

Page 276 he Veliger; Vole 27-eNioms

Explanation of Figures 4 to 7

Figure 4. Sphaeridiotrema globulus (Sg) in the periphery of the digestive gland illustrating clear zones (Cz) sur-
rounding the parasite. H&E, 100x.

Figure 5. Hemocyte response (H) to dead Sphaeridiotrema globulus (Sg). H&E, 450~x.
Figure 6. Sphaeridiotrema globulus (Sg) redia in gill tissue (G) of Goniobasis virginica. H&E, 100.
Figure 7. Sphaeridiotrema globulus (Sg) rediae in kidney (K) of Goniobasis virginica. H&E, 100.

_ J. E. Huffman & B. Fried, 1985

ent in uninfected snail digestive gland tissue and depletion
occurs in snails infected with S. globulus rediae. Amyloid
content is unchanged in parasitized snails.

In uninfected snails, neutral lipids occur in the mucous
cells of the digestive gland and scattered throughout in-
tertubular spaces. The neutral lipid content in tubules in
close proximity to S$. globulus rediae is diminished. Lipid
occurs in the body wall and gut of these rediae.

Gross Pathology Due to Philophthalmus megalurus

The digestive gland of snails infected with the redial
stages of P. megalurus is white and orange. The rediae are
visible to the naked eye. The rediae of P. megalurus are
more elongate and not as robust as those of Sphaeridiotre-
ma globulus.

Histopathology Due to Philophthalmus megalurus

The rediae of P. megalurus are located in the periphery
of the digestive gland and cause extensive disruption of
the myofibers in the periphery of the gland (Figure 8).
This parasite also invades the digestive gland (Figure 9),
causing decreased tubular lumen size due to the pressure
exerted by the parasite and disrupting the connective tis-
sue network. There is no host hemocytic response to the
living rediae. Rediae are surrounded by clear zones devoid
of cells.

Histochemistry

Glycogen and neutral lipid depletion occur in snails
infected with Philophthalmus megalurus. Glycogen is pres-
ent within the redial gut and body wall. Only tubules in
close proximity to parasites revealed a decrease in neutral
lipid content. Neutral lipid occurs in the body wall and
gut of the rediae.

Keratin occurs within the rediae and cercariae of P.
megalurus. The host digestive gland cells and muscles are
devoid of the substance. Rediae and cercariae accumulate
acid mucopolysaccharides concurrent with depletion from
host tissue. Amyloid content is unchanged in parasitized
snails.

Gross Pathology Due to Ubiquita Microphallid and
Virgulate Lecithodendriid

The daughter sporocysts of the microphallid and the
lecithodendriid are not visible to the naked eye; therefore,
gross pathology is not discernable. Once the snail tissue
is dissected, the small white rounded structures can be
seen with a dissecting microscope.

Histopathology Due to Ubiquita Microphallid and
Virgulate Lecithodendriid

The microphallid and lecithodendriid sporocysts are lo-
cated primarily in the visceral hemocoelic spaces of the
digestive gland (Figure 10). Digestive gland tubules in

A ee

Page 277

contact with sporocysts show a reduced lumen. There is
disruption of the connective tissue network. In heavily
infected snails, the digestive gland is reduced substantially
from its normal size. Sporocysts become intimately asso-
ciated with the digestive gland tissue and some sporocysts
abut the digestive tubules (Figure 12). The thin connective
sheath surrounding the tubule remains intact.

Histochemistry

Depletion of acid mucopolysaccharides (pH 2.5, 1.0,
0.4) occurs with both of the sporocyst infections. Abun-
dant amounts were found within the sporocysts. Glycogen
and neutral lipid depletion also occurred in both sporocyst
infections. Glycogen granules were associated with the
sporocyst body wall. Neutral lipids were demonstrated in
developing cercariae. Amyloid content was unchanged;
trace amounts do appear in the sporocysts.

In double infections (Figure 11), the observations were
the same as for single infections involving Sphaeridiotrema
globulus, Philophthalmus megalurus, and the microphallid.
The double infections occupy the periphery of the diges-
tive gland, kidney, and gills of infected snails.

DISCUSSION

Despite numerous studies of the gastropod digestive gland,
there is little agreement on the terminology and classifi-
cation of cell types. PAN (1958) described three cell types
in the digestive gland of Biomphalaria glabrata: goblet,
lime, and digestive. SUMNER (1965) described four types
of epithelial cells in Helix aspersa. PORTER et al. (1967)
recognized two types in Oxytrema siliqua: liver and cal-
cium cells. READER (1971a) recognized three types in Bi-
thynia tentaculata: absorptive, secretory, and thin cells.
Moore & HALTON (1973) described three cell types in
Lymnaea truncatula: digestive, mucous, and basophil cells.

Absorptive cells have previously been called liver, fer-
ment, digestive, secretory, or excretory cells. Secretory cells
have previously been referred to as lime, calcium, or ex-
cretory cells. Mucous and serous secreting cell types are
present in Goniobasis virginica. The epithelial cells of the
digestive gland in this gastropod have morphological char-
acteristics typical of mucous and serous secreting colum-
nar epithelium. These two morphologically distinct types
are further differentiated on the basis of their cytoplasmic
constituents identified by histochemical analysis.

Numerous studies have been made on the destruction
of molluscan digestive gland by larval trematodes (FAUST,
1920; AGERSBORG, 1924; Hurst, 1927; PRATT & BARTON,
1941; CHENG & JAMES, 1960; CHENG & SYNDER, 1962a,
b, 1963; PORTER et al., 1967; READER, 1971b; MEULE-
MAN, 1972; YOSHINO, 1976; TRIPP & TURNER, 1978). In
the present study, the rediae of Sphaeridiotrema globulus
and Philophthalmus megalurus, sporocysts of a microphal-
lid and a lecithodendriid trematode have some pathologi-
cal effects on the tissues of Goniobasis virginica.

Page 278 The Veligers; Vor 27 aNiows

Explanation of Figures 8 to 11

Figure 8. Philophthalmus megalurus (Pm) infection in Goniobasis virginica. H&E, 100x.
Figure 9. Philophthalmus megalurus (Pm) redia and sporocyst of a ubiquita microphallid (Um). H&E, 450x.

Figure 10. Sporocysts of a ubiquita microphallid (Um) in the digestive gland (tubule, T) of Goniobasis virginica.
H&E, 450~x.

Figure 11. Double infection of the digestive gland with Sphaeridiotrema globulus (Sg) and a ubiquita microphallid
(Um). H&E, 100~x.

J. E. Huffman & B. Fried, 1985

Page 279

Figure 12

Sporocyst of a ubiquita microphallid (UM) abutted to a tubule (T) in the digestive gland of Goniobasis virginica.

H&E, 1000x.

One difficulty in studies employing naturally infected
snails is that the sequence of pathology cannot be deter-
mined nor the long term consequences of infection on the
initial changes that occur at the beginning of infection.

The primary method of cell destruction and removal by
rediae of Sphaeridiotrema globulus in the digestive gland
appeared to be through ingestion. This was indicated by
the presence of host cellular debris in the redial gut. CHENG
(1963c) observed similar changes in Helisoma trivolvis in-
fected with Echinoparyphium sp. rediae. The rediae and
sporocysts reported in our study no doubt exerted me-
chanical pressure on the digestive gland tubules as evi-
denced by constricted tubular lumens. It is also possible
that the excretory products of the rediae and sporocysts
had a lytic effect on host tissue, as evidenced by the clear
zone around living trematodes. The clear zones were de-
void of cells and these zones may be edematous.

A hemocyte response to dead Sphaeridiotrema globulus
rediae was noted but no reaction occurred in response to
living larval trematodes. Many workers have noted little
or no cellular response to living trematode larvae in their
molluscan hosts (CHENG, 1963b; CHENG & BURTON, 1965;
JAMES, 1965; FENG, 1967; LOKER, 1978). Mechanisms by
which living parasites inhibit the ability of the mollusk to
recognize them as foreign is unknown (FONT, 1980). Dead
trematodes lose this capability and are attractive to the
hemocytes of the snail. MEULEMAN (1972) noted infiltra-

tion of hemocytes to foci of cellular necrosis as the result
of trematode activity.

Impairment of the digestive gland function may occur
as the result of Goniobasis virginica heavily infected with
larval trematodes. Whether or not this impairment has an
effect on survival of the snail is not known. CHENG &
SYNDER (1962a) reported that Helisoma trivolvis heavily
infected with Glypthelmins pennsylvaniensis can survive
the infection.

Many of the effects of intramolluscan parasites on the
host’s metabolism are known but difficult to generalize
(BECKER, 1980). The digestive gland of uninfected Gonzo-
basis virginica contains glycogen which appears as gran-
ular material scattered throughout the cytoplasm. In snails
infected with either sporocysts or rediae there was a de-
crease in the glycogen content of the digestive gland cells.
Concurrent with the depletion of host glycogen was an
increase in the glycogen content of developing parasites.
This depletion suggests the utilization of host glycogen by
these larval digeneans. The rediae probably derive most
of their glycogen by ingesting host cells. They may also
absorb nutrients through their body walls, but glycogen
is most likely too large to pass through the digenean body
wall (CHENG & SYNDER, 1963). Glycogen from the host
digestive gland is most likely hydrolyzed to monosaccha-
rides which pass out of gland cells into intertubular spaces.
A decrease in neutral lipid content was also evident in

Page 280

snails infected with either sporocysts or rediae. This also
suggests utilization of host lipid by these larval parasites.
The effects of glycogen and lipid depletion have been ex-
tensively studied in various molluscan hosts by CHENG
(1962, 1963a, b, c, 1965), CHENG & SYNDER (1962a, b,
1963), CHENG & BURTON (1966), JAMES (1965), PORTER
et al. (1967), NEGRUS (1968), READER (1971a), and
Rosson & WILLIAMS (1971).

Keratin, a fibrous protein, was found to be substantially
depleted only in snails infected with Philophthalmus me-
galurus. This protein was reported by Dixon (1965) in
the metacercarial cyst wall of Fasciola hepatica which en-
cysts on vegetation. Philophthalmus megalurus also encysts
on vegetation and the keratin uptake by this parasite may
be in preparation for the encystment process. The depo-
sition of a keratin sheath around the autolytic redia of
Sphaeridiotrema globulus appears to be an attempt by Go-
niobasis virginica to wall off the parasite.

ACKNOWLEDGMENTS

We thank Dr. D. E. Roscoe of the New Jersey Division
of Fish, Game and Wildlife for his helpful comments and
support.

LITERATURE CITED

AGERSBORG, H. P. K. 1924. Studies on the effect of parasitism
upon the tissue. I. With special reference to certain gastro-
pod molluscs. Quart. J. Microsc. Sci. 68:361-401.

BARFURTH, D. 1880. Die Leber der Gastropoden ein Hepa-
topancreas. Zool. Anz. 3:499-502.

BECKER, W. 1980. Metabolic interrelationships of parasitic
trematodes and molluscs, especially Schistosoma mansoni in
Biomphalaria glabrata. Z. Parasitenkd. 63:101-111.

CHENG, T. C. 1962. The effect of parasitism by the larvae
Echinoparyphium Dietz (Trematoda: Echinostomatidae) on
the structure and glycogen deposition in the hepatopancreas
of Helisoma trivolvis (Say). Amer. Zool. 2:328.

CHENG, T. C. 1963a. Biochemical requirements of larval tre-
matodes. Ann. N.Y. Acad. Sci. 113:289-321.

CHENG, T. C. 1963b. Histological and histochemical studies
on the effects of parasitism of Musculum partumeium (Say)
by the larvae of Gorgodera amplicava Looss. Proc. Helm.
Soc. Wash. 30:101-107.

CHENG, T. C. 1963c. The effects of Echinoparyphium larvae
on the structure of and glycogen deposition in the hepato-
pancreas of Helisoma trivolvis and glycogenesis in the par-
asite larvae. Malacologia 1:291-303.

CHENG, T. C. 1965. Histochemical observations on changes in
the lipid composition of the American oyster Crassostrea vir-
gimica (Gmelin), parasitized by the trematode Bucephalus
sp. J. Invertebr. Pathol. 7:398-407.

CHENG, T. C. & R. W. BuRTON. 1965. Relationships between
Bucephalus sp. and Crassostrea virginica: histopathology and
sites of infection. Chesapeake Sci. 6:3-16.

CHENG, T. C. & R. W. BuRTON. 1966. Relationships between
Bucephalus sp. and Crassostrea virginica: a histochemical study
of some carbohydrates and carbohydrate complexes occur-
ring in the host and parasite. Parasitol. 56:111-122.

CHENG, T. C. & H. A. James. 1960. The histopathology of

The Veliger, Vol: 27-3Nows

Crepidostomum sp. infection in the second intermediate host,
Sphaerium striatinum. Proc. Helm. Soc. Wash. 27:67-68.

CHENG, T. C. & R. W. SYNDER, JR. 1962a. Studies on host-
parasite relationships between larval trematodes and their
host. I. A review. II. The utilization of the host’s glycogen
by the intramolluscan larvae of Glypthelmins pennsylvaniens
Cheng, and associated phenomena. Trans. Amer. Microsc.
Soc. 81:209-228.

CHENG, T. C. & R. W. SYNDER, JR. 1962b. Studies on host-
parasite relationships between larval trematodes and their
hosts. III. Certain aspects of lipid metabolism in Helisoma
trivoluis (Say) infected with the larvae of Glypthelmins penn-
syluaniens Cheng and related phenomena. Trans. Amer.
Microsc. Soc. 81:327-331.

CHENG, T. C. & R. W. SYNDER, JR. 1963. Studies on host-
parasite relationships between larval trematodes and their
hosts. IV. A histochemical determination of glucose and its
role in the metabolism of molluscan and parasite. Trans.
Amer. Microsc. Soc. 82:343-346.

Dixon, K. E. 1965. The structure and histochemistry of the
cyst wall of the metacercariae of Fasciola hepatica L. Par-
asitol. 55:215-226.

Faust, E.C. 1920. Pathological changes in the gastropod liver
produced by fluke infection. Johns Hopkins Hosp. Bull. 31:
79-84.

FENG, S. Y. 1967. Responses of molluscs to foreign bodies with
special reference to the oyster. Fed. Proc. 26:1685-1692.

Font, W. F. 1980. Effects of hemolymph of the American
oyster, Crassostrea virginica, on marine cercariae. J. Inver-
tebr. Pathol. 36:41-47.

HuFFMAN, J. E. & B. FRIED. 1983. Trematodes from Gonzo-
basis virginica (Gastropoda: Pleuroceridae) in Lake Mus-
conetcong, New Jersey. J. Parasitol. 69:429.

Hurst, C. T. 1927. Structural and functional changes pro-
duced in the gastropod mollusc, Physa occidentalis, in the
case of parasitism by the larvae of Echinostoma revolutum.
Univ. Calif. Pub. Zool. 29:321-404.

JAMES, B. L. 1965. The effects of parasitism by larval Digenea
on the digestive gland of the intertidal prosobranch, Littorina
saxatilis (Olivi) subsp. tenebrosa (Montagu). Parasitol. 55:
93-115.

Loker, E. S. 1978. Normal development of Schistosomatium
douthitti in the snail Lymnaea catascopium. J. Parasitol. 64:
977-985.

Luna, L. G. 1968. Manual of histologic staining methods of
the Armed Forces Institute of Pathology. McGraw-Hill:
New York.

MEULEMAN, E. A. 1972. Host-parasite interrelationships be-
tween the freshwater pulmonate Biomphalaria pfeifferr and
the trematode Schistosoma mansoni. Neth. J. Zool. 22:355-
427.

Moore, M.N. & D. W. HALToN. 1973. Histochemical changes
in the digestive gland of Lymnaea truncatula infected with
Fasciola hepatica. Z. Parasitenkd. 43:1-16.

Necus, M. R. S. 1968. The nutrition of sporocysts of the
trematode Cercaria doricha Rothschild, 1935 in the mollus-
can host Turritella communis Risso. Parasitol. 58:355-366.

Pan, C. T. 1958. The general histology and topographic mi-
croanatomy of Australorbis glabratus. Bull. Mus. Comp. Zool.
119:237-299.

Porter, C. A. 1970. The effects of parasitism by the trema-
tode Plagioporus virens on the digestive gland of its snail host,
Flumenicola virens. Proc. Helm. Soc. Wash. 37:39-44.

Porter, C. A., I. PRATT & A. OWCZARZAK. 1967. Histopath-
ological and histochemical effects of the trematode Nano-

J. E. Huffman & B. Fried, 1985

phyetus salminocola (Chapin) on the hepatopancreas of its
snail host, Oxytrema siliqua (Gould). Trans. Amer. Microsc.
Soc. 86:232-239.

Pratt, I. & C. D. BarToN. 1941. The effects of four species
of larval trematodes upon the liver and ovotestis of the snail,
Stagnicola emarginata angulata (Sowerby). J. Parasitol. 27:
284-288.

READER, T. A. J. 1971a. Histochemical observations on car-
bohydrates, lipids and enzymes in digenean parasites and
host tissues of Bithynia tentaculata. Parasitol. 63:125-136.

READER, T. A. J. 1971b. The pathological effects of sporo-
cysts, rediae and metacercariae on the digestive gland of
Bithynia tentaculata (Mollusca: Gastropoda). Parasitol. 63:
483-489.

Rosson, F. M. & I. C. WILLIAMS. 1971. Relationships of some
species of Digenea with the marine prosobranch Littorina
littorea (L.). III. The effect of larval Digenea on the glyco-

Page 281

gen content of the digestive gland and foot of L. littorea. J.
Helminthol. 45:381-401.

Roscog, D. E. & J. E. HUFFMAN. 1982. Trematode (Sphae-
ridiotrema globulus) induced ulcerative hemorrhagic enteritis
in wild mute swans (Cygnus olor). Av. Dis. 26:214-224.

SUMNER, A. T. 1965. The cytology and histochemistry of the
digestive gland of Helix aspersa. Quart. J. Microsc. Sci. 106:
173-192.

Tripp, M. R. & R. M. TuRNER. 1978. Effects of the trematode
Proctoeces maculatus on the mussel Mytilus edulis. Comp.
Pathobiol. 4:73-84.

WRIGHT, C. A. 1966. The pathogenesis of helminths in the
Mollusca. Helminthol. Abst. 35:207-224.

YOSHINO, T. P. 1976. Histopathological effects of larval Di-
genea on the digestive epithelia of the marine prosobranch
Cerithidea californica: fine structural changes in the digestive
gland. J. Invertebr. Pathol. 28:209-216.

The Veliger 27(3):282-290 ( January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

Architectonica (Architectonica) karstent (Rutsch, 1934):

A Neogene and Recent Offshore Contemporary of

A. (Architectonica)

nobilis Réding, 1798

(Gastropoda: Mesogastropoda)

by

THOMAS J. DEVRIES

Institute of Polar Studies, The Ohio State University, Columbus, Ohio 43210

Abstract.

The subdued spiral and axial sculpture of the Miocene-early Pliocene mesogastropod

Architectonica (Architectonica) nobilis karstent Rutsch, 1934, has been used to distinguish it from the
more granulose A. (Architectonica) nobilis nobilis Roding, 1798, a long-ranging and widespread species
of the Caribbean and western tropical American shelf. Especially noteworthy in the former taxon is
the absence ventrally of a second, noded spiral cord and a second, wide spiral groove. Discovery of
Plio-Pleistocene specimens in northwestern Peru and Recent specimens from western tropical America,
all referable to A. nobilis karsteni, suggests that this form has maintained its phenotypic, and presumably
genotypic, integrity for as long as A. nobilis nobilis. A re-analysis of the shell morphology of A. nobilis
karsteni and a fresh consideration of its habitat suggest that the subspecies should be accorded specific
rank, namely, Architectonica (Architectonica) karstent (Rutsch, 1934).

INTRODUCTION

Architectonica (Architectonica) nobilis nobilis Réding, 1798,
is a low-spiral, solidly built mesogastropod characterized
by its granulose texture and strong spiral sculpture. This
species is a common constituent of Neogene and Recent
shelf faunas of the Caribbean and eastern tropical Pacific
Ocean (WOODRING, 1959; KEEN, 1971; ABBOTT, 1974).
Architectonica nobilis karstent Rutsch, 1934, is smoother
and less sculptured than the type form. It is also less
common, heretofore reported only from early Miocene to
early Pliocene sedimentary rocks of the southern Carib-
bean, Mexico, and Chile (e.g., BOSE, 1906; JUNG, 1965;
FRASSINETTI & COVACEVICH, 1981; see Figure 1). This
paper reports the first discovery of A. nobilis karsteni from
Plio-Pleistocene sediments and in modern shelf environ-
ments of western tropical America.

In 1981 and 1982 the author found several partial molds
of the “karsteni” form in gravelly-shelly sandstones near
the base of the Mancora Tablazo sequence in northwest-
ern Peru and in overlying siltstones of the same sequence

(Figure 1). These deposits were first described in some
detail by BosworTH (1922), and lately have been re-ex-
amined by DEVRIES (1982, and in preparation), the latter
author attributing the coarse and fine sediments, respec-
tively, to semi-protected inlet and deep lagoonal environ-

ments.

Numerous specimens of Architectonica nobilis karsteni
were recently recognized by the author among the collec-
tions of A. nobilis nobilis housed at the Los Angeles County
Museum of Natural History (LACM). This material was
collected live from midshelf depths between Baja Califor-
nia and Ecuador by the R/V Anton Bruun and other ves-
sels (Figure 1). A consideration of the taxonomy of these
specimens of A. nobilis karsteni is presented below, fol-
lowed by a discussion of the ecological data available for
fossil and modern occurrences. It will be argued that the
longevity of the “‘karsteni” form, its morphological and
ecological integrity, and possible European ancestry, to-
gether suggest the propriety of full specific rank for this
taxon, herein identified as Architectonica (Architectonica)

karsteni (Rutsch, 1934).

T. J. DeVries, 1985

Allen ress inc., Lawrence, KS 66044 USA

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Page 283

Neogene and Recent distribution of Architectonica (Architectonica) karstent (Rutsch). Each fossil locality is desig-

nated by the author of the record.

Page 284

TAXONOMY
Class Gastropoda
Subclass Prosobranchia
Order Mesogastropoda
Superfamily Architectonicacea
Family Architectonicidae Gray, 1850
Subfamily Architectonicinae Gray, 1850

Diagnosis: “Mainly heavy and solid species, 30-70 mm
max. diam., a few as small as 7.5 mm. Single peripheral
keel. Sculpture of strong cords and grooves, granose, tes-
sellated or almost smooth. Umbilicus wide and perspective
to narrow. Operculum chitinous, thin and flat” (GARRARD,
1977:510).

Genus Architectonica Réding, 1798
Subgenus Architectonica Réding, 1798

Type species: By subsequent designation (GRay, 1847:
151), Trochus perspectivus Linné, 1758.

Diagnosis: “Large to very large, medium to low conical;
medium to wide perspective umbilicus; strong peripheral
keel separated by a deep groove from both a dorsal and
basal cingulum; usually both axially and spirally grooved
and beaded, especially in early whorls; flat horny oper-
culum ...” (GARRARD, 1977:510).

Architectonica (Architectonica) karstent
(Rutsch, 1934)

Figures 2-12, 15, 16, 18, 20

Architectonica nobilis karstent RUTSCH, 1934:44, pl. 1, figs.
8-10.

Architectonica sexlinearis haughti MARKS, 1951:93, pl. 2, figs.
2, 6:

Architectonica (Architectonica) nobilis karstent Rutsch, 1934.
WOoDRING, 1959:167-168, pl. 30, figs. 1-3; JUNG, 1965:
488-489, pl. 64, figs. 8-10; JUNG, 1971:177, pl. 6, figs.
5, 6; FRASSINETTI & COVACEVICH, 1981:149-152, figs.
2a-2c.

Architectonica (Architectonica) nobilis subsp. WOODRING, 1973:
473, pl. 71, figs. 4, 5, 10, 11.

Solarium gatunense Toula, 1908. TRECHMANN, 1935:549, pl.
21, figs. 21, 22.

[non] Solarium gatunense TOULA, 1908:692-693, pl. 25, fig.
3 (=Architectonica nobilis Réding, 1798).

Solarium villarelloi BOSE, 1906 (in part):30-31, pl. 3, figs. 6,
te

Original description: Shell rather low-spired; base
strongly convex; umbilicus narrow. Base ornamented
completely differently than Architectonica nobilis: on the
keel, which surrounds the umbilicus, a deep wide furrow
follows outward and after that a wide zone with strong
radial folds. The two (up to three) granular spiral cords
that characterize A. nobilis are missing. Before the periph-

The Veliger; Voli 27-eNiorns

eral keel lies a partly granular spiral cord. The strong
spiral thread that lies between both of these cords of the
type specimen of A. nobilis is also missing . . . (free trans-
lation from original German description of RUTSCH, 1934).

Type locality: Punta Gavilan, northern Venezuela
(“Cantaure” Formation, Miocene; RUTSCH, 1934).

Location of type: Museum of Basel, Holotype 142/1769,
Museum No. 13.

Additional material: LACM 66-198. Four specimens
from R/V Anton Bruun cruise 18B, Station 778, 93 m,
W of Cabo Pasado, Ecuador (00°21'S, 80°41’W) collected
live. LACM collections contain other specimens of A. kar-
stent whose distributions are illustrated in Figures 1 and
DDk

OSU 36792. External mold of umbilical region and
portions of base. Detail is well-preserved in calcareous
gravelly sand. Collected by T. DeVries in 1981 from near
base of Mancora Tablazo section at Cabo Blanco, north-
west Peru.

Supplementary description: LACM 66-198a, b, c, d.
Small to moderate size (see Table 1), only moderately
thick, conical; umbilical width about % total diameter.
Protoconch not visible; teloconch with 7 whorls. Dorsal
sculpture one narrow, flattened, peripheral cord and four
wider cords, all granulose in early whorls, becoming
smooth or nearly smooth on body whorl; cords bear mi-
nute spiral striae and on the two abaxial dorsal cords, a
single weak spiral groove; grooves between dorsal cords
narrow, usually 4 to % as wide as adjoining cords. Ventral
sculpture consists of umbilical cord with numerous blunt
rectangular nodes; adjoined peripherally by wide, deep,
flat-bottomed groove. A sharply rounded spiral cord and
spiral thread lie adjacent to peripheral dorsal cord. Inter-
vening ventral area convex, crossed by radially splayed
wrinkles that gradually fade peripherally; wrinkles inter-
sected by 6 weakly developed spiral grooves and numerous
minute spiral striae. Weak parietal groove emerges on
columellar lip % the distance abapically from the edge of
succeeding whorl to the siphonal canal; a second weaker
groove is present anteriorly. Color uniformly pale brown
with radially directed bands of rectangular brown spots
on dorsal cords and discontinuous thin spiral bands of
brown on ventral side. Thin brown periostracum. Flat,
chitinous operculum.

OSU 36792. Moderate size (27 mm diameter); umbil-
ical cord with large rectangular nodes; bound peripherally
by a single wide, deep, flat-bottomed spiral groove. Ra-
dially splayed, well-defined wrinkles, fading peripherally;
single spiral cord against peripheral cord without inter-
vening spiral thread. Ventral area with 4, possibly 6, weak
spiral grooves passing between wrinkles.

Stratigraphic and geographic distribution: Northern
Venezuela, middle Miocene (RUTSCH, 1934; JUNG, 1965);
Carriacou (eastern Caribbean), late early-middle Mio-

T. J. DeVries, 1985

cene (TRECHMANN, 1935; JUNG, 1971); Panama, early
Miocene-early Pliocene (WOODRING, 1959, 1973); north-
ern Colombia, Miocene (J. W. Durham, personal com-
munication, 1984); Ecuador, middle Miocene (MaRKS,
1951), upper Miocene (Olsson, unpublished USNM ma-
terial, USGS Locality 23491); central Chile, early-middle
Miocene (FRASSINETTI & COVACEVICH, 1981); southeast-
ern Mexico, (?) early Pliocene (Bose, 1906; J. W. Dur-
ham, personal communication, 1984); northwestern Peru,
late Pliocene-early Pleistocene; Gulf of California to Ec-
uador, Recent (Figure 1, Table 2).

DISCUSSION

Although similar, Architectonica karsteni and A. nobilis
may be distinguished by several important morphologic
features, the most obvious being the absence ventrally of
both a second strongly noded spiral cord and a second
deep spiral groove on A. karsteni (see FRASSINETTI &
COVACEVICH, 1981). Other spiral grooves do appear on
the ventral face of A. karsteni, but these in no way resem-
ble the deep grooves of either species (see Figures 5, 13).
The latter are wide and squarely cut with a flat bottom.
The former are usually narrow, shallow, and V-shaped.
Significant gradations between these two groove forms are
rarely seen in the Recent material from LACM collections
and apparently never found in fossil specimens.

Most specimens of Recent Architectonica karsteni are
thinner-shelled, lower-spired, more convexly rounded
dorsally and ventrally, less granulose, and more uniformly
colored in drab brown than A. nobilis. Dorsally, spiral
grooves are narrower in A. karsteni; in A. nobilis, any of

Page 285

the dorsal grooves may be nearly half as wide as the ad-
jacent cords.

The spiral thread situated between the dorsal periph-
eral cord and the ventral cord near the periphery is pres-
ent to some degree in all Recent specimens of Architecton-
ica karstent, as are all four dorsal grooves. In these two
respects they resemble A. nobilis more than fossil A. kar-
stern, which usually lack the spiral thread and one or two
of the dorsal grooves.

The columellar lip of all Avchitectonica karsteni is quite
different from that of A. nobilis. The latter has a well-
developed groove only one-fourth to one-fifth the colu-
mellar lip length below the superseding whorl, rather than
one-third as in A. karsteni (Figures 16, 18-21). Ante-
riorly, the columellar lip of A. nobilis bears several tiny
pleats and grooves that are not present in A. karstent.

Specimens of Architectonica karstent from Panama
(WooDRING, 1959) and Ecuador (MARKS, 1951) were ex-
amined and compared with the newly discovered speci-
mens (Table 1). Dorsally, fossils from both localities were
somewhat less granulose and lacked one of four dorsal
grooves. Ventrally, the Panama specimens (USNM
562636) lacked the incipient spiral grooves present across
the entire base of the Recent specimens, but in the Ec-
uadorian specimens these nascent grooves (four in num-
ber) were readily visible. Undescribed upper Miocene A.
karsteni from Ecuador collected by Olsson and housed at
the U.S. National Museum (USGS Locality 23491) even
display a third, thin spiral thread near the periphery as
is seen on Recent specimens.

A close examination of the figure of Solarium gatunense
TOULA (1908) reveals two deep grooves encircling the um-

Explanation of Figures 2 to 14

Figures 2 to 12. Architectonica (Architectonica) karsteni (Rutsch, 1934).

Figure 2. LACM 66-198d. Recent, 93 m, off Cabo Pasado, Ecuador. Dorsal view. (1.67).
Figure 3. LACM 66-198b. Recent, 93 m, off Cabo Pasado, Ecuador. Dorsal view. (1.67).
Figure 4. LACM 66-198c. Recent, 93 m, off Cabo Pasado, Ecuador. Dorsal view. (<1.67).

Figure 5. LACM 66-198d. Ventral view. (1.67).
Figure 6. LACM 66-198b. Ventral view. (1.67).
Figure 7. LACM 66-198c. Ventral view. (1.67).
Figure 8. LACM 66-198d. Apertural view. (1.67).
Figure 9. LACM 66-198b. Apertural view. (x1.67).

Figure 10. LACM 66-198c. Apertural view. (<1.67).

Figure 11. OSU 36792. Late Pliocene-early Pleistocene, base of Mancora Tablazo sequence, Cabo Blanco, Peru.
Latex cast of partially preserved ventral surface and umbilicus. (1.4).

Figure 12. OSU 36792. Original sandstone mold from which latex cast (Figure 11) was made. (x1.4).
Figures 13 and 14. Architectonica (Architectonica) nobilis Réding, 1798.

Figure 13. LACM AHF-93839. Recent, Costa Rica. Ventral view showing two deep spiral grooves encircling

umbilicus. (x1.81).

Figure 14. LACM AHF-93839. Dorsal view showing wide dorsal spiral grooves. (<1.81).

Page 286 the Veligers Vola27-ows

T. J. DeVries, 1985 Page 287

Explanation of Figures 15 to 21

Figures 15, 16, 18, and 20. Architectonica (Architectonica) karsteni (Rutsch, 1934).

Figure 15. PRI 20444 (=A. sexlinearis haughti Marks, 1951). Middle Miocene, Daule Formation, Ecuador. Dorsal
view. Note presence of only three dorsal grooves on younger whorls. (1.46).

Figure 16. LACM 66-198a. Recent, 93 m, off Cabo Pasado, Ecuador. Lateral view of columella showing position
of principal adapical groove and weaker grooves abapically on the columellar lip. (1.45).

Figure 18. LACM 66-198a. Oblique apertural view of columella. (1.45).

Figure 20. USNM 562636. Miocene, Panama. Oblique apertural view of columella showing position of adapical
groove and absence of pleating on columellar lip. (1.75).

Figures 17, 19, and 21. Architectonica (Architectonica) nobilis Réding, 1798.

Figure 17. OSU 36794. Late Pleistocene, Lobitos Tablazo, northwestern Peru. Ventral view showing two strong
grooves bordering the umbilicus. (1.75).

Figure 19. OSU 36793. Recent, northwestern Peru. Apertural view showing pleated columellar lip.

Figure 21. LACM AHF-93839. Recent, Costa Rica. Apertural view showing position of columellar adapical
groove and pleated columellar lip. (1.81).

Page 288

O07 e e 1 |
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* dead specimen

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a |
190 | T T T T
4°s

T T
o° 4° 8° l2°

The Veliger; Vols 275Noxs

~<- (Outer Baja California)

*

|
Gulf|lof California

|
|
|

16° 20° 24° 28°N

Latitude

Figure 22

Latitudinal and bathymetric distribution of Recent Architectonica (Architectonica) karsteni (Rutsch). Data from
collections of LACM; material collected by R/V Anton Bruun and other vessels.

bilicus. Thus, Toula’s specimen is properly referred to
Architectonica nobilis. TRECHMANN (1935) was correct in
not assigning his Caribbean specimen to A. nobilis; when
referring it to S$. gatunense, he probably was unaware of
RUTSCH’s (1934) year-old description of A. karsteni.

As noted by RuTscH (1934), Architectonica karstent
bears a strong resemblance to European Miocene species
of the same subgenus, particularly A. grateloupi (d’Orbig-
ny, 1852) (COSSMANN, 1915:164, pl. 6, figs. 40, 41, 42),
A. carocollatum (Lamarck, 1822), and varieties of the lat-
ter (Sacco, 1892:40-41, pl. 1, fig. 35; STRAusz, 1966:
115-116, pl. 52, figs. 5, 7-10). Architectonica grateloupi is
less granulose than Recent A. karsteni but no less gran-
ulose than many fossil A. karsteni. Four dorsal cords are
present on all whorls, as in Recent A. karsteni. The um-
bilicus is somewhat wider than in any A. karsteni. Ar-
chitectonica grateloupi typically has not one, but two ven-
tral spiral threads adjacent to the dorsal peripheral cord.

Architectonica carocollatum and A. carocollatum var. pa-
lutinum (STRAUSZ, 1966) are also less granulose than Re-
cent A. karstent. Dorsal grooves are variably developed.
On the typical form of A. carocollatum only two of four
grooves are carried forward to the penultimate and ulti-
mate whorls. On the “‘palutinum” form, never more than
two dorsal grooves are present on any whorl.

Considering the specificity of the characters pertaining
to Architectonica karsteni in Recent populations and the
rarity of gradations in character with A. nobilis, the per-
sistence of these characters through 20 million years, the
widespread geographic range of the “‘karsteni” form, past
and present, and the ecological arguments presented be-
low, it is concluded that A. (A.) nobilis karstent should be
elevated to specific status.

Despite some morphological overlap between Recent
Architectonica karsteni and A. nobilis, there is no reason
that A. karsteni must be considered a New World Neo-

eae eWViniess 1.985

Page 289

Table 1

Dimensions of selected Architectonica specimens, includ-
ing specimens of A. karsteni illustrated in this paper.

Diam-
eter

Specimen (mm)

Architectonica karstem

LACM 66-198a 33.5
LACM 66-198b 28.5
LACM 66-198c 28.0
LACM 66-198d 27.8
OSU 36792 27

USNM 562636 37

SGOP 13122 24.8
PRI 20443 19.9
PRI 20444 3552,

Architectonica nobilis

AHF 939-39 38.2
OSU 36793 37.0
OSU 36794 31.0

Locality

Umbil-
thee Most Recent specimens of Architectonica karsteni in the
(mm) UW/D LACM collection were recovered from depths in excess of
50 m, whereas A. nobilis was usually found at lesser depths
(Figure 22). Only along the narrow continental shelf be-
12.6 0.38 tween 16 and 24°N was A. nobilis common at depths great-
ea Ds er than 50 m.
10.0 0.36 : : ; : .

97 0.35 Most fossil specimens of Architectonica karsteni were
11.2 0.40 probably deposited in an offshore setting (Table 2). Fossil
14 0.4 A. nobilis occur in the same strata as A. karsteni, as well

93 0.37 as in adjacent strata. There is no evidence that these oc-

OO N38 currences in other strata are from solely nearshore sedi-
133 0.38 ments. Thus, the apparent modern segregation of the two

species by water depth cannot be demonstrated for the
fossil record. Nonetheless, there is little basis for believing
Uae hed that A. karstent was ever a regular inhabitant of very
eae) hee) shallow water.
Ie G22 The 50-m break in the Recent distribution of the two
Table 2
Sedimentological information pertaining to Neogene and Recent occurrences of Architectonica (Architectonica) karstent
(Rutsch).
Sedimentology Age Author
Glauconite, limonitic sandy lime- Miocene Rutscu, 1934

Punta Gavilan, n.
Venezuela

Paraguana Peninsula,
n. Venezuela

Carriacou, Grenadine
Islands

Carriacou, Grenadine
Islands

Panama
Panama

Daule Basin,
Ecuador

Punta Perro, c. Chile

Tuxtepec, Mexico
Cabo Blanco, Peru

Ecuador to Gulf of
California; Baja
California Sur

Height
(mm) H/D
21.4 0.64
16.8 0.59
15.6 0.56
16.0 0.58
? ee
19 0.5
14.1 0.57
1255} 0.63
23.7 0.67
24.1 0.63
23.2 0.63
16.4 0.53

Formation

“Cantaure” Fm.

“Cantaure” Fm.

Grand Bay Fm.

Kendace Fm.
La Boca Fm.
Chagras Fm.
Daule Fm.

La Navidad
Fm.

Mancora Ta-
blazo beds

gene descendant of A. nobilis, given the ubiquity of forms
very similar to A. karsteni throughout the Miocene of
Europe.

ECOLOGICAL CONSIDERATIONS

stone

60% clay; thin-bedded sandstone;
thin-bedded limestone; 30 m
above bedrock

Ashy shale, fine agglomerates; her-
matypic and ahermatypic corals

Calcareous marls
Silty or tuffaceous mudstone; minor

conglomerate; coralline limestone
Massive fine sandstone and silt-

stone; overlies barnacle coquina
Blue siltstone
Coarse quartz sandstone
Poorly consolidated sands

Calcareous, gravelly sandstone

Gravel; mud; fine sand; shells

middle Miocene

middle Miocene

late early Miocene
early Miocene

late Miocene-early
Pliocene

middle Miocene

early—middle Mio-
cene

Pliocene

late Pliocene-early
Pleistocene

Recent

JUNG, 1965

TRECHMANN,
1935; JUNG,
1971

JUNG, 1971
WOODRING, 1973
WOODRING, 1959

Marks, 1951

FRASSINETTI &
COVACEVICH,
1981

BoseE, 1906
This paper

This paper

Page 290

The Veliger, Vol 2Z2i/-aNiows

Architectonica species in the eastern tropical Pacific Ocean
is approximately coincident with the lower boundary of
the permanent oceanic thermocline (e.g., PATZERT, 1978).
Water temperatures immediately beneath the thermocline
fluctuate seasonally but are generally several Centigrade
degrees cooler than surface waters. Given that the iso-
therms at 50-100 m (within the depth range of A. kar-
steni) extend several latitudinal degrees beyond the pole-
ward limits of the geographic range of A. karsteni, it
would seem that this species is not making full use of its
thermally defined habitat. Hence, geographic and bathy-
metric restraints on its distribution cannot be principally
thermal. Nor does the restraint appear to be sedimento-
logical, as live specimens of A. karsteni were dredged from
all types of substrate. Factors not considered here, includ-
ing competition, seasonal temperature changes interacting
with the life history of the species, and circulation pat-
terns, may exert more control on the distribution of this
species.

ACKNOWLEDGMENTS

The Los Angeles County Museum of Natural History,
Paleontological Research Institution, and U.S. National
Museum kindly loaned comparative material. J. McLean
and P. Hoover were especially helpful during visits to
their institutions. J. W. Durham brought to my attention
undescribed collections of fossil architectonicids. W. J.
Zinsmeister and C. Macellari offered helpful criticism
during preparation of the manuscript. This work was
supported by NSF grant EAR-8019464 and a Shell Doc-
toral Fellowship. Institute of Polar Studies Contribution
Number 507.

LITERATURE CITED

AppoTt, R. T. 1974. American seashells. 2nd edition. Van
Nostrand Reinhold Co.: New York. 663 pp.

BosE, E. 1906. Sobre algunas faunas terciarias de México.
Instit. Geol. de México Bol. 22:1-96.

BosworTH, T. O. 1922. Geology of the Tertiary and Quater-
nary periods in the northwestern part of Peru. Macmillan
and Co., Ltd.: London. 434 pp.

CossMANN, M. 1915. Essais de paléoconchologie comparée.
Vol. 10. Paris.

DeVries, T. J. 1982. Nearshore depositional sequences of the
Peruvian Mancora Tablazo: prelude to Pleistocene biogeo-
graphic analysis. Geol. Soc. Amer. Abstr. with Progr. 14(7):
474.

D’ORBIGNY, A. 1852. Prodrome de paléontologie stratigra-
phique universelle. Vol. 3. V. Masson: Paris.

FRASSINETTI, D. & V. COVACEVICH. 1981. Architectonidae en
la formacion Navidad, Mioceno, Chile central, parte 2: Ar-
chitectonica (Architectonica) nobilis karstent Rutsch, 1934.
Mus. Nac. Hist. Nat. Bol. 38:147-154.

GARRARD, T. A. 1977. A revision of Australian Architectoni-
cidae (Gastropoda: Mollusca). Records of the Australian
Museum 31(13):506-584.

Gray, J. E. 1847. A list of the genera of recent Mollusca, their
synonyma and types. Proc. Zool. Soc. Lond. 15:129-219.

Gray, M. E. 1850. Figures of molluscous animals. Vol. 4. 124
pp. London.

Junc, P. 1965. Miocene Mollusca from the Paraguana Pen-
insula, Venezuela. Bull. Amer. Paleont. 49(223):385-652.

JuNG, P. 1971. Fossil mollusks from Carriacou, West Indies.
Bull. Amer. Paleont. 61(269):147-262.

KEEN, A. M. 1971. Sea shells of tropical west America. 2nd
edition. Stanford University Press: Stanford, California. 1064
PP-

LAMARCK, J. B. 1822. Histoire naturelle des animaux sans
vertébrés. Vol. 7. Paris. 711 pp. —

LINNE, C. 1758. Systema naturae. 10 ed., reformata 1. Stock-
holm. 824 pp.

Marks, J. G. 1951. Mliocene stratigraphy and paleontology
of southwestern Ecuador. Bull. Amer. Paleont. 33(139):271-
432.

PaTzeRT, W. C. 1978. El Nino watch atlas. Scripps Instit.
Oceanogr. Ref. Ser. No. 78-7. 322 pp.

RODING, P. F. 1798. Museum Boltenianum ...: pars secunda
continens Conchylia .... J. C. Trappii: Hamburg. 109 pp.

RutTscH, R. 1934. Die Gastropoden aus dem Neogen der Pun-
ta Gavilan in Nord-Venezuela. Schweizer. Paldeont. Gesell.
Abh. 54(3):1-88.

Sacco, F. 1892. I molluschi dei terreni terziarii del Piemonte
e della Liguria. Musei di Zool. ed Anat. Comp. della Reale
Univers. di Torino Boll. 7(121):51-57.

Strausz, L. 1966. Die Miozaén-Mediterranen Gastropoden
Ungarns. Akademiai Kiado: Budapest. 535 pp.

TouLa, F. 1908. Eine jungtertiare Fauna von Gatun am Pan-
ama-Kanal. Jahrb. K.K. Geol. Reichsanstalt. 58(1908):673-
760.

TRECHMANN, C. T. 1935. The geology and fossils of Carria-
cou, West Indies. Geol. Mag. 72(12):529-555.

Wooprinc, W. P. 1959. Geology and paleontology of Canal
Zone and adjoining parts of Panama. Description of Ter-
tiary mollusks (Gastropods: Vermetidae to Thaididae). U.S.
Geol. Surv. Prof. Paper 306-B:147-239.

Wooprinc, W. P. 1973. Geology and paleontology of Canal
Zone and adjoining parts of Panama. Description of Ter-
tiary mollusks (Additions to gastropods, scaphopods, pelecy-
pods: Nuculidae to Malleidae). U.S. Geol. Surv. Prof. Paper
306-E:453-539.

The Veliger 27(3):291-307 (January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

The Stenoplax limaciformis (Sowerby, 1832)

Species Complex in the New World

(Mollusca: Polyplacophora: Ischnochitonidae)

by

ROBERT C. BULLOCK

Department of Zoology, University of Rhode Island, Kingston, Rhode Island 02881

Abstract.

The systematic status of species traditionally associated with the Stenoplax limaciformis

species complex of the New World has remained controversial. The group is reviewed and four sibling
species are recognized on the basis of differences in shell sculpture, radular morphology, and esthete
pore density: Stenoplax limaciformis (Sowerby, 1832) from the tropical eastern Pacific, S. purpurascens
(C. B. Adams, 1845) from the West Indies and northern South America, S. floridana (Pilsbry, 1892)
from the Florida Keys south to Colombia, and a long-neglected species, S$. producta (Reeve, 1847), from
the Bahama Islands, Cuba, Jamaica, and Hispaniola south to Honduras and Isla de San Andrés. Two
distinct lineages are recognized within the sibling group: (1) S. floridana and S. producta from the
western Caribbean and (2) the West Indian S. purpurascens and the eastern Pacific S. limaciformis. The
restricted distribution of the Caribbean species within the West Indian Faunal Province, which is
assumed to be a result of a very brief free-swimming larval stage, the insular environment of the area,
and ocean current patterns, lends support to the theory of paraprovincialism as applied to the Caribbean.
Stenoplax floridana and S. producta exhibit a Caloosahatchian distributional pattern, while S. purpur-

ascens reflects a Gatunian origin.

INTRODUCTION

THE CONFUSING nomenclatural history of Stenoplax l-
maciformis (Sowerby, 1832) and the related nominal species
S. purpurascens (C. B. Adams, 1845) and S. floridana
(Pilsbry, 1892) has been presented by Kaas (1972) and
FERREIRA (1978). Taxonomic problems exist due to lim-
ited material available for study, intraspecific variability,
and the small, but consistent, differences exhibited by these
species. The untrained eye, even with the aid of a dis-
secting microscope, may not easily differentiate the species
of Stenoplax.

During the first half of this century two species within
the Stenoplax limaciformis group were recognized: S$. /1-
maciformis from the eastern Pacific and the West Indies,
and S. floridana from the Florida Keys. Kaas (1972), on
the basis of limited and poorly preserved material, con-
cluded that the West Indian populations of “limaciformis”
represent a distinct species, S. purpurascens. ABBOTT (1974)
recorded all three species from Florida and the West In-
dies. After an examination of large samples of these nom-
inal species, FERREIRA (1978) concluded that all of these

Stenoplax “species” are, in fact, a single biological species.
In the most up-to-date listing of Recent polyplacophoran
species, KAAS & VAN BELLE (1980) supported Ferreira
in part, and they synonymized S. purpurascens with S.
limaciformis; however, they retained S. floridana as a dis-
tinct species. I will show in the present study that the S.
lumaciformis complex must be considered as a group of
sibling species. Each of the previously mentioned species
is specifically distinct and, furthermore, a fourth species,
S. producta (Reeve, 1847), also exists in the Caribbean
region.

MATERIALS anpD METHODS

Specimens from the Museum of Comparative Zoology
(Cambridge), the Florida Department of Natural Re-
sources Marine Research Laboratory, and the personal
collections of G. T. Watters (Ohio State University) and
the author were examined in detail. Other material was
available due to the kindness of A. Solem of the Field
Museum of Natural History, T. Hopkins and D. Blizzard
of the Dauphin Island Sea Lab, J. Brooks, D. Dexter, D.

Page 292

Holt, A. Martins, and T. Spight. Photographs of previ-
ously examined type material in the British Museum
(Natural History) and the Museum National d’Histoire
Naturelle, Paris, were available for study.

Only non-eroded specimens were used for the various
aspects of this study. Dry specimens most easily revealed
the small sculptural features necessary for species deter-
mination; preserved or living specimens were blotted with
an absorbent wipe to remove surface liquid.

The shell-plates (valves) of many individuals were dis-
articulated and cleaned using a 2 N solution of KOH.
Specimens to be studied using scanning electron micros-
copy (SEM) were further cleaned in heated KOH solu-
tion and then placed in a series of distilled water rinses
during which they were ultrasonically cleaned. The valves
were then mounted on aluminum specimen stubs using
Duco cement and wedges of aluminum foil. After coating
with carbon and gold/palladium in a Denton DV-502
vacuum evaporator, the samples were studied using an
ISI SEM model MSM-3, located in the Department of
Zoology at the University of Rhode Island.

Examination of numerous SEM photographs revealed
apparent differences in esthete pore density that showed
promise for phylogenetic studies. For this part of the in-
vestigation a total of 41 individuals was selected at ran-
dom. Examples of Stenoplax limaciformis came from Mex-
ico (n= 3) and Panama (n= 10); S. purpurascens from
Puerto Rico (n= 1), the Dominican Republic (n = 1),
Barbados (n= 1), Aruba (n= 1), and Panama (n = 7);
and S. floridana from the Florida Keys (n = 8), Honduras
(n = 1), and Panama (n = 2). For each individual, SEM
photographs of an intermediate valve were made of the
top central area (TC), anterior margin (AM), and lateral
triangle (LT). Each photograph covered 0.145 mm? of the
shell surface. Surface area measurements and esthete pore
counts were taken from 20.3 x 25.4 cm photographic en-
largements. In all TC calculations any portion of the lat-
eral triangle that was visible was excluded from consid-
eration. All area measurements were made using a K &
E compensating polar planimeter. In order to ascertain
the phylogenetic usefulness of these data, percent rib area
(PCTRA), a measure of rib prominence, was plotted
against micropore density (SDEN), megalopore density
(LDEN), and total pore density (TOTDEN) for each
area of the valve. It was evident that LDEN, which rep-
resents the density of megalesthetes, was a more mean-
ingful character than SDEN due to the high degree of
variability in the number of microesthetes associated with
each megalesthete. Further analyses involved only LDEN
for the three areas of the intermediate valve combined.

Canonical variate analysis, using LDEN and PCTRA
as variables, was employed in order to examine the dif-
ferences between the species that were established a priori
on the basis of general shell and radular features. Ma-
halanobis D? distances were calculated for each pair of
species. In canonical variate analysis, variables are trans-
formed to maximize differences between a priori groups

The Veliger, Volj 27sNows

relative to within group variation (NEFF & Marcus, 1980;
CAMPBELL & ATCHLEY, 1981). This form of analysis has
been shown to be an invaluable tool in the analysis of
variation between populations, groups of populations, and
species. All computations were carried out using the SAS
program at the Academic Computer Center at the Uni-
versity of Rhode Island.

The valves selected for line drawings were taken from
individuals used for SEM studies. These valves were
mounted on large pins and coated with magnesium oxide
in order to enhance sculptural detail.

Radulae and girdle elements were briefly examined us-
ing SEM techniques; however, most samples were more
easily studied using light microscopy. Permanent micro-
slide mounts were prepared by dehydrating in ethanol,
clearing in toluene, and mounting in Canada balsam.

The radulae were excised, thoroughly cleaned, and
teased apart before study. The many small differences
noted in denticle cap morphology were best seen in an
outline view of the cap; for each preparation a portion of
the radula was teased apart enough to separate some den-
ticle caps from major lateral teeth. In specimens that had
been preserved for more than a few years, this posed no
substantial problem because there was a tendency for the
denticle caps to fall off during the cleaning stages. The
caps, due to their magnetic property, were collected on
the tip of an insect pin and transferred to the mounting
medium. The radulae of 69 individuals were examined in
detail by light microscopy (Stenoplax limaciformis, 6; S.
purpurascens, 7; S. floridana, 29; S. producta, 27). The
radulae of 139 other individuals were isolated, cleaned,
and observed, but not mounted.

Girdle scales were studied using cleaned, isolated scales.
Because of the great amount of variation between girdle
scales, the marginal spicules, and the small ventral scales
of the same specimen, preparations were made by taking
a small sample (about a fourth of the animal length, on
one side in the middle) and processing it as a unit. The
scales often separated, especially during ultrasonic clean-
ing, but they were pipetted and transferred to a microslide
using a small, disposable Pasteur pipet. The scales were
allowed to settle in the pipet in order to concentrate them.
The filmlike folded sheet of ventral scales and the re-
mainder of the dorsal scales were then added to the slide
before the Canada balsam was applied. The small, rect-
angular scales of the ventral surface of the girdle were so
similar among the species examined that descriptions of
them are not included in the present study. Therefore, all
references to “girdle scales” refer to the dorsal scales and
the outer fringe of spicules.

ABBREVIATIONS

The following institutions and individuals are cited in the
text using the abbreviations listed below:

ANSP—Academy of Natural Sciences of Philadelphia
BLM—Bureau of Land Management

~R. C. Bullock, 1985

BMNH—British Museum (Natural History), London

DISL—Dauphin Island Sea Lab, Alabama

FDNR—Florida Department of Natural Resources Ma-
rine Laboratory, St. Petersburg

FMNH—Field Museum of Natural History, Chicago

GTW—Collection of G. T. Watters

MCZ—Museum of Comparative Zoology, Cambridge

MNHNP—Museum National d’Histoire Naturelle, Paris

RCB—Collection of R. C. Bullock

SDSC—San Diego State College

SYSTEMATIC SECTION
Family ISCHNOCHITONIDAE Dall, 1889
Subfamily ISCHNOCHITONINAE Dall, 1889

The systematics of polyplacophorans at the family and
subfamily levels are greatly in need of revision. I follow
the conservative approach presented by Kaas & VAN
BELLE (1980), who included in the Ischnochitoninae the
genera Ischnochiton Gray, 1847, Stenoplax Dall, 1879,
Stenochiton H. Adams & Angas, 1864, Lepidozona Pils-
bry, 1892, and Connexochiton Kaas, 1979. The only recent
review of the subfamily is that of VAN BELLE (1977).

Genus Stenoplax (Carpenter MS) Dall, 1879

Type species: Chiton limaciformis Sowerby, 1832 by orig-
inal designation.

There is a difference of opinion concerning the author-
ship of Stenoplax and other names proposed in the large
unpublished chiton manuscript of P. P. Carpenter and
later properly introduced by DALL (1879), PitsBry (1892-
1894), and others. SMITH (1960), KEEN (1971), FERREIRA
(1978), and various west coast workers have consistently
assigned authorship to Carpenter. DaALL (1879) and
PILsBRY (1892-1894) credited Carpenter where they took
information directly from the manuscript. The manu-
script, housed in the Division of Mollusks at the U.S.
National Museum of Natural History, is in two large
scrapbooks. Much of the writing is in curious shorthand.
Given the condition of the manuscript, it seems to me
incredible that Carpenter should be considered as having
published these names in the meaning of the International
Code of Zoological Nomenclature. I follow Boss e¢ al.
(1968) and assign the authorship to the person who val-
idly introduced the name in question.

The genus Stenoplax was introduced (DALL, 1879:78)
on the same page as Stenoradsia. The latter name is cur-
rently accepted as a subgenus of Stenoplax s./. (SMITH,
1961; VAN BELLE, 1977; Kaas & VAN BELLE, 1980).
SMITH (1961) also listed Stenochiton Adams & Angas,
1864, as a subgenus of Stenoplax, but Australian workers
(cof. ASHBY, 1918; IREDALE & HULL, 1927) and VAN BELLE
(1977) have considered Stenochiton a separate genus.
Should this genus of elongate, Stenoplax-like chitons be
considered congeneric with Stenoplax, the name Stenochi-
ton would have precedence.

Page 293

When DALL (1879) introduced the genus Stenoplax, he
listed the type species as “‘S. limaciformis Sby.” It seems
inconceivable that Dall, or Carpenter who had no doubt
seen type specimens in the British Museum, could have
misidentified such a well known species; but the only in-
formation presented by Dall, including his figure (pl. 2,
fig. 13), does not coincide with features of S. limaczformis
or any other Stenoplax s.s. Dall stated that the central
tooth is very small and that the major lateral tooth has a
simple cusp. In fact, all Stenoplax s.s. have a tricuspidate
denticle cap (THIELE, 1893; TAkI, 1954; this paper), and
the central tooth is moderately narrow but certainly not
“small” as Dall stated. In spite of this discrepancy, the
use of the name Stenoplax has not been questioned.

Stenoplax Dall s.s.

Description: Animal elongate, of medium size, reaching
a length of about 50 mm. Color highly variable. Valves
moderately flattened to inflated. Sculpture of anterior valve
and posterior slope of posterior valve granular, nodulose,
or of concentric ribs; in some forms the granules or nod-
ules coalesce to form radial or concentric sculpture. Cen-
tral areas and jugum with longitudinal ribs which may
break up into pustules near the lateral triangle. Mucro of
posterior valve central or posteriorly acentric. Slitting of
insertion plates highly variable within each species; an-
terior valve with 8-14 slits, posterior valve with 7-12 slits;
intermediate valves with one slit per side. Dorsal girdle
scales very small, typically about 120 um high, 80 um
wide, with 9-19 ribs per scale; ribs may or may not reach
apex. Denticle cap of major lateral tooth tricuspidate.

Stenoplax s.s. includes: S. limaciformis (Sowerby, 1832)
from the eastern Pacific; S$. purpurascens (C. B. Adams,
1845), S. floridana (Pilsbry, 1892), and S. producta (Reeve,
1847) from the western Atlantic; and S. venusta (Is. & Iw.
Taki, 1931) and S. alata (Sowerby, 1841) from the Indo-
Pacific region. Ischnochiton kempfi Righi, 1971, from Bra-
zil is also a Stenoplax, but Kaas & VAN BELLE (1980)
considered it a member of the subgenus Stenoradsia; its
relationship to Stenoplax s.s., especially the S. floridana-S.
producta lineage, needs to be investigated, but material is
presently unavailable. Some other New World species may
be properly placed in Stenoplax s.s. For example, S. boogi
(Haddon, 1886) appears to be a Stenoplax, but it does not
belong to the S. limaciformis group. ABBOTT (1974) in-
cluded Ischnochiton erythronotus (C. B. Adams, 1845) in
Stenoplax, but FERREIRA (1978) noted that this species is
a junior subjective synonym of Ischnochiton striolatus (Gray,
1828) which is not considered a Stenoplax.

I have found that the girdle scales of Stenoplax s.s. po-
larize light. Whether there is any adaptive significance to
this crystalline structure of calcium carbonate is unknown.

The biology of Stenoplax s.s. species is poorly known.
Anatomical observations were reported by PLATE (1901)
who studied S. alata from the Philippine Islands. It is
generally thought that polyplacophorans are herbivorous

Page 294

Figure 1

Stenoplax limaciformis (Sowerby). Punta Mala, Panama (RCB).
A, anterior valve. B, right portion of intermediate valve. C, pos-
terior valve. Scale bar = 1 mm.

(HyMaNn, 1967), but some chitons are definitely omnivo-
rous if not carnivorous (BARNAWELL, 1960; MCLEAN,
1962; Thorpe in KEEN, 1971). Stenoplax appears to fall
into the latter category. PLATE (1901) found foraminif-
erans in the gut of S. alata. RAEIHLE (1967) reported that
aquarium-kept §. floridana feed on mussel meat.
Stenoplax s.s. lives in a fairly restricted habitat. In a
note on a label for S. limaciformis, a collector noted that it
was found living “buried on sides of deeply bedded rocks.”
Caribbean species also live on rocks embedded in the sub-
strate. In all cases, the rocks must actually be embedded,
not just be resting on other rocks, and the substrate is
usually clean, coarse sand or gravel. The species are ab-
sent in silty areas or in anaerobic substrates. Species of
Stenoplax s.s. typically inhabit shallow waters from the
low tide mark to a depth of a few meters. They are known
to occur in deeper water as records from the western coast

The Veliger, Vol. 27, No. 3

of Florida and the Bahamas attest. RIGHI (1971) obtained
specimens of S. purpurascens from as deep as 90 m.

Key to the species of the
Stenoplax limaciformis species complex

1. Ribs of central areas conspicuously broken into
pustules near lateral triangle; lateral triangle
usuallyseranular a eee eee S. floridana

Ribs of central areas forming few, if any, pustules;
lateral triangle with concentric ribs which may
be broken into broad nodules .............. 2

2. Posterior valve elongate; mucro posteriorly acen-

tric; microfurrows, visible under high magnifi-

cation, in all’grooves! )3 eee S. producta
Posterior valve not elongate; mucro centrally lo-
cated; groovessmooth! = 455 n eee 3
3. Anterior valve and posterior slope of posterior valve
with wavy, concentric ribs ....... S. purpurascens
Anterior valve and posterior slope of posterior valve
with nodular sculpture .......... S. limaciformis

Stenoplax limaciformis (Sowerby, 1832)
(Figures 1-7, 8A, B, 9A)

Chiton limaciformis Sowerby in BRODERIP & SOWERBY, 1832:
26 (Inner Lobos Island in Peru and Guacomayo in
Central America; holotype in BMNH); REEVE, 1847:
pl. 8, sp. 42.

Chiton (Ischnochiton) lmaciformis Sowerby. SHUTTLEWORTH,
1853:190.

Stenoplax limaciformis (Sowerby). DALL, 1879:78; KEEN,
1958:526, fig. 44; Thorpe in KEEN, 1971:871, sp. 24;
ABBOTT, 1974 [in part]:396; FERREIRA, 1978 [in part]:
87; KAAS & VAN BELLE, 1980:74.

Ischnochiton (Stenoplax) limaciformis (Sowerby). PILSBRY,
1892:57, pl. 16, figs. 9-16.

Chiton angustus CLESSIN, 1904:120, pl. 41, fig. 1 (Central
America; location of type unknown).

Ischnochiton limaciformis (Sowerby). PILSBRY & Lowe, 1932:
129; Kaas, 1972:71.

Description: Animal reaching a length of 45 mm, elon-
gate. Anterior valve with concentrically arranged nodules,
but occasionally nodules coalesce to form radially ar-
ranged groups of nodules; insertion plate with 9-13 slits.
Intermediate valves rounded; longitudinal ribs of central
area about as wide as intervening grooves and bend lat-
erally; ribs become irregular near lateral triangle; ribs of
jugum close-packed. Lateral triangle with broad close-
packed concentric ribs which at times are broken to give
a slightly nodular appearance. One slit per side in inser-
tion plate. Posterior valve with central mucro; central areas
with sculpture like that of intermediate valves; posterior
slope sculpture similar to that of anterior valve; insertion
plate with 7-12 slits.

Girdle scales slightly curved, variable in proportions,
but typically about 102 wm long, 87 um wide; 10-19 ribs
per scale; ribs reach apex. Girdle fringe with straight,
ribbed spicules, approximately 120 um in length.

R. C. Bullock, 1985

Explanation of Figures 2 to 7

Scanning electron micrographs of intermediate valve sculpture of Stenoplax limaciformis (Sowerby)., Posterior side
toward top of page; all photographs 186. Figures 2 to 4: Punta Mala, Panama (RCB). Figures 5 to 7: Acapulco,
Mexico (MCZ 204170).

Figures 2, 5. Posterior region of central area near lateral triangle. Note the large number of esthete pores on the
ribs, the lack of groove microsculpture, and that the ribs become irregular, but that they do not break into pustules.

Figures 3, 6. Central area near anterior margin.

Figures 4, 7. Lateral! triangle.

Page 296

The Veliger, Vol. 27, No. 3

Ge 7

Figure 8

Representative denticle caps of the major lateral radular tooth of New World species of the Stenoplax limaciformis

complex.

A and B, S. limaciformis: A, Playa Caleta, Acapulco, Mexico (RCB); B, Punta Mala, Panama (RCB).
C and D, S. producta: C, Anthonys Key, Roatan Id., Honduras (RCB); D, Harbour Island, Eleuthera, Bahama

Islands (GTW).

E and F, S. purpurascens: E, Bridgetown, Barbados (RCB); F, North side of Galeta Id., Panama (RCB).
G and H, S. floridana: G, Verde Id., Mantilla Pt., Porto Bello, Panama (RCB); H, Indian Key Fill, Florida Keys,

Florida (RCB). Scale bar = 50 um.

Radula typical for subgenus. Denticle cap of major lat-
eral tooth tricuspidate, rather squat; small cusp moder-
ately pronounced; side with small cusp swollen; brown
basal spot present.

Remarks: Stenoplax limaciformis seems to be most closely
related to S. purpurascens. Both species have blunt cusps
and a brown basal spot on the denticle cap, and both
exhibit rather broad ribs with many esthete pores on the
central areas. Neither species has any break-up of the
central area ribs into pustules. The more even, wavy, con-
centric ribs of the anterior valve and the posterior slope
of the posterior valve separate S. purpurascens from S.
lumaciformis. The denticle caps of the two species are quite
different: in S. purpurascens the small cusp is much more
pronounced than in S. limaciformis, and the outline of the
denticle cap on the side of the small cusp is never swollen
as it always is in S. lumaciformis (Figures 8A, B, E, F).
For additional comments about the relationship between
S. limaciformis and S. purpurascens, see the remarks for
the latter species.

Distribution: Stenoplax limaciformis occurs from Puerto-
citos and La Libertad, Mexico, south to Peru (Thorpe, in
KEEN, 1971) (Figure 9A).

Specimens examined: Mexico: San Luis Gonzaga; Ma-
zatlan (both MCZ); Isla Pajaros, Mazatlan (SDSC); Aca-
pulco (MCZ, RCB).—Costa Rica: Playas del Coco
[10°31’N, 85°43’W] (RCB).—Panama: Punta Mala; Naos
Id.; Culebra Id.; W side of Taboga Id.; W side of Morro
de Taboga, Taboga Id.; E side of Taboga Id., near Urava
Id. (all RCB).

Stenoplax purpurascens (C. B. Adams, 1845)
(Figures 8E, F, 9A, 10-13)

Chiton purpurascens C. B. ADAMS, 1845:9 (Jamaica; holo-
type MCZ 155962); CLENCH & TURNER, 1950:334, pl.
42, fig. 2 [holotype figured].

Chiton sanguineus REEVE, 1847:pl. 17, sp. 98 (St. Vincent,
W. Indies, holotype in BMNH).

Chiton (Ischnochiton) purpurascens C. B. Adams.
SHUTTLEWORTH, 1853:199.

Onitochiton [sic] pruinosum ROCHEBRUNE, 1884:35 (Ile
Cochino, Guadeloupe; type in MNHNP).

Ischnochiton (Stenoplax) limaciformis (Sowerby). DALL, 1889:
415 [in part]. Non Stenoplax limaciformis (Sowerby).

Ischnochiton limaciformis (Sowerby). PILSBRY, 1892:57 [in
part]; DALL & Simpson, 1901:452; WARMKE & ABBOTT,
1961:217, text fig. 32e; RIGHI, 1971:126, figs. 13-18;
GOTTING, 1973:248, pl. 9, fig. 5; Rios, 1975:265;

SRC) Bullock, 1985

Page 297

Figure 9

Known distribution of species of the Stenoplax limaciformis complex in the New World. A, S. limaciformis (Wl) and
S. purpurascens (@). B, S. floridana. C, S. producta. Closed marks represent specimens examined; open marks

indicate localities taken from the literature.

Humrrey, 1975:290, fig. 18d. Non Stenoplax limacifor-
mis (Sowerby).

Stenoplax producta (Reeve). THIELE, 1909:7. Non Stenoplax
producta (Reeve).

Ischnochiton productus (Reeve). THIELE, 1910a:80; THIELE,
1910b:110. Non Stenoplax producta (Reeve).

Ischnochiton purpurascens (C. B. Adams). ABBOTT, 1954:
320; ABBOTT, 1958:108.

Stenoplax purpurascens (C. B. Adams). ABBOTT, 1974:396
[erroneously reported from the Florida Keys and Ber-
muda].

Stenoplax limaciformis (Sowerby). FERREIRA, 1978 [in part]:
87; Kaas & VAN BELLE, 1980 [in part]:74. Non Steno-
plax limaciformis (Sowerby).

Description: Animal reaching a length of 45 mm, elon-
gate. Color variable with pink or green predominating;

valves often streaked or speckled with darker or lighter
colors. Anterior valve with broad, close-packed, wavy,
concentrically arranged ribs; insertion plate with 9-13 slits.
Intermediate valves somewhat flattened to quite inflated;
ribs of central areas wider than intervening grooves and
bend laterally; ribs becoming irregular, but not broken
into pustules near lateral triangle; longitudinal ribs of
jugum fine, close-packed, directed anteriorly; lateral tri-
angle with broad, slightly oblique, concentric ribs; inser-
tion plate with one slit per side. Posterior valve with cen-
tral mucro; central areas with sculpture like that of
intermediate valves; posterior slope with sculpture of lat-
eral triangle, but slightly more irregular; insertion plate
with 8-11 slits.

Girdle scales 120-150 um high, about 95 wm wide; 15-

Page 298

Figure 10

Stenoplax purpurascens (C. B. Adams). North side of Galeta Id.,
Panama (RCB). A, anterior valve. B, right portion of interme-
diate valve. C, posterior valve. Scale bar = 1 mm.

23 ribs per scale; ribs may or may not reach apex. Girdle
fringe with straight, ribbed spicules approximately 97 um
long.

Radula typical for subgenus. Denticle cap of major lat-
eral tooth tricuspidate, moderately squat; small cusp pro-
nounced; all cusps blunt; brown basal spot present.

Remarks: There is much confusion in the literature about
the relationship between the eastern Pacific S. limaciformis
and the West Indian S. purpurascens. Sowerby’s specimens
were from Inner Lobos Island, Peru, and Guacomayo
[southern Chiapas, Mexico, fide KEEN (1971)]. The gen-
eral description given by Sowerby (in BRODERIP &
SOWERBY, 1832) and the lack of specimens in museum
collections certainly contributed to taxonomic chaos. DALL
(1889) and PiLsBry (1892:57) both used Sowerby’s name
for the western Atlantic species that is herein recognized

The Veliger, Vol. 27, No. 3

as S. purpurascens. Pilsbry concluded that “the West In-
dian specimens collected by Robert Swift at St. Thomas
and the Peruvian specimens which I have examined are
absolutely identical in character ....” THIELE (1909,
1910a) studied shell and girdle scale morphology of these
species and he concluded that the West Indian species is
not conspecific with S. limaciformis. Thiele’s work, how-
ever, was ignored by American authors who continued to
follow Pilsbry. ABBOTT (1954), KEEN (1958), and Thorpe
(in KEEN, 1971), for example, all stated that S. limaczfor-
mis occurs in the Caribbean. Kaas (1972), who noted
“rather striking differences between the two species,” cor-
roborated Thiele’s earlier findings and he used the name
Ischnochiton purpurascens (C. B. Adams) for the West In-
dian species. The culmination of this confusion is seen in
ABBOTT’s (1974) second edition of American Seashells in
which he recorded both S. limaciformis and S. purpurascens
from the western Atlantic.

FERREIRA (1978) was the first person to study large
samples of New World Stenoplax from various localities.
In his report on the status of the polyplacophoran species
described from Jamaica by C. B. Adams, Ferreira ex-
amined the West Indian “limaciformis” problem in some
detail. He concluded that differences in shell, girdle, and
radular features do not warrant the use of the names S.
floridana or S. purpurascens. FERREIRA (1978:88) found
“many intergradations in the described tegmental sculp-
tures, and many forms of transition between ‘floridanus’
and ‘limaciformis’ often in specimens found side by side at
the same collection station.” At the time Ferreira pub-
lished his results, I was just beginning to examine Steno-
plax specimens from Honduras and the Caribbean coast
of Panama. I did not immediately see intergradations be-
tween S. floridana and S. purpurascens, and I therefore
began a study that would allow me to decide indepen-
dently the status of these nomina. My investigation began
by using scanning electron microscopy to obtain high mag-
nification photographs of the dorsal shell sculpture. Other
parts of the investigation were devoted to an examination
of the girdle elements and radulae using light microscopy.

I have concluded that Stenoplax limaciformis, S. purpur-
ascens, and S. floridana are closely related but specifically
distinct; furthermore, a third Caribbean species, S. pro-
ducta (Reeve, 1847), exists. I can state that the reason that
FERREIRA (1978) found differing entities “side by side at
the same collecting station” is that each different western
Atlantic species occurs sympatrically with another mem-
ber of the group over a part of its range. Light microscopy
of shell features, especially using glistening, alcohol-pre-
served specimens, can lead to confusion. But SEM studies
of the shell and a study of denticle cap morphology have
allowed the recognition of the subtle differences that char-
acterize each member of this group of sibling species.
Knowledge of these differences readily allows one to iden-
tify the species using a dissecting microscope.

Stenoplax purpurascens is more closely related to the
eastern Pacific §. limaciformis than to S. floridana or S.

R. C. Bullock, 1985 Page 299

iJ

ia)

Explanation of Figures 11 to 16

Scanning electron micrographs of intermediate valve sculpture of Stenoplax purpurascens (C. B. Adams) and S.
producta (Reeve). Posterior side toward top of page; all photographs 186. Figures 11 to 13: S. purpurascens, Porto
Bello, Panama (RCB). Figures 14 to 16: S. producta, Nassau, New Providence Id., Bahama Islands (GTW).

Figures 11, 14. Posterior region of central area near lateral triangle. Note the tendency for the ribs of S. producta
to break into pustules near the lateral triangle, and the furrowlike sculpture in the intervening grooves.

Figures 12, 15. Central area near anterior margin. Note the low density of esthete pores on the ribs of S. producta.
Figures 13, 16. Lateral triangle.

Page 300

The Veliger, Vol. 27, No. 3

Table 1

Esthete pore density and rib area measurements of members of the Stenoplax limaciformis species complex. All figures
+ SD. ‘Total’? numbers derived from mean of each individual. See text for further explanations.

x SDEN/mm?
S. limaciformis TC 6348 + 1210
(n = 13) AM 5349 + 949
LT 6383 + 1151
Total 6021 + 984
S. purpurascens TC 6798 + 1177
(n = 11) AM 5872 + 652
lye 7505 + 1166
Total 6753 + 609
S. floridana TC 4821 + 636
(n = 11) AM 2690 + 843
LT 5499 + 862
Total 4405 + 719
S. producta TC 3706 + 869
(n = 6) AM 2348 + 1144
LT 5037 + 1215
Total 3790 + 1013

producta with which it occurs sympatrically over parts of
its range. Both S. purpurascens and S. limaciformis have a
centrally located mucro on the posterior valve and ribs on
the central areas that do not form pustules near the lateral
triangle. In addition, these ribs are broader and they have
a much higher density of esthete pores than in S. producta
and, especially, S. floridana (Table 1). The broadness of
the ribs may be quantified by the area of the valve (as a
percent) covered by ribs (PCTRA; see Table 1). All species
except S. floridana have more than 50% of the intermediate
valve covered by ribs; S. purpurascens has much higher
values for PCTRA than the other species. Canonical vari-
ate analysis using the density of the megalopores (LDEN)
and percent rib area (PCTRA) as variables reveals that
two groups of the S. limaciformis species complex exist:
one group is composed of S. limaciformis and S. purpur-

Table 2

Mahalanobis D? distance values between members of the

Stenoplax limaciformis species complex. The distance val-

ues are in the upper triangle and probability values in the

lower triangle. LIM = S. limaciformis, PUR = S. purpur-

ascens, FLO =S. floridana, PRO = S. producta. See text
for further explanations.

Species LIM PUR FLO PRO

LIM _ 1.94 5.89 4.61
PUR <0.001 — 7.14 5.41
FLO <0.001 <0.001 — 2.19
PRO <0.001 <0.001 <0.05 —

x LDEN/mm? x TOTDEN/mm? x PCTRA
1388 + 299 7736 + 1369 59.4 + 6.6
1248 + 162 6597 + 996 56.0 + 8.5
2086 + 305 8469 + 1306 68.8 + 6.2
1611 + 223 1633 = MN123 61.5 + 6.1
1278 + 128 8075 + 1222 68.9 + 7.1
1166 + 157 7037 + 678 OGY) a5 B77
2089 + 422 9494 + 1286 YD = DY
1524 + 166 8277 + 685 Wild as Gets)

94 Oe EielSi ey/71A0) a2 7/Sy7 47.9 + 7.6
566 + 128 3257 + 898 43.5 + 6.4
1119 + 239 6618 + 1051 54.8 + 4.3
894 + 163 5300 + 832 48.6 + 4.4
904 + 114 4610 + 962 56.4 + 3.4
oes sls} 2860 + 1260 56.6 + 7.4
LIS Sy=Ev139 6192 + 1326 64.7 + 9.7
875 + 118 4665 + 1121 by).3) 2= D0)

ascens while the other group consists of S. floridana and
S. producta. The Mahalanobis D? distances, which reflect
the distance between the centroids of each species, are
much greater between these two groups than within each
group (Table 2).

Both Stenoplax limaciformis and S. purpurascens have a
brown basal spot on the denticle cap of the major lateral
tooth. The denticle cap of S. purpurascens differs consid-
erably by lacking the bulging outline along the side with
the small cusp, and the small cusp is more prominent
(Figures 8E, F). The species also differ in the sculpture
of the lateral triangle, the anterior valve, and the posterior
slope of the posterior valve. In S. purpurascens this sculp-
ture typically is of rather flat, wavy, concentric ribs,
whereas in S. limaciformis there is a much greater tenden-
cy for these ribs to be broken into broad nodules, espe-
cially on the end valves.

When compared with the other Caribbean species,
Stenoplax purpurascens differs by its central, not poste-
riorly acentric, mucro on the posterior valve, and by wavy
concentric ribs on the anterior valve. In both S. florzdana
and S. producta the anterior valve is granular, although
some specimens of the latter species from 18 m at Gold
Rock, Grand Bahama Island (FDNR 30416) interesting-
ly differ in this respect and exhibit concentric sculpture.
The lateral triangle of S. producta has concentric ribs, as
does S. purpurascens, but the ribs in the former are typi-
cally more narrow, and they are parallel to the antero-
posterior axis, rather than slightly oblique to it. The char-
acteristic furrowlike sculpture in the grooves of S. producta
(Figures 14-16), visible under high magnification in non-
eroded specimens, serves to differentiate the species from

R. C. Bullock, 1985

S. purpurascens and other Stenoplax s.s. Both S. floridana
and §. producta have a more elongate denticle cap on the
major lateral tooth, the two larger cusps are more pro-
nounced, and the brown basal spot, seen in S. purpuras-
cens, is absent (Figures 8C, D, G, H).

FERREIRA (1978) mentioned that he had observed “many
forms of transition” between members of the Caribbean
limaciformis group. He did not state the localities where
he had observed this phenomenon, but it is likely that he
had encountered examples of either Stenoplax producta,
which previous authors have not recognized, or some of
the interesting intraspecific variation exhibited by S. flor-
dana. Stenoplax purpurascens occurs sympatrically with S.
floridana in the southern Caribbean (Panama and Colom-
bia); it lives with S$. producta in Cuba, Hispaniola, and
Jamaica. In these cases I did not observe any intergra-
dation; the shell sculpture indicated one species or the
other, and these conclusions were consistently supported
by SEM analysis of valve microsculpture and light mi-
croscopic observation of the radula.

Distribution: Stenoplax purpurascens occurs from Cuba
and Hispaniola south and east through the Caribbean to
Panama, the northern coast of South America, and Brazil
(Figure 9A).

Specimens examined: Cuba: Gibara; Santiago (both
GTW).—Jamaica: Montego Bay (MCZ); 2 mi (3.2 km)
W of Runaway Bay, 1-1.5 m; along seawall, just W of
Runaway Bay, 0.15-1 m (both RCB); Port Henderson
(GTW).—Haiti: Miragoane (MCZ).—Dominican Re-
public: Santa Barbara de Samana (MCZ); small cove just
E of Embassy Beach, 16 km E of Boca Chica, 0.5-2 m;
Isla La Matica, Playa Boca Chica, 0.5-1 m (both RCB).—
Puerto Rico: Phosphorescent Bay; Magueyes Id., La Par-
guera; Cayo Enrique, La Parguera (all RCB); Arrecife
Media Luna 2.25 mi (3.6 km) S of La Parguera (MCZ);
Cabo Rojo Lighthouse (RCB); Playa Sucia, Cabo Rojo
(MCZ).—Virgin Islands: Water Id., St. Thomas; St. Croix
(both GTW); The Bight, Norman Id., 1-5 ft (0.3-1.5 m)
(MCZ).—Antigua: Falmouth Harbour; Hawkes Bill Bay
(both RCB).—St. Lucia: Vieux Fort (MCZ).—Barbados:
Archers Bay, St. Lucy; Bridgetown (both RCB).—Toba-
go: (MCZ).—Trinidad: Maguaripe Beach, 1.5-3 m
(RCB).—Aruba: Commanders Bay (RCB).—Panama:
Toro Pt., ocean side (RCB); Galeta Id. (GITW, RCB);
Reef off Cocal Pt., Porto Bello; Porto Bello (both RCB).—
Venezuela: Cayo Punta Brava, Parque Nacional de Mor-
rocoy, Tucacas (RCB).

Stenoplax floridana (Pilsbry, 1892)
(Figures 8G, H, 9B, 17-23)

Ischnochiton (Stenoplax) limaciformis (Sowerby). DALL, 1889:
415 [in part]. Non Stenoplax limaciformis (Sowerby).

Ischnochiton (Stenoplax) floridanus PILSBRY, 1892:58, pl. 17,
figs. 19-22 (Key West, Florida; holotype ANSP 35694).

Page 301

Figure 17

Stenoplax floridana (Pilsbry). Just north of Crawl Key, Florida
Keys, Florida (RCB). A, anterior valve. B, right portion of in-
termediate valve. C, posterior valve. Scale bar = 1 mm.

Ischnochiton floridanus Pilsbry. JOHNSON, 1934:13; ABBOTT,
1954:320; GOTTING, 1973:248, pl. 9, fig. 5.

Stenoplax floridana (Pilsbry). ABBOTT, 1974:396, fig. 4653;
EMERSON & JACOBSON, 1976:464; TURGEON & Lyons,
1977:88; Kaas & VAN BELLE, 1980:48.

Stenoplax limaciformis (Sowerby). FERREIRA, 1978 [in part]:
87.

Description: Animal reaching a length of 50 mm, elon-
gate. Color highly variable, but typically cream white with
small dark green speckles. Anterior valve granular; small
nodules may be radially or concentrically arranged, de-
pending on growth lines; insertion plate with 8-11 slits.
Intermediate valves moderately inflated, angular; longi-

The Veliger; Volh27- Noms

Page 302

Explanation of Figures 18 to 23

Florida (RCB). Figures 21

5)

, Florida Keys

Fill

Scanning electron micrographs of intermediate valve sculpture of Stenoplax floridana (Pilsbry). Posterior side toward
all photographs 186x. Figures 18 to 20: Indian Key

top of page;

to 23: North side of Galeta Id., Panama (RCB).

Figures 18

Note that the ribs are conspicuously broken
, and the lack of pronounced sculpture in the

21. Posterior region of central area near lateral triangle.

>

into pustules, the sparseness of esthete pores on the ribs and pustules

intervening grooves.

Figures 19, 22. Central area near lateral triangle.

Figures 20, 23. Lateral triangle.

R. C. Bullock, 1985

Figure 24

Stenoplax producta (Reeve). Arthur’s Town, Cat Id., Bahama
Islands (MCZ 279211). A, anterior valve. B, right side of inter-
mediate valve. C, posterior valve. Scale bar = 1 mm.

tudinal ribs of jugum fine, directed anteriorly; ribs of cen-
tral areas typically not as wide as intervening grooves,
directed laterally; ribs broken into ovate to round pustules
near lateral triangle; insertion plate with one slit per side.
Lateral triangle sharply raised, with numerous small nod-
ules which may be radially arranged or appear to be con-
centrically arranged due to heavy growth lines or slight
coalescing of nodules. Posterior valve elongate; mucro pos-
teriorly acentric; jugal area reduced; central area sculpture
as in intermediate valves; posterior slope sculpture as in
anterior valve; insertion plate with 8-12 slits.

Girdle scales about 100-125 um long, 77-93 um wide,
9-13 ribs per scale; ribs reach apex in some populations
but conspicuously do not in other populations. Girdle fringe
with straight, ribbed spicules 77-89 wm in length.

Page 303

Radula typical for subgenus. Denticle cap of major lat-
eral tooth tricuspidate, rather elongate; small cusp pro-
nounced, all cusps pointed; outline of side with small cusp
often quite straight occasionally inwardly curved; brown
basal spot absent (Figures 8G, H).

Remarks: Stenoplax floridana is the most easily distin-
guished member of the S. limaciformis group. The consis-
tent break-up of the longitudinal ribs of the central area
near the lateral triangle into pustules allows instant rec-
ognition. The valve surface of S. floridana has much less
surface area covered by ribs than the other species (Table
1). This reduction is due not only to the narrowness of
the ribs but to the break-up of the ribs into pustules in
the top central (TC) and lateral triangle (LT) areas. Al-
though the ribs of S$. floridana have a lower density of
esthete pores than S. limaciformis or S. purpurascens, the
density is higher than that observed in S. producta.

Long thought to be restricted to the Florida Keys, the
species extends southward to the northern coast of Colom-
bia (GOTTING, 1973). Stenoplax floridana differs from S.
purpurascens, with which it occurs sympatrically along the
Caribbean coast of Panama and Colombia, by its more
sharply raised lateral triangle which is granular, not with
broad concentric ribs. Also, S$. purpurascens never exhibits
a break-up of the central area ribs into pustules. The
denticle cap of the two species differs considerably: in S.
floridana the denticle cap is more elongate, and an outline
of the cap usually shows a straight side below the small
cusp; the cusps of §. floridana are more pronounced and
more pointed than those of S. purpurascens (Figures 8G,
H). Stenoplax floridana lacks the brown basal spot of the
denticle cap that is so characteristic of S. purpurascens and
S. limaciformis. Some authors have noted that the girdle
scales of the two species may be used as a differentiating
character (PILSBRY, 1892; THIELE, 1910a; Kaas, 1972).
There seems to be much intraspecific variation, often ex-
pressed on a geographic basis, in girdle scale morphology.
Early in my investigation when I had sampled the scales
of only a few individuals, I had also concluded that the
girdle scales were taxonomically useful, but I now feel
that statements concerning girdle scale differences must
be made with caution. Scales of typical S. floridana from
the Florida Keys have fewer ribs (9-12) than West Indian
S. purpurascens (15-18); I never observed a rib count as
low as that stated by Kaas (1972) who found 8 ribs. In
the Florida Keys the ribs do not reach the apex, as Kaas
noted, but this feature is certainly not true for populations
of S. floridana from Honduras and Panama. Similarly, the
girdle scales in some populations of $. purpurascens have
ribs that do not reach the apex while other populations
differ in this respect.

Stenoplax floridana is most likely to be confused with
the previously overlooked S$. producta (Reeve). Usually
both species have a granular anterior valve and both often
have thin ribs on the central areas; in S. producta these
ribs occasionally show a slight break-up into pustules, but
pustular formation is minimal. The lateral triangle of S.

Page 304

producta has well developed concentric ribs whereas in S.
floridana the lateral triangle is granular with the granules
sometimes coalescing to form nodular radial ribs. In some
specimens from Dry Tortugas and Key Largo, the gran-
ules partially coalesce to form irregular concentric ribs.
Also, while some S. floridana have faint microscopic fur-
rows in the intervening grooves, this feature is highly ex-
aggerated in S. producta. The radular denticle cap of the
two species differs considerably: in S. floridana the small
cusp is pronounced and the remaining two cusps are elon-
gated and pointed, whereas in S. producta the small cusp
is often reduced and the other two cusps are broad and
blunt (Figures 8C, D, G, H).

Distribution: Stenoplax floridana occurs from the offshore
waters of the western coast of Florida to the Florida Keys
and south to Honduras, Panama, and Colombia. The rec-
ord from Nassau in the Bahama Islands has not been
confirmed by recent collecting and it may be in error (Fig-
ure 9B).

Specimens examined: Bahama Islands: Nassau, New
Providence Island (GT W).—Florida: Biscayne Bay
(MCZ); Virginia Key; Old Spanish Light, Biscayne Bay
(both GTW); Soldier Key (RCB); Ragged Keys (GTW,
MCZ); Elliott Key (MCZ); Just E of Card Sound Bridge,
Key Largo (RCB); Tavenier Key; Windley Key (both
GTW); Tea Table Key; Indian Key Fill (both RCB);
Indian Key (MCZ); Long Key, bay side (RCB); Conch
Key; Grassy Key (both GTW); just N of Crawl Key
(RCB); Crawl Key, bay side; Old Ferry Dock, Crawl
Key; Bay Point, Crawl Key (all MCZ); Bonefish Key
(GTW,MCZ); Pigeon Key (MCZ); Little Duck Key
(GTW,RCB); Missouri Key (GTW,MCZ,RCB); Bahia
Honda (GTW); West Summerland Key (RCB); Little
Torch Key (MCZ); Pelican Shoals; Sambo Shoals (both
GTW); Boca Chica (MCZ); Key West (GTW,MCZ);
Long Key Reef, Dry Tortugas; N and E side of Bush
Key, Dry Tortugas, 2-4 m; W side of Ft. Jefferson, Gar-
den Key, 1-2 m; near moat wall, W side of Garden Key,
Dry Tortugas, 0-2 m; SW corner of Garden Key, Dry
Tortugas, 1.5-2 m; Bird Key Reef, Dry Tortugas, 0.5-1
m (all FDNR); BLM Sta. 151, 28°32'6”N, 084°18'54’W,
80-90 ft (24-27 m); BLM Sta. 047, 28°34'N,
084°20'12”W, 85-95 ft (26-28 m); BLM Sta. 251.
28°32'54"N, 084°6'24”W, 80-90 ft (24-27 m); BLM Sta.
247, 28°36'18"N, 084°9'42”W, 80-90 ft (24-27 m); BLM
Sta. 146, 28°41'N, 084°23'18”W, 80-90 ft (24-27 m) (all
approximately 110 mi [176 km] S of St. Marks, all
DISL).—Honduras: Anthonys Key, Roatan Id. (RCB).—
Panama: Galeta Id. (GTW,RCB); Verde Id., Mantilla
Pt., Porto Bello (RCB).

Stenoplax producta (Reeve, 1847)

(Figures 8C, D, 9C, 14-16, 24)

Chiton productus REEVE, 1847:pl. 17, sp. 97 (Locality un-
known [herein designated to be Eight Mile Rock, Grand
Bahama Island]; holotype in BMNH).

The Veliger, Vol. 27, No. 3

Ischnochiton (Stenoplax) limaciformis (Sowerby). BOONE, 1933:
199, pl. 125, fig. A. Non Stenoplax limaciformis (Sow-
erby).

Stenoplax limaciformis (Sowerby). LYONS, 1981:38 (list). Non
Stenoplax limaciformis (Sowerby).

Non Chiton productus ‘Reeve’ THIELE, 1909:7; 1910a:80;
1910b:110 [=Stenoplax purpurascens (C. B. Adams)].

Description: Animal reaching a length of about 30 mm,
elongate. Color variable but usually speckled with green
and white; slight rusty tinge often seen. Anterior valve
usually granular; granules radially or concentrically ar-
ranged, depending on growth lines; insertion plate with
8-12 slits. Intermediate valves with fine longitudinal ribs
on broad jugum; central areas with slightly flattened lon-
gitudinal ribs that are directed laterally; ribs almost as
wide or wider than intervening grooves; ribs become ir-
regular, but rarely break into a few pustules near lateral
triangle; lateral triangle often sharply raised, with con-
centric ribs directed along antero-posterior axis; insertion
plate with one slit per side. Grooves of lateral triangle and
central areas with very fine furrowlike riblets visible at
high magnification. Posterior valve elongate, mucro pos-
teriorly acentric; jugal and central areas as in intermediate
valves; posterior slope as in anterior valve, insertion plate
with 8-11 slits.

Girdle scales about 118 um high, 76-97 wm wide; 12-
18 ribs per scale; ribs do not reach apex. Girdle fringe
with straight, narrow spicules about 126 wm long, 14 wm
wide.

Radula typical for subgenus. Denticle cap of major lat-
eral tooth tricuspidate, rather elongate, small cusp some-
what reduced to nearly absent; two large cusps prominent,
blunt; brown basal spot absent; elongate, V-shaped “‘tear”’
often present at base (Figures 8C, D).

Remarks: Stenoplax producta has remained unrecognized
since its introduction by REEVE (1847). Although the lo-
cality of this species was unknown, most authors have
listed the name in synonymy with S. limaciformis (Sow-
erby, 1832). After examination of the figures presented
by Reeve, especially the “detail of sculpture” figure at the
back of his work, and color and black-and-white photo-
graphs I made of the unique type specimen present in the
British Museum (Natural History), I have concluded that
Reeve’s species is the Caribbean Stenoplax that one finds
so commonly in the Bahama Islands. I herein designate
Eight Mile Rock, Grand Bahama Island, as the type lo-
cality of S. producta. The type specimen exhibits concen-
tric ribs on the lateral triangle that are directed along the
longitudinal axis and not directed slightly obliquely as one
sees in S. purpurascens, and the elongate posterior valve
has a posteriorly acentric mucro. REEVE (1847:Chiton pl.
17, sp. 97) also seemed aware of the narrow ribs of his
new species: he noted that the central areas were “longi-
tudinally grooved”’ [stress on grooves]; in the next species
listed, Chiton sanguineus [=S. purpurascens], he stated that
the central areas were “very closely longitudinally striat-
ed’? [stress on ribs]. All of these features lead one to rec-
ognize S. producta as the “Bahamian” Stenoplax.

R. C. Bullock, 1985

REEVE’s (1847) statements and illustrations do not com-
pletely agree with the British Museum specimen. Reeve
clearly figures concentric ribs on the posterior slope of the
posterior valve, and in the description he stated “terminal
valves and lateral areas of the rest concentrically undu-
lately striated.” Although this statement is true for lateral
triangle sculpture, the posterior slope of the single type
specimen has a rather granular appearance due to a com-
bination of radial and concentric arrangement of the gran-
ules. Whether Reeve for brevity’s sake stressed ‘“‘concen-
tric,” or whether the specimen Reeve described is no longer
present in the type lot, is uncertain. Although Stenoplax
producta typically has very granular areas on the anterior
and posterior valves, it also can have wavy concentric ribs,
as the specimens from Gold Rock, Grand Bahama Island
attest (FDNR 30416).

There seems to be no doubt that Stenoplax producta is
more closely related to S. floridana than to S. limaciformis
or S. purpurascens. The denticle cap of the major lateral
tooth of S. producta most closely resembles that of S. flor-
idana and both types lack the brown basal spot observed
on the denticle caps of S. limaciformis and S. purpurascens
(Figure 8). Both S. producta and S. floridana have consid-
erably fewer esthete pores, and a higher percentage of the
valve surface is taken up by ribs, although in this respect
S. producta is much more similar to S. limaciformis and S.
purpurascens than to §. floridana (Table 1). Canonical
variate analysis using the density of megalopores (LDEN)
and percent rib area (PCTRA) indicates that S. producta
forms a natural group with S. floridana; the Mahalanobis
D? distance value is low when S. producta and S. floridana
are compared, and high when S. producta is contrasted
with the other two species (Table 2).

Distribution: Stenoplax producta ranges from the Bahama
Islands and the offshore reef areas of the Florida Keys
south to Cuba, Hispaniola, Jamaica, Honduras, and Isla
de San Andrés (Figure 9C).

Specimens examined: Florida: Ragged Rocks (GTW);
Looe Key (MCZ); Pelican Shoals (GTW); Sand Key, S
of Key West, 0.5-2 m; Long Key Reef, Dry Tortugas;
patch reef near Long Key Reef, Dry Tortugas, 1.5-2.5
m; N and E side of Bush Key, Dry Tortugas, 2-4 m; W
side of Ft. Jefferson, Garden Key, Dry Tortugas, 1-2 m;
SW corner of Garden Key, Dry Tortugas, 1.5-2 m; near
moat wall, W side of Garden Key, Dry Tortugas, 0-2 m;
Bird Key Reef, Dry Tortugas, 0.5-1 m; W side of Log-
gerhead Key, Dry Tortugas, 0-1 m (all FDNR).—Ba-
hama Islands: Grand Bahama Island: Settlement Point, West
End, 0-2 m; Sports Dock, West End, 0.5-1.5 m (both
FDNR); shallow cove, 2 mi (3.2 km) W of Eight Mile
Rock, 0-0.5 m; Eight Mile Rock, 1-2 m (both RCB);
pool at entrance to underwater cave, E of Eight Mile
Rock, 0.5-1 m (FDNR,RCB); W side of jetty, W of en-
trance to Freeport Harbour, 2-3 m (RCB); Jetty and
adjacent bar, Caravel Beach, Freeport, 0-1.5 m; Gold
Rock, 18 m; Deadman’s Reef, 0.5-1.5 m; McLean’s Town,
East End, 1-2 m (all FDNR); Bimini Islands: Bimini

Page 305

(GTW); North Lagoon, E coast of North Bimini
(FMNH); Gun Cay, Bimini (MCZ); Eleuthera Island:
Harbour Id. (GTW); Sand Pt., Savanna Sound (MCZ);
New Providence Island: Nassau (GTW); Eastern Point;
Fox Hill, South Beach (both MCZ); E of Clifton Pier,
1-2 m; Clifton Bluff, 4 m; Clifton Pt., 0-2 m (all RCB);
Cat Island: Arthur’s Town (MCZ); Long Island: Clarence
Town (MCZ).—Cuba: Varadero (GTW).—Jamaica: 2 mi
(3.2 km) W of Runaway Bay, 1-1.5 m; along seawall,
just W of Runaway Bay, 0.5-1 m (both RCB).—Haitz:
Gonave Id.; Miragoane (both MCZ).—Dominican Re-
public: Isla La Matica, Playa Boca Chica, 0.5-1 m
(RCB).—Isla de San Andrés: Paradise Pt. (RCB).—Hon-
duras: Anthonys Key, Roatan (RCB).

DISCUSSION

According to Mayr (1969:411), sibling species are “pairs
or groups of closely related species which are reproduc-
tively isolated but morphologically identical or nearly so.”
The different species of the Stenoplax limaciformis complex
are certainly very similar in appearance and the question
that then remains is the determination of reproductive
isolation. If the Caribbean species were geographically
present as entirely allopatric groups of populations, which
they are not, it might be convenient for some taxonomists,
given the lack of major morphological differences, to as-
sume that reproductive isolation had not been achieved
and to view them as subspecies. But as WILEY (1981)
noted, this approach, which is based on the view that
species status has not been tested by sympatry, would lead
to confusion. In the present paper it is shown that over
part of its range each Caribbean species occurs sympatri-
cally with another member of the group. Stenoplax pur-
purascens occurs with S. producta in Cuba, Hispaniola,
and Jamaica; it is found with S. florrdana in Panama and
Colombia. Stenoplax floridana lives with S. producta on the
offshore reefs of the Florida Keys and Roatan Island,
Honduras. The fact that no hybrid zones are evident where
sympatry occurs is conclusive proof that speciation has
occurred. The allopatric S. limaciformis from the eastern
Pacific must be considered specifically distinct from Ca-
ribbean members. It is as different from Caribbean mem-
bers as the Caribbean members are from each other. It
must be stressed that the small, but consistent, morpho-
logical differences observed among members of the Steno-
plax limaciformis species complex strongly support the ar-
gument that species status has been achieved in each case.

The lack of biological information about Stenoplax s.s.,
and chitons in general, prohibits any definitive statements
about the restricted distribution of these species within the
West Indian faunal province. The distributional pattern
of members of the S. limaciformis complex in the West
Indies, however, does suggest that their larvae remain
planktonic for only a brief period. If this were not so one
would expect broader distributional patterns within the
West Indian province. The only report in the literature
pertaining to the embryogeny of Stenoplax is that of HEATH

Page 306

The Veliger, Vol. 27, No. 3

(1899) who reported that in Stenoplax (Stenoradsia) heath-
iana Berry, 1946, settlement of the larvae occurs during a
period of 15 minutes to three hours after they become free
swimming. A relatively short, but not as brief, planktonic
existence is found in various other polyplacophorans
(PEARSE, 1979). Stenoplax purpurascens occurs throughout
the West Indies, yet it is conspicuously absent in the Ba-
hama Islands and the Florida Keys. Its erroneously re-
ported presence in Bermuda (CROZIER, 1920; ABBOTT,
1974) is based on specimens of Stenoplax boog: (Haddon,
1886). Stenoplax floridana, so abundant in the Florida Keys,
is apparently lacking in the Bahama Islands, and S. pro-
ducta, which is widely distributed in the western Carib-
bean, is commonly found at Dry Tortugas and offshore
reefs of the Florida Keys, but not in the lower Florida
Keys proper. It is likely that the Gulf Stream is a major
disrupting force in the distribution of Stenoplax, not count-
ing the fact that the distances involved, such as between
Florida and the Bahama Islands, might be a sufficiently
great barrier even if current patterns were more favorable.

Given the restricted distribution of Stenoplax s.s. within
the West Indian faunal province, it would seem that the
species might provide additional evidence for the theory
of paraprovincialism as applied to the Caribbean (PETUCH,
1982). Stenoplax floridana and S. producta have a distri-
butional pattern that reflects a Caloosahatchian origin,
while the range of S. purpurascens indicates a Gatunian
origin. The general current pattern in the Caribbean,
which is from east to west, has probably kept Stenoplax
species from extending their range eastward except for
along continental margins; but even along continental
shores large regions of mangrove and muddy substrates
could prove to be an effective barrier. Thus, S$. floridana
and S. producta have probably been restricted to the west-
ern Caribbean and only S. purpurascens exists in the Less-
er Antilles. Stenoplax limaciformis is the only species of
the S. limaciformis group that is found in the eastern Pa-
cific due to the continuous continental margin and the lack
of insular environments. Shell and radular morphology of
S. limaciformis are quite uniform throughout its extended
range. It is lacking in offshore island groups, such as the
Revillagigedo Archipelago (FERREIRA, 1983), Cocos Is-
land (HERTLEIN, 1963), and the Galapagos Islands (SMITH
& FERREIRA, 1977), which possess a fairly typical Pan-
amic fauna.

Specific comments on the evolutionary relationships
among the species of New World Stenoplax s.s. must await
additional material. Adequate samples from the western
Caribbean are especially lacking, but evidence available
to date indicates that the S. limaciformis complex is com-
posed of two distinct groups. The first group, whose mem-
bers include S. floridana and S. producta, forms a lineage
characterized by reduced rib width, fewer esthetes, and
an elongate denticle cap. The second group, which in-
cludes S. purpurascens and S. limaciformis, has wide ribs,
many esthete pores, and a rather squat denticle cap. These
conclusions have been drawn from general observations of
shell and radular morphology. The results of SEM anal-

ysis of valve microsculpture, especially the extent of rib
surface area and the density of megalesthete pores, have
provided corroborating evidence.

ACKNOWLEDGMENTS

For the opportunity to examine museum collections I am
grateful to: K. J. Boss and R. D. Turner, Museum of
Comparative Zoology, Harvard University; J. D. Taylor,
J. Peake, and K. Way, British Museum (Natural His-
tory); W. G. Lyons, Florida Department of Natural Re-
sources Marine Research Laboratory, St. Petersburg; and
T. Hopkins and D. Blizzard, Dauphin Island Sea Lab,
Alabama. Additional Stenoplax specimens were kindly
provided by C. Birkeland, J. Brooks, D. Dexter, D. Holt,
A. Martins, T. Spight, and G. T. Watters. Preliminary
work on Stenoplax radulae was done by R. Burt. A trans-
lation of the description of Ischnochiton kempfi was given
me by A. Martins. P. V. August generously assisted with
the analysis of the SEM data. The excellent line drawings
were done by D. DeCarlo. Computer facilities were pro-
vided by the Academic Computer Center of the University
of Rhode Island. The manuscript benefitted by the con-
structive comments of three anonymous reviewers.

Financial support for fieldwork in the Florida Keys and
the West Indies was provided by the University of Rhode
Island Foundation, the University Research Committee,
the Department of Zoology, the Office of the Vice Presi-
dent for Academic Affairs, and the Lerner Gray Fund for
Marine Research.

LITERATURE CITED

ABBOTT, R. T. 1954. American seashells. D. Van Nostrand
Co.: New York. 541 pp.

AsBBoTT, R. T. 1958. The marine mollusks of Grand Cayman
Island, British West Indies. Monogr. Acad. Natur. Sci.,
Philadelphia, No. 11:138 pp.

ABBOTT, R. T. 1974. American seashells. 2nd edition. Van
Nostrand Reinhold Co.: New York. 663 pp.

ADAMS, C. B. 1845. Specierum novarum conchyliorum, in Ja-
maica repertorum, synopsis. Proc. Boston Soc. Natur. Hist.
2:1-17.

AsHBy, E. 1918. Monograph of the genus Stenochiton (Order
Polyplacophora), with descriptions of two new species. Trans.
Roy. Soc. So. Australia 42:65-78.

BARNAWELL, E: B. 1960. The carnivorous habit among the
Polyplacophora. Veliger 2:85-88.

BoongE, L. 1933. Scientific results of the cruises of the yachts
“Eagle” and “Ara,” 1921-1928. William K. Vanderbilt,
commanding. Bull. Vanderbilt Marine Mus. 4:165-210, pls.
103-133.

Boss, K. J., J. ROSEWATER & F. A. RUHOFF. 1968. The zoo-
logical taxa of William Healey Dall. Bull. U.S. Natl. Mus.
287:427 pp.

BRoperIP, W. J. & G. B. SoweRBy. 1832-1833. Characters
of new species of Mollusca and Conchifera collected by Mr.
Cuming. Proc. Comm. Sci. Corresp. Zool. Soc. London for
1832:25-33, 50-61, 104-108, 113-120, 124-216 (all 1832);
173-179, 194-202 (both 1833).

CAMPBELL, N. A. & W. R. ATCHLEY. 1981. The geometry of
canonical variate analysis. Syst. Zool. 30:268-280.

CLENCH, W. J. & R. D. TURNER. 1950. The western Atlantic

R. C. Bullock, 1985

marine mollusks described by C. B. Adams. Occasional Pa-
pers on Mollusks, Harvard, 1:233-403, pls. 29-49.

CLEsSIN, S. 1903-1904. Die Familie Chitonidae. Jn: Martini
& Chemnitz, Syst. Conch.-Cab. 6(4):pls. 1-3 (1843); pls.
4-15 (1902); pp. 1-96, pls. 16-39 (1903); pp. 97-135, pls.
40, 41 (1904).

Crozier, W. J. 1920. Note on the photic sensitivity of the
chitons. Amer. Natur. 54:376-380.

DALL, W. H. 1879. Report on the limpets and chitons of the
Alaskan and Arctic regions, with descriptions of the genera
and species believed to be new. Proc. U.S. Natl. Mus. 1:
281-344 [Sci. Results Expl. Alaska, art. 4, pp. 63-126].

Da.L, W. H. 1889. Reports on the results of dredging, under
the supervision of Alexander Agassiz, in the Gulf of Mexico
(1877-78) and in the Caribbean Sea (1879-80), by the U. S.
Coast Survey Steamer “Blake,” Lieut.-Commander C. D.
Sigsbee, U.S.N., and Commander J. R. Bartlett, U.S.N.,
commanding. XXIX. Report on the Mollusca. Part II. Gas-
tropoda and Scaphopoda. Bull. Mus. Comp. Zool. (Har-
vard) 18:1-492, pls. 10-40.

DALL, W. H. & C. T. Stimpson. 1901. The Mollusca of Porto
Rico. U.S. Fish Comm. Bull. for 1900 1:351-524, pls. 53-
58.

EMERSON, W. K. & M. K. JAcoBson. 1976. The American
Museum of Natural History guide to shells. Alfred A. Knopf:
New York. 482 pp.

FERREIRA, A. J. 1978. The chiton species described by C. B.
Adams, 1845, from Jamaica. Bull. Mar. Sci. 28:81-91.
FERREIRA, A. J. 1983. The chiton fauna of the Revillagigedo

Archipelago, Mexico. Veliger 25:307-322.

GOTTING, K.-J. 1973. Die Polyplacophora der karibischen
Kiiste Kolumbiens. Archiv fiir Molluskenkunde 103:243-
261.

HeaTH, H. 1899. The development of IJschnochiton. Zool.
Jahrb., Abt. Anat. Ontog. Thiere 12:567-656.

HERTLEIN, L. G. 1963. Contribution to the biogeography of
Cocos Island, including a bibliography. Proc. Calif. Acad.
Sci., 4th ser., 32(8):219-289.

Humrrey, M. 1975. Sea shells of the West Indies. Taplinger
Publ. Co.: New York. 351 pp.

HyMan, L. H. 1967. The invertebrates, Volume VI, Mollusca
I. McGraw-Hill: New York. 792 pp.

IREDALE, T. & A. F. B. Hutt. 1927. A monograph of the
Australian loricates. Roy. Zool. Soc. New South Wales
(Sydney) 168 pp.

JOHNSON, C. W. 1934. List of marine Mollusca of the Atlantic
coast from Labrador to Texas. Proc. Boston Soc. Natur.
Hist. 40(1):1-204.

Kaas, P. 1972. Polyplacophora of the Caribbean region. Stud-
ies on the Fauna of Curacao and other Caribbean Islands
41 (137):162 pp., 9 pls.

Kaas, P. & R. A. VAN BELLE. 1980. Catalogue of living chi-
tons (Mollusca: Polyplacophora). W. Backhuys: Rotterdam.
144 pp.

KEEN, A. M. 1958. Sea shells of tropical west America. Stan-
ford Univ. Press: Stanford, California. 619 pp.

KEEN, A. M. 1971. Sea shells of tropical west America. 2nd
edition. Stanford Univ. Press: Stanford, California. 1064 pp.
[Polyplacophora section by S. Thorpe].

Lyons, W. G. 1981. Comments on chitons (Mollusca: Poly-
placophora) of the Bahama Islands. Bull. Amer. Malacol.
Union for 1981:38-39.

Mayr, E. 1969. Principles of systematic zoology. McGraw-
Hill: New York. 428 pp.

Page 307

MCLEAN, J. 1962. Feeding behaviour of the chiton Placipho-
rella. Proc. Malacol. Soc. Lond. 35:23-26.

Nerr, N. A. & L. F. Marcus. 1980. A survey of multivariate
methods for systematics. Privately published: New York.

PEARSE, J. S. 1979. Polyplacophora. Jn: A. C. Giese & J. S.
Pearse (eds.), Reproduction of marine invertebrates 5:27-
85.

Petucu, E. J. 1982. Paraprovincialism: remnants of paleo-
provincial boundaries in Recent marine molluscan prov-
inces. Proc. Biol. Soc. Wash. 95:774-780.

Pitspry, H. A. 1892-1894. Polyplacophora. Manual of Con-
chology 14:1-128 (1892); 129-350 (1893); 15:1-133 (1894).

Piutspry, H. A. & H. N. Lowe. 1932. West Mexican and
Central American mollusks collected by H. N. Lowe, 1928-
31. Proc. Acad. Natur. Sci. Philadelphia 84:33-144.

PiaTe, L. H. 1901. Die Anatomie und Phylogenie der Chi-
tonen. Zoologische Jahrbticher, Suppl. 5 [Fauna Chilensis
2]:281-592, pls. 12-16.

RAEIHLE, D. 1967. Notes on captive Leucozonia nassa Gmelin,
Chaetopleura apiculata Say, and Ischnochiton floridanus Pils-
bry. Ann. Rept. Amer. Malacol. Union for 1967:13-14.

REEVE, L. 1847. Monograph of the genus Chiton. Conchologia
Iconica 4:33 pls.

Ricul, G. 1971. Moluscos poliplacoforos do Brasil. Papéis
Avulsos de Zoologia (Sao Paulo) 24:123-146.

Rios, E. C. 1975. Brazilian marine mollusks iconography.
Fundacao Universidade do Rio Grande, Centro de Ciéncias
do Mar, Museu Oceanografico, Rio Grande, Brazil. 331
PP.

ROCHEBRUNE, A. T. DE. 1884. Diagnoses d’espéces nouvelles
de la famille des Chitonidae (deuxiéme supplément). Bull.
Soc. Philom. Paris 8(7):32-39.

SHUTTLEWORTH, R. J. 1853. Uber den Bau der Chitoniden,
mit Aufzadhlung der die Antillen und die Canarischen Inseln
bewohnenden Arten. Mittheil. naturforsch. Gesellschaft Bern
1853:169-207 [reprinted in Diagnosen neuer Mollusken,
no. 4:45-83].

SMITH, A. G. 1960. Amphineura. Pp. 41-76. In: R. C. Moore
(ed.), Treatise on invertebrate paleontology, Part I, Mol-
lusca 1.

SmiTH, A. G. & A. J. FERREIRA. 1977. Chiton fauna of the
Galapagos Islands. Veliger 20:82-97.

Taki, Is. 1954. Fauna of chitons around Japanese islands.
Stenoplax of Japan. Bull. Natur. Sci. Mus., Tokyo (n:s.)
1(2):72-78, pls. 20-23.

THIELE, J. 1893. Polyplacophoren. Jn: F. H. Troschel, Das
Gebiss der Schnecken 2:353-401, pls. 30-32.

THIELE, J. 1909-1910a. Revision des Systems der Chitonen.
Zoologica 22:1-58, pls. 1-6 (1909); 71-132, pls. 7-10 (1910).

THIELE, J. 1910b. Molluskenfauna Westindiens. Zoologische
Jahrbticher, Suppl. 11:109-132, pl. 9.

TurGEon, D. D. & W. G. Lyons. 1977. A tropical marine
molluscan assemblage in the northeastern Gulf of Mexico.
Bull. Amer. Malacol. Union for 1977:88-89.

VAN BELLE, R. A. 1977. Sur la classification des Polyplaco-
phora: III. Classification systématique des Subterenochiton-
idae et des Ischnochitonidae (Neoloricata: Chitonina). In-
formations de la Société Belge de Malacologie, ser. 5, no. 2,
pp. 15-39, pls. 4, 5. :

WarRMKE, G. L. & R. T. ABBoTT. 1961. Caribbean seashells.
Livingston Publ. Co.: Narberth, Pennsylvania. 346 pp.
WIey, E. O. 1981. Phylogenetics, the theory and practice of
phylogenetic systematics. John Wiley & Sons: New York.

439 pp.

The Veliger 27(3):308-311 (January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

A Comparison of ‘Two Florida Populations of the

Coquina Clam, Donax variabilis Say, 1822
(Bivalvia: Donacidae). II. Growth Rates

PAUL S. MIKKELSEN

Harbor Branch Foundation, Inc., R.R. 1, Box 196, Fort Pierce, Florida 33450

Abstract. Average summer growth rates of 3.0 mm and 3.7 mm per month were obtained for samples
of Donax variabilis from southwest Florida and central eastern Florida, respectively, using length-
frequency graphs. Individuals usually live only one year.

INTRODUCTION

PREVIOUS STUDIES ON the growth of Donax variabilis, the
coquina clam, were done in Texas (LOESCH, 1957) and
North Carolina (PEARSE et al., 1942). However, these
studies were conducted prior to the designation of a new
species, Donax dorotheae Morrison, 1971, which occurs
from northwest Florida to northeast Texas. In addition,
many of the “young” of D. variabilis from the eastern
United States now in the collections of the Smithsonian
Institution and the Academy of Natural Sciences were
determined to be Donax parvula Philippi, 1849 (see
Morrison, 1971), indicating identification problems in
the past. MORRISON (1971) also split D. variabilis (as D.
roemert Philippi, 1849) into western (western Gulf of
Mexico) and eastern (eastern Gulf of Mexico and eastern
United States) subspecific forms. MARSH (1962) exam-
ined length-frequency graphs of D. variabilis collected
during the summer and early fall from Pawleys Island,
South Carolina, but found no well-defined size classes.
Therefore, the growth rates of the eastern and western
forms of D. variabilis possibly remain undetermined. In
this paper, summer growth rates of Donax variabilis are
given from two Florida populations, along with estimates
of spawning periods and lifespan.

MATERIALS anpD METHODS

Specimens of Donax variabilis were collected monthly (pri-
marily for analysis of coloration and population density)
from April through September 1976. Specimens were
gathered from eight transects perpendicular to the beach,
each consisting of about eight 15-cm diameter cores spaced
at 1-m intervals within the intertidal zone of exposed sandy

beaches on the central eastern (Indialantic) and south-
western (Sanibel Island) coasts of Florida. Samples were
sieved using a 1.2-mm mesh. The number of monthly
cores varied due to the varying width of the swash zone
being sampled at the time; the number of monthly cores
averaged 40 at Sanibel and 49 at Indialantic Beach. Half
of the transects were at 25-m intervals and half at 5-m
intervals to decrease the possibility of missing localized
aggregations of animals. Donax parvula was collected along
with D. variabilis at the Indialantic site, but specimens of
the former were separated and not analyzed for this study.
Other information concerning sampling locations, meth-
ods, and times have been given previously (MIKKELSEN,
1981). Shell lengths were measured with calipers to +0.1
mm. The large samples of shells from Sanibel (excluding
the April sample) were subsampled using a geological
sediment sample splitter; all specimens from Indialantic
were measured. Groupings to determine “‘sets” of individ-
uals on length-frequency graphs were determined accord-
ing to CassIgE (1954).

RESULTS

At Indialantic Beach, 477 specimens of Donax variabilis
were collected and analyzed. One portion of the year class
had somewhat regular monthly growth increments from
May through August (crosshatched area, Figure 1). The
mean shell length of these individuals increased from 7
mm in May to 18 mm in August, an increase of 11 mm
over a period of 3 months, or an average summer growth
rate of about 7.3 mm per month. Another set of young
occurred, averaging 9 mm in length in the third week of
September (stippled area, Figure 1).

Page 309

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number of specimens). First set (crosshatched);

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Length-frequency graphs of Donax variabilis from Sanibel (N

second set (stippled).

Page 310

At Sanibel, because 28,832 specimens were collected,
subsamples provided manageable numbers, yielding
monthly subsamples consisting of about 500 specimens
each. The size classes could be followed from May through
July (crosshatched area, Figure 2). The means of the dis-
tributions pass from 5 to 11 mm over a period of 2 months
(May to July) and from 6 to 9 mm over 1 month (August
to September), indicating an average summer growth rate
of 3.0 mm per month. The Sanibel Island population also
showed a second set of young (stippled area, Figure 2)
around the first week of June; these had subsequently
grown to a mean size of 6 mm by August and to 9 mm
in September.

DISCUSSION

Constant movement of beach sands and contained clams,
as well as the migratory ability of Donax variabilis, pre-
vented use of a “mark-and-recapture” technique of growth
measurement. Thus, repeated sampling of the population
to construct length-frequency graphs was used, although
problems exist with its use.

LoEScCH (1957) in a study of two species of Donax
pointed out that length-frequency curves can indicate
growth only if (1) the mortality rate is the same for all
sizes of individuals, (2) the clams enter the population as
an entire group, and (3) there is no drift of specimens
along the beach. In addition, permanent or temporary
removal of individuals by wave action may wash speci-
mens into the subtidal region (MIKKELSEN, 1981). Also,
predators may selectively remove a particular size of clam.
Many of the predators listed by LOESCH (1957) were con-
firmed during the present study, and to that list is added
the Sheepshead fish, Archosargus probatocephalus (Wal-
baum, 1792); LEBER (1982a, b) added others. Selective
removal by each of these predators seems likely and prob-
ably varied monthly depending upon the type, abundance,
and size of the predators. This selectivity could have con-
tributed to the skewing of the length-frequency data (Fig-
ures 1, 2), seemingly altering regular monthly growth in-
crements present in individuals. Thus, growth alone may
not be the reason for the position and rate of advancement
of the modes and means present in the length-frequency
graphs.

An additional factor is that the monitored population
must consist of a single species. Approximately 54% of the
Donax collected at Indialantic Beach were D. parvula and
were not analyzed for this study. In his analysis of growth
rate of D. variabilis from the Texas coast, LOESCH (1957)
may have inadvertently included specimens of D. dorotheae
and/or D. texasiana, similar but shorter and more obese
species, whose ranges overlap that of D. variabilis in the
western Gulf of Mexico. This factor could have influenced
Loesch’s lower growth rates of 1.75, 0.67 and 0.33 mm
per month in his populations from three separate stations.
However, this extreme variation may be real, and growth
rates determined in the present study may be high because
they are merely summer growth rates, rather than an

The Veliger, Vola277-eNows

average over the year. Sanibel Island presented no iden-
tification difficulties because D. variabilis was the only
donacid that occurred there.

Assuming a constant growth rate, the occurrence of nu-
merous individuals in the May sample at Indialantic Beach
whose lengths were clustered around 7 mm indicates a
settlement approximately 7.5 weeks prior to that time, or
about the first to second week of March. Thus, with a
larval stage of 3 weeks average duration (CHANLEY, 1969),
spawning may have been centered around the third week
in February. The second group of young at Indialantic
(averaging 9 mm in the third week of September) indicates
a second spawning occurred on the east coast about 13
weeks earlier, or about the second week of June.

Following the same assumptions at Sanibel, settlement
may have occurred, at 275 to 340 wm (CHANLEY, 1969),
around the second week of March, with spawning cen-
tered around the third week of February. This is essen-
tially identical to the first spawning that occurred at In-
dialantic Beach. The second group of young at Sanibel
indicated that a second spawning probably occurred about
the second week of May and settlement about the first
week of June. This second spawning at Sanibel was about
4 weeks earlier than the second spawning and settlement
at Indialantic Beach.

Although spawning dates were extrapolated from length-
frequency graphs, they may be reasonable estimates.
Causes of error would include a more rapid growth rate
for individuals younger than those examined. Correction
for this error would yield spawning dates somewhat later
in time. The dates reported herein differ, however, from
those given for the North Carolina populations that were
reported to have planktonic larvae from summer to fall
(WILLIAMS & PORTER, 1971). LEBER (1982a) observed
settlement of Donax variabilis in North Carolina during
February and November.

The general absence of an abundance of large Donax
variabilis throughout the summer months indicates that
most of those specimens that had matured the previous
fall and winter had probably died, although some may
have moved and remained offshore. This suggests that the
majority of individuals probably live for approximately 1
year, with a few entering a second year. This is consistent
with the findings of LoEscH (1957) and PEARSE et al.
(1942) who also used length-frequency graphs. MARSH
(1962) also noted fall declines in the intertidal density of
D. variabilis. Although LEBER (1982a, b) attributed fall
declines in the number of Donax variabilis to emigration
to subtidal levels, LEBER (1982a, fig. 3) also noted only a
few large specimens entering a second year (at least in-
tertidally). However, MORRISON (1971), who compiled
data by measuring museum specimens, determined a 2-yr
life span.

ACKNOWLEDGMENTS

I thank Drs. Robert H. Gore, Robert W. Virnstein, and
Kerry B. Clark for reviewing early drafts of the manu-

-P. S. Mikkelsen, 1985

script. My gratitude is also due to Sally Hatton, Edward
Kobovitz, Alan Siegel, and Debbie Wells who helped with
the sampling, and especially to Paula Mikkelsen whose
assistance with all aspects of the study is most appreciated.
Contribution number 367 of the Harbor Branch Foun-
dation, Inc.

LITERATURE CITED

CassiE, R. M. 1954. Some uses of probability paper in the
analysis of size frequency distributions. Aust. J. Mar.
Freshwater Res. 5:513-522.

CHANLEY, P. 1969. Larval development of the coquina clam,
Donax variabilis Say, with a discussion of the larval hinge
in the Tellinacea. Bull. Mar. Sci. 19(1):214-224.

LEBER, K. 1982a. Bivalves (Tellinacea: Donacidae) on a North
Carolina beach: contrasting population size structures and
tidal migrations. Mar. Ecol. Prog. Ser. 7:297-301.

LEBER, K. 1982b. Seasonality of macroinvertebrates on a tem-

Page 311

perate, high wave energy sandy beach. Bull. Mar. Sci. 32(1):
86-98.

Loescn, H. C. 1957. Studies on the ecology of two species of
Donax on Mustang Island, Texas. Publ. Inst. Mar. Sci.,
Univ. Texas 4:201-227.

Marsu, G. A. 1962. Studies in the ecology of the coquina
clam (Donax variabilis). Master’s Thesis, Univ. of North
Carolina, Chapel Hill. 30 pp.

MIKKELSEN, P. S. 1981. A comparison of two Florida popu-
lations of the coquina clam, Donax variabilis Say, 1822 (Bi-
valvia: Donacidae). I. Population density, intertidal distri-
bution, and migratory behavior. Veliger 23(3):230-239.

Morrison, J. P. E. 1971. Western Atlantic Donax. Proc. Biol.
Soc. Wash. 83(48):545-568.

PearsE, A. S., H. J. HUMM & G. W. WHARTON. 1942. Ecol-
ogy of sand beaches at Beaufort, North Carolina. Ecol.
Monogr. 12:136-190.

WILLIAMS, A. B. & H. J. PoRTER. 1971. A ten-year study of
meroplankton in North Carolina estuaries: occurrence of
postmetamorphal bivalves. Chesapeake Sci. 12(1):26-32.

The Veliger 27(3):312-319 ( January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

Comparative Shell Microstructure of North American

Corbicula (Bivalvia: Sphaeriacea)

by

ROBERT S. PREZANT anp ANTONIETO TAN-TIU

Department of Biological Sciences, University of Southern Mississippi,
Hattiesburg, Mississippi 39406

Abstract.

Comparative microstructural analyses of the shells of the North American “purple” and

“white” forms of Corbicula reveal no significant differences. Shells of both forms are composed of an
outer crossed-lamellar and an inner complex crossed-lamellar microstructure. Adductor myostracum in
Corbicula is reported for the first time. The wide variation in internal shell coloration is not reflected
in shell microstructure. Internal growth bands, of possible daily origin, have been found within the

crossed-lamellar region of the valves.

INTRODUCTION

THE PROLIFIC NATURE of the exotic bivalve Corbicula sp.
in North America, and its incidental fouling characteris-
tics, has stimulated considerable efforts to understand the
biology of this organism. Most previous research has as-
sumed that a single species of Corbicula (C. fluminea) re-
sides in North America. Recently, however, HILLIS &
PATTON (1982) presented evidence that two species of
Corbicula are found sympatrically in at least some Texas
river systems. These authors based their suggestion on
electrophoretic data (allelic differences at 6 of 26 genetic
loci) and on morphometric data including internal shell
color, shell shape, and number of shell annuli. Although
the electrophoretic data are difficult to discount (and in-
deed are supported by additional fixed loci discovered by
McLEop [1984]), HILLis & PATTON (1982) concede that
“differences in number of annuli may reflect differences
in microhabitat preferences for the two forms.” In the
Brazos River, Texas (locations of Hillis and Patton’s Cor-
bicula populations), microhabitat distinctions may include
differences in water flow and siltation rates. HILLIS &
PATTON (1982) typically found a form of Corbicula with
predominantly white internal shell coloration (‘‘white”’
forms) in less energetic areas with higher siltation rates,
and forms with predominantly purple internal shell col-
oration (“‘purple” forms) in rocky areas with faster mov-
ing waters. PREZANT & CHALERMWAT (1984), by modi-
fying the clam’s environment in the laboratory, have found
that “white” forms with purple highlights may be induced
toward totally white internal shell coloration. It was also
found by the latter authors (1983) that clams maintained

at warm temperatures under specific high organic condi-
tions, as well as unhealthy or moribund animals, produced
an internal crossed acicular microstructural pattern. This
type of microstructure is significantly different from the
typical complex crossed-lamellar pattern found in non-
stressed or healthy clams of the same population. It was
suggested that this modified shell type reflected stressful
conditions, with animals devoting their energies toward
life sustaining functions and away from normal shell pro-
duction.

The taxonomic uncertainty that presently exists in North
American corbiculid systematics, in conjunction with pos-
sible ecophenotypic shell modifications produced in the
laboratory, prompted this comparative study of shell mi-
crostructure of the two forms of North American Corbic-
ula. Scanning electron microscopic studies revealed no sig-
nificant microstructural differences between shells of the
two color forms but has revealed an adductor myostracum
and some interesting observations on corbiculid shell for-
mation. In addition, very subtle differences (not statisti-
cally significant in our populations with our methodology)
in total organic content were noted in the two forms.

MATERIALS anD METHODS

Shells of both the “purple” and “white” forms of North
American Corbicula were obtained from collections made
in December 1981 from the San Gabriel River, William-
son County, Texas, U.S.A., by Dr. D. Hillis. Live “white”
forms were collected from Tallahala Creek, Perry Coun-
ty, Mississippi, U.S.A. in July 1983. Soft tissues were
removed from the Tallahala Creek specimens and all shells

R. S. Prezant & A. Tan-Tiu, 1985

were dehydrated in absolute ethanol for five days, fol-
lowed by critical point drying in a Denton DCP-1 Critical
Point Drier using liquid carbon dioxide as a transfer agent.
Some specimens were free fractured prior to critical point
drying. Specimens were mounted on aluminum stubs us-
ing silver paint, coated with a thin layer of gold in a
Polaron SEM Coating Unit E5100, and examined on an
AMR 1000A scanning electron microscope at accelerating
voltages of 30 kv. At least four specimens from each group
were examined.

Organic content of shell of each form (7.e., Texas “white”
and “purple’’) was determined by combustion of crushed
valves in groups of four (run in triplicate) or individually
(seven valves of each) for 2 h at 550°C. PALMER (1983)
determined that 2 h provided optimum time for combus-
tion of organics in shell material without significant con-
version of CaCO, to CaO. Valves were weighed to the
nearest 0.05 mg and significance tested by Student’s ¢-test
(two-tailed) at 2% significance level.

All figures, except Figure 1, are scanning electron mi-
crographs.

RESULTS
Internal Coloration

The two forms, according to HILLIs & PATTON (1982),
differ in several morphometric features including overall
proportions (ratio of length, height, thickness) and num-
ber of shell annuli. These differences, however, are often
difficult to discern (COUNTS, 1983). Of particular interest
is the difference in internal shell pigmentation. According
to HILLIs & PATTON (1982) the more elongated clams
(greater length/height ratio) with greater number of an-
nuli tend to possess an internal shell with a deep purple
pigmentation. We have found a great deal of variation in
intensity of color as well as extent of coverage. The inte-
rior of some valves is entirely purple while others have a
lighter coloration over some or all the valve interior (Fig-
ure 1). In particular, the hinge teeth retain a lighter pig-
mentation. The full range of pigmentation in the “purple”
forms runs the gamut from complete coverage of light or
dark pigmentation; deeply colored only dorsal to the pal-
lial line; deeply colored only ventral to the pallial line;
deep purple highlights only beneath the umbone; or strong
pigmentation only posterior to the posterior adductor scar.

Forms with stouter (lower length/height ratio) shells

and fewer annuli show a lighter (“‘white’’) internal shell »

coloration usually with only a light purple tinge (Figure
1). Frequently, however, deeper purple coloration is found
ventral to the pallial line. Specimens of “white” forms
collected from Tallahala Creek, Mississippi, usually show
deeper purple highlights than “‘white” forms collected in
Texas. Larger Tallahala Creek specimens often exhibited
alternating concentric bands of white and purple on the
shell interior.

Specimens collected dead (7.e., empty valves) are char-

Page 313

acterized by a dull chalky internal shell coloration as op-
posed to the lustrous finish in living, healthy animals.
Animals that die in the lab often have a lustrous, white
internal shell coloration. Differences in these various shell
forms are described elsewhere (PREZANT & CHALERM-
WAT, 1983, 1984).

Shell Microstructure

There were no significant differences in shell micro-
structure between “purple” and “white” forms from San
Gabriel River, Texas, and the ‘‘white” forms from Tal-
lahala Creek, Mississippi. All specimens possess a bilay-
ered aragonitic shell composed of an internal complex
crossed-lamellar and an outer crossed-lamellar micro-
structure. An evident pallial line indicates the transition
zone between these two microstructures.

At high magnifications the interior surface of both shell
forms ventral to the pallial line appears finely granular
(Figure 2). This reflects the internal surface features of
laths composing the crossed-lamellar region. In fracture
section the bidirectional nature of the laths in this region
is quite clear (Figure 3). Laths of this region in both color
forms approximate 0.16 um in thickness. A regular series
of fine growth bands is particularly evident in radial
fractures through the crossed-lamellar region near the valve
edge (Figure 4) in “purple” specimens collected in De-
cember in the San Gabriel River, Texas. These bands
average 9.4 wm in width with about 106 bands per mm
near the periphery of a 25-mm long clam.

The inner shell layer of both forms is conical complex
crossed-lamellar in microstructure (Figures 5, 6) (termi-
nology from CARTER, 1980). Laths of this structure in
both forms average 0.2 um thick. The surficial, internal
junction between complex crossed-lamellar and crossed-
lamellar regions occurs in the form of a gradual transition
zone over the pallial line (Figure 7). On the internal sur-
face this zone occurs as a progression of emerging complex
crossed-lamellar polygonal lath tips over smooth pallial
myostracal surface (Figures 7 to 9). Lath tips range in
width from 2.5 to 3.8 wm in both forms. The irregularity
of direction of these tips reflects the tridirectionality of
internal lamels. In fracture sections the division between
the complex crossed-lamellar layer and the crossed-la-
mellar layer is demarcated by a zone of small prisms that
often leads directly to the complex crossed-lamellar pat-
tern externally but may also grade into a blocky zone that
then leads to the complex crossed-lamellar region (Figure
10).

The surficial tips of the complex crossed-lamellar laths
often decrease in size close to the umbones in “white”
forms (Figure 11). Umbonal area laths are also less reg-
ular in their polygonal tip shapes. Their smoother, finer
surfaces may be a result of erosion.

Infrequently, the complex crossed-lamellar surface in
“purple” forms near the pallial line forms a different sur-
ficial pattern for this type of microstructure. In these cases

Page 314 The Veliger, Vol. 27, No. 3

Figure 1

Variation in internal shell color (reflected in black, white, and shades of gray) of North American Corbicula. The
two columns on left represent the “white” forms and those in the right columns the “‘purple” forms. All specimens
collected from San Gabriel River, Texas, by D. Hillis.

R. S. Prezant & A. Tan-Tiu, 1985

Page 315

the laths protrude farther from the plane of the shell, are
less angular near their tips, and are much smaller in width
(Figure 12). These laths average less than 0.5 um in width
and are extremely crowded. An apparent organic deposit
is often found covering small portions of this type of sur-
face microstructure in “‘purple” forms (Figure 13). This
organic film forms a smooth, contoured layer filling in
and “flowing” over each irregularity of this surface, and
may reflect an active growth zone.

Retuctor Scars

Internal surfaces of both the anterior and posterior ad-
ductor scars of the white and purple forms show concen-

tric lines (Figure 14), which appear “lighter” than the
surrounding area when viewed with the scanning electron
microscope. In all samples, a transition zone was observed
along the peripheral region of the adductor scars nearer
the umbone. The relatively smooth internal surfaces of
the muscle scars merge with the irregular emerging lenses
of the first order lamels of the complex crossed-lamella
(Figure 15). This marks the region where the adductor
scars are being grown over by complex crossed-lamellae.
This is analogous to the event occurring at the pallial line.
The opposing peripheral half of the adductor scars, on
the other hand, did not show distinct boundaries with the
outer crossed-lamellar layer.

Radial fractures through adductor scars of both white

Explanation of Figures 2 to 10
Figure 2. Internal surface view of crossed-lamellar microstructure ventral to the pallial line near valve edge. San
Gabriel white form. Horizontal field width = 14 um.
Figure 3. Fracture section through crossed-lamellar zone. Purple form. Horizontal field width = 13 wm.

Figure 4. Radial fracture through crossed-lamellar region near valve edge showing periodic growth bands. Direction
of growth is to the left. Purple form. P, periostracum. Horizontal field width = 940 um.

Figure 5. Radial fracture showing cone complex crossed-lamellae. Very top of micrograph shows internal surface
of this region. Merger into crossed-lamellae is revealed near bottom of micrograph. Purple form. Horizontal field
width = 67 um.

Figure 6. Radial fracture of cone complex crossed-lamellar zone. Purple form. Horizontal field width = 14 um.

Figure 7. Surficial view of the junction between complex crossed-lamellar (K) and crossed-lamellar (L) regions at
the pallial line (B). Tallahala white form. Horizontal field width = 74 um.

Figure 8. Lath surface tips of complex crossed-lamellar microstructure. Shell edge toward top of micrograph.
Tallahala white form. Horizontal field width = 32 um.

Figure 9. Complex crossed-lamellar lath tips. Shell edge toward top of micrograph. Purple form. Horizontal field
width = 16 um.

Figure 10. Fracture section showing merger between complex crossed-lamellar (K) and crossed-lamellar (L)
regions. Note blocky merger laths. Purple form. Horizontal field width = 27 um.

Explanation of Figures 11 to 19
Figure 11. Modified complex crossed-lamellar surface near umbone. San Gabriel white form. Horizontal field
width = 16 um.
Figure 12. Complex crossed-lamellar surface just dorsal to the pallial line. Purple form. Horizontal field width =
15 wm.
Figure 13. Organic deposit (O) covering surface of complex crossed-lamellar region just dorsal to the pallial line.
Purple form. Horizontal field width = 8 um.
Figure 14. Internal surface of posterior adductor scar. Tallahala white. Horizontal field width = 3.4 mm.
Figure 15. Internal surface of transition zone between complex crossed-lamella (K) and myostracum (A) of posterior
adductor scar. Purple form. Horizontal field width = 80 um.
Figure 16. Radial fracture through anterior adductor scar. Myostracum (A), crossed-lamella (L). Purple form.
Horizontal field width = 16 um.
Figure 17. Radial fracture through portion of anterior adductor scar (arrow) and complex crossed-lamella (K),
submerged myostracum (A), crossed-lamella (L). Dark line (at L) represents internal fracture between lamels of
the crossed-lamellar layer oriented in opposing directions. Purple form. Horizontal field width = 415 um.

Figure 18. Radial fracture dorsal to posterior adductor scar. Part of complex crossed-lamella (K), myostracum
(A), crossed-lamella (L). Tallahala white form. Horizontal field width = 33 um.

Figure 19. Radial fracture dorsal to anterior adductor scar. Complex crossed-lamella (K), myostracum (A), crossed-
lamella (L). Purple form. Horizontal field width = 13 wm.

Page 316 The Veliger; Vols 27 Nox

SS << Les ah

Ru Se =

R. S. Prezant & A. Tan-Tiu, 1985 Page 317

Page 318

and purple forms revealed a thin internal surface pris-
matic layer, about 1.7 um high (Figure 16), composing
the adductor scars. Submerged myostracal prisms are
embedded between the internal complex crossed-lamella
and the outer crossed-lamella extending from the transi-
tion zones toward the umbones (Figures 17 to 19).

Shell Organics

Results of organic combustions of individual valves var-
ied between 1.06 to 6.62% and between 2.32 and 2.70%
for bulk determinations. Purple forms averaged slightly
more overall organic shell content than white forms, but
both methods (7.e., bulk and individual valve determina-
tions) yield averages that are not significantly different at
the 2.0% level using a Student’s ¢-test. For bulk deter-
minations, the white valves averaged (« + 1 SD) 2.45% +
0.05 shell organics and the purple valves 2.50% + 0.19.
Individual valve determinations showed an average for the
white form of 2.49% + 1.07 and 3.30% + 1.87 for purple
forms.

DISCUSSION

While some morphometric and biochemical differences
between “purple” and “white” forms of North American
Corbicula may be significant taxonomic features to indi-
cate separation of the two forms into species (HILLIS &
PATTON, 1982; McLEoD, 1984) (although CounTs [1983]
showed statistically significant overlaps between purple
and white forms based on shell morphometry), shell mi-
crostructure cannot be added to the list. MACKIE (1978)
suggests that “habitat type and temperature do not affect
the type of crystals formed in sphaeriacean shells and that
crystal type is under genetic control.”’ The microstructural
shell differences between the two forms examined here
are subtle and likely reflect individual variations. These
variations may reflect growth stages, erosive patterns, or
modified microenvironments. The present research has re-
vealed, however, some important features of Corbicula shell
microstructure (7.e., growth bands, adductor myostracum,
etc.) and stimulates some interesting questions concerning
biomineralization.

CARTER (1979) suggested that crossed-lamellar shell
structures might yield important “signatures” for address-
ing taxonomic and phylogenetic problems among extant
and fossil bivalve mollusks. PREZANT & CHALERMWAT
(1983) have shown, however, that some complex crossed-
lamellar microstructures are plastic and may be “shaped”
by basic physiologic conditions. There is great import in
this microstructural shell flexibility and great care must
be taken when using these shell features in approaching
taxonomic problems in mollusks.

Differences in organic content between the two forms
determined with the methods used here are not statisti-
cally significant at the 2% level using a Student’s t-test.
Although the reported differences in shell organics be-

(he Veliger, Volk 275 Nox

tween white and purple forms from Texas show no sta-
tistical significance, this does not necessarily preclude the
potential biological importance reflected in the slightly
higher average organic content of purple valves. “White”
forms showed slightly less overall shell organic content
than “purple” forms; this might reflect microhabitat dif-
ferences. “Purple” forms, found in faster moving waters
(HILLIs & PATTON, 1982), may produce a thicker peri-
ostracum, or the organic difference may reflect an organic
nature of the purple pigmentation. Further studies are
needed to elucidate the significance of any organic differ-
ences.

Of interest to biomineralogists are the gradual transi-
tions noted between the two major microstructural forms
found in Corbicula shell. The growth of complex crossed-
lamellar laths apparently proceeds with small “nuclei”
being deposited as incipient laths. These are gradually
added to and form the final polygonally tipped, elongate
laths. Directed growth toward a central focus outside the
plane of the shell accounts for the conical nature of this
structure.

To our knowledge there have been no reports of inter-
nal shell growth lines in Corbicula prior to this study.
Lutz & RHOADS (1977) and GORDON & CARRIKER (1978)
have clearly shown the relationship between growth lines
in bivalves and subdaily shifts in pH, and shell dissolu-
tion. The high regularity of growth bands in Corbicula
may indicate a process of active calcareous shell deposition
alternating with growth stoppage. There is no evidence of
irregular internal shell banding patterns that would in-
dicate an active seasonal period of shell production dis-
rupted by irregular periods of shell dissolution in the Tex-
as population examined. We are presently investigating
the possibility that the growth increments are of a daily
nature.

Adductor myostracum was not observed in Corbicula
“fluminea” from Japan, C. occidens Deshayes from India,
Corbicula sp. from Lake Nyanza (TAYLOR et al., 1973)
nor C. fluminea examined by MACKIE (1978). However,
this shell layer was consistently present in samples we
examined. Furthermore, there are no significant differ-
ences in microstructure of adductor scars between “white”
and “purple” forms of Corbicula.

The arrangement of growth lines on the adductor scars
suggests that the anterior adductor is migrating antero-
ventrally, while the posterior adductor is migrating pos-
teroventrally as they grow. The mantle on the leading
edge of the adductor is responsible for the formation of
the myostracum whereas the mantle on the trailing edge
produces the covering complex crossed-lamella. Adductor
scar growth lines suggest localized areas rich in organic
material.

The phenomenal spread of Corbicula in North America
(McManHon, 1982) is sound testimony to the general
adaptiveness of this bivalve. The lack of distinguishing
microstructural features between the two North American

R. S. Prezant & A. Tan-Tiu, 1985

Page 319

forms of Corbicula may be indicative of plesiomorphic
characters that are well established, successful, and un-
altered within the family. This concurs with the basic
microstructural shell trends found at the superfamily level
by KENNEDY et al. (1969). The similarities, on the other
hand, may reflect a taxonomic basis for retaining a single
species for the two forms. The total evolutionary and taxo-
nomic status of North American Corbiculidae is yet to be
completely discerned.

ACKNOWLEDGMENTS

Many of the corbiculid valves used in this study were
graciously supplied by Dr. David M. Hillis. The manu-
script has been improved by the constructive comments of
Dr. R. McMahon, Mr. K. Chalermwat, and three anon-
ymous reviewers. Many thanks also to Ms. E. Henderson
for typing the manuscript and Ms. S. DuBois for dark-
room assistance.

LITERATURE CITED

CaRTER, J. G. 1979. Crossed lamellar signatures: potentially
useful sources of information for assessing bivalve system-
atics. Geol. Soc. Amer. Abstr. 11(7):399.

CarRTER, J. G. 1980. Guide to bivalve shell microstructures.
Pp. 645-673. In: D. C. Rhoads & R. A. Lutz (eds.), Skeletal
growth of aquatic organisms. Plenum Pub. Corp.: New York.

Counts, C. L. 1983. Bivalves in the genus Corbicula Muhlfeld
1811: systematics and zoogeography. Doctoral Thesis, Uni-
versity of Delaware. 452 pp.

Gorpon, J. & M. R. Carriker. 1978. Growth lines in a
bivalve mollusk: subdaily patterns and dissolution of the
shell. Science 202:519-521.

Hits, D. M. & J. GC. PaTTon. 1982. Morphological and
electrophoretic evidence for two species of Corbicula (Bival-
via: Corbiculidae) in North America. Amer. Midl. Natur.
108:74-80.

KENNEDY, W. J., J. D. TAYLOR & A. HALL. 1969. Environ-
mental and biological controls on bivalve shell mineralogy.
Biol. Rev. Cambridge Philo. Soc. 44:499-530.

Lutz, R. A. & D. C. RHoaps. 1977. Anaerobiosis and a
theory of growth line formation. Science 198:1222-1227.

Mackig, G. L. 1978. Shell structure in freshwater Sphaeria-
cea (Bivalvia: Heterodonta). Can. J. Zool. 56:1-6.

McLeEop, M. J. 1984. Electrophoretic variation in North
American Corbicula. Proc. Second Intl. Corbicula Symp.. In
press.

McMauon, R. F. 1982. The occurrence and spread of the
introduced Asiatic freshwater clam, Corbicula fluminea
(Miller), in North America: 1924-1982. Nautilus 96:134-
141.

PALMER, A. R. 1983. Relative cost of producing skeletal or-
ganic matrix versus calcification: evidence from marine gas-
tropods. Mar. Biol. 75:287-292.

PREZANT, R. S. & K. CHALERMWAT. 1983. Environmentally
induced changes in shell microstructure of the Asiatic clam
Corbicula. Amer. Zool. Abstr. 23(4):914.

PREZANT, R. S. & K. CHALERMWAT. 1984. Induction of color
forms in Corbicula. Amer. Malacol. Bull. Abstr. 2:87.
TAYLOR, G. J., W. J. KENNEDY & A. HALL. 1973. The shell
structure and mineralogy of the Bivalvia. II. Lucinacea-
Clavagellacea: conclusions. Bull. Brit. Mus. (Natur. Hist.)

Zool. Suppl. 3:1-125.

The Veliger 27(3):320-330 ( January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

A New Species of Sphenia (Bivalvia: Myidae)
from the Gulf of Maine

ROBERT W. HANKS'

National Marine Fisheries Service, North Atlantic Coastal Fisheries Research Center,
Laboratory for Ecology and Pathology of Marine Organisms, Oxford, Maryland 21654

DAVID B. PACKER?’

Marine Systems Laboratory, National Museum of Natural History, Rm. W-310,
Smithsonian Institution, Washington, D.C. 20560

Abstract. A new species of the genus Sphenia Turton, 1822, is described from the Gulf of Maine.
Also, a lectotype for Sphenia binghami Turton, 1822, type species for the genus, is designated. Sphenia
sincera Hanks & Packer, spec. nov., is easily distinguished from other members of the genus. It is the
first Sphenia reported from the northeast coast of the United States, and, unlike other Sphenia, S.
sincera is not found in a nestling habitat. The unique, undistorted shell of S. sincera reflects this
habitat difference. The new species remained undetected until now because it had been confused with
juveniles of the well-known Mya arenaria and M. truncata. Sphenia sincera differs from species of Mya
in the shape of the chondrophore, small adult size, short life span, and completely subtidal occurrence.
The species is found in greatest abundance at depths from 30 to 63 m. Unlike species of Mya, S. sincera
prefers soft silt-clay sediments where it may be a deposit-feeder as well as a filter-feeder. It appears to

be a major food item for bottom-feeding fish.

INTRODUCTION

THE GENUS Sphenia Turton, 1822, is one of the lesser
known taxa in the bivalve family Myidae. Small size,
nestling habit, and rarity in collections have restricted sci-
entific interest in the group to taxonomic and faunistic
studies. On the other hand, the genus Mya Linné, 1758,
owing to commercial importance, wide distribution, and
great abundance, has been studied intensively. Species of
Mya are found on parts of all coastlines of the Northern
Hemisphere; species of Sphenia have been reported from
the Atlantic and Pacific coasts of North and South Amer-
ica, from Japan and Korea, from Puerto Rico, from the

‘Current address: National Marine Fisheries Service, New
England Liaison Office, P.O. Box 425 DTS, Portland, Maine
04112.

* Reprint requests should be sent to this author.

Atlantic coast of Europe, and from the Mediterranean Sea
(HABE, 1951; WARMKE & ABBOTT, 1961; KEEN, 1971;
ODE, 1971; Rios, 1975; ROSEWATER, 1975; TEBBLE, 1976;
BERNARD, 1983). Some Sphenia are said to occur on the
South African, Indian, and Malay coasts (Lamy, 1919),
but documentation is poor. Sphenza binghami Turton, 1822,
the type species of the genus by subsequent designation of
Gray (1847), has been recorded along the shores of the
Eastern Atlantic from Morocco north to the British Isles
and into the Mediterranean (TEBBLE, 1976).

Several specimens of Sphenia were dredged from the
Sheepscot River estuary in 1956, during studies of the
benthic fauna of the midcoast region in the Gulf of Maine
(HANKS, 1961, 1964). In subsequent years, large numbers
of this small bivalve were collected from deep waters of
the estuary, from coastal regions, and from fish stomachs.
Mya arenaria Linné, 1758, is abundant in this region, and
M. truncata Linné, 1758, has been reported. Although the

R. W. Hanks & D. B. Packer, 1985

Page 321

Figure 1

Lectotype herein of Sphenia binghami Turton, 1822, USNM 171240. x4.7. A and B, outer surface of left and
right valves. C & D, inner surface of left and right valves. E, chondrophore of left valve.

two species of Mya are easily separated as adults, juvenile
Mya and any stage of Sphenia might easily be confused.
Great abundance and a few previously unidentified mu-
seum specimens indicate that this new species of Sphenia
has long been an inhabitant of the Maine coast, but it has
remained unknown because of its small size and similarity
to Mya, in combination with a habitat entirely different
from that of other Sphenia. The presence of a new species
of Sphenia in the northwestern Atlantic represents a sig-
nificant addition to the known range of the genus.

Family Myibpar Lamarck, 1809
Subfamily Spheniinae Bernard, 1983
Sphenia Turton, 1822

Type species: Sphenia bingham: TURTON, 1822:36, pl. III,
figs. 4, 5; by subsequent designation Gray, 1847:190.

To the best of our knowledge, no type specimen has
previously been identified. Turton’s original material ap-
pears to have passed to the Jeffreys collection and thence
into the U.S. National Museum of Natural History, where
specimens labeled “Mya binghami Turton, ex. mus. Tur-
ton. Jeffreys Coll. #75” (USNM 171240) were found.
The allocation to Mya can be ascribed to Jeffreys, who
did not feel that Turton was justified in erecting a new
genus (JEFFREYS, 1862-1869:vol. 3, p. 72). The specimens
found were two, separated but matched, pairs of valves,
one unseparated pair, several unmatched right valves, and

what appears to be a piece of old oyster shell bored by
Cliona in which are several minute Sphenia. Although
none of these specimens matches TURTON’s (1822) figure,
it is believed that this material was part of his original
collection. Therefore, one of the matched pairs (remaining
in USNM 171240) that was most similar to that of Tur-
ton’s original description is here designated as lectotype
(Figures 1, 2). The remainder of this material is desig-
nated as paralectotypes (USNM 679166). The designa-
tion of the lectotype parallels the action of Davis (1964)
in identifying type specimens of other Turton species,
where there is sufficient evidence that the original material
is now in the U.S. National Museum of Natural History.

TURTON’s original description (1822) was brief and
somewhat ambiguous, and it led to descriptive errors by
later authors. For example, Turton said (p. 36), ““From
the Mya it [Sphenia] differs, in having the valve which
contains the tooth smaller, and received within the op-
posite one; in being closed at the hinder extremity; and in
being furnished with a concave tooth in the larger valve,
behind which is a small denticle.” In reality, the left valve
in both Mya and Sphenia is the smaller and bears the
relatively large chondrophore. NICOL (1958) commented
on this point as follows: “A few of the related Myidae are
also inequivalve, having in all such cases larger right than
left valves.” In young Mya and undistorted Sphenia the
posterior end is closed and the two valves fit tightly to-
gether. Also, the concavity in the right valve occurs in both
genera.

Page 322

DORSAL

VY Left Valve

B
LATERAL Left Valve
ZA
val

Cc

LATERAL
Right Valve

0.5mm

Figure 2

Hinge structure of Sphenia binghami Turton, 1822, lectotype
USNM 171240. A, dorsal view of chondrophore of left valve. B,
lateral view of chondrophore of left valve. C, lateral view of
resilifer of right valve.

Turton’s description of the species Sphenia binghami
was, fortunately, accurate. FISCHER (1887) and LAmMy
(1919) correctly described the Sphenia hinge.

Although Sphenia binghami is the best known species
of the genus, most accounts deal superficially with the
shell morphology, and only two descriptions of the entire
animal have been published (FoRBES & HANLEY, 1853;
YONGE, 1951); the latter description is by far the more
complete. Accounts of other species of Sphenia consist pri-
marily of records of new species or distributions, and em-
phasize shell morphology (e.g., CARPENTER, 1864; SMITH,
1893; DALL & Simpson, 1901; etc.).

Sphenia sincera Hanks & Packer, spec. nov.
(Figures 3—5)

Description—External: Shell elongate; strongly inequi-
valve, right valve larger and more deeply cupped. Poste-
rior gape small; siphons completely withdrawable into
shell. Umbones prominent, often eroded; one-third the
length from anterior end; prosogyrate; umbo of right valve
larger than left. Anterior end inflated, generally rounded;

The Veliger, Vol. 27, No. 3

dorsal margin somewhat straighter than ventral, sloping
gradually and evenly to posterior end, which may be
slightly rounded or vertical. Color chalky white; rarely
with a narrow, dark orange-brown color along margins.
Thin, yellowish periostracum sometimes present, but gen-
erally eroded from valves, covering only paired siphons.
Surface with fine, irregular concentric growth lines. A
distinct ridge running from umbo to posteroventral angle,
more acute on left valve.

Internal: Shell smooth, dull white. Adductor scars and
pallial line usually obscure. Anterior scar long; tear shaped;
extending to, or slightly past horizontal midline of shell.
Posterior scar oval; higher than wide (width two-thirds of
height); one-half distance between umbo and posterior.
Pallial line well back from edge of shell and complete
between anterior and posterior adductor scars, joining
ventral margin of pallial sinus in an acute angle at a point
directly below posterior adductor scar. Pallial sinus small,
“U” shaped; extending anteriorly two-thirds distance be-
tween posterior and umbo; dorsal margin attached to ad-
ductor scar at a slight angle.

Hinge: Nomenclature for the myid hinge follows
BERNARD (1979a) based on FUJIE (1957) and MACNEIL
(1965) (Figure 4).

Left valve: Chondrophore narrow, strongly arched, re-
sulting in ligamental pit being directed in an oblique an-
terior angle. Ligamental pit small; anterior ridge promi-
nent, its junction with ventral or outer margin directly
opposite or posterior to umbo. Radial groove large as a
consequence of posterior ridge being directed in an oblique
posterior angle. Posterior ridge expanded and flattened,
not projecting sharply beyond outer margin; median groove
shallow and open, often represented by a median undu-
lation. Anterior buttress vestigial; posterior buttress much
reduced laterally, generally extended posteriorly. Deep pit
under umbo for tooth of right valve.

Right valve: Resilifer concave, ovate-trigonal, dominat-
ed by a projecting blunt tooth on anterior end that artic-
ulates with anterior surface of anterior ridge in left valve.
Lateral end of tooth fitting into concavity under umbo of
left valve, as in a ball and socket joint, possibly providing
movement about dorsoventral axis (see TRUEMAN, 1954).

Type locality: Mouth of the Sheepscot River, Lincoln
County, Maine (69°42’W, 43°47'N); depth 33.6 m; soft
mud, primarily silt and clay. Full description of associated
fauna and environment can be found in HANKs (1964)
and LARSEN (1979).

Holotype: U.S. National Museum of Natural History,
USNM 679164.

Dimensions of the holotype: Length 5.6 mm, height 4.0
mm, width 2.5 mm, umbo to anterior 2.2 mm, umbo to
posterior 3.4 mm, chondrophore length 1.43 mm, chon-
drophore width 0.34 mm.

Paratypes: USNM 679165. The balance of our collection
remains in our possession at the National Marine Fish-

R. W. Hanks & D. B. Packer, 1985

Page 323

Figure 3

Holotype of Sphenia sincera Hanks & Packer, spec. nov., USNM 679164. x6.3. A and B, outer surface of left
and right valves. C and D, inner surface of left and right valves. E, chondrophore of left valve.

eries Service, Oxford, Maryland 21654, and the Marine
Systems Laboratory of the Smithsonian Institution in
Washington, D.C. 20560. In addition, the following is a
list of previously unidentified material in the U.S. Na-
tional Museum of Natural History now assigned to
Sphenia sincera: 1 specimen from Casco Bay (Portland),
Maine, USNM 150763; 6 specimens from off Mt. Desert
Island, Maine, 16.5 m, USNM 173122; 7 specimens from
Bar Harbor (Mt. Desert Island), Maine, USNM 199189;
1 specimen from off Gotts Island (Mt. Desert region),
Maine, USNM 451224; 2 specimens from off Gotts Is-
land, Maine, USNM 451230; 75+ specimens from
Frenchman Bay, Maine, USNM 451334; 1 specimen from
Winter Harbor (Mt. Desert region), Maine, USNM
451368; 4 specimens from Frenchman Bay, Maine,
USNM 462652.

Total number of specimens collected was about 977, of
which about 350 have been closely examined. The average
length of 70 Sphenia sincera shells, collected in June of
1962, was 5.4 mm, with a range of 3.4 to 8.9 mm. The
average height of these shells was 3.6 mm, with a range
of 2.4 to 5.3 mm. The largest shell collected from the
Sheepscot region was 9.9 mm in length.

Etymology: The specific epithet sincera, derived from the
Latin sncerus, which is defined as “‘clean, natural, without

>

mutilation,” refers to the undistorted shape of the valves,
a feature rarely found in the genus Sphenza, as well as to
their clean, brilliant whiteness.

Distribution: Known populations of Sphenia sincera are
centered around the mid-coast region of Maine, near
Boothbay Harbor and the mouth of the Sheepscot River
in the south and Gouldsboro Bay in the north. It is likely
that S. sencera has a continuous distribution from about
Casco Bay in the south (sandy sediments become promi-
nent farther southward), to perhaps the coast of Nova
Scotia in the North (Figure 6).

Comparisons: Nearly all previous records, with the ex-
ception of those for Sphenza antillensis Dall & Simpson,
1901 (DALL & Simpson, 1901; WARMKE & ABBOTT, 1961;
Rios, 1975), have reported species of Sphenia to be nes-
tlers living in the burrows constructed by other inverte-
brates. On the coast of England, S$. binghami is frequently
found living in the vacant burrows of Hratella (YONGE,
1951). Every account of European S. binghami emphasizes
the shell distortion caused by conformity to crevices and
burrows formed by other animals (FORBES & HANLEY,
1853; JEFFREYS, 1865; TEBBLE, 1976; see also BALUK &
RADWANSKI, 1979, for a comparison of S. binghami with
its presumed Neogene ancestor, Sphenia anatina Basterot,

Page 324

A u.p.

DORSAL
LEFT VALVE

LATERAL
LEFT VALVE

Cc
LATERAL

0.5 mm

SS

Figure 4

Hinge structure of Sphenia sincera Hanks & Packer, spec. nov.,
holotype USNM 679164. A, dorsal view of chondrophore of left
valve. B, lateral view of chondrophore of left valve. C, lateral
view of resilifer of right valve. Key: b, beak or umbo; u.p., um-
bonal pit; a.b., anterior buttress; a.r., anterior ridge; |.p., liga-
mental pit; v.m., ventral or outer margin; r.g., radial groove;
m.g., median groove; p.r., posterior ridge; p.b., posterior buttress.

1825). Generally, the shell posterior is truncate or rostrate
and is usually distorted by the confines of its habitat
(STANLEY, 1970; BALUK & RADWANSKI, 1979). Often, the
posterior region of the shell is weakly calcified, which
gives flexibility to the shell, and apparently this feature
has selective value for the nestling species. Additionally,
YONGE (1951) stated that lack of mobility and the nature
of the habitat is further indicated by the presence of en-
crusting growths on the shell and periostracum of the
siphons.

In contrast, Sphenia sincera has none of the character-
istics of the typical nestling form, and has not been ob-
served in a nestling habit, although Hiatella is common
on the rocky New England coastline (THEROUX &
WIGLEY, 1983), and extensive collections were made
throughout the lower Sheepscot estuary in the dense Hia-
tella populations adjacent to deep-water populations of S.

The Veliger, Vol. 27, No. 3

Ss

Figure 5

Sphenia sincera Hanks & Packer, spec. nov. Camera lucida
drawing of holotype USNM 679164. A, left valve. B, right valve.
C, posterior. D, anterior. E, dorsal view. F, inner surface of
right valve. G, inner surface of left valve. Pallial complex usually
obscure, but has been highlighted in this drawing.

sincera. The burrows and tubes of other organisms were
also examined closely. Sphenia sincera is always found
living on or near the surface of the soft, clay-silt mud
found along the Maine coast. The shells are never dis-
torted, and the periostracum is quite thin. In most respects
they resemble the juveniles of Mya arenaria and Mya trun-
cata, but S. sincera differs from Mya in having a chon-
drophore that is more strongly arched, a reduced liga-
mental pit, an expanded radial groove, and an anterior
ridge that joins with the outer margin directly opposite or
posterior to the umbo (never anterior as in Mya). Also,
the pallial sinus is shallower and does not extend to the
middle of the shell.

R. W. Hanks & D. B. Packer, 1985

Sheepscot Estuary

Casco aA F

\
\
oe’

a
Mt. Desert

Page 325

NEW
BRUNSWICK

Gouldsboro Bay

/ NOVA
‘SCOTIA

44°

MAINE

100 Kilometers

Figure 6

Distribution of Sphenia sincera Hanks & Packer, spec. nov., in the Gulf of Maine. Dots are points of actual
collection; the 80-m contour bounds the inferred range (from Casco Bay to perhaps northeastern Nova Scotia)

based on known habitat requirements.

The unique characteristics of Sphenia sincera—bright,
clean, undistorted shell of distinct shape, solid calcifica-
tion, and geographic remoteness from other species of
Sphenia—are probably sufficient to prevent confusion with
any other species in the genus. However, specific com-
parisons help to establish the precise differences between
species and to define the new taxon.

Sphenia antillensis Dall & Simpson, 1901, appears to
be the closest living species to S. sincera both in geograph-
ic location and its generally non-nestling existence. It has
been reported from Puerto Rico (DALL & Simpson, 1901;
WARMKE & ABBOTT, 1961), Brazil (Rios, 1975), Suri-
nam (Rios, 1975), the Atlantic coast of Panama (ROSE-
WATER, 1975), and South Padre Island, Texas (ODE,
1971). Recent additions of S. antillensis to the collections
of the U.S. National Museum of Natural History have
extended its range northward. Specimens were found at
Sebastian Inlet, Florida, in 1978 (USNM 836238), and
at Cumberland Island, Georgia, in 1982 (USNM 819628).
Even though S. antillensis is the only member reported to
be living in sandy bottoms and having undistorted shells
(DALL & Simpson, 1901; WARMKE & ABBOTT, 1961; Rios,

1975), ODE (1976) mentions it as being a deformed species
found in a nestling habitat. In addition, specimens in the
U.S. National Museum of Natural History from worm
reefs in Sebastian Inlet, Florida (USNM 836238), had
the characteristic convoluted, distorted shells of a nestler.
In any case, the shell of S. antillensis is quite distinct from
S. sincera in having more acute umbones, a distinctly
flattened anterior margin not curving regularly as in S.
sincera, a broader posterior end, and an unusual concav-
ity on the posteroventral portion of the shell, giving the
shell a keeled shape. Sphenia antillensis has a yellow peri-
ostracum but, apparently, this is often missing.

LEwis (1968) has recently described Sphenia tumida from
the Pleistocene of Flagler County, Florida. Three other
fossil species recorded from this region are Sphenia dubia
(Lea, 1845), S. attenuata Dall, 1898, and S. senterfeiti
Gardner, 1936. The first is from the Miocene of Virginia
and North Carolina, the latter two from the Pliocene and
Miocene of Florida respectively. Sphenia sincera differs
in being larger and more regular in shape than S. dubia
or S. senterfeiti and in being neither attenuated, tumid, nor
rostrate as are §. attenuata and S. tumida. Of course, S.

Page 326

sincera differs in being a living species, although ODE
(1971, 1976) has reported a single valve of S. tumzda found
in Freeport, Texas, that might be recent.

Two species of Sphenia are found in the Eastern Pacific.
They are Sphenia luticola (Valenciennes, 1846) and Sphenia
ovoidea Carpenter, 1864. Sphenia luticola is apparently the
most ubiquitous member of the genus on the Pacific coast,
having been reported from Oregon to Peru (see KEEN,
1971; ABBOTT, 1974; REHDER, 1981; under the synonym
fragilis H. & A. Adams, 1854). The shell is elongate and
opaque, but not solid. The periostracum is dull yellowish-
gray to brown and adherent, but the surface of the shell
is somewhat nacreous and almost smooth, with indistinct
annuli. The posterior is attenuated, truncate, and com-
monly twisted. Internally, the shell is white; the pallial
sinus is slightly oblique and not large. The anterior ad-
ductor scar appears to be more ventrally displaced than
in most other Sphenia. Although there is considerable
variation in shell shape as a result of the nestling habit
(KEEN, 1971; REHDER, 1981), this species can be sepa-
rated from S. sincera by the yellowish-gray to brown peri-
ostracum, the attenuated posterior end, and the size and
position of the adductor scars. Sphenia ovoidea has a small
shell and occurs from the Aleutian Islands to Panama.
The anterior end of this shell is ovally rounded and the
shell bears a yellow, somewhat rugose periostracum. The
posterior end is truncate and somewhat attenuated. The
pallial sinus is large and deep, often reaching to the mid-
dle of the shell. The pallial line is quite pronounced, and
this would appear to be a good distinguishing feature in
separating the shell from S. sincera. ABBOTT (1974) lists
S. ovoidea as a possible ecologic form of Sphenia luticola.

Sphenia sincera differs from the type species, S. bing-
hami, in having a thin, deciduous periostracum rather than
a heavy, thick, brown periostracum, and in having the
posterior end undistorted, with the dorsal and ventral
margins converging rather than nearly parallel as in S.
binghami. This latter characteristic appears to be an ex-
cellent diagnostic feature, and nearly all S. binghami that
have been examined or figured have a square posterior
end. Juvenile shells exhibit this characteristic at the small-
est sizes. Of course, some larger S$. binghami become so
distorted posteriorly that the square shape is masked, but
it is still evident even in very twisted shells. Sphenia bing-
hamz has a thinly calcified posterior end, whereas the en-
tire shell is evenly calcified in S. sincera. The umbones
are usually situated less than one-third of the distance
between the anterior and posterior ends—the umbones of
S. sincera are located about one-third of the distance. The
anterior end of S. binghamz is obliquely truncate, whereas
in S. sincera it is generally rounded. The adductor scars
are larger in S. binghami; the posterior adductor scar is
wider (height two-thirds of width), as compared to that
in S. sincera (width two-thirds of height). YONGE (1951)
reported that the siphons of §. binghami are short, whereas
the siphons of S. sincera are comparatively long.

Sphenia coreanica Habe, 1951, described from the coasts

The Veliger, Vol. 27, No. 3

of Korea and Japan, is very truncate posteriorly, has a
somewhat crenulated anterior and ventral margin, and
has a discontinuous pallial line. This shell is so different
from S. sincera that there is no possibility of confusing
the two.

Identification of the species of Sphenia can be difficult
because of their small size and often extreme distortion
resulting from the nestling habit. The taxonomic status of
some specimens remains uncertain, and the genus is in
need of a thorough review in regard to taxonomy and
distribution. However, each species has distinctive mor-
phological features, and Sphenia sincera presents an ideal-
ized morphological ground plan that, by its perfection,
separates the shell from other members of the genus.

Growth and age: Measurements of the increments be-
tween successive external shell annuli were used to deter-
mine growth rates. Although growth rings have been used
to determine age and growth in mollusks, this method has
several sources of error, because ‘annuli can be caused by
any source of arrested growth in addition to that resulting
from low water temperature, including unusual environ-
mental conditions, spawning, poor feeding conditions, pre-
dation, and changes in sediment structure (NEWCOMBE,
1935, 1936a; BROUSSEAU, 1979; MACDONALD & THOMAS,
1980). However, small, fast growing, short-lived mollusks
appear to produce more discrete and predictable rings than
others (PETERSEN, 1978; BROUSSEAU, 1979).

Specimens of Sphenia sincera collected in June of 1962
were held in laboratory trays, with flowing seawater at
ambient local temperature, until February of 1963. Mea-
surements of each annulus, and overall shell length, were
made on 147 shells using the right, or largest, valve. Gen-
erally, three annuli were apparent, and can be interpreted
from smallest to largest as (1) first winter check (1961-
62), (2) check caused by collection and handling in June,
and (3) second winter (1962-63) check. Usually, the final
(second winter) check coincided with total length, but in
some specimens new growth of about 0.1 to 0.2 mm width
was noted. The mean length at the first winter check was
3.0 mm (range 1.1 to 4.6 mm), at the collection check 4.0
mm (range 2.4 to 6.1 mm), and at the final check 5.1 mm
(range 4.1 to 7.1 mm). Since this mean ultimate size is
similar to the mean size of natural populations, it is as-
sumed that laboratory growth rates were comparable to
growth in wild populations. Mean growth in one year,
under the conditions described, was a little more than 2
mm in length. The fastest growth recorded for the period
was 4.7 mm, and the slowest 0.6 mm. Slow growth was
characteristic of clams that were small at the first winter
check. Growth of Sphenia sincera is considerably less than
that reported for Mya arenaria by various authors (BEL-
DING, 1907, 1916; PACKARD, 1918; NEWCOMBE, 1935,
1936b; Dow & WALLACE, 1951; MERRILL, 1959;
STICKNEY, 1964a, b; HANks, 1968, 1969; ARBUCKLE,
1982). Mya truncata also grows at a relatively slow rate,
but even in the cold waters of coastal Greenland, the growth

R. W. Hanks & D. B. Packer, 1985

Page 327

rate appears to be twice as rapid as that of Sphenia sincera
from Maine (PETERSEN, 1978).

The maximum length of Sphenia sincera appears to be
about 1 cm; the largest specimen was taken in the Sheep-
scot region, had a total length of 9.9 mm, and had four
shell annuli. Most individuals, however, apparently live
only two to three years, and the mean size of all specimens
measured was 5.4 mm.

DISCUSSION

Sphenia sincera has been collected from depths of 10 to
80 m in the Sheepscot region. Ninety percent of the dried
sediment samples from this area consists of silt and clay.
Specimens collected from the lower third of Gouldsboro
Bay at 15 m depths were found in sediments consisting of
12% clay, 12% silt, and 76% sand, whereas collections
taken 1.5 nautical miles (2.8 km) west of Petit Manan
Island near the mouth of Gouldsboro Bay at depths rang-
ing from 37 to 44 m were found in sediments that con-
sisted on the average of 27% clay, 28% silt, and 45% sand
(Packer, unpublished data). In both Gouldsboro Bay and
the Sheepscot estuary, water temperatures near the bot-
tom range from 1°C in the winter to 14°C in the summer.
Salinities at the bottom are nearly uniform throughout the
year at about 32%. Mean tidal range for both areas is
about 3 m. This presumably has little effect on popula-
tions of animals living at the depths Sphenia inhabits.
Since the Gouldsboro populations seem to center outside
the bay in offshore waters with depths to 63 m, the tidal
effects are negligible as compared to those within the bay
(ADEY, 1982). Most of the Sheepscot population centers
in the mouth of the “lower estuary” (STICKNEY, 1959),
where the major effect of tide is on current flow, both
velocity and direction, and mixing (GARSIDE et al., 1978;
LARSEN et al., 1980).

Most faunal associates of Sphenia sincera in the Sheep-
scot are members of a general Nucula-Nephtys dominated
community described by Hanks (1964) and LARSEN
(1979). Particularly abundant in these deeper waters are
the bivalves Nucula proxima Say, 1822, Nucula annulata
Hampson, 1971, Thyasira gouldu (Philippi, 1845), juve-
nile Arctica islandica (Linné, 1767), Cerastoderma pinnu-
latum (Conrad, 1830), Yoldia limatula (Say, 1831), and
such polychaetes as Sternaspis scutata (Renier, 1807),
Nephtys incisa Malgrem, 1865, and Nephtys ciliata (O. F.
Miiller, 1789). Tube-building amphipods, such as Coro-
phium and Ampelisca, often produce thick mats of old
tubes that lace the surface sediments in which the scale-
worm Hartmania moorei Pettibone, 1955, may live as a
commensal. In Gouldsboro Bay, the community is domi-
nated by Nucula and the cumaceans Diastylis sculpta Sars,
1871, Diastylis polita (S. 1. Smith, 1879), and Eudorella
pusilla Sars, 1871, as well as such polychaetes as Scoloplos
acutus (Verrill, 1873a) and Prionospio steenstrupi Malm-
gren, 1867. Outside the bay, S. sincera may reach a den-
sity of as much as 250/m?, and is one of the dominant

soft-bottom invertebrates, along with Nucula and the poly-
chaetes Prionospio steenstrupi, Ninoe nigripes Verrill, 1873a,
and Capitella capitata (Fabricius, 1780) (Packer, unpub-
lished data).

Major predators of these Sphenia populations are bot-
tom-feeding cod, haddock, and flounder. Stomach contents
of small cod and haddock, captured near the mouth of the
Sheepscot River in June 1962, revealed that they were
feeding almost exclusively on Sphenia. One small haddock
(total length about 46 cm) contained over 400 specimens
of Sphenia, with only a few other small mollusks (Arctica
and Clinocardium). If the range of Sphenia sincera extends
along the Maine coast, and if its abundance is as great as
in the Sheepscot and Gouldsboro regions, it must be an
important food for inshore groundfish populations. In ad-
dition to the extensive use as food for fish, Sphenia sincera
is undoubtedly prey for many other animals. Three shells
collected near Mt. Desert Island (USNM 172122) and
several from Gouldsboro Bay were drilled by a gastropod.
From the tapered edges of the small hole, it is believed
that they were drilled by a naticid (CARRIKER, 1981),
common predatory gastropods found in these waters.

Sphenia sincera has the morphological characteristics
of a filter-feeding mollusk (YONGE, 1951) and could feed
on materials similar to those utilized by Mya arenaria,
such as phytoplankton (NEWCOMBE, 1935; STICKNEY,
1964a, b; ARBUCKLE, 1982). Specimens of Sphenia sincera
collected in Maine were held in artificial seawater aquaria
in the laboratory at Oxford, Maryland, from July to No-
vember 1967. During these 4 to 5 months the clams were
offered weak suspensions of Phaeodactylum and Chlorella.
Since mortalities were less than 10% during this period,
it is assumed that the clams did feed, but we could not
confirm that the algae were used. It is entirely possible
that other microorganisms may have been nutritionally
significant—there is some evidence that M. arenaria may
be a deposit-feeder as well as a suspension-feeder
(RASMUSSEN, 1973) as is true in such other bivalves as
Macoma balthica (Linné, 1758) (BRAFIELD & NEWELL,
1961). This may also be the case for Sphenia sincera, since
it appears that many benthic species are generalist feeders
(MAURER et al., 1979). Sphenia sincera may be more of
a deposit than a suspension-feeder because it is found in
high silt-clay sediments along with very large numbers of
such other deposit-feeders as Nucula proxima. Deposit-
feeders tend to be dominant in bottoms of these types
because they destabilize the soft sediments and suffocate
suspension-feeding organisms (SANDERS, 1958; RHOADS
& YOUNG, 1970; LEVINTON, 1977). Also, selective depos-
it-feeders are most sensitive to the abundance of the clay-
sized particles, a reflection of the availability of organic
detritus in the fine-grained sediment. Greater amounts of
organic matter permit larger bacterial populations that
are a food source for deposit-feeders (SANDERS, 1958;
DRISCOLL & BRANDON, 1973; LEVINTON & BAMBACH,
1975). In the Sheepscot and Gouldsboro regions abundant
detritus is available from such macrcalgae as Ulva, Fucus,

Page 328

and especially Ascophyllum (ADEY, 1982) along with the
seagrass Zostera marina Linné, 1753.

The habitats of Mya arenaria and Sphenia sincera are
separated by difference in bathymetric preference; the for-
mer species rarely extends much below the low-tide level
(THEROUX & WIGLEY, 1983), and the latter inhabits much
deeper water, deeper than 10 m with greatest abundance
below 30 m. Although it is difficult to retain the natural
relation with the bottom surface in deep-water samples,
individuals of S. sincera appear to have a similar orien-
tation to juvenile M. arenaria of the same size; that is, the
anterior end directed down and the posterior end with the
siphons directed toward the surface. The burrows do not
appear to be lined with mucus or other supportive mate-
rial. Clams held in our aquaria rarely dug into sediments,
or buried themselves partially, but this could be unusual
behavior induced by the sediments (generally sandy) used,
as it was extremely difficult to reproduce the typical sed-
iment structure of the Sheepscot region in the laboratory.
As a possible filter-feeder in such soft sediments, Sphenia
sincera is restricted to the top 25 mm of sediment due to
its short siphons, also evidenced by the prevalence of clams
of this species in the stomachs of bottom-feeding fish. Mya
arenaria, on the other hand, is a deep burrower, and in
order to maintain an open tube through which its long
siphons can be withdrawn and re-extended, it prefers to
live in a more cohesive, stable substrate, such as muddy
sand. STANLEY (1970) notes that young Mya arenaria liv-
ing in soft mud are unable to maintain permanent tubes
for their siphons.

Mya truncata is also found in the deeper waters of the
Gulf of Maine (VERRILL, 1873) but not in dense popu-
lations. Specimens have not been taken in samples for this
study or in other surveys (HANKS, 1961, 1964; LARSEN,
1979; THEROUX & WIGLEY, 1983). Scattered reports of
M. truncata along the Maine, New Brunswick, Nova Sco-
tia, and Gaspe coasts indicate that inshore populations are
widely distributed and low in density. Adult M. truncata,
obtained from the Maine coast and Canada, were all true
M. truncata and not Mya pseudoarenaria Schlesch, 1931,
which resembles M. arenaria (LAURSEN, 1966; BERNARD,
1979a, b; LUBINSKy, 1980; SIMONARSON, 1981). Extreme
phenotypes of M. truncata have a superficial resemblance
to Sphenia sincera (FOSTER, 1946), but this species of Mya
has a smaller anterior tooth in the right valve (this tooth
is not found in M. arenaria) and the anterior adductor scar
extends farther ventrally than it does in S. sincera. Al-
though M. truncata is generally subtidal in deep water
along the southern part of the Gulf of Maine, it also
occurs in shallow water and can be found intertidally on
the northern part of the Maine coast and on Canadian
shores (LUBINSKY, 1980) in all types of sediments, al-
though it frequently prefers firm clay bottoms. René La-
voie (personal communication) of the Faculty of Science,
Laval University, Quebec, P.Q., said that he found adult
M. truncata valves still joined by the ligament—indicating
fairly recent mortality—on the Gaspe shores of the St.

The Veliger, Vol. 27, No. 3

Lawrence. SMITH (1953) demonstrated that adult Mya
arenaria decayed slowly after death, and that some re-
mains of meat and adductor muscle were still evident after
three months in summer and four months in winter. We
can infer that the ligamentally joined M. truncata shells
from the St. Lawrence had been dead for at least one
year, and possibly much longer.

The evidence, therefore, indicates that Sphenia sincera
occupies a habitat different from that of adult Mya are-
naria and Mya truncata, that it does not compete for space
with juvenile Mya arenaria which live mostly in shallow
waters and intertidal regions, and that little competition
can occur with juvenile Mya truncata, which are not com-
mon in offshore Maine waters near the southern limit of
their distribution.

ACKNOWLEDGMENTS

This work forms part of Bob Hanks’ Ph.D. dissertation
at the University of New Hampshire. The guidance of
the late Dr. George M. Moore was greatly appreciated.
Dr. Emery F. Swan’s suggestions and criticisms of the
work were invaluable.

At the Smithsonian Institution, Dave Packer appreci-
ates the advice and assistance of Dr. Joseph Rosewater
and Dr. Walter H. Adey. Special thanks to Charlotte
Johnson and Bill Boykins for drafting work and photo-
graphs. Additional thanks to Jim Craig and Kimmie Pey-
ton for help with text and figures.

LITERATURE CITED

ABBOTT, R. T. 1974. American seashells. The marine molluscs
of the Atlantic and Pacific coasts of North America. Van
Nostrand Reinhold: New York. 663 pp.

ApaMS, H. & A. ADAMS. 1854. The genera of recent Mollus-
ca; arranged according to their organization. John van Voorst:
London. Vol. 2, 661 pp.

AvbEY, W. H. 1982. A resource assessment of Gouldsboro Bay,
Maine. Unpublished report to the National Oceanic and
Atmospheric Administration Marine Sanctuary Program,
Grant No. NA81AA-D-C2076. 47 pp.

ARBUCKLE, J. 1982. The soft-shelled clam and its environ-
ment: a study in Jonesboro, Maine. Maine Sea Grant Pro-
gram Report No. NA81AA-D-0035, Univ. Maine, Orono.
35 pp.

BALuK, W. & A. RADWANSKI. 1979. Shell adaptation and eco-
logical variability in the pelecypod species Sphenza anatina
(Basterot) from the Korytnica basin (Middle Miocene; Holy
Cross Mountains, Central Poland). Acta Geol. Polonica 29:
269-286.

BaSTEROT, M. B. DE. 1825. Memoire geologique sur les en-
virons de Bordeaux. Premiere partie, comprenant les obser-
vations generales sur les mollusques fossiles, et la descrip-
tion particuliere de ceux zu’ou rencontre dans ce bassin... .
Paris. Vol. 1.

BELDING, D. L. 1907. A report on the shellfisheries of Mas-
sachusetts. Pp. 46-53. In: Commonwealth of Mass., Public
Doc. No. 25, Report of the Commissioners on Fisheries and
Game for the year ending December 31, 1906. Wright and
Potter Printing Co.: Boston, Mass.

BELDING, D. L. 1916. A report upon the clam fishery. Pp. 93-

R. W. Hanks & D. B. Packer, 1985

234. In: Commonwealth of Mass., Public Doc. No. 25, Fif-
tieth Annual Report of the Commissioners on Fisheries and
Game for the year 1915. Wright and Potter Printing Co.:
Boston, Mass.

BERNARD, F. R. 1979a. Identification of the living Mya (Bi-
valvia: Myoida). Venus 38(3):185-204.

BERNARD, F. R. 1979b. Bivalve mollusks of the western Beau-
fort Sea. Contrib. Sci. Natur. Hist. Mus. Los Angeles County
313:1-80.

BERNARD, F. R. 1983. Catalogue of the living Bivalvia of the
eastern Pacific Ocean: Bering Strait to Cape Horn. Can.
Spec. Publ. Fish. Aquatic Sci. 61:1-102.

BRAFIELD, A. E. & G. E. NEWELL. 1961. The behavior of
Macoma balthica (L.). J. Mar. Biol. Assoc. U.K. 41:81-87.

BroussEAu, D. J. 1979. Analysis of growth rate in Mya ar-
enaria using the Von Bertalanffy equation. Mar. Biol. 51:
221-227.

CARPENTER, P. R. 1864. Supplementary report on the present
state of our knowledge with regard to the Mollusca of the
west coast of North America. British Assoc. Adv. Sci. Rep.
33 (for 1863):517-686.

CARRIKER, M. R. 1981. Shell penetration and feeding by nat-
icacean and muricacean predatory gastropods: a synthesis.
Malacologia 20(2):403-422.

ConraD, T. A. 1830. Description of fifteen new species of
recent, and three fossil shells, chiefly from the coast of the
United States. J. Acad. Natur. Sci. Phila. 6:256-268.

Dat, W. H. 1898. Contribution to the Tertiary fauna of
Florida, with especial reference to the Silex beds of Tampa
and the Pliocene beds of the Caloosahatchie River, including
in many cases a complete revision of the generic groups
treated of and their American Tertiary species. Part IV:
Prionodesmacea, Nucula to Julia; Teleodesmacea, Teredo to
Ervilia. Trans. Wagner Free Inst. Sci. Phila. 3, pt. 4:571-
947.

DALL, W. H. & C. T. Simpson. 1901. The mollusca of Porto
Rico. Bull. U.S. Fish Comm. 20:351-524.

Davis, J. D. 1964. Mesodesma deauratum: synonymy, holotype,
and type locality. Nautilus 78(1):96-100.

Dow, R. L. & D. E. WaLLace. 1951. Soft-shell clam growth
rates in Maine. Unpublished mimeo report available from
authors. Maine Dept. Sea and Shore Fish., Augusta, Maine.
10 pp.

DRISCOLL, E. G. & D. E. BRANDON. 1973. Mollusc-sediment
relationships in northwestern Buzzards Bay, Massachusetts,
U.S.A. Malacologia 12(1):13-46.

FIscHER, P. H. [1880]-1887. Manuel de conchyliologie et de
paléontologie conchyliologique ou histoire naturelle des
mollusques vivants et fossiles suivi d’un appendice sur les
brachiopodes par D. P. Oehlert. Paris. 1369 pp.

Fores, E. & S. HANLEY. 1853. A history of British Mollusca
and their shells. John van Voorst: London. Vol. 1, 486 pp.

Foster, R. W. 1946. The genus Mya in the western Atlantic.
Johnsonia 2(20):29-35.

Fujiz, T. 1957. On the myarian pelecypods of Japan. Part 1.
Summary of the study of the genus Mya from Hokkaido. J.
Hokkaido Univ. Fac. Sci. (4th ser.) 9(4):381-413.

GARDNER, J. 1936. Additions to the molluscan fauna of the
Alum Bluff Group of Florida. Florida Geol. Surv., Bull.
14:7-82.

GarsIDE, C., G. HULL & C. S. YENTSCH. 1978. Coastal source
waters and their role as a nitrogen source for primary pro-
duction in an estuary in Maine. Pp. 565-575. In: M. L.
Wiley (ed.), Estuarine interactions. Academic Press: New
York.

Gray, J. E. 1847. A list of the genera of Recent Mollusca,

Page 329

their synonyma and types. Proc. Zool. Soc. Lond. 15(15):
129-219.

Hase, T. 1951. Donacidae and Myidae in Japan. Pp. 71-78.
In: T. Kuroda (ed.), Illustrated catalogue of Japanese shells,
1949-1953. Vol. 1. Kyoto, Japan.

Hampson, G. R. 1971. A species pair of the genus Nucula
(Bivalvia) from the eastern coast of the United States. Proc.
Malacol. Soc. Lond. 39:333-342.

Hanks, R. W. 1961. A study of the macroscopic benthic fauna
of an estuary on the coast of Maine. Master’s Thesis, Univ.
New Hampshire, Durham. 99 pp.

Hanks, R. W. 1964. A benthic community in the Sheepscot
River estuary, Maine. U.S. Fish Wild. Serv., Fish. Bull.
63(2):343-353.

Hanks, R. W. 1968. Benthic community formation in a “new”
marine environment. Chesapeake Sci. 9(3):163-172.

Hanks, R. W. 1969. The soft-shell clam industry. Pp. 112-
119. In: F. R. Firth (ed.), Encyclopedia of marine resources.
Van Nostrand-Reinhold Co.: New York.

JEFFREYS, J. G. 1865. British conchology, or an accounting of
the Mollusca which now inhabit the British Isles and the
surrounding seas. John Van Voorst: London. Vol. 3., 393

PP-

KEEN, A. M. 1971. Sea shells of tropical West America: ma-
rine mollusks from Baja California to Peru. Stanford Univ.
Press: Stanford, Calif. 1064 pp.

LAMARCK, J. B. DE. 1809. Philosophie zoologique, ou expo-
sition des considérations relatives a l’histoire naturelle des
animaux, la diversité de leur organisation et des facultés
quwils en obtiennent, aux causes physiques qui maintiennent
en eux la vie, et donnent lieu aux mouvements qu’ils exé-
cutent; enfin, a celles qui produisent les unes les sentiments,
et les autres l’intelligence de ceux qui en sont doués. Paris.
Vols. 1 & 2, pp. 1-422, 1-473.

Lamy, E. 1919. Revision des Myidae vivants du Museum
National d’Histoire Naturelle de Paris. J. Conchyl. 70:151-
185.

LaRSEN, P. F. 1979. The shallow-water macrobenthos of a
northern New England estuary. Mar. Biol. 55:69-78.
LaRSEN, P. F., L. DoGGETT, C. GarsIDE, J. TOPINKA, T. MAGUE,
T. GARFIELD, R. GERBER, S. FEFER, P. SHETTIG & L.
THORNTON. 1980. The estuarine system. Pp. 5-1-5-148.
In: S. I. Fefer & P. A. Schettig (eds.), An ecological char-
acterization of coastal Maine. Vol. 2. U.S. Fish and Wild.
Serv., Biol. Serv. Prog., Northeast Region, Massachusetts.

LaAuRSEN, D. 1966. The genus Mya in the Arctic region. Mal-
acologia 3(3):399-418.

Lea, H. C. 1845. Description of some new fossil shells, from
the Tertiary of Petersburg, Virginia. Trans. Amer. Philo.
Soc., ser. II, 9:229-274.

LEVINTON, J. S. 1977. Ecology of shallow water deposit-feed-
ing communities Quisset Harbor, Massachusetts. Pp. 191-
227. In: B. C. Coull (ed.), Ecology of marine benthos. Univ.
South Carolina Press: Columbia, South Carolina.

LEVINGTON, J. S. & R. K. BAMBACH. 1975. A comparative
study of Silurian and recent deposit-feeding bivalve com-
munities. Paleobiology 1:97-124.

Lewis, J. E. 1968. Taxonomy and paleoecology of a new species
of Sphenia (Bivalvia; Myidae) from the Pleistocene of Flor-
ida. Tulane Stud. Geol. 6(1):23-32.

LINNE, C. von. 1758. Systema naturae per regna tria naturae
.... Edit. decima, reformata. Vol. 1. Regnum Animale.
Laurentii Salvii: Stockholm. 824 pp.

LINNE, C. von. 1767. Systema naturae per regna tria naturae
.... Edit. duodecima, reformata. Vol. 1. Regnum Animale.
Laurentii Salvii: Stockholm. Pt. 2:533-1327.

Page 330

The Veliger; Volo 27 Nioms

Lusinsky, I. 1980. Marine bivalve molluscs of the Canadian
Central and Eastern Arctic: faunal composition and zooge-
ography. Can. Bull. Fish. Aquat. Sci. 207:1-111.

MacDonaLp, B. H. & M. L. H. THomas. 1980. Age deter-
mination of the soft-shell clam Mya arenaria using shell
internal growth lines. Mar. Biol. 58:105-109.

MAacNEIL, F. S. 1965. Evolution and distribution of the genus
Mya, and Tertiary migrations of Mollusca. U.S. Geol. Surv.
Prof. Pap. 483-G:1-51.

Maurer, D., L. WATLING, W. LEATHEM & P. KINNER. 1979.
Seasonal changes in feeding types of estuarine benthic in-
vertebrates from Delaware Bay. J. Exp. Mar. Biol. Ecol.
36:125-155.

MERRILL, A. S. 1959. An unusual occurrence of Mya arenaria
L. and notes on other marine mollusks. Nautilus 73(2):39-
43.

NeEwcoMBE, C. L. 1935. Growth of Mya arenaria L. in the
Bay of Fundy region. Can. J. Res. 13:97-137.

NEWCOMBE, C. L. 1936a. Validity of concentric rings of Mya
arenaria L. for determining age. Nature 137:36.

NEWCOMBE, C. L. 1936b. A comparative study of the abun-
dance and the rate of growth of Mya arenaria in the Gulf of
St. Lawrence and Bay of Fundy regions. Ecology 17(3):
418-428.

Nico., D. 1958. A survey of inequivalve pelecypods. J. Wash.
Acad. Sci. 48(2):56-62.

Ove, H. 1971. Sphenia tumida Lewis, 1968 from Bryan Beach,
Freeport, Texas. Texas Conchologist 7(7):79-80.

OpvE, H. 1976. Distribution and records of the marine Mol-
lusca in the northwest Gulf of Mexico (a continuing mono-
graph). Texas Conchologist 13(1):16-32.

PACKARD, E. L. 1918. A quantitative analysis of the molluscan
fauna of San Francisco Bay. Univ. Calif. Publ. Zool. 18(13):
299-336.

PETERSEN, G. H. 1978. Life cycles and population dynamics
of marine benthic bivalves from the Disko Bugt area of West
Greenland. Ophelia 17(1):95-120.

PHILIPPI, R. A. 1845. Bemerkungen tiber die Mollusken fauna
von Massachusetts. Z. Malakozool. 2:68-79.

RASMUSSEN, E. 1973. Systematics and ecology of the Isefjord
marine fauna (Denmark). Ophelia 11:1-495.

REHDER, H. A. 1981. The Audubon Society field guide to
North American seashells. Alfred A. Knopf: New York. 894

PP-

RuHoaps, D. C. & D. K. Younc. 1970. The influence of de-
posit-feeding organisms on sediment stability and commu-
nity trophic structure. J. Mar. Res. 28:150-178.

Rios, E. C. 1975. Brazilian marine mollusks iconography.
Fundacao Universidade do Rio Grande Centro de Ciéncias
do Mar Museu Oceanografico, Rio Grande. 331 pp.

ROSEWATER, J. 1975. Mollusks of Gatun Locks, Panama Ca-
nal. Bull. Amer. Malacol. Union 1974:42-43.

SANDERS, H. L. 1958. Benthic studies in Buzzards Bay. I.
Animal-sediment relationships. Limnol. Oceanogr. 3:245-
258.

Say, T. 1822. An account of some of the marine shells of the
United States. J. Acad. Natur. Sci. Phila. 2:221-248, 257-
276, 302-325.

Say, T. 1831. American conchology; or, descriptions of the
shells of North America. Illustrated by colored figures from
original drawings executed from nature. New Harmony,
Indiana. Pt. 2, pp. 151-170.

SCHLESCH, H. 1931. Beitrag zur Kenntnis der marinen Mol-
lusken-Fauna Islands. 2 Studien tiber Mya-Arten. Arch.
Molluskenkd. 63:133-155.

SIMONARSON, L. A. 1981. Upper Pleistocene and Holocene
marine deposits and faunas on the north coast of Nugssuaq,
West Greenland. Grenlands Geologiske Undersggelse 140:
1-107.

SMITH, E. A. 1893. Observations on the genus Sphenia, with
descriptions of new species. Ann. Mag. Natur. Hist. 12(6):
277-281.

SMITH, O. R. 1953. Observations on the rate of decay of soft-
shell-clams (Mya arenaria). Ecology 34(3):640-641.

STANLEY, S. M. 1970. Relation of shell form to life habits of
the Bivalvia (Mollusca). Mem. Geol. Soc. Amer. 125:296
PP-

STICKNEY, A. P. 1959. Ecology of the Sheepscot River estuary.
USS. Fish Wildl. Serv., Spec. Sci. Rep., Fish. 309:1-21.
STICKNEY, A. P. 1964a. Salinity, temperature, and food re-
quirements of soft-shell clam larvae in laboratory culture.

Ecology 45(2):283-291.

STICKNEY, A. P. 1964b. Feeding and growth of juvenile soft-
shell clams, Mya arenaria. U.S. Fish Wild. Ser., Fish. Bull.
63(3):635-642.

TEBBLE, N. 1976. British bivalve seashells, a handbook for
identification. British Museum (Natur. Hist.): London. 212
PP-

THEROUX, R. B. & R. L. WIGLEY. 1983. Distribution and
abundance of east coast bivalve mollusks based on specimens
in the National Marine Fisheries Service Woods Hole col-
lection. Natl. Mar. Fish. Ser., Spec. Sci. Rep., Fish. 768:1-
2:

TRUEMAN, E. R. 1954. Observations on the mechanism of the
openings of the valves of a burrowing lamellibranch, Mya
arenaria. J. Exp. Biol. 31(2):291-305.

Turton, W. 1822. Conchylia dithyra Insularum Britannica-
rum, the bivalve shells of the British Isles, systematically
arranged. Quarto, London (1848). 279 pp. [Reprinted ver-
batim from the original (1822) edition entitled: ““Conchlyia
Insularum Britannicarum, the shells of the British Islands
systematically arranged.’

VALENCIENNES, A. 1846. Mollusques. Pl. 24 (no text). Jn: Abel
du Petit-Thouars (ed.), Voyage autor du monde sur la fre-
gate La Venus, pendant ... 1836-1839. Atlas de Zoologie,
Mollusques. Paris.

VERRILL, A. E. 1873. Report upon the invertebrate animals
of Vineyard Sound and the adjacent waters with an account
of the physical characters of the region. Rep. U.S. Fish
Comm. for 1871-1872, 1:295-778.

WaARMEKE, G. L. & R. T. ABBoTr. 1961. Caribbean seashells,
a guide to the marine mollusks of Puerto Rico and other
West Indian Islands, Bermuda and the lower Florida Keys.
Livingston Publ. Co.: Narberth, Pa. 346 pp.

YONGE, C. M. 1951. Observations on Sphenia binghami Tur-
ton. J. Mar. Biol. Assoc. U.K. 30(2):387-392.

The Veliger 27(3):331-335 (January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

An Anesthetic for Internal Operations on the

Land Snail Helix aspersa Miiller

by

DANIEL CHUNG

Museum of Zoology and Division of Biological Sciences,
University of Michigan, Ann Arbor, Michigan 48109

Abstract.

An anesthetic solution consisting of 2% magnesium chloride and 0.01% succinylcholine

chloride in combination was used to anesthetize Helix aspersa for internal operations. A dosage of 0.012
mg of succinylcholine per gram of snail tissue and 2.4 mg/g MgCl,-6H,O was injected into the hemocoel
to produce a quick and pronounced anesthesia with a nearly 100% survival rate. The combined action
of the two drugs at low dosages resulted in an anesthesia better than either drug alone at high dosages.
At a higher dosage, the new anesthetic solution also worked on Arion circumscriptus and may be useful

for operations on other land snails.

INTRODUCTION

A LARGE NUMBER OF agents is used for relaxing gastro-
pods. RUNHAM et al. (1965) reviewed the effectiveness of
a number of narcotizing agents used to relax snails before
fixation in an extended position and anesthetics used for
relaxing snails prior to operations. Proper relaxation must
leave living snails in an extended position and insensitive
to touch and to chemicals. Agents that have been tried on
snails in recent years include CO,, hypothermia, dilute
formalin, dilute seawater, menthol, propylene phenoxytol,
ether, urethane, tricaine (MS-222), Stovaine, Nembutal
(see RUNHAM et al., 1965), succinylcholine chloride (BEE-
MAN, 1968; BURTON, 1975), curare, Novocaine, Xylo-
caine, methohexital sodium (BEEMAN, 1968), calcium-free
seawater, Benzocaine, procaine hydrochloride (Novo-
caine) (STIRLING et al., 1984), manganese sulfate (YESCOTT
& HANSEN, 1976), pentobarbital (MEIER-BROOK, 1976),
magnesium chloride (numerous authors, including
RUNHAM ef al., 1965; TURNER, 1976), Althesin, benzyl
alcohol, quinaldine, xylazine (BOURNE, 1984), nicotine,
dilute ethanol, and various combinations of these agents.
Those reported to be useful for internal operations on
gastropods include propylene phenoxytol, magnesium
chloride, Nembutal/MS-222 (evaluated by RUNHAM et
al., 1965), CO, (BAILEY, 1969), Nembutal/MgCl, (JEP-
PESEN, 1976), and isotonic MgCl, (ROBERTS & BLOCK,
1982). BURTON (1975) reported that succinylcholine chlo-
ride was useful for anesthetizing Helix pomatia Linnaeus
for tentacle excision. RUNHAM et al. (1965) reported that
urethane and ether left snails imperfectly relaxed and was

found to be suitable only for external operations, although
MALEK & CHENG (1974) recommended both agents with
the use of physical retraction.

The effectiveness of many anesthetic agents has been
frequently reported to vary widely among species, though
a few agents, such as Nembutal and MgCl,, have been
used successfully on numerous species.

I have tried various combinations and dosages of MgCl,
Nembutal (sodium 5-ethyl-5-[1-methylbuty]]-barbiturate,
or pentobarbital sodium), MS-222 (ethyl m-aminoben-
zoate methanesulfonate, or tricaine), and succinylcholine
chloride in an effort to obtain a quick, injectable anesthetic
for internal operations on Helix aspersa Miiller. Injection
of Nembutal and MS-222 did not relax Helix aspersa well,
so no further trials of MS-222 were conducted. The meth-
ods described by JEPPESEN (1976) and BURTON (1975) for
Helix pomatia gave the most satisfactory results, but were
either time-consuming and/or led to unacceptable mor-
tality rates and difficulty during surgery. I report here a
quick-acting anesthetic solution with a high survival rate
that may also be useful for other large land snails. The
results of some preliminary trials of injections of MgCl,,
Nembutal, and succinylcholine chloride are presented to
facilitate discussion of the effect of the working anesthetic
solution.

MATERIALS, METHODS, anp TECHNIQUE
Preliminary Trials

Healthy adult and subadult specimens of Helix aspersa
obtained from California were used to test various con-

Page 332

Table 1

The dosage and evaluation of anesthetic solutions on Helix
aspersa. Dosage is in mg of drug per gram of snail tissue
(weight of whole snail minus weight of shell). Evaluation:
good (G) for full anesthesia, fair (F) for partial anesthesia
adequate for very quick surgery, unsatisfactory (U) for
poor relaxation and high irritability of the snail, and no
effect (NE) for no response to the injected solution. SChCl
= succinylcholine chloride.

Num-
ber of
: snails Evaluation
Approximate —in-

Solution dosage jected G F U NE
10% MgCl, 12.0 mg/g 11 i es) 7
5% MgCl, 6.0 mg/g 11 2 9
2% MgCl, 2.4 mg/g 10 10
0.25% SChCl 0.30 mg/g 12 12
0.05% SChCl 0.06 mg/g 13 3) @)
0.01% SChCl 0.012 mg/g 14 14
0.25% Nembutal 0.30 mg/g 11 11
0.1% Nembutal 0.12 mg/g 10 10
2% MgCl,/ 2.4 mg/g 10 10
0.1% Nembutal 0.12 mg/g
2% MegCl,/ 2.4 mg/g 10 10
0.05% SChCl 0.06 mg/g
2% MgCl,/ 2.4 mg/g 98 98
0.01% SChCl1/ 0.012 mg/g
0.005% Strepto-

mycin sulfate 0.006 mg/g
0.05% Strepto-

mycin sulfate 0.06 mg/g 9 9

centrations and combinations of MgCl,, Nembutal, and
succinylcholine chloride (Table 1). Snails weighing 4 to
7 g were injected through the thin body wall of the upper
left region of the head-foot just below the mantle collar
(the “nuchal” region). The snails were washed and al-
lowed to crawl around until the shell could be lifted and
tilted so that the “nuchal” region was exposed; the injec-
tion was then made into the hemocoel. Mild massage of
the head-foot facilitated an even distribution of the anes-
thetic. All the snails of each group received approximately
the same dosage. The effectiveness of the solution injected
was judged by its ability to: (1) render the snail immobile
and unresponsive to pinches on the side of the head-foot,
(2) keep the snail completely insensitive for at least 10
min after the injection, and (3) wear off within one or
two days. The anesthetic was judged to be good (G) if all
these criteria were met, fair (F) if the criteria were met
partly with the snail slightly reactive to touch, but relaxed
enough for minor external or quick internal surgery, un-
satisfactory (U) if none of the criteria were met or if the
snail remained very reactive to pinches of the body wall,
and with no effect (NE) if the snail showed no change or
slowing of movement.

The Veliger, VolyZjpaiens

Working Anesthetic Solution and Technique

Ninety-eight healthy adult and subadult specimens of
Helix aspersa were injected with approximately 0.4 to 0.7
mL of the following solution:

2% MgCl,-6H,0

0.01% succinylcholine chloride (Sigma Chem. Co., St.
Louis, Missouri)

0.005% streptomycin sulfate

w/v, in distilled H,O.

The solution was prepared immediately before use and
remained effective for one day. The snails were injected
with a volume that delivered an approximate dosage of
0.012 mg of succinylcholine chloride per gram of snail
tissue (weight of whole snail minus weight of shell). This
amounted to about 0.65 mL for an average-sized snail
with a tissue weight of 5.4 g (6.3 g for the whole snail).
The volume of anesthetic was roughly proportional to body
weight. This seemed reasonable considering the fact that
respiration in helicids has been reported to be nearly
proportional to weight (see GHIRETTI & GHIRETTI-
MaGAa_pI, 1975). The weight of the snail tissue was
calculated from the weight of the whole snail using a
regression line previously obtained from 38 specimens of
H. aspersa: Y = 0.884X% — 0.155, where Y is tissue weight
in grams (weight of whole snail minus weight of shell)
and X is weight of the whole snail in grams; 7 = 0.975,
Y ranging from 3.5 to 8.0 g. Snails were injected in the
manner described above. In order to check for the possible
anesthetic effect of the antibiotic streptomycin sulfate, a
few snails were injected with a 0.05% streptomycin solu-
tion, which was 10 times the concentration in the anes-
thetic solution. Antibiotics have been reported to have an
anesthetic effect in mammals (see GILMAN et al., 1980).
Survival of snails undergoing surgery seemed to depend
on retention of body fluids during surgery and on allowing
sufficient rest during recuperation. For surgery on the
terminal genitalia, the head-foot of the snail was placed
on a dissection dish so that the shell lay in a shell-shaped
depression in the wax. With the shell lying in a depres-
sion, most of the body fluids remained in the visceral he-
mocoel, and loss of fluid in short operations was usually
less than 0.2 mL. The incision was sutured with fine
surgical silk using a No. 2 eye type, half-curved needle
(George Tiemann & Co., New York). Snails were then
placed into clean, dry containers and allowed to estivate
for one week. The sutures were removed after this period
of estivation. Two snails that appeared dehydrated and ill
after surgery were put into containers lined with moist
soil and given carrots to feed on for one week before the
sutures were removed. The operations performed included
excision of parts of the genitals and implantation of tissue
from other snails into the hemocoel. The fully recovered
snails were kept in soil-lined containers and fed carrots.
Fifteen specimens of Avion circumscriptus Johnston were
injected to determine the effect of the working anesthetic

-D. Chung, 1985

solution on other snails. Seven of these slugs were cut open
and then sutured; the other eight were undisturbed. The
slugs were given a dosage of about 0.25 mg succinylcho-
line per gram body weight, about 20 times the dosage for
Helix aspersa; this dosage was necessary for complete an-
esthesia during surgery. The slugs weighed 0.45 g on av-
erage and had a maximum body length of 25 mm. Anes-
thetized slugs were put into containers with moist paper
towels until they recovered. The anesthetic solution was
also tried as a soaking solution on 10 specimens of Biom-
phalaria glabrata (Say). I observed the state of anesthesia
but did not operate on these snails.

RESULTS
Preliminary Trials

The results of the preliminary trials are shown in Table
1. The effect of each solution was generally very uniform,
even though the numbers of snails injected in these pre-
liminary trials were small. Snails injected with the MgCl,
solution recovered quickly from its effects—all were able
to crawl within 30 min after injection. Snails receiving a
10% solution showed a wide range of reactions; most snails
remained sensitive to pinches, though some remained fair-
ly insensitive long enough for quick internal operations.
Those receiving a 5% solution writhed when pinched on
the side of the head-foot and began to crawl again 15 min
after the injection. Those snails receiving a 2% solution
never became completely anesthetized and continuously
writhed slowly. Only one injection of the 32 snails receiv-
ing the MgCl, solutions resulted in a rating of good (G).
Snails injected with Nembutal never became fully anes-
thetized. Those injected with the 0.25% solution slowly
withdrew into the shell or writhed when touched. Those
injected with the 0.1% solution writhed slowly and con-
tinuously; they appeared to be trying to crawl but seemed
unable to coordinate their movements.

Snails injected with different concentrations of succi-
nylcholine chloride showed an odd trend. Those receiving
high dosages (0.25%) withdrew their heads after injection
and remained highly reactive to light touch thereafter.
Those receiving a lower dosage (0.05%) became insensi-
tive to touch for 2 to 4 min after injection, long enough
for quick external operations. Snails injected with the low-
est dosage (0.01%) were insensitive for only about 1 to 2
min and subsequently recovered. None of the injections of
39 snails receiving the succinylcholine chloride injections
was rated as good (G).

Those snails that received a solution of 2% MegCl,/
0.01% Nembutal became limp and extended, but writhed
when pinched. Snails injected with a solution of 2%
MgCl,/0.05% succinylcholine chloride became fully anes-
thetized long enough for operations. The nine snails in-
jected with 0.05% streptomycin sulfate showed no slowing
of movement or narcosis of any kind.

All snails recovered the ability to crawl within 24 h
after injection. All snails became reactive to stimuli many

Page 333

hours before they could crawl again, except for those that
received MgCl,.

Differences between different dosages for any one drug
are not statistically significant because of low sample
number and an insufficient number of ranks, but the dif-
ferences in the effects between the MgCl,/succinylcholine
mixture and the pure MgCl, or pure succinylcholine so-
lutions (all dosages pooled) are significant, since they show
almost no overlap in their effects (as evaluated in Table

1).

Working Anesthetic Solution

The working anesthetic solution of 2% MgCl,, 0.01%
succinylcholine chloride, and 0.005% streptomycin sulfate
gave excellent results during operations on 98 snails. The
revival rate after the operation and survival rate after one
week were both 100%.

The snails anesthetized by this solution became limp
and flaccid within a few seconds after injection. They
remained insensitive to pinches and touch for at least 10
min after injection. After this time, the tentacles and labial
region first regained sensitivity to stimuli, and snails
pinched in these places showed some snout retraction mo-
mentarily. More than 50% of the operated snails started
to crawl again within 6 h after injection, and all snails
had recovered the ability to crawl within a day after the
injection.

The combination of the two drugs in the working so-
lution worked better than either drug alone, even at high
dosages. A somewhat stronger dosage of succinylcholine
(0.05%) when used with MgCl, (see Table 1) was also
effective and may be useful for longer operations.

While under the anesthetic, the snails stopped secreting
mucus and the pneumostome stopped its rhythmic open-
ing and closing. During operations, the cut surface of the
incision on the body wall curled inward slightly and the
region around the incision shrank somewhat. This local
response could not be abolished at higher dosages, but it
did not cause much difficulty with the surgery and helped
reduce loss of blood. Blood loss during surgery, deter-
mined by measuring the volume of hemolymph remaining
in the dissection dish, remained less than 0.2 mL and
averaged 0.05 mL, though the volume of fluid loss would
depend on the type of surgery being performed.

Arion circumscriptus injected with the working anes-
thetic solution at a dosage 20 times that given to Helix
aspersa became fully anesthetized within a few seconds.
The local skin tightening response was more pronounced
than in H. aspersa, probably due to the greater muscular-
ity of the body wall in the slug. The slugs began recover-
ing from the anesthesia within 30 min after injection. All
15 slugs were able to crawl 2 h after injection.

The anesthetic solution could not be used as a soaking
solution on the basommatophoran Biomphalaria glabrata.
These snails slowly withdrew deep into their shells and
would not re-emerge until restored to freshwater. They

Page 334

could not be injected, because they remained too sensitive
to touch.

DISCUSSION

The new anesthetic solution reported here appears to work
better than other anesthetics reported for Helix aspersa.
The combination of succinylcholine chloride and MgCl,
acts better than either drug alone, perhaps because of po-
tentiation of succinylcholine by magnesium ion. Of the
solutions tried in the preliminary trials, 10% MgCl,, 0.05%
succinylcholine chloride, and to a lesser degree 5% MgCl,
appeared to be suitable for quick or external surgery. The
contractions that occurred during surgery on snails given
these solutions were manageable for a short period im-
mediately after injection. However, contractions of the
snails increased blood loss and difficulty of surgery.
RUNHAM et al. (1965) reported a survival rate of 85% one
week after surgery on Helix aspersa injected with 10%
MgCl, (I estimate a dosage of about 5.8 mg MgCl, per
gram of snail tissue from their figures). JEPPESEN (1976)
reported about an 80% survival rate six months after sur-
gery on Hf. pomatia anesthetized by soaking in a 0.1%
Nembutal solution followed by injection of up to 1 mL of
10% MgCl,. BURTON (1975) used a dosage of 0.1 mg to
0.017 mg succinylcholine chloride per snail for tentacle
excision; this is a dosage of roughly 0.01-0.17 mg/g, if
H. pomatia tissue weighs an average of 10 g. I estimate
that BEEMAN (1968) used a dosage of 0.013 mg/g of suc-
cinylcholine to produce a state of reversible narcosis in
Aplysia. These dosages are comparable to or higher than
the dosages of these drugs in the working anesthetic used
on H. aspersa—0O.012 mg/g succinylcholine, 2.4 mg/g
MgCl.

The combination of MgCl, and succinylcholine pro-
duces a pronounced anesthesia. The mechanism for this
action in Helix aspersa is unknown. However, it is known
that in man and cats magnesium ion potentiates the effect
of succinylcholine and other muscle relaxants (MorRRIS &
GIESECKE, 1968; GIESECKE et al., 1968; GHONEIM & LONG,
1970). Magnesium ion has been demonstrated to reduce
the release of acetylcholine at the neuromuscular junction
in vertebrates (DEL CASTILLO & ENGBAEK, 1954) in a
manner similar to that produced by lack of calcium ion
(see HUBBARD, 1973). Succinylcholine is an antagonist to
acetylcholine in neurons of the subesophageal ganglia of
Helix aspersa (WALKER & HEDGES, 1967) and is known
to produce a neuromuscular block in humans and verte-
brates by blocking the action of acetylcholine on the post-
synaptic membrane of the neuromuscular junction (see
GILMAN et.al., 1980). Concurrent application of the two
drugs produces an additive effect (GIESECKE et al., 1968;
GHONEIM & LONG, 1970). In contrast, I could find no
indication of an increase in effect when Nembutal (a bar-
biturate) and MgCl, were used together. In humans, bar-
biturates are hypnotics that work on the central nervous
system and have almost no peripheral effect (see GILMAN

The Veligers Volk 2ZieaNons

et al., 1980). I have used a combination of Nembutal,
MgCl, and succinylcholine chloride injected immediately
after mixing for operations on more than 250 H. aspersa,
with a survival rate of nearly 100%, but such a combi-
nation was no more effective than the solution not con-
taining the Nembutal.

The interaction between magnesium ion and succinyl-
choline may be undesirable in humans, but it may be
useful to investigators working on snails. The use of agents
with similar action may explain the effectiveness of the
narcotizing technique reported by STIRLING e¢ al. (1984).
Their sequential use of calcium-free seawater, MgCl, and
procaine hydrochloride (Novocaine) on veligers may affect
nerve endings. In vertebrates, calcium ion functions to
release acetylcholine at the synapse and is antagonized by
magnesium (see HUBBARD, 1973), and procaine makes
nerves less permeable to ions.

The test of the new anesthetic on Biomphalaria glabrata
indicates that the anesthetic cannot be used as a soaking
solution and probably must be injected to anesthetize the
snail and simultaneously extend the body from the shell.
Extension of the head-foot from the shell is important in
operations on shelled gastropods. In slug forms, anesthesia
may not be necessary, provided that physical immobili-
zation is used. HARLEY & HARLEY (1973) operated on
large Aplysia californica without anesthesia and obtained
a good survival rate if the weight loss during the operation
was kept below 15% of the pre-operative value. A good
anesthetic must leave the snail well extended from the
shell and prevent major contraction during surgery to re-
duce blood loss. The successful use of the new anesthetic
on Arion circumscriptus indicates that the anesthetic so-
lution might be used successfully on other land snails.

ACKNOWLEDGMENTS

I thank Dr. Alex Tompa for suggesting succinylcholine
chloride as an anesthetic and in supporting and assisting
my research on Helix. I am grateful to Dr. James Cather
for providing the Nembutal. I thank Dr. A. Tompa and
John Petranka for reading and making useful comments
on the manuscript. My work on Helix has been supported
in part by a grant from the Hawaiian Malacological So-
ciety and grants from the University of Michigan.

LITERATURE CITED

BaILey, T. G. 1969. A new anesthetic technique for slugs.
Experientia 25:1225.

BEEMAN, R. D. 1968. The use of succinylcholine and other
drugs for anesthetizing or narcotizing gastropod mollusks.
Pubbl. Staz. Zool. Napoli 36:267-270.

BourNE, G. B. 1984. Anesthetic methods for the moon snail
Polinices lewisn. Veliger 26:327-329.

BurTon, R. F. 1975. A method of narcotizing snails (Helix
pomatia) and cannulating the haemocoel and its application
to a study of the role of calcium in the regulation of acid-
base balance. Comp. Biochem. Physiol. 52A:483-485.

DEL CasTILLo, J. & L. ENGBAEK. 1954. The nature of the

D. Chung, 1985

neuromuscular block produced by magnesium. J. Physiol.
124:370-384.

GHIRETTI, F. & A. GHIRETTI-MAGALDI. 1975. Respiration.
Pp. 33-52. In: V. Fretter & J. Peake (eds.), Pulmonates,
Vol. 1. Academic Press: New York.

GHONEIM, M. M. & J. P. Lonc. 1970. The interaction be-
tween magnesium and other neuromuscular blocking agents.
Anesthesiology 32:23-27.

GIESECKE, A. H., R. E. Morris & C. R. STEPHEN. 1968. Of
magnesium, muscle relaxants, toxemic parturients, and cats.
Anesth. Analg. 47:689-695.

GILMAN, A. G., L. S. GOODMAN & A. GILMAN. 1980. The
pharmacological basis of therapeutics. 6th edition. The
Macmillan Co.: New York.

HARLEY, P. & E. HaRuey. 1973. A technique for cutting or
accessing nerves and connectives in Aplysia californica. Comp.
Biochem. Physiol. 45A:389-392.

HusBarD, J. I. 1973. Microphysiology of vertebrate neuro-
muscular transmission. Physiol. Rev. 53:674-723.

JEPPESEN, L. L. 1976. The control of mating behaviour in
Helix pomatia L. (Gastropoda: Pulmonata). Anim. Behav.
24:175-290.

MALEK, E. A. & T. C. CHENG. 1974. Medical and economic
malacology. Academic Press: New York.

Page 335

MEIER-Brook, C. 1976. An improved relaxing technique for
mollusks using pentobarbital. Malacol. Rev. 9:115-117.
Morris, R. & A. H. GIESECKE. 1968. Potentiation of muscle
relaxants by magnesium sulfate therapy in toxemia of preg-

nancy. South. Med. J. 61:25-28.

Roserts, M. H. & G. D. BLock. 1982. Dissection of circa-
dian organization of Aplysia through connective lesions and
electrophysiological recording. J. Exp. Zool. 219:39-50.

RunuHaM, N. W., K. ISARANKURA & B. J. SMITH. 1965. Meth-
ods for narcotizing and anesthetizing gastropods. Malacol-
ogia 2:231-238.

STIRLING, P., C. LitTLe, M. C. PILKINGTON & J. B. PiL-
KINGTON. 1984. Technique for narcotizing and fixing ve-
liger larvae of Amphibola crenata. Veliger 26:229-232.

TurRNER, R. D. 1976. Fixation and preservation of molluscan
zooplankton. Monogr. Oceanogr. Method. No. 4:290-300.

WALKER, R. J. & A. HEDGES. 1967. The effect of cholinergic
antagonists on the response to acetylcholine, acetyl-@-meth-
ylcholine and nicotine of neurones of Helix aspersa. Comp.
Biochem. Physiol. 23:977-989.

YESCOTT, R. E. & E. L. HANSEN. 1976. Effect of manganese
on Biomphalaria glabrata infected with Schistosoma manson.
J. Invert. Path. 28:315-320.

The Veliger 27(3):336-338 (January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

Two New Northeastern Pacific Gastropods of the

Families Lepetidae and Seguenziidae

JAMES H. McLEAN

Los Angeles County Museum of Natural History, 900 Exposition Boulevard,
Los Angeles, California 90007

Abstract. "Two new deep water gastropods from the northeastern Pacific are described. In the family
Lepetidae, Jothia lindbergi, broadly distributed at continental shelf depths, Vancouver Island, British
Columbia, to Cabo San Quintin, Baja California; and in the Seguenziidae, Seguenzia quinni, from

abyssal depths off Oregon.

INTRODUCTION

Two SPECIES ARE described below, preliminary to inclu-
sion in an account of the archaeogastropods of the north-
eastern Pacific from Alaska to Baja California. In that
work the rhipidoglossate species are to be treated by
McLean and the docoglossate species by Lindberg.

Type material is placed in the Los Angeles County
Museum of Natural History (LACM), the National Mu-
seum of Natural History, Washington, D.C. (USNM),
the California Academy of Sciences, San Francisco (CAS),
and the National Museum of Canada, Ottawa (NMC).

Family LEPETIDAE Dall, 1869
Genus Jothia Gray, 1850
lothia indbergi McLean, spec. nov.
(Figure 1)

“Lepeta caecoides Carpenter,’ SMITH, 1963:160.
“Lepeta Uothia) fulvua (Miller),” MCLEAN, 1966:126, pl. 4,
figs. 17-21.

Description: Shell (Figure 1) medium sized for genus
(maximum length 6.2 mm), thin, translucent white; an-
terior slope concave to straight; posterior slope convex.
Apex one-fourth shell length from anterior margin, erod-
ed in mature specimens; protoconch retained in specimens
under 2 mm in length, narrow, erect, non-spiral, poste-
riorly projecting. Fine concentric growth lines evident in
shells under 2 mm long. Radial sculpture of 25 to 35
irregularly spaced ribs of unequal strength; rib interspaces
broad, up to 5 times width of ribs; ribs imbricate, pustu-
lose; pustules broader than high; concentric growth irreg-

ularities showing in interspaces. Interior glossy, muscle
scar faintly marked.

Dimensions: Length 6.2, width 4.8, height 2.1 mm (ho-
lotype). The holotype is the largest specimen examined.

Type locality: 183 m (approximately 100 fm) on granite
boulders, 6 miles (9.6 km) W of Point Pinos, Monterey
Co., California (36°39'N, 122°01'W).

Type material: 6 specimens from the type locality dredged
by James H. McLean, R/V Tage (Hopkins Marine Lab-
oratory): holotype and one paratype, 17 November 1960;
4 additional paratypes, 2 March 1961. Holotype LACM
2063, 2 paratypes LACM 2064, 1 paratype CAS 050118,
1 paratype USNM 784749, 1 paratype NMC 86715.

Referred material: 17 lots of this species are represented
in the LACM collection, ranging from the north end of
Graham Island, Queen Charlotte Islands, British Colum-
bia, to Islas San Benito, Baja California, dredged on rocks
in depths from 90 to 300 m. Intermediate localities in-
clude—British Columbia: off the north end of Vancouver
Island; Washington: off Cape Flattery; California: off
Davenport, Santa Cruz County; off Santa Rosa Island;
off Catalina Island; off Cortez Bank; Baja California: off
Cabo San Quintin. There is a single LACM record taken
by scuba diving: one dead shell in rubble at 51 m on
Cordell Bank, Marin County (37°59.1'N, 123°25.5'W),
Robert W. Schmieder, 8 October 1983.

Comparisons: Jothia lindbergi is smaller-shelled and lacks
the reddish orange coloration of the northeastern Atlantic
I. fulva (Miller, 1776).

Remarks: Earlier (MCLEAN, 1966) I could not find suf-

_ J. H. McLean, 1985

Page 337

Explanation of Figures 1 and 2

Figure 1. Jothia lindbergi McLean, spec. nov. Exterior and interior (anterior at top), and lateral (left side) views

of holotype. Length 6.2 mm.

Figure 2. Seguenzia quinni McLean, spec. nov. Apertural and basal views of holotype. Height 7.6 mm.

ficient grounds to separate the new species from Jothia
fulva in the northeastern Atlantic. However, the north-
eastern Pacific species is now known from a sufficient
number of lots to show that it never has a trace of the
red-orange coloration usual in J. fulva and does not reach
the size known for J. fulva. (The largest examined speci-
men of J. fulva is 8.2 mm in length; LACM, Gullmar
Fjord, Sweden.) In view of these differences, and the greatly
disjunct distribution, with no records of the genus in Alas-
ka or the North American Arctic Ocean, a separate name
for the northeastern Pacific species is warranted. No rad-
ular differences between the two species were detected,
the radula being more useful as a generic than specific
character in this genus.

Etymology: The name honors David R. Lindberg, of the
University of California, Berkeley.

Family SEGUENZIIDAE Verrill, 1884

Genus Seguenzia Jeffreys, 1876

Seguenzia quinnt McLean, spec. nov.
(Figure 2)

Description: Shell large for genus, up to 7.6 mm in height,
higher than broad, narrowly umbilicate, thin, translucent
white; interior and exterior surfaces with pink and green
iridescence. Protoconch and first teleoconch whorl missing
in the two known specimens. Remaining teleoconch whorls
6, evenly expanding. Primary spiral sculpture of three
narrow, projecting keels—subsutural keel, which covers
peripheral keel of preceding whorl, shoulder keel, and
peripheral keel. Area between subsutural keel and shoul-
der keel concave at first, becoming slightly convex on final
whorl; area between shoulder keel and peripheral keel
concave at first, becoming straight on final whorl. Base
evenly convex, with 10 spiral cords; those closest to pe-
ripheral keel and umbilicus more broadly spaced than
other basal cords. Secondary sculpture of numerous, sharp,
evenly spaced collabral riblets, and finer, microscopic, spi-
ral threads. Collabral riblets traversing primary spiral

Page 338

The Veliger, Vol Z/-Nors

cords, forming fine, sharp nodes. Spiral threads present
on spire and on base, except near umbilicus; spiral threads
traversing axial riblets. Umbilicus narrow, bordered by
projecting keel, faintly traversed by axial riblets. Outer
lip thin, posterior sinus deep, bordering lip flared in ma-
ture stage. Parietal glaze thick enough to obliterate sec-
ondary sculpture but not primary spirals of base. Inner
lip moderately thick, flared over umbilicus, strongly flexed
at base to form strong columellar spur. Lip flared to left
(in apertural view) anterior to columellar spur; lip also
flaring to produce broad anterior canal.

Dimensions: Height 7.6, diameter 6.0 mm (holotype);
height 7.3, diameter 5.9 mm (paratype).

Type locality: 3900 m, Tufts Abyssal Plain, 452 miles
(723 km) W of Cape Foulweather, Lincoln Co., Oregon
(45°02.0'N, 134°42.2'W).

Type material: One specimen from type locality, collected
by the R/V Yaquina, Oregon State Univ. sta. BMT 306,
9 October 1972. Holotype LACM 2065. 1 paratype
USNM 784750, from 2826 m, Cascadia Abyssal Plain,
144 miles (230 km) W of Cape Foulweather, Lincoln Co.,
Oregon (44°53.5’N, 127°27.5'W), collected by the R/V
Cayuse, Oregon State Univ. sta. BMT 332, 4 November
1973.

Both specimens are now preserved dry; deeply retracted
soft parts are visible through the translucent shell. Except
for the slight difference in size, the two specimens are
identical; both have 10 basal cords.

Referred material: Known only from the holotype and
single paratype.

Comparisons: This is the only eastern Pacific Seguenzia
to have strongly flaring borders to the anterior and pos-
terior canals and to have a pronounced development of
the columellar spur. Compared to other eastern Pacific
species, $. quinni has spiral and axial sculpture like that
of S. stephanica Dall, 1908, but that species is not umbil-
icate and lacks the strongly flaring anterior and posterior
canals. The umbilicus and flared aperture of Seguenzia
quinni resembles that of “Seguenzia n. sp.,” from the
Philippines (QUINN, 1983b, fig. 1), which differs in hav-
ing a more acute spire angle and fewer spiral cords on the
base. Seguenzia textilis MARSHALL (1983:242, figs. 3F-I),
from the Tasman Basin, is smaller and has less pro-
nounced axial riblets.

Remarks: Three other seguenziids (Seguenzia stephanica

Dall, 1908, S. megaloconcha Rokop, 1972, and the recently
described Carenzia inermis Quinn, 1983) are also known
at abyssal depths on the Cascadia Abyssal Plain off Or-
egon (LACM). However, none of these species is repre-
sented in material taken from the Tufts Abyssal Plain
(type locality of S$. quimni), west of the Juan de Fuca
Ridge and the Blanco Fracture Zone. Infaunal biomass is
richer on the Cascadia Plain (GRIGGs et al., 1969; CAREY,
1981).

Etymology: Named after James F. Quinn, Jr., of the
State of Florida Department of Natural Resources, St.
Petersburg, who has recently reviewed the genera of the
superfamily Seguenziacea.

ACKNOWLEDGMENTS

I thank Eugene Coan, Carole S. Hickman, and David R.
Lindberg for reviewing the manuscript.

LITERATURE CITED

Carey, A. G., JR. 1981. A comparison of benthic infaunal
abundance on two abyssal plains in the northeast Pacific
Ocean. Deep-Sea Res. 28A(5):467-479.

Da.LL, W. H. 1908. Reports on the dredging operations off the
west coast of Central America to the Galapagos, to the west
coast of Mexico, and in the Gulf of California .... XIV.
The Mollusca and Brachiopoda. Bull. Mus. Comp. Zool.,
Harvard 43:205-487, pls. 1-22.

Griccs, G. B., A. G. CarEy, JR. & L. D. KuLM. 1969. Deep-
sea sedimentation and sediment-fauna interaction in Cas-
cadia Channel and on Cascadia Abyssal Plain. Deep-Sea
Res. 16:157-170.

MarsHALL, B. A. 1983. Recent and Tertiary Seguenziidae
(Mollusca: Gastropoda) from the New Zealand region. New
Zealand J. Zool. 10: 235-262.

McLEan, J. H. 1966. West America prosobranch Gastropoda:
superfamilies Patellacea, Pleurotomariacea, and Fissurel-
lacea. Doctoral Thesis, Stanford University. x + 255 pp., 7
pls.

QuINN, J. F. 1983a. Carenzia, a new genus of Seguenziacea
(Gastropoda: Prosobranchia) with the description of a new
species. Proc. Biol. Soc. Wash. 96(3):355-364.

Quinn, J. F. 1983b. A revision of the Seguenziacea Verrill,
1884 (Gastropoda: Prosobranchia). I. Summary and eval-
uation of the superfamily. Proc. Biol. Soc. Wash. 96(4):725-
757.

Roxop, F. J. 1972. Notes on abyssal gastropods of the eastern
Pacific, with descriptions of three new species. Veliger 15(1):
15-19.

SmiTH, A. G. 1963. Two range extensions. Veliger 5(4):160-
161.

The Veliger 27(3):339-346 (January 2, 1985)

THE VELIGER
© CMS, Inc., 1985

NOTES, INFORMATION & NEWS

Soviet Contributions to Malacology in 1979
by
MORRIS K. JACOBSON
AND
KENNETH J. BOSS
Museum of Comparative Zoology,
Harvard University,
Cambridge, Massachusetts 02138

INTRODUCTION

We herein continue to list, as we have in past years, the
Russian malacological papers abstracted in the 1979 Re-
ferativnyy Zhurnal (see Veliger 22(4):392 for the last list-
ing and reference to previous ones). The delay in produc-
ing this bibliographic service was occasioned by the
reluctance of the junior author to carry on after the un-
anticipated death of the senior author; however, a number
of colleagues remarked on the utility of this list. Further,
it would seem wise to attempt to keep abreast of some of
the advances proposed in the Russian malacological lit-
erature. Often there are revolutionary revisionary works
that completely alter the usually accepted taxonomic
schemes and sometimes they follow quickly on the heels
of those only previously proposed by Soviet researchers;
this year proves no exception!

We have generally followed the categorical arrange-
ment as utilized in the Referativnyy Zhurnal; however,
we have not included the titles of abstracts of malacolog-
ical papers published as part of the XIV Pacific Science
Congress because these have been recently reviewed by
LINDBERG (1984. Veliger 26(4):334).

Among the works listed this year, three are of particular
importance and we provide somewhat more detailed ab-
stracts for them: Shileiko’s review of the systematics and
classification of the terrestrial pulmonates (Geophila);
Skarlato & Starobogatov’s re-study of the classification of
the Bivalvia in which once again we see several modifi-
cations and alterations in previous systems, especially in
the establishment of new higher taxa and the elevation of
previous taxa to higher rank; and finally, Minichev &
Starobogatov’s reclassification of the Class Gastropoda,
which is subdivided by them into eight subclasses. The
first two of the papers will appear in edited English trans-
lations in Special Occasional Publications published by
the Mollusk Department, Museum of Comparative Zo-
ology, Harvard University, Cambridge, MA 02138.

Several other noteworthy contributions deserve men-
tion: Sirenko’s review of the Leptochitonidae, Lus’ de-
scription of new taxa in the buccinids, and Moskalev’s

review of the Lepetellidae, which has been translated
through the auspices of C. S. Hickman, University of
California-Berkeley, Department of Paleontology, Berke-
ley, GA 94720.

Important papers on the biology of squids, especially
the ommastrephids, appeared by Nesis, Nigmatullin, and
their colleagues.

Likharev & Viktor, acknowledged experts on terrestrial
slugs, have studied the parallelisms and convergences in
the evolution of the slug condition in different phyletic
lineages. Zharkova also noted convergent loss of photo-
sensitive organs and vision in deeper water marine gas-
tropods.

Utilizing electrophoretic analyses, Logvinenko & Ko-
dolova show the genetic distinctness of the margaritiferids
from the unionids (Unio and Anodonta); a translation of
this paper has been prepared through the efforts of Mr.
Doug Smith, University of Massachusetts, Amherst, MA
01002. Another work involving electrophoretic techniques
is that of Nikiforov who showed that what was considered
by some as three separate species of oysters in the western
Pacific is in fact only a single species.

Dr. Robert Robertson of the Academy of Natural Sci-
ences of Philadelphia helped us to obtain an issue of the
Referativnyy Zhurnal that was missing in the MCZ Li-
brary. Mrs. Robert Britz carefully typed the manuscript.

Abbreviations and acronyms we have used are:

2SC—2nd Vses. konf. po biol. shel’fa, Sevastopol. (Second all
Union conference on the biology of [continental] shelves, Se-
vastopol).

BMV—Biologiya Morya (Marine Biology, Vladivostok).

ES—English summary.

GZ—Gidrobiologicheskii Zhurnal (Hydrobiological Journal).

NDVS—Nauch. Dokl. Vyssh. Shkol. Biol. Nauk. (Scientific Re-
ports of the Higher Educational School for Biological Sci-
ences).

PDM—Promysl. dvustvorchat. mollyuski-midii i ikh rol’ v eko-
sistemakh, Leningrad. (Commercial bivalve molluscan mus-
sels and their role in the ecosystem, Leningrad).

SRF—Nauch. Soobshch. Inst. Biol. Morya. Dal’nevost. Nauch.
Tsentr. (Scientific Reports of the Institute of Marine Biology.
Far Eastern Scientific Center. Acad. Sci. USSR).

TIO—Trudy Instituta Okeanologii. Akademiya Nauk SSSR.
(Transactions of the Institute of Oceanology, Academy of Sci-
ences, USSR).

TZI—Trudy Zoologicheskogo Instituta. (Transactions of the
Zoological Institute of the Academy of Sciences of the USSR,
Leningrad).

ZEBF—Zhurnal Evolyutsionnoi biokhimii i fiziologii. (Journal
of evolutionary biochemistry and physiology).

ZOB—Zhurnal Obshchey Biologii. (Journal of General Biolo-

By).
ZZ—Zoologicheskii Zhurnal. (Zoological Journal).

Page 340

GENERAL

BELYAKOVA, Yu. V. 1979. On the molluscan fauna of Central
Kazakhstan. Fauna ekol. i zoogeog. gel’mintov zhivot. Ka-
zakhstana (The fauna, ecology and zoogeography of helminth
animals of Kazakhstan). Inst. zool. Akad. Nauk KazSSR, Alma
Ata. 1978, pp. 44-45.

[In this region, related to the Volga-Ural and Irtysh provinces

of the Euro-Siberian Palearctic subregion, 58 species of fresh-

water mollusks are known.]

Bercer, V. YA. 1979. The functional morphological basis of
euryhalinity in marine mollusks. ZOB 40(1):93-103(ES).
[The problem of various mechanisms of osmotic tolerance and
resistance to changes in salinity in marine mollusks is discussed. ]

BerGER, V. YA., N. M. KovaLeva, O. Yu. MIKHAILOVA, YU.
V. NATOCHIN & V. V. KHLEBOVICH. 1979. The influence of
inhibitors on the ionic contents and size of muscle cells in
marine mollusks. BMV, no. 4, pp. 47-53.

[Physiological experiments with Mytilus edulis and Littorina lit-

torea showed variant effectiveness of sodium uptake by different

chemicals. |

GorOKHovy, V. V. & V. S. OsETROV. 1978. Molluscocides and
their application in rural industry. Kolos: Moscow. 224 pp.
[Designed for the use of agronomists and veterinarians, this book
describes the method of application of special chemicals and their

effect on the fauna and flora.]

KHOKHUTKIN, I. M., S. V. SHUTOV & V. N. OL’SHVANG. 1978.
A more precise determination of the (zoogeographical) regions
of continental mollusks in connection with a study on the bi-
ology of birds. Fauna, ekol. i izmenchivost’ Zhivotnykh (Fau-
na, ecology and variability of animals), Sverdlovsk, p. 10.

LIKHAREV, I. M. 1979. Mollusks: fundamental results of their
investigation. 6th All Union Meeting for the study of mollusks.
Leningrad, 7-9 Feb. 1979. Leningrad. Nauka (Science Press),
263 pp.

LUKIN, A. K. 1979. On the freshwater molluscan fauna of the
fluviatile waters of the Saratov Region. Trudi Saratov. nauch.
Vet. St. 13:51-56.

NaTOCHIN, Yu. V. & V. YA. BERGER. 1979. Ionic composition
of molluscan cells: evolutionary and ecological aspects. ZEBF
15(3):295-302(ES).

[Despite sharp changes in intracellular sodium as cells adjust to

various ambient salinities, intracellular potassium concentrations

remain essentially constant.]

NIsTRATOVA, S. N. 1979. On the change of cardiac sensitivity
to acetylcholine during spawning in marine mollusks. ZEBF
15(5):508-512(ES).

[A correlation between the sensitivity of cardiac muscles to ace-

tylcholine and the state of the reproductive system was discovered

in 5 species of marine mollusks. It is shown that during the
secretion of ripe sexual products, there is a considerable increase
of sensitivity to the mediator acetylcholine from a threshold con-
centration of normally 10~° to 10~' or 107’ molar at spawning. |

STADNICHENKO, A. P. 1979. Survey of Crimean freshwater mol-
lusks. Vestnik zoologii, no. 1, pp. 14-19.

[35 species of gastropods and bivalves occur, of diverse geograph-

ical affinities, but Palearctic and Euro-Siberian species predom-

inate. |

APLACOPHORA

Ivanov, D. L. 1979. The structure and functional morphology

The Veliger; Vol. 27-3Now3

of Chaetoderma (Mollusca, Caudofoveata) radular apparatus.
ZZ 58(9):1302-1306(ES).
[A new terminology for the parts of the radula of Chaetoderma
is proposed, based primarily on function. A critical analysis of
the views of various students of the structure, provenience, and
evolution of the radular apparatus is provided.]

POLY PLACOPHORA

SIRENKO, B. I. 1979. On the composition of the Leptochitonidae
Dall 1889 (=Lepidopleuridae Pilsbry 1892) (Polyplacophora)
and description of a new bathyal species. TZI 80:116-121.

[The status of Leptochiton, Lepidopleurus, Deshayesiella, Hanley-

ella, and Oldroydia is reviewed. The first four taxa are genera of

this family and a diagnosis of each is offered. Oldroydia is a

subgenus of Deshayesiella. Most chiton species lacking an inser-

tion plate should be in Leptochiton. Leptochiton batialis from 1450-

2500 m near the southern Kurile Islands and Japan is described

as new. |

GASTROPODA, GENERAL

ALYAKRINSKAYA, I. O. 1979. On the mobilization of calcareous
compounds in the shells of some gastropods. ZZ 58(5):648-
654(ES).

[The quantity of calcium in the hemolymphs is increased in

Viviparus viviparus in drought conditions and in Helix pomatia

during hibernation and aestivation as well as at the time of egg

laying. This promotes the buffering capacity of the hemolymph,
which is essential under conditions of difficult extremes. ]

MINICHEV, YU. S. & Ya. I. STAROBOGATOV. 1979. Gastropod
subclasses and their phylogenetic relationships. ZZ 58(3):293-
305(ES).

[It is proposed to divide the class Gastropoda into 8 subclasses:

Cyclobranchia (as outlined by GOLIKOV & STAROBOGATOV, 1975);

Scutibranchia (as outlined by the same authors but with the

addition of Loxonematoidea and the removal of Macluritidae,

Ecculiomphalidae, and Onychochilidae); Pectinibranchia (as

outlined by the same authors but with the exclusion of Pyram-

idellimorpha); Divasibranchia (Siphonariidae and Macluritida
with families Macluritidae, Ecculiomphalidae, and Pelagielli-

dae); Dextrobranchia (as of MINICHEV & STAROBOGATOV, 1975,

but with the addition of Order Onychochilidia, a new order with

the single family Onychochilidae); Pulmonata (in its usual ex-
tent, but with the addition of Subulitoidea and Vellainellidae
but without Siphonariidae, Onchidiidae s. /ato, Rhodopidae, and

Soleolifera); Opisthobranchia (as of MINICHEV & STAROBOGA-

TOV, 1975, but excluding Ringiculidae) and Sinistrobranchia,

new subclass, which consists of 3 superorders and 5 orders: Su-

perorder Architectonicoida with order Architectonicida (super-
family Architectonicoidea, Mathildoidea, Nerineoidea) and or-
der Epitoniida (superfamily Epitonioidea, Janthinoidea);
superorder Melanelloida with order Melanellida (superfamily

Pseudomelanioidea, Trochaclidoidea, Aclidoidea, Melanelloi-

dea); superorder Pyramidelloida with orders Ringiculida (family

Ringiculidae) and Pyramidellida (superfamily Pyramidelloi-

dea). The diagnosis of each subclass is provided, the evolutionary

processes leading to ther characteristic features are discussed
together with their phylogenetic relationships.]

Soxo.tov, V. A. & V. A. KovaLev. 1979. The sensory system
of gastropod statocysts. Sensor. sistemi 1 mekhanizmi zreniya.
Nov. metodi issled. (Sensory system and the mechanics of vi-
sion. New investigative methods). Leningrad. pp. 136-148.

[SEM and electrophysiological data permit an analysis of how

statocysts detect the gravitational field.]

Notes, Information & News

GASTROPODA, PROSOBRANCHIA

ARAKELOVA, E. S. 1979. The influence of temperature and size
on the metabolic rate in Melanopsis praemora L. (Pectinibran-
chia). Eksperim. i polev. issled. biol. osnov. produktivn. ozer.
(Experimental and field studies of the basic biological pro-
ductivity in lakes.) Leningrad. pp. 169-180.

[Rate doubles with 10° increases (between 10° to 27°C.]

BERGER, V. YA. 1978. A study of salinity adaptations in Littorina
sitchana, with special reference to the evolution of the genus
Littorina. ZZ 57(12):1786-1789(ES).

[Littorina sitchana has a high salinity tolerance but low resistance

to freshwaters. The penetration of the genus into brackish water

habitats in the north Atlantic was facilitated by the high osmotic
tolerance of the ancestral Pacific form.]

BERGER, V. YA. 1978. Euryhalinity and the evolution of Litto-
rina. Morfol. sistematika i evolyutsiya zhivotnikh, Leningrad.
pp. 46-47.

[Littorina sitchana, L. kurila, and L. squalida of the Pacific show

the greatest tolerance for low salinity. They are close to the

ancestral forms from which derived the Atlantic species, L. sax-

atilis, L. obtusata, and L. littorea. Littorina mandshurica and L.

brevicula have a much lower osmotic tolerance. It is assumed the

evolution of these two groups took place relatively independent-
ly.]

BERGER, V. YA. & A. N. Kuz’MIn. 1978. The influence of low-
ered salinity on the development of some White Sea mollusks.
ZZ 57(11):1632-1636(ES).

[Minimum normal salinities were found to be 17-18%0 for Lit-

torina obtusata and 15%0o for Littorina littorea, L. saxatilis, Epheria

vincta and Margarites helicinus; lower salinities halt development
and ultimately destroy embryos and larvae.]

GALKIN, Yu. I. 1978. The influence of climatic variation on the
distribution of archaeogastropods in the Barents Sea. Morfol.
sistematika i evolyutsiya zhivotnykh. Leningrad. pp. 7-9.

GALKIN, Yu. I. & L. I. MOSKALEv. 1979. On the differences
between 2 related species of prosobranch gastropods Tectura
virginea (Muller, 1776) and Problemacmea rubella (Fabricius,
1780) (Gastropoda, Tecturidae). TZI 80:102-107.

[Differing in conchological features, mode of reproduction and

geographic distribution, the species are most easily distinguished,

despite their very similar radulae, by the presence or absence of

a dark border along the inner aperture of the shell.]

GuL’BIN, V. V. 1978. Prosobranch gastropods of the littoral of
the northwestern part of the Sea of Japan. 2SC, pp. 30-31.

GuL’BIN, V. V. 1978. The species and ecology of the Docoglossa
of the Kurile Island shelf. SRF, no. 3, pp. 32-34.

[Vertical and substrate distribution as well as feeding and re-

productive biology are examined. ]

GUL’BIN, V. V. 1979. A new gastropod species from the littoral

of Far Eastern Seas. BMV, no. 3, pp. 88-89(ES).
LJeffreysina golikova n. sp. (Rissoellidae) figured (radula and
shell).]

KaraBEILI, O. Z. 1978. Gastropods of the section Eurycaspia
(genus Turricaspia, family Pyrgulidae) of the Caspian Sea.
Dokl. MOIP. Zool. i botanika. Otd. Mosk. o-va. ispyt. pri-
rodi. Moscow. pp. 30-32.

LUKANIN, V. V. 1978. Peculiarities of the reaction of Littorina
to various combinations of temperature and salinity. ZZ 57
(9):1319-1323(ES).

[White Sea populations of Littorina obtusata, L. littorea, and L.

saxatilis were studied and it was shown that temperature and

salinity regimes uncharacteristic of the White Sea, even though

Page 341

they fell within the tolerance ranges of the species, were dele-
terious. |

Lus, V. YA. 1978. A new abyssal buccinid species and some
features of the morphology and anatomy of deep-water Pacific
Buccinum. TIO 113:157-165(ES).

[Buccinum crebricarinatum from 3669 m in the Bering Sea is

described, a maximum depth for buccinids. Anatomical remarks

on other deep-water buccinids such as Tacizta and Calliloncha
compare these deep-water taxa with the sublittoral type-species

B. undatum L.]

Lus, V. YA. 1978. A new genus and species of Buccinidae from
abyssal depths of the Idzu-Bonin Trench in the Pacific. TIO
113:147-156(ES).

[Calliloncha solida is described from the Idzu-Bonin Trench in

depths of 6770-6850 m. Particulars of its shell, operculum, and

gross anatomy are provided along with a discussion of buccinids
in the abyssal and lower abyssal zone of the trenches of the

Pacific Ocean. |}

MosKALev, L. J. 1978. Lepetellidae (Gastropoda, Prosobran-
chia) and related mollusks with similar shapes. TIO 113:132-
146(ES).

[Lepetellidae Dall, 1882, Addisoniidae Dall, 1882, Cocculinel-

lidae Moskalev, 1971, and Bathyphytophilidae new family are

examined. Their species composition and systematic placement
among the pectinibranch gastropods are considered. The type-
genus of the Bathyphytophilidae is the newly introduced, mono-

typic Bathyphytophilus caribaeus which inhabits depths of 2450-

6780 m in the Caribbean region of the Atlantic Ocean and uti-

lizes as food and substrate the rhizomes and possibly also the

leaves of Thalassia testudinum which sink to abyssal and ultra-
abyssal depths from shallow water. Another genus in this family
is also newly introduced and monotypic: Aenigmabonus kurilo-

kamtschaticus which lives in depths of 6120-8160 m.]

MoskvICHEVA, I. M. 1979. On the systematics of the Vivipari-
dae of Far Eastern USSR. TZI 80:87-92.

[6 species of viviparids occur in the Amur River basin, 2 of which

are described as new: Cipangopaludina zejaensis and C. sujfunen-

sis. The new genus Amuropaludina is established with Paludina

praerosa Gerstfeldt, 1859, as type-species by original designa-

tion. ]

NakHomov, A. N., E. V. Kuz’MIN & M. V. KRIVOBOKOV. 1978.
An analysis of the isosyme esterase in the adaptation of Lit-
torina littorea to a decrease of salinity in its surroundings. Mor-
fol. sistematika 1 evolyutsiya zhivotnikh, Leningrad. pp. 73-
1S:

SLAVOSHEVSKAYA, L. V. 1979. The organization, reproduction,
and the systematic position of “Thapsiella” plicosa (Smith)
(Rissooidea) from the Sea of Japan. TZI 80:93-101.

[A comparison of Thapsiella plicosa with both Onoba semicostata

(the type-species) and O. semistriata shows that plicosa belongs

to the Onobidae. It is assumed that plicosa is closer to the far

eastern Onoba than to the Mediterranean Thapsiella. Thapsiella
and the far eastern Onoba appear to be distinct in shell structure,

a feature testifying to the heterogeneity of this group. Until a

revision of this group is undertaken, it may be advisable to pre-

serve plicosa provisionally as “Thapsiella.’’|

STADNICHENKO, A. P. 1978. Comparative characteristics of the
albumen spectra of the embryonic capsules and hemolymph of
the Viviparidae. Vestnik zoologii, no. 5, pp. 91-94.

[Electrophoretic analysis revealed 7 fractions in adults of Vivip-

arus contectus while capsule fluid showed a characteristic differ-

ent albumen and absence of one of the adult fractions. |

ZHARKOVA, I. S. 1978. On rudimentary eyes of the low-abyssal

Page 342

species Tacita holoserica (Prosobranchia, Buccinidae). TIO 113:
166-168(ES).

[In Tacita holoserica from 6090-6135 m, as in many deep water

gastropods, vision is reduced or lacking. Histological sections

disclosed rudiments of eyes which are decidedly reduced, of small
size, not deeply buried in connective tissue, and lack pigmenta-
tion.]

ZHARKOVA, I. S. 1978. Reduction of the organs of sight in some
representatives of the order Diotocardia (Gastropoda: Proso-
branchia). ZZ 57(11):1637-1640(ES).

[A positive correlation was documented between reduced vision

as noted histologically and increased depth from the littoral to

the ultra-abyssal. Species investigated were the littoral patellid

Patella piperata, the lepetids Cryptobranchia concentrica from 23

m and Lepetella tubicola, and the cocculinids Tentaoculus perlu-

cida from 300-450 m, Caymanabyssa spina from 6740-6780 m,

and Fedikovella caymanensis from 6800 m.]

GASTROPODA, PULMONATA, AQUATIC

GUNDRIZER, V. A. & Ya. I. STAROBOGATOV. 1979. New species
of freshwater mollusks of the Lower Yenisei basin. ZZ 58(8):
1130-1135(ES).

[New members of Lymnaea (Peregriana) include L. kurejkae and

L. dolgini, which form a special species group; L. igarkae belongs

to the group of L. ovata, and L. dipkunensis to the group of L.

mucronata. Diagnostic features of the shell and reproductive sys-

tems are delineated.]

Kruc.ov, N. D. & G. V. BEREZKINA. 1978. Some questions on
the physiology of reproduction in Lymnaeida. NDVS 11:49-
53. [Four different modes of copulation are described; addi-

tionally the role of the spermatheca in the absorption of surplus

allosperm is documented. ]

LOGVINENKO, B. M., S. M. GERMAN & O. P. Kopo.ova. 1979.
A study of the seasonal changes in the esterase system and
shell morphology of Lymnaea stagnalis. ZZ 58(9):1307-
1312(ES).

[In populations of the pond snail, morphological features of the

shell are more variable than certain characteristics, namely those

of particular protein-enzyme relationships as determined elec-
trophoretically. ]

Potapina, N. V. 1978. On the origin of the cells which form
capsules around alien bodies in Lymnaea stagnalis L. Onto-
genez 9(6):639-642(ES).

[Autoradiographic analyses showed cells originating in the blood. ]

ZATRAVKIN, M. N. 1979. Variability of the common pond snail
Lymnaea stagnalis from two natural populations. ZZ 58(8):
1230-1233(ES).

[One population from shallow waters of the Bay of Bolshoye
Miassova was contrasted to another from the II’minsk River,
both in the Il’minsk Preserve. The water in the bay partially
dries up in summer and freezes to the bottom in winter; hence
its snail population lives under very rigorous conditions. There
is a distinct difference in the shells of the different populations
and this difference was shown to be due to resistance to the
effects of gamma rays at gastrulation: the bay form, which was
shown to be more resistant, is characterized by smaller dimen-
sions and a taller shell with a narrow aperture.]

GASTROPODA, PULMONATA, TERRESTRIAL

AL’MUKHAMBETOVA, S. K. 1979. New species of Pupilloidea
(Mollusca; Gastropoda) from the Zailiisk Alatay. Izv. (Akad.
Nauk) KazSSR. (News of the Acad. Sci. Kazakh SSR) Ser.
Biol. (1979). No. 3, 30-33 (Kazakh Summary).

The Veliger, Voll 274 Norms

[3 new species described. ]

ARUTYUNOVA, L. D. 1978. On the annual cycle of Deroceras
caucasicum and Vitrinoides monticola (Limacidae) under labo-
ratory conditions. Bio. zh. Armenii (Armenian Journal of Bi-
ology) 31(9):990-992.

[Both species lived for 2 years on a diet of cabbage, carrots, and
potatoes; V. monticola had 1 generation a year, and egg laying
took place in 8.5-9.5 months, with time of incubation 1.5-3.5
months; the species overwinters in the egg stage. Deroceras cau-
casicum has 4 generations a year with egg laying beginning at
the age of 2 months; incubation was up to 1 month.]

Dmitrieva, E. F. 1978. “Critical” periods in the ontogenesis of
Deroceras reticulatum in connection with bio-climatic condi-
tions of the Leningrad district. Nauch. tr. Leningr. s.-kh. in-
ta (Scientific works of the Leningrad institute) 351:62-64.

Ivanov, V. A. 1978. The slug fauna of the northern slopes of
the Central Caucasus. Ekol. zhivotnykh sev. sklonov Tsentr.
Kavkaza (Ecology of animals from the northern slopes of Cen-
tral Caucasus), Ordzhonkidze. pp. 92-94.

[Pseudomilax orientalis and Arion subfuscus are newly recorded

from the region.]

KHOKHUTKIN, I. M. & A. I. LAZAREvA. 1978. Polymorphism in
a population of terrestrial pulmonates. Fiziol. 1 populyatsion.
ecol. zhivotnykh (Physiological and population ecology of an-
imals), Saratov, no. 5/7, pp. 148-150.

[In 1965 the populations of 8 species (over 20,000 samples) of

Helicoidea, mainly Bradybaena fruticum, were examined: poly-

morphism appeared principally in shell coloration with 2 phe-

notypes. |

KHOKHUTKIN, I. M. & A. I. LAZAREvaA. 1979. Changes in growth
and structure in a population of Bradybaena. Trudi Inst. Ekol.
Rast. i Zhivotnikh. Uralsk. nauch. tsentra (Works of the In-
stitute on the ecology and distribution of animals. Ural Sci-
entific Center), Acad. Sci. USSR, no. 1, pp. 107-122.

[Bradybaena fruticum and B. lantzi basically are annuals with

few individuals surviving beyond one year.]

KovaLeEv, V. A. 1979. Responses of the statocysts of Helix vul-
garis to vibrational stimulation. ZEBF 15:94-95.

[Results demonstrated the ability of the statocyst to react to fluc-

tuations of the substrate within a range of 30-1000 Hz.]

LIKHAREV, I. M. & A. I. Viktor. 1979. Structural parallelisms
and the systematic position of slugs in the suborder Stylom-
matophora. TZI 80:70-86.

[Slug-like representatives of the superfamilies Arionoidea (Phi-

lomycidae, Arionidae), Zonotoidea (Parmacellidae, Milacidae)

Limacoidea (Agriolimacidae, Limacidae and Boettgerillidae) and

Trinonochlamydoidea (Trigonochlamydidae) are discussed. ]

LivsHitz, G. M. & A. A. SHILEIKO. 1978. The life cycle of
Brephulopsis bidens. Ekologiya 5:77-83.

[Although the maximum life span is 2.5 years, not more than

one-third of the population attains this age with the remainder

dying by 1.5 years. The pre-reproductive age lasts about 1 year
and mating occurs from April to May, with eggs being laid in

May to June. The animals bury themselves a few centimeters

in the soil to hibernate from November to March.]

SHIKOoV, E. V. 1979. The land snail fauna of populated areas of
the Valdai Hills and adjacent territories. ZZ 58(7):966-
976(ES).

[The districts of Kalinin, Novgorod, Pskov, Moscow, and Len-

ingrad were examined. ]

SHILEIKO, A. A. 1979. The systematics of the order Geophila
(=Helicida) (Gastropoda, Pulmonata). TZI 80:44-69.

[A new taxonomic scheme of the Geophila is proposed, based

Notes, Information & News

upon an analysis of the methods and direction of the morpho-
logical development of characteristics of the shell, foot, and ex-
cretory and reproductive systems. The order is divided into 5
suborders: Achatinina new, Oleacinina new, Pupillina new, He-
lixina new, and Limaxina new. Within the suborder Helixina
there are 3 infraorders: Endodontinia new, Helixinia new, and
Zonitinia new. The infraorder Endodontinia is regarded as tran-
sitional to the 2 other infraorders. The Limaxina is divided into
2 infraorders: Trigonochlamydinia new, and Limaxinia new. A
discussion of the systematic position and phylogenetic relation-
ship of the basic subordinate taxa is presented. It is shown that
in the course of evolution the following lines of parallel and
convergent specializations in the development of different organs
and structures took place: (1) The establishment of sigmurethry
entirely in the primitive and secondary urethra. (2) The for-
mation of the aulacopod foot, at times accompanied by the be-
ginning of a tripartite sole. (3) The reduction of the shell and
the development of the slug-like form. (4) The transformation
into predators. ]

UvuieEva, K. K. 1979. The agriculturally harmful slugs of south-
east Kazakhstan. Alma-Ata, Nauka. 59 pp.

[Handbook designed for scientific workers, agronomists, and gar-

deners. |

VALIAKHMEDOV, B. & Z. IZZATULLAEV. 1979. On the distribu-
tion of terrestrial pulmonates in the soils of the vertical zone
of Tadzhikistan. ZZ 58(6):810-815(ES).

[Distribution is determined by soil-climate conditions. ]

ZEIFERT, D. V. 1978. Weight determination of terrestrial mol-
lusks by morphometric indices. Probl. pochv. zool. Minsk. pp.
93-95.

ZEIFERT, D. V. 1978. Experimental measurement of respiration
in terrestrial mollusks. Fauna, ekol. i izmenchivost’ zhivot-
nykh (Fauna, ecology and variability of animals), Sverdlovsk.
pp. 26-27.

GASTROPODA, OPISTHOBRANCHIA

Rocinskaya, T. S. 1978. The first deep-water capture and ex-
tension of range for Coryphella stimpsoni (Verrill) (Gastropo-
da, Nudibranchia). TIO 113:169-177(ES).

[Formerly this species was known only from the northwestern

Atlantic Ocean and the White and Barents seas from the littoral

to 200 m. Based on samples in the Zoological Institute in Len-

ingrad, it was found that the species occurs, in addition to the

Sea of Japan at depths to 3620 m, also in the Okhotsk, Kara,

and Laptev seas. A map showing this distribution is provided

and some aspects of the animal’s reproductive biology are dis-
cussed. |

ZaITSEVA, O. V. 1978. Characteristics of the neuronal compo-
sition of the central nervous system of nudibranch mollusks.
ZEBF 14(5):497-504.

[Coryphella rufibranchialis, Dendronotus arborescens, and Cadlina
laevis of the White Sea were studied in various stages of post-
larval development. The position of the largest neurons was
mapped. For C. rufibranchialis and D. arborescens about 65-78
neurons were noted and a few of their characteristics described
as well as age variations in body size, shape, pigmentation, and
neurosecretory activity. With the help of impregnation with sil-
ver nitrate, 2 types of branching were discovered in the processes
of several neurons. ]

BIVALVIA

ALYAKRINSKAYA, I. O. 1979. Biochemical prerequisites for the
survival of mussels. PDM, pp. 47-48.

Page 343

[Optimum conditions obtain at weak alkalinity levels; with greater
acidity, dissolution of the shell occurs. The muco-ciliary feeding
mechanism is effective against polluted, even petroleum polluted,
waters. |

AVEDEEVA-MARKOvskayYaA, E. B. 1978. On the structure of the
settlement-mass of Modiolus difficillis (Kuroda and Habe).
2 SC, pp. 3-4.
[The most favorable substrate for attachment of Modiolus is sandy
silt at 2-6 m. Here, masses are formed wherein the young attach
themselves to dead and dying individuals and settled larvae are
found among the hairy periostracum. In such a settlement, males
are dominant but not significantly so, and sexually immature
forms constitute 20-30% of individuals.]

DENISENKO, S. G. 1979. Duration of life and growth in the
Iceland Scallop (Chlamys islandica) on the coasts of the Eastern
Murmansk Peninsula. Biol. Probl. Severa 8th Simpoz. (8th
Symposium of the biological problems in the north), Apatity,
pp. 107-108.

Drozpov, A. L. 1979. The ultrastructure of spermatids and
spermatozoids of Crenomytilus grayanus. PDM, pp. 53-54.

Drozpov, A. L. & V. A. KuLikova. 1979. The development of
Crenomytilus grayanus Dunker. Observations on its life cycle.
PDM, pp. 54-56.

[Discussed are the sizes of the eggs, stages of larval development,

formation of prodissoconchs 1 and 2, and the settling of spat.]

Dzyusa, S. M. 1979. Oogenesis and the sexual cycle of Cren-
omytilus grayanus in Peter the Great Bay. PDM, pp. 50-52.
[Spawning takes place in May and August; developmental stages

of gametogenesis in the intervening periods are described. ]

Fro.ova, L. T. 1979. Seasonal changes in the intestinal epithe-

lium of Crenomytilus grayanus. PDM, pp. 122-124.
[Cellular activity is lower during times of low temperatures in
winter and early spring as a correlate of lowered levels of food;
division processes increase during summer but then are reduced
after spawning. |

Goromosova, S. A. & A. Z. SHAPIRO. 1978. Biochemical ad-
aptations of energy exchange in mussels under different en-
vironmental conditions. 2SC, pp. 32-33.

Goromosova, S. A. & V. A. TAMOZHNYAYA. 1979. Transami-
nase activity in the tissues of the mussel (Mytzlus edulis). Biol.
morya (Kiev) 48:70-75(ES).

Goromosova, S. A. & A. Z. SHAPIRO. 1979. Changes in the
activity of the synthesis of glycogen and fructose 1-6-diphos-
phatase in the tissues of Mytilus galloprovincialis; seasonal as-
pects and under hypoxic conditions. PDM, pp. 12-13.

Ivanova, M. B. 1979. On the prevalence and distribution of
Mytilus edulis L. in the littoral of the seas of Far Eastern
USSR. PDM, pp. 58-60.

[Estimates of biomass are given for distinct areas in the north-

eastern Pacific. ]

IzZaTULAEV, Z. 1978. Species composition among large bivalves
[Unionidae] in central Asia. Biol. osnovy ryb. kh-va vodoemov
Sredi Azii i Kazakhstana (The biological basis of the fishing
industry in the waters of Central Asia and Kazakhstan),
Frunze, pp. 65-67.

KaFanov, A. I. 1978. Temperature variability of linear growth
and life duration in 6 species of the subfamily Clinocardiinae
Kafanov 1975 (Mollusca, Cardiidae). ZZ 57(10):1480-
1488(ES).

[Correlations of life span with growth and temperature adhere

to the law of the optimum. ]

KarTAVTSEV, YU. F. 1979. Biochemical methods for the deter-

Page 344

mination of the systematic placement of several mytilids from

the Sea of Japan, and a population-genetic analysis of them.

PDM, pp. 62-64.
[The species studied were Mytilus edulis, M. coruscus, Crenomyt-
ilus grayanus, Modiolus difficilis, Adula falcatoides, Septifer keenae,
Musculista senhousia and (the Black Sea) Mytilus galloprovincialis;
all are readily distinguished electrophoretically. Mytzlus species
are genetically closer than those of other genera and Crenomytilus
is closest to Mytilus. ]

KauFrMan, Z. S. 1978. Temperature dependence for the period
of gamete maturation and spawning of Cvassostrea virginica

Gmelin. GZ 14(4):34-35(ES).

KuristTororova, N. K., N. I. BoGDANOvA & A. N. OBUKHOV.
1979. The contents of several metals in the soft tissues of
Tridacna squamosa in the islands of the Pacific tropics, in con-
nection with the environmental conditions. BMV, no. 3, pp.
67-73(ES).

[Fe, Mn, Cu, Zn, and Pb concentrations in 77idacna correlated

with the geochemistry of particular islands. ]

KosENKo, L. A. 1979. An auto-radiographic study of the male
sexual cells of the coastal scallop (Patinopecten yessoensis).
BMV, no. 3, pp. 44-49(ES).

[Nucleic acid synthesis was high in autumn and correlated with

active reproduction of spermatogonia. |

KRIVOSHEINA, L. V. 1978. Shallow water Pisidiidae (subfamily
Euglesinae) of the upper Irtysh basin. ZZ 57(10):1489-
1500(ES).

[54 species were recognized, of which 10 are in the subfamily

Sphaeriastrinae and 44 in Euglesinae, including 38 Euglesa, 5

Neopisidium and 1 Odhneripisidium; 10 are described as new.

The distribution of these small bivalves is not as extensive as

was previously assumed. ]

KRIVOSHEINA, L. V. 1979. New species of Neopisidium from
eastern Kazakhstan. ZZ 58(4):602-605(ES).

[5 species occur in the basin of the upper Irtysh, 2 of which are

new: Neopisidium altaicum and N. ovatotrigonum.]

Ku.ikova, V. A. 1978. The morphology, seasonal population
dynamics, and settlement of the larvae of Musculista senhousia
in Busse Lagoon [Aniwa Bay] (South Sakhalin). BMV, no. 4,
pp. 61-66(ES).

[Reproduction peaks during the warm summer months; the lar-

vae, abundant components of the plankton, are pelagic for 15-

20 days and their favored settling places are on the alga Ahnfeltia

and Sargassum seaweed. ]

Ku ikova, V. A. 1979. Characteristics of bivalve reproduction
in Busse Lagoon, the Sea of Okhotsk, as affected by water
temperatures. BMV, no. 5, pp. 34-38(ES).

[Despite the peculiar temperature regime of this lagoon in south

Sakhalin Island, the majority of bivalves found there have ad-

justed to a shorter pelagic larval period and spawn at maximum

temperatures. |

LOGVINENKO, B. M. & O. P. KopoLova. 1979. An electropho-
retic comparison of species of Unionacea. Vestnik MGU biol.
(Biological Herald of Moscow State University) 2:65-66(ES).

[Six species of Unionidae (including Anodonta and Unio) and a

single Margaritiferidae were contrasted by disk-electrophoresis. ]

LUKANIN, V. V. 1979. Cellular and organ-level reactions of White
Sea Mytilus edulis to changes in salinity. ZOB 40(5):746-
750(ES).

[Adaptations to lowered salinity are modulated chiefly by the

plasticity of tissues, which is presumably genotypically regulat-

ed; these include respiratory sensitivity and ctenidial stability.]

MAkKSIMOVICH, N. V. 1979. Some features of the reproductive

The Veliger; Vol. 27- ions

cycle of Mytilus edulis in the Chupa Inlet [Kandalakshskaya
Guba] (White Sea). PDM, pp. 84-86.
[Animals mature sexually in 1-2 years and the sex ratio is near
to 1:1; several developmental stages are delineated in gameto-
genesis; spawning takes place in July (10-17°C) with peaks of
larvae in the plankton in July-August; settling is maximum in
less than 5 m.]

Manpryka, O. N. 1979. Features of the linear growth of Pa-
tinopecten yessoensis in populations of the Sea of Japan. BMV,
no. 3, pp. 39-43(ES).

[Five populations from various parts of the area were studied;

differences of growth rate differed by area; maximum length

(220 mm) was found in western areas and the length of life does

not exceed 11 years.]

MARGULIS, B. A., A. D. TARTAKOVSKI] & G. P. PINAEV. 1978.
The protein-contracting albumens of the molluscan adductor
muscles. III. Electrophoretic methods of analysis for the ex-
traction of actinomyosin and paramyosin. SFC, no. 3, pp. 71-
75:

MatTvEEva, T. A. 1979. Adaptations of egg bearing in some
bivalve species. TZI 80:39-43.

[Examples are given of various Arctic bivalves that brood their

eggs and embryos to protect them from unfavorable external

conditions. |

MOoTAVKIN, P. A., A. A. VARAKSIN & L. A. KOSENKO. 1978.
Seasonal characteristics of spermatogenesis in C7venomytilus
grayana. SRF, USSR, no. 3, pp. 58-61.

[In June at the time of spawning, maximum maturity is at-

tained.]

NATOCHIN, YU. V., O. Yu. MIKHAILOVA, E. A. LAVROVA & V.
V. KHLEBOVICH. 1979. Water and electrolytes in the adductor
muscles of Mytilus edulis during acclimatization to lower sa-
linity in vivo and in vitro. ZEBF 15(4):419-425(ES).

[Acclimatization of adductor cells to altered salinities is not mod-

ulated by neurohumoral influences. ]

NATOCHIN, Yu. V., O. Yu. MIKHAILOVA, E. A. LAVROVA & V.
V. KHLEBOVICH. 1979. Water content and electrolytes in ad-
ductor muscles of Mytilus edulis in a wide range of salinities.
BMV, no. 4, pp. 54-60(ES).

[Muscle preparations exposed to different salinities showed cor-

relative concentrations of sodium, potassium, and magnesium. ]

NIKIFOROV, S. M. 1979. On the systematics of oysters from the
southern Primorye [province of far eastern USSR]. BMV, no.
5, pp. 25-33(ES).

[Despite contentions of previous authors (RAZIN, 1934; HIRASE,

1930), who recognized 3 separate species (gigas, laperousi and

posjetica), electrophoretic analyses show that only a single species,

Crassostrea gigas, is present, supporting a view held by SKARLATO

(1960).]

Petrov, S. A. & A. YA. ROZANOV. 1979. The influence of func-
tionally associated vitamins on the loss of 35S lipid acidity in
Black Sea mussels from marine waters. Vzaimodeistvie mezh-
du vodoi i zhiv. veschestvom. Trudi Mezhdunar. Simpoz.
Odessa 1975. (Mutual interaction between water and living
matter. Works of an International Symposium. Odessa). Vol.
2, Moscow, 1979, pp. 190-191.

[The complex of vitamins basically increases the loss of lipids in

ocean water. |

PipaEV, G. P. & S. YU. KHAITLINA. 1978. The protein-contract-
ing albumen of the molluscan adductor muscles. I. Peculiari-
ties of the adductor apparatus of freshwater mollusks and per-
spectives for its study. SRF, no. 3, pp. 62-65.

[Structural and physiological peculiarities of various muscles are

Notes, Information & News

determined by differences in the composition of minor protein-
contracting albumens, which perform regulatory functions. ]

PLISETSKAYA, E. M., L. B. SOLTITSKAYA & L. G. LEIBSON. 1979.
The role of insulin in metabolic regulation in marine bivalves.
ZEBF 15(3):288-294.

[Changes in carbohydrate metabolism develop more rapidly in

mobile mollusks (Pecten) than in sedentary forms (Mytilus).]

Sapkov, A. N. & N. L. SEMENOva. 1979. The biocenosis of
Portlandia arctica-Nuculana pernula (Mollusca, Bivalvia) in
Kandalaksh Bay, the White Sea. ZZ 58(6):797-803(ES).

[The community dominated by these two species (up to 60% of

the total biomass which ranges from 10 to 60 g/m? extends to

120 m in depth.]

SaDyKHova, I. A. 1979. Biological characteristics of Mya are-
naria in the White Sea. ZZ 58(6):804-809(ES).

[In Chupa Inlet of Kandalaksha Bay, most Mya arenaria repro-
duce in mid-July; young measure 0.3 to 0.5 mm in the last days
of July. Salinities of less than 18%o are not favorable for growth
and individuals in the 3-5 year category predominate. Individ-
uals measuring 70-79 mm are 8-10 years of age or more. In-
dividuals 30-45 mm long or 3-4 years old are sexually mature.
Siphons are often damaged by predatory sandpipers.]

SHAKHMAEV, N. K. 1979. The accumulation of manganese in
Anodonta anatina. ZZ 58(6):919(ES).

[In mussels in the Miassa River, Chelyabinsk Prov., significant

amounts of Mn were found in the foot, gonads, and gills where

the concentration is highest at 7.15 mg/g.]

SHELUD’KO, N. S., S. Yu. KHAITLINA & G. P. PINAEV. 1978.
The protein-contracting albumens of the molluscan adductor
apparatus. II. The albumen contents of myofibrils of 2 species
of mollusks and of a rabbit. SRF, no. 3, pp. 66-70.

[Patinopecten yessoensis and Mercenaria stimpsoni were exam-

ined. |

SHELUD’KO, N. S., C. Yu. KHAITLINA & G. P. PINAEV. 1978.
The protein-contracting albumens of molluscan adductor mus-
cles. IV. A study of the extraction of several protein-contract-
ing albumens from the adductors of Patinopecten yessoensis.
SRF, no. 3, pp. 76-80.

SKARLATO, O. A. 1979. Bivalves of economic importance and
their role in the ecosystem. Zool. Inst. Acad. Sci. USSR, 131
pp., ill.

[Species of the genera Mytilus, Crenomytilus, and Modiolus were

considered in regard to their distribution and population dynam-

ics. ]

SKARLATO, O. A. & YA. I. STAROBOGATOV. 1979. The systematic
position and distribution of mussels. PDM, pp. 106-111.

[The following are treated: Subfamily Mytilinae, comprising 4

genera, Crenomytilus lives in the northern part of the Pacific; its

single Recent representative, C. grayanus grayanus, is a Pacific

Asiatic low boreal species found in subtropical waters. Mytilus

embraces 2 subgenera, the nominative and Crassimytilus, n. gen.,

with type-species M. coruscus. This is a Pacific Asiatic subtrop-

ical species. The nominative subgenus includes 2 species: M.

edulis has 4 subspecies, 2 of which are new. The range is am-

phiboreal; and M. galloprovincialis is an Atlantic and Mediter-
ranean European low boreal subtropical species. ]

SKARLATO, O. A. & YA. I. STAROBOGATOV. 1979. Basic features
of the evolution and systematics of the Class Bivalvia. TZI 80:
5-38.

[The following stages can be seen in the evolution of the Bivalvia:

(1) The formation of a monomyarian condition with a straight

dorsal margin; (2) The formation of the Protcbranchia; (3) The

formation of the Autobranchia with their branchial filtering ap-

Page 345

paratus and with a ciliated, water-moving mechanism; (4) The
formation of the Septibranchia with a septal membranous pump;
(5) The adaptive radiation of orders within the limits of the 3
named superorders. The evolution of the stomach and hinge and
also the formation of the basic adaptive type of Bivalvia are
discussed. Data on the systematics of the class, down to families,
are given.]

SKUL’SKI, I. A., I. V. Burovina, N. B. Pivovarova, T. I. IVANOVA
& A. V. LANIN. 1979. Influence of environmental salinity on
the ionic composition of hemolymph and tissue in mussels.
BMV, no. 5, pp. 39-46(ES).

[Concentrations of Na* and Kt were found to be, respectively,

isotonic and hypertonic in samples of Mytilus edulis, Crenomytilus

grayanus, and M. galloprovincialis from the Barents, Baltic, Black,
and Japan seas. |

SOBETSKII, V. A. 1978. The conditions and perspectives of the
study of late Cretaceous bivalves. Dokl. MOIP. Zool. i bota-
nika. Otd. Mosk. o-va. ispyt. prirodi. Moscow. pp. 29-30.

SoBETSKI, V. A. 1979. The all-union symposium on morphol-
ogy, systematics, phylogenesis, and ecogenesis of bivalves. Ti-
raspol, 3-4 Oct., 1978. Paleontol. Zh. 1:152-153.

STADNICHENKO, A. P. 1979. Some morphological regularities of
growth in finger-nail clams (Sphaeriidae). Vestnik Ekologii,
no. 2, pp. 27-32.

[Crimean samples showed correlations in measurements of shell

length, height, and convexity. |

SULTANOV, K. M., S. A. IsaEv & K. F. OGLOBIN. 1978. Bio-
geochemical studies of iron in molluscan shells. Okeanologiya
18(6):1022-1027(ES).

[Iron content was examined in 230 Recent and fossil shells. The

character of change of level of concentration in ontogeny was

traced, as well as its dependence on ecological factors, the growth
rate, and the organic contents of the skeleton. The main ways
iron enters shells are discussed. ]

SVESHNIKOV, V. A. 1979. The morphology of mytilid larvae.
PDM, pp. 103-104.

[The larval shell and soft parts are described; these are in the

water column ordinarily from June-September, and after set-

tling the larval shell-shape is basically preserved into the adult

stage. |

TUuL’cHINSsKAYA, V. P. & V. V. GuBANOov. 1979. A study of the
bacterial contamination by intestinal bacilli and parahemolytic
viruses. PDM, pp. 120-122.

UsHeEva, L. N. & V. M. FaxTor. 1978. A study of the DNA
content in the intestinal epithelium of the yezo scallop. BMV,
no. 4, pp. 81-84(ES).

[The nucleus of intestinal cells of Patinopecten yessoensis has a

diploid quantity of DNA.]

UsHEVA, L. N. 1979. Cellular structure of the epithelium of the
digestive diverticulum in Patinopecten yessoensis. BMV, no. 4,
pp. 61-67(ES).

[The cells are characterized histologically and autoradiographi-

cally.]

WIEGMAN, E. P. 1979. On growth rates in Crenomytilus grayanus
(Cyrtodontida, Mytilidae) in Vostok Cove (Peter the Great
Bay). ZZ 58(4):605-607(ES).

[On the average, mussels grow 12.4 mm the first year and 11

mm the second year; they become sexually mature at 60-70 mm. ]

WiEGMAN, E. P. 1979. Survival of mussels in the aggregate
masses of Crenomytilus grayanus (Cyrtodontida, Mytilidae).
ZZ 58(3):306-313.

[Like many mytilids, Crenomytilus grayanus forms aggregate

Page 346

The Veliger, Vol. 27, No. 3

masses of shells among which young settling mussels find a safer
place for settlement. ]

YAROSLAVSTEVA, L. M. & S. V. FEDOSEEVA. 1978. Adaptations
of some marine mollusks to life in estuaries. BMV, no. 5, pp.
20-25(ES).

[Nuttallia olivacea and Venerupis japonica were studied in relation

to the cellular mechanisms in adapting to lowered salinity; prin-

cipal correlation to survival to decreased salinities was organism-
ic, 7.e., depth of burrowing. |

ZHUCHIKHINA, A. A. & I. A. SKUL’SKII. 1979. Characteristics of
ionic potassium activation of muscular pyruvate kinase in mol-
lusks living in various salinities. BMV, no. 2, pp. 82-86(ES).

[Using Mytilus edulis, M. galloprovincialis, Crenomytilus grayanus,

and Anodonta cygnea, the authors show that the activation of

pyruvate kinase by ionic potassium is higher in tissues of those
inhabiting fresh, or lower salinity, water.]

ZOLOTAREV, V. N. & N. I. SELIN. 1979. The use of shell age-
markings for the study of the growth rates in the mussel,
Crenomytilus grayanus. BMV, no. 5, pp. 77-79(ES).

[Radioactive labelling showed that the invagination of the inner

aragonitic layer into the outer calcitic layer takes place during

the course of one year.]

ZOLOTAREV, V. N. 1978. On changes in the growth rate of
marine mollusks. 2SC, pp. 41-42.

[Contrasts in the growth rates were studied in populations of

Crenomytilus grayanus over the years 1855-1875 and 1920-1940. ]

CEPHALOPODA

Korzun, Yu. V., K. N. Nesis, CH. M. NIGMATULLIN, A. A.
OSTAPENKO & M. A. PINCHUKOV. 1979. New data on the
distribution of the Ommastrephidae in the world ocean.
Okeanologiya 19(4):707-711(ES).

[Illex illecebrosus illecebrosus was taken in the Mid-Atlantic Ridge

(48°30'-56°N), J. 2. comndetti from off Namibia (17°30’S), and the

supposed bottom dwelling J. 7. argentinus was captured on the

surface above the continental slope and deep ocean. Todaropsis
eblanae was found in the SW part of the Indian Ocean (Saya-
de-Malha and Nazareth Banks of the Sea of Timor). Todarodes
angolensis was taken near New Zealand, the Auckland and

Campbell Islands, and SW and S of Tasmania. Other new data

include: Notodarus sloani (possibly a subspecies) off southern So-

malia and on the Saya-de-Mahla Bank; Eucleoteuthis luminosa
in the SE part of the Indian Ocean and off the Norfolk Islands.

Todarodes sagittatus is widely distributed over the Mid-Atlantic

Ridge and on seamounts of the non-tropical North Atlantic,

especially on the Kelvin and Corner Seamounts. For the south-

ern form of O. bartrami, the part of its range in the Indian Ocean
is isolated from the Pacific Ocean portion. Spawning swarms
were observed near Idzu and Norfolk Islands. ]

Nesis, K. N. 1978. Nautilus in aquaria. Priroda, no. 7, pp. 43-
50.

[Nautilus grows and matures at depths of 100 or 200 to 500 m

at 14~16°C, but reproduces in shallow reefs at 25-30°C. Mating

takes place from June to August or September and spawning a
few weeks afterwards. Eggs are deposited singly at night; they
are oval, 20-40 mm long by 15-35 mm in diameter, weigh about
3.5 g, and are encapsulated in a cartilaginous covering; 10-11
eggs are laid. Incubation apparently takes about half a year.
Hatching takes place when the juveniles are about 2 cm in di-
ameter. Nautilus is nocturnal and hides during the day in dark
places or clings strongly to boulders with its tentacles. They
move slowly. Buoyancy is regulated by changing the osmotic
pressure in the cameral fluids. They feed on weakly moving or
motionless prey. Vision is poor but they react strongly to sound
and have a well developed chemotactile sense. ]

Nests, K. N. 1979. The larvae of Cephalopoda. BMV, no. 4,
pp. 26-37(ES).

[All cephalopods do not have direct development; they may have

a pelagic larval stage or a-direct benthonic one. Postnatal onto-

genesis may include various phases, 2.e., from hatching to ab-

sorption of the internal yolk sac or from larval fry to subadult,

sometimes accompanied with allometric growth of organs. ]

NeEsis, K. N. 1979. Larvae of the squid family Ommastrephidae.
ZZ 58(1):17-30(ES).

(The larvae of 12 species and 8 genera are described and figured;
generic determination is possible in the rhynchoteuthis stage but
specific characteristics do not appear until later. Zuev’s phylo-
genetic scheme is basically correct for the higher classification;
however, Ornithoteuthis should be placed into separate subfamily
while Dosidiscus is derived from the earliest common ommastre-
phid stock. ]

Nesis, K. N. & CH. M. NIGMATULLIN. 1978. A discovery of an
egg mass of the bottom octopus Eledone caparti (Octopodidae)
in stomachs of deep-water blue sharks. ZZ 57(9):1324-
1329(ES).

[From 250-380 km, off the coast of Dakar and Cabo Verde,

Senegal, 3 blue sharks were taken by longline and their stomachs

contained undigested egg masses of 2800-5100 eggs of, presum-

ably, Eledone caparti; the embryos were at stage XIII; eggs at
early developmental stages measure 8.9 x 3.8 mm, slightly larg-
er than those of E. cirrosa.]

NEsis, K. N. & Cu. M. NIGMATULLIN. 1979. Distribution and
biology of Ornithoteuthis Okada, 1927 and Hyaloteuthis Gray,
1849 (Oegopsida). Byul. Mosk. o-va. ispit. prirodi, Otd. Biol.
84(1):50-63(ES). (Bull. of the Moscow Naturalists Society,
Series Biology).

[From plankton hauls and fish stomachs, the authors showed the

geographic and vertical distribution, size at sexual maturity, and

other ecological data for Ornithoteuthis antillarum, O. volatilis, and

Hyaloteuthis pelagica; species of Ornithoteuthis were tropical ne-

rito-oceanic, actively attacked by predators, and smaller at ma-

turity.]

SHEvTsovaA, S. V., A. P. BESTKIN, K. N. NeEsis & E. V.
ROZENGART. 1979. Divergences in the properties of cholin-
esterases in the visual ganglia of Ommastrephis bartrami (Les.):
squids as an index of the isolation of populations in various
parts of a discontinuous range. Okeanologiya 19(3):481-
486(ES).

Notes, Information & News

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CONTENTS — Continued

A comparison of two Florida populations of the coquina clam, Donax variabilis
Say, 1822 (Bivalvia: Donacidae). II. Growth rates.
PAUL(S: MIKKEESEN (2022.2 in, oc ae eis ote) ASPs ee eee 308

Comparative shell microstructure of North American Corbicula (Bivalvia:
Sphaeriacea).
ROBERT S. PREZANT AND ANTONIETO, TAN-TIW 20). 92 pee SWZ

A new species of Sphenia (Bivalvia: Myidae) from the Gulf of Maine.
ROBERT W: HANKS AND DAVID'B.| PACKER’). 0°55 035.) 20) ce) eee 320

An anesthetic for internal operations on the land snail Helix aspersa Miiller.
DANIEL, GHUNG) sc Osseo! vg bahar hon ce ner an ae Oe dae oe ee oe eer ga)

Two new northeastern Pacific gastropods of the families Lepetidae and Seguen-
ziidae.
JAMES HT MCLEAN |: 000 co 38 cee paicte te 8 6 ee eee ee ee 336

NOTES, INFORMATION & NEWS
Soviet contributions to malacology in 1979.
Morris K. JACOBSON AND KENNETH J. BOSS: 22 (j).¢:0 3 ee ae oy)

17]

ISSN 0042-3211

ITHE

VELIGER

HA Quarterly published by

CALIFORNIA MALACOZOOLOGICAL SOCIETY, INC.
Berkeley, California

BR. Stohler, Founding Editor

Volume 27 April 1, 1985 Number 4

CONTENTS

Adaptive value of shell variation in Thais lamellosa: effect of thick shells on
vulnerability to and preference by crabs.
ENS TSSCTS UNI) Dyed e228 DI 0) So oars Ha 2 Pars Pa ene ET SS Ar 349

Gastropod feeding tracks as a source of data in analysis of the functional mor-
phology of radulae.
CAROLE S: HICKMAN AND COME. MORRIS 22S a eo erg ei oe 35//

Predation by Nucella cingulata (Linnaeus, 1771) on mussels, particularly Aula-
comya ater (Molina, 1782).
Aghl ACeNVICKENS) AND) CHARLES 1.) GRIPFIPHS 3) 2)00 0 0 ual. taal « 366

The activity pattern of Onchidella binneyi Stearns (Mollusca: Opisthobranchia).
PEEP ee EPEVAND)OUEANNE) Mis PEPE 7240255 6) sae es te ne 2)

A mass mortality of northern bay scallops, Argopecten irradians irradians, follow-
ing a severe spring rainstorm.
STEPHEN T. TETTELBACH, PETER J. AUSTER, EDWIN W. RHODES, AND JAMES
OANA NANG Ss i a veh Str one ae aaa oh ana AU DEES As Ny He 381

Shell growth, trauma, and repair as an indicator of life history for Nautilus.
RIOEUNG WIG NRIN OLD eae yA rises Me ean Solace CoN N AT. IMME NN ISHAM cM 386

Records and morphology of Lomanotus stauberi Clark & Goetzfried, 1976, from
the Panamic Pacific.
(LERRENCE, Me.GOSLINER AND) HIANS ‘(BERTSGH) 2.0 0022 ee 397

Rediscovery and redescription of Rostanga lutescens (Bergh, 1905), comb. nov.
(Gastropoda: Nudibranchia).
S COM) OHNSONVANDIELANS (BERDSCH a) (5). c1 eine ie eek ain me ae 406

CONTENTS — Continued

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THE VELIGER

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The Veliger 27(4):349-356 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

Adaptive Value of Shell Variation in Thais lamellosa:
Effect of Thick Shells on Vulnerability to

and Preference by Crabs

by

A. RICHARD PALMER

Department of Zoology, University of Alberta, Edmonton, Alberta T6G 2E9 and
Bamfield Marine Station, Bamfield, British Columbia VOR 1B0, Canada

Abstract.

Laboratory experiments with the predatory shallow-water crab Cancer productus revealed

that thin-shelled individuals of the morphologically variable prosobranch gastropod Thais lamellosa
(Gmelin, 1791) (=Nucella lamellosa; Muricacea; Thaididae) were significantly more likely to be eaten
than thicker shelled individuals. Three of five crabs of different sizes (8.0-16.5 cm carapace width)
were able to eat the largest thin-shelled snail offered (>45 mm shell length) over a period of 55 days.
However, only the largest crab ate more than 10% of the thick-shelled snails offered over this same
time period, and it was also able to eat the largest thick-shelled snail available (44.6 mm); hence, thick
shells did not guarantee immunity from predation. Significantly, the few snails eaten from the “‘thick-
shelled” population by the remaining four smaller crabs averaged nearly two standard deviations
(mean = 1.99) lighter than the mean for animals of comparable length from that population, revealing
that individuals further from the mean were selected against. The time sequence of consumption
suggested that motivational state strongly influenced whether a crab attacked thick-shelled snails suc-
cessfully: for all but one crab, thick-shelled snails were not consumed until more than 50% of the thin-
shelled individuals had been eaten.

The adaptive value of thick shells appears to result from two factors: (1) a decrease in the range of
sizes of crabs to which a snail of a given body size is ultimately vulnerable, and (2) a decrease in the
desirability of snails to the larger crabs to which they are still vulnerable. Variation in shell thickness
probably persists in Thais lamellosa, however, because thinner shells are favored in the absence of crabs:
they are less expensive to produce and to transport, and they permit more rapid growth when food is

abundant.

INTRODUCTION

THE SHELLS OF Thais lamellosa (=Nucella lamellosa) are
among the most variable of those of prosobranch gastro-
pods from the Pacific coast of North America; they vary
extensively in color, banding, sculpture, thickness, and
shape (ABBOTT, 1974; KINCAID, 1957; KITCHING, 1976;
SPIGHT, 1973, 1976). The variation in shell sculpture and
thickness is perhaps the most dramatic; it is often corre-
lated with habitat, and the mean phenotype of populations
can change dramatically over distances as short as a few
hundred meters (Palmer, unpublished). The adaptive val-
ue of shell variation in this species, however, has not been
addressed experimentally. Because increased shell thick-

ness in 7. lamellosa is often associated with habitats in
which crabs, in particular Cancer productus, are abundant,
I examined the effectiveness of thick shells as deterrents
to this shell-breaking predator (ZIPSER & VERMEIJ, 1978).
In addition, because larger crabs generally are capable of
eating larger gastropods (VERMEIJ, 1978), I examined the
relationship between crab size and relative vulnerability
of thin- versus thick-shelled snails.

METHODS

Thais lamellosa of two substantially different shell mor-
phologies (comparable to illustrations 1905 and 1908 of
ABBOTT, 1974) were collected in early February from two

Page 350

The Veliger, Vol. 27, No. 4

Table 1

Offered sizes, eaten sizes, and “critical sizes” (defined in
text) at the termination of the experiment, of thin- and
thick-shelled Thazs lamellosa for each of the five Cancer
productus used in the experiments. Crab sizes are carapace
widths. Twenty-one snails were offered initially in each
group, eaten snails were not replaced. Question marks
following critical sizes indicate unrepresentative values
because many smaller snails were available but not eaten.

Thais lamellosa shell length (mm)

Final
Crab ONES we “critical
size Shell Small- Larg- Small- Larg- size”
(cm) form est est est est n (mm)

8.0 Thin 23:5" “46:39 23°5 39:3. 18 42.9
Thick 20.1 46.2 22.8 22.8 1 24.0?

9.1 Thin 210) 45:55 21005 45.51" 2 ile 4555
Thick 21.4 42.4 29.4 29.4 ‘1 2951

9.2 Thin 21.3 48.0 21.3 48.0 21 >48.0
Thick 20.2 46.0 20.0 46.0 2 >46.0?

135) Thins 21-8) 528) 2218s 5274520 52.6
Thick 19.5 50.7 _ — O <19.5

16.5 Thin 22.7 54.8 22.7 54.8 21 >54.8
Thick 21.5 446 215 446 20 >44.6

different habitats on San Juan Island, Washington (USA).
Thin-shelled, strongly sculptured individuals were col-
lected at low tide from an isolated, offshore rock surround-
ed by deep water and swept by strong tidal currents (Turn
Rock, 48°32'N, 122°58'W), and thick-shelled, smooth in-
dividuals were collected from rocky substrata in quiet water
surrounded by a muddy bottom near the east shore inside
the mouth of False Bay (48°29'N, 123°04'W). The snails
were numbered individually (PALMER, 1980), and mea-
sured for shell length (apex to tip of siphonal canal) to
0.1 mm with vernier calipers. To estimate shell weight,
live animals were immersed in seawater, and immersed
weights were converted to shell dry weights using the
regression: shell dry weight (g) = 1.572 immersed weight
(g) + 0.0162 (7? = 0.9998; from PALMER, 1982). To mea-
sure the body size of the animals (excluding the shell),
tissue wet weight was also estimated for a subsample from
each population by subtracting estimated shell weight
from the whole weight of the animals in air (PALMER,
1982).

Five specimens of Cancer productus of different sizes
(8.0-16.5 cm carapace width) were collected, from False
Bay, during nighttime low tides over several weeks prior
to the experiments. Each specimen was placed individ-
ually into shallow concrete seawater trays (30 x 50 x 15
cm) supplied with running seawater at the Friday Harbor
Laboratories, Friday Harbor, Washington (USA). These
trays were adjacent to a south-facing window, and no

attempt was made to regulate lighting conditions. I did
not attempt to standardize hunger levels of the crabs prior
to the experiments, but over the duration of the experi-
ments the only food available to the crabs was the intro-
duced snails. Water temperatures ranged from 6.5 to 7.7°C.

The experiments were initiated by introducing simul-
taneously into each aquarium 21 snails of a comparable
size range for each shell type (Table 1). The behavior of
the crabs was observed closely over the first five and one-
half hours to evaluate their initial responses to the snails;
these observations were not continued on subsequent days
because feeding activity was too unpredictable. Snails
crawling up the sides of the aquaria were knocked back
onto the bottom daily for the first two weeks, and every
two to four days for the remainder of the experiment to
ensure their availability to the crabs. Both dislodged and
attached snails were equally likely to be attacked by a
crab. The snails remaining in each aquarium were noted
nine times over the next 55 days (Feb. 12-April 3). Fol-
lowing each enumeration, the bottoms of the aquaria were
siphon-vacuumed to collect all shell fragments, and the
fragments were examined for the presence of numbered
tags to verify that missing snails had in fact been eaten.
Of the 210 snails used in these experiments, only one
disappeared without being eaten, and one died from other
causes; these were not included in the analyses.

Regression lines were compared using analysis of co-
variance (ANCOVA), and differences among expected
means were compared using the appropriate standard
errors (SOKAL & ROHLF, 1981).

RESULTS

Differences in shell weight between the two populations
of Thais lamellosa were highly significant: for animals of
the same shell length, those from False Bay ranged from
50 to 100% heavier with increasing size (shell weight for
the False Bay population was significantly higher for all
positive shell lengths [P < 0.001, comparison of predicted
mean weights from shell length for both populations)),
and larger animals had proportionally heavier shells (the
slope for the thick-shelled population was significantly
higher than that for the thin-shelled one [P < 0.001, AN-
COVA; Figure 1a]). For both populations, the slopes were
significantly less than 3.0 (P < 0.001; Figure 1a), reveal-
ing a negative allometry in each. Rather curiously, in spite
of the differences in shell weight, the tissue weights of
animals of the same shell length did not differ between
the two populations (P > 0.45; Figure 1b); hence, the body
size of animals from both populations could be predicted
from the same regression on shell length. Geometrically,
this means that the shells of individuals from the thick-
shelled population were wider for a given length.

Initial feeding activity varied rather markedly among
crabs. During five and one-half hours of continuous ob-
servation on the first day of the experiment, two of the
crabs (8.0 and 16.5 cm carapace width) did not even at-

A. R. Palmer, 1985

Shell Weight (g)

Body Weight (g)

20

Page 351

25 30 35

Shell Length (mm)

Figure 1

The relationships with shell length of shell weight (a) and body wet weight (b) for a thick- (circles) and a thin-
shelled (triangles) population of Thais lamellosa. Solid circles in (a) indicate individuals eventually consumed by
the smaller four crabs (see text). In (a), the regressions (+SE) of log shell weight (Y) on log shell length (X) for
the two populations were: thick-shelled population, Y = 2.787(+0.060)X — 3.5030(+0.006), N = 106, 7? = 0.953;
thin-shelled population, Y = 2.450(+0.050)X — 3.2588(+0.005), N = 106, 7? = 0.958. These slopes were signif-
icantly different (P < 0.001, ANCOVA). In (b) log(body wet weight) = 3.1904(+0.105)log(shell length) —
4.9279(+0.009) (both populations combined; neither the slopes nor the adjusted means from ANCOVA were
significantly different between populations [P = 0.45 and P = 0.79 respectively]).

tempt to eat any snails and one (13.5 cm) only investigated
two thick-shelled snails but did not attempt to break their
shells. A fourth crab (9.2 cm) attacked two thin- and three
thick-shelled snails; it consumed one, and badly damaged
the shell of the other thin-shelled individual, but it was
unable to inflict any damage on the three thick-shelled

animals. In contrast, the fifth crab (9.1 cm) attacked and
consumed five thin-shelled snails, and attacked two thick-
shelled individuals unsuccessfully.

Differences in feeding behavior among crabs persisted
for the first two weeks of the experiment (Figure 2). Within
eight days of the start of the experiments, three of the five

Page 352 The Veliger, Vol. 27, No. 4

100 pes) ) ene
°
<n bs oe ne
S 80 oe
uJ yh
r= 7
2 60 /
7
a 7
7
S 40ty /
o re
2 _--o
— Sis
6g 20 e/ o—-—-0-—
—_—-O
a a ee ew 00 = HLL K-00
O00 — ee ee () X =A—
30 40 50
Time (d)
Figure 2

Cumulative percent of thick- and thin-shelled Thais lamellosa consumed as a function of time by each of five crabs.
Solid symbols with solid lines: snails from the thin-shelled population. Open symbols with dashed lines: snails from
the thick-shelled population. Different symbols correspond to crabs of different carapace widths: circles, 8.0 cm;
diamonds, 9.1 cm; squares, 9.2 cm; triangles, 13.5 cm; hexagons, 16.5 cm.

specimens of Cancer productus had eaten nearly 50% of snails of the two different shell types were consumed at
the thin-shelled Thais lamellosa. The remaining two did significantly different rates (Figure 2; thin = 0.36 snails/
not consume that many of the thin-shelled form until after day, thick = 0.09 snails/day; P = 0.025, Mann-Whitney
two weeks had elapsed. U-test). Only the largest crab (16.5 cm carapace width)

In spite of the variation in feeding behavior among crabs, ate many of the thick-shelled form; after 55 days it had

Thais Shell Length (mm)

8 10 l2 14 16
Cancer Carapace Width (cm)

Figure 3

Shell lengths of the largest three thin-shelled Thazs lamellosa eaten at LD 50 as a function of Cancer productus size
(carapace width). Open symbols, individual snails; solid symbols, mean. N = 15, 7? = 0.609, P < 0.01.

A. R. Palmer, 1985

‘Critical Size’ (mm)

Estimated

Page 353

30 40 50
Time (d)
Figure 4

Change in the estimated “critical size’ (mean shell length of the largest snail eaten and the next largest available;
VERMEIJ, 1976) for each of the five crabs over the duration of the experiment. Dashed lines indicate that the largest
available snail had been consumed during that interval; thus the estimated critical size would probably have

continued to increase. Symbols for the crabs as in Figure 2.

consumed all but one of the initial 21 thick-shelled snails,
in addition to all of the thin-shelled ones. The remaining
four crabs ate at most only two of the 21 available thick-
shelled snails even though three of them had eaten all, or
all but one, of the thin-shelled snails. In addition, only
one of these four crabs ate a thick-shelled snail before 50%
of the thin-shelled snails had been eaten in its aquarium
(Figure 2), and it was the only thick-shelled snail eaten
by this crab. Thus, many thin-shelled snails were eaten
before the crabs began attacking thick-shelled ones suc-
cessfully.

Finally, the sizes of the largest thin-shelled snails eaten
increased with crab size after 50% of those available had
been consumed (Figure 3), even though, by the end of the
experiment, three of the five crabs had eaten all of the
thin-shelled snails available. Thus, smaller thin-shelled
snails tended to be eaten before larger ones, particularly
for the smaller crabs (see also Figure 4 below). For the
two crabs that did not eat all of the thin-shelled snails,
the final “critical size” (mean of shell length of the largest
snail eaten and the next largest available; VERMEIJ, 1976)
increased with crab size (Table 1). Final critical size was
not related to crab size for the thick-shelled snails (Table
1), because the few snails eaten by the four smaller crabs
were among the lightest of the thick-shelled animals of-
fered, averaging 1.99 SD less than their expected values
from regression (Figure 1a); thus, these values overesti-
mate the actual critical sizes for the thick-shelled popu-
lation.

DISCUSSION

Thaidid gastropods are notorious for their variation in
shell appearance, variation that has been a frequent source
of taxonomic confusion (ABBOTT, 1974; GRANT & GALE,
1931; KINCAID, 1957, 1964; VoKEs, 1971; WELLINGTON
& Kuris, 1983). The conspicuousness of this variation
has resulted in many descriptive studies of geographic pat-
terns within members of this family, including patterns in
shell color (BERRY & CROTHERS, 1968, 1974; Moore,
1936; SPIGHT, 1976) and in shell morphology (CROTHERS,
1982, and references therein; CURREY & HUGHES, 1982;
KINCAID, 1957, 1964; KITCHING, 1976, 1977; PHILLIPS et
al., 1973; SEED, 1978; VERMEIJ & CURREY, 1980). A few
studies have examined experimentally the potential adap-
tive value of morphological variation in these species
(EBLING et al., 1964; HUGHES & ELNER, 1979; KITCHING
& Lockwoop, 1974; KITCHING et al., 1966; WELLINGTON
& Kuris, 1983), and they all have demonstrated, among
other things, that thicker shelled individuals are more re-
sistant to attack by shell-breaking crabs than thinner
shelled ones. The results presented here support the con-
clusions of these experimental studies; however, they also
demonstrate that thicker shells cannot guarantee immu-
nity from predation by large crabs, and they reveal a prob-
able additional advantage to thicker shells that relates to
the motivational state of crabs.

The laboratory feeding experiments with Cancer pro-
ductus yielded three results of significance. First, thicker

Page 354

(=heavier) shelled individuals of Thais lamellosa were con-
sumed at a much lower rate than thinner (=lighter) shelled
ones by all sizes of crabs. Second, the largest C. productus
was nonetheless capable of eventually consuming all sizes
of the thicker shelled snails offered (up to 44.6 mm). Third,
the successful attack of thicker shelled or larger snails was
influenced by the availability of thinner shelled or smaller
animals.

I use shell weight as interchangeable with shell thick-
ness because of the convenience with which it can be mea-
sured and because I feel it is a more useful single measure
of average thickness. Local increases in thickness associ-
ated with axial sculpture or apertural teeth make thick-
ness measurements of a specific part of the shell arbitrary
and sometimes difficult to interpret. Apertural teeth and
axial sculpture may thicken the lip, reducing vulnerability
to crabs that peel shells starting at the aperture, but such
shells would still be vulnerable to crabs that crush (VER-
MEIJ, 1978). Cancer productus uses both techniques (ZIP-
SER & VERMEIJ, 1978); thus, shell weight provides a mea-
sure of average shell thickness that is more likely to reflect
relative vulnerability of snails to this crab.

The adaptive value of thick shells appears to be a
consequence of two factors. First, thicker shells decrease
the size range of crabs to which snails of a given body size
are ultimately vulnerable (see also REIMCHEN, 1982). The
four smaller crabs in the experiments ate at most two of
the available thicker shelled morph of Thais lamellosa, and
all of these eaten snails had the thinnest shells of those
available of comparable length (Figure 1a). Thus, sufh-
ciently thick shells can render their bearers invulnerable
to attack from all but very large crabs. This in turn re-
duces the total number of crabs to which the snails are
potentially vulnerable and hence reduces their overall
probability of mortality.

A second advantage to thicker shells results from the
selective feeding behavior of crabs. When a diversity of
prey is available, predators usually feed preferentially on
the energetically more valuable prey (HUGHES, 1980;
HUGHES & ELNER, 1979; PALMER, 1984). By increasing
both the energy expended and the time required to break
open a shell successfully, thicker shells will decrease the
potential food value of snails to shell-breaking predators.
This decrease in potential food value probably accounts
for an aspect of the feeding behavior exhibited by all but
one of the crabs that consumed one or more thick-shelled
Thais lamellosa: the thick-shelled snails were not attacked
successfully until more than 50% of the thin-shelled ones
had been eaten (Figure 2). For the largest crab, which ate
nearly all of the thick-shelled snails offered, 80% of the
thick-shelled individuals were eaten only after all of the
thin-shelled snails had been consumed (Figure 2). Had
thinner shelled snails been replaced as they were eaten,
the remaining 80% of the thick-shelled animals probably
would not have been eaten. These results suggest strongly
that thicker shelled snails were manipulated but rejected
as undesirable by crabs earlier in the experiments.

The Veliger, Vol. 27, No. 4

Similarly, at 50% mortality of the thin-shelled snails,
the mean size of the largest snails eaten increased with
crab size (7? = 0.61; Figure 3), presumably reflecting an
increase in the “preferred size” for the larger crabs when
thin-shelled snails were initially abundant (ELNER &
HUGHES, 1978). However, by the end of the experiments,
the largest four crabs had eaten all, or all but one, of the
thin-shelled Thais lamellosa. Hence, although larger snails
were ultimately vulnerable, they were not consumed until
most of the smaller ones had been eaten, again suggesting
they were manipulated and rejected earlier in the exper-
iment. Access to alternative prey of higher food value (en-
ergy/unit time, or potential for promoting growth; PALM-
ER, 1983a) thus appears to influence substantially the
probability of being eaten of more heavily defended or
larger prey that are nonetheless still potentially vulner-
able to crabs. A similar conclusion has been reached by
BOULDING (1984) from experiments with Cancer pro-
ductus feeding on infaunal bivalves.

In these experiments, the increase over time in the max-
imum size of snail eaten by individual crabs points to a
methodological difficulty associated with measuring the
“critical size” of different shell forms (maximum size of
vulnerability to a given size and species of shell-breaking
predator [VERMEIJ, 1976]—a larger critical size means
snails are vulnerable to a larger size, 1.e., are more vul-
nerable). Clearly, the estimated critical size (mean size of
the largest individual eaten and the next largest one avail-
able) depends upon the duration of the experiment (Fig-
ure 4). It will also depend upon the availability of alter-
native prey. When a number of prey are offered
simultaneously to a predator, curves such as those of Fig-
ure 4 will increase confidence in the accuracy of the ex-
perimentally measured critical sizes (see also BOULDING,
1984), particularly for crabs, whose feeding activity in the
lab is often erratic and unpredictable.

Finally, if thicker shells significantly reduce vulnera-
bility to shell-breaking predators, why are not all popu-
lations of Thais lamellosa in particular, or all species of
marine gastropods in general, thick-shelled? Presumably,
the costs of a thicker shell outweigh the advantages in
some cases. Shell material, or at least the organic matrix
of shells, appears to be energetically expensive to produce
(PALMER, 1983b, and references therein). Heavier shells
are also more expensive to transport in surface-dwelling
species; a two-fold increase in shell weight results in near-
ly a three-fold increase in the cost of locomotion in 7.
lamellosa (Palmer and LaBarbera, in preparation). In ad-
dition, the maximum rate of body growth in 7. lamellosa
is limited by the rate at which shell material can be pro-
duced rather than by the rate of ingestion or rate of tissue
production (PALMER, 1981); thus, a thicker shelled indi-
vidual would not be able to grow as rapidly as a thinner
shelled one even when food is not limiting. All of these
costs will counteract the selection for thicker shells as mor-
tality due to shell-breaking predators decreases. The shell-
thickness polymorphism in Thazs lamellosa probably per-

A. R. Palmer, 1985

Page 355

sists because genetic fixation is prevented by some com-
bination of (1) gene flow among adjacent populations sub-
ject to different intensities of predation, and (2) temporal
fluctuations in crab abundance, which favor different phe-
notypes at different times at a given site.

Uncertainty exists over the degree of genetic control of
intraspecific variation in shell morphology of thaidid gas-
tropods. Because the variation among populations is usu-
ally greater than that within, it is often assumed to be
genetic (CROTHERS, 1974, 1982; KINCAID, 1957; KiITCH-
ING & Lockwoop, 1974). However, the same pattern
would result if this morphological variation were purely
phenotypic. Growth in the laboratory of young individuals
collected from populations of different adult morphology
suggests that considerable phenotypic plasticity exists in
the shell sculpture of Nucella lapillus (LARGEN, 1971) and
shell shape of Thais lamellosa (SPIGHT, 1973). Breeding
studies with 7. emarginata have revealed that variation in
spiral shell sculpture has both a genetic and an environ-
mental basis (PALMER, 1985). Of the shell features that
vary in both 7. emarginata and T. lamellosa, shell thickness
appears to be the most phenotypically labile (Palmer, un-
published), suggesting provocatively that these gastropods
may be capable of producing predator-resistant shells in
direct response to potential predation by crabs, as de-
scribed for rotifers (GILBERT, 1966), bryozoans (YOSHIO-
KA, 1982; HARVELL, 1984), and cladocerans (GRANT &
BAYLy, 1981) in response to their predators. Preliminary
results (Appleton & Palmer, unpublished) have revealed
that both thin- and thick-shelled 7. /amellosa can be in-
duced to produce thicker apertural lips in the presence of
Cancer productus being fed conspecific snails.

ACKNOWLEDGMENTS

Salary while this research was being conducted was pro-
vided by NSF grant OCE 74-21498 to R. R. Strathmann.
I thank the director and staff of the Friday Harbor Lab-
oratories for providing research space and assistance, and
K. Irons and R. B. Lowell for critically reading the manu-
script. Data analysis, writing, and publication expenses
were defrayed by NSERC operating grant A7245 to the
author.

LITERATURE CITED

ABBOTT, R. T. 1974. American seashells. Van Nostrand Rein-
hold Co.: New York. 663 pp.

Berry, R. J. & J. H. CROTHERS. 1968. Stabilizing selection
in the dog-whelk (Nucella lapillus). J. Zool. (Lond.) 155:5-
17.

Berry, R. J. & J. H. CRoruers. 1974. Visible variation in
the dog-whelk, Nucella lapillus. J. Zool. (Lond.) 174:123-
148.

BOuLDING, E. G. 1984. Crab-resistant features of infaunal
bivalve shells: decreasing vulnerability by increasing han-
dling time. J. Exp. Mar. Biol. Ecol. 76:201-223.

CROTHERS, J. H. 1974. On variation in the shell of the dog-
whelk Nucella lapillus (L.) I. Pembrokeshire. Field Studies
4:39-60.

CROTHERS, J. H. 1982. Shell shape variation in dog-whelk
(Nucella lapillus (L.)) from the West Coast of Scotland. Biol.
J. Linn. Soc. 17:319-342.

Currey, J. D. & R. N. HuGues. 1982. Strength of the dog-
whelk Nucella lapillus and the winkle Littorina littorea from
different habitats. J. Anim. Ecol. 51:47-56.

EBLING, F. J., J. A. KitcHinc, L. Muniz & C. M. Tayior.
1964. The ecology of Lough Ine. XIII. Experimental ob-
servations of the destruction of Mytilus edulis and Nucella
lapillus by crabs. J. Anim. Ecol. 33:73-83.

ELNER, R. W. & R. N. HuGHEs. 1978. Energy maximization
in the diet of the shore crab, Carcinus maenas. J. Anim. Ecol.
47:103-116.

GILBERT, J. J. 1966. Rotifer ecology and embryological in-
duction. Science 151:1234-1237.

GRANT, J. W.G. & I. A. E. BAyLy. 1981. Predator induction
of crests in morphs of the Daphnia carinata King complex.
Limnol. Oceanogr. 26:201-218.

GRanT, U.S. & H. R. GALE. 1931. Catalogue of the marine
Pliocene and Pleistocene mollusca of California and adja-
cent regions. Mem. San Diego Soc. Natur. Hist. 1:1-1036.

HARVELL, C. D. 1984. Predator-induced defense in a marine
bryozoan. Science 224:1357-1359.

HuGueEs, R. N. 1980. Optimal foraging in the marine context.
Oceanogr. Mar. Biol. Ann. Rev. 18:423-481.

HuGuHEs, R. N. & R. W. ELNER. 1979. Tactics of a predator,
Carcinus maenas, and morphological responses of the prey,
Nucella lapillus. J. Anim. Ecol. 48:65-78.

Kincaib, T. 1957. Local races and clines in the marine gas-
tropod Thais lamellosa, a population study. Calliostoma Co.:
Seattle.

Kincalp, T. 1964. Notes on Thais (Nucella) lima (Gmelin), a
marine gastropod inhabiting areas in the North Pacific
Ocean. Calliostoma Co.: Seattle.

KITCHING, J. A. 1976. Distribution and changes in shell form
of Thais spp. (Gastropoda) near Bamfield, B.C. J. Exp.
Mar. Biol. Ecol. 23:109-126.

.KITCHING, J. A. 1977. Shell form and niche occupation in

Nucella lapillus (L.) (Gastropoda). J. Exp. Mar. Biol. Ecol.
26:275-289.

KITCHING, J. A. & J. Lockwoop. 1974. Observations on shell
form and its ecological significance in thaisid gastropods of
the genus Lepsiella in New Zealand. Mar. Biol. 28:131-
144.

KITCHING, J. A., L. MuNTZ & F. J. EBLING. 1966. The ecol-
ogy of Lough Ine XV. The ecological significance of shell
and body forms in Nucella. J. Anim. Ecol. 35:113-126.

LarGEN, M. J. 1971. Genetic and environmental influences
upon the expression of shell sculpture in the dog whelk
(Nucella lapillus). Proc. Malacol. Soc. Lond. 39:383-388.

Moore, H. B. 1936. The biology of Purpura lapillus, I—shell
variation in relation to environment. J. Mar. Biol. Assoc.
U.K. 21:61-89.

PALMER, A. R. 1980. A comparative and experimental study
of feeding and growth in thaidid gastropods. Doctoral The-
sis, Univ. of Washington, Seattle. 320 pp.

PaLMER, A. R. 1981. Do carbonate skeletons limit the rate of
body growth? Nature 292:150-152.

PALMER, A. R. 1982. Growth in marine gastropods: a non-
destructive technique for independently measuring shell and
body weight. Malacologia 23:63-73.

PALMER, A. R. 1983a. Growth rate as a measure of food value
in thaidid gastropods: assumptions and implications for prey

Page 356

The Veliger, Vol. 27, No. 4

morphology and distribution. J. Exp. Mar. Biol. Ecol. 73:
95-124.

PALMER, A. R. 1983b. Relative cost of producing skeletal or-
ganic matrix versus calcification: evidence from marine gas-
tropods. Mar. Biol. 75:287-292.

PALMER, A. R. 1984. Prey selection by thaidid gastropods:
some observational and experimental field tests of foraging
models. Oecologia 62:162-172.

PALMER, A. R. 1985. Quantum changes in gastropod shell
morphology need not reflect speciation. Evolution (in press)

PHILLiPs, B. F., N. A. CAMPBELL & B. R. WILSON. 1973. A
multivariate study of geographic variation in the whelk Di-
cathais. J. Exp. Mar. Biol. Ecol. 11:27-69.

REIMCHEN, T. E. 1982. Shell size divergence in Littorina ma-
riae and L. obtusata and predation by crabs. Can. J. Zool.
60:687-695.

SEED, R. 1978. Observations on the significance of shell shape
and body form in the dogwhelk (Nucella lapillus (L.)) from
North Wales. Nature in Wales 16:111-122.

SOKAL, R.R. & F. J. ROHLF. 1981. Biometry. W. H. Freeman
and Co.: San Francisco.

SPIGHT, T. M. 1973. Ontogeny, environment, and shape of a
marine snail, Thais lamellosa (Gmelin). J. Exp. Mar. Biol.
Ecol. 13:215-228.

SPIGHT, T. M. 1976. Color patterns of an intertidal snail,
Thais lamellosa. Res. Pop. Ecol. 17:176-190.

VERMEIJ, G. J. 1976. Interoceanic differences in vulnerability
of shelled prey to crab predation. Nature 260:135-136.
VERMEIJ, G. J. 1978. Biogeography and adaptation. Patterns

of marine life. Harvard Univ. Press: Cambridge. 332 pp.

VERMEIJ, G. J. & J. D. CURREY. 1980. Geographical variation
in the strength of thaidid snail shells. Biol. Bull. 158:383-
389.

VoKES, E.H. 1971. The geologic history of the Muricinae and
the Ocenebrinae. Proc. West. Soc. Malacologists (Echo) 4:
37-54.

WELLINGTON, G. M. & A. M. Kuris. 1983. Growth and shell
variation in the tropical eastern Pacific intertidal gastropod
genus Purpura: ecological and evolutionary implications. Biol.
Bull. 164:518-535.

YOSHIOKA, P.M. 1982. Predator-induced polymorphism in the
bryozoan Membranipora membranacea (L.). J. Exp. Mar.
Biol. Ecol. 61:233-242.

ZIPSER, E. & G. J. VERMEIJ. 1978. Crushing behavior of
tropical and temperate crabs. J. Exp. Mar. Biol. Ecol. 31:
155-172.

The Veliger 27(4):357-365 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

Gastropod Feeding Tracks as a Source of
Data in Analysis of the
Functional Morphology of Radulae
by

CAROLE S. HICKMAN

Department of Paleontology, University of California, Berkeley, California 94720
AND

TOM E. MORRIS

Department of Life Sciences, Fullerton College, Fullerton, California 92634

Abstract. Feeding tracks produced by the radulae of gastropods are potentially rich sources of data
that (1) can help explain behavior and behavioral variation, (2) provide dietary evidence of the size,
quantity, and specific nature of material that is removed and ingested, and (3) provide detailed evidence
of the ways that natural biological materials fail when grazed.

Analysis of feeding tracks of the intertidal trochid Tegula funebralis (A. Adams, 1854) on artificial
substrates provides standard or idealized sets of impressions of feeding strokes for comparison with sets
of impressions of actual interactions of teeth with materials in the normal diet of the species. Tegula
funebralis feeds in different ways on different substrates by varying the pressure applied to the radula,
with results that vary from deep incisions to light brush marks. Different teeth contact the substrate
during different feeding behaviors, and various forms of asymmetry are common features of feeding
tracks. Feeding tracks can be characterized morphologically on three levels: (1) description of the static
pattern of the track, (2) correlation of the incisions with the teeth that produced them, and (3) dynamic
specification of the order in which individual incisions and groups of incisions are produced relative to
the morphology and movements of the apparatus. The most accurate level of documentation requires

frame-by-frame analysis of filmed feeding sequences of living animals.

INTRODUCTION

MOVEMENT AND FUNCTION of radular teeth and the na-
ture of their interactions with food items and substrates
are among the least well understood aspects of gastropod
feeding. Function cannot be inferred from tooth form alone
(HICKMAN, 1980) or even from correlations of tooth form
and gut contents (HICKMAN, 1981b). In an earlier paper
(Morris & HICKMAN, 1981) we emphasized the impor-
tance of configuration changes in the cylindrical radula of
Tegula funebralis (A. Adams, 1854) in producing a com-
plex sequence of tooth movements during protraction and
retraction. The purpose of this paper is to document the
results of the basic feeding stroke of this rhipidoglossan

trochid gastropod on both artificial and natural substrates
and to show how the stroke can be modified behaviorally
to produce different results. Demonstration that 7. fune-
bralis can use its radula to feed in different ways on dif-
ferent substrates argues for caution in interpreting cor-
relations between tooth morphology and diet. On the other
hand, a wealth of detailed information is available in rad-
ula-marred substrates and prey items, and we hope to
stimulate interest in the morphology of feeding tracks as
a source of functional inference.

Correlations between tooth form and diet are most com-
mon in specialized feeders. Some of the best documenta-
tions in marine gastropods are for Conus (NYBAKKEN, 1970)

Page 358

The Veliger, Vol. 27, No. 4

and “grazing” carnivorous nudibranchs (MCDONALD &
NYBAKKEN, 1978; NYBAKKEN & McDONALD, 1981).
However, the specific nature of radular damage to prey
or interaction with the prey is not understood.

Characterizations of radula-damaged substrates are rare
in the literature. Attention to substrate morphology has
focused primarily on specialized systems, such as the mor-
phology of boreholes produced by active predatory marine
prosobranchs (CARRIKER, 1961, 1977; RADWIN & WELLS,
1968), or characteristic damage to foraminiferal tests pro-
duced by Olivella (HICKMAN & Lipps, 1983). Surfaces of
grazed substrates are the least well known but potentially
rich sources of functional data. The potential is particu-
larly well illustrated by STENECK, who has figured grazing
incisions in crustose coralline algae at the level of cellular
resolution (1982, fig. 5c; 1983, fig. 2) and estimated the
number of epithelial cells consumed per bite by an ac-
maeid limpet (1982:512). However, as in the accounts of
a correlative morphological nature, details of function are
not understood relative to the incisions.

From a sedimentological viewpoint, there has been some
interest in bioerosive damage to calcium carbonate sub-
strates as a by-product of molluscan grazing. Some chitons
and acmaeid limpets excavate shells to feed on boring
algae (GOLUBIC et al., 1975; FARROW & CLOKIE (1979).
The importance of this process is emphasized by FARROW
& CLOKIE (1979) who conclude that molluscan feeding is
a major factor in recycling of carbonate from shells and
in producing carbonate mud in a shallow seaway in Scot-
land.

From the perspective of geologic time, molluscan feed-
ing traces on carbonate substrates have been reported as
far back as the Upper Jurassic (BOEKSCHOTEN, 1967;
VoIGT, 1977). At least some of these fossil grazing traces
seem to be associated with algal-bored substrates (TAYLOR,
1981; AKPAN et al., 1982). Because many of the fossil
traces are closely similar in morphology to modern traces
associated with chitons and acmaeid limpets, functional
and behavioral interpretations should be possible once the
modern traces have been analyzed correctly in functional
terms.

Feeding track morphology has been studied most ex-
tensively by European biologists on aquarium walls or
algal-coated plates (Algen-platten) (HUBENDICK, 1957;
ANKEL, 1938; EIGENBRODT, 1941) and on glass surfaces
coated with wax (Fettplaten) (MARKEL, 1957, 1966). It is
these studies that inspired us to elaborate and extend the
approach to a comparison of artificial surfaces with nat-
ural surfaces and items in the diet of Tegula funebralis.

MATERIALS anpD METHODS

To obtain a baseline description of the zdealized feeding

track (z.e., tooth impressions produced by a single feeding
stroke), it is necessary to have a flat, smooth, fine-grained
surface that will retain three-dimensional impressions. It
also must be a material to which snails are willing to

apply the radula. Experimentation with a variety of wax-
es and preparation techniques led to a procedure using
beeswax (Morris, 1980).

To produce a smooth, shiny surface, melted (60°C) pa-
per-filtered unpurified beeswax (Bee, Inc.) was poured 4
mm thick on cellophane stretched over 2.5-cm high alu-
minum rings supported by upside-down petri dish tops.
After cooling to room temperature, individual beeswax
disks were placed in a freezer for 1 h to harden. Rapid
peeling of the cellophane membrane from the frozen wax
produced a shiny surface.

Tegula funebralis would not graze on new disks, but
feeding tracks were readily obtained on disks that had
been ‘“‘cured” for one week in aerated natural seawater at
7°C. Individual snails were restricted to separate cured
disks in finger bowls covered with porous polyethylene
covers, so that feeding tracks could be correlated with spe-
cific radulae.

After washing grazed disks in distilled water, a great
deal of information can be obtained by examining feeding
tracks on dry disk surfaces with a dissecting microscope
and low-angle reflected light. The illustrations in this pa-
per were obtained with scanning electron microscopy from
portions of disks removed with a hot scalpel, mounted on
SEM stubs, and coated with gold palladium. Scanning
electron microscopy permits resolution of individual tooth
excavations at higher magnifications than are obtainable
with a light microscope.

To obtain comparable observations of the effect of the
feeding stroke on irregular surfaces and natural textures
of the food items in the diet of 7egula funebralis, individ-
uals were allowed to graze in covered finger bowls on
three algal species. Laminaria dentigera, Iridaea splendens,
and the sporophytic rock-encrusting form of Gigartina sp.
(formerly referred to Petrocelis sp.) were chosen to cover
a range of variation in surface texture and topography.
Tegula funebralis has been observed feeding (making the
behavioral motions that indicate protraction and retrac-
tion of the radula) on all three species in the field, as well
as on a variety of other algae (authors’ personal obser-
vations); and BEsT (1964) concluded from experimental
studies that, although 7. funebralis prefers fleshy macro-
algae, it feeds on a variety of encrusting species as well.

Sections of algae with feeding tracks were cut out and
fixed in 2.5% glutaraldehyde, postfixed in 1% osmium
tetroxide, dehydrated through an ethanol series from 50%
to 100%, and critical point dried. Dried specimens were
coated with gold palladium and viewed over the same
range of magnifications as the traces on the beeswax sur-
faces.

RESULTS
Feeding Tracks on Beeswax

Idealized tracks: Typical tracks of Tegula funebralis on
beeswax surfaces are illustrated in Figures 1-8. Each track
is the result of a single feeding stroke or cycle of radular

C. S. Hickman & T. E. Morris, 1985

Page 359

protraction and retraction. During the feeding stroke the
radula behaves as a flat band anteriorly and a slit cylinder
posteriorly, with a movable semicircular crease at the re-
gion of transition that is controlled by the underlying
odontophore. The configuration of the radula at maxi-
mum protraction is illustrated in Figure 9, and the cylin-
drical mode of function is outlined by Morris & HICK-
MAN (1981).

Each trace has two parts and is roughly bilaterally sym-
metrical. In a typical trace the two opposing incised re-
gions are produced exclusively by marginal teeth and are
separated by an untouched central region (Figures 1, 2).
Although the rachidian and lateral teeth are the largest
teeth in the radula, they are recessed between the tips of
the odontophore and do not normally contact flat sub-
strates during the feeding stroke.

The most prominent portions of the trace are the curved
incisions of the individual innermost marginal teeth. Three
or four rows of teeth are involved in the production of
each trace. The sequence of movements is not intuitively
obvious from the morphology of the apparatus, and the
description of trace production is derived from frame-by-
frame analysis of feeding strokes filmed through a micro-
scope on plexiglass surfaces.

Traces in Figures 1-7 are all oriented with anterior at
the top. Note that anterior and posterior correspond to
the positions of the anterior (dorsal) and posterior (ven-
tral) lips of the mouth as it is applied to the substratum.
Thus the anterior end of each trace represents the leading
edge of the direction of locomotion of the snail. In this
usage, anterior and posterior on the trace do not corre-
spond to anterior and posterior on the radula itself. Be-
cause the radula operates as a slit cylinder (Morris &
HICKMAN, 1981), anterior and posterior rows of teeth are
arranged concentrically, so that posterior is in the center
and anterior is at the periphery (Figure 9). As a conse-
quence of this configuration, the anterior end of each trace
is made by the posterior rows of teeth and the posterior
end of each trace by the anterior tooth rows.

The dominant mark in each trace is the single long and
deep incision of the innermost marginal (Figures 1-4).
Adjacent and anterior to the dominant incision is a series
of successively shorter and shallower traces of the remain-
ing five or six inner marginal teeth of the same row (Fig-
ures 1-4). This unit is repeated three to five times by the
rows of inner marginal teeth that contact the substrate
during the feeding stroke.

Figure 10a shows the relative positions and configura-
tion of three marginal tooth rows at the beginning of the
feeding stroke and the travel paths of the inner marginal
teeth. From this diagram it should be clear why the pos-
teriormost row strikes the substrate first to form the an-
teriormost unit of the trace; why the sequence of substrate
contact within a row is from outer to inner marginals;
and, finally, why the innermost dominant incision is the
posteriormost incision in each unit on the substrate.

The path followed by a single row of teeth during the

feeding stroke is illustrated diagrammatically in Figure
10b. Only those portions of the row that pass directly over
the odontophore and make substrate contact are illustrat-
ed. The heavy lines are successive tracings of the position
of the row in sampled frames from 0 to 40 in one filmed
feeding stroke. Zero represents maximum protraction and
40 represents the point at which the row leaves the sub-
strate. Another way to view the same sequence is to follow
the paths of individual teeth or groups of teeth. Figure
10c diagrams the paths of different major blocks of mar-
ginal teeth. Movement is toward the central axis of the
diagram. On such a diagram, we can trace the path of
any individual tooth from the point of initial contact to
the point of lifting from the substrate. These two diagrams
together further help explain why the sequence of contact
of teeth in any given row is from outer to inner marginals
and why the trace records the sequence in an anterior to
posterior direction.

One final set of principles will be helpful in under-
standing the production of the trace. First, it is the inner
marginals that move most directly over the tips of the two
horns of the odontophore as substrate contact is made.
Second, rates of travel vary for different sections of a single
row, and the inner marginals act quickly, in a rapid
“snapping” of the teeth as they flip over the cartilage at
the inner edge of the knickstelle or semicircular crease.
Third, facilitation of inner marginal “snapping” is fur-
thered by the movement of the crease itself as the odon-
tophore is drawn posteriorly during the feeding stroke.
Fourth, the pointed cusps are rotating as they gouge the
substrate to produce U-shaped incisions. Figure 8 is a
low-angle micrograph showing the profiles and relative
depths of incisions.

Variations: In contrast to the typical feeding track de-
scribed above, some feeding tracks are dominated by fine
brush marks of the mid and outer marginal teeth. Unlike
the inner marginals, mid and outer marginal cusps do not
make separate incisions. The upper surfaces of the cusps
act in close concert as they are pressed against a flat sub-
strate and drawn over it. The feeding stroke can be varied
so that only brush marks are produced. Figure 5 shows a
trace with both incisions and brush marks, while Figures
6 and 7 show traces that are dominated by mid and outer
marginal brush marks.

A number of other variations appear in feeding tracks
on the beeswax substrates. The number of rows that con-
tact the substrate is variable (7.e., the number of times that
the basic unit is repeated from anterior to posterior. Fur-
thermore, the number can vary from one side of the trace
to the other, disrupting the bilateral symmetry (Figure 2).
This kind of variation occurs because the right and left
tips of the odontophore act independently and do not nec-
essarily exert the same pressure on the right and left sides
of the radula. Asymmetric traces can be produced in other
ways, some of which are related to underlying patterns of
asymmetry in the morphology itself (HICKMAN, 1981a,

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C. S. Hickman & T. E. Morris, 1985

Page 361

1984), although behavioral asymmetries are more con-
spicuous in feeding tracks. For example, if the tips of the
odontophore do not move synchronously (7.e., if one is
applied to the substrate in advance of the other) a trace
may be produced in which one half will lie anterior to, or
offset from, the other half (Figures 2, 6). Finally, if the
tips of the odontophore do not move straight back (7.e.,
parallel to the plane of symmetry of the idealized trace,
the radula, and the head/foot), a curved trace will be
produced. Figure 6 is a trace that was produced by odon-
tophore tips both moving in parallel arcs. These are the
most common forms of variation, although others occur,
and they can be interpreted from what we know about
tooth morphology, our knowledge of radular function, and
by comparison with the idealized trace.

Feeding Tracks on Natural Substrates

In nature, Tegula funebralis does not graze on beeswax
or plexiglass, nor is it likely to encounter other surfaces
that are perfectly flat and homogeneous. Examination of
feeding tracks on algal surfaces confirms that the radula
is used differently on different food items in the natural
diet of the snails (Figures 11-14).

On the relatively flat blades of the brown alga Lami-
naria dentigera (Figures 11, 12) animals may leave paired
sets of inner marginal incisions similar to those of the
idealized feeding tracks on beeswax. As on the beeswax,
the depth of incision is variable, and the tracks are fre-
quently asymmetric. This type of incision was observed
to release copious cell contents, which are preserved dried
in Figure 11. In this form of feeding, no algal tissue is
removed by the radula.

It would be tempting to conclude that Tegula funebralis
feeds on cell sap of Laminaria. However, animals also
produce much deeper paired excavations on algal blades.
Figure 13 shows an excavated feeding track from which

Figure 9

Optical micrograph of living Tegula funebralis with radula pro-
tracted, from 35-mm negative. Note subcylindrical configuration
with concentrically arrayed tooth rows. Anterior rows on the
radula (A,) are on the outside, while posterior rows (P,) are in
the center. A, denotes anterior lip of the animal; A, denotes
posterior. Arrows show direction of row movement during re-
traction. Bar = 0.5 mm.

a significant volume of algal tissue has been removed. It
does not seem possible that a single feeding stroke could
have produced all this damage to the laminarian blade,
and this may represent a series of feeding strokes “in
place.”

On the irregular blade surfaces of the red alga Jridaea
splendens, feeding traces indicate yet another mode of feed-
ing. Figure 14 shows a surface that has been brushed free
of its attached microbiota with no sign of damage to the
underlying blade. This light brushing of the surface by

Explanation of Figures 1 to 8

Scanning electron micrographs of feeding tracks of Tegula fu-
nebralis on cured beeswax surfaces. Figures 1-7 are oriented
with anterior ends of traces up. Note that in this orientation the
order of trace formation is from top to bottom, with posterior
rows striking the surface first.

Figure 1. Low magnification view of three separate traces, each
produced by a single feeding stroke; M = the center of each trace.
Bar = 1 mm.

Figure 2. Asymmetric feeding track produced by a single feeding
stroke in which the left side is farther anterior and more disor-
ganized due to independent behavior of the two tips of the odon-
tophore. a, b, c = incisions of the innermost marginal teeth of
three successive rows. Compare with Figure 10a for orientation.
Bar = 400 um.

Figure 3. Single feeding track made by inner marginal teeth.
Bar = 400 um. ;

Figure 4. Left half of an asymmetric feeding track with relatively
deep inner marginal incisions. Note that at least 11 inner mar-
ginal teeth in the posteriormost row (anterior or top on the trace)
contacted the substrate. Bar = 400 um.

Figure 5. Feeding track showing both inner marginal incisions
and mid and outer marginal brush marks. Bar = 400 um.

Figure 6. Strongly asymmetric feeding track consisting of mid
and outer marginal brush marks. Bar = 400 um.

Figure 7. Bilaterally symmetric feeding track consisting of light
mid and outer marginal brush marks. Bar = 400 um.

Figure 8. Low-angle side view of left half of feeding track show-
ing incisions of inner marginal teeth. Longest and deepest inci-
sions are those of the innermost marginal; anterior is at right;
individual tooth movement was from top to bottom; and sequence
of incisions is from right and to left. Bar = 100 um.

The Veliger, Vol. 27, No. 4

imm Cc

Figure 10

Dynamics of feeding track production, illustrated from analysis
of 16-mm slow motion (64 frames/sec) film of Tegula funebralis
on wall of plexiglass aquarium. a. Position of three rows at
beginning of feeding stroke (compare with Figure 9). Arrows
show paths of marginal teeth (dominant inner marginal is rep-
resented by large dot); Row 1 (posteriormost on radula) passes
over odontophore and strikes substrate first, followed by rows 2
and 3 (anterior on radula). Solid lines are portions of rows that
make substrate contact. b. Diagram of successive tracings of the
position of a single row over 40 frames in one filmed feeding
stroke. Solid lines show row in contact with substrate; broken
lines show position of retracted portions of rows no longer in

mid and outer marginal teeth is achieved through less-
ening the pressure applied to the radula by the odonto-
phoral cartilage and is comparable to the type of brush
track recorded on beeswax in Figures 6 and 7. This mode
of feeding was also observed in snails feeding on the sur-
face of the crustose sporophytic form of Gigartina spp.
(formerly referred to as Petrocelis franciscana).

DISCUSSION anp CONCLUSIONS

Feeding tracks can be “described” on three levels. The
morphology of the trace can be characterized most simply
as a pattern of marks on the substrate. It also can be
characterized by attributing individual marks to individ-
ual teeth or groups of teeth (a correlation of one static
pattern with another). It can be characterized further at
a dynamic level, as a temporal sequence that specifies the
order in which individual marks and groups of marks are
made relative to the complex ordering of movements of
the radula and odontophore.

The first-order pattern can be described without ref-
erence to its production. The description, however, need
not lack detail: a first-order description at high magnifi-
cation of the ways that cell walls or the underlying bio-
logical materials have failed may contain a great deal of
information. The second order of complexity requires
knowledge of the morphology (and perhaps composition
and structure) of the objects that contact the substrate to
produce the trace. And the third order of complexity re-
quires knowledge of how the morphology moves and works.

The methods and results outlined above provide a guide
to description and analysis at each of the three levels.
They also provide a direct approach to integrated under-
standing of radular functional morphology incorporating
substrate data. It is not clear why so little attention has
been paid to substrate data. Perhaps it is the combination
of the microscopic scale of most feeding traces, their in-
conspicuousness, and the difficulty of observing, preserv-
ing, and collecting them in the field along with the indi-
vidual animals that produced them.

To ignore substrate data, however, is analogous to at-
tempting to analyze what a pencil is used for and how it
functions by examining the pencil and watching someone
manipulating it without ever examining how it is applied
to a piece of paper or what appears on the paper. The
marks on the paper are, in this instance, a particularly
rich source of information about the functional possibili-
ties of a pencil.

The approach that we advocate can be taken much
further than we have taken it here. For example it can be

contact. c. Diagram of paths of movement of major blocks of
teeth in a single row over the same 40-frame sequence depicted
in B. imm = innermost marginal tooth; im = inner marginal
tooth block (teeth producing incisions), and b-g = mid to outer
marginal blocks.

C. S. Hickman & T. E. Morris, 1985

Page 363

Explanation of Figures 11 to 14

Scanning electron micrographs of surfaces of macroalgae after grazing by Tegula funebralis.

Figure 11. Flat surface of Laminaria dentigera with inner marginal incisions and dried cell contents (at posterior

end of each half of the feeding track). Bar = 400 um.

Figure 12. Laminaria dentigera with single, lightly incised feeding trace. Bar = 400 um.

Figure 13. Laminaria dentigera with paired deep excavations and algal tissue removed, probably the result of

multiple feeding strokes in place. Bar = 400 um.

Figure 14. Topographically irregular surface of Iridaea splendens with ungrazed microbiota on right and surface

brushed free of epibionts on left. Bar = 40 um.

extended to include consideration of the biomechanical
properties of radulae and substrates and their interactions.
LITTLER & LITTLER (1980) and STENECK & WATLING
(1982) have suggested that both algae and algal grazers
can be arrayed in “‘functional groups” related to estimated
“toughness” of the alga and estimated “excavating abili-
ties” of the feeding apparatus. Comparative study of rad-
ular morphology, methods of application of radulae to
substrates, and feeding tracks point to major biomechan-
ical difficulties with these predictions. Toughness may be
an important property of some algae relative to some of
the tools that some gastropods apply in some of their feed-
ing behaviors. For other gastropods, other biomechanical
properties of radular teeth and other biomechanical prop-

erties of substrates than toughness may be important. This
is suggested by the radular morphology and composition,
the method of function, and the substrates upon which
some docoglossan limpets feed. Figure 15 illustrates the
feeding tracks of Collisella asm: (Middendorff, 1847) in-
cised in the calcium carbonate shell of its host, Tegula
funebralis. The significant properties of the mineral sub-
strate are its brittleness and hardness relative to the brit-
tleness and hardness of the heavily mineralized radular
teeth. The significant feature of the manner in which this
radula is drawn across the substrate and the linear grooves
that result (Figure 15) is the abrasive mode of removal of
material (which occurs in the gut in finely divided form).
Note that the incisions in Figure 15 are produced parallel

The Veliger, Vol. 27, No. 4

Figure 15

Feeding tracks of Collisella asmi incised in the shell of Tegula
funebralis. Each individual feeding stroke consists of four parallel
grooves produced by abrasion from two inner lateral and two
outer lateral tooth positions. Bar = 100 ym.

to the longitudinal axis of the radular ribbon, in contrast
to the incisions of the radula of 7. funebralis, which are
normal to the axis. Wear patterns of individual docoglos-
san teeth are related to this abrasive mode of feeding
(RUNHAM & THORNTON, 1967; KERTH, 1983) and, con-
trary to most wear patterns, the teeth maintain a sharp,
efficient edge by virtue of use (HICKMAN, 1980).

Aside from applicability to functional morphological
analysis and its biomechanical extensions, feeding track
data can provide better documentation of gastropod feed-
ing biology. Tabulations of dietary preferences of gastro-
pods (see STENECK & WATLING, 1982, appendix 1 and
references therein) are based primarily on observed sub-
strate associations and gut contents. Feeding tracks pro-
vide more reliable and visually compelling estimates of
what animals have actually taken from the substrate—
liquid cell contents, tissue, surface epiphytes, etc. First-
order observations are adequate for dietary documenta-
tion.

A final extension of feeding track analysis is into ex-
perimental ecology and tests of feeding theory. Substrates
can be used experimentally to document and compare pat-
terns of coverage and coverage efficiency, to produce es-
timates of materials removed per unit time, and to ex-
amine patterns of substrate use and partitioning in both
single and multi-species systems.

ACKNOWLEDGMENTS

We thank friends and colleagues who have shared our
enthusiasms for radulae, snails, and snails’ trails and who
have plied us with suggestions and advice; in particular
M. Goodwin for advice on the development of artificial
substrates. C. Schooley and D. Pardoe of the University

of California, Berkeley, Electron Microscope Laboratory,
provided helpful assistance as did J. R. Morgan of the
Scanning Electron Microscope Laboratory, Department
of Anatomy, University of California, San Francisco. The
microcinematography and slow motion analysis were con-
ducted by T. E. Morris, with assistance from R. Tarr,
who loaned the cinematic equipment and D. B. Wake,
who provided access to a motion analyzer. M. E. Taylor
prepared Figure 10. To the anonymous reviewer who ob-
jected to our use of “radulate” as a verb, we extend our
dubious thanks. This work was supported in part by Na-
tional Science Foundation Grants DEB 77-14519 and
DEB 80-20992 to C.S.H.

LITERATURE CITED

AKPAN, E. B., G. E. FARROW & N. Morris. 1982. Limpet
grazing on Cretaceous algal-bored ammonites. Palaeontol-
ogy 25:361-367.

ANKEL, W. E. 1938. Erwerb und Aufnahme der Nahrung bei
den Gastropoden. Verhandl. Deutschen Zool. Gesellsch.
Suppl. 11:223-295.

BEsT, B. 1964. Feeding activities of Tegula funebralis. Veliger
6(suppl.):42-45.

BOEKSCHOTEN, G. J. 1967. Palaeoecology of some Mollusca
from the Tielrode Sands (Pliocene, Belgium). Palaeogeogr.
Palaeoclimatol. Palaeoecol. 3:311-362.

CaRRIKER, M. E. 1961. Comparative functional morphology
of boring mechanisms in gastropods. Amer. Zool. 1:263-
266.

CaRRIKER, M. E. 1977. Ultrastructural evidence that gastro-
pods swallow shell rasped during hole boring. Biol. Bull.
152:325-336.

EIGENBRODT, H. 1941. Untersuchungen tiber die Funktion
der Radula einiger Schnecken. Z. Morphol. Okol. Tiere 37:
735-791.

Farrow, G. E. & J. CLOKIE. 1979. Molluscan grazing of
sublittoral algal-bored shells and the production of carbon-
ate mud in the Firth of Clyde, Scotland. Trans. Roy. Soc.
Edinburgh 70:139-148.

Govusic, S., R. D. Perkins & K. J. Lukas. 1975. Boring
microorganisms and microborings in carbonate substrates.
Pp. 229-259. In: R. W. Frey (ed.), The study of trace fos-
sils. Springer: Berlin.

Hickman, C. S. 1980. Gastropod radulae and the assessment
of form in evolutionary paleontology. Paleobiology 6:276-
294.

Hickman, C. S. 1981a. Evolution and function of asymmetry
in the archaeogastropod radula. Veliger 23:189-194.

Hickman, C. S. 1981b. Selective deposit feeding by the deep-
sea archaeogastropod Bathybembix aeola. Mar. Ecol. Progr.
Ser. 6:339-342.

Hickman, C. S. 1984. Implications of radular tooth-row func-
tional integration for archaeogastropod systematics. Mala-
cologia 25:143-160.

Hickman, C. S. & J. H. Lipps. 1983. Foraminiferivory: se-
lective ingestion of foraminifera and test alterations pro-
duced by the neogastropod Olivella. J. Foram. Res. 13:108-
114.

HuBENDICK, B. 1957. The eating function in Lymnaea stagnalis
(L.). Ark. Zool. 10:511-521.

KERTH, K. 1983. Radulaaparat und Radulabildung der Mol-
lusken. I. Vergleichende Morphologie und Ultrastruktur.

C. S. Hickman & T. E. Morris, 1985

Page 365

Zool. Jb. Anat. 110:205-237; II. Zahnbildung, Abbau und
Radulawachstum. Zool. Jb. Anat. 110:239-269.

LitTLER, M. M. & D. S. LITTLER. 1980. The evolution of
thallus form and survival strategies in benthic marine mac-
roalgae: field and laboratory tests of a functional form mod-
el. Amer. Natur. 116:25-44.

MArRKEL, K. 1957. Bau und Funktion der pulmonaten Radula.
Zeit. Wiss. Zool. 160:213-289.

MARKEL, K. 1966. Uber funktionelle Radulatypen bei Gas-
tropoden unter besonderer Berucksichtigung der Rhipido-
glossa. Vie et Milieu, ser. A, 17:1121-1138.

McDONALD, G. & J. W. NYBAKKEN. 1978. Additional notes
on the food of some California nudibranchs with a summary
of known food habits of California species. Veliger 21:110-
119.

Morris, T. E. 1980. Morphological and functional dynamics
of the rhipidoglossan radula of Tegula funebralis (Mollusca:
Gastropoda). Master’s Thesis, Paleontology, Univ. Calif.,
Berkeley. 145 pp.

Morris, T. E. & C. S. HICKMAN. 1981. A method for artifi-
cially protruding gastropod radulae and a new model of
radula function. Veliger 24:85-90.

NyYBAKKEN, J. W. 1970. Correlation of radula tooth structure
and food habits of three vermivorous species of Conus. Ve-
liger 12:316-318.

NYBAKKEN, J. & G. McDONALD. 1981. Feeding mechanisms
of west American nudibranchs feeding on Bryozoa, Cnidar-
ia and Ascidiacea, with special respect to the radula. Mal-
acologia 20:239-449.

RapDwIn, G. E. & H. W. WELLS. 1968. Comparative radular
morphology and feeding habits of muricid gastropods from
the Gulf of Mexico. Bull. Mar. Sci. 18:72-85.

RUNHAM, N. W. & P. R. THORNTON. 1967. Mechanical wear
of the gastropod radula: a scanning electron microscope study.
J. Zool. (Lond.) 153:445-452.

STENECK, R. S. 1982. A limpet-coralline alga association: ad-
aptations and defenses between a selective herbivore and its
prey. Ecology 63:507-522.

STENECK, R.S. 1983. Escalating herbivory and resulting adap-
tive trends in calcareous algal crusts. Paleobiology 9:44-61.

STENECK, R. S. & L. WaTLING. 1982. Feeding capabilities
and limitation of herbivorous mollusks: a functional group
approach. Mar. Biol. 68:299-319.

Tay.or, P. D. 1981. Bryozoa of British Portland beds (Upper
Jurassic). Paleontology 24:863-875.

VoicT, E. 1977. On grazing traces produced by the radula of
fossil and recent gastropods and chitons. Pp. 335-346. In:
T. P. Crimes & J. C. Harper (eds.), Trace fossils 2. Geol.
J. Spec. Issue 9.

The Veliger 27(4):366-374 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

Predation by Nucella cingulata (Linnaeus, 1771) on

Mussels, Particularly Aulacomya ater (Molina, 1782)

by

PATTI A. WICKENS anp CHARLES L. GRIFFITHS

Zoology Department, University of Cape Town, Rondebosch 7700, South Africa

Abstract.

The whelk Nucella cingulata (Linnaeus, 1771) is abundant in the rocky intertidal zone of

Marcus Island, South Africa, where it feeds on the mussels Aulacomya ater (Molina, 1782), Choromytilus
meridionalis (Krauss, 1848), and Perna perna (Linnaeus, 1758). Aulacomya ater appears to be the
preferred prey. The distribution of boreholes drilled in mussel shells collected from the field appears
to be random, but borehole diameter is an increasing function of prey shell length. Laboratory feeding
experiments confirm that larger individuals of N. cingulata drill wider boreholes and preferentially
select bigger mussels. The energy value of food consumed increases rapidly with predator size, but this
is accomplished by taking progressively larger prey rather than more of them. The overall impact of
N. cingulata on the A. ater population is estimated and compared with that of other invertebrate
predators. Although many small mussels are taken by predators, this often acts merely to reduce the
intense intraspecific competition for space to which juvenile mussels are frequently subjected.

INTRODUCTION

Nucella cingulata (Linnaeus, 1771) is a predatory whelk
that lives in the intertidal and subtidal zones of rocky
shores along the west coast of southern Africa. Its prin-
cipal prey items are the three species of mussel that occur
in the area, namely the ribbed mussel Aulacomya ater
(Molina, 1782), the black mussel Choromytilus meridio-
nalis (Krauss, 1848), and the brown mussel Perna perna
(Linnaeus, 1758). Nucella cingulata attacks its prey by
drilling a hole through the shell, using alternating me-
chanical and chemical processes, 1.e., rasping with the pro-
boscis and secretion of acid by an accessory boring organ
respectively, as described in related species by FRETTER
& GRAHAM (1962). The flesh is subsequently extracted
through the hole using the proboscis and consumed.
Predators utilizing this technique spend most of their
time manipulating and ingesting prey and little in search
and capture. BAYNE & SCULLARD (1978), for example,
found that Nucella lapillus spent between 63 and 97 hours
drilling and ingesting each prey item, and CONNELL (1970)
discovered that Thais spp. spent approximately 70-80%
of their feeding time in the process of drilling alone. Larg-
er mussels naturally yield a greater amount of flesh and
therefore more energy to the predator, but they also have
thicker shells and therefore require a greater investment
of time and energy in the boring process. Consequently,

one might expect each predator to select an optimum size
of mussel, one that provides a balance between energy
gained from the prey flesh and effort put into obtaining
it. Many boring predators do indeed tend to select partic-
ular species and sizes of prey, and many position their
boreholes in certain areas of the shell in order to minimize
the time spent manipulating prey and to maximize the
energy returned per unit effort expended. Such parame-
ters have been studied in a variety of boring gastropods
from different parts of the world. Feeding rates of Poli-
nices duplicatus Say (EDWARDS & HUEBNER, 1977), Nu-
cella lapillus Linnaeus (BAYNE & SCULLARD, 1978), and
Natica tecta Anton (GRIFFITHS, 1981b) have been calcu-
lated, while observations on drilling behavior, borehole
location, and feeding strategies have been made for Lu-
natia aldert (Forbes) (Verlaine, 1936 quoted by FRETTER
& GRAHAM, 1962, and ANSELL, 1960), Nucella lapillus
(MorGan, 1972; HUGHES & DUNKIN, 1984), Natica ca-
tena (da Costa) (NEGuS, 1975), Thais lamellosa Gmelin
(CAREFOOT, 1977), Dicathais aegrota Reeve (BLACK, 1978),
and Natica tecta (GRIFFITHS, 1981b) among others.

The principal objective of this study is to determine
whether Nucella cingulata preferentially select prey by
species or shell length, and if so, to record the prey pref-
erence and consumption rates of predators of various sizes.
Observations are also made of the location of boreholes

P. A. Wickens & C. L. Griffiths, 1985

100

60
20 I
line
0 8 16 24

Shell height (mm)
Figure 1

Number (m7)

Size-frequency distribution of Nucella cingulata on Marcus Is-
land (n = 336). Mean density = 492 + 759 individuals per me-
ter squared.

and relationships between predator and prey size and
borehole diameter. The overall energy requirements of the
predator population are calculated and compared with the
size of the prey resource on Marcus Island. From this,
the effect of N. cingulata on the mussel population can be
determined and the energy requirements of N. cingulata
compared with those of other mussel predators that occur
on the same coast, namely the rock lobster /asus lalandu
(Milne Edwards) (GRIFFITHS & SEIDERER, 1980), the
boring gastropod Natica tecta (GRIFFITHS, 1981b), the
starfish Marthasterias glacialis (Linnaeus) (PENNEY &
GRIFFITHS, 1984), and the African Black Oystercatcher,
Haematopus moquini Bonaparte (HOCKEY, 1984). Finally,
an attempt is made to rate the importance of predation to
other population regulating mechanisms.

METHODS anp RESULTS
FIELD STUDIES

A field survey was conducted during April 1983 when a
total of thirteen quadrat samples was collected from var-
ious tidal levels at each of six study sites on Marcus Is-
land, Saldanha Bay, South Africa (33°02'S, 17°58’E). The
information obtained from each sample included quadrat
area, numbers and size distributions of each of the mussel
species (Aulacomya ater, Choromytilus meridionalis, and
Perna perna), and of the whelk (Nucella cingulata), as well
as shell length, borehole diameter, and borehole position
for drilled shells of each mussel species remaining in the
beds. Data from the thirteen quadrat samples have been
combined here to give a general pattern for Marcus Is-
land. All correlations have been determined using Pear-

Page 367

Aulacomya ater

Choromytilus meridionalis

Log number (m-2)

Perna perna

Shell length (mm)
Figure 2

Size-frequency distributions of live and drilled (shaded area)
Aulacomya ater, Choromytilus meridionalis, and Perna perna on
Marcus Island.

son’s product moment correlation coefficient. Mussel size
is taken as the distance from the umbo to the opposite tip
of the valves. The size of N. cingulata is taken as the
distance from the base of the shell to the top of the last
whorl.

Sizes and Abundances of Predator and Prey and
Quantification of Mussel Predation

A size-frequency distribution for Nucella cingulata from
Marcus Island is shown in Figure 1. The population den-
sity was extremely high and extremely variable at 492 +
759 m~-?. Individual size was small, with a mean shell
height of 9.5 mm. Size-frequency distributions of both
living and drilled Aulacomya ater, Choromytilus meridio-
nalis, and Perna perna are given in Figure 2. Only mussel
species are considered here because a negligible number
of other drilled invertebrate prey, such as the slipper lim-
pet Crepidula porcellana Lamarck, were found. Table 1

Page 368

The Veliger, Vol. 27, No. 4

100

50

Percentage of width

e
e
e es rd e e
fer °° eee eo
ege° woge,ee ¢

100

Percentage of length

Figure 3

Position of 316 boreholes on Aulacomya ater shells collected from Marcus Island.

summarizes the statistics of both living and drilled indi-
viduals of the three mussel species. The population size-
frequency distributions for N. cingulata and all three mus-
sel species are skewed to the right, with the result that the
mean size is higher than the population mode. Aulacomya
ater is the most abundant of the mussel species (64.1%)
and appears to be the preferred prey of N. cingulata (89.2%
of all prey). For all three mussel populations combined,
the mean prey size (16.2 mm) is approximately the same
as the mean population size (15.5 mm), but drilled P.
perna were significantly smaller than the population av-
erage. Nucella cingulata takes similar size ranges of each
prey species, although the mean size of C. meridionalis
taken is slightly greater than that of the other two species.

Location of Boreholes in Shells Collected in the Field

The number of drilled shells of each species and the
number of boreholes per drilled shell are given in Table
2. From the total of 323 drilled mussels recovered, there
were 24 mussels (7.4%) that had more than one borehole
completely penetrating the shell. No Choromytilus meri-
dionalis had more than one borehole, but 7.6% of all drilled
Aulacomya ater and 16.7% of Perna perna had been drilled
more than once. The position of the borehole on each
drilled shell for each of the three species was plotted as
the percentage of the shell length against the percentage
of the shell width. For C. meridionalis and P. perna, there
were too few borehole data (n = 23 and n= 14 respec-

Table 1

Population statistics for living and drilled Aulacomya ater, Choromytilus meridionalis, and Perna perna on Marcus Island.

Living populations

Percent-
Density age of all Mean length
Species (m-?) mussels (mm)
Aulacomya ater 28,528 64.1 13.0 + 6.6
+ 33,086
Choromytilus 3593 8.1 22 1220
meridionalis + 1823
Perna perna 12,356 27.8 19.3 + 12.6
+ 9738
Total 44,477 100.0 15.5

Size

Drilled
Drilled shells shellsas
percent-
Percent- Size ages of
range Density age of all Mean length range their pop-
(mm) (m7?) mussels (mm) (mm) ulations
1-42 487 89.2 15.7 + 6.6 3-40 1.74
1-62 16 7.1 21.8 + 10.2 7-46 0.46
1-72 62 37, 122352 el 3-32 0.30

P. A. Wickens & C. L. Griffiths, 1985

1,4

=
‘o)

Borehole diameter (mm)
Oo
ron)

©
N

6) 8 16

Page 369

24 32 40 48

Mussel shell length (mm)

Figure 4

Borehole diameter as a function of mussel shell length for 353 boreholes drilled into all three mussel species
collected from Marcus Island. For convenience, a mean value of each 2-mm size class is represented with vertical
bars showing one standard deviation either side of this mean.

tively) to show an aggregation in any particular region.
Figure 3 shows the borehole positions for A. ater. Al-
though the margins of the shell valve are avoided, there
does not appear to be a concentration of boreholes in any
particular locality. Of the drilled shells of all three species,
48.6% were drilled on the left valve while 51.4% were
drilled on the right valve. A chi-square test showed that
this difference was not significant (n = 353, 0.05 < P<
0.01).

Borehole Diameter versus Mussel Size

In order to ascertain whether larger mussels had been
preyed upon by larger Nucella cingulata, borehole diam-
eter was measured and related to the shell length of each
drilled mussel. Both outside and inside borehole diameters
were measured, but the outside measurement was ulti-
mately used as the standard index of size. Boreholes were
measured using a dissecting microscope fitted with a net-
scale graduated to 0.1 mm and a mean value calculated
for mussels of each 2-mm size class from 3-4 mm to 45-
46 mm. Figure 4 shows a plot of mean outside borehole
diameter for each 2-mm size class against mussel length.
The inside borehole diameter varies less with increasing
mussel size, having a slope with half the gradient of that
for outside diameter. The correlation between borehole
diameter and mussel size is significant (n = 323, 0.025 <
P < 0.005), and a regression line fitted to the data gives

the relationship: borehole diameter (mm) = 0.323 +
0.015 xX mussel length (mm) (7 = 0.918).

LABORATORY STUDIES

Because Aulacomya ater appeared to be the most abundant
prey species taken by Nucella cingulata, only this species
was considered in our experimental studies. Specimens of
N. cingulata and A. ater were collected from Marcus Is-
land and taken to the laboratory, where prey size-selection
and predation-rate experiments were conducted. The an-

Table 2

Number of boreholes found in shells of Aulacomya ater,
Choromytilus meridionalis, and Perna perna collected from
Marcus Island.

Total
Total number
number of

Number of holes in shell sino ESTES

Species 1 2 oe 4 oe holes shells

Aulacomya ater 266) 185 3) 0) el 316 288
Choromytilus

meridionalis 23 0 0 O 23 23
Perna perna 10 2. 14 12

Total ZY BD. O. 1 353 323

oo
on)
(=)

Page 370

—
O

0,2

Borehole diameter (mm)
{o)
ron)

2 6 10

The Veliger, Vol. 27, No. 4

14 18 22

Nucella cingulata height (mm)

Figure 5

Borehole diameter as a function of Nucella cingulata height for 78 boreholes drilled into Aulacomya ater shells in
the laboratory. For convenience, a mean value for each 2-mm size class is represented here with vertical bars

showing one standard deviation on either side of this mean.

imals were maintained in large aquaria connected to a
flow-through seawater system at a constant temperature
of 14.5°C (which is approximately the temperature of the
seawater at Marcus Island). An acclimation period of 15
days was allowed during which time the specimens of N.
cingulata were supplied with excess A. ater of a wide size
range. The whelks (n = 33) were then separated into sev-
en 3-mm size classes (3-5 mm to 21-23 mm), each group
being placed in a separate plastic floating ring with a net
base and floated in a large tank. In two of the size classes
of N. cingulata only a few individuals were available, so
not all of the rings were initially supplied with the same
number of individuals. The specimens of A. ater were also
separated into eight 5-mm size classes (1-5 mm to 36-40
mm) and each of the seven rings supplied with six indi-
viduals from each size class of mussel.

The tanks were subsequently examined every 4 days
for a total period of 32 days. At each sampling all the
drilled mussels were removed and measured and replaced
with other individuals from the same size class. Any dead
individuals of N. cingulata were also removed and, where
possible, replaced with other individuals from the same
size class. Additional specimens of N. cingulata were kept
in a separate tank and were fed Aulacomya ater to sustain
them, so that they would not be starved if needed in the
experiments. Because the number of predators per size
class during each 4-day sampling period was not constant,
the consumption rate per N. cingulata was calculated in-
dependently over each 4-day period and subsequently av-
eraged.

Location of Boreholes in Shells
Collected in the Laboratory

No shell with more than one complete borehole was
found during the laboratory experiments. The positions
of the boreholes were similar to those in shells recovered
from the field. Of the drilled shells, 42.3% were drilled
on the left valve and 57.7% on the right valve. A chi-
square test showed that this difference was not significant
(n = 78, 0.05 < P < 0.01).

Borehole Diameter versus Nucella cingulata Size

The mean outside and inside borehole diameters were
calculated for Aulacomya ater shells drilled by Nucella cin-
gulata of each of the size classes. The slope for inside
diameter against N. cingulata size was again half that for
outside diameter. A plot of mean outside borehole diam-
eter against N. cingulata size is given in Figure 5. The
correlation between borehole diameter and N. cingulata
size is significant (n = 78, 0.025 < P< 0.005), and a
regression line fitted to the data produced the relationship:
borehole diameter (mm) = 0.281 + 0.03 x N. cingulata
height (mm) (7 = 0.980).

Drilled Aulacomya ater Size versus
Nucella cingulata Size

The mean size of Aulacomya ater drilled by Nucella
cingulata of each 3-mm size class is shown in Figure 6.
The correlation between N. cingulata size and shell length

SS

P. A. Wickens & C. L. Griffiths, 1985

Page 371

22

Aulacomya ater length (mm)

2 6 10

14 18 22

Nucella cingulata height (mm)

Figure 6

Length of 78 Aulacomya ater consumed in a laboratory experiment as a function of Nucella cingulata height. For
convenience, a mean value for each 2-mm size class is represented here with vertical bars showing one standard

deviation on either side of this mean.

of prey taken is significant (n = 78, 0.025 < P < 0.005),
and a regression line fitted to the data produced the re-
lationship: A. ater length (mm) = 3.632 + 0.734 x N. cin-
gulata height (mm) (7 = 0.978).

Predation Rate

Number of prey consumed: For each Nucella cingulata
size class, the number of Aulacomya ater consumed per
individual per day was calculated (Table 3). The mean
consumption rate was 0.08 + 0.035, but there was no
apparent relationship between the number of prey con-
sumed per day and predator size.

Energy consumption: The dry flesh weights of different
sized specimens of Aulacomya ater (5-25 mm) were mea-
sured, and the energy value of the flesh was determined
by bomb calorimetry. The relationship between A. ater
dry weight and size is significant (n = 90, 0.025 < P <
0.005), the relationships being: (1) A. ater dry weight (mg)
= 0.025 x A. ater length (mm)??** (7 = 0.889) and (2) A.
ater energy value = 18.27 + 0.95 kJ/g dry weight.
Because no flesh appeared to remain behind in the dis-
carded mussel shells, it was assumed that Nucella cingulata
ingests its prey with 100% efficiency. Contrary results
have been found in, for example, Polinices duplicatus, which
consumes only the visceral portion of the clam Mya ar-
enaria Linnaeus (EDWARDS & HUEBNER, 1977), and we

recognize that there is likely to be loss of some semiliquid
material (e.g., DAGG, 1974); however, we were unable to
quantify this. Thus, for each size class of N. cingulata, all
the Aulacomya ater drilled in each of the eight 4-day sam-
pling periods were converted to energy equivalents, and
the total amount of energy consumed per predator in each
4-day period was calculated. These values were then
summed to give the total energy consumed per N. cingulata
over the 32 days and converted to weekly energy values.
A plot of energy consumed per N. cingulata per week

Table 3

Number of Aulacomya ater consumed per Nucella cingu-
lata individual per day in laboratory experiments.

Number of Aulacomya ater

Nucella cingulata size class consumed per individual

(mm) per day
3-5 0.07
6-8 0.12
9-11 0.11
12-14 0.10
15=17. 0.02
18-20 0.07
21-23 0.05
Mean + 1 SD 0.08 + 0.035

Page 372

300

200

100

Energy consumption
(kJ.individual-'. week~")

0)
6) 8 16 24

Nucella cingulata height (mm)
Figure 7

Average weekly energy consumption of Nucella cingulata during
the laboratory experiments as a function of shell height.

against N. cingulata height is shown in Figure 7. One N.
cingulata size class yielded only two data points and this
group was excluded from the analysis. The correlation
between mean energy consumption per week and N. cin-

40

ié)
oO

NO
oO

(individual"'.day-')

=
(eo)

Percentage body energy consumption

°5 8 16 24

Nucella cingulata height (mm)

Figure 8

Percentage body energy consumption per Nucella cingulata in-
dividual per day as a function of shell height.

The Veliger, Vol. 27, No. 4

gulata size is significant (n = 6, 0.025 < P < 0.005), and
regression of the data produced a power curve with the
relationship: energy consumption (kJ/week) = 1.187 x
10-2 x N. cingulata height (mm)°** (7 = 0.967).

Percentage body energy consumed by Nucella cingu-
lata: The dry weights of different sized specimens of Nu-
cella cingulata (6-25 mm) were measured, and the energy
value of the flesh was determined by bomb calorimetry.
The correlation between N. cingulata dry weight and size
is significant (n = 29, 0.025 < P < 0.005), the relation-
ships being: (1) N. cingulata dry weight (mg) = 0.012 x
N. cingulata height (mm)?°” (7 = 0.984), and (2) N. cin-
gulata energy value = 20.52 + 0.04 kJ/g dry weight.
From these equations, the energy values of N. cingulata
of different sizes were calculated. Using the daily con-
sumption rates in conjunction with the energy values of
N. cingulata, the percentage body energy consumed per
day for different sized specimens of N. cingulata was ob-
tained. A plot of percentage body energy consumed per
day by different sized N. cingulata is given in Figure 8.
The correlation between percentage body energy con-
sumed and N. cingulata size is significant (n = 6, 0.025 <
P < 0.005), and fits a power curve with the relationship:
percentage body energy consumed per individual per day =
5.263 x 10? x N. cingulata height (mm)~'*!? (r = —0.996).

DISCUSSION
Prey Selection

Our field surveys showed that Nucella cingulata preys
upon all three of the mussel species present on Marcus
Island. Aulacomya ater appears to be the preferred prey
because it comprises 64% of the living mussel community,
but makes up 89% of the natural diet of N. cingulata (as
indicated by numbers of drilled shells found in the field).
There are several possible reasons for this preference for
A. ater. It may be selected simply because it is the most
abundant and hence most easily located prey species. The
tidal level at which N. cingulata is most abundant is that
at which A. ater is most dense. This may be because of
similar tolerance of the two species to exposure, rather
than simply an aggregation of predators in the region of
maximum prey availability. One factor that certainly con-
tributes to the greater vulnerability of A. ater is that the
population consists almost entirely of small individuals
(<40 mm) that fall within the size range available as prey
to N. cingulata (3-46 mm). By contrast, many of the spec-
imens of Choromytilus meridionalis and Perna perna exist
in a “refuge in size” (PAINE, 1965) over 46 mm, where
they are not available to the small individuals of N. czn-
gulata that dominate the population in this area. There is
no doubt, however, that there is a definite preference for
A. ater even within the available size range as prey, as can
be seen from Figure 2.

Laboratory experiments showed that the size of prey
taken by individual Nucella cingulata is an increasing func-

P. A. Wickens & C. L. Griffiths, 1985

tion of predator size (Figure 6), a finding that is confirmed
by studies of other boring gastropods, such as Nucella
lapillus (BAYNE & SCULLARD, 1978) and Polinices dupli-
catus (EDWARDS & HUEBNER, 1977). The size of preda-
tors can also be inferred from borehole diameter (Figure
5), so our laboratory results could be validated in the field
by correlating borehole diameter with length of drilled
mussels. Field surveys indeed confirmed that larger mus-
sels had, on average, wider boreholes (Figure 4) and, hence,
had been preyed upon by larger predators.

Location of Boreholes

Some boring gastropods selectively drill in a particular
location of the prey shell. CAREFOOT (1977), for example,
calculated that 98% of the boreholes drilled by Thazvs la-
mellosa on Mytilus edulis were found in the thinner regions
of the prey shell, whereas HUGHES & DUNKIN (1984) found
that Nucella lapillus reduced drilling time by approxi-
mately 27% by drilling through the thinnest areas of the
shell. GRIFFITHS (1981b) found that the position of the
boreholes drilled by Natica tecta on Choromytilus meri-
dionalis were related to the way in which the predator
holds its prey. MORGAN (1972) showed that the boreholes
on Cerastoderma edule drilled by Nucella lapillus were de-
termined by the way the cockle is held in the sand. Thais
lamellosa (CAREFOOT, 1977), Lunatia alderi (Verlaine, 1936
quoted by FRETTER & GRAHAM, 1962), Dicathais aegrota
(BLACK, 1978), and Nucella lapillus (HUGHES & DUNKIN,
1984) have been shown to drill boreholes over particular
underlying organs. However, the boreholes drilled by Nu-
cella cingulata appear to be randomly located over the en-
tire central portion of the shell, with no preference for
either valve. Several Nucella lapillus individuals have been
observed to feed simultaneously on a single prey item
(MorGan, 1972; BAYNE & SCULLARD, 1978). Because
7.4% of all mussels drilled by N. cingulata on Marcus
Island have more than one hole, it is possible that this
may have resulted from a cluster of individuals feeding at
the same time. Alternatively, some N. cingulata may, in
error, drill into a mussel that has already been eaten,
particularly if the mussel has not opened because of in-
complete ingestion of the adductor muscle by the original
attacker.

Predation Rate

The number of Aulacomya ater individuals consumed
by Nucella cingulata shows no increase with predator size,
the increased consumption rates of larger predators being
attained by eating larger prey, rather than by taking more
of them. Energy consumption is an approximately linear
function of N. cingulata height (power value of 0.98). This
is in contrast to the findings for Natica tecta, where energy
consumption is approximately a cubic (power value of
2.9132) function of shell height (GRIFFITHS, 1981b). The
two shells are, however, quite different in shape, Natica
tecta having a more spherical shape and presumably in-

Page 373

creasing in weight more rapidly with shell height. Nucella
cingulata consumption, moreover, declines drastically from
about 40.0 to 1.5% of body energy per day with increasing
size, over the range of 3 to 23 mm (Figure 8). By com-
parison, BAYNE & SCULLARD (1978) showed that Nucella
lapillus consumes between 15 and 1.5% of its body weight
per day over a size range of 12 to 32 mm, while Polinices
duplicatus consumes between 1.3 and 0.9% of its body
weight per day over a size range of 19 to 45 mm (ED-
WARDS & HUEBNER, 1977). The lower limits of the per-
centage body energy/weight consumed for the larger an-
imals of these different species are comparable, while the
smaller specimens of N. cingulata take a greater percent-
age, as might be expected as a result of their higher weight-
specific metabolic rate.

Exploitation of Aulacomya ater on Marcus Island

Using our laboratory relationship between energy con-
sumption and size of Nucella cingulata, together with its
size-frequency distribution and density on Marcus Island,
the energy requirement of the entire population can be
calculated as 3475 kJ-m~?-yr~'. The standing crop of the
entire Aulacomya ater population was 7939 kJ-m~?, while
the energy available from individuals in size classes ac-
cessible to N. cingulata is 7437 kJ-m~? (94% of the total).
It is of interest to compare this predation rate with those
of other mussel predators that occur in the same area.
Aulacomya ater comprises only 16% of the diet of the Af-
rican Black Oystercatcher, Haematopus moquini, on Mar-
cus Island and its total annual take of mussels is estimated
to be a relatively moderate 878 k]J-m~?-yr~' (HOCKEY,
1984, and unpublished data). Three invertebrate preda-
tors, the rock lobster Jasus lalandi, the starfish Marthas-
terias glacialis, and the gastropod Natica tecta have also
been studied. In their areas of maximal abundance and
when feeding on the mussel Choromytilus meridionalis, these
were predicted to consume annual totals of 5835 kJ-m~?,
6028 kJ-m~? and 9010 kJ-:m~? respectively (PENNEY &
GRIFFITHS, 1984). Populations of C. meridionalis, how-
ever, have a greater standing crop (19,125-21,675 kJ-
m_~?) than those of A. ater, so that the percentage of stand-
ing crop taken in each case is remarkably similar, at 46%
for N. cingulata consuming A. ater and between 28 and
44% for the three predators of C. meridionalis.

Although we recognize that laboratory feeding experi-
ments may substantially overestimate consumption rates,
the predation pressure exerted by each of these predators
is nevertheless considerable and, if there were no mussel
replacement, they would rapidly obliterate their prey pop-
ulations. In reality, however, each species has been studied
in its area of maximum abundance and there is only par-
tial overlap in the distributions of the various species.
Therefore, where one predator is particularly abundant,
the others are often rare or absent, and where two or more
predators are present, they frequently both occur at re-
duced densities. Nonetheless, our results suggest that pre-

Page 374

The Veliger, Vol. 27, No. 4

dation rates of 30-50% of prey standing stock per annum
are commonplace and these would significantly affect the
density and size composition of the mussel beds, particu-
larly because the majority of prey are taken from a par-
ticular “window” of size classes available to the predators.

If we consider the overall impact of predation on set-
tlements of mussels, however, we must remember that
juvenile mussel populations have an extremely high pro-
duction-to-biomass (P/B) ratio which allows them to sup-
port considerable predation pressure without any decline
in standing crop. In Aulacomya ater, for example, the P/
B ratio is 29.5 at 5 mm (all of which goes into growth),
declining below 2.0 above 45 mm (most of which is ex-
pended in reproductive output) (GRIFFITHS & KING, 1979).
Secondly, GRIFFITHS (1981a) has shown that juvenile
Choromytilus meridionalis normally settle at densities of
some tens of thousands of individuals per square meter,
whereas the maximum packing density of adults over 50
mm is of the order of one thousand per square meter.
These figures may not be directly applicable to A. ater,
which can form multilayered beds, but a mortality of 90%
or more is still to be expected over this growth period and
will be accomplished by intraspecific competition for space
should there be little or no mortality through predation.

Populations of juvenile mussels can thus absorb consid-
erable losses to predation while remaining at maximum
population density in terms of substrate carrying capacity.
The actual rate of loss that can be tolerated while main-
taining 100% cover will vary with the growth rate, but
will probably be at least equal to the standing crop, be-
cause the P/B ratio of mussels of the size range available
to predators is at least two. It is interesting to note that
at the point where mussels grow into a “refuge in size,”
when they are no longer available to the majority of pred-
ators, they almost simultaneously arrive at a stable pack-
ing density at which they can continue to grow in length
while fitting into the same area of substrate (see GRIF-
FITHS, 1981a, fig. 7).

In conclusion then, it appears that dense settlements of
juvenile mussels can support large populations of preda-
tors during their logarithmic growth phase, while main-
taining complete substrate coverage and constant or even
increasing biomass and reproductive output (GRIFFITHS,
1981a). The slowing of growth rate that occurs as adult
size is approached is accompanied by reductions both in
the intensity of competition for space and in predation
pressure, because the mussels reach a size at which they
are relatively immune to predators. These adult popula-
tions persist until they become senile and die or are elim-
inated by some natural catastrophe, which may often take
the form of a massive settlement of their own spat (GRIF-
FITHS, 1981a).

ACKNOWLEDGMENTS

The authors would like to thank all those who helped
collect and sort material on Marcus Island, as well as
Diana Gianakouras, who assisted with the bomb calorim-

etry. Financial support for the work was provided through
the Benguela Ecology Program of the South African
Council for Scientific and Industrial Research and a CSIR
postgraduate bursary to the senior author. A grant toward
the costs of publication was provided by the Editorial Board
of the University of Cape Town.

LITERATURE CITED

ANSELL, A. D. 1960. Observations on predation of Venus stria-
tula (da Costa) by Natica alderi (Forbes). Proc. Malacol.
Soc. Lond. 34(3):157-164.

BayNE, B. L. & C. SCULLARD. 1978. Rates of feeding by Thais
(Nucella) lapillus (L.). J. Exp. Mar. Biol. Ecol. 32:113-
129.

BERRY, P. F. 1978. Reproduction, growth and production in
the mussel, Perna perna (Linnaeus), on the east coast of
South Africa. S. Afr. Assoc. Mar. Biol. Res. 48:1-28.

BLack, R. 1978. Tactics of whelks preying on limpets. Mar.
Biol. 46:157-162.

CaREFOOT, T. 1977. Pacific seashores. A guide to intertidal
ecology. Univ. of Washington Press: Vancouver. 208 pp.

ConneELL, J. H. 1970. A predator-prey system in the marine
intertidal region. I. Balanus glandula and several predatory
species of Thais. Ecol. Monogr. 40:49-78.

Daca, M. J. 1974. Loss of prey body contents during feeding
by an aquatic predator. Ecology 55:903-906.

Day, J. H. 1974. A guide to marine life on South African
shores. 2nd ed. A. A. Balkema: Cape Town. 300 pp.
Epwarbs, D.C. & J.D. HUEBNER. 1977. Feeding and growth
rates of Polinices duplicatus preying on Mya arenaria at
Barnstable Harbour, Massachusetts. Ecology 58:1218-1236.

FRETTER, V. & A. GRAHAM. 1962. British prosobranch mol-
luscs. Their functional anatomy and ecology. Ray Society:
London. 755 pp.

GRIFFITHS, C. L. & J. L. SEIDERER. 1980. Rock-lobsters and
mussels—limitations and preferences in a predatory-prey
interaction. J. Exp. Mar. Biol. Ecol. 44:95-109.

GRIFFITHS, C. L. & J. A. Kinc. 1979. Energy expended on
growth and gonad output in the ribbed mussel Aulacomya
ater. Mar. Biol. 53:217-222. ji

GRIFFITHS, R. J. 1981a. Population dynamics and growth of
the bivalve Choromytilus meridionalis (Kr.) at different tidal
levels. Estuarine Coastal Shelf Sci. 12:101-118.

GRIFFITHS, R. J. 1981b. Predation on the bivalve Choromytilus
meridionalis (Kr.) by the gastropod Natica (tectonatica) tecta
Anton. J. Moll. Stud. 47:112-120.

Hockey, P. A. R. 1984. Growth and energetics of the African
Black Oystercatcher Haematopus moquini. Ardea 72:111-
ALIVE

HuGuHEs, R. N. & S. DEB. DUNKIN. 1984. Behavioural com-
ponents of prey selection by dogwhelks, Nucella lapillus (L.)
feeding on mussels, Mytilus edulis L., in the laboratory. J.
Exp. Mar. Biol. Ecol. 77:45-68.

MorGan, P. R. 1972. Nucella lapillus (L.) as a predator of
edible cockles. J. Exp. Mar. Biol. Ecol. 8:45-52.

Necus, M. 1975. An analysis of boreholes drilled by Natzca
catena (da Costa) in the valves of Donax vittatus (da Costa).
Proc. Malacol. Soc. Lond. 41:353-356.

PaInE, R. T. 1965. Natural history, limiting factors and en-
ergetics of the opisthobranch Navanax inermis. Ecology 46:
603-619.

PENNEY, A. L. & C. L. GrirFiTHs. 1984. Prey selection and
the impact of the starfish Marthasterias glacialis (L.) and
other predators on the mussel Choromytilus meridionalis
(Krauss). J. Exp. Mar. Biol. Ecol. 74:19-36.

The Veliger 27(4):375-380 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

The Activity Pattern of Onchidella binneyi

Stearns (Mollusca: Opisthobranchia)

by

PHILIP J. PEPE anp SUEANNE M. PEPE

Center for the Study of Deserts and Oceans, P.O. Box 53, Puerto Penasco, Sonora, Mexico

Abstract.

Onchidella binney: inhabits the upper intertidal zone on rocky shores of the Gulf of Cal-

ifornia. At El Bajo, B.C.S., Mexico, the activity of a population of O. binney: followed a distinct pattern.
The nightly activity period began shortly after the ebbing tide exposed the animals’ position on the
shore. The number of active animals increased steadily to a maximum and then declined until all

activity ceased during the hour of low tide.

The activity cycles of Onchidella binney: were synchronous with the tides. The maximum number of
animals active each night was inversely correlated with the tidal height at low tide. At neap tides the
O. binney: population was inactive. At spring tides the intensity of activity reached a maximum. °

Animals were held in aquaria in a non-tidal simulation. They continued to exhibit daily activity
very similar to the field population. This indicates that either the population is directly cued by some
environmental factor that fluctuates in relationship to the tides, or that Onchidella binneyi possesses an

internal biological clock.

INTRODUCTION

Onchidella is a small genus of opisthobranchs that has a
wide geographical distribution. Members of this genus are
completely shell-less as adults, with papillate mantles and
lungs (WaTSON, 1925; FRETTER, 1943). Their mantle
margins contain repugnatorial glands whose secretions are
effective against a wide range of possible predators in-
cluding crabs and fish (AREY & CROZIER, 1921; WATSON,
1925; IRELAND & FAULKNER, 1978). Onchidella inhabits
rocky shores, living in eroded cavities or clefts between
stones (AREY & CROZIER, 1921; WATSON, 1925; FRET-
TER, 1943; Marcus & Marcus, 1956). With few excep-
tions, species of Onchidella have been reported only from
the intertidal zone.

Activity patterns synchronous with ocean tides have been
reported for four species of Onchidella: O. verruculatum
Cuvier (H1RASKA, 1912), O. floridanum (Dall) (AREY &
CROZIER, 1921), O. celtica (Forbes & Hanley) (FRETTER,
1943), and O. indolens (Gould) (Marcus & Marcus,
1956). In each case animals were observed crawling about
on the top surfaces of rocks during daytime ebbing tides
only. During other tidal stages, they were not observed
on the surface of the rocks but were found inactive within
rock cavities.

AREY & CROZIER (1921) observed Onchidella florida-

num on Bermuda shores and reported a diurnal activity
pattern for this species. Onchidella floridanum emerged from
its rock shelters only after the falling tide had left it ex-
posed to the air for approximately one hour. Individuals
were observed actively grazing diatoms on the rock sur-
faces for an additional hour. After the grazing period, the
animals simultaneously returned to their shelters. All an-
imals had disappeared from the top surfaces of rocks be-
fore low tide.

Onchidella binneyi Stearns, 1893, a dark gray slug ap-
proximately 2.5 cm long, is endemic to the Gulf of Cali-
fornia. Preliminary observations in May 1978 indicated
that O. binneyi, although active only at night, had an ac-
tivity pattern similar to that of O. floridanum. A study was
designed to determine whether the activity of a population
of O. binney: was synchronous with ocean tides and whether
the behavior would persist if animals were left in standing
seawater in aquaria.

STUDY AREA

The study area was located at El Bajo, 10 km north of
Loreto, Baja California Sur, Mexico, on the shore of the
central region of the Gulf of California. At El Bajo the
upper intertidal zone consists of densely packed basalt
boulders and shingles over a sand base. The beach slopes

Page 376 The Veliger, Vol. 27, No. 4
200
3 150
LW
2
FE 100
O
C= ¢ Site Site
uncovered covered
rt
rae} 50
=
=)
4
0) i 2 3 4 5 6 7
TIME (hrs)

Figure 1

The mean number of active animals during 25 nights of activity for the Onchidella binneyi population at El Bajo,
B.C.S., Mexico. The bars represent the standard errors of the mean. The arrows indicate the average time of the
animals’ exposure to the air and the average time of low tide relative to the activity of the population.

about 4° seaward. Onchidella binneyi lives in a narrow
zone buried beneath the stones. This zone is located at a
tidal height of approximately 0.8 m above mean lower
low water (MLLW). El Bajo is protected from storm
surge by a nearby offshore island, Isla Coronado.

The central region of the Gulf of California has mixed
semi-diurnal tides that change to a diurnal pattern during
the neap portion of a tidal series. At E] Bajo the maximum
tidal range is approximately 1.4 m. The tides at El Bajo
match the NOAA predictions for Guaymas, Sonora, Mex-
ico.

Onchidella binneyi lives just below mean sea level (MSL),
or the break between the high and middle intertidal zones
as defined by RICKETTS & CALVIN (1939). Therefore, the
population experiences one or occasionally two aerial ex-
posures per day during the spring portions of a tidal se-
ries, and zero or one exposure per day during the neap
portions.

METHODS

At El Bajo, the Onchidella binneyi population is restricted
to a 2-m wide strip parallel to the drift line. A 20-m long
section of this strip was marked for observation. To avoid
disturbing the animals’ natural activities, the area was
studied from its perimeters only, and animals were never
removed from it. Observations were made from 5 to 21
August 1978 and from 10 to 24 May 1979.

Specimens of Onchidella binneyi observed on the tops
and sides of rocks were considered active (WELLS [1980]
followed a similar definition for limpets). The number of

active animals was recorded every 30 min. Counts were
begun when the falling tide first uncovered the marked
area and were continued until animals were no longer
observed on rock surfaces. The tidal height and time of
low tide were also recorded. Nighttime observations were
made using flashlights. Two independent counts were
conducted simultaneously to ensure accuracy. A light-dark
preference experiment showed that the slugs’ movements
were not affected by the flashlights.

A set of experiments was run from 13 to 19 May 1979
to determine whether the activity pattern would persist if
the animals were left submerged in seawater. Three 1-L
jars (16 cm tall) with screen tops were used as aquaria.
Ten specimens of Onchidella binneyi: were placed in each
jar and the jars were filled with seawater to within 4 cm
of the top. The water was partially changed each day but
never totally drained, thus simulating a non-tidal condi-
tion. The aquaria were shaded from the sun. The number
of active slugs and the time of activity were recorded pe-
riodically for the experimental and field populations si-
multaneously.

RESULTS
Behavior Synchronous with the Tides

Onchidella binneyi was active only at night when ex-
posed to the air. During these activity periods the animals
had a particular appearance: their mantle margins were
lifted above the substrate; their eyestalks were extended
and their oral lobes were swept from side to side; and

P. J. Pepe & S. M. Pepe, 1985 Page 377

TIDAL HEIGHT

FIELD

AUGUST 1978

TIDAL HEIGHT

FIELD

AQUARIA

16
MAY 1979

Figure 2

The intensity of nightly activity (maximum number active) is compared with the tidal amplitudes (NOAA predic-
tions for Guaymas, Mexico) and the lunar phases for each census period. The August and May graphs both report
data for the field population (closed circles). Each point represents a single night’s maximum count. The May
graph reports data for the experimental population in the aquaria (open circles). Each experimental point represents
the mean of three replicates and includes standard error bars. The horizontal dotted lines through the tidal
amplitudes depict the tidal height of the animals’ position on the shore.

The Veliger, Vol. 27, No. 4

300

200

INTENSITY OF ACTIVITY (field)

TIDAL HEIGHT AT LOW TIDE
Figure 3

The relationship between the intensity of activity (maximum
number active) in the field population and the predicted tidal
height at low tide. Each point represents one night of the census
period. Regression lines are fitted to the data points for each of
three tidal series. August 5 to 10, 1978 (part of a new moon
tidal series) is depicted with open circles and a dotted line (7? =
0.98). August 11 to 21, 1978 (part of a full moon tidal series) is
depicted with closed circles and a solid line (7? = 0.77). May 11
to 19, 1979 (part of a full moon tidal series) is depicted with
crosses and a dashed line (7? = 0.72).

their dorsal surfaces were flat and mantle papillae were
retracted. Activities included grazing on diatom films, cop-
ulating, and moving about at an average speed of 2 cm/
min (determined by measuring the distance covered dur-
ing 1 h for 10 animals).

During the active periods, individual animals were ob-
served on the upper surfaces of the rocks for durations of
from 1 min to over an hour. The animals did not emerge
or retreat simultaneously. Instead animals moved between
active and inactive portions of the population.

The number of animals active on the surface followed
a particular pattern each night. The active period began
shortly after the ebbing tide uncovered the study area. The
number of animals on the surface increased steadily to a
maximum and then declined until all activity ceased dur-
ing the hour of low tide (Figure 1).

The time of the active period progressed during a tidal
series in the same manner as the tides (approximately 0.8
h each night). Maximum activity occurred an average of
1 h before low tide. The time between successive peaks of
activity was not significantly different from the duration
of a lunar day (24.8 h), averaging 24.6 + 0.5 h (+SD,
t-test, P= 0.5, n = 20).

The intensity of activity (maximum number of animals
active each night) followed the monthly variation in the
amplitude of the tides (Figure 2). These maximum num-
bers were inversely correlated with the tidal heights at
low tide in both August and May (7? = 0.72, 95% confi-
dence) (Figure 3). The data were divided into new and
full moon tidal series for this analysis because they were
separated by days having neap tides (August 10, May 19).
These dates marked the division between fortnightly ac-
tivity cycles when the moon was in the first and last quar-
ters, respectively, and Onchidella binneyi was inactive.

Repeated attempts were made to find slugs during day-
time ebbing tides, and when their zone was submerged.
Although no surface activity was observed on these occa-
sions, animals were found by turning over rocks adjacent
to the marked study area. These slugs were inactive and
huddled together in small groups. The inactive animals
had their eyestalks and oral lobes retracted, their dorsal
surfaces highly arched, and their mantle papillae extend-
ed, giving them a frilly appearance. Inactive slugs were
never observed copulating (WEBB et al. [1969] reported a
similar finding for Onchidella peronit).

Behavior Independent of Tidal Cues

The daily activity cycles of Onchidella binneyi held in
aquaria were very similar to those of the field population
(Figures 1, 4). When inactive, the slugs huddled together
on the bottoms of the jars, and exhibited the characteristic
frilly appearance. When active, they crawled up the sides
of the jars, above the waterline, and made grazing at-
tempts on the glass with their radulae. Animals were con-
sidered active when observed at least 4 cm above the bot-
tom of their jar.

The details of the activity cycles of the experimental
group were compared to those of the field population.
There was no significant difference between the mean
time at which the first animals became active in the aquar-
ia and in the field (t-test, P= 0.4, n= 18). The mean
time at which the maximum activity occurred was also
not significantly different between the experimental and
field populations (t-test, P = 0.4, n = 18).

DISCUSSION

Onchidella is behaviorally adapted to the intertidal envi-
ronment. When the slugs are submerged in seawater their
lungs are inoperative and they depend upon diffusion of
gases through the mantle surface. The metabolic demands
of locomotion cannot be met during submergence and ac-
tivity is severely limited (FRETTER, 1943; DENNY, 1980).
Feeding excursions and sexual activities are curtailed. In
addition, Onchidella does not have the ability to clamp
tightly to rocks, and is easily dislodged by wave surge
(AREY & CROZIER, 1921; Marcus & Marcus, 1956).
When submerged in seawater, Onchidella must spend its
time buried under rocks. When exposed to the air, pul-

Re Jp bepe ses: MiaPepe i985

NUMBER ACTIVE (aquaria)

Page 379

TIME (hrs)
Figure 4

The mean number of active animals during six nights of activity for the experimental population of Onchidella
binney: held in three 1-L jars filled with seawater (10 animals per jar). Each point is the mean of three replicates
for all six nights of the experiment (n = 18). The bars represent the standard errors of the mean. The arrow
indicates the average time of low tide relative to the activity of the experimental population.

monary respiration supplements pallial diffusion and the
slugs are able to crawl on the top surfaces of rocks where
they feed on diatom films, seek mates, and copulate. How-
ever, their foraging time is limited. Onchidella is shell-less
and subject to dehydration and loss of pulmonary capa-
bilities if not submerged periodically (AREY & CROZIER,
1921; FRETTER, 1943). They will die if exposed to warm,
dry air for prolonged periods. Therefore, Onchidella must
live at a level on the shore that is alternately exposed
and submerged. When the tide ebbs they must emerge,
forage on rock surfaces, and return to cover before the tide
rises and floods their position on the shore.

Onchidella binney: is faced with a choice when its po-
sition on the shore is exposed to the air. The slugs can
maximize their feeding rate and frequency of copulation
by staying on the surfaces of rocks or they can minimize
the risks of dehydration and being dislodged by waves by
returning early to cover. Theoretically, the animals that
would live longest and leave the most offspring would be
those that emerge early and return to cover at the appro-
priate time to balance risks and rewards (SPIGHT, 1982).

To optimize foraging behavior, Onchidella binney: would
have to match its activity to the fortnightly tidal pattern.
The duration of aerial exposure of the slugs’ zone changes
during a tidal cycle. At neap tides, the water level either
does not drop below their zone at all, or drops barely
below it for up to only 4h. At spring tides, the water level
drops well below the slugs’ level on the shore and expo-
sure lasts for 6 to 8 h. As the tides progress from neap to
spring, the O. binney: population becomes more and more

active, seemingly taking advantage of the longer exposure
periods. As the tides progress from spring to neap, the
population becomes less active, seemingly to avoid the risks
of wave action.

The activity rhythm of Onchidella binneyi, with its pe-
riod of a lunar day, is probably a circalunadian rhythm,
as defined by PALMER (1974). The activity patterns of the
O. binney: population are synchronous with the tides and
its nightly activity persists when left in standing seawater
in aquaria. This indicates that either the population is
directly cued by some other environmental factor that fluc-
tuates in relationship with the tides, or that O. binneyi
possesses an internal biological clock.

ACKNOWLEDGMENTS

We wish to thank Dr. R. C. Brusca of the University of
Southern California for critically reading this manuscript.
A sincere note of thanks to Dr. D. A. Thomson of the
University of Arizona and the citizens of Loreto, whose
gracious hospitality and logistic support were a great help
during the field research. Thanks to Mr. and Mrs. F.
Pepe whose contributions supported this work.

LITERATURE CITED

AREY, L. B. & W. J. CROZIER. 1921. On the natural history
of Onchidium. J. Exp. Zool. 32(3):443-502.

Denny, M. 1980. Locomotion: the cost of gastropod crawling.
Science 208:1288-1290.

FRETTER, V. 1943. Studies on the functional morphology and

Page 380

embryology of Onchidella celtica (Forbes & Hanley) and
their bearing on its relationships. J. Mar. Biol. Assoc. U.K.
25:685-720.

Hirasaka, K. 1912. On the structure of the dorsal eye of
Onchidium. Dobutsu Gaku Zasshi (Zool. Mag.) 24:20-35.

IRELAND, C. & D. J. FAULKNER. 1978. The defensive secretion
of the opisthobranch mollusc Onchidella binneyz. Bioorganic
Chem. 7:125-131.

Marcus, E. & E. Marcus. 1956. On Onchidella indolens
(Gould, 1852). Bol. Inst. Oceanogr. S. Paulo 5(1-2):87-94.

PALMER, J. D. 1974. Biological clocks in marine organisms:
the control of physiological and behavioral tidal rhythms.
Wiley & Sons: New York. 173 pp.

The Veliger, Vol. 27, No. 4

RICKETTS, E. F. & J. CALVIN. 1939. Between Pacific tides.
Stanford Univ. Press: Stanford, Calif. 614 pp.
SpiIGHT, T. M. 1982. Risk, reward, and duration of feeding
excursions by a marine snail. Veliger 24(4):302-308.
Watson, H. 1925. The South African species of the molluscan
genus Onchidella. Ann. So. Afr. Mus. 20(4):237-308.
Wess, M., L. G. MOODLEY & A. S. THANDAR. 1969. The
copulatory mechanism in Onchidium peronu. So. Afr. J. Sci.
65(4):107-112.

WELLS, R. A. 1980. Activity pattern as a mechanism of pred-
ator avoidance in two species of acmaeid limpet. J. Exp.
Mar. Biol. Ecol. 48(2):151-168.

The Veliger 27(4):381-385 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

A Mass Mortality of Northern Bay Scallops,

Argopecten trradians trradians,

Following a Severe Spring Rainstorm'

STEPHEN T. TETTELBACH, PETER J. AUSTER,

The University of Connecticut, Marine Sciences Institute, Marine Research Laboratory, Noank, Connecticut 06340

EDWIN W. RHODES, ano JAMES C. WIDMAN

National Marine Fisheries Service, Northeast Fisheries Center, NOAA, Milford, Connecticut 06460

Abstract. Observations of a mass mortality of northern bay scallops, Argopecten irradians irradians,
were made shortly after a severe rainstorm on 5-6 June 1982 during which more than 21 cm of rain
fell on the Poquonock River area in Groton, Connecticut, USA. Mortality levels approached 100% at
locations highest in the estuary, and decreased with distance from the head, and with depth. Observed
levels of bay scallop mortality resulting from estimated periods of exposure to reduced salinities com-
pared well with published laboratory determinations. All other lines of evidence also support the
conclusion that the bay scallop mass mortality resulted directly from low salinities incurred by the

storm.

INTRODUCTION

THE EFFECTS OF salinity reductions on estuarine fauna
depend on the nature of the morphological, physiological,
and behavioral attributes that particular species possess
for coping with changes in salinity (see KINNE, 1964, for
general review). Most bivalve mollusks are especially sus-
ceptible to salinity fluctuations because of their limited
mobility and virtual inability to osmoregulate over wide
ranges of salinity (GILLES, 1975).

As epibenthic estuarine inhabitants, bay scallops may
suffer considerable exposure to freshets in the natural en-
vironment (BROOM, 1976). GUTSELL (1930) reported
mortalities of Argopecten irradians concentricus in North
Carolina that were apparently related to reduced salinities
and suggested that freshets may be extremely destructive
to natural bay scallop populations.

In this paper, we report a mass mortality of northern
bay scallops, Argopecten irradians irradians (Lamarck,

' Contribution No. 168 of The University of Connecticut, Ma-
rine Sciences Institute, Marine Research Laboratory, Noank,
Connecticut 06340.

1819), that occurred in the Poquonock River in Groton,
Connecticut following a severe rainstorm on 5-6 June
1982, during which more than 21 cm of rain was recorded
(City of Groton Water Filtration Plant, unpublished data).

AREA oF STUDY

The Poquonock River is a shallow, well-flushed estuary
adjoining the eastern portion of Long Island Sound (Fig-
ure 1). The mean depth of the river is 0.95 m, the average
tidal range is 0.79 m, and the residual volume of the
estuary at mean low water (MLW) is 945,000 m? (2.5 x
108 gals; Tettelbach, unpublished data). Although detailed
salinity profiles are unavailable, Rafferty (unpublished
data) reports that, during the summer, salinity levels gen-
erally range from 20 to 30%o at the head and 26 to 35%o
toward the mouth of the river.

The major source of freshwater input to the Poquonock
River is Great Brook. The flow of this stream is regulated
by the City of Groton Water Filtration Plant (COGWFP),
which is located about 0.5 km north of the estuary’s head.
Discharge over the weirs of the plant is considered to be
approximately equivalent to the total volume of fresh-

Page 382

The Veliger, Vol. 27, No. 4

ox,

|} —— 41°20’

Sound

Figure 1

Map of the Poquonock River area, Groton, Connecticut, USA,
with insert illustrating its location in New England. Numbers
refer to sampling stations; x, location of the USGS tidal gauge;
+, location of the City of Groton Water Filtration Plant.

water that enters the Poquonock River (Stevens, personal
communication).

An indigenous population of northern bay scallops ex-
ists in the lower half of the estuary. Supplemental plant-
ings of hatchery-reared scallops have been undertaken in
recent years to augment the recreational fishery (STEWART
et al., 1981).

MATERIALS ann METHODS

Initial observations of the effects of the June 1982 rain-
storm involved a qualitative survey of the scallop stocks
and other estuarine fauna by biologist divers along the
west side of the estuary (stations 1, 2) on 8 June 1982
(Figure 1). Water samples were collected and salinities
determined by specific gravity. Tidal stage at the time of
sampling was calculated in relation to values recorded at
a tidal gauge (USGS, 1982, 1983) located about 1 km
from the mouth of the Poquonock River (Figure 1).

On 10 June 1982, the numbers of live bay scallops and
dead scallops with both valves still connected were counted
in situ in 0.25-m? quadrats haphazardly placed in areas
of known scallop concentrations (stations 3, 4). Ambient
temperature and salinity measurements were taken with
a Yellow Springs Instrument Co. Salinity-Conductivity-
Temperature meter. On 11 June 1982, additional 0.25-
m? quadrat counts were made at two depth strata (<1 m,
>1 m) at station 5. Only dead scallops with all or part of
the tissues remaining were counted in addition to live
scallops.

Two mortality estimates were computed based on
quadrat counts of live and dead bay scallops with intact
hinges:

maximum mortality (%)

no. of live scallops

=/1- x 100;
no. of live scallops ;
+ no. of dead scallops
(with or without tissue)
minimum mortality (%)
no. of live scallops
Se ee || 5S OD)

no. of live scallops
+ no. of dead scallops
(with tissue)

Further observations of bay scallop mortality were made
at station 6 on 17 June 1982 when pearl nets (34 x 34 x
28 cm high pyramidal nets constructed of plastic-coated
wire and plastic mesh) containing hatchery-reared juve-
niles were examined. The nets were put in place on 27
May 1982: stocking density was 50 scallops/net (=550/
m?); mean length of the scallops was 4.7 mm. Mesh size
of the nets was 2-3 mm, a size that effectively excluded
all predators.

In order to compare conditions in the estuary and the
status of bay scallop stocks following a less severe storm
than that which occurred on 5-6 June 1982, observations
were made at station 7 one and four days after a storm
on 10 April 1983 during which 7.8 cm of rain was re-
corded (COGWFP, unpublished data). Temperature and
salinity measurements were made in addition to qualita-
tive surveys of the bay scallop population.

RESULTS

Bay scallop mortality estimates and measurements of en-
vironmental parameters made at each station in the Po-
quonock River on the given dates are summarized in Ta-
ble 1.

Initial observations made on 8 June 1982 along the
western side of the Poquonock River (stations 1, 2, Figure
2) revealed that 100% of the bay scallops encountered (40-
50 individuals) were dead. All were gaping widely; tissues
were flaccid and runny, and showed no or only slight
evidence of mechanical damage from scavengers (see Fig-

S. T. Tettelbach et al., 1985

Page 383

Table 1

Summary of bay scallop mortality estimates and parameter measurements acquired at the Poquonock River sampling
stations following the 5-6 June 1982 rainstorm.

Bottom
Station Water depth Bottom salinity temperature

no.* (m) (%o) (°C)

1 1 2.6 —

2 1 3.7 —

6 1 — —

5 0.50-1.0 — —
1.0-1.5 _ —

4 0.75-1.5 14.8 16.5

3 1 13.5 16.5

Time of sampling
(h) (+) after high
tide (—) before

Estimated bay

scallop mortality Sampling date

(%) high tide (1982)
100 2.5 June 8
100 +4.0 June 8
100 — June 17
90.5 (min.) — June 11
67.7 (min.) — June 11
91.3 (max.) 175 June 10
86.2 (min.)
48.0 (max.) =2:25 June 10
0-5 (min.)

* Stations are listed in order of increasing distance from the head of the estuary.

ures 2A, B). Other dead and dying animals in this area
included juvenile winter flounder (Pseudopleuronectes
americanus), cockles (Laevicardium mortoni), and sea cu-
cumbers (Sclerodactyla [=Thyone] briareus), the latter being
greatly bloated. Green crabs, Carcinus maenas, were com-
mon and active; no moribund individuals were observed.

Counts from the 12 0.25-m? quadrats made on 10 June
1982 at station 3 yielded 29 live and 27 dead scallops. All
of the dead individuals seen completely lacked tissue, ex-
cept for three scallops that were observed outside the
quadrats. Based on these counts, the estimate of maximum
bay scallop mortality at station 3 was computed to be 48%,
while the minimum estimate was 0-5%.

The 12 quadrat samples taken at station 4 on 10 June
1982 yielded the following totals: 8 live and 50 dead scal-
lops. Virtually all of the dead individuals still had part or
all of the viscera present inside the shell. The minimum
estimate of mortality at this location was 86.2%, while
maximum mortality was calculated to be 91.3%.

Quadrat counts made at station 5 on 11 June 1982 were
as follows: 0.75-1 m depth—15 live, 124 dead scallops in
20 0.25-m? quadrats; 1-1.5 m depth—231 live, 65 dead
scallops in 20 0.25-m? quadrats. Estimates of minimum
mortality for these two depth strata were calculated to be
90.5% and 67.7% respectively. The composite mortality
estimate for station 5 was 80.4%, which was close to the
estimated minimum mortality for nearby station 4 (86.2%)
where depth strata were not differentiated.

The hatchery-reared juvenile bay scallops that were
being held in pearl nets at station 6 were all found dead
on 17 June 1982.

Observations made on 11 and 14 April 1983 in an area
of bay scallop concentration (station 7) revealed that all
scallops exhibited normal behavior, with velar tentacles
extended, and immediately closed their valves when dis-
turbed. Temperature and salinity measurements taken just
above the sediment surface on 11 and 14 April were 9.0°C,

25.7%0, and 11.0°C, 11%0 respectively. There was no evi-
dence of mortality resulting from reduced salinity.

DISCUSSION

On the basis of the observations described above, it seems
extremely likely that the mass mortality of northern bay
scallops that occurred in the Poquonock River immedi-
ately following the severe rainstorm of 5-6 June 1982
resulted from reduced salinity, as opposed to any other
factor such as predation, disease, siltation, or exposure to
toxic materials. The presence of large numbers of dead
bay scallops with intact tissues, higher survivorship of
scallops in deeper strata, and decreasing scallop mortality
levels at points farther from the head of the estuary all
support the above conclusion. Supplemental evidence also
comes from the fact that the survival rate of scallops plant-
ed in pearl nets at station 6 two weeks after the 5-6 June
rainstorm was 95% for the period July-October (Rhodes
and Widman, unpublished data).

Based on the salinities recorded in the vicinity of sta-
tions 1 and 2 on 8 June 1982 (see Table 1), it appears
that this area of the river may have been subjected to
salinities of 4%o or lower for as much as 48 h (and prob-
ably longer) after the storm ended. It is assumed that
salinities had dropped to near these levels by the time the
storm was over.

If the above assumptions are valid, then the observed
mortalities of bay scallops due to exposure to these re-
duced salinities are consistent with laboratory results ob-
tained by MERCALDO & RHODES (1982). These authors
found that after 6 h exposure to salinities of 0 and 5%o at
temperatures of 13 and 19°C, juvenile northern bay scal-
lops suffered no mortality; but all were dead after 24 h.
When exposed to a salinity of 10% at these temperatures,
scallops suffered 100% mortality after 48 h.

SANDERS ef al. (1965) stated that the magnitude and

Page 384 The Veliger, Vol. 27, No. 4

S. T. Tettelbach et al., 1985

duration of salinity fluctuations are influenced by the size,
volume, and depth of an estuary, by tidal amplitude, and
by the amount (and rate) of freshwater runoff. Although
such factors are important in affecting the extent to which
organisms are stressed by periods of salinity reduction due
to rainstorms and/or riverine discharge, it is also evident
that the timing of a storm event is extremely important.
As is apparent from the results obtained by MERCALDO
& RHODES (1982), survival of bay scallops at low salini-
ties is greater at lower temperatures. Therefore, storm
events leading to reduced salinities may be more harmful
in warmer months of the year when metabolic demands
of estuarine organisms are likely to be greater.

Observations following the rainstorm of 10 April 1983
revealed that although a large amount of precipitation was
recorded (7.8 cm), the volume of freshwater entering the
Poquonock River, 15 million gallons/day (mgd), repre-
sented but 6% of the residual volume of the Poquonock
River at MLW. Resultant salinity reductions were ap-
parently not severe enough to directly cause any bay scal-
lop mortality. In contrast to this, an average of 250 mgd
overflowed the weirs of the COGWFP during the period
6-8 June 1982, representing a daily input equal to the
residual volume of the Poquonock River at MLW. This
inundation of the Poquonock River resulted in the drastic
reduction in salinities and the subsequent mass mortality
of bay scallops.

Under the most extreme conditions, reduced salinities
resulting from storm events may contribute to the local
extinction of certain populations of estuarine inverte-
brates. ANDREWS (1973) reported that many estuarine
species of sponges, tunicates, echinoderms, and mollusks
were eliminated from portions of Chesapeake Bay follow-
ing tropical storm Agnes in June 1972. Although rain-
storms as severe as that of 5-6 June 1982 in the Poquon-
ock River and that of June 1972 in Chesapeake Bay may
occur only once every several hundred years at a specific
locality, such events may be seen as important recurring
processes that can cause mass mortalities of certain inver-
tebrate species.

ACKNOWLEDGMENTS

We would like to extend our appreciation to Drs. Sung
Feng, Lance Stewart, Barbara Welsh, Robert Whitlatch,

Page 385

and Mr. Edgar Miller III for reviewing the manuscript,
and to Mrs. Joyce Lorensen for her editorial and typing
assistance. We thank Mr. Rick Stevens of the City of
Groton Water Filtration Plant for providing access to
rainfall and water supply records; Mr. Brae Rafferty of
Project Oceanology, Groton, Connecticut, for supplying
salinity data; and Dr. Larry Weiss of the United States
Geological Survey, Hartford, Connecticut, for furnishing
tidal gauge data. We are grateful to Mrs. Nikoo Mc-
Goldrick, Mrs. Patricia Staley, and Mr. Robert De-
Goursey for their assistance in preparing the figures. We
also wish to thank The University of Connecticut, Marine
Sciences Institute, Marine Research Laboratory, and the
National Marine Fisheries Service, Northeast Fisheries
Center, Milford Laboratory, for kindly providing the ves-
sels and facilities to conduct this study.

LITERATURE CITED

ANDREWS, J. D. 1973. Effects of tropical storm Agnes on epi-
faunal invertebrates in Virginia estuaries. Chesapeake Sci.
14(4):223-234.

Broom, M. J. 1976. Synopsis of biological data on scallops
Chlamys (Aequipecten) opercularis (Linnaeus), Argopecten ir-
radians (Lamarck), Argopecten gibbus (Linnaeus). FAO Fish.
Synop. 114:44 pp.

GILLES, R. 1975. Mechanisms of ion and osmoregulation. Pp.
259-347. In: O. Kinne (ed.), Marine ecology, Vol. II, Phys-
iological mechanisms, Part I. John Wiley and Sons: Lon-
don.

GUTSELL, J. S. 1930. Natural history of the bay scallop. Bull.
USS. Bur. Fish. 46:569-632.

KINNE, O. 1964. The effects of temperature and salinity on
marine and brackish water animals. II. Salinity and tem-
perature-salinity combinations. Oceanogr. Mar. Biol. Ann.
Rev. 2:281-339.

MERCALDO, R. S. & E. W. RHODES. 1982. Influence of re-
duced salinity on the Atlantic bay scallop Argopecten irra-
dians (Lamarck) at various temperatures. J. Shellfish Res.
2(2):177-181.

SANDERS, H. L., P. C. MANGLESDORF, JR. & G. R. HAMPSON.
1965. Salinity and faunal distribution in the Pocasset Riv-
er, Massachusetts. Limnol. Oceanogr. 10(suppl.):R216-
R229.

STEWART, L. L., P. J. AUSTER & R. Zajac. 1981. Investiga-
tion on the bay scallop, Argopecten irradians in three eastern
Connecticut estuaries June 1980-May 1981. Final report
submitted to Aquaculture Division, Milford Laboratory,
National Marine Fisheries Service, Milford, Conn.

Figure 2

Dead northern bay scallops, Argopecten irradians irradians, photographed four days after the 5-6 June 1982
rainstorm in the Poquonock River. Note the flaccid tissue remains, some of which are being fed on by scavengers:
the grass shrimp Palaemonetes sp. (A) and the mud snail Ilyanassa obsoleta (B). Scavengers initially fed mostly on

scallop viscera, leaving the adductor muscle intact (C).

The Veliger 27(4):386-396 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

Shell Growth, Trauma, and Repair as an

Indicator of Life History for Nautilus

by

JOHN M. ARNOLD

Kewalo Marine Laboratory, Pacific Biomedical Research Center,
University of Hawaii, Honolulu, Hawaii 96813

Abstract.

By examining the shells of Nautilus pompilius, it has been possible to partially reconstruct

the life history of individual animals. Two types of predation were found: (1) boreholes apparently
made by an octopod and most frequently occurring over the left retractor muscle and (2) spalls or
triangular notches apparently caused by Nautilus attacking other Nautilus. This intraspecific predation
(cannibalism) can be divided into: (1) nips—incomplete penetration of the edges of the shell, (2) bites—
removal of beak-sized and shaped pieces of shell, and (3) crunches—removal of large amounts of shell
and mantle. Other types of mechanical damage may remove as much as one-quarter of the shell of the
living chamber and the animal recovers and secretes new shell with an interruption in shell pattern.
Foreign substances in the wound area or damage to the mantle resulted in abnormal shell deposition.
Abnormal growth patterns and lumps were frequently observed. Some of these were caused by com-
mensal organisms but others are of unknown eticlogy. Shell growths were found which appeared to

have been caused by tumors of the mantle.

INTRODUCTION

ATTEMPTS TO STUDY the biology of lesser known animals
are frequently frustrated by the very reason for which they
are not better known: they are either extremely rare or
live in inaccessible places. Although Nautilus has great
intrinsic interests as the last living remnant of a large and
once important marine class (HOUSE & SENIOR, 1981), it
remains poorly known because of its remote habitat. Par-
adoxically, this remote, precise, and stable environment
has allowed Nautilus to retain its primitive nature. Nau-
tilus pompilius is a benthic animal which migrates noctur-
nally from depths as great as 700 m (HAVEN, 1972;
SAUNDERS & WEHMAN, 1977) to depths of about 100 to
150 m where it feeds. Even at 100 m, these animals are
below the workable range of scuba divers. There are two
possible means of study: removal to an artificial environ-
ment and use of indirect evidence to gain insight into the
life history of Nautilus. The latter approach is the subject
of this study.

MATERIALS anD METHODS

This study was carried out on material collected mainly
in October and November 1979 during the last cruise of

the R/V Alpha Helix. Living specimens of Nautilus pom-
pilus were purchased from local fishermen who captured
them in split bamboo traps made for the purpose. These
traps were set usually at depths of approximately 150 m
but each group of fishermen seemed to have favorite depths
and locations in the Tanon Strait between the islands of
Negros and Cebu (123.2°E, 10°N). Although a variety of
different baits was tried, including several varieties of fish,
squid, piglets, and puppies, the consensus of the local fish-
ermen was that freshly killed chicken was most effective.
Between 12 October and 20 November 1979, 332 adult
and juvenile animals were collected and examined and
those showing interesting shell abnormalities or damage
were reserved for further study. Selection was subjective
because of the contingencies of shipboard conditions but
tended to be consistent because specific criteria were used.
All the animals captured were weighed, sexed if possible,
serially numbered, and then held in running seawater
(10-15°C) for variable periods of time; then the shells
were examined in detail. Some animals were maintained
for as long as six weeks in apparent good health.

Shells of living animals that showed repaired damage
or other abnormalities were examined to determine if the
damage was related to capture and subsequent handling

J. M. Arnold, 1985

or if it had occurred naturally. Damage associated with
recent collection was easy to eliminate because of the new-
ness of the fracture or damage to soft tissues.

Fishermen, shell dealers, and children frequently of-
fered empty Nautilus pompilius shells for sale. These shells
were also examined for anomalies. Most of these shells
were “beach” or “drift”? shells which showed evidence of
having been dead for some time before collection. Bored
shells were included for study. Purchased shells were des-
ignated with the prefix ““P” followed by a number.

Included in this study are three abnormal shells re-
cently named Nautilus belauensis Saunders, 1981, from
Palau which were kept in the Waikiki Aquarium for
varying lengths of time. They are designated with the
prefix “W.” The conditions of capture and maintenance
are described by CARLSON (1979). The author retains all
of these shells for further study.

RESULTS

The types of shell abnormalities that reflect the life history
of the individual are categorized as follows: (1) Mechan-
ical alteration of the shell resulting from (a) predatory
damage, and (b) repair of mechanical and/or predatory
damage. (2) Growth alterations caused by (a) imperfect
repair and regrowth, (b) interference by commensal or-
ganisms, (c) abnormal and tumorous growth, (d) artificial
maintenance, and (e) irregular size change.

Mechanical Alterations

Predatory damage: Nautilus shells show two types of
damage related to presumed predation: bored holes and
bites from the shell. Boreholes in or near the terminal
chamber are apparently caused by another mollusk, pos-
sibly an octopod. In 1982 I saw a trap set in the Tanon
Strait that contained six living Nautilus pompilius, one
dead N. pompilius, and a mature male Octopus cyanea.
The dead Nautilus had a borehole in the shell over the
left retractor muscle and a portion of the body had been
eaten. The local fishermen who set the trap said this was
a common occurrence. These boreholes are ovate to dia-
mond-shaped (Figure 1) and show striations on the side
wall. They are subconical in shape and narrowest at the
inner peak end. Shape and size are suggestive of the holes
produced in Strombus and other shells by Octopus vulgaris
(PILSON & Taylor, 1961; ARNOLD & OKERLUND-
ARNOLD, 1969; WODINSKY, 1969; NIXON et al., 1980) and
in Nautilus (TUCKER & MApPEs, 1978). Fifteen such bore-
holes were found in 348 shells (collected and purchased),
with one shell having three holes, two having two holes
each, and all other shells with one hole each. In 10 of 15
instances, the boreholes were located over the left retractor
muscle, and the point of penetration continued through
the conchiolin-like layer separating the muscle from the
shell and to the muscle tissue itself (Figure 1b).

When the borehole was not over the left retractor, the

Page 387

animal was either given to us live, or reportedly was still
alive when taken by the donor. In shell P1, three holes
were bored: two were on the right side of the living cham-
ber 8.0 and 8.8 cm from the lip, and the third hole was
about 7 mm inside the lower edge of the left retractor
muscle. Shell P2 had two completed holes near the mid-
line, one was 6 cm back from the lip and the other was
8.1 cm back and 1.3 cm left of the midline. This animal
was in the early stages of forming a new septum. Shell
P5 was acquired freshly dead with shreds of drying re-
tractor muscle in place. There was one completed hole 9
cm back from the shell lip 1.2 cm to the right of the
midline, and a second hole was over the retractor muscle
scar at least 2 cm from the outermost edge.

The second evidence of predation was obtained by di-
rect observation of captive animals. It was frequently not-
ed that one Nautilus would grip another so the shell ap-
ertures were opposed and the beak of one animal attacked
the lip of the shell of the other animal. Pieces of shell
could be seen and heard to be broken away in these en-
counters, which lasted from minutes to several hours (see
also WARD & WICKSTEN, 1980). Damage varied in se-
verity and was of three types: nips, bites, and crunches.

Nips are here defined as point breaks through the outer
layer of shell (called porcelaneous ostracum by STENZEL
[1964]) to the pearly underlying nacreous layer (Figure
2). When freshly produced (7.e., witnessed), these nips are
usually within 6 mm of the edge of the shell lip and tend
to be oblong and vary in width from 1.2 to 1.5 mm. The
bottom of these nips is usually flat. On some occasions the
nips penetrate through the shell and are subsequently
sealed with a layer of black organic film as described by
STENZEL (1964). The nips do not have the characteristic
diamond shape and striations of boreholes, and frequently
have “shelves” and “plateaus” suggestive of spalls parallel
to the surface of the layers. Occasionally several nips co-
alesce forming a large area of exposed nacre. Occasionally
nips could be seen some distance back from the current
shell edge indicating subsequent growth had occurred.

Bites are defined as triangular beak-shaped pieces re-
moved from the shell at the edge of the aperture. Bites
vary in size depending on how deeply the shell edge was
drawn into the jaws, Frequently, they occur in connected
linear arrays (Figure 3). On occasion, these arrays ex-
tended for several centimeters along the lip of the shell
and when combined make deep curved or scalloped in-
dentations (Figure 4) which may be several square cen-
timeters in area (Figure 6). Frequently, cracks that orig-
inate at the bite coalesce and remove portions of the shell
(see crunches below). Cracks often approximate or par-
allel the direction of the midline, then suddenly curve off
sharply toward one side (Figure 5). This type of break
can be easily duplicated by pressure applied to the shell
surface with a pair of narrow pliers or, less easily made,
by a sharp blow at the lip of a submerged shell. The
curved part of the break almost invariably has evenly
spaced (harmonic?) chipping along its outer surface. In

Page 388

The Veliger, Vol. 27, No. 4

12 of 16 shells of females, this excision occurs on the
animal’s left side.

Crunches are here defined as large areas of missing
shell (7.e., several times larger than the beak area). These
may result either from the coalescence of several bites into
a common break or from the intersection of cracks. Pos-
sibly some of these large “crunches” are the result of me-
chanical damage caused by accidental contact with hard
surfaces or even by attacks by larger unknown animals
(e.g., possibly by turtles, LEHMANN, 1981), but because of
the association of the easily identifiable bites near the
crunches, it appears that at least some are caused by frac-
tures related to the bites (Figure 6). The mechanical dam-
age and large areas of damage resulting from bites or other
unknown factors will be considered together for purposes
of discussion.

Repair of mechanical and/or predatory damage: Al-
most every shell examined in this study showed some evi-
dence of repaired predation or other damage. The degree
of repair and retention of the original shell proportions
varied with the extent of shell and underlying mantle tis-
sue damage. If the mantle was extensively damaged (e.g.,
by attack from another Nautilus), the shell was frequently

imperfectly repaired and subsequent outgrowth was ab-
normal. The effect on the shell varied from interruption
of the striped color pattern to discoloration of the junction
of new and old shell to extensive rough-ribbed irregular
areas covered with layer(s) of black organic material (Fig-
ure 7). The damaged mantle sometimes apparently grad-
ually recovered during regrowth and the distal shell again
became smooth (Figures 5, 8). However, in other cases
the damaged mantle continued to lay down abnormal shell,
and the width of the longitudinal stripes enlarged in pro-
portion to the expansion of the shell diameter (Figure 7).
It was not possible to derive an exact estimate of the per-
centage of shells with repaired breaks because early dam-
age is covered by subsequent whorls and some later dam-
age is repaired, but of the 332 shells examined in the 1979
collection only a few animals (less than 2%) were judged
to be unflawed by breakage at some time in their life span.
Because of shipboard limitations, it was not possible to
determine experimentally how much of the shell could be
removed without causing death of the animal but, judging
from repaired natural breaks (e.g., Figure 9), at least one-
quarter of the shell could be missing and eventually re-
placed. There was no way of estimating the amount of
soft tissue that could be lost, but Figure 10 shows an

Explanation of Figures 1 to 12

Figure 1a, b. a. Position of the borehole over the left retractor
muscle. Note also that this shell had serpulid tubes near the lip
and the barnacle basal plate near the umbilicus (cf. Figure 24).
b. Higher magnification of the borehole shows it to resemble
strongly those found drilled in Strombus shells by Octopus vul-
garis.

Figure 2. “Nips” at the edge of the shell. These are shallow
depressions which occasionally penetrate the shell. Penetrations
become plugged with a layer of black organic material (broad
arrow) (shell 363).

Figure 3a, b. a. “Bites” witnessed being taken by aquarium
specimens in the shell of Nautilus. b. Bites on the edge of the
shell of a collected specimen. These bites are the size and shape
of the adult beak. There is also a repaired “crunch” on the left
of the midline (arrow) (shell 441).

Figure 4. Damage from repeated bites on the shell. This animal
has obviously been attacked frequently and the mantle was dam-
aged at the midline so that it secreted abnormal ribbed shell.
The mantle damage on the left side eventually was overcome
and normal shell was again produced (shell 489).

Figure 5. Break and loss of shell probably due to joined cracks
resulting either from a bite or from mechanical damage to the
shell. The curved portion of the break has harmonic chipping
!l along the edge. Note the abnormal shell outgrowth (arrow)
which resulted from mantle damage. This suggests the break
may have originated from cracks due to bites.

Figure 6. Crunches are caused either by environmental damage
or by coalescence of several bites into a common large break.
There is a tendency for these crunches to be on the left side of

the females which is where the beak of the male would make
easiest contact during copulation. The arrows indicate abnormal
shell outgrowth probably caused by mantle damage that even-
tually regenerated (shell 576).

Figure 7. Abnormal outgrowth after damage to the mantle. Black
organic material is laid down upon normal shell and the shell is
deeply ridged. This black material may be subsequently lost
resulting in longitudinal striations of the shell (shell 449).

Figure 8. Abnormal outgrowth and repair of the shell as well
as recovery of the mantle tissue (narrow arrow). At the broad
arrow a large area of shell was cracked and elevated. The mantle
then laid down an internal patch that was connected to the old
outer shell by black organic material and small spheres of shell.
Subsequent repair to damage along the black line resulted in a
single layer of shell being formed. Note the bites evident at the
black line and the recovery of mantle damage (pointer) near the
lip (shell P11).

Figure 9a,,b. An extensive area of shell was replaced and the
stripe pattern was not resumed in the new shell (shell 182).

Figure 10. About one-quarter of the hood has been bitten off on
this specimen and extensive damage to the shell was evident
(arrows). Several severed arms and the buccal mass are evident
and are apparently in active regeneration (shell 357).

Figure 11a, b. Patched area of shell penetration. In “a” the circle
approximates the area of the internal patch. In “b” the patch
can be seen to be composed of several layers of shell (shell 332).

Figure 12. Section of the patched region of shell 332. A space
exists between the old damaged shell and the newly laid patch.
Black organic material covers the inside of the patch.

Page 389

J. M. Arnold, 1985

STUDY NATURE NOT BOOKS" tac

Page 390

The Veliger, Vol. 27, No. 4

animal in which extensive damage to the cirri, hood, buc-
cal mass, and shell has occurred (probably due to attack
by another Nautilus) and regeneration was occurring.

Growth Alterations

Imperfect repair and regrowth: Completeness of dam-
age repair was proportional to the severity of damage.
Where the shell was not completely penetrated by a nip,
there was usually no repair, or at most a thin layer of
non-reflective white material was laid down inside the
shell. Where the shell had been penetrated, a pearly ma-
terial was laid down upon the organic black material.
Figures 11a and b show the outside and inside of a shell
apparently partially penetrated by a sharp object (perhaps
the lower jaw of the beak). The shell at the exact point
of impact was partially crushed and fragments remained
in the area. The mantle laid down several concentric lay-
ers of shell inside the point of penetration, building up a
total thickness of 2.56 mm as compared with a thickness
of 1.05 mm in the unaffected area (Figure 12). In shell
312 (Figure 13), there were two points of penetration that
forced pieces of shell inward. These crushed pieces were
subsequently covered by a layer of black organic material
and an irregular pearly layer was built up on it that
completely closed both openings (Figure 13b). In its thick-
est area, the pearly material was 2.12 mm thick, not in-
cluding the organic layer. No new shell was cemented
directly upon the damaged shell, rather it was laid down
upon the black organic material.

In some cases where the shell was penetrated, foreign

material accumulated between the shell and the mantle
tissue that apparently altered shell deposition. In shell 438
(Figure 14) the outside of the shell was penetrated and a
tunnel continued internal to the damaged area. When the
animal had been freshly removed from the shell, the hole
had a characteristic rank odor. This odor has been noticed
in other animals with abnormal shells. There was no trace
of any burrowing organism visible with a dissecting mi-
croscope before or after the shell was sectioned. The dam-
age was apparently repaired before the proximal hole was
formed, as the removed distal shell had been replaced to
a thickness of approximately 1 mm. The inside of the
proximal hole had an ovate opening 1.16 cm long which
was surrounded by a thickened area about 4.6 mm in
maximal thickness and covering approximately 37 cm’.
The inside and outside openings were connected by an
irregularly angled opening. In section the thickened area
can be seen to be made of several layers of laminar shell
laid down upon sheets of black organic material and in-
terspersed with granular, gray, amorphous, loose material
(Figure 14c).

In three other instances, abnormal growths were ob-
served in shells in the 1979 Alpha Helix collection. In shell
P15 (Figure 15) an abnormality of unknown origin caused
growth to cease at the midline. Eventually growth was
retarded along the leading edge and a line of black organic
material accumulated. The source of the outside line ap-
parently was correlated with an internal abnormality
within the shell itself that ended at the beginning of the
external deformation. A line of irregular black organic
material was found within the nacreous layer and porce-

Explanation of Figures 13 to 19

Figure 13a, b. Repair of a double penetration. There is a layer
of black organic material between the old shell and the newly
deposited pearly layer.

Figure 14a, b, c. Traumatic shell growth caused by an open hole
into the space between the mantle and shell. There are several
layers of black organic material alternating with irregular small
spheres of shell and organic debris. The inner surface of the
repaired shell is non-reflective and porous, and gray in color. No
prismatic or columnar shell is evident and a pearly layer is
absent (shell 438).

Figure 15a, b. Cessation of growth by internal shell abnormality.
The arrow indicates the approximate beginning of an internal
linear area of black organic material similar in appearance to
the external black line. Growth ceased for a time when the
abnormal shell reached the outer shell surface and a line of black
material was laid down at the then distorted edge of the shell
(shell P15).

Figure 16a, b. A large serpulid worm (broad arrow) in the
umbilical region has inhibited outgrowth of the hood and a layer
of pearly shell about 1 mm thick has been laid down (pointer).
The original margin of the black organic material in the umbil-
ical region has been retracted about 0.5 cm (arrows).

Figure 17a, b. Inhibition of growth by two serpulid worms in
shell 337. In this case two small serpulid worms developed in
the umbilical region (arrows indicate the ends of the worm tube).
Apparently when the Nautilus tissues encountered the worm tubes,
growth was inhibited until the worm tubes were completely cov-
ered with black organic material and some shell because a strong
black line delimits the former lip and the pattern of striping is
interrupted (a). This shell was sectioned (b) and it was apparent
that the uniform increase in chamber size was interrupted (lc =
length of the chamber in cm at the outside midline) and during
this time the shell increased in thickness (wt = wall thickness at
the outside midline in mm). Normal chamber size increased again
and the shell regained its normal thickness; apparently then the
obstructing worm tubes had been covered. For purposes of pre-
sentation the chambers are numbered in reverse order of ap-
pearance.

Figure 18. Barnacle basal plates in the umbilical region. A sec-
ondary limit of the black organic layer was developed about 3.3
mm back from the original margin (broad arrow).

Figure 19. Shell 332 with putative growth inhibition caused by
coralline algae in the umbilical region (arrows).

J. M. Arnold, 1985 Page 391

METRIC

METRIC

2345 67 8 9]
2.2 2.4 2.1 1.81.9 1.7 1.6 1.6
1.9 0.9 0.9 0.8 0.8

Page 392

The Veliger, Vol. 275 Nos 4

laneous ostracum. This line began as a few black specks
1.7 cm proximal to the former shell lip, and it expanded
laterally and vertically producing an elongate irregular
space filled with unoriented layers of black organic ma-
terial. At maximum it was 3.05 mm wide but less than
0.5 mm thick. No identifiable remnant of any substance
of animal origin was found. The shell resumed growth
after a period of inhibition and the color pattern was re-
established. At the inner margin of the umbilicus a space
2.5 x 2.0 mm caused by centrifugal displacement of the
distal-most chambers curved backward at least several mm
(Figure 15b). Growth in volume of the chambers from
the first chamber to the seventh was uniform, decreased
sharply (probably due to hatching, COCHRAN et al., 1981),
then resumed increasing uniformly again until the thir-
teenth chamber which measures 6.7 mm at the outer mid-
line as compared with 7.8 mm for the twelfth chamber
and 8.0 mm for the fourteenth chamber. From the four-
teenth chamber outward, the chambers increase uniform-

ly.

Interference by commensal organisms: Many speci-
mens of Nautilus pompilius had commensal organisms
growing on them. Ectoprocts commonly were found in a
midline patch extending from a few centimeters beyond
the edge of the dorsal mantle fold to the point at which
the stripe pattern ends. The ectoprocts apparently did not
damage the shells. Depending on position and size, ser-
pulid worms and at least two species of coralline algae did
interfere with growth (Figures 21, 22, 23, 24). Large ser-
pulid worms in the umbilical area seemed to cause the

most shell response (shell 338, Figure 16). At first the
tube was oriented radially toward the umbilicus; then,
perhaps on contact with the hood, it deviated and followed
the contour of the hood. At the posterior edge of the hood,
a layer of pearly shell approximately 1 mm thick and 1
cm wide was laid down upon the black organic film. Total
growth was apparently retarded because the original lead-
ing edge of the black material was retracted about 0.5 cm
on the umbilical region opposite the worm tube. Shell 337
shows stronger growth inhibition evidently caused by ser-
pulid worms (Figure 17). Two worm tubes were laid
down in each umbilical region when the shell was several
chambers smaller than when captured. They were even-
tually covered with black organic material and reduced to
a low ridge. The worm tubes, however, (1) inhibited
growth and a black line developed at the edge of the im-
mature lip, (2) interrupted uniform chamber growth, and
(3) changed the thickness of the shell (Figure 17b). Ap-
parently when the worm tubes were encountered, cham-
ber growth suddenly decreased and the outer shell wall
increased in thickness from less than 1 mm to 1.9 mm for
the next chamber, then decreased to 1.5 mm thick in the
following chamber, then resumed a thickness of 1 mm
again in the next chamber. The position of the black line
coincides exactly with the position of the lip at the time
of worm tube interference (Figure 17a).

Growth was seemingly inhibited by barnacles at the
edge of the right umbilical region of shell P3 (Figure 18).
There is a secondary layer of black film 3.3 mm back
from the edge of the maximum extent of the underlying
black film. On shell 332 a pink coralline alga has encrust-

Explanation of Figures 20 to 26

Figure 20a, b, c, d. Effects of a massive shell inclusion of un-
known etiology upon subsequent growth of the whole animal. a.
Shows there was a sharp break in the uniform volume increase
(arrow) of the shell. The shell was thickened on this side. b.
Shell sectioned to show the inclusion zn situ (shell slightly tipped
to facilitate visibility). The proximal portion is covered with a
layer of shiny shell. c. Higher magnification of the inclusion.
Three areas are evident: the hard shiny proximal area (1) is
separated from a layered gray area (2) by an area of mixed black
organic material and irregular spheres (3). d. Section through
the inclusion showing a layer of prismatic shell (ps) proximally
covering an area primarily filled with layers of black organic
material upon which spherical gray shell has been laid down
(bmss) followed by thin stacks of layers of whitish shell (shell
506).

Figure 21. Solid pearly inclusion in shell 303. When this lump
was sectioned, it was found to be pure pearl, and no obvious
irritant or growth inducing substance was evident.

79

Figure 22a, b, c. Shell W8 (Nautilus belauensis) has an open
umbilicus on the right side of the shell (Figure 22c) and on the
left side the umbilicus is closed (Figure 22b). Inside the left

umbilicus there is a large inclusion which may possibly have
interfered with shell secretion in this area (Figure 22a).

Figure 23a, b, c. Shell W9 (Nautilus belauensis) was kept in the
Waikiki Aquarium for about 14 months during which time the
shell grew abnormally outward from the lip. Note the secondary
line of black organic material across the umbilicus (a, b) and the
alternation of the layers of black organic material and shell (ar-
rows).

Figure 24. The edge of shell W6 (Nautilus belauensis) had extra
pearl laid down upon the inside of the lip. The dotted line in-
dicated the approximate limit of the new pearly layer. The arrow
indicated alternation of black organic material and white shell.

Figure 25. Shell 300 shows an abrupt decrease in the size of the
living chamber for unknown reasons. It appears the relatively
slight damage at the midline and right side occurred after the
shell diameter had begun to decrease. There is a line of black
organic material at the margin where the decrease began. This
was an immature female.

Figure 26. Comparison of two juveniles taken from the same
locality in the Tanon Strait. The right shell has an open um-
bilicus.

Page 393

J. M. Arnold, 1985

Page 394

The Veliger, Vol. 27, No. 4

ed the umbilical area (Figure 19) and the nearby shell
aperture. This animal appeared to be mature judging from
a line of black organic material at the lip overlain by thin
pearl. The posterior margin of the hood had retracted
about 4.5 mm from the edge to a new layer of pearl about
i mm thick laid upon the black film. A small empty worm
tube 1.22 cm behind the leading edge of the lower aper-
ture apparently did not inhibit growth.

Abnormal and tumorous growths: In shell 506 (Figure
20) an abnormal growth of unknown cause inside the shell
affected subsequent growth of the animal. The outer third
of the living chamber is decreased in size (arrow) and a
dark line runs from the left umbilical region to 2.2 cm to
the right of the midline. The right side of the living cham-
ber decreases in diameter by several millimeters and the
shell is thickened in the incurving region. A few bites
taken near the midline and edge appear to have occurred
after the chamber volume decrease. The abnormal growth
extends from a thick region 12 cm back of the shell lip to
about 5 cm from the lip. Distally it is covered with a thin
but regular layer of pearly shell enclosing a lump 0.918
cm thick at its maximum. This layer grades into prismatic
blocks that eventually grade into a thin gray layer upon
a multilayered area that eventually fuses to the shell of
the chamber (Figure 20d). Inside this abnormal growth
the distal thickened portion is composed of thin sheets of
shiny black organic material alternating with spaces
crowded with spherical lusterless gray droplets. These
droplets average less than 0.5 mm in diameter and tend
to occur in stacks, or where exposed to the surface they
form loose discontinuous sheets. Toward the mantle, the
layers of gray droplets intergrade into prisms of white
shell material packed together in rhombohedric columns.
The prisms frequently have horizontal sheets of black or-
ganic material intersecting them. Approximately the distal
2 cm of this abnormal growth is arranged into sheets of
calcareous material laid down upon the layers of black
organic material which are spaced an average 0.2 mm
apart. These sheets open outward so the areas between
them communicate with the mantle space. The whole ab-
normal growth lies upon a layer of shell secreted upon the
original shell (Figure 20d). There are two distinct ridges
of hard thickened shell covered with clear chonchiolin
which run from the edges of the growth to the columella
and underlie the retractor muscles. No external wound
appears associated with this internal growth which arises
proximally without any evident source and tapers distally
to normal appearing shell. Laterally it joins the surround-
ing shell with areas of brownish-black discoloration. There
was no striking gross difference in the mantle when this
animal was removed from its shell. In shell 303 (Figure
21), a solid lump 7.5 x 4.5 x 3.5 mm projected toward
the body from the inner side of the whorl opposite the
attachment of the retractor muscle. When this lump was
sectioned, it was found to be pure pearly shell with a

homogeneous structure. There was no indication of any
irritant or substance that would have induced this growth.

Artificial maintenance: Shells of three animals recently
described as Nautilus belauensis (SAUNDERS, 1981) were
kept in the Waikiki Aquarium for various lengths of time
and all showed abnormal growth. The right side of shell
W8 has an open umbilicus that extends at least 2.7 cm
inward (Figure 22). It is not filled with the hard callus
typically found in N. pompilius from the Tanon Strait.
The left umbilicus is covered with a layer of shell leaving
a shallow depression. Immediately inside the aperture near
the left umbilicus, there is an incrustation composed of
black organic material, pearly shell, and dense discolored
shell that projects about 7.2 mm into the living chamber.
It is about 1.76 cm wide and about 1.6 cm in length. It
has an irregular conical shape with an outwardly directed
opening. The black organic layer on the inner whorl was
asymmetrical on this animal.

Shell W9 (Figure 23) was kept.in captivity for about
fourteen months (CARLSON, 1979), during which time
growth was asymmetrical and the shell was atypically
thickened with a heavy pearly layer averaging 2.6 cm
wide. In places the new shell was slightly thicker than 4.1
mm but averaged 3.5 mm thick for most of its extent. This
pearl appeared to be laid down upon a thickened edge of
several layers of black organic material. On the right side,
the shell lip is recurved upon itself and has an irregular
contour. The umbilical region has a secondary thickened
layer (about 1.5 mm) of black organic material laid down
on the original thin layer but back from the margin about
1.2 cm. A third specimen of Nautilus belawensis (W6) kept
in the Waikiki Aquarium has a completely open umbili-
cus and also shows a layer of shiny pearl that has seem-
ingly thickened the lip for a width of about 2.35 cm. This
shell also has several irregular layers of black organic
material interspersed between the shell layers at the ex-
treme edge (Figure 24).

Irregular size changes: Occasionally there are shells that
seemingly exhibit uniform shell growth until, for un-
known reasons, the diameter of the outer chamber abrupt-
ly decreases in diameter (Figure 25). Sometimes these
growth decreases seem to correlate with obvious shell
trauma (breakage or internal growths) (Figure 16), but
often the cause is not obvious. In two cases juvenile N.
pompilius caught in the Tanon Strait did not have the
umbilical region covered by shell and thereby superficially
resembled Nautilus macromphalus (Figure 26). There was
no detectable growth inside the shell similar to that in
shell W8 reported above.

DISCUSSION

From the above results, it is evident that a partial history
of the life of an individual Nautilus is laid down as the
shell is secreted, repaired, or added to during the life span.

J. M. Arnold, 1985

With reasonable care, it is possible to interpret this record
and thereby indirectly gain insight into the environmental
and, to some extent, physiological stresses encountered by
Nautilus. The following life history events are discussed:
(1) evidence of predation by known predators, (2) repair
of shell damage, (3) imperfect growth and/or regrowth,
(4) influence of commensal organisms, (5) anomalies of
shell deposition (tumors), (6) environmental inadequacies
of artificial maintenance, and (7) size changes due to un-
known causes.

Predation: Two of the many possible types of predators
have been tentatively identified: Octopus and Nautilus. The
boreholes found in Nautilus shells resemble the holes
bored by Octopus in other molluscan shells (PILSON &
TAYLOR, 1961; ARNOLD & OKERLUND-ARNOLD, 1969;
WoDINSKY, 1969; NIXON, 1979a, b, 1980). The size, shape,
and texture are similar. The rasp marks, however, may
be a product more of the type of shell being drilled than
a characteristic of the predator (NIXON, 1980). It is hard
to imagine any animal other than Octopus being respon-
sible because of the requirement of swimming by the pred-
ator and the ability of the predator to learn to position the
borehole exactly over the retractor muscle (cf, ARNOLD &
OKERLUND-ARNOLD, 1969). Furthermore, the presence of
an Octopus cyanea in the same trap as a bored and par-
tially eaten Nautilus is strong circumstantial evidence that
Octopus is a predator upon Nautilus. In drilling Strombus
shells, Octopus vulgaris consistently drills in a particular
location (ARNOLD & OKERLUND-ARNOLD, 1969;
WoODINSKY, 1969). In Nautilus, holes bored in places other
than over the retractor muscle were apparently unsuc-
cessful. Living Nautilus specimens were captured with
complete boreholes not over the muscle but shells that
contained living animals were never found with completed
boreholes over the muscle area. The tendency to drill on
the animal’s left side may possibly be due to the right-
hand position of the beak of the male which would make
an attacker to the right side more vulnerable to counter-
attack. Therefore, there would be an advantage to learn
to bore consistently over the left retractor muscle.

That Nautilus is preyed upon by other Nautilus was
directly established. Almost all shells show evidence of
beak-shaped bites and attacks of this type were witnessed.
Frequently during copulation the male bites the shell,
mantle, hood, and arms of the female in his grasp. Because
of the off-center position of the spadex, the male’s beak
opposes the left side of the female’s midline, and there is
a tendency (12 of 16 cases) for the females to have more
repaired crunches on the left side. The question remains
whether the encounters are lethal; in the case of the ani-
mal shown in Figure 10, extensive damage was done yet
regeneration was occurring. If not lethal, attacks must be
detrimental because repair and regeneration require met-
abolic effort.

Repair of shell damage: The most striking damage in-

Page 395

volved the breaking away of large areas of shell (Figures
5, 6, 9). It is not possible to identify the causes of all the
large breaks but certainly some must be the result of con-
joined cracks from bites. Displaced edges are frequently
rejoined by a layer of black organic material which later
becomes covered by shell (Figure 8). In other cases a line
of new shell secretion starts proximal (posterior) to the
fissure giving the impression that the mantle retracted and
then began to move outward again as it secreted replace-
ment shell. Thus, extensive areas of original shell lined
with new shell are common. At the junction of the “new”
and “old” shell, there may or may not be a layer of black
organic material underlying the new shell.

Imperfect growth and/or regrowth: The success of re-
growth of shell (replacement as opposed to repair of dam-
aged but still present shell) seems dependent on the extent
and severity of the original damage. If the mantle was
damaged, subsequent secretion of new shell frequently
was abnormal (Figures 7, 8, 10). Apparently the interjec-
tion of foreign substances into the wound area resulted in
abnormal regrowth (Figure 14). In most instances the
mantle responded to shell trauma by first covering the
damaged area with black organic material which was, in
turn, covered with shell. In these cases the shell appar-
ently was of uniform density and structure unlike the
abnormal (tumorous) shell seen in Figures 14 and 20.

Influence of commensal organisms: Apparently, any-
thing that physically inhibits advance of the body will
interrupt the advance of the body whorl. Objects such as
worm tubes, barnacles, or even such flat encrustations as
coralline algae will interrupt growth. LANDMAN (1983)
also observed that barnacles would inhibit Nautilus shell
growth. This interruption of growth results in thickening
of the shell and the interruption of uniform volume in-
creases of the chambers (Figure 17). The thickening of
the shell wall suggests that despite interruptions of out-
growth of the living tissue, secretion of the shell continues
at a uniform rate. Further growth apparently is dependent
upon the ability of the mantle and soft tissues to overcome
or cover the interfering foreign objects with hard tissue.
In most instances a layer of black organic material is laid
over the foreign object. Apparently, when chamber out-
growth is inhibited by a foreign object in the umbilical
area, the mantle retracts slightly and begins to secrete
pearl over the black layer. Once the obstruction is over-
grown or in some way removed, growth resumes, leaving
a record as a decrease in chamber size, thickening of the
shell, a layer of black material, or a combination of these
demarcations.

Anomalies of shell deposition (tumors): Examination of
the growths deposited in the shell shown in Figure 20 and
similar shells shows that the three normally coordinated
steps of shell secretion can become disassociated. Instead
of a uniform laying down of shell components upon and

Page 396

The Veliger, Vol. 27, No. 4

among the organic matrix, the black organic material is
laid down in macroscopic sheets interspersed with either
prismatic masses of shell or aggregates of granular ma-
terial. Obviously, this reflects the pathological state of the
secreting mantle and fits the definition of tumorous
growths. Unfortunately, the mantles that secreted these
growths are not available for histological examination.

Environmental inadequacies of artificial maintenance:
Figures 23 and 24 illustrate two shells of animals that
were held in captivity and abnormal growth occurred at
the shell lip of these presumably mature animals. MARTIN
et al. (1978) have figured similar abnormal growth in a
specimen of Nautilus macromphalus kept in captivity. Be-
cause the animals shown in Figures 19 and 20 were kept
at typical environmental temperatures, it can be assumed
that temperature is not the sole factor in this abnormal
growth. Possibly either the conditions of maintenance were
inadequate (in the same way in New Caledonia and Ha-
wall, which seems unlikely) or (more likely) irritation to
the shell lip and mantle caused by continued contact with
the walls of the container caused abnormal growth.

Size changes due to unknown causes: The cause(s) of
the decrease in diameter of the terminal chamber in some
shells is an open question without the soft parts. Whether
this was from the need to regenerate lost tissue, as would
be the case of the animal of Figure 10, or from disease or
other metabolic upset requires further study.

CONCLUSIONS

It seems possible to infer by indirect methods that Nautilus
living in their natural deep sea environments are: (1) sub-
jected to predation by a hole-boring animal, probably an
octopod, and certainly by other Nautilus; (2) damaged by
massive mechanical shell breakage which they are able to
repair and compensate for; (3) inhibited in their growth
by the presence of external commensal organisms and pos-
sibly unfavorable or physiological conditions; and (4) sub-
ject to abnormal shell growth caused either by environ-
mental conditions or tumorlike pathologies of unknown
etiology. These changes in shell morphology should also
be an event in the fossil record.

ACKNOWLEDGMENTS

I would like to thank Dr. Dale Bonar for reading and
improving this manuscript, Ms. Lois D. Williams-Arnold
for her help in the early phases of this work, Mrs. Frances
Okimoto for preparing the manuscript, Miss Andrea No-
vicki for her photographic expertise, and Mr. Wilson Via-
loces for providing the animals used in the study. The

staff of the Waikiki Aquarium, particularly Mr. Bruce
Carlson, provided the artificially maintained animals. The
Republic of the Philippines graciously allowed the R/V
Alpha Helix to carry out its mission in their national waters,
and the National Science Foundation of the United States
provided financial support (Grant #PCM 77-16269). Fi-
nally, I would like to thank the crew of the Alpha Helix
and my many scientific colleagues who made this work
possible, and the staff at Scripps Institute of Oceanogra-
phy who supported this cruise.

LITERATURE CITED

ARNOLD, J. M. & K. E. OKERLUND-ARNOLD. 1969. Some
aspects of hole-boring predation by Octopus vulgaris. Amer.
Zool. 9:991-996.

CaRLSON, B. 1979. Chambered Nautilus: a new challenge for
aquarists. Freshwater Mar. Aquar. 2:48-51.

CocuRaN, J. K.,D.M. Rye & N. H. LANDMAN. 1981. Growth
rate and habitat of Nautilus pompilius inferred from radio-
active and stable isotope studies. Paleobiology 7:469-480.

HAVEN, N. 1972. The ecology and behavior of Nautilus pom-
pilius in the Philippines. Veliger 15:75-80.

House, M. R. & J. R. SENIOR. 1981. The Ammonoidea: the
evolution, classification, mode of life and geological useful-
ness of a major fossil group. Academic Press: London.

LANDMAN, N. H. 1983. Barnacle attachment on live Nautilus:
implications for Nautilus growth rate. Veliger 26:124-127.

LEHMANN, U. 1981. The ammonites. Cambridge University
Press: London.

MartINn, A. W., I. CATALA-STUCKI & P. D. WarbD. 1978. The
growth rate and reproductive behavior of Nautilus macrom-
phalus. N. Jb. Geol. Palaont. Abh. 156:207-225.

Nixon, M. 1979a. Hole-boring in shells by Octopus vulgaris
Cuvier in the Mediterranean. Malacologia 18:431-443.
Nixon, M. 1979b. Has Octopus vulgaris a second radula? J.

Zool. (Lond.) 187:291-296.

Nixon, M. 1980. The salivary papilla of Octopus as an acces-
sory radula for drilling shells. J. Zool. (Lond.) 190:53-57.

Nixon, M., E. MACCONNOCHIE, & P. G. T. HOWELL. 1980.
The effects on shells of drilling by Octopus. J. Zool. (Lond.)
191:75-88.

Pitson, M. E. Q. & P. B. TayLor. 1961. Hole drilling by
Octopus. Science 134:1399-1400.

SAUNDERS, W. B. 1981. A new species of Nautilus from Palau.
Veliger 24:1-7.

SAUNDERS, W. B. & D. A. WEHMAN. 1977. Shell strength of
Nautilus as a depth limiting factor. Paleobiology 3:83-89.

STENZEL, H. B. 1964. Living Nautilus. Pp. K59-K93. In: C.
Teichert (ed.), Treatise on invertebrate paleontology, Part
K, Mollusca 3. Geol. Soc. Amer. and Univ. Kansas Press.

Tucker, J. R. & R. H. Mapes. 1978. Possible predation on
Nautilus pompilius. Veliger 21:95-98.

Ward, P. & M. K. WICKSTEN. 1980. Food sources and feeding
behavior of Nautilus macromphalus. Veliger 23:119-123.
WopInsky, J. 1969. Penetration of the shell and feeding on

gastropods by Octopus. Amer. Zool. 9:997-1010.

The Veliger 27(4):397-405 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

Records and Morphology of Lomanotus stauberi
Clark & Goetzfried, 1976, from the Panamic Pacific

TERRENCE M. GOSLINER

Department of Invertebrate Zoology, California Academy of Sciences,
Golden Gate Park, San Francisco, California 94118

HANS BERTSCH!

Biological Sciences, National University, San Diego, California 92106

Abstract. Specimens of Lomanotus stauberi Clark & Goetzfried, 1976, were collected from the Gulf
of California and Pacific coast of Baja California. Morphologically they closely resemble the type
material and other specimens collected from the Atlantic coast of Florida. The material collected in this
study constitutes the first record of the genus Lomanotus from the Pacific Ocean.

INTRODUCTION

Lomanotus stauberi was described from the Atlantic coast
of Florida (CLARK & GOETZFRIED, 1976). Since then no
additional records of the species have been published.
Specimens from the Gulf of California and the Pacific
coast of Baja California (Figure 1) represent a significant
extension of known range of L. stauberi and the first record
of the genus from the Pacific Ocean. In this paper we
describe the morphology of these specimens and compare
them with type material and other specimens collected
from the Atlantic coast of Florida.

DESCRIPTION

Material: Paratypes—National Museum of Natural His-
tory, Washington, D.C., USNM 710760, 6 specimens,
Sebastian Inlet, Florida (27°51'33”N, 80°26'45”W), 1 m
depth, 26 July 1975, Kerry Clark.

California Academy of Sciences, San Francisco, CASIZ
050217, 3 specimens, Boca Raton Inlet, Florida, 1 m depth,
1 June 1975, Terrence M. Gosliner.

California Academy of Sciences, San Francisco, CASIZ
050218, 3 specimens, 10 km S of Loreto, opposite road to

' Mailing address: 4444 W. Pt. Loma Blvd. #83, San Diego,

California 92107.

El Rincon, Gulf of California, Baja California Sur, Mex-
ico (26°55'N, 111°20’W), 3 m depth, 14 January 1984,
Terrence M. Gosliner.

California Academy of Sciences, San Francisco, CASIZ
050219, 5 specimens, S end of Isla Magdalena, 200 m
inside Punta Entrada, Magdalena Bay, Baja California
Sur, Mexico (24°34’N, 112°03’W), 3-4 m depth, 16 Jan-
uary 1984, Hans Bertsch.

External morphology: The living animals (Figure 2)
range in length from 11 to 14 mm. The ground color is
translucent white. The notum, head, and sides of the body
are brown. Irregular darker brown lines extend the entire
length of the notum. A network of opaque white lines
covers much of the oral tentacles, rhinophores, branchial
lobes, and notum. An opaque white spot is present at the
apex of each branchial lobe.

The oral veil is semicircular in shape (Figure 4). The
anterior limit of the head is often upturned when the
animals are actively crawling. The anterior foot corners
are short and angular. Extending from the dorsolateral
portion of the head are a pair of simple, acutely pointed
oral tentacles. The rhinophore sheaths possess 5-9 shal-
low lobes. The perfoliate rhinophores are composed of 9-
12 lamellae. The notum is expanded into 22-25 branchial
lobes per side. Each lobe terminates at a short digitiform

Page 398

PA
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Ay i
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. AL
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ona
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Figure 1

Map of Baja California, indicating collecting localities.

process. The genital aperture is situated ventral to the
fourth and fifth branchial lobes, while the anus is located
ventral to the tenth to twelfth branchial lobes.

Internal morphology: The jaws (Figure 5) possess an
elongate masticatory margin that bears several rows of
platelets, each of which bears 7-10 denticles (Figure 6).
The radular formula is 20 x 7-14.0.7-14 in the single
specimen examined in this study (Figures 7-11). There
are 6-15 denticles on the outer side and 6-10 denticles on

The Veliger, Vol. 27, No. 4

the inner side of the radular teeth. The teeth are widest
near the rachis of the radula and become progressively
narrower near the outer margins.

The reproductive system (Figure 13) contains a narrow
preampullary duct, which expands into a wider, saccate
ampulla. The ampulla narrows into the postampullary
duct and divides into the oviduct and vas deferens. The
oviduct expands into a bilobed receptaculum seminis and
narrows again where it joins the albumen, membrane and
mucous glands of the female gland mass. The female glands
terminate at the female aperture. The vas deferens is pros-
tatic throughout its length and terminates at a muscular,
conical penis, which is unarmed.

Egg mass: The white egg mass (Figure 3) consists of a
convoluted ribbon (about 14 mm long and 2 mm across
the coils) which is oriented along the longitudinal axis of
the hydroid stem. Within the mass there is a single egg
per capsule.

Natural history: Specimens were found on colonies of the
stinging plumularid hydroid Lytocarpus philippinus (Kir-
chenpauer, 1872) in 1-4 m of water. The animals and
egg masses are remarkably cryptic on the hydroid colonies.
At both localities where Lomanotus stauberi was collected
in this study, Lytocarpus forms dense aggregations on the
tops and sides of boulders where there is slight surge.

DISCUSSION

Material collected from the Gulf of California and the
Pacific coast of Mexico was compared with the original
description of Lomanotus staubert Clark & Goetzfried,
1976. Paratype specimens and specimens collected by one
of us (TMG) from the Atlantic coast of Florida were also
compared with the present material. In virtually all as-
pects, the morphology of the present material agrees with
that known from the Atlantic coast of Florida and there
is no doubt that they are conspecific.

The radula of the Pacific material contains more teeth
per half row (up to 14) than that described by CLARK &
GOETZFRIED (1976) where there are 7-9 teeth per half
row. However, the paratype specimen examined in this
study (Figure 12) contained up to 11 teeth per half row.
Clark & Goetzfried also noted that specimens from Flor-
ida had as many as 31 branchial lobes per side, whereas
in the present material there is a maximum of 25 per side.
This is likely a function of the somewhat smaller body
size of the Mexican material. These slight differences are
considered minor and within the normal range of varia-
tion.

CLARK & GOETZFRIED (1976) mentioned that the penis
of Lomanotus stauberi is conical and unarmed, but the
remainder of the reproductive morphology was not de-
scribed. The configuration of the reproductive organs de-
scribed here is based upon the examination of three spec-
imens, two from Isla Magdalena and one paratype from
Sebastian Inlet, Florida. No morphological variability was

T. M. Gosliner & H. Bertsch, 1985 Page 399

Explanation of Figures 2 and 3

Figure 2. Lomanotus stauberi Clark & Goetzfried, 1976. Living Figure 3. Lomanotus stauber: Clark & Goetzfried, 1976. Egg
animal. mass.
detected. The reproductive morphology of two other species O t

of Lomanotus has been described. In L. stauberi the recep-
taculum seminis is bilobed while in L. phiops Marcus,
1957, it is undivided and in L. gene: Verany, 1844, it is
absent (see Marcus, 1957; SCHMEKEL, 1970). m

Figure 4

Lomanotus stauberi Clark & Goetzfried, 1976. Ventral view of
head: f, foot; fc, foot corner; m, mouth; ot, oral tentacle. Scale =
3.0 mm. |

Page 400 The Veliger, Vol. 27, No. 4

63.4%
S8GUM

15KV WO: 11MM = =6$: 66000 P:60671

Explanation of Figures 5 and 6

Figure 5. Lomanotus stauberi Clark & Goetzfried, 1976. Jaw. Figure 6. Lomanotus stauber: Clark & Goetzfried, 1976. Masti-
catory elements.

T. M. Gosliner & H. Bertsch, 1985 Page 401

15KY WO: 11MM

Explanation of Figures 7 and 8

Figure 7. Lomanotus stauberi Clark & Goetzfried, 1976. Entire Figure 8. Lomanotus stauber: Clark & Goetzfried, 1976. Teeth
radula of specimen from Loreto. 1-3.

Page 402 The Veliger, Vol. 27, No. 4

15KY WO: 11MM

Explanation of Figures 9 and 10

Figure 9. Lomanotus stauberi Clark & Goetzfried, 1976. Teeth Figure 10. Lomanotus stauberi Clark & Goetzfried, 1976. Teeth
4-7. 7-12.

T. M. Gosliner & H. Bertsch, 1985 Page 403

15KV WO:i1MM 8 $:@6606 P:a9069

Explanation of Figures 11 and 12

Figure 11. Lomanotus stauberi Clark & Goetzfried, 1976. Teeth Figure 12. Lomanotus stauberi Clark & Goetzfried, 1976. Half
10-14. row of radular teeth of paratype specimen.

Page 404

The Veliger, Vol. 27, No. 4

Figure 13

Lomanotus stauberi Clark & Goetzfried, 1976. Reproductive system: alb, albumen gland; am, ampulla; mu, mucous
gland; pe, penis; pr, prostate; rs I, receptaculum seminis I; rs II, receptaculum seminis II; 2a, female aperture; éa,

male aperture. Scale = 1.0 mm.

It is difficult to make definitive judgments regarding the
systematics of Lomanotus, as the majority of species are
incompletely described. CLARK & GOETZFRIED (1976)
provided a detailed review of the known morphological
features of members of the genus. From their data it is
clear that L. staubert is most similar to L. phiops Marcus,
1957, and L. vermiformis Eliot, 1908. Clark & Goetzfried
noted important radular differences between L. stauberi
and L. phiops. Lomanotus phiops also differs from L. stau-
beri by its undulate rather than straight notal border and
by its undivided rather than bilobed receptaculum sem-
inis. It is difficult to compare L. stauberi with L. vermifor-
mis. ELIOT (1908) described only the external morphology

and radula of L. vermiformis and provided no figures of
his specimens. The apparent similarity of the two taxa
warrants further morphological study, particularly as the
prey hydroid of L. staubert, Lytocarpus philippinus is cir-
cumtropical in its distribution (NUTTING, 1900) and is
known from the Red Sea.

Lomanotus stauberi is certainly more widespread than
originally indicated and has a broad distribution within
the Panamic Province, having been found in the Gulf of
California and on the Pacific coast of Baja California. The
fact that it has not previously been encountered in the
region can be attributed directly to its specialized habitat
and extremely cryptic appearance when on its prey.

T. M. Gosliner & H. Bertsch, 1985

Page 405

ACKNOWLEDGMENTS

We thank the other members of the joint California Acad-
emy of Sciences—Centro de Investigacién Cientifica y Ed-
ucacion Superior de Ensenada Expedition to Baja Cali-
fornia Sur—Luis Aguilar, David Catania, Michael
Ghiselin, Hans Hermann, Welton Lee, and Robert Van
Syoc—for their assistance and support in the field. Bar-
bara Weitbrecht prepared the line drawings and Judy
Steiner printed the final photographs; to them we extend
our appreciation. We also thank Dr. Joseph Rosewater
of the National Museum of Natural History for allowing
us to examine type material. This research was supported
solely by the George E. Lindsay Field Research Fund of
the California Academy of Sciences.

LITERATURE CITED

CLARK, K. & A. GOETZFRIED. 1976. Lomanotus stauberi, a new
dendronotacean nudibranch from central Florida (Mollus-
ca: Opisthobranchia). Bull. Mar. Sci. 26(4):474-478.

EuioT, C. 1908. Notes on a collection of nudibranchs from the
Red Sea. J. Linn. Soc. Lond. (Zool.) 31:86-122.

Marcus, E. 1957. On Opisthobranchia from Brazil. J. Linn.
Soc. Lond. (Zool.) 43(292):390-486.

NutTTIinG, C. 1900. American hydroids. Part 1. The Plumu-
laridae. Smithsonian Institution Special Bulletin 1-285.
SCHMEKEL, L. 1970. Anatomie der Genitalorgane von Nudi-
branchiern (Gastropoda Euthyneura). Pubbl. Staz. Zool.

Napoli 38:120-217.

THE VELIGER

© CMS, Inc., 1985
The Veliger 27(4):406-410 (April 1, 1985)

Rediscovery and Redescription of Rostanga lutescens
(Bergh, 1905), comb. nov. (Gastropoda: Nudibranchia)
by
SCOTT JOHNSON'

Mid-Pacific Research Laboratory, Enewetak, Marshall Islands, Box 1768, APO San Francisco 96555

AND

HANS BERTSCH?

Biological Sciences, National University, San Diego, California 92106

Abstract. Living specimens of Rostanga lutescens (Bergh, 1905) are described for the first time. The
generic position, left uncertain by Bergh, is emended, and the reproductive system and the proper
arrangement of the radular teeth are described. This species is now known from Timor, Indonesia, and

Enewetak Atoll.

AMONG THE opisthobranch collections of the Siboga Ex-
pedition was a single, preserved, 14 mm long dorid nu-
dibranch, which BERGH (1905) questionably assigned to
the genus Discodoris Bergh, 1877. Recent collections at
Enewetak Atoll, Marshall Islands, west central Pacific
(11°33'N, 162°20’E) have yielded three specimens essen-
tially fitting Bergh’s description; the species is here de-
scribed for the first time in the living state. Voucher spec-
imens, with mounted radulae and color slides of the living
animal, have been deposited in the Bernice P. Bishop Mu-
seum (number 207564), Honolulu, Hawaii, and the United
States National Museum, Washington, D.C.

The spelling of the species name needs comment. In
BERGH’S text (1905:107) describing the new species is
printed: “Discodoris ? lutesceus Bgh. n.sp.” There is no
further mention of the name in the text. However, in the
two indices (Inhaltsverzeichnis, p. 244; Register, p. 247),
and on the explanation to plate XIV, the species is listed
as lutescens. The single misspelling is obviously a printer’s
error, which Bergh himself corrected (BERGH, 1905:248,
Corrigenda): “Seite 107 statt: Disc. lutesceus, lese man:

»”

lutescens.

' Mailing address: P.O. Box 25702, Honolulu, Hawaii 96825.
* Mailing address: 4444 W. Pt. Loma Blvd. #83, San Diego,
California 92107.

Rostanga Bergh, 1879
Rostanga lutescens (Bergh, 1905), comb. nov.

Reference and synonymy: Discodoris lutescens BERGH,
1905:107-108; pl XIV, figs. 22-28.

Material examined: One specimen, 12 x 4 mm. Lagoon-
side Medren Island, Enewetak Atoll, Marshall Islands;
under dead coral, 5 m; 2 August 1981, leg. S. Johnson.

One specimen, 19 x 8 mm. Lagoonside Enewetak Is-
land, Enewetak Atoll, Marshall Islands; under dead coral
at night, 5 m; 26 February 1982, leg. L. Boucher.

One specimen, 15 x 6 mm. Lagoonside Enewetak Is-
land, Enewetak Atoll, Marshall Islands; under dead coral,
5 m; 14 July 1982, leg. S. Johnson. This specimen, illus-
trated in Figure 1, has been deposited in the Malacology
Department of the Bishop Museum under number 207564.

Habitat: All three specimens were collected on shallow,
subtidal, lagoon reefs consisting of sand, rubble, and lime-
stone flats in 3-6 m of water. At one time, these reefs
were apparently populated by numerous colonies of the
tabletop coral Acropora hyacinthus (Dana, 1846). Most of
these colonies are long dead and lying on the bottom, with
their undersides thickly overgrown with sponges, bryo-
zoans, tunicates, and other encrusting organisms.

Description: The notum is soft and elongate-oval, and its

S. Johnson & H. Bertsch, 1985

Page 407

at
- sgt

Figure 1

Photograph of living Rostanga lutescens, 15 X 6 mm.

wide margin hides the foot. The dorsal surface is densely
crowded with fine, rounded papillae from which protrude
bundles of spicules (caryophyllidia), giving the animal a
hispid appearance. Notal color is light cream-yellow to
light tan, usually with close-set, large, round, very slightly
darker brownish spots. Irregularly scattered over the dor-
sal surface are small patches of opaque white. Mid-dor-
sally the notum appears more pinkish to orange in color,
apparently because of the coloration of the underlying
viscera. The underside of the overhanging hyponotum is
translucent white with a white network of epidermal spic-
ules. The foot is translucent white to pale orange, with
light-orange, relatively long and slender oral tentacles. The

! 100

rhinophores, which protrude from spicule-edged pockets,
have transparent stalks and yellow-brown clubs, each
bearing 12-16 oblique, darker colored lamellae. Bran-
chiae are colored as the rhinophores and consist of about
6 small, tripinnate stalks crowded together in a close circle
around the anus. In ethanol, the animals become white
with grayish viscera.

The radulae of the 19 and 15 mm long specimens mea-
sured 2.1 x 1.3 mm and 1.5 x 1.0 mm respectively, and
the radular formulae were 56 (70.0.70) and 51 (56.0.56).
The morphology of the teeth differed slightly between the
two individuals. Selected teeth from a typical right half-
row of the larger specimen are shown in Figure 2, and a

aN eel

Figure 2

Rostanga lutescens, 19 mm long specimen: selected radular teeth from the right half-row. Scale bar in um.

Page 408

The Veliger, Vol. 27, No. 4

22

wr

37 45

f 100 |

Figure 3

Rostanga lutescens, 15 mm long specimen; selected radular teeth
from the right half-row. Scale bar in um.

few of the more variant teeth from the smaller specimen
in Figure 3. Generally, innermost laterals are hamate with
1 to 5 small inner denticles and 1 or 2 large outer denti-
cles. Outwardly, teeth become larger, and denticulation
may disappear by the middle of the half-row. Outer teeth
are very elongate, with the tip split into as many as 5 very
long, sometimes bent, fingerlike terminal spines. The out-
ermost teeth become slightly shorter again. The long outer
teeth overlap much of the radula when mounted on a slide,
making details difficult to resolve. Buccal armature con-
sists of long, slightly curved elements, which are rather
bluntly pointed rods bearing ringlike, transverse thicken-
ings (Figure 4).

The reproductive system (Figure 5) is similar to that
reported for other species of Rostanga (compare with

50

Figure 4

Rostanga lutescens; buccal element. Scale bar in um.

SCHMEKEL & PORTMANN, 1982:text fig. 7.9 c, and plate
31, fig. 2; and Marcus, 1958:fig. 36). A long, narrow
vagina terminates in a spherical bursa copulatrix, from
which an equally narrow uterine duct leads into the nida-
mental gland complex slightly below the ampullary and
prostatic ducts. An ovate receptaculum seminis is at the
end of a rather long, narrow duct budding from approx-
imately the middle of the uterine duct. A long, curved
ampulla leads into an ampullary duct that joins with the
prostatic duct external to the nidamental glands. The wide,
white, somewhat granular appearing prostate curls over
180° and leads into a much narrower, short penis.

Discussion: BERGH’S original description (1905) mentions
that there were numerous black dots along the margin of
the animal. The dark spots of our animal are at times
apparently composed of small darker colorations. These
do not seem to be contradictory descriptions. Moreover,

Table 1

Radular characteristics and body coloration of species of Rostanga (modified in part from THOMPSON, 1975:490).

Terminal denticles of

Species Body color Hamate lateral teeth marginal teeth Distribution
R. rubra (Risso, 1818) red first: 4 or 5 small lateral denticles bifid east Atlantic
following: 1 large side denticle
R. temerana Pruvot-Fol, 1953 — — bifid east Atlantic
R. evansi Eliot, 1906 violet-gray = multifid east Atlantic
R. byga Marcus, 1958 red — multifid west Atlantic
R. arbutus (Angas, 1864) red first: 13 or 14 denticles multifid west Pacific
R. muscula (Abraham, 1877) red first: 20-30 denticles multifid west Pacific
(2-4 terminal)
R. atrata (Kelaart, 1859) black — multifid Indo-Pacific
(10-15 terminal)
R. lutescens (Bergh, 1905) cream yellow, first: 1—5 inner denticles multifid west Pacific
light tan 1 or 2 outer (up to 5)
following: 1 side denticle
R. pulchra MacFarland, 1905 red first: 4-11 denticles multifid east Pacific

S. Johnson & H. Bertsch, 1985

Page 409

Pro

Figure 5

Rostanga lutescens; anterior genital mass. A, ampulla; B, bursa copulatrix; N, nidamental gland complex; Pe, penis;
Pro, prostate; R, receptaculum seminis; U, uterine duct; V, vagina.

our specimens match his animal in general shape, size,
spiculose surface, and small gills. The radular teeth of the
Enewetak specimens also resemble those in Bergh’s de-
scription, reproduced here in Figure 6, except for their
arrangement. According to BERGH (1905), the elongate,
denticulate teeth were in the middle of the half-row, and
the outermost were smooth and hamate, like those from
the middle of the half-row of one of the present specimens.
Bergh, however, did note that he was uncertain as to how
the radula was constructed: “Es gliickte nicht den Bau der
Raspel genauer zu bestimmen” (BERGH, 1905:108). Rad-
ulae with elongate, narrow teeth are easily jumbled, and
details can be difficult to resolve. Considering Bergh’s un-
certainty regarding the arrangement of the elongate, den-
ticulate teeth, it seems most likely that the correct place-
ment of the teeth from the Siboga specimen should be as
we describe from the conspecific Enewetak specimens.

Bergh was uncertain of the generic placement of his
specimen, stating that he was unable to verify the arrange-
ment of the gills (according to BERGH, 1891:129-130, tri-
or quadripinnate gills are important to differentiate species
of Discodoris). Although difficult to determine even in the
living specimens from Enewetak, close examination found
them to be tripinnate. However, the gill arrangement is
not a differentiating characteristic, at the generic level, for
this species.

Most characteristic and diagnostic for the generic place-
ment of this species is the shape of the radular teeth.
THOMPSON (1975:487) concisely describes the Rostanga
radula: ‘“‘radula broad, without median tooth, lateral teeth
numerous and hook-shaped, marginal teeth bifid or mul-
tifid and brush-like.” Comparison of our illustrations
(Figures 2, 3) and BERGH’s (1905:pl. XIV, figs. 23-28;
reprinted here as Figure 6) with those of other species of

Page 410

Mn 22
27 CS 28.
i
26

Reproduction of illustration of radular teeth by BERGH, 1905:
pl. XIV, figs. 22-28.

Figure 6

Rostanga (e.g., MACFARLAND, 1966:pl. 35, figs. 1-8;
THOMPSON, 1975:fig. 4; SCHMEKEL & PORTMANN, 1982:
pl. 20, fig. 14; BaBa, 1949:fig. 74) indubitably confirms
our identification of this species as a Rostanga. Other fea-
tures, such as reproductive system morphology and struc-
ture of the buccal elements, also match those of Rostanga.
Rostanga lutescens is separable from the eight other species
of Rostanga by its external coloration and radular char-
acteristics (Table 1).

Rostanga hartley: Burn, 1958, has simple hamate teeth;
the innermost teeth have no accessory lateral denticle and
the thin, outermost 5 or 6 marginal teeth do not have their
tips split into a bifid or multifid arrangement (BURN, 1962:
164, fig. 15). The species probably should not be included
in the genus Rostanga.

Externally, Rostanga lutescens bears considerable re-
semblance to Jorunna alisonae Marcus, 1976, and Disco-
doris fragilis (Alder & Hancock, 1864), both found in the
same general area at Enewetak. Jorunna alisonae differs
externally in its grayish color with darker grayish, vari-
ably sized circular spots, and internally in radular and
reproductive system morphology (see the figures of /. al-
isonae in Kay & YOUNG, 1969:185, as /. tomentosa; and
in Marcus, 1976:40). Discodoris fragilis is much larger
than R. lutescens, with more grayish coloration and more
variation in the size of the dorsal, darker colored blotches
(see the photographs in BERTSCH & JOHNSON, 1981:40).

The Veliger, Vol. 27, No. 4

Discodoris fragilis also lacks caryophyllidia, having simple
tubercles. Again, radular tooth morphology easily sepa-
rates the two species (see the figures in Kay & YOUNG,
1969:187; and in EDMUNDs, 1971:340).

This is apparently the first record of Rostanga lutescens
since its original description from Timor, Indonesia
(BERGH, 1905). The present collection from Enewetak
(over 4500 km northeast of its type locality) indicates that
the species is probably more widely distributed, at least
in the western and west central Pacific.

ACKNOWLEDGMENTS

Many thanks to Lisa Boucher for diving assistance, in-
cluding the collection of one of the specimens of Rostanga
lutescens. Portions of this work were performed at the
Mid-Pacific Research Laboratory, Enewetak, Marshall
Islands.

LITERATURE CITED

Basa, K. 1949. Opisthobranchia of Sagami Bay, collected by
His Majesty the Emperor of Japan. Iwanami Shoten, To-
kyo. 4+ 2+ 194 + 7 pp.

BERGH, L. S. R. 1891. Die cryptobranchiaten Doriden. Zool.
Jahrb. Abt. Syst. 6(1):103-144.

BEeRGH, L. S. R. 1905. Die Opisthobranchiata der Siboga-
Expedition. Monographie 50:1-248.

BERTSCH, H. & S. JOHNSON. 1981. Hawaiian nudibranchs.
Oriental Publ. Co.: Honolulu. 112 pp.

Burn, R. 1962. Notes on a collection of Nudibranchia (Gas-
tropoda: Dorididae and Dendrodorididae) from South Aus-
tralia with remarks on the species of Basedow and Hedley,
1905. Mem. Nat. Mus. Vict. 25:149-171.

Epmunps, M. 1971. Opisthobranchiate Mollusca from Tan-
zania (Suborder: Doridacea). Zool. J. Linn. Soc. Lond. 50(4):
339-396.

Kay, E. A. & D. K. Younc. 1969. The Doridacea (Opistho-
branchia: Mollusca) of the Hawaiian Islands. Pacific Sci.
23(2):172-231.

MacFarLanD, F.M. 1966. Studies of opisthobranchiate mol-
lusks of the Pacific coast of North America. Mem. Calif.
Acad. Sci. 6:xvi + 546 pp.

Marcus, Er. 1958. On western Atlantic opisthobranchiate
gastropods. Amer. Mus. Novitates 1906:1-82.

Marcus, Ev. Du B.-R. 1976. On Kentrodoris and Jorunna
(Gastropoda Opisthobranchia). Bolm. Zool., Univ. Sao Pao-
lo 1:11-68.

SCHMEKEL, L. & A. PORTMANN. 1982. Opisthobranchia des
Mittelmeeres. Nudibranchia und Sacoglossa. Springer-Ver-
lag: Berlin. 410 pp.

Tuompson, T. E. 1975. Dorid nudibranchs from eastern Aus-
tralia (Gastropoda, Opisthobranchia). J. Zool. (Lond.)
176(4):477-517.

The Veliger 27(4):411-417 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

Patelloida chamorrorum spec. nov.: A New

Member of the Tethyan Patelloida profunda

Group (Gastropoda: Acmaeidae)

DAVID R. LINDBERG

Museum of Paleontology, University of California, Berkeley, California 94720

GEERAT J. VERMETJ

Department of Zoology, University of Maryland, College Park, Maryland 20742

Abstract.

Patelloida chamorrorum spec. nov. from the Mariana Islands in the tropical western

Pacific is described. The new species is a member of an ancient patellacean group that first appeared
in the Eocene of the Paris Basin, and is today represented by scattered endemic populations throughout
the tropics. This group, typified by Patellorda profunda Deshayes, is diagnosed for the first time and its
distribution in space and time documented; members of the group are closely associated with calcareous
substrates. Patelloida deshayesia nom. nov. is proposed as a replacement name for the homonym Patella

glabra Deshayes.

INTRODUCTION

ONE OF THE MOST common gastropods of the rocky inter-
tidal zone in Guam and other islands in the southern
Marianas is an undescribed patellacean limpet of the ge-
nus Patelloida. Its recognition is significant not only be-
cause it contributes to a better understanding of the fauna
of the Mariana Islands, but also because the new species
is a member of an ancient lineage whose living members
are scattered as endemic populations throughout the trop-
ics. In this paper we describe the new species and outline
its relationship to other living and fossil members of the
Patelloida profunda group, a Tethyan clade that appears
to be specialized for life on calcareous substrata.
Abbreviations are as follows: AHF—Allan Hancock
Foundation (on permanent loan to LACM); ANSP—
Malacology Department, Academy of Natural Sciences,
Philadelphia, PA; CASIZ—Department of Invertebrate
Zoology, California Academy of Sciences, San Francisco,
CA; LACM—Maalacology Section, Natural History Mu-
seum of Los Angeles County, Los Angeles, CA; UCMP—
Museum of Paleontology, University of California,

Berkeley, CA; USNM—Division of Mollusks, U.S. Na-
tional Museum of Natural History, Washington, D.C.

SYSTEMATICS
ACMAEIDAE Forbes, 1850
PATELLOIDINAE Oliver, 1926

Shell: Shell composed of four layers. Outer surface of
shell and interior margin complex prismatic. Next inner
layer concentric crossed-lamellar, followed by myostra-
cum, and radial crossed-lamellar layers.

Radula: Lateral teeth three pairs, uni- or multicuspid;
marginal teeth two pairs or lacking. Ventral plates com-
plex or simple.

Animal: Eyes present. Gut looping complex or highly
simplified. Pericardial sac penetrated by rectum in some
species. Excretory organs paired or with single right ex-
cretory organ and brood chamber. Gill typically present
in nuchal cavity, but may be replaced by secondary gill
in mantle groove, or absent.

Page 412

Patelloida Quoy & Gaimard, 1834

Patelloida Quoy & GAIMARD, 1834:349, type-species by
subsequent designation of Gray, 1847:158, Patelloida ru-
gosa Quoy & Gaimard, 1834.

Shell: Typically stout, with thick intermediate area
composed of concentric crossed-lamellar layer. Sculpture
variable but radial component usually present and con-
centric growth line sculpture typically threadlike and pro-
nounced in complex prismatic layer.

Radula: Lateral teeth variable in size and shape; mar-
ginal teeth two pairs, cusps complex. Ventral plates com-
plex; sutures, anterior processes and/or lateral extensions
present in most taxa.

Animal: Gut looping complex; two excretory organs,
one on either side of rectum; gill present in nuchal cavity.
Oral lappets present in some species. Mantle edge often
thickened with large tentacle/gland complexes.

Cretaceous to Recent. Past and present tropical and
warm-temperate seas.

The Patelloida profunda Group

CHRISTIAENS (1975:93) first recognized the ‘“‘Patelloida
profunda Group,” and referred several species to it, based
on their resemblance (Table 1). The group is character-
ized for the first time as follows:

Light-colored shells of moderate to high profile. All
slopes typically straight with rounded radial ribs; brown
radial markings common. Ventral plates of radula com-
plex with strong lateral processes and sutures; lateral teeth
typically of equal size and shape. Recent species closely
associated with calcareous substrates in tropical nearshore
environments.

Patelloida chamorrorum
Lindberg & Vermeij, spec. nov.

(Figures 1-4, 10-12)

Patelloida flammea Quoy & Gaimard: HEDLEY, 1915:713
[non Quoy & Gaimard, 1834].

Patelloida sp.: VERMEI, 1971:316; VERMEIJ et al., 1984 [in
press].

Acmaea conoidalis auctt. [non Pease, 1868].

Shell (Figure 1): Shell of medium profile, apex slightly
anterior of center. All slopes straight to weakly convex.
Sculpture of approximately 35 primary ribs, smaller sec-
ondary ribs intercalated between most primary ribs. Ra-
dial sculpture overlain by rugose, concentric growth lines
creating pustules on some primary ribs. Exterior of shell
dirty white with 13 dark radial rays. Rays red-brown and
intermittent on eroded portions of the shell. Interior mar-
gin white with dark markings corresponding to exterior
rays. Intermediate area translucent white, with vague ex-
terior rays. Central area strongly outlined by opaque white
callus, tinted with orange-yellow.

Radula (Figures 2, 3): First pair of lateral teeth set

The Veliger, Vol. 27, No. 4

Table 1

Recent members of the Patelloida profunda group.

Taxon Distribution

Patelloida profunda

Patelloida profunda albonotata
Patelloida profunda ivani
Patelloida profunda mauritiana
Patelloida profunda omanensis
Patelloida calamus

Western Indian Ocean

South Africa

Northwestern Australia

Mauritius

Gulf of Oman

Temperate Southern
Australia

Southern Marianas

French Polynesia

Caribbean

Panamic

Java and New Guinea

Palau Group

Patelloida chamorrorum*
Patelloida conoidalis
Patelloida pustulata*
Patelloida semirubida*
Patelloida sp.*

Patelloida sp.*

* Newly assigned species.

close together on anterior edge of basal plates; cusps blunt.
Second pair of lateral teeth directly posterior to first pair;
cusps rounded. Third pair of lateral teeth lateral to second
pair; cusps rounded. Lateral tooth edge elongated forming
lateral extension that terminates near edge of ventral plates.
Marginal teeth two pairs, cusps spoonlike; shafts elongate,
terminating near middle of next posterior tooth row. First
lateral plates tear-drop shaped, affixed to rounded ante-
rior extension of the basal plate. Second lateral plates
posterior to first plates; posterior edges straight, separated
from third lateral plates by partial suture. Third lateral
plates rounded. Ventral plates highly complex with an-
terior processes, lateral extensions, and strong anterior,
posterior and lateral sutures. Posterior medial portion of
plates marked with semicircular suture. Anterior edges of
ventral plates concave, posterior edge convex.

Animal: Pigmentation lacking. Oral lappets present on
snout, well-developed laterally and posteriorly; however,
anterior portion of lappets weak (Figure 4). Mantle edge
thickened with numerous large tentacle-gland complexes.
These structures correspond to the fine crenulations around
the perimeter of the aperture. Looping of the gut complex,
intestine passing over digestive gland several times; eight
sections of the intestine and stomach visible in some spec-
imens (=4 loops).

Holotype dimensions: Length 14.1 mm, width 11.2 mm,
height 5.9 mm.

Type locality: Mariana Islands: Guam; Asanite Bay
(13°20'N, 144°46’E), leg. G. J. Vermeij, 10 July 1970.

Type material: Holotype UCMP 37522; 6 paratypes
UCMP 37523. Paratypes have also been deposited in the
collections of the USNM and LACM.

Distribution: Western Pacific: Mariana Islands; Cocos Is-
land (AHF Acc. 1022)(13°14'N, 144°39’E), Guam [Type
locality], Saipan (LACM 101634) (15°11’N, 145°45’E),
and Tinian Island (LACM 101633)(14°58'N, 145°38’E).

D. R. Lindberg & G. J. Vermeij, 1985

Material examined: 18 lots, more than 100 specimens.

Etymology: The specific name, chamorrorum, is in hon-
or of the Chamorro, the people of the Marianas.

Discussion: Other patellacean limpets in the Marianas
that could be confused with Patelloida chamorrorum in-
clude small encrusted specimens of Patella flexuosa Quoy
& Gaimard, 1834, and Cellana radiata orientalis (Pilsbry,
1891). Patella flexuosa has a lower profile and more ir-
regular margin than P. chamorrorum. The central area
of P. flexuosa is colored with orange-yellow; in P. cha-
morrorum the central area is only tinted. Radulae of the
two species are quite different. Patella flexuosa has three
pairs of marginal teeth, six pairs of lateral teeth, and a
central tooth (3-6-1-6-3); P. chamorrorum has two pairs
of marginal teeth, three pairs of lateral teeth, and lacks a
central tooth (2-3-0-3-2). Patella flexuosa has a secondary
gill; P. chamorrorum lacks a secondary gill.

Cellana radiata orientalis, which co-occurs with Patella
flexuosa on wave-dashed algal ridges, differs from Patel-
loida chamorrorum in several important ways. The Cel-
lana species has an irregular shell surface overlain by nu-
merous, coarse riblets, and because of the uneven shell
surface, the shell margin is also irregular. In C. radiata
orientalis the shell structure is nacre-like (foliated) rather
than porcelaneous as in P. chamorrorum. The radular
tooth formula of C. radiata orientalis is 3-2-0-2-3 and lacks
a nuchal cavity gill but does have a secondary gill.

In their original description of Patelloida flammea, QUOY
& GAIMARD (1834:354) reported this species from both
Hobart-Town, Tasmania, and from Guam. HEDLEY
(1915) proposed that P. flammea should be restricted to a
species from Guam, and that the Tasmanian species was
actually Patella mixta Reeve, 1855. However, IREDALE
(1924) and OLIVER (1926) have pointed out that Quoy &
Gaimard selected the Tasmanian species as the typical
form of P. flammea (see PONDER & CREESE [1980] for a
recent discussion of the identity of P. flammea). We agree
that the species described and illustrated by Quoy & Gai-
mard as P. flammea is not from Guam, and more specif-
ically, is not the species described herein as P. chamor-
rorum. Quoy & GAIMARD (1834) illustrated the snout of
P. flammea (pl. 71, fig. 24). This drawing clearly shows
weakly developed oral lappets (Figure 5); the oral lappets
of P. chamorrorum are strongly developed (Figure 4),
and the difference between these two states is too extreme
to be a preservational artifact.

Specimens of the new species Patelloida chamorrorum
have been confused with members of the Patelloida pro-
funda (Deshayes, 1863) group. CHRISTIAENS (1975:93) re-
ferred P. profunda and the subspecies P. p. albonotata
(Smith, 1901), P. p. mauritiana (Pilsbry, 1891), P. p. oma-
nensis Christiaens, 1975, P. p. ivani Christiaens, 1975,
plus P. conoidalis (Pease, 1868) and P. calamus (Crosse &
Fischer, 1864), to this group stating that they had “a
certain resemblance and probably the same ancestor.”” We

Page 413

concur with Christiaens and refer P. chamorrorum to this
group. Patelloida chamorrorum is distinguished from oth-
er members of the group by shell characters, external
anatomy, and radular characters.

Patelloida chamorrorum has been often labeled in mu-
seum collections as P. conoidalis (Figure 6). Rib number
and strength clearly define these two species. In P. conoi-
dalis there are more ribs (50-60+) and the primary ribs
are therefore narrower. The shell of P. conoidalis also has
a stronger concentric sculpture that sometimes produces a
cancellate pattern and the shell lacks coloration (no dark
rays or red markings). Both species can have orange-yel-
low intermediate areas and the thickened central area can
also be tinted. In the field the two species can be quickly
distinguished by the shape of the oral lappets on the snout
(cf. Figures 4, 7).

Patelloida chamorrorum differs from the nominal
species of the group, P. profunda, by having fewer riblets,
a more central apex, and by lacking the brown central
area and white and light brown rays on the exterior shell
surface. Patelloida chamorrorum differs from P. calamus
(Figure 8) and P. p. mauritiana (Figure 9) in similar ways.
Both P. calamus and P. p. mauritiana have more ribs (70-
80+) than P. chamorrorum (30-40). In P. calamus the
primary and secondary ribs are not well differentiated;
both P. chamorrorum and P. p. mauritiana have distinct
primary and secondary ribs. Patellorda p. mauritiana dif-

_fers from P. chamorrorum by (1) having heavier, thread-

like concentric growth lines that produce pustules at some
intersections with the radial ribs, and (2) being dingy
white in color and lacking radial rays and red markings.
Patelloida calamus has fewer (6-8) dark rays than P. cha-
morrorum. In P. calamus the central area is sometimes
red-pink; in P. p. mauritiana the intermediate area is often
yellow-orange and thickened as in some specimens of P.
chamorrorum (see Remarks below).

The radula of Patelloida chamorrorum clearly distin-
guishes it from other members of the P. profunda group.
No previously recognized member of the P. profunda group
has lateral extensions on the third lateral teeth (Figure
2).

Although the radulae are distinct in all members of this
group, we are impressed by the similarities in both ventral
plate and radular tooth morphologies. The differences be-
tween species in this group are more subtle than occur
in other Patelloidinae (cf PONDER & CREESE, 1980;
LINDBERG, 1983) and in other genera (e.g., Collisella, Lot-
tia, Notoacmea) (cf. MOSKALEV, 1970; PONDER & CREESE,
1980; LINDBERG & MCLEAN, 1981; LINDBERG, 1981).

Remarks: There is inter-island variation in shell char-
acters. Specimens from Tinian are slightly larger (up to
25+ mm long) and have higher profiles than those from
Guam and the more southern islands (Figure 10). These
specimens have shells similar to those of Patelloida conoi-
dalis and P. p. mauritiana. Specimens from the more south-
ern Marianas tend to be lighter in color and have more

The Veliger, Vol. 27, No. 4

Page 414

D. R. Lindberg & G. J. Vermeij, 1985

vivid markings (Figure 11). While these markings are
similar to those of P. calamus and other members of the
P. profunda group (CHRISTIAENS, 1975), they most resem-
ble the Recent New World Patelloida, P. pustulata (Hel-
bling, 1777) and P. semirubida (Dall, 1914).

Juvenile shells of Patelloida chamorrorum have fewer
ribs than the larger shells, and the radial color pattern is
typically present (Figure 12). The intermittent red mark-
ings, which are found on some of the larger shells from
Guam, are readily apparent on juvenile shells. These
markings appear to be identical to the red markings found
on some specimens of P. pustulata from the Caribbean
(Figure 13).

Ecology and biogeography: Patelloida chamorrorum is
an abundant limpet on the middle and upper shore of all
the southern Mariana Islands, where it occupies pits (pre-
sumably of its own making) in the limestone. The chiton
Acanthopleura gemmata (Sowerby, 1825) typically occurs
with P. chamorrorum. We believe that P. chamorrorum
is restricted to limestone shores. The species is not found
on the volcanic shores of southwest Guam (VERMEJJ,
1971), and it is absent from the nine volcanic northern
Mariana Islands (VERMEIJ et al., 1984) (both as Patelloida
Sp.).

Patelloida chamorrorum is one of only a small handful
of marine mollusks that are endemic to the southern Ma-
rianas. The only other confirmed example is the littorinid
Echininus viviparus Rosewater, 1982, which, like P. cha-
morrorum, is an upper-shore species. Echininus viviparus
is chiefly, but not exclusively, on limestone (VERMEJJ, 1971;
ROSEWATER, 1982). Another possible endemic species is
the small neritid Nerita guamensis Quoy & Gaimard, 1834.
This species, or forms very much like it, is distributed in
a disjunct fashion in the Philippines, Fiji, Samoa, the
Ryukyus, the Izu Islands, and the northern and southern
Marianas, and perhaps also the Natal coast of southeast-
ern Africa. Nerita guamensis varies greatly from place to

Page 415

place in the southern Marianas, especially in color, and
lives with £. viviparus on the upper shore. It is striking
that none of the upper-shore endemics of the southern
Marianas are found in, or are closely related, to species
inhabiting the atolls of the Marshall Islands, whose fauna
is in most other respects similar to the Marianas. The
disjunct distribution of the stocks to which the endemics
belong suggests that the Mariana Islands may serve as a
refuge for previously more widespread taxa in the tropical
western Pacific.

DISCUSSION

The recognition of Patelloida chamorrorum in the Ma-
rianas and of its membership to the Patelloida profunda
group caused us to examine closely the anatomical and
shell characters of similar Recent members of the genus
Patelloida and the shell characters of fossil species. From
this work we have recognized additional Recent members
of the P. profunda group in Indonesia, the tropical eastern
Pacific, and Caribbean. Fossil members were identified
from the Paleogene of Europe and the Neogene of the
Caribbean.

In addition to the species listed by CHRISTIAENS (1975)
and Patelloida chamorrorum, we would include Patelloida
sp. (Java and New Guinea) (Figure 14), Patelloida sp.
(Palau Group), Patelloida semirubida (Panamic), and Pa-
telloida pustulata (Caribbean) in the P. profunda group
(Table 1). Fossil members of this group are present in the
Eocene rocks of the Paris Basin (Patelloida centralis [Des-
hayes, 1861] [Figure 15], Patelloida deshayesia nom. nov.
[Figure 16]) and in materials recently collected in the
Dominican Republic by Dr. Peter Jung and colleagues
(Patelloida sp.) (Lindberg, unpublished data). Thus, Re-
cent members of the Patelloida profunda group are distrib-
uted eastward from the east coast of Africa to the Carib-
bean. In the Eocene the group probably extended farther
east to the Paris Basin of France, a clear and definite

Explanation of Figures 1 to 16

Scale bar = 10.0 mm except as noted.

Figures 1 to 4. Patelloida chamorrorum spec. nov. Figure 1.
Holotype, UCMP 37522; Asanite Bay, Guam. Figures 2 and 3.
Radular tooth and lateral plate morphology, LACM 77-16; Pago
Bay, Guam. Scale bar=0.1 mm. Figure 4. Ventral view of
snout; oral lappets (ol), cephalic tentacles (ct), mouth (m) (mu-
seum data same as Figures 2 and 3). Scale bar = 1.0 mm.

Figure 5. Ventral view of snout of Patelloida flammea. Redrawn
from Quoy & GAIMARD (1834; pl. 71, fig. 24). See Figure 4 for
legend. Scale bar = 1.0 mm.

Figures 6 and 7. Patelloida conoidalis, LACM 69206; Henderson
Island, Pitcairn Islands. Figure 6. Shell. Figure 7. Ventral view
of snout. See Figure 4 for legend. Scale bar = 1.0 mm.

Figure 8. Patelloida calamus. Hypotype, UCMP 37524; Tumby
Bay, Australia. Scale bar = 5.0 mm.

Figure 9. Patelloida profunda mauritiana. Hypotype, UCMP
37525; Mauritius.

Figures 10 to 12. Patelloida chamorrorum spec. nov. Figure 10.
LACM 101628; Tinian Island. Figure 11. LACM 20342; Guam.
Figure 12. LACM 77-3; Pago Bay, Guam. Scale bar = 5.0 mm.

Figure 13. Patelloida pustulata. LACM, 35543; Bahama Islands.
Figure 14. Patelloida sp. Hypotype, UCMP 37526; Malinyping,
Java.

Figures 15 and 16. Eocene Patelloida from the Paris Basin,
France. Figure 15. Patelloida centralis. Hypotype, UCMP 37527.
Scale bar = 5.0 mm. Figure 16. Patelloida deshayesia nom. nov.
Hypotype, UCMP 37528. Scale bar = 5 mm.

Page 416

The Veliger, Vol. 27, No. 4

Explanations for Figures 17 and 18

Scale bar = 10.0 mm.
Figure 17. Original illustration of Patelloida conoidalis from PEASE,
1868; pl. 11, fig. 22. Recent, Rarotonga Island, Cook Islands.

Figure 18. Original illustration of Patelloida centralis from
DESHAYES, 1861; pl. 5, fig. 3. Eocene, Paris Basin, France.

Tethyan distribution in space and time (VERMEIJ, 1978:
D2)

We characterize members of the Patelloida profunda
group as having light-colored shells of moderate to high
profile; rounded radial ribs and brown radial markings
are typically present. The Recent species have complex
radular ventral plates with strong lateral processes and
sutures, and the lateral teeth are typically of equal size
and shape. The Recent species are closely associated with
calcareous substrates; members of this group are typically
found on the abundant calcareous substrates and debris
that predominate in tropical nearshore environments.

The fossil species were first identified using shell struc-
ture; all are members of the Patelloidinae and their shell
morphology is identical to Recent members of the Patel-
loida profunda group. On some Eocene specimens from the
Paris Basin, radial color patterns, similar to those of the
Recent species, are still present. However, one of the most
striking examples is seen by comparing the original illus-
tration of the Recent P. conoidalis with the original illus-
tration of the Eocene P. centralis (cf. Figures 17, 18). The
differences that appear in these two illustrations are less
than the intraspecific differences in most Recent species.

The similar shell morphology of members of the Patel-
loida profunda group has been responsible for many of the
misidentifications of the species discussed herein, includ-
ing P. chamorrorum. As stated above, P. chamorrorum
has been most often misidentified as P. conoidalis. This is
also true for other members of this group in the Indo-

Pacific. The Patelloida sp. from Java and New Guinea
has been previously identified as P. conoidalis
(CERNOHORSKY, 1972:38; pl. 6; fig. 5) and CHRISTIAENS
(1980:77) has referred it to “P. conordalis aff.” from Hong
Kong. At this time we have not seen an indisputable spec-
imen of P. conoidalis from any locality farther west than
the Cook Island group (160°W), and we suspect that, as
in the case of P. chamorrorum in the Marianas, each P.
profunda member in a major island group will prove to be
distinct at the specific level. Currently, there is insufficient
material, particularly whole animals, to describe the species
from Java and New Guinea. However, shell characters
do appear to distinguish this species from both P. conor-
dalis and P. chamorrorum. Another member of the P.
profunda group for which there is insufficient material
occurs on limestone cliffs at Urukthapel in the Palau
Group (Vermeij, personal observation). The Palau Group
species has more numerous radial ribs than P. chamor-
rorum.

The presence of a member of the Patellorda profunda
group in the East Indies results in an almost continuous
distribution for this group across the Pacific Ocean and
into the Indian Ocean. However, we are suspicious of the
apparent absence of a member of this group in the more
northern islands of the East Indies (Celebes, Borneo, Phil-
ippines). A possible member in the Philippines may be
‘““Acmaea lentiginosa”’ Reeve, 1855, reported by HIDALGO
(1904) from Marinduque and Mindanao and by FAUSTINO
(1928) from Marinduque and Surigao. We have not seen
any specimens from the Philippines that are similar to
Reeve’s species and his description lacks locality data.

ACKNOWLEDGMENTS

We thank Welton L. Lee (CASIZ), James H. McLean
(LACM), and Robert R. Robertson (ANSP) for provid-
ing loans of material from their respective institutions, and
Mary E. Taylor (UCMP) for preparing Figures 4, 5, and
7. We are grateful to Joseph Christiaens (Hasselt, Bel-
gium) for providing specimens to DRL for comparison
and to Barry Roth (CAS) for furnishing Figure 17. We
also thank Carole S. Hickman, James H. McLean, and
an anonymous reviewer for commenting on the manu-
script. This is contribution no. 207 from the University
of Guam Marine Laboratory.

APPENDIX
Patelloida deshayesia nom. nov.

Figure 16

While preparing this paper, we found that primary hom-
onymy exists between Patella glabra Turton, 1806, and
Patella glabra Deshayes, 1824. Patella glabra TURTON,
1806:572 [vol. 4] is an unrecognizable, unlocalized brown
limpet with white ribs. Patella glabra [DESHAYES, 1824:
10] is an Eocene Patelloida from Paris Basin localities in

D. R. Lindberg & G. J. Vermeij, 1985

France, and a junior primary homonym of P. glabra Tur-
ton, 1806. Therefore, we propose the name Patelloida des-
hayesia nom. nov. to replace Patella glabra Deshayes. The
specific name is in honor of G. P. Deshayes who elo-
quently monographed the limpets (and other mollusks) of
the Paris Basin.

LITERATURE CITED

CERNHORSKY, W. O. 1972. Marine shells of the Pacific, Vol.
2. Pacific Publications: Sydney. 411 pp.

CHRISTIAENS, J. 1975. Révision provisoire des Mollusques
marins récents de la famille des Acmaeidae (seconde partie).
Inform. Soc. Belge Malc. 4:91-116.

CHRISTIAENS, J. 1980. The limpets of Hong Kong with de-
scriptions of seven new species and subspecies. Pp. 61-84.
In: B. Morton (ed.), Proceedings, first international work-
shop on the malacofauna of Hong Kong and southern China.
Univ. Hong Kong Press: Hong Kong.

Cross—, H. & P. FISCHER. 1864. Diagnoses Molluscorum
Australiae meridionalis. J. Conchol. 12:346-350.

DALL, W. H. 1914. Notes on some northwest acmaeas. Nau-
tilus 28:13-15.

DESHAYES, G. P. 1824-1837 [1824]. Description des coquilles
fossiles des environs de Paris. L’auteur, chez Béchet jeune
(etc): Paris. 2 vols., 1 atlas (392 + 814 pp., 166 pls.).

DESHAYES, G. P. 1856-1865 [1861]. Description des animaux
sans vertébres découverts dans le bassin de Paris pour servir
de supplément a la description des coquilles fossiles des en-
virons de Paris comprenant une revue générale de toutes les
espéces actuellement connues. J. B. Bailliére Brothers: Paris.
3 vols., 2 atlases (912 + 968 + 688 pp., 87 + 107 pls.).

DEsHAYES, G. P. 1864. Catalogue des mollusques de ]’Ile de
la Réunion (Bourbon). Dentu: Paris. 144 pp.

FausTIno, L. A. 1928. Summary of Philippine marine and
fresh-water mollusks. Bureau of Printing: Manila. 384 pp.

Forses, E. 1850. On the genera of British patellaceans. Rept.
Brit. Assoc. Adv. Sci. (1849), Part 2:75-76.

Gray, J. E. 1847. A list of genera of Recent Mollusca, their
synonyma and types. Proc. Zool. Soc. Lond. (1847):129-
219.

HEDLEY, C. 1915. Studies on Australian Mollusca Part 12.
Proc. Linn. Soc. N.S.W. 39:695-755.

HELBLING, G.S. 1779. Beitrage zur Kenntniss neuer und sel-
tener Conchylien. K. Ceska spolecnost nauk Prague 4:102-
ISil.

HIDALGO, J. G. 1904. Catalogo de los Moluscos Testaceos de
las Islas Filipinas, Jolo y Marianas I. Moluscos marinos.
Gaceta de Madrid: Madrid. 408 pp.

Page 417

IREDALE, T. 1924. Results from Roy Bell’s molluscan collec-
tions. Proc. Linn. Soc. N.S.W. 49:179-278.

LINDBERG, D. R. 1981. Acmaeidae. Boxwood Press: Pacific
Grove, Calif. 122 pp.

LINDBERG, D. R. 1983. Anatomy, systematics, and evolution
of brooding acmaeid limpets. Ph.D. Thesis, Biology, Univ.
of Calif., Santa Cruz, Calif. 277 pp.

LINDBERG, D. R. & J. H. McLean. 1981. Tropical eastern
Pacific limpets of the family Acmaeidae (Mollusca: Ar-
chaeogastropoda): generic criteria and descriptions of six
new species from the mainland and the Galapagos Islands.
Proc. Calif. Acad. Sci. 42:323-339.

MoskaLev, L. I. 1970. Gastropod molluscs of the genus Col-
lisella (Prosobranchia, Acmaeidae) of the fringing Asian seas
of the Pacific Ocean. Trudy Instituta Okeanologii 88:174-
212 (in Russian).

OLIVER, W. R. B. 1926. Australasian Patelloididae. Trans.
Proc. New Zealand Inst. 56:547-582.

PEASE, W. H. 1868. Descriptions of marine gasteropodae, in-
habiting Polynesia. Amer. J. Conchol. 3:223-230.

Piussry, H. A. 1891. Manual of conchology, Vol. XIII. Ac-
maeidae, Lepetidae, Patellidae, Titiscaniidae. Philadelphia,
Penn. 195 pp.

PONDER, W. F. & R. G. CREESE. 1980. A revision of the
Australian species of Notoacmea, Collisella and Patelloida
(Mollusca: Gastropoda: Acmaeidae). J. Malacol. Soc. Aus-
tral. 4:167-208.

Quoy, J. R. C. & J. P. GaimarD. 1834. Voyage de décou-
vertes de l’Astrolabe, executé par ordre du Roi, pendant les
années 1826-29, sous le commandement de M. J. Dumont
d’Urville. Paris, Zoologie, Mollusca, Vol. 3. 366 pp.

REEVE, L. R. 1854-55. Conchologica iconica, Vol. 8. Mono-
graph of the genus Patella. London. 42 pls.

ROSEWATER, J. 1982. A new species of the genus Echininus
(Mollusca: Littorinidae: Echinininae) with a review of the
subfamily. Proc. Biol. Soc. Wash. 95:67-80.

SMITH, E. A. 1901. On South African marine shells, with de-
scriptions of new species. J. Conchol. 10:104-116.

TurTON, W. 1806. A general system of nature, through the
three grand kingdoms of animals, vegetables, and minerals.
With a life of Linné and a dictionary of explanatory terms

. of natural history, by William Turton. Allen: London.
7 vols.

VERMEJJ, G. J. 1971. Substratum relationships of some trop-
ical Pacific intertidal gastropods. Mar. Biol. 10:315-320.

VERMEIJ, G. J. 1978. Biogeography and adaptation. Harvard
Univ. Press: Cambridge, Mass. 332 pp.

VERMEIJ, G. J., E. A. Kay & L. G. ELDREDGE. 1984. Mol-
luscs of the northern Mariana Islands; with special refer-
ence to the selectivity of oceanic dispersal barriers. Micro-
nesica (in press).

The Veliger 27(4):418-422 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

A New Species of Cuthona from the Gulf of California

by

DAVID W. BEHRENS

Pacific Gas and Electric Co., Biological Research Laboratory,
P.O. Box 117, Avila Beach, California 93424

Abstract.

A new species, Cuthona longi Behrens, from the Gulf of California is described. This

description represents the first occurrence of the genus Cuthona in the Gulf of California.

THE SYSTEMATIC status of Catriona Winckworth, 1941,
Cuthona Alder & Hancock, 1855, and Trinchesia Thering,
1879, has changed several times. The most recent revisions
maintain Cuthona as a valid genus (GOSLINER & GRIF-
FITHS, 1981) and recommend Tergipedidae Thiele, 1931,
as the appropriate family designation (BROWN, 1980).
BEHRENS (1984) reports 14 species of tergipedid nudi-
branchs for the northeastern Pacific, 12 of which are as-
signed to Cuthona. Collections made at Isla Raza, Baja
California by Mr. Jeff Hamann included numerous spec-
imens of a heretofore undescribed tergipedid nudibranch.
To date there have been no cuthonid species reported from
the Gulf of California, although at least two distinct species
are known (J. R. Lance and T. M. Gosliner, personal
communications; present study).

‘TERGIPEDIDAE Thiele, 1931

Cuthona Alder & Hancock, 1855
Cuthona longi Behrens, spec. nov.
(Figures 1 to 6)

Materials examined: (1) Holotype: one specimen ap-
proximately 10 mm long (preserved), collected in 3.1 m
of water at Isla Raza, Baja California, Mexico (28°48’N,
113°0'W) in July 1982 by Jeff Hamann. This specimen
is deposited in the collection of the California Academy of
Sciences, Department of Invertebrate Zoology and Geol-
ogy (CAS), CASIZ 053592.

(2) Paratypes: one specimen, 9 mm long (preserved),
collected concurrently with the holotype is also deposited
in the CAS collection, CASIZ 053593.

(3) One specimen, 10 mm long (preserved) collected
concurrently with the holotype is deposited in the type
collection of Los Angeles County Museum (LACM), Type
Series No. 2085. Color transparencies of living Cuthona
longi are on file at CAS and LACM.

Other material examined: (1) Six specimens, Isla Raza,
Baja California; Jeg. D. W. Behrens, July 1982.

Description: Living animals measured up to 34 mm long.
The body is typically aeolidiform, tapering posteriorly
(Figures 1, 6). The foot is narrow, linear, tapering to a
point posteriorly. The tail is short. The foot corners are
rounded; only slightly laterally produced. The cephalic
tentacles are cylindrical, tapering to a blunt tip and about
Y2 the length of the rhinophores. The rhinophores are
closely set, long, smooth, and tapering to a rounded tip.
The cerata are cylindrical, linear with a conical tip, and
attain a maximum length equal to about % the length of
the rhinophores (Figure 1). They are arranged in thirteen
transverse rows dorsolaterally on the dorsum. The first
row is situated immediately lateral to the rhinophores.
The ceratal half formula from a series of large specimens
is I 3-6, II 4-7, III 4-7, IV 5-8, V 6-7 (prepericardial);
VI 5-6, VII 4-6, VIII 4-5, IX 4-5, X 3-4, XI 3, XII
2, XIII 1-2 (postpericardial). The ceratal arrangement is
shown in Figure 2. The anal pore is anterior to the medial
ceras of the sixth ceratal (first postpericardial) group and
to the right of the pericardial elevation (Figure 2). The
renal pore is just medial to the anal pore. The genital
orifice lies below and between the first and second ceratal
groups on the right side of the body (Figure 2).

The ground color of the body is pale yellow. Irregular
patches of white and pale yellow pigment occur dorso-
medially on the notum, head, and on the anterior surfaces
of the rhinophores and cephalic tentacles. A pale blue
rhomboidal patch occurs on the head, between the eyes
and just posterior to the rhinophores. A smaller triangular
patch of pale blue occurs anterior to and between the
rhinophores. A few pale blue specks occur scattered over
the notum. The distal % of the rhinophores is encrusted
with white pigmentation. The coloration of the cerata is
complex (Figure 1b). The tip of each ceras is white, fol-

D. W. Behrens, 1985

‘\-Yellow-—gold
Pale Blue

Green

Figure 1

a. Dorsal view of Cuthona longi spec. nov., 10 mm in length.
Isla Raza, Baja California. Drawn from color transparency. b.
Ceras of Cuthona longi spec. nov. (Surface specks not shown.)

lowed by a subapical band of red. Below the red band is
a thinner opaque yellow-gold band, followed by a slightly
wider band of pale blue. Below this series of bands, the
liver diverticulum appears granular in nature, fading in
color from dark to light kelly green at the insertion. The
entire surface of each ceras is speckled with opaque white
specks.

The radular formula is 60-89 x 0.1.0. There are no
preradular teeth. Each rachidian tooth is a low horseshoe-
shaped arch, with a deep articulatory socket on the ante-
rior surface on either side (Figure 3). The ceratal cusp
forms a low ridge. There are 5 or 6 strong denticles to
each side of the cusp, the largest being adjacent to the cusp
and the others becoming smaller as they approach the side
of the tooth. The jaws are lightly tinted gold and broadly
oval (Figure 4a). The masticatory border is short with
30-45 irregular nodulous denticles (Figure 4b). In one of
four specimens examined, a series of 3 or 4 hooks occurs
below the non-hinged margin (Figure 4c). This feature,
although probably an artifact, is mentioned because of its
seemingly intentional presence on each plate of the jaw.

The reproductive system is typically cuthonid. The
penial papilla is conical (Figure 5a). After dissection and

Page 419

Figure 2

Diagrammatic right lateral view of the body of Cuthona longi
spec. nov. a, anus; b, genital aperture.

clearing with 0.5 N quaternary ammonium hydroxide it
was found to be unarmed. The ovotestis is massive con-
taining large male acini with numerous smaller, periph-
eral female acini. The ampulla is convoluted. The vas
deferens is short. The egg mass is a white semicircular
coil attached to the substrate at the center of the whorl
(Figure 5b). Its morphology does not fit HuRsT’s (1967)
classification. It is a combination of her Type A and Type
D egg masses. The egg capsules are arranged within the
ribbon in neat repetitive rows, radiating from the center
of the crescent-shaped whorl. The region of attachment is
thin and capsule-free. There were approximately 18-20
egg capsules per row and 50 rows per coil. The egg masses
collected in July 1982 measured about 2.5 mm in diam-
eter and were found on a leafy encrusting bryozoan grow-
ing at the base of a branched plumularid hydroid.

Discussion: Placement of Cuthona longi is based upon the
presence of a non-tapering radula and the absence of a
preradular tooth and penial stylet (GOSLINER & GRIF-

b

Figure 3

Radular teeth of Cuthona longi spec. nov. a, plain view; b, lateral
view.

Page 420

The Veliger, Vol. 27, No. 4

Figure 4

Jaw plate of Cuthona longi spec. nov. a, plain view; b, masticatory edge; c, hooks on margin of jaw.

FITHS, 1981). The species shares characteristics, however,
with members of the genus Catriona, including a radula
with greater than 50 teeth and the presence of bristles on
the masticatory border of the jaw (GOSLINER & GRIF-
FITHS, 1981).

Cuthona longi is the first member of this genus to be
described from the Gulf of California. Very few species
assigned to this genus anywhere in the world exhibit blue
pigmentation. Cuthona caerulea (Montagu, 1804) from the
British Isles bears a brilliant blue ring medially on the
cerata (THOMPSON & BROWN, 1976; BROWN & PICTON,
1979). In C. speciosa (Macnae, 1954) from South Africa
the ceratal epithelium may be bright pale, luminescent
blue (GOSLINER & GRIFFITHS, 1981). In C. ornata Baba,
1937, from Japan the ceratal core is cobalt blue (BABA,

1937). Only C. genovae (O’Donoghue, 1929) from the
Mediterranean bears blue pigmentation on the body sur-
face. In this species the head and prepericardial region is
light blue with a medial white stripe (BOUCHET, 1976).
The cerata also bear blue coloration.

Cuthona longi can be separated from northeastern Pa-
cific species by its distinctive body and ceratal coloration
and by its radula and jaw morphology. Pigmentation on
the head region is not uncommon in Cuthona, as noted for
C. genovae above; however, in the northeastern Pacific no
species bears any pigmentation vaguely resembling that
found on C. longi—a pale blue rhomboid patch on the
head between the eyes and posterior to the rhinophores.
In several species, C. lagunae (O’Donoghue, 1926), C.
perca (Marcus, 1968), C. abronia (MacFarland, 1966), C.

D. W. Behrens, 1985

Figure 5

a. Penis of Cuthona longi spec. nov. b. Egg mass of Cuthona
longi spec. nov. (Not all eggs shown.)

Page 421

albocrusta (MacFarland, 1966), C. flavovulta (Mac-
Farland, 1966), and C. virens (MacFarland, 1966) ceratal
core coloration may be green (BEHRENS, 1980, 1984;
McDOona_p, 1983); however, C. longi differs strikingly
from all the above in the complex surface pigmentation of
three distinct bands of color below a white apical tip, the
opaque gold band being unique to the genus.

The length of the radula is similar to Cuthona albo-
crusta, C. flavovulta, and C. lagunae, having 60-89 teeth,
all other species having shorter radulae (MCDONALD,
1983). The masticatory border of the jaw has a much
greater number of denticles (30-45) than other north-
eastern Pacific species; however, the shape of the denticles
is somewhat similar to those of C. flavovulta, C. fulgens,
and C. lagunae (ROLLER, 1969; McDONALD, 1983).

The specific name longi is chosen to acknowledge the
tireless efforts and scientific contributions of Mr. Steven
J. Long, editor and publisher of Shells and Sea Life, pre-
viously the Opisthobranch Newsletter.

ACKNOWLEDGMENTS

I am grateful to Jeff Hamann for providing me with spec-
imens and distributional data on this species, to Terry
Gosliner for his assistance in differentiating this species

re

~~

Figure 6

Cuthona longi spec. nov., 10 mm in length. Isla Raza, Baja California, Mexico. Photograph by Jeff Hamann.

Page 422

from the dozens of cuthonid species worldwide, and to the
referees for their careful review of the manuscript and
constructive comments.

LITERATURE CITED

Basa, K. 1937. Opisthobranchia of Japan (II). J. Dept. Agric.,
Kyushu Imperial Univ. 5(7):289-346, 2 pls.

BEHRENS, D. W. 1980. Pacific coast nudibranchs: a guide to
the opisthobranchs of the northeastern Pacific. Sea Chal-
lengers: Los Osos, Calif. 112 pp.

BEHRENS, D. W. 1984. Notes on the tergipedid nudibranchs
of the northeastern Pacific with a description of a new species.
Veliger 27(1):65-71.

BoucHET, P. 1976. Trinchesia genonae (O’Donoghue, 1926)
éolidien méconnu du littoral méditerranéen. Vie et Milieu
26:235-242.

Brown, G. H. 1980. The British species of the aeolidacean
family Tergipedidae (Gastropoda: Opisthobranchia) with a
discussion of the genera. Zool. J. Linn. Soc. 69(7):225-255.

Brown, G. H. & B. E. Picron. 1979. Nudibranchs of the

The Veliger, Vol. 27, No. 4

British Isles. Underwater Conservation Soc.: London. 30
PP:

GosLINER T. M. & R. J. GRIFFITHS. 1981. Description and
revision of some South African aeolidacean Nudibranchia
(Mollusca, Gastropoda). Ann. S. Afr. Mus. 84(2):105-150.

Hurst, A. 1967. The egg masses and veligers of thirty north-
east Pacific opisthobranchs. Veliger 9(3):255-288, 13 pls.

McDonaLp, G. 1983. A review of the nudibranchs of the
California coast. Malacologia 24(1-2):114-276.

MILLER, M. C. 1971. Aeolid nudibranchs (Gastropoda: Opis-
thobranchia) of the family Tergipedidae from New Zealand
waters. Zool. J. Linn. Soc. 60(3):197-222, 1 pl.

O’DonocHuE, C. H. O. 1929. Report on the Opisthobran-
chiata (in) Zoological results of the Cambridge Expedition
to the Suez Canal. Trans. Zool. Soc. Lond. 22(6)9:713-841.

ROLLER, R. A. 1969. Nomenclatural changes for the new species
assigned to Cratena by MacFarland, 1966. Veliger 11(4):
421-423.

TuHompson, T. E. & G. H. Brown. 1976. British opistho-
branch molluscs. Synopses of the British Fauna. (New se-
ries) No. 8. Academic Press: London. 203 pp.

THE VELIGER

© CMS, Inc., 1985
The Veliger 27(4):423-429 (April 1, 1985)

Three New Species of Lepidozona
(Mollusca: Polyplacophora)
from the Gulf of California

by

ANTONIO J. FERREIRA!

Research Associate, Department of Invertebrate Zoology, California Academy of Sciences,
Golden Gate Park, San Francisco, California 94118

Abstract. The number of species of Lepidozona endemic to the Gulf of California, Mexico, is raised
to nine with the descriptions of three new ones, L. lawrae, L. macleaniana, and L. stohleri, from the

subtidal zone. A diagnostic key to the species of Lepzdozona in the Gulf of California is given.

THE GENUS Lepidozona Pilsbry, 1892, is remarkably well
represented in the northeastern Pacific. To the eight species
already recognized in the temperate region (FERREIRA,
1978), and six others in tropical waters (FERREIRA, 1974),
three new ones are added here to the fauna of the Gulf of
California, raising to nine the number of Lepidozona species
in the Panamic Province, and to seventeen the number in
the northeastern Pacific.

Class Polyplacophora Gray, 1821
Order Neoloricata Bergenhayn, 1955
Suborder Ischnochitonina Bergenhayn, 1930
Family Ischnochitonidae Dall, 1889
Genus Lepidozona Pilsbry, 1892

Type-species: Chiton mertensi: Middendorff, 1847, by
original designation (PILSBRY, 1892).

Lepidozona laurae Ferreira, spec. nov.

(Figures 1 to 5)

Diagnosis: Small (largest, 14.5 mm long) chitons, rusty
brown, carinate, not beaked. Anterior valve, lateral areas
of intermediate valves, and postmucro area of posterior
valve with very faint radial riblets, and minute, round
tubercles (up to 80 wm in diameter); central areas with
longitudinal rows of granules coalescing into riblets, par-

‘For reprints: 2060 Clarmar Way, San Jose, California 95128.

allel to jugum, vaguely latticed; mucro anterior. Girdle
with imbricate, striated scales. Radula with unicuspid ma-
jor lateral teeth.

Type material: Holotype and one paratype at the Cal-
ifornia Academy of Sciences (CAS 050245 and CAS
050244, respectively); six other paratypes at the Los An-
geles County Museum of Natural History (LACM 2003),
United States National Museum of Natural History
(USNM 820460), Academy of Natural Sciences of Phila-
delphia (ANSP 358901), and in the private collections of
Laura and Carl Shy, Seal Beach, California, and Antonio
J. Ferreira.

Type locality: 3.2 km southeast of San Antonio, Guay-
mas, Sonora, Mexico (27°57'N, 111°06’W), at 73-91 m
(leg. Laura and Carl Shy, dredged Oct. 1977 and Oct.
1979).

Other material: 5 km south of Tetas de Cabra, Sonora,
Mexico, dredged at 60-90 m, 2 specimens, largest 14 mm
long (Skoglund Coll., leg. C. & P. Skoglund, Nov. 1979);
5 km southeast of Punta San Antonio, Guaymas, Sonora,
Mexico, dredged at 100 m, 1 specimen, 14.5 mm long
(Poorman Coll., leg. F. & L. Poorman, Apr. and Oct.
1983).

Description: Holotype (Figure 1), preserved flat in al-
cohol, 11.0 mm long, 6.5 mm wide (including girdle), 2.0
mm high; valves carinate, moderately elevated, posterior
edge straight, not beaked; tegmentum microgranular. Lat-
eral areas slightly elevated with 5-6 very faint radial rib-
lets with minute (60-80 um in diameter), round tubercles

Page 424

The Veliger, Vol. 27, No. 4

Explanation of Figures 1 and 2

Figure 1. Lepidozona laurae Ferreira, spec. nov.: Holotype (CAS
050245).

(see Figure 2, paratype); anterior valve with some 25
similar radial riblets and tubercles; central areas with lon-
gitudinal rows of granules, mostly coalesced into 12 riblets
per side, vaguely latticed, and parallel to, but obsolete at
jugum; on valve 11, few jugal riblets diverge in manner
similar, although attenuated, to the wedgelike pattern seen
in other species of Lepidozona (FERREIRA, 1974); mucro
anterior; postmucro slightly concave with radial riblets
and tubercles. Gills holobranchial, extending along 90%
of foot’s length, 20 plumes per side.

Paratype, 10.5 mm long, disarticulated: articulamen-
tum white; slit formula, 10-1-11; insertion teeth sharp;

Figure 3

Lepidozona laurae Ferreira, spec. nov.: Paratype (Ferreira Coll.);
scale of girdle’s upper surface.

Figure 2. Lepidozona laurae Ferreira, spec. nov.: Paratype, 13
mm long (Shy Coll.); close up of lateral areas of intermediate
valves.

eaves solid; sutural plates subrectangular; sinus well de-
fined; on valve viii, relative width of sinus (width of sinus/
width of sutural plates), 0.4. Width of valve i/width of
valve viii, 1.1. Girdle’s upper surface covered with imbri-
cate scales, up to 160 wm in length (smaller at inner and
outer margins), with some 10 shallow striations (Figure
3); girdle’s undersurface covered with elongate, transpar-
ent, rectangular scales, 40-80 wm long, 12 um wide, ar-
ranged in columns as if articulated end-to-end (Figure 4).
Radula (very similar to that of L. mertensi and other
Lepidozona species [cf. fig. 34 in FERREIRA, 1978]), 3.5

_._100um _,

Figure 4

Lepidozona laurae Ferreira, spec. nov.: Paratype (Ferreira Coll.);
scales of girdle’s undersurface.

A. J. Ferreira, 1985

100um_,

Page 425

Figure 5

Lepidozona laurae Ferreira, spec. nov.: Paratype (Ferreira Coll.); radula’s median, first lateral, and major lateral

teeth.

mm long (33% of specimen’s length), with 25 rows of
mature teeth; median tooth enlarged at anterior blade, 80
pm wide, narrowing sharply posteriorly; first lateral teeth
subrectangular, with explicit knob at antero-outer corner;
major lateral teeth with unicuspid head, 70 um wide, and
unusually long and thin subcapital tubercle (Figure 5);
outer marginal teeth elongate, 110 x 70 um.

Distribution: Lepidozona laurae is known only from the
general locality of Guaymas, Sonora, Mexico, and depths
of 60-100 m.

Remarks: For its striated scales, Lepidozona laurae may
be grouped with the sympatric congenerics L. serrata
(Carpenter, 1864), L. allynsmithi Ferreira, 1974, L. crock-
ert (Willett, 1951), and L. subtilis Berry, 1956, from which
it differs in sculptural features, size, color, and habitat
(see FERREIRA, 1974). Because of its small size, and rel-
atively deep-water habitat, rusty brown specimens of L.
laurae, with small round tubercles on lateral areas and
end valves, may be confused with L. retiporosa (Carpenter,
1864) known from similar latitudes in the outer (Pacific)
colder side of Baja California; however, the two species
differ distinctly in the tegmental sculpture of the central
areas (granulose longitudinal riblets in lawrae; quincun-
cial, netlike pits in retiporosa).

The species is here designated laurae after Laura Shy,
Seal Beach, California, who, with her husband, Carl L.
Shy, collected and kindly made available specimens for
study.

Lepidozona macleamiana Ferreira, spec. nov.
(Figures 6 to 10)

Diagnosis: Medium size (20 mm long) chiton, carinate,
mottled cream-brown. Radial ribs flat, close together,

mostly smooth on lateral areas, irregularly granulose on
end valves. Central areas with parallel, latticed, longitu-
dinal riblets; jugum ribbed, with wedgelike pattern on
valve ii. Mucro central. Girdle scales large, convex, smooth,
nippled.

Type material: Holotype (LACM 2004).

Type locality: Off San Pedro Nolasco Island, Gulf of
California, Mexico (27°58'32”N, 111°23'37”W), at 100-
104 m (ex LACM-AHF 1085-40, 6 Feb. 1940).

Description: Holotype (Figures 6, 7, 8, 9), preserved in
alcohol, valves iii-vii broken but in place; estimated length
20 mm long, width 10 mm, height 4 mm; valves carinate,
not beaked; jugal angle about 110°; tegmentum micro-
granular, mottled cream-brown. Anterior valve with 30
radial flattish to subgranulose ribs, close together. Lateral
areas with 6-8 radial ribs, similar to those on anterior
valve, except for appearing much more decidedly flat, not
granulose. Central areas with longitudinal riblets, parallel
to jugum, 16 per side, about 70 um thick, 150 um apart,
clearly latticed near jugum, but only obsoletely so in pleu-
ral areas; jugal areas ribbed, with wedgelike pattern on
valve ii. Mucro central, postmucro area slightly concave
with some 30 radial, flattish ribs. Articulamentum white
with brown discoloration at apex of valves. Insertion teeth
sharp, well formed; slits 12-1-12, followed by slit-rays;
sutural laminae relatively short, subrectangular; sinus well
defined; on valve viii, relative width of sinus, 0.3; width
of valve i/width of valve viii, 1.1. Gills holobranchial,
about 30 plumes per side. Girdle’s upper surface covered
with imbricate, strongly convex scales, up to 200 wm in
length, some displaying nipplelike formation on dorsal
edge (Figure 10); undersurface paved with transparent,
rectangular scales, 60-80 um long, 12 um wide, arranged

The Veliger, Vol. 27, No. 4

Page 426

A

x:

vib

we

4, 4 o #®.

,

Ed

id

“

zee >.

A. J. Ferreira, 1985

Figure 10

Lepidozona macleamiana Ferreira, spec. nov.: Holotype (LACM
2004); scale of girdle’s upper surface.

end-to-end, in columns (as in Lepidozona laurae). Radula,
not examined.

Distribution: Lepidozona macleamana is known only from
the type locality.

Remarks: For its stongly convex girdle scales, Lepidozona
macleaniana resembles L. formosa from which it differs
in tegmental sculpture (radial ribs of lateral areas flattish
in macleaniana, distinctly tuberculate in formosa).

The species is here named macleaniana after Dr. James
H. McLean, Los Angeles County Museum of Natural
History, who has generously provided this and many
other specimens for study.

Lepidozona stohleri Ferreira, spec. nov.
(Figures 11 to 14)

Diagnosis: Medium size (largest, 26 mm long) chitons,
carinate, mostly brown-orange colored. Lateral areas and
end valves with radial rows of small (to 200 wm), round
tubercles. Central areas with longitudinal, parallel riblets,
latticed: jugum ribbed, showing wedgelike pattern of rib-

Page 427

100um

Figure 13

Lepidozona stohleri Ferreira, spec. nov.: Paratype (Ferreira Coll.);
scale of girdle’s upper surface.

lets on valve 11; mucro central. Girdle with large, smooth,
convex, nippled scales.

Type material: Holotype (CAS 050246), and 16 para-
types (CAS 050247; LACM 2005; USNM _ 820459; ANSP
358902; and in the private collections of Laura and Carl
Shy, and Antonio J. Ferreira).

Type locality: Smith Id., Bahia de Los Angeles, Gulf of
California, Baja California, Mexico (29°02'N, 113°30’W),
at 12-36 m (leg. Laura & Carl Shy, dredging, west side
and south side of Smith Id., May 1975 and May 1976).

Other material: Puerto Refugio, Angel de la Guarda Id.,
Gulf of California, Mexico, 1 specimen, at 20-40 m
(LACM-AHF 1048-40); Danzante Id., Gulf of Califor-
nia, Mexico, dredged at 30-60 m, 3 specimens, maximum
18 mm long (Shy Coll., leg. L. & P. Shy, Oct. 1982);
Bahia de los Angeles, Baja California, Mexico, dredged
at 21-50 m, 4 specimens, largest 18 mm long (Skoglund
Coll., leg. C. & P. Skoglund, May 1976; Poorman Coll.,
leg. F. & L. Poorman, May 1976).

Description: Holotype (Figures 11, 12), preserved dry,
flat, 20.5 mm long, 13 mm wide, uniformly orange. Valves
carinate, not beaked, jugal angle 120°. Tegmentum mi-
crogranular. Anterior valve with 35 radial rows of round,
discrete tubercles, about 100 wm in diameter (smaller to

Explanation of Figures 6 to 9, 11, and 12

type (LACM 2004); close up of valves ii and iii.

Figure 7. Lepidozona macleaniana Ferreira, spec. nov.: Holo-
type (LACM 2004); close up of lateral areas of intermediate
valves.

poe! 6. Lepidozona macleaniana Ferreira, spec. nov.: Holo-

Figure 8. Lepidozona macleaniana Ferreira, spec. nov.: Holo-
type (LACM 2004); valves i and viii, tegmental surfaces.

Figure 9. Lepidozona macleaniana Ferreira, spec. nov.: Holo-
type (LACM 2004); valves i and viii, articulamental surfaces.

Figure 11. Lepidozona stohleri Ferreira, spec. nov.: Holotype
(CAS 050246).

Figure 12. Lepidozona stohleri Ferreira, spec. nov.: Holotype
(CAS 050246); close up of lateral areas of intermediate valves.

Page 428

The Veliger, Vol. 27, No. 4

o LOOM E:

Figure 14

Lepidozona stohleri Ferreira, spec. nov.: Paratype (Ferreira Coll.); radula’s median, first lateral and major lateral

teeth.

50 um centrally, larger to 200 um at periphery), 100-150
um apart. Lateral areas with 5-6 similar rows of tuber-
cles; sutural edges irregularly crenulate by tubercles. Cen-
tral areas with longitudinal riblets, 15-18 per side, par-
allel to jugum, 70 wm thick, 150 um apart, latticed. Jugal
areas, ribbed; riblets forming wedgelike pattern on valve
ii. Mucro central; postmucral area somewhat convex, with
some 20 similar radial rows of tubercles. Girdle’s upper
surface with imbricate, strongly convex scales, up to 200
um in length, some showing nipplelike formation on dor-
sal edge (Figure 13); undersurface paved with transpar-
ent, rectangular scales, 60-80 wm in length, 10 wm in
width, arranged end-to-end, in columns (as in Lepidozona
laurae).

Paratypes uniformly brown-orange, except one with
black pleural areas and white jugal stripe; none with red.
Largest 26 mm long; width/length, mean = 0.63 (n = 10;
SD = 0.05). Disarticulated paratype, 9.5 mm long; arti-
culamentum, white; sutural laminae relatively short, sub-
rectangular; insertion teeth well formed, sharp; slits 11-
1-12, followed by slit-rays. On valve viii, relative width
of sinus, 0.4; width of valve i/width of valve viii, 1.2. Gills
holobranchial, about 20 plumes per side. Girdle, as in
holotype. Radula, 4.2 mm long (44% of specimen’s length),
comprising 24 rows of mature teeth; median tooth 105 wm
at anterior blade, narrowing posteriorly; first lateral teeth,
subrectangular, 150 um long, with large knob at antero-
outer angle; major lateral teeth with unicuspid head, and
subcapital tubercle long and thin (as in Lepidozona lau-
rae, 37 x 15 um (Figure 14); outer marginal teeth, elon-
gate, 150 x 75 um.

Other material as above; one specimen from Danzante
Id., and three specimens from Bahia de los Angeles with
same black-white color pattern seen in one of the para-

types.

Distribution: Lepidozona stohleri is known only from Ba-
hia de Los Angeles (type locality), Puerto Refugio, Angel
de la Guarda Id. (29°32'33”N, 113°33’57”W), and Dan-
zante Id., Baja California, Mexico (25°46’N, 111°15'W),
at depths of 12-36 m to 30-60 m.

Remarks: Lepidozona stohlert may be confused with L.
formosa Ferreira, 1974, from which it differs in the char-
acteristics of the tubercles on lateral areas and end valves
(coarsely defined, coalesced, like varices on the radial rib-
lets in formosa; well defined, discrete, round, only occa-
sionally coalesced in stohleri); in addition, the reddish
hues often present in L. formosa have not been seen in L.
stohleri.

On account of its large, convex, nippled girdle scales,
Lepidozona stohleri belongs, with L. macleamiana, in the
group of L. clathrata (Reeve, 1847) (see FERREIRA, 1974).
Articulamentum and radula being identical, it is the pres-
ence of discrete tubercles on lateral areas and end valves
that distinguishes it from these congenerics in the Gulf of
California. It also resembles the warm-temperate L. mer-
tensu (Middendorff, 1847) and L. guadalupensis Ferreira,
1974; differential characteristics are found in the radial
rows of tubercles on the anterior valve (about 35 rows,
close together in stohleri; about 20 rows, well apart in
mertensui and guadalupensis) and, similarly, on lateral areas.

The species is here named stohleri after Dr. Rudolf

JX. \\o ores UYKes)

Stohler, Research Zoologist Emeritus, University of Cal-
ifornia, Berkeley, California, founder and former Editor
of The Veliger, to whom Californian malacologists will be
forever indebted.

DISCUSSION

In addition to the three species here described, six other
species of Lepidozona—L. clathrata (Reeve, 1847), L. ser-
rata (Carpenter, 1864), L. crocker: (Willett, in Hertlein
& Strong, 1951), L. subtilis Berry, 1956, L. allynsmithi
Ferreira, 1974, and L. formosa Ferreira, 1974—are rec-
ognized in the Gulf of California, all endemic to the re-
gion. To facilitate their identification, the following key is
given.

Key to the Species of Lepidozona in
the Gulf of California

1. Girdle scales

-large, convex, smooth, nippled .............. D>

-small, flattish, striated, not-nippled .......... 5
2. Radial ribs in lateral areas and end valves

SWTMCUDERCLES iawn ans sn Ghivitanue te tagtetiate ae ot 3

SMC MSIMOOLMG Se aie 2 ee cee esky + L. macleaniana
3. Tubercles

—coalesced, like varices on rib ............... 4

-discrete, semispherical .............. L. stohleri

4. Radial ribs (and color of specimens)
-well apart, tubercles mostly elongate (specimens
in dingy brown to greenish-gray tones) ......
> 0 10 “4 wii0''020:579 BANS ROS aeer i eee ene L. clathrata
-close together, tubercles mostly round (specimens

in bright, reddish tones) ............. L. formosa

5. End valves and lateral areas
SWAT OUtEtUDERCLESH Mee cao een foe 6
=WnUn MOSES coos oncosaoedheoooueeoeoun subs 8

6. Radial ribs
-of minute beads (5-8 riblets per lateral area) . .

J! o caer etlawe cs MeNgaae aR Entel le ae Reet ead i L. subtilis
-flattened (2-4 per lateral area) .............. 7

7. Central areas riblets
-longitudinal, latticed ................. L. serrata

-crossed at oblique angles, forming lozenges
rn Ae ein ia a are Woo gy hang L. allynsmithi
8. Tubercles
-coalesced, like varices on rib .......... L. crockert
=—GSCREIS, inowinel S.soaaoneenbnieneeeon- L. laurae

Page 429

ACKNOWLEDGMENTS

For their help and assistance, appreciation is here ex-
pressed to Laura and Carl L. Shy, Seal Beach, California;
Carol and Paul E. Skoglund, Phoenix, Arizona; Forrest
and Leroy Poorman, Westminster, California; Dr. James
H. McLean, Los Angeles County Museum of Natural
History; and Dr. Peter U. Rodda, California Academy of
Sciences, San Francisco, California.

LITERATURE CITED

BERGENHAYN, J. R. M. 1930. Kurze Bemerkungen zur Kennt-
nis der Schalenstruktur und Systematik der Loricaten. Kungl.
Svenska Vetensk. Handl. (3)9(3):3-54, 5 text figs., 10 pls.

BERGENHAYN, J. R. M. 1955. Die fossilen schwedischen Lo-
ricaten nebst einer vorlaufigen Revision des Systems der
ganzen Klasse Loricata. Lunds Universitets Arsskrift. Avd.
2, 5(8):1-43, Kungl. Fysiogr. Sallsk. Handl. N.F. 66(8):3-
42, 2 tables.

Berry, S. S. 1917. Notes on west American chitons. I. Proc.
Calif. Acad. Sci. (4)7(10):229-248, 4 text figs.

Berry, 8. S. 1956. Diagnoses of new eastern Pacific chitons.
Leaflets in Malacology 1(13):71-74

CARPENTER, P. P. 1864. Diagnoses of new forms of mollusks
collected at Cape St. Lucas by Mr. J. Xantus. Ann. Magaz.
Natur. Hist. (3)13:311-315.

DaLL, W. H. 1889. Preliminary catalogue of the shell-bearing
marine mollusks and brachiopods of the southeastern coast
of the United States, with illustrations of many of the species.
Bull. U.S. Natl. Mus. 37:3-271, 74 pls.

FERREIRA, A. J. 1974. The genus Lepidozona in the Panamic
Province, with the description of two new species (Mollusca:
Polyplacophora). Veliger 17(2):162-180, 6 pls.

FERREIRA, A. J. 1978. The genus Lepidozona (Mollusca: Poly-
placophora) in the temperate eastern Pacific, Baja Califor-
nia to Alaska, with the description of a new species. Veliger
21(1):19-44, 3 text figs., 5 pls.

Gray, J. E. 1821. A natural arrangement of Mollusca, ac-
cording to their internal structure. London Med. Repos. 15:
229-239.

MIpDpDENDoRFF, A. T. VON. 1847. Vorladufige Anzeige bisher
unbekannter Mollusken, als Vorarbeit zu einer Malaco-
zoologia Rossica. Bull. Classe Phys.-Math. Acad. Imp. Sci.
St. Petersbourg No. 128, 6(8):113-122

Pitssry, H. A. 1892. Polyplacophora. In: G. W. Tryon Jr.
(ed.), Manual of conchology, 14:209-350 + i-xxxiv, pls. 41-
68.

REEVE, L. A. 1847. Monograph of the genus Chiton. In: Con-
chologia iconica, or Illustrations of the shells of molluscous
animals. London. 4:28 pls., 194 figs.

WILLETT, G. 1951. Jn: L. G. Hertlein & A. M. Strong, East-
ern Pacific expedition of the New York Zoological Society,
XLIII. Mollusks from the west coast of Mexico and Central
America. Part X. Zoologica. 36:67-120, pls. 1-10

The Veliger 27(4):430-439 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

Review of the West Coast Aspelloids Aspella and

Dermomurex (Gastropoda: Muricidae), with the

Descriptions of ‘Two New Species

EMILY H. VOKES

Department of Geology, Tulane University, New Orleans, Louisiana 70118

Abstract. The ten known representatives of two closely related muricid genera, Aspella (four species)
and Dermomurex (six species), living on the west coast of tropical America are discussed and figured.
In Aspella these taxa include A. pyramidalis, hastula, and pollux. In Dermomurex the taxa are D. obeliscus,
indentatus, bakeri, cunninghamae, and myrakeenae. In addition, two new species known only from
Panama are described: Aspella strepta and Dermomurex gunteri. Several Atlantic cognate species are

also figured for comparison.

ONE WOULD THINK that the shallow-water molluscan fau-
na of tropical west America is among the best known in
the world. But such is not the case; in the dozen years
after KEEN published the second edition of Sea Shells of
Tropical West America (1971) six new species of Murici-
dae alone were added (VOKES, 1983). The family Muric-
idae is a prominent part of the shallow-water fauna with
almost 100 species. A relatively important member of this
group is the genus Dermomurex, which until now had five
known species; this paper adds a sixth. The genus Aspella
has now four known species, with the addition of the new
species described herein; no other geographic region ex-
cept the western Atlantic has as many representatives of
this small, and often overlooked, genus. Not only are there
numerous species of Aspella and Dermomurex on the west
coast of tropical America but there is an unusually large
number of cognate species between the Atlantic and Pa-
cific faunas.' Table 1 lists these parallel forms.

Both Aspella and Dermomurex normally occur in very
shallow water, frequently under stones at low tide; only

‘In the family Muricidae, other than the aspelloids and ex-
cluding the subfamily Trophoninae, which is too poorly known
to be discussed, in the tropical western Atlantic (Florida to
northern Brazil) there are 99 species; in the tropical eastern
Pacific (the area of Keen’s study) there are 86 species. Of this
number only 29 may be considered cognates (see VOKES, 1984,
for more details).

the subgenus Dermomurex (Trialatella) occurs in offshore
waters but the depth is still only about 60 m. This shal-
low-water habitat should mean that all forms had already
been discovered; therefore, it was somewhat of a surprise
recently to be given material from the Pacific coast of
Panama of what proved to be two new species of aspelloid.

The term “‘aspelloid” is an appellation, coined by me,
to indicate the two genera Aspella and Dermomurex, which
are united in having an extremely thick, deciduous, chalky
outer layer. This peculiar layer, the intritacalx (D’ATTI-
LIO & RADWIN, 1971), although not unique to the aspel-
loids, is not nearly as well developed in any other group,
indicating that these two are more closely related to each
other than to any other groups.

For many years Dermomurex was considered a subge-
nus of Aspella (e.g., KEEN, 1971:527) but work on their
geologic history (VOKES, 1975) revealed a long separate
development (back to the Oligocene) as well as several
divisions that needed to be recognized within Dermomu-
rex. The result is that Aspella is restricted to the nominate
subgenus, with only 17 described species (fossil and Re-
cent). Dermomurex, in contrast, is assigned five subgenera.
The genus was discussed in a previous work (VOKES, 1975)
and it was noted that there were 32 species, fossil and
Recent, to be divided among these five subgenera. But,
since that time, four additional Recent species have been
added to the list: D. alabastrum (Adams) (see VOKES, 1976)
and D. oxum Petuch (1979), both from the western At-

E. H. Vokes, 1985

lantic; D. africanus Vokes, 1978, from East Africa; and D.
bobyini (Kosuge, 1984). The one described herein adds a
fifth.

In addition to these Recent species I have in press two
other papers in which a total of eleven species will be
added: seven from Australia (two Recent and five fossil)
and four fossils from the Dominican Republic. Thus, in
less than ten years the number of taxa recognized has
increased from 32 species to 48.

The same sort of development also can be seen in As-
pella with the description of seven new species of Aspella
by RADWIN & D°ATTILIO (1976:219-228) almost dou-
bling the total count in one stroke. One additional species,
A. vokesiana, from Madagascar, has since been described
by HouartT (1983).

SYSTEMATIC DESCRIPTIONS
Family MurRIcIDAE Da Costa, 1776
Subfamily MurRIcINAE Da Costa, 1776
Genus Aspella Morch, 1877

Aspella MORCH, 1877:24.

Type-species: Ranella anceps Lamarck, 1822, by mono-
typy-

Discussion: The genus Asfella is based upon a species of
unknown provenance named by Lamarck as “Ranella”
anceps. As members of the genus are so often, the original
specimen is beach-worn, so that identification of the species
is impossible. Originally it was confounded with the west
coast A. pyramidalis (Broderip), but the latter is one of the
few Aspella species that cannot be confused with A. anceps,
due to its color pattern.

I formerly (VOKES, 1975, 1978) considered Aspella an-
ceps to be the species later described as A. acuticostata
(Turton, 1932), from South Africa, which I thought also
occurred in Australia (the latter subsequently described
as A. pondert by RADWIN & D’ATTILIO, 1976).

Since that time Winston Ponder, of the Australian Mu-
seum, has located Lamarck’s type specimen, which is in
the Geneva Museum and, although it did not solve the
problem, it did eliminate some of the contenders. Assum-
ing it is one of the described species, we may compare it
with the following: Aspella acuticostata (Turton, 1932),
from South Africa; and A. ponder: (Australia), mauritana
(Mauritius), cryptica (Brazil), and platylaevis (Indo-Pa-
cific, in general), all of Radwin & D/’Attilio, 1976. Of
these, acuticostata, mauritana, and cryptica are all too small,
as the type is about 14 mm in height. The Australian A.
ponder: is a possibility at just under 14 mm, but the most
likely candidate seems to be A. platylaevis. It is the largest
species with the proper shape (1.e., a narrow shell unlike
the more alate, larger species, such as A. producta) and it
has the most widespread distribution, being known from
Western Australia and Palau, to the Philippine Islands

Page 431

Table 1

Atlantic-Pacific cognate species of aspelloids.

Pacific form Atlantic form

Aspella

A. cryptica Radwin & D?Attilio
A. morchi Radwin & D?Attilio

A. pyramidalis (Broderip)

A. hastula (Reeve)

A, pollux Radwin &

D’Attilio A. castor Radwin & D’Attilio
— A. senex Dall

. Strepta, spec. nov. —

a

Dermomurex

D. obeliscus (A. Adams) D. pauperculus (C. B. Adams)
D. indentatus (Carpenter) D. alabastrum (A. Adams)
D. guntert, spec. nov. —
D. bakeri (Hertlein &

Strong) D. elizabethae (McGinty)
D. cunninghamae (Berry) D. abyssicola (Crosse)

— D. oxum Petuch

D. myrakeenae (Emerson

& D?’ Attilio) —

and French Polynesia (Rangiroa and Tahiti—Vokes
Coll.). Thus, A. platylaevis seems the most likely candidate
for identification as Lamarck’s species. However, as RAD-
WIN & D’ATTILIO state (1976:21), whatever species might
ultimately be proven to be the “real” A. anceps, nothing
would be changed in the generic concept of Aspella, so
similar are all the forms.

Aspella pyramidalis (Broderip, 1833)
(Figures 1-3)

Ranella pyramidalis BRODERIP, 1833:194: SOWERBY, 1835:
pl. 84, fig. 2.

Ranella anceps Lamarck: KIENER, 1842:37 (locality data only)
not pl. 4, fig. 2 (? = type specimen of anceps); REEVE,
1844a:pl. 8, fig. 43 (not of Lamarck).

Aspella (Aspella) pyramidalis (Broderip): KEEN, 1958b:364,
not fig. 376 (=A. pollux Radwin & D’Attilio); KEEN,
1971:527, fig. 1013 (syntypes, British Museum).

Aspella pyramidalis (Broderip): VOKES, 1975:125, pl. 1, figs.
10-13; RADWIN & D’ATTILIO, 1976:23, pl. 1, figs. 4-
6 only; text figs. 7 (intritacalx), 8 (radula); Fair, 1976:
70, pl. 16, figs. 205-207.

Discussion: Aspella pyramidalis is by far the most common
species of Aspella on the tropical west coast, ranging from
Mazatlan, Mexico, to Panama (Vokes Coll.), and as far
south as Colombia (fide RADWIN & D’ATTILIO, 1976:25).
This distribution is undoubtedly a reflection of the longer
larval stage indicated by the three and three-quarter whorl
protoconch, which in Aspella is unique to A. pyramidalis.
All other species have paucispiral protoconchs. It has been
cited from the Galapagos, but (so far as I know) all spec-
imens taken there are to be referred to A. hastula, which
follows.

Page 432
Aspella hastula (Reeve, 1844)
(Figure 4)
Ranella hastula REEVE, 1844a:pl. 8, fig. 42; REEVE, 1844b:
139.

Aspella pyramidalis (Broderip): HERTLEIN & STRONG, 1939:
369, pl. 32, figs. 10, 13 (not of Broderip).

Aspella (Aspella) hastula (Reeve): KEEN, 1971:527, fig. 1012.

Aspella hastula (Reeve): VOKES, 1975:126, pl. 1, fig. 8; Farr,
1976:47, pl. 16, fig. 208.

Aspella pyramidalis (Broderip): RADWIN & D’ATTILIO, 1976:
24, in part, pl. 1, figs. 7, 8 only.

Discussion: This species is sometimes included with As-
pella pyramidalis; however, it may be distinguished by the
spiral rows of nodes or granulations that mark the shell.
RADWIN & D’ATTILIO (1976:24) believed that Reeve’s
illustration was of the mainland form (A. pyramidalis).
This seems unlikely for two reasons: one, Reeve specifi-
cally mentioned that the shell is “transversely granulately
striated,” and, two, he compared it with “Ranella anceps”
(which to him was A. pyramidalis) stating that it is “less
pyramidal” although similar to that species. It seems ob-
vious that he was distinguishing between the two west
American species.

Although Reeve gave no locality for the species he named
“R.” hastula, it is almost certainly the Galapagos snail, as
this is the only living species known that has granulations
(there is one [?]unnamed European Miocene form that
is granulated). Granules are also shown in the specimen
illustrated by HERTLEIN & STRONG (1939:pl. 32, fig. 10)

The Veliger, Vol. 27, No. 4

said to come from the Pleistocene raised beach on San
Salvador Island (James), Galapagos.

Aspella pollux Radwin & D’Attilio, 1976
(Figure 5)

Aspella (Aspella) pyramidalis (Broderip): KEEN, 1958b:364,
in part, fig. 376 only.

Aspella cf. A. pyramidalis (Broderip): D’ATTILIO & RADWIN,
1971:356, fig. 4 (intritacalx).

Aspella sp.: VOKES, 1975:126, pl. 1, fig. 9; Farr, 1976: 88,
pl. 16, fig. 211.

Aspella pollux RADWIN & D’ATTILIO, 1976:225, pl. 1, figs.
3, 29, text-figs. 172 (intritacalx), 173 (radula).

Discussion: This species, which has only recently been
recognized as distinct from the more abundant Aspella
pyramidalis, is the eastern Pacific equivalent of A. producta
in the Indo-Pacific, with a much larger and wider shell
form. RADWIN & D’ATTILIO (1976:226) note that it is
found from the Gulf of California:to Costa Rica, but as
yet it has not been taken in Panama or farther south.

Aspella strepta E. H. Vokes, spec. nov.
(Figures 6, 7)

Description: Shell small, six teleoconch whorls, proto-
conch unknown. On first postnuclear whorl six rounded
axial ridges; by third postnuclear whorl two of these
strengthened into small varices on opposite sides of the
shell, with a second set of weaker ribs formed from the

Explanation of Figures 1 to 14

Figures 1, 2, 3. Aspella pyramidalis (Broderip). Locality of all:
TU R-166, Barra de Navidad, Jalisco, Mexico.

Figure 1. (x3). USNM 739569; height 13.5 mm, diameter
5.7 mm. With intritacalx present.
Figure 2. (x3). USNM 739569; height 12.7 mm, diameter
5.5 mm. With intritacalx removed, showing underlying color
pattern.
Figure 3. (x3). USNM 739569; height 15.0 mm, diameter
6.5 mm.
Figure 4. Aspella hastula (Reeve). (x3). USNM 739567; height
12.4 mm, diameter 6.0 mm. Locality: Galapagos Islands, Ec-
uador.

Figure 5. Aspella pollux Radwin & D?’Attilio. (x3). USNM
739568; height 13.5 mm, diameter 7.0 mm. Locality: TU R-166,
Barra de Navidad, Jalisco, Mexico.

Figures 6, 7. Aspella strepta E. H. Vokes, spec. nov. Locality of
both: Azuero Peninsula, Panama.

Figure 6. (x4). USNM 838031 (holotype); height 11.5 mm,
diameter 3.3 mm.

Figure 7. (x4). USNM 838032 (paratype); height 11.2 mm,
diameter 5.0 mm. With intritacalx removed, showing under-
lying color pattern.
Figures 8, 9. Dermomurex (Gracilimurex) bakeri (Hertlein &
Strong). Locality of both: Manzanillo, Colima, Mexico.

Figure 8. (x3). Purdy Coll.; height 17.5 mm, diameter 8.5
mm.
Figure 9. (x4). Purdy Coll.; height 13.4 mm, diameter 5.5
mm. With intritacalx removed, showing underlying color pat-
tern.
Figure 10. Dermomurex (Gracilimurex) elizabethae (McGinty).
(x4). ANSP 176449 (holotype); height 12.5 mm, diameter 5.8
mm. Locality: Middle Sambo Shoals, Florida.
Figure 11. Dermomurex (Tnalatella) cunninghamae (Berry). (x3).
SUPTC 9502 (holotype); height 18.0 mm, diameter 9.2 mm.
Locality: Puerto San Carlos, Sonora, Mexico.
Figures 12, 13. Dermomurex (Trialalella) oxum Petuch.
Figure 12. (x3). USNM 780648 (holotype); height 12.5 mm,
diameter 6.6 mm. Locality: Abrolhos Archipelago, Bahia, Bra-
zil.
Figure 13. (x3). USNM 739571; height 9.0 mm, diameter
4.0 mm. Locality: TU R-98, Holandes Cay, off Cape San
Blas, Panama.
Figure 14. Dermomurex (Trialatella) abyssicola (Crosse). (* 3).
MHNP; height 10.1 mm, diameter 5.6 mm. Locality: Guade-
loupe. French Antilles.
Note: Except as indicated, all specimens whitened to show details
of ornamentation.

E. H. Vokes, 1985 Page 433

Page 434

pair of ridges immediately abapertural to these, the third
pair being reduced to buttresses across the suture. On fifth
postnuclear whorl an abrupt change of alignment, with
240° between one varix and the next formed; varical for-
mation thereafter only every 240°, creating a 60° offset
from each varix to the corresponding one on the previous
whorl, instead of being aligned up the spire as in the
earlier whorls; presence of former varical positions indi-
cated by buttresses across the suture. Except for the var-
ices, shell surface almost totally smooth and polished. Ap-
erture elongate-oval, inner lip appressed, unornamented;
inner side of outer lip with six small elongate denticles.
Siphonal canal short, dorsally recurved at distal end. Shell
covered with a thick intritacalx, marked only by a very
faint axial striae; when worn revealing a color pattern
consisting of a single brown band covering the area from
periphery to suture; apertural denticles tipped with brown.

Holotype: USNM 838031.

Dimensions of holotype: Height 11.5 mm, diameter 3.3
mm.

Type locality: Azuero Peninsula, Panama (approximate-
ly 7°15'N, 8°30'W), John Gunter Coll.

Paratype: USNM 838032; height 11.2 mm, diameter 5.0
mm; locality same as holotype.

Discussion: This new species seems very closely related
to Aspella pyramidalis, which also occurs in Panama. The
obvious difference is the peculiar offset in the later whorls,
giving rise to the twisted appearance of the shell indicated
by the species name (Greek—-streptos, twisted). The color
pattern, the nature of the intritacalx, and the form of the
aperture are all extremely close to A. pyramidalis. It is
unfortunate that none of the specimens in the type lot have
the protoconch preserved, for this might be a definitive
difference. At the present time, it is not inconceivable that
these specimens represent an atypical population of A.
pyramidalis but this seems unlikely.

The only other differences noted are that the spire of

The Veliger, Vol. 27, No. 4

Aspella strepta is higher and narrower than A. pyramidalis,
even in the early stages before the twisting occurs, and the
pronounced dorsoventral flattening is not as evident in the
new species. Also, the spiral lines seen in the intritacalx
of A. pyramidalis do not seem to be present in A. strepta.

The type lot consists of only three specimens, all col-
lected under stones at low tide by Mr. John Gunter, Pa-
nama City, Panama, and generously given to me for study.
No other specimens are known.

Genus Dermomurex Monterosato, 1890

Poweria MONTEROSATO, 1884:113. (Non Poweria Bona-
parte, 1840.)
Type-species: Murex scalarinus Bivona-Bernardi, by
original designation (Murex scalarinus Bivona-Ber-
nardi, 1832, =Murex scalaroides Blainville, 1829).
Dermomurex MONTEROSATO, 1890:181. New name for Pow-
erita Monterosato non Bonaparte.
Hexachorda COSSMANN, 1903:47.
Type-species: Murex tenellus Mayer, 1869, by original
designation.

Subgenus Dermomurex s.s.

Dermomurex (Dermomurex) obeliscus

(A. Adams, 1853)
(Figure 18)

Murex obeliscus A. ADAMS, 1853:269; SOWERBY, 1879:fig.
233.

Aspella (?Dermomurex) obeliscus (Adams): EMERSON &
D’ATTILIO, 1970:91, figs. 7-9 (figs. 8, 9, syntypes, Brit-
ish Museum); KEEN, 1971:527, fig. 1016.

Dermomurex obeliscus (Adams): D’ATTILIO & RADWIN, 1971:
346, figs. 1, 6 (intritacalx); RADWIN & D’ATTILIO, 1976:
46, pl. 1, figs. 21-24, text-fig. 23 (radula); Farr, 1976:
63, pl. 16, fig. 222.

Dermomurex (Dermomurex) obeliscus (Adams): VOKES, 1975:
NA

Discussion: First described without locality data, then
ascribed to the Caribbean by SOWERBY (1879:pl. 23, fig.

Explanation of Figures 15 to 21

Figures 15, 16. Dermomurex (Dermomurex) gunteri E. H. Vokes,
spec. nov. Locality of both: Los Buzos, Combutal, Azuero Pen-
insula, Panama.

Figure 15. (x3). USNM 838035 (holotype); height 20.0 mm,

diameter 8.4 mm.

Figure 16. (x3). USNM 838036 (paratype); height 15.3 mm,
diameter 7.0 mm.

Figure 17. Dermomurex (Takia) myrakeenae (Emerson & D’At-
tilio). (*3). Wright Coll. M-309; height 16.3 mm, diameter 9.0
mm. Locality: West Mexico.

Figure 18. Dermomurex (Dermomurex) obeliscus (A. Adams).

(x2%). USNM 838038; height 23.5 mm, diameter 11.0 mm.
Locality: Isla Islote, Nayarit, Mexico.

Figure 19. Dermomurex (Dermomurex) pauperculus (C. B.
Adams). (x2). MCZ 125072; height 30.0 mm, diameter 14.8
mm. Locality: Causeway, Biscayne Bay, Miami, Florida.
Figure 20. Dermomurex (Dermomurex) indentatus (Carpenter).
(x2). Gunter Coll.; height 29.0 mm, diameter 13.6 mm. Local-
ity: Montijo Bay, Panama.

Figure 21. Dermomurex (Dermomurex) alabastrum (A. Adams).
(x2). AMNH 186115; height 29.0 mm, diameter 13.0 mm.
Locality: St. Croix, Virgin Islands.

Note: All specimens whitened to show details of ornamentation.

E. H. Vokes, 1985 Page 435
SNE | Page 435

Page 436

233), it was not until 1970 that EMERSON & D’ATTILIO
(1970:91) demonstrated that this species is a member of
the west American fauna. The shell usually cited as “Mu-
rex obeliscus” from the Caribbean is Dermomurex pauper-
culus (C. B. Adams), which is indeed the Atlantic cognate
of D. obeliscus (see Figure 19), but it is not the same
species.

This is the most common of the west coast species of
Dermomurex, being found under stones at low tide, from
Mazatlan to Panama.

Dermomurex (Dermomurex) indentatus

(Carpenter, 1857)
(Figure 20)

Muricidea (?)erinaceoides var. indentata CARPENTER, 1857:
527.

Aspella (Dermomurex) perplexa KEEN, 1958a:248, pl. 30, fig.
11 (only).

Aspella (?Dermomurex) indentata (Carpenter): KEEN, 1958b:
365, fig. 378 (with A. perplexa in synonymy).

Muricidea (?)erinaceoides var. indentata Carpenter: KEEN,
1968:425, pl. 58, fig. 64 (holotype, British Museum).

Aspella (?Dermomurex) indentata (Carpenter): EMERSON &
D’ATTILIO, 1970:90, fig. 3.

Aspella (Dermomurex) indentata (Carpenter): KEEN, 1971:
527, fig. 1014 (left fig. = holotype A. perplexa Keen;
right fig. = holotype ““M.” indentata).

Dermomurex (Dermomurex) indentatus (Carpenter): VOKES,
1975:127.

Dermomurex indentatus (Carpenter): RADWIN & D’ATTILIO,
1976:46, pl. 1, fig. 17; Farr, 1976:50, pl. 16, fig. 218.

Discussion: Although described in 1857, this species was
not illustrated for one hundred years (KEEN, 1958b:fig.
378), and it was not until 1968 that a figure of the holo-
type was published (KEEN, 1968:pl. 58, fig. 64). In 1970
EMERSON & D’ATTILIO discussed “‘Aspella” indentata and
noted that it was “rare in collections.” This situation has
not changed; to my knowledge it is known only from Pa-
cific Panama and Sonora, Mexico, near the type locality,
Mazatlan (AMNH 180694).

The western Atlantic cognate of this species is the
equally poorly known Dermomurex alabastrum (A. Adams)
(see Figure 21), which I once suggested was probably a
synonym of D. indentatus (VOKES, 1975:140), as I had
never seen a specimen of the Atlantic species. This error
was corrected in a note on D. alabastrum (VOKES, 1976:
45), after having examined a number of the latter in the
collection of the late Mr. Gordon Nowell-Usticke of St.
Croix. One of his shells was figured at that time (VOKEs,
1976:text-fig. 1). The Nowell-Usticke collection is now in
the American Museum of Natural History.

Dermomurex (Dermomurex) gunteri
E. H. Vokes, spec. nov.

(Figures 15, 16)

Description: Shell elongate, with eight teleoconch whorls;
protoconch unknown (protoconch and several early whorls

The Veliger, Vol. 27, No. 4

usually truncated and plugged). On early postnuclear
whorls spiral ornamentation confined to a few faint spiral
threads, best seen with intritacalx partially worn away;
on median whorls gradually developing two, and then
three, wide flattened bands, each with a series of nodules
at regular intervals, approximately 0.5 mm apart; made
conspicuous by the intritacalx usually being worn from
the tops of the nodules, giving a dotted appearance to the
shell. On body whorl five such bands, becoming less dis-
tinct with adult growth; three spiral threads between each
pair of wider bands; that band at the base of the body
whorl (the one covered by successive whorls) much heavier
and less distinctly nodulose. Axial ornamentation on early
postnuclear whorls of six angulate ridges, each placed
abaperturally to corresponding varix on preceding whorl,
giving a backward spiral aspect to the varical line from
apex to canal. Varices initially narrow and flaring, six per
whorl until about sixth postnuclear whorl, then two of
every three gradually reduced in size, leaving a large,
flattened buttress across the suture to mark their former
position, as well as a slight flare along the siphonal canal;
the other two persisting, on opposite sides of the whorl,
as weak varices, only that at the aperture having any
strength at all. Suture impressed, divided by the varical
buttresses into a series of six deep pits per whorl. Aperture
large, oval; inner lip with a wide, thickened inductura,
free-standing and swept back over the parietal area at the
anterior portion, appressed at the posterior end; outer lip
with a rounded, sinuated edge, inner side patulous on
anterior half, with about six small denticles within. Si-
phonal canal short, broad, recurved distally; almost closed
but open by a narrow slit, with the two sides of the aper-
tural lips almost meeting across the opening, giving the
appearance of a circular parietal shield. Color of shell
basically a transparent white, but usually totally covered
by an extremely thick, cream-colored intritacalx; interior
of aperture enameled in a pale yellow, with the tips of
denticles touched by a small orange dot. Intritacalx when
fresh rather massive and unornamented, but when worn,
exhibiting a series of reticulated tunnels. Operculum and
radula unknown.

Holotype: USNM 838035.

Dimensions of holotype: Height 20.0 mm, diameter 8.4
mm.

Type locality: Los Buzos, Combutal, Azuero Peninsula,
Panama (approximately 7°15’N, 80°30’W), John Gunter
Coll.

Paratype: USNM 838036; height 15.3 mm, diameter 7.0
mm; locality same as holotype.

Discussion: During a visit to Panama I was given 16
specimens of a Dermomurex so totally different from all
described species there could be no question but that it
was new. Although its generic affinities are unmistakable,
there is no other living species with which it may be com-

E. H. Vokes, 1985

pared. The most conspicuous features include the large
flared aperture, in which the inductura is flattened so as
to look more like a Phyllocoma than a Dermomurex, and
the rows of nodules ornamenting the spiral bands. This
latter ornament is also seen in the French Miocene species
D. tenellus (Mayer) (figured in VOKES, 1975:pl. 2, figs. 1,
2), which is the only form that bears more than a generic
resemblance to D. gunterz. In the French species there is
also the tendency to develop only two varices on the adult
body whorl, but it lacks the flaring inductura and the very
deep pits along the sutural line. If D. tenellus is ancestral
to D. gunteri there should be some connecting forms
somewhere between the French Miocene and the Recent
eastern Pacific, but so far these have not been found.

The entire type lot was collected by John Gunter, of
Panama City, Panama. All were inhabited by hermit crabs
on a rocky shore. But it is evident from the fact that every
specimen has a damaged spire, which was plugged in life,
that the species lives in a relatively high energy environ-
ment, presumably among the same rocks, in the wave
zone.

Subgenus Gracilimurex Thiele, 1929

Gracilimurex THIELE, 1929:289.

Type-species: Murex bicolor Thiele, by original des-
ignation [Murex bicolor Thiele, 1929, non Murex
bicolor Risso, 1826, =Aspella baker: Hertlein &
Strong, 1951].

Dermomurex (Gracilimurex) bakeri
(Hertlein & Strong, 1951)

(Figures 8, 9)

Murex (Gracilimurex) bicolor THIELE, 1929:289, fig. 314 (non
M. bicolor Risso, 1826, nec Valenciennes, 1832, nec
Scacchi, 1833, nec Cantraine, 1835, nec Monterosato,
1878).

Aspella bakeri HERTLEIN & STRONG, 1951:79, pl. 26, figs.
1, 2; DUSHANE & SPHON, 1968:242, pl. 35, fig. 9 (ho-
lotype).

Aspella (?Aspella) baker: Hertlein & Strong: KEEN, 1958b:
364, fig. 375.

Gracilimurex bakeri (Hertlein & Strong): D’ATTILIO &
RADWIN, 1971:346, fig. 5 (intritacalx); Fair, 1976:23,
pl. 16, fig. 217.

Aspella (Gracilimurex) bakert Hertlein & Strong: KEEN, 1971:
529, fig. 1017.

Dermomurex (Gracilimurex) bakeri (Hertlein & Strong):
VOKES, 1975:129.

Dermomurex bakeri (Hertlein & Strong): RADWIN &
D’ATTILIO, 1976:45, pl. 1, figs. 18, 19.

Discussion: Dermomurex bakeri is a peculiar species, be-
cause of the tendency of the shell to have a bilateral flat-
tening similar to that in Aspella. However, the nature of
the ornamentation and the radula (unpublished drawing,
D’Attilio in litt.) seem to indicate placement in Dermo-
murex rather than Aspella. The only other closely related
form is the Atlantic cognate, D. (Gracilimurex) elizabethae

Page 437

(McGinty) (here figured, Figure 10), which (so far as is
known) is confined to Florida, the Bahamas, and Greater
Antilles, in the western Atlantic. Dermomurex bakeri is
equally limited in distribution, being known only from
the Gulf of California.

Subgenus 77ialatella Berry, 1964

Trialatella BERRY, 1964:149.
Type-species: Trialatella cunninghamae Berry, 1964, by
original designation.

Dermomurex (Trialatella) cunninghamae

(Berry, 1964)
(Figure 11)

Trialatella cunninghamae BERRY, 1964:149; Farr, 1976:35,
pl. 16, fig. 219 (holotype).

Aspella (Trialatella) cunninghamae (Berry): KEEN, 1971:529,
fig. 1019 (holotype).

Dermomurex (Trialatella) cunninghamae (Berry): VOKES,
1975:130, pl. 4, fig. 4 (holotype).

Dermomurex cunninghamae (Berry): RADWIN & D’ATTILIO,
1976:45, pl. 1, fig. 20 (paratype, Berry Coll.).

Discussion: Although named as the type of a new genus,
Trialatella, this species was placed in Dermomurex sub-
genus T7ialatella by VOKES (1975:130) as they differ only
by the expanded varices and the elongate siphonal canal.
At the same time, the Recent Caribbean “Murex” abys-
stcola Crosse, 1865, was placed in the same subgenus.
More recently PETUCH (1979:517, figs. 1-E, 1-F) has de-
scribed a second species from the western Atlantic, D.
(Trialatella) oxum, from the Abrolhos Archipelago, Brazil
(here figured, Figure 12).

Petuch did not compare his new species with Dermo-
murex abyssicola, simply stating that it was “the only At-
lantic Dermomurex” resembling the new form. There seems
little doubt that the specimen figured by VOKEs (1975:pl.
4, fig. 3; refigured here, Figure 13), as a possible juvenile
of D. abyssicola, is also to be referred to D. oxum. Crosse’s
type specimen cannot be located in either the Paris Mu-
séum d’Histoire Naturelle or the British Museum (Nat-
ural History), but J. P. Pointier, of the Paris Museum,
who has been studying the fauna of Guadeloupe for some
time (POINTIER et al., 1982) has collected numerous ex-
amples of a Dermomurex that we assume is D. abyssicola
(Figure 14), as this is the type locality for the species. He
has observed (personal communication) that the animal is
never associated with coral reefs, as PETUCH (1979) in-
dicated for D. oxum, but is found on the under side of
rocky ledges in about 5 m of water. However, Petuch
noted that the specimens of D. oxum were found dead in
the mud at the base of the reef, having rolled down after
death. This is almost certainly the explanation for the
extraordinary depth of 250 fathoms originally cited by
Crosse, for it is doubtful any member of the genus lives
at that depth.

Page 438

The Veliger, Vol. 27, No. 4

This may well be the explanation for the range of depths
recorded for the eastern Pacific Dermomurex cunning-
hamae, which is found in slightly deeper water than the
usual Dermomurex s.s., from 20 to 100 m. Records indi-
cate the form has been taken from off the coast of Mexico
(Sonora—the type and AMNH 186677; Nayarit—
AMNH 74162) and Pacific Panama (Isla Cebaco—
AMNH 213736; Isla Coiba—BMNH). The association
with rock rather than coral suggests that D. abyssicola is
the true cognate of D. cunninghamae rather than the coral-
associated D. oxum.

In addition to the still extant Dermomurex abyssicola
and D. oxum, there are several fossil species of 77zalatella
in the western Atlantic. The writer earlier (VOKES, 1975)
described D. farleyensis, from the early Miocene Chipola
Formation of northwestern Florida, and D. antecessor, from
the Pleistocene Moin and Bermont formations of Costa
Rica and Florida, respectively. In another paper (VOKES,
in press A) a fourth species is described from the Mio-
Pliocene Cercado/Gurabo Formation of the Dominican
Republic that seems to connect the younger and older
fossil forms. All of these are extremely similar to the east-
ern Pacific D. cunninghamae and it seems obvious the en-
tire group is very closely related.

Subgenus 7akia Kuroda, 1953

Takia Kuropa, 1953:190.
Type-species: Murex inermis Sowerby, 1841, by orig-
inal designation (non Murex inermis Philippi,
1836, nec M. inermis Dujardin, 1837 [? = Philip-
pi] = Dermomurex (Takia) infrons Vokes, 1974).

Dermomurex (Takia) myrakeenae

(Emerson & D’Attilio, 1970)
(Figure 17)

Aspella (Dermomurex) perplexa KEEN, 1958b:248, in part,
pl. 30, figs. 12, 13, only.

Aspella myrakeenae EMERSON & D’ATTILIO, 1970:89, figs.
1, 2, 4-6, 10 (operculum), 11 (radula).

Aspella (Dermomurex) myrakeenae Emerson & D?Attilio:
KEEN, 1971:527, fig. 1015 (holotype).

Dermomurex (Takia) myrakeenae (Emerson & D?Attilio):
VOKES, 1975:130, pl. 5, fig. 7.

Dermomurex myrakeenae (Emerson & D’Attilio): RADWIN
& D’ATTILIO, 1976:46, pl. 1, fig. 28.

Takia myrakeenae (Emerson & D?Attilio): Fair, 1976:61,
pl. 16, fig. 220.

Discussion: When the genus Dermomurex was treated by
VOKES (1975) it was noted that D. myrakeenae was most
closely related to the Indo-Pacific type of the subgenus
Takia. Only in the Oligocene do we find any other New
World species having an appearance much like that of the
eastern Pacific form. The Miocene species referred by
VOKES (1975:152-156) to the subgenus Viator (D. sex-
angulus, D. vaughani, D. curviductus, and D. taurinensis)
have been removed from the latter subgenus due to the
discovery of several Australian Tertiary species that change

ideas concerning evolution of the lineage (VOKES, in press
B). Although they are now considered better placed in
Takia they are probably not in a direct line from the
Oligocene D. cooke: Vokes to the Recent D. myrakeenae,
but represent another parallel lineage. However, in the
interval since 1975 there have been no other fossil species
discovered that shed any light on the connection between
the Oligocene and the Recent form.

This species is another of the relatively shallow-water
members of Dermomurex, being found in depths of from
3 to 20 m, only on the west coast of Mexico, from Cabo
San Lucas and Mazatlan, south to Acapulco.

ACKNOWLEDGMENTS

The writer is grateful to several persons for the loan of
specimens to figure. These are: Joseph Rosewater, U.S.
National Museum; Ruth Purdy, San Diego, California;
Eugenia Wright, Phoenix, Arizona; John Gunter, Pana-
ma City, Panama; and J. P. Pointier, Muséum National
d’Histoire Naturelle, Paris. In addition, a number of spec-
imens were originally photographed for the writer’s 1975
study and reused herein. For use of these, thanks are due
to the Harvard Museum of Comparative Zoology, Phila-
delphia Academy of Natural Sciences, California Acade-
my of Sciences, and American Museum of Natural His-
tory. Walter E. Sage III, of the latter institution, helpfully
supplied information on locality records of various species.
Myra Keen provided her usual superb editorial skill in
improving the manuscript. Finally, but most important of
all, the writer is especially appreciative of the gift of the
type material for the two new species described herein
from John Gunter, Panama City, Panama.

Supplementary Locality Data for Figured Specimens

The following are Tulane University Recent locality
numbers:

R-98. R/V Anton Bruun Cruise 10, dredged in 40 m,
northwest of Holandes Cay, and east-northeast of Cape
San Blas (9°37'N, 78°50'W), Panama.

R-166. Barra de Navidad, rocky point across inlet from
main sand bar, Jalisco, Mexico.

LITERATURE CITED

ApaMs, A. 1853. Descriptions of several new species of Murex,
Rissoina, Planaxis, and Eulima, from the Cumingian Collec-
tion. Proc. Zool. Soc. Lond. for 1851 (pt. 19):267-272.

Berry, S.S. 1964. Notices of new eastern Pacific Mollusca—
VI. Leaflets in Malacology 1(24):147-154.

BRoperip, W. J. 1833. Characters of new species of Mollusca
and Conchifera collected by Mr. Cuming. Proc. Comm. Sci.
Zool. Soc. Lond. for 1832 (pt. 2):173-179.

CARPENTER, P. P. 1857. Catalogue of the collection of Ma-
zatlan shells in the British Museum: collected by Frederick
Reigen. British Museum: London. i-iv + ix-xvi + 552 pp.

CossMANN, A. E. M. 1903. Essais de paledconchologie com-
parée. 5:215 pp., 9 pls.

E. H. Vokes, 1985

Page 439

D’AtTILIo, A. & G. E. RADwWIN. 1971. The intritacalx, an
undescribed shell layer in mollusks. Veliger 13:344-347, 1
pl., 1 text fig.

DUSHANE, H. & G. G. SPHON. 1968. A checklist of intertidal
mollusks for Bahia Willard and the southwestern portion
of Bahia San Luis Gonzaga, State of Baja California, Mex-
ico. Veliger 10:233-246, pl. 35.

EMERSON, W. K. & A. D’ATTILIO. 1970. Aspella myrakeenae,
new species from western Mexico. Nautilus 83:88-95, figs.
1-11.

Fair, R. 1976. The Murex book, an illustrated catalogue of
Recent Muricidae (Muricinae, Muricopsinae, Ocenebri-
nae). Privately printed: Honolulu, Hawaii. 138 pp., 23 pls.,
67 text figs.

HERTLEIN, L. G. & A. M. STRONG. 1939. Marine Pleistocene
Mollusks from the Galapagos Islands. Proc. Calif. Acad.
Sci. (4)23(24):367-380, pl. 32.

HERTLEIN, L. G. & A. M. STRONG. 1951. Descriptions of
three new species of marine gastropods from west Mexico
and Guatemala. Bull. So. Calif. Acad. Sci. 50(2):76-80.

HouartT, R. 1983. Three new tropical muricacean species
(Gastropoda:Muricidae). Venus 42: 26-33, pl. 1, text figs.
1-4.

KEEN, A. M. 1958a. New mollusks from tropical west Amer-
ica. Bull. Amer. Paleont. 38(172):239-255, pls. 30, 31.
KEEN, A. M. 1958b. Sea shells of tropical west America; ma-
rine mollusks from Lower California to Colombia. Stanford
Univ. Press: Stanford, Calif. xi + 624 pp., 10 color pls.,

1709 figs., 6 text figs.

KEEN, A. M. 1968. West American mollusk types at the Brit-
ish Museum (Natural History) IV. Carpenter’s Mazatlan
collection. Veliger 10:389-439, pls. 55-59, 171 text figs.

KEEN, A.M. 1971. Sea shells of tropical west America; marine
mollusks from Baja California to Peru. Second edition.
Stanford Univ. Press: Stanford, Calif. xiv + 1064 pp., 22
color pls., ca. 4000 figs., 6 maps.

KIENER, L. C. 1842. Spécies général et iconographie des co-
quilles vivantes 7, Famille des canaliféres, troisiéme partie,
Genre Ranelle. Paris. 40 pp., 15 pls.

Kuropa, T. 1953. On the Japanese species of 7rophon. Venus
17:186-202, text figs. 1-8.

KosuGE, S. 1984. Studies of the collection of Mr. Victor Dan
(6). Descriptions of new species of the genera Pterochelus,
Takia, Muricopsis and Cantharus. Bull. Inst. Malac. Tokyo
1(10):143-146, pls. 49, 50.

MonTErosaTo, T. A. 1884. Nomenclatura generica e specifica
de alcune Conchiglie Mediterranee. Palermo. 152 pp.

MonTerosatTo, T. A. 1890. Conchiglie della profundita del
mare di Palermo. Nat. Sicil. 9:181-191.

Morcu, O. A. L. 1877. Synopsis molluscorum minorum In-
diarum occidentalium imprimis insularum danicarum. Ma-
lak. Blatter 24:14-66.

Petucu, E. J. 1979. New gastropods from the Abrolhos Ar-
chipelago and reef complex, Brazil. Proc. Biol. Soc. Wash.
92:510-526, figs. 1-4.

POINTIER, J. P., J. M. ERAVILLE & A. DELPLANQUE. 1982.
Les coquillages de Guadeloupe. Xenophora (8):9-12; (9):
9-12; (10):12.

Rapwin, G. E. & A. D’ATTILIO. 1976. Murex shells of the
world, an illustrated guide to the Muricidae. Stanford Univ.
Press: Stanford, Calif. 284 pp., 32 pls., 192 text figs.

REEVE, L. A. 1844a. Monograph of the genus Ranella. In:
Conchologica iconica 2:8 pls.

REEVE, L. A. 1844b. Description of new species of Ranella.
Proc. Zool. Soc. Lond. for 1844 (pt. 12):136-140.

Sowersy, G. B. JR. 1835. Conchological illustrations, Ranella.
Pls. 84, 85, 88, 89, 92, 93.

Sowersy, G. B. JR. 1879. Thesaurus conchyliorum, 4 Murex:
1-55; 24 pls.

THIELE, J. 1929-1931. Handbuch der systematischen Weich-
tierkunde. 1:vi + 778 pp., 783 text figs. [Issued in parts, pp.
1-376 in 1929, fide Wenz, 1944—bibliography.]

Vokes, E. H. 1975. Cenozoic Muricidae of the western At-
lantic region. Part VI—Aspella and Dermomurex. Tulane
Stud. Geol. Paleont. 11:121-162, pls. 1-6, 2 tables, 1 text
fig.

VoKEs, E. H. 1976. Cenozoic Muricidae of the western At-
lantic region; Dermomurex—addendum. Tulane Stud. Geol.
Paleont. 12:45-46, 1 text fig.

Vokes, E. H. 1978. Muricidae (Mollusca:Gastropoda) from
the eastern coast of Africa. Ann. Natal. Mus. 23(2):375-
418, pls. 1-8.

Vokes, E. H. 1983. Update of Muricidae for “Sea Shells of
Tropical West America.” Western Soc. Malacol., Ann. Rept.
15:10-12.

Vokes, E. H. 1984. Comparison of the Muricidae of the east-
ern Pacific and western Atlantic, with cognate species. Shells
and Sea Life 16(11):210-215, 2 pls.

VoKES, E. H. In press A. Neogene Paleontology of the north-
western Dominican Republic; Part—Muricidae, Thaididae
(Mollusca: Gastropoda). Bull. Amer. Paleont.

VoKEs, E. H. In press B. The genus Dermomurex (Mollusca:
Gastropoda) in Australia. Malacol. Soc. Australia.

The Veliger 27(4):440-448 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

A Distributional List with Range Extensions of the
Opisthobranch Gastropods of Alaska

RICHARD S. LEE

University of Alaska, Juneau, Alaska 99801

NORA R. FOSTER

Aquatic Collection, University of Alaska Museum, Fairbanks, Alaska 99701

Abstract. The geographic occurrence of opisthobranch gastropods in the nearshore waters of Alaska
is documented. Scientific names, ranges, and new observations by the authors are presented for 82
species. Eleven records represent range extensions in the North Pacific.

INTRODUCTION

FEW STUDIES HAVE been done on opisthobranch gastro-
pods in Alaskan waters since the early work of DALL
(1871) and BERGH (1879, 1880). Sporadic collecting and
observations in southern Alaska have extended northward
and westward the known ranges of several species for-
merly listed for the California, Oregon, Washington, and
British Columbia coasts (ROBILLIARD, 1974; ROBILLIARD
& Barr, 1978; MILLEN, 1983). In the Arctic, MAc-
GINITIE (1959) noted the presence of several species near
Point Barrow. Two recent guides to the opisthobranchs
of the northeastern Pacific (MACDONALD & NYBAKKEN,
1980; BEHRENS, 1980) contain descriptions and color pho-
tographs of many of the species that may be found as far
north as Prince William Sound (61°N latitude) and as far
west as the Aleutian Islands. However, observations, col-
lections, and photographs by both of the present authors
have confirmed that for many species the northern and
western ranges are more extensive than previously noted.

This paper presents a summary of geographic distri-
bution data for the opisthobranch gastropods known to
inhabit the nearshore waters of Alaska. The listing of
families follows the order in which they are arranged in
KEEN & COAN (1974). Genera and species are in alpha-
betical order. Observations by Richard S. Lee are indi-
cated as (RSL); observations by Nora R. Foster, as (NRF);

specimens in the Aquatic Collection, University of Alaska ©

Museum, are indicated by (UAM). The 10 species that

are known only from the type specimens and original
descriptions are indicated by an asterisk (*); a dagger (T)
marks range extensions.

Order CEPHALASPIDEA
Family ACTEONIDAE

Rictaxis punctocaelatus (Carpenter, 1864)

Range: Ketchikan, Alaska to Magdalena Bay, Baja
California (DALL, 1921).

Alaskan records: Ketchikan (BEHRENS, 1980); south-
east Alaska—not specified (BAXTER, 1983).

Family ATYIDAE

Haminoea vesicula (Gould, 1885)

Range: Prince William Sound, Alaska to Magdalena
Bay, Gulf of California (BEHRENS, 1980).

Alaskan records: Ketchikan (BEHRENS, 1980); Drier
Bay, Prince William Sound (EYERDAM, 1924); Stephens
Passage; Zaikof Bay, Prince William Sound; Drier Bay,
Prince William Sound (UAM).

Remarks: 6 specimens from UAM were examined. Un-
common in grab samples nearshore from 30 to 50 m depth.

Haminoea virescens (Sowerby, 1833)

Range: Prince William Sound, Alaska (BEHRENS, 1980)
to Mazatlan, Baja California (Marcus, 1961).

Alaskan records: Alaska—not specified (BEHRENS,

R. S. Lee & N. R. Foster, 1985

Page 441

1980); Prince William Sound (R. Rosenthal, personal
communication).

Family RETUSIDAE

Retusa obtusa (Montagu, 1803)

Range: boreal Atlantic (THOMPSON & BRowN, 1976);
southern Bering Sea (KRAUSE, 1885).

Alaskan records: southern Bering Sea; near St. Law-
rence Island; (UAM) eastern Bering Sea (BAXTER, 1983);
St. Matthew Island (KRAUSE, 1885).

Remarks: 18 specimens from UAM were examined.
Common in grab samples from 30 to 100 m depth.

Retusa pertenuis Mighels, 1843
Range: Arctic Ocean; Bering Sea (KRAUSE, 1885);
Prince William Sound, Alaska (EYERDAM, 1924).
Alaskan records: Hinchinbrook Island, Prince William
Sound (EYERDAM, 1924); north of Akutan Pass, Aleutian
Islands (KRAUSE, 1885).

Retusa semen (Reeve, 1856)

Range: Arctic and North Atlantic—not specified (La
RocquE, 1953); Point Collinson, Alaska (DALL, 1919);
Prince William Sound, Alaska (EYERDAM, 1924).

Alaskan records: off Point Collinson (DALL, 1919);
Prince William Sound (EYERDAM, 1924).

Retusa umbilicata (Montagu, 1803)

Range: North Atlantic Arctic (MACGINITIE, 1959) to
Prince William Sound, Alaska (BAXTER, 1983).

Alaskan records: Prince William Sound (BAXTER, 1983);
R. cf. R. umbilicata, southern Bering Sea (UAM).

Remarks: 2 specimens from UAM were examined.

Family DIAPHANIDAE

Diaphana brunnea Dall, 1919

Range: Kodiak Island, Alaska (DALL, 1919) to Van-
couver Island and Strait of Georgia, British Columbia
(Cowan, 1964).

Alaskan records: Japonski Island (UAM); Kodiak Is-
land (type locality).

Remarks: 2 specimens from UAM were examined. Un-
common in the intertidal.

Diaphana minuta (Brown, 1827)

Range: Arctic and boreal Atlantic; Point Barrow, Alas-
ka (MacGINITIE, 1959) to the northwestern Gulf of Alas-
ka (BAXTER, 1983).

Alaskan records: Kenai Peninsula; Cook Inlet; north-
western Gulf of Alaska (BAXTER, 1983); Bering Sea
(LEMCHE, 1941); Point Barrow (MACGINITIE, 1959).

Family PHILINIDAE

Philine polaris (Aurivillius, 1885)

Range: Arctic seas to Nanaimo, British Columbia
(DALL, 1921).

Alaskan records: Prince William Sound to the Aleutian
Islands (BAXTER, 1983).

Philine sinuata Stimpson, 1850
Range: northwest Atlantic (LA ROCQUE, 1953); Port
Clarence, Bering Strait, Alaska (Krause in DALL, 1921).
Alaskan records: Port Clarence, Bering Strait (Krause
in DALL, 1921).

Family AGLAJIDAE

Aglaja ocelligera (Bergh, 1894)

Range: Cook Inlet, Alaska (BAXTER, 1983) to Santa
Barbara, California (BEHRENS, 1980).

Alaskan records: Kenai Peninsula; Cook Inlet (BAXTER,
1983); Sitka (type locality).

Melanochlamys diomedea (Bergh, 1894)

Range: Shumagin Islands, Alaska (BERGH, 1894) to
Newport Bay, California (BEHRENS, 1980).

Alaskan records: to Prince William Sound and the Ke-
nai Peninsula (BAXTER, 1983); Prince William Sound
(UAM); Kodiak Island; Shumagin Islands (BERGH, 1894).

Remarks: 5 specimens from UAM were examined. Un-
common in samples from mud or sandy intertidal habitats.

Family GASTROPTERIDAE

Gastropteron pacificum Bergh, 1894

Range: Unalaska Island, Alaska to San Diego, Cali-
fornia.

Alaskan records: lower Cook Inlet; Port Valdez (UAM);
Unalaska (type locality).

Remarks: 5 lots from UAM were examined.

Family SCAPHANDRIDAE

Acteocina oldroydi Dall, 1925

Range: Cook Inlet, Alaska (BAXTER, 1983) to British
Columbia (DALL, 1925).

Alaskan records: Olsen Bay, Prince William Sound;
Orca Inlet, Prince William Sound; Port Valdez (UAM);
Kenai Peninsula and Cook Inlet (BAXTER, 1983).

Remarks: 5 specimens from UAM were examined.

Cylichna alba (Brown, 1827)

Range: circumboreal to Monterey, California (DALL,
1921).

Alaskan records: Turner Bay, Icy Strait; Prince Wil-
liam Sound; Bristol Bay; Norton Sound; near Point Bar-
row (UAM); north of Akutan Pass, Aleutian Islands
(KRAUSE, 1885).

Remarks: 31 specimens from UAM were examined.
Very common in samples from 7 to 150 m.

Cylichna attonsa Carpenter, 1865

Range: eastern Bering Sea (BAXTER, 1983) to Baja Cal-
ifornia (LA ROCQUE, 1953).

Alaskan records: Gulf of Alaska (UAM); Afognak Is-
land (EYERDAM, 1960); eastern Bering Sea (BAXTER,
1983).

Remarks: 1 specimen from UAM was examined.

Page 442

Cylichna occulta Mighels, 1841

Range: Arctic and northwest Atlantic (LEMCHE, 1941);
Pt. Barrow, Alaska (MACGINITIE, 1959) to Afognak Is-
land, Alaska (EYERDAM, 1960).

Alaskan records: near Cordova; Bering Sea; Simpson
Lagoon; Colville River Delta (UAM); Afognak Island
(EYERDAM, 1960).

Remarks: 7 specimens from UAM were examined.

Cylichnella culcitella Gould, 1853

Range: Kodiak Island, Alaska to San Ignacio La-
goon, Baja California (BEHRENS, 1980).

Alaskan records: Kodiak Island (EYERDAM, 1960);
Prince William Sound; Kenai Peninsula (BAXTER,
1983).

Cylichnella harpa Dall, 1871

Range: Kenai Peninsula and Cook Inlet, Alaska
(BAXTER, 1983) to San Geronimo Island, Baja California
(BEHRENS, 1980).

Alaskan records: Prince William Sound; Kenai Penin-
sula (BAXTER, 1983); C. cf. C. harpa, Bering Sea near St.
Lawrence Island (UAM).

Remarks: 2 specimens from UAM were examined.

*Scaphander willetti Dall, 1919
Known only from the type specimen collected at Forres-
ter Island, Alaska.

Order NOTOASPIDEA
Family PLEUROBRANCHIDAE

+Berthella denticulatus (MacFarland, 1966)

Range; Point Craven, Alaska to Point Pinos, Pacific
Grove, California (LAMBERT, 1976).

Alaskan records: Point Craven (RSL); Hole-in-the-
Wall, Prince of Wales Island (UAM); Baranof Island
(BARR & BARR, 1983).

Remarks: Range extension from Baranof Island (BARR
& Barr, 1983). Two specimens from UAM were exam-
ined, both from the shallow nearshore subtidal (3 m).
Specimens from Point Craven had external cyclopoid co-
pepod parasites tentatively identified as Anthessius obtu-
sispina Ho, 1983.

Berthella sideralis (Loven, 1847)

Range: Norwegian coast (Odhner, 1939 in Mac-
FARLAND, 1966) to Unalaska Island, Alaska (Bergh, 1898
in MACFARLAND, 1966).

Alaskan records: Unalaska Island, Aleutians (Bergh,
1898 7n MACFARLAND, 1966).

Order NUDIBRANCHIA

Family ALDISIDAE

Aldisa cooper: Robilliard & Baba, 1972
Range: Hogan Island, Alaska to Trinidad Head, Cal-
ifornia (MILLEN, 1983).

The Veliger, Vol. 27, No. 4

Alaskan records: Sam Sing Cove (RSL); Hogan Island
(MILLEN, 1983).
Remarks: observed in the intertidal.

Aldisa zetlandica (Alder & Hancock, 1855)

Range: North Atlantic; Pt. Barrow, Alaska (Mac-
GINITIE, 1959).

Alaskan records: Point Barrow (MACGINITIE, 1959).

Family ARCHIDORIDAE

Archidoris montereyensis (Cooper, 1863)

Range: Kachemak Bay, Alaska (ROSENTHAL & LEES,
1976) to San Diego, California (ROBILLIARD, 1974).

Alaskan records: Port Valdez (ROBILLIARD, 1974); Sit-
ka (BERGH, 1878); Seldovia (RSL); Kalinin Bay (RSL);
Spruce Island (NRF); Kachemak Bay (ROSENTHAL &
LEEs, 1976).

Remarks: common in the intertidal.

Archidoris odhnert (MacFarland, 1966)

Range: Kenai Peninsula, Alaska (ROBILLIARD & BARR,
1978) to Point Loma, San Diego County, California
(ROBILLIARD, 1974).

Alaskan records: Port Dick (ROBILLIARD & BARR,
1978); Auke Bay (ROBILLIARD, 1974); Humpy Cove, Res-
urrection Bay (NRF); Three Entrance Bay; Sam Sing
Cove (RSL).

Remarks: observed in the intertidal and shallow subtid-
al.

Family ROSTANGIDAE

tRostanga pulchra MacFarland, 1905

Range: Point Craven, Alaska to Bahia de los Angeles,
Gulf of California (LANCE, 1966); Chile (Marcus, 1961);
Argentina (Marcus & Marcus, 1966 in McDONALD,
1983).

Alaskan records: Three Entrance Bay; Sam Sing Cove;
Kalinin Bay; Point Craven (RSL); Big Branch Rock (R.
Rosenthal, personal communication).

Remarks: range extension from Dundas Island, British
Columbia (LAMBERT, 1976). Common in the intertidal.

Family CADLINIDAE

Cadlina luteomarginata MacFarland, 1966

Range: Lynn Canal, Alaska (ROBILLIARD & BarRR,
1978) to Punta San Eugenio, Baja California (LANCE,
1961).

Alaskan records: Point Therese, Point Lena, and Amal-
ga Harbor, Lynn Canal (ROBILLIARD & Barr, 1978);
Three Entrance Bay; Sam Sing Cove; Halibut Point
(RSL).

Remarks: common in the intertidal.

+Cadlina modesta MacFarland, 1966
Range: Point Lena, Alaska to La Jolla, California
(MACFARLAND, 1966).

R. S. Lee & N. R. Foster, 1985

Alaskan records: Three Entrance Bay; Point Craven;
Point Lena (RSL).

Remarks: range extension from Vancouver Island, Brit-
ish Columbia (ROBILLIARD, 1971).

Cadlina pacifica Bergh, 1879
Range: Captain’s Bay, Unalaska Island, Alaska to Coal
Harbor, Shumagin Islands, Alaska (BERGH, 1879).
Alaskan records: Captain’s Bay, Unalaska Island; Coal
Harbor, Shumagin Islands (BERGH, 1879).

Family DIscoDORIDAE

TAnisodoris lentiginosa Millen, 1983

Range: Kenai Peninsula, Alaska; Strait of Georgia,
British Columbia (MILLEN, 1983).

Alaskan records: Gulf of Alaska (59°21.2'N,
150°28.4’W) (UAM).

Remarks: range extension from Queen Charlotte Strait,
British Columbia (MILLEN, 1983). One specimen from
UAM was examined.

+Anisodoris nobilis (MacFarland, 1905)

Range: Kodiak Island, Alaska to Baja California (FAR-
MER & COLLIER, 1963).

Alaskan records: Annette Island; Kalinin Bay; Seldovia;
Women’s Bay, Kodiak Island (RSL); Washington Bay,
Kuiu Island (EYERDAM, 1977); Spruce Island (UAM).

Remarks: range extension from Kuiu Island (EYERDAM,
1977). Uncommon in the intertidal. One specimen from
UAM was examined.

Discodoris sandiegensis Cooper, 1863

Range: Unalaska Island, Alaska (BERGH, 1894) to Cabo
San Lucas, Baja California, Mexico (LANCE, 1961); Ja-
pan (BaBa, 1957).

Alaskan records: Sam Sing Cove; Kalinin Bay; Wom-
en’s Bay, Kodiak Island (RSL); Peratrovich Island
(UAM); Unalaska (BERGH, 1894); Naked Island, Prince
William Sound; Kachemak Bay (ROSENTHAL & LEES,
1976).

Remarks: 2 specimens from UAM were examined.
Common in the intertidal.

Family CALYCIDORIDIDAE

Calycidoris guentheri Abraham, 1876

Range: Arctic seas; Bering Strait, Alaska (ROGINSKAYA,
1972).

Alaskan records: Bering Strait (ROGINSKAYA, 1972) near
Wainwright; near Pingok Island; Harrison Bay (UAM).

Remarks: 6 lots from UAM were examined. Uncom-
mon in samples from 14 to 44 m.

Family POLYCERATIDAE

*Issena pacifica Iredale & O’Donoghue, 1923
Known only from the type specimen collected at Uni-
mak Island, Alaska.

Page 443

*Palio pallida Bergh, 1880
Known only from the type specimen collected at Kiska
Harbor, Alaska.

Family TRIOPHIDAE

Triopha catalinae (Cooper, 1863)

Range: Amchitka Island, Alaska (ROBILLIARD, 1974)
to El Tomatal, Baja California (BERTSCH & Rosas, 1984);
Japan (BaBa, 1957).

Alaskan records: Shumagin Islands (BERGH, 1880);
Stephens Passage (BARR & BARR, 1983); Port Walter,
Baranof Island; Amchitka Island (ROBILLIARD, 1974);
Point Craven; Three Entrance Bay (RSL); Sunny Cove,
Spruce Island (NRF); Bluff Point, Kachemak Bay; Prince
William Sound (ROSENTHAL & LEES, 1976).

Remarks: commonly observed in the intertidal and sub-

tidal (3 m).

Family ONCHIDORIDAE

*Acanthodoris caerulescens Bergh, 1880
Known only from the type specimen collected at the
north end of Nunivak Island, Alaska.

tAcanthodoris hudsoni MacFarland, 1905
Range: Three Entrance Bay, Alaska to Gaviota, Santa
Barbara County, California (LEE & BRropny, 1969).
Alaskan records: Three Entrance Bay (RSL).
Remarks: range extension from Porcher Island, British
Columbia (LAMBERT, 1976). Occasionally observed in the
intertidal.

tAcanthodoris nanaimoensis O’ Donoghue, 1921

Range: Halibut Point, Baranof Island, Alaska to Pu-
risima Point, Santa Barbara County, California (LEE &
BROPHY, 1969).

Alaskan records: Three Entrance Bay; Halibut Point
(RSL).

Remarks: range extension from Wales Island, British
Columbia (LAMBERT, 1975). Commonly observed in the
intertidal.

Two color forms have been photographed in Sitka
waters. The more common is light gray to white in body
color with yellow-tipped papillae. The other form is brown
to brownish gray with the yellow tips of the papillae
standing out in strong contrast (RSL).

Acanthodoris pilosa (Abildgaard, 1789)

Range: circumboreal; Kiska Island, Alaska (BERGH,
1880) to Morro Bay, San Luis Obispo County, California
(McDONALD, 1983). :

Alaskan records: Kiska Island; Unalaska Island; Yukon
Harbor, Shumagin Islands (BERGH, 1880); Uyak Bay,
Kodiak Island (UAM); Kenai Peninsula; Cook Inlet
(BAXTER, 1983); Zaikof Bay, Prince William Sound (Ro-
senthal, personal communication).

Remarks: 2 lots from UAM were examined.

Page 444

* Adalaria albopapillosa (Dall, 1871)
Known only from the type specimen collected at Sitka
Harbor, Alaska.

Adalaria pacifica Bergh, 1880

Range: Pribilof Islands, Alaska to Victoria, British Co-
lumbia (MILLEN, 1983).

Alaskan records: Bering Sea, northwest of the Pribilof
Islands (UAM).

Remarks: 2 lots from UAM were examined.

* Adalaria tschuktschica Krause, 1885
Known only from the type specimen collected at “Met-
shigme Bay,” Bering Sea.

* Adalaria virescens Bergh, 1880
Known only from the type specimen collected at Un-
alaska Island, Alaska.

* Akiodoris lutescens Bergh, 1880

Range: Aleutian Islands (BERGH, 1880).

Alaskan records: Nazan Bay, Atka Island; Kiska Har-
bor; Unalaska Island (BERGH, 1880).

Onchidoris bilamellata (Linnaeus, 1767)

Range: circumboreal; Hagemeister Island, Alaska
(THOMPSON & BROWN, 1976) to Morro Bay, San Luis
Obispo County, California (MCDONALD, 1970).

Alaskan records: Kiska Island, Aleutians (BERGH, 1894);
Hagemeister Island; Sandborn Harbor, Shumagin Islands
(BERGH, 1880); Spruce Island (NRF); Berners Bay; Ju-
neau; Kalinin Bay; Point Craven; Point Courverden
(RSL); Nikishka Beach, Kenai Peninsula (UAM); Ka-
chemak Bay (ROSENTHAL & LEES, 1976).

Remarks: 4 lots from UAM were examined. Very com-
mon in the upper intertidal.

Onchidoris hystricina (Bergh, 1880)
Range: south of Cabo Colonet, Baja California (FAR-
MER, 1967) to Kiska Island, Alaska (BERGH, 1880).
Alaskan records: Washington Bay (EYERDAM, 1979);
Kiska Island (BERGH, 1880); Three Entrance Bay (RSL).
Remarks: not common. Observed once in the intertidal.

Onchidoris varians (Bergh, 1878)
Range: Aleutian Islands, Alaska (BERGH, 1878);
Washington Bay, Kuiu Island, Alaska (EYERDAM, 1977).
Alaskan records: Kiska Island; Unalaska Island (BERGH,
1878); Washington Bay (EYERDAM, 1977).

Family CORAMBIDAE

+Corambe pacifica MacFarland & O’Donoghue, 1929
Range: Punta San Eugenio, Baja California (Mc-
LD, 1983) to Sitka, Alaska.
an records: Sam Sing Cove (RSL); Ataku Island
(R. hal, personal communication).
Remai range extension from Nanaimo, British Co-
ONALD, 1983).

lumbia (1

The Veliger, Vol. 27, No. 4

Family TETHYIDAE

Melibe leonina (Gould, 1852)

Range: Kodiak Island, Alaska (EYERDAM, 1960) to
Punta Abreojos, Baja California (LANCE, 1966).

Alaskan records: Dall Island (O’DONOGHUE, 1926);
Three Entrance Bay; Sam Sing Cove (RSL); Still Harbor,
Baranof Island (UAM); Neets Bay (BARR & Barr, 1983);
Kodiak Island (EYERDAM, 1960); Kenai Peninsula; Cook
Inlet (BAXTER, 1983); Port Gravina, Prince William Sound
(ROSENTHAL, 1977).

Remarks: 2 specimens from UAM were examined.
Common in the low intertidal and shallow subtidal.

Family DENDRONOTIDAE

Dendronotus albus MacFarland, 1966

Range: Kenai Peninsula, Alaska (ROBILLIARD & BARR,
1978) to Coronado Islands, Baja California (ROBILLIARD,
1970).

Alaskan records: Port Dick, Kenai Peninsula (ROBIL-
LIARD & Barr, 1978).

Dendronotus dalli Bergh, 1879

Range: circumboreal; Bering Strait, Alaska to Puget
Sound, Washington (ROBILLIARD, 1970).

Alaskan records: Bering Strait (BERGH, 1879); Bering
Sea and Unalaska Island (MACFARLAND, 1966); South
Shelter Island (ROBILLIARD, 1974); southeast Bering Sea
(UAM).

Remarks: 5 lots from UAM were examined. Common
in samples from 50 to 100 m. Observed in the intertidal
in southeast Alaska.

Dendronotus frondosus (Ascanius, 1774)

Range: Arctic seas (THOMPSON & BROWN, 1976); cir-
cumboreal; Point Barrow, Alaska to southern California
(ROBILLIARD, 1970).

Alaskan records: Point Barrow (MACGINITIE, 1959);
Port Moller (BERGH, 1879); Hagemeister Island
(MACFARLAND, 1966); St. Lawrence Island (KRAUSE,
1885); Kalinin Bay (RSL); Norton Sound, western Beau-
fort Sea; northeast Chukchi Sea (UAM).

Remarks: 10 lots from UAM were examined. Common
in samples from 50 to 100 m.

Dendronotus iris Cooper, 1863

Range: Unalaska Island, Alaska to Coronado Island,
Baja California (ROBILLIARD, 1970).

Alaskan records: frequent records from the subtidal
waters throughout the state (ROBILLIARD, 1970); off Un-
alaska Island (ROBILLIARD, 1970); Steamer Bay (BARR &
Barr, 1983).

Dendronotus robustus (Verrill, 1870)

Range: eastern Chukchi Sea; Beaufort Sea; Arctic and
North Atlantic oceans (ROBILLIARD, 1970).

Alaskan records: western Beaufort Sea (71°35.4'N,
153°40.1’W); eastern Chukchi Sea (71°35'N, 163°58’W;
71°05'N, 160°08'W).

R. S. Lee & N. R. Foster, 1985

Remarks: 3 lots from UAM were examined. Uncom-
mon in samples from 46 to 62 m.

Dendronotus rufus O’Donoghue, 1921

Range: Auke Bay, Alaska (ROBILLIARD, 1974) to Se-
attle, Washington (ROBILLIARD, 1970).

Alaskan records: Auke Bay (ROBILLIARD, 1974); Ste-
phens Passage (BARR & BaRR, 1983).

Family TRITONIIDAE

Tochuina tetraquetra (Pallas, 1788)

Range: Kuril Islands; Unalaska Island, Alaska (BERGH,
1884) to Catalina Island, California (ROBILLIARD, 1974).

Alaskan records: Unalaska Island (BERGH, 1884); Res-
urrection Bay; northeast Gulf of Alaska (UAM); Sam
Sing Cove; Kalinin Bay (RSL); Naked Island, Prince
William Sound (ROSENTHAL & LEEs, 1982).

Remarks: common in samples from the northeast Gulf
of Alaska. Observed in the subtidal to 10 m in southeast
Alaska.

Tritonia diomedea Bergh, 1894

Range: Shumagin Islands, Alaska (BERGH, 1894) to
Panama; Okhotsk Sea; Japan; Florida (McDONALD,
1983).

Alaskan records: Shumagin Islands (BERGH, 1894);
northeast Gulf of Alaska; Prince William Sound (UAM);
Sam Sing Cove (RSL).

Remarks: 17 lots from UAM were examined. Common
in samples from the northeast Gulf of Alaska. Observed
to 10 m in southeast Alaska.

Tritonia festiva (Stearns, 1873)

Range: Kachemak Bay, Alaska (ROSENTHAL & LEES,
1976) to Los Coronados Islands, Baja California (LANCE,
1961); Japan (McDONALD, 1983).

Alaskan records: Port Dick, Kenai Peninsula (ROBIL-
LIARD & BARR, 1978); Steamer Bay (BARR & BarRR, 1983);
Sam Sing Cove (RSL); Kachemak Bay (ROSENTHAL &
LEES, 1976); Danger Island, Prince William Sound (R.
Rosenthal, personal communication).

Remarks: commonly observed in the subtidal to 10 m.

Family ARMINIDAE

tArmina californica (Cooper, 1863)

Range: Kayak Island, Gulf of Alaska to Panama
(BERGH, 1894).

Alaskan records: near Kayak Island, Gulf of Alaska
(UAM); Ernest Sound (D. Kowalski, personal commu-
nication); Slocum Arm (BARR & BarR, 1983).

Remarks: range extension from Slocum Arm, Chicha-
gof Island (BARR & BARR, 1983). One UAM specimen
was examined. Uncommon in the subtidal.

Family ZEPHYRINIDAE

Antiopella barbarensis (Cooper, 1863)
Range: Klu Bay, Revillagigedo Island, Alaska (ROBIL-

Page 445

LIARD & Barr, 1978) to Baja California and the Gulf of
California (MCDONALD, 1983).
Alaskan records: Klu Bay (ROBILLIARD & BARR, 1978).

Family DIRONIDAE

+Dirona albolineata (Eliot, 1905)

Range: Kachemak Bay, Alaska to La Jolla, California
(LANCE, 1966).

Alaskan records: Quiet Harbor (BARR & BarR, 1983);
Three Entrance Bay; Sam Sing Cove (RSL); Bidarka
Point, Prince William Sound; Kachemak Bay (R. Rosen-
thal, personal communication).

Remarks: range extension from Quiet Harbor, Etolin
Island, Alaska (BARR & Barr, 1983). Common in the
intertidal near Sitka.

Three color phases exist, the most common being white
in background. The next most frequent is a grayish-pink;
and the third, a clear light brick-red to pink form (RSL).

Dirona aurantia Hurst, 1966

Range: King Island, Norton Sound, Alaska (RoBIL-
LIARD & BARR, 1978) to Puget Sound, Washington
(ROBILLIARD, 1974).

Alaskan records: King Island; Pribilof Island; Unimak
Pass (ROBILLIARD & Barr, 1978); Stikine Pass (BARR &
Barr, 1983); Point Therese; Port Valdez (ROBILLIARD,
1974); Women’s Bay; Point Craven (RSL); Kachemak
Bay (R. Rosenthal, personal communication).

Remarks: commonly observed in the intertidal and sub-
tidal.

Family CORYPHELLIDAE

Flabellina fusca (O’ Donoghue, 1921)

Range: Port Valdez, Alaska (ROBILLIARD, 1974) to Seal
Rocks State Park, Oregon (ROBILLIARD, 1974).

Alaskan records: Auke Bay; Point Therese; Port Valdez
(ROBILLIARD, 1974); Point Craven (RSL); Tenakee Inlet
(BARR & Barr, 1983).

Flabellina salmonacea (Couthouy, 1838)

Range: Arctic circumboreal (MACGINITIE, 1959); Point
Barrow, Alaska to Pender Harbor, British Columbia
(MILLEN, 1983).

Alaskan records: Point Barrow (MACGINITIE, 1959);
Bering Strait (LEMCHE, 1941).

*Flabellina subrosacea (Eschscholtz, 1831)
Known only from the type specimen collected near Sit-
ka.

Flabellina trilineata (O’ Donoghue, 1921)

Range: Lisianski Inlet, Alaska to Los Coronados Is-
lands, Baja California (MILLEN, 1983).

Alaskan records: Lisianski Inlet (MILLEN, 1983).

*Flabellina trophina (Bergh, 1894)
Known only from the type specimen collected at Port
Althorp.

Page 446

The Veliger, Vol. 27, No. 4

Flabellina verrucosa (Sars, 1829)

Range: circumboreal; Hogan Island, Alaska to San Juan
Islands, Washington; Japan; North Atlantic (MILLEN,
1983).

Alaskan records: Hogan Island (MILLEN, 1983).

Family CUTHONIDAE

Cuthona concinna (Alder & Hancock, 1843)

Range: Lisianski Inlet, Alaska to White Rock, British
Columbia; North Atlantic (MILLEN, 1983).

Alaskan records: Lisianski Inlet, Alaska (MILLEN,
1983).

Cuthona nana (Alder & Hancock, 1842)

Range: Britain; Scandinavia; Bering Sea (THOMPSON
& Brown, 1976).

Alaskan records: St. Lawrence Bay, Bering Sea
(KRAUSE, 1885).

Family FIONIDAE

Fiona pinnata (Eschscholtz, 1831)

Range: pelagic in northern temperate oceans (LANCE,
1961).

Alaskan records: Sitka (type locality).

Family AEOLIDIIDAE

Aeolidia papillosa (Linnaeus, 1761)

Range: cosmopolitan in the Northern Hemisphere
(McDOonaLp, 1983).

Alaskan records: Chignik Bay; Sanborn Harbor, Shu-
magin Islands (BERGH, 1879); Tutka Bay; Izembek La-
goon (UAM); Outer Point; Sam Sing Cove; Point Craven
(RSL); Kachemak Bay (ROSENTHAL & LEES, 1976);
Rowan Bay (BARR & BarR, 1983).

Remarks: 2 UAM lots were examined. Uncommonly
observed in the intertidal.

Family PHIDIANIDAE

+Phidiana crassicornis (Eschscholtz, 1831)

Range: Kodiak Island, Alaska to the Gulf of California
(LANCE, 1966).

Alaskan records: Rowan Bay (BARR & BarR, 1983);
Wrangell; Baranof Warm Springs Bay; Juneau; Seldovia;
Seward; Kodiak (RSL); Sitka (BERGH, 1879); Port Val-
dez; Resurrection Bay (UAM).

Remarks: range extension from Rowan Bay, Kuiu Is-
land, Alaska (BARR & BARR, 1983). Very commonly ob-
served in the intertidal and subtidal (9 m).

Order GYMNOPHILA
Family ONCHIDELLIDAE

Onchidella borealis Dall, 1871
Range: Aleutian Islands, Alaska to northern California
(Marcus, 1961).

Table 1
New distribution sites of opisthobranch gastropods in
Alaska.
Latitude Longitude
Location (N) (W)
Annette Island 55°09’ 131°28’
Ataku Island 56°49'45" 1352295
Baranof Warm Springs Bay Sis05s 134°47'
Berners Bay 58°43’ 135°00'
Bidarka Point, Prince William
Sound 60°49’ 146°37’
Big Branch Rock, Baranof
Island 56°16'48” 134°50'50”
Bluff Point, Kachemak Bay 59°40’ 151°41’
Colville River Delta 70°27' 150°07’
Cordova 60°33’ 145°45'
Danger Island, Prince William
Sound 59°55'30" 148°05’
Drier Bay, Knight Island 60°18/30” 147°52'30"
Ernest Sound 56°11’ 132°18'
Halibut Point, Baranof Island 57°06’ 135°24’
Hole-in-the-Wall, Prince of
Wales Island 56°16'10” 133°37’
Humpy Cove, Resurrection Bay 59°58’ 149°18’
Icy Strait 58°18’ 134°45’
Izembek Lagoon 55°20’ 162°48’
Japonski Island 57°03’ 135°22'
Juneau 58°18'15” 134°24'30”
Kalinin Bay 57°20' 135°47'
Kayak Island 59°56’ 144°23'
Kodiak 57°47'20" 152°47'10"
Naked Island 60°40’ 147°25'
Nikishka Beach 60°45’ 151°18’
Olsen Bay 60°43'20" 146°12'30"
Orca Inlet 60°31’ 145°52'
Outer Point 58°18'05” 134°41'15”
Peratrovich Island DON 133°06'
Pingok Island, Harrison Bay 70°31'10” 149°31'30"
Point Bridget 58°40'45” 134°59'20"
Point Courverden 58°11'25” 135°03'10”
Point Craven 57°28! 134°52’
Port Lena 58°23'45" 134°46'45”
Port Valdez 61°05’ 146°39’
Sam Sing Cove 56°59’ 1B 522i
Seldovia 5922 Gullsy 151°42'30”
Simpson Lagoon 70°30' 149°12'
Spruce Island SSD} 152°25’
Stephens Passage 57°13’ 133°39'
Still Harbor, Baranof Island 56°33'30" 135°02’30”
Three Entrance Bay 56°58'40" 135°22’40”
Ugaiushak Island 56°47' 156°51'
Uyak Bay 57°48’ 154°04'
Women’s Bay 57°43’ 152°31’
Wrangell 56°28’ 132°22'40”
Zaikof Bay, Montague Island 60°19" 146°58’

Alaskan records: Tutka Bay; Spruce Island; Ugaiushak
Island; Point Bridget (UAM); Pt. Craven (RSL); Kache-
mak Bay (ROSENTHAL & LEES, 1976).

Remarks: 8 UAM specimens were examined. Common
in the upper intertidal.

R. S. Lee & N. R. Foster, 1985

DISCUSSION

It should be noted that 11 of the listed species are known
only from the type specimens or original collections, some
collected over 100 years ago. This lack of information may
be because recent collections or recorded observations are
few, or because the species in question have very limited
ranges.

Major range extensions include species found farther
west, 7.e., Anisodoris nobilis, and species found farther north,
1.e., Armina californica. The apparent lack of two major
groups, the Sacoglossa and Aplysiomorpha, as well as
the low number of Anaspidea may, likewise, reflect either
a lack of collections or the absence of these orders from
the Alaskan fauna.

ACKNOWLEDGMENTS

Special thanks are due the following people: Sandra Mil-
len, for identification of several specimens; Richard J. Ro-
senthal, for permission to use his observations, and for
comments on a draft of the manuscript; Max Hoberg, for
specimens of Aglaja and Haminoea from Prince William
Sound; Kathy Frost and Lloyd Lowry, for many speci-
mens from the Bering, Beaufort, and Chukchi seas; Judy
McDonald Paul, for comments on a rough draft of the
manuscript; David Turcott; Mel Sieffert, Bill Davidson,
and their students at Sheldon Jackson College, Sitka, for
help in collecting specimens; and Vickie Ivester for typing
several drafts of the manuscript.

LITERATURE CITED

Baba, K. 1957. A revised list of the species of Opisthobranchia
from the northern part of Japan, with some additional de-
scriptions. J. Fac. Sci., Hokkaido University, ser. 6, Zoology
13:8-14.

Barr, L. & N. Barr. 1983. Under Alaskan seas. Alaska
Northwest Publishing: Anchorage, Alaska. i-xiv + 200 pp.

BAXTER, R. 1983. Mollusks of Alaska. Bethel, Alaska. i-xii
+ 69 + i-xvil pp. (15 May 1983).

BEHRENS, D. W. 1980. Pacific coast nudibranchs. A guide to
the opisthobranchs of the northeastern Pacific. Sea Chal-
lengers, Inc.: Los Osos, California. 122 pp., 162 pls., 5 figs.

BerGH, L. S. R. 1879-1880. On the nudibranchiate gastero-
pod Mollusca of the North Pacific Ocean, with special ref-
erence to those of Alaska. Proc. Acad. Natur. Sci. Phila.
Part I (1879) pp. 71-132, pls. 1-8. Part II (1880) pp. 40-
127, pls. 1-8.

BeERGH, L. S. R. 1894. Die Opisthobranchien. Reports on the
dredging operations off the west coast of Central America
to the Galapagos, to the west coast of Mexico, and in the
Gulf of California. XIII. Bull. Mus. Comp. Zool., Harvard
25(10):123-233, pls. 1-12.

BertscH, H. & L. A. Rosas. 1984. Range extensions of nu-
dibranchs along the Pacific coast of Baja California, Mexico.
Nautilus 98(1):9-11.

Cowan, I. M. 1964. New information on the distribution of
marine Mollusca on the coast of British Columbia. Veliger
7(2):108-109.

DaLL, W. H. 1871. Descriptions of sixty new forms of mol-
lusks from the west coast of North America and the North

Page 447

Pacific Ocean, with notes on others already described. Amer.
J. Conchol. 7(2):93-160, pls. 13-16.

DaLL, W. H. 1919. The Mollusca of the Arctic coast of Amer-
ica collected by the Canadian Arctic expedition west from
Bathurst Inlet with an appended report on a collection of
Pleistocene fossil Mollusca. Rept. Canadian Arctic Exped.
1913-1918, vol. 8, pt. A, pp. 1A-25A, pls. 1-3.

DaLL, W. H. 1921. Summary of the marine shell bearing
mollusks .... Bull. U.S. Natl. Mus. 112:217 pp., 22 pls.

Dal, W. H. 1925. A new Acteocina from British Columbia.
Nautilus 39(1):25-26.

EYERDAM, W. J. 1924. Marine shells of Drier Bay, Knight
Island, Prince William Sound, Alaska. Nautilus 38(1):22-
29}

EYERDAM, W. J. 1960. Mollusks and brachiopods from Afog-
nak and Sitkalidak Islands, Kodiak Group, Alaska. Nauti-
lus 74(2):41-46; 74(3):91-95.

EYERDAM, W. J. 1977. A collection of mollusks from Wash-
ington Bay, Alaska. Of Sea and Shore 8:109-110.

FARMER, W. M. 1967. Notes on the Opisthobranchia of Baja
California, Mexico, with range extensions—II. Veliger 9:
340-342.

FARMER, W. M. & C. L. COLLIER. 1963. Notes on the Opis-
thobranchia of Baja California, Mexico, with range exten-
sions. Veliger 6:62-63.

Ho, J.-S. 1983. A new species of copepod associated with
Pleurobranchaea californica (Gastropoda: Opisthobranchia),
with a discussion on Anthessius associated with notoaspidean
sea slugs. Veliger 25(4):393-398.

KEEN, A. M. & E. Coan. 1974. Marine molluscan genera of
western North America. An illustrated key. Stanford Univ.
Press: Stanford, California. 208 pp.

Krause, A. 1885. Ein Beitrag fiir Kenntiss der molluscan
Fauna des Beringsmeeres; Brachiopoda und Lamellibran-
chiata. Archiv fiir Naturgesch. 51:14-40, 256-302.

LAMBERT, P. 1976. Records and range extensions of some
northeastern Pacific opisthobranchs (Mollusca: Gastropo-
da). Can. J. Zool. 54:293-300.

LaAncE, J. R. 1961. A distributional list of southern California
opisthobranchs. Veliger 4:64-69.

LANCE, J. R. 1966. New distributional records of some north-
eastern Pacific Opisthobranchiata with descriptions of two
new species. Veliger 9:69-81.

La RocquE, A. 1953. Catalogue of the recent Mollusca of
Canada. Natl. Mus. Can. Bull. 129, pp. i-ix, 1-406.

Leg, R. S. & P. BRopHy. 1969. Additional bathymetric and
locality data for some opisthobranchs and an octopus from
Santa Barbara County, California. Veliger 12:220-221.

LEMCHE, H. 1941. The zoology of East Greenland, Gastro-
poda: Opisthobranchiata. Meddelelser om Gronland 121(7):
1-49.

McDonaLp, G. R. 1970. Range extensions for Acanthodoris
hudsoni MacFarland, 1905, and Onchidoris bilamellata (Lin-
naeus, 1767). Veliger 12:375.

McDonaLp, G. R. 1983. A review of the nudibranchs of the
California coast. Malacologia 24(1-2):114-276.

McDonaLp, G. R. & J. W. NyBAKKEN. 1980. Guide to the
nudibranchs of California. American Malacologists: Mel-
bourne, Florida. 72 pp., 112 pls., 36 figs.

MacFarLanD, F. M. 1966. Studies of opisthobranchiate mol-
lusks of the Pacific coast of North America. Mem. Calif.
Acad. Sci. 6:1-546, pls. 1-72.

MacGinitig, N. 1959. Marine Mollusca of Point Barrow,
Alaska. Proc. U.S. Natl. Mus. 109:59-208, pls. 1-27.
Marcus, E. 1961. Opisthobranch mollusks from California.

Veliger 3(suppl. 1):1-85, pls. 1-10.

Page 448

The Veliger, Vol. 27, No. 4

MILLEN, S. V. 1982. A new species of dorid nudibranch (Opis-
thobranchia: Mollusca) belonging to the genus Anzsodoris.
Can. J. Zool. 60(11):2694-2705.

MILLEN, S. V. 1983. Range extensions of opisthobranchs in
the northeastern Pacific. Veliger 25(4):383-385.

O’DonoGHuE, C. H. 1926. A list of the nudibranchiate Mol-
lusca from the Pacific Coast of North America, with notes
on their distribution. Trans. Royal Canadian Inst., Toronto
15:119-247.

ROBILLIARD, G. A. 1970. The systematics and some aspects of
the ecology of the genus Dendronotus (Gastropoda:Nudi-
branchia). Veliger 12(4):433-479.

RoBILLIARD, G. A. 1971. Range extensions of some northeast
Pacific nudibranchs (Mollusca: Gastropoda: Opisthobran-
chia) to Washington and British Columbia with notes on
their biology. Veliger 14:162-165.

ROBILLIARD, G. A. 1974. Range extensions of some north-
eastern Pacific nudibranch molluscs. Can. J. Zool. 52(8):
989-992.

RoBILLIARD, G. A. & L. BARR. 1978. Range extensions of

some nudibranchs in Alaskan waters. Can. J. Zool. 56(1):
152-153.

RocinskayA, I. S. 1972. Calycidoris guenther: (Gastropoda,
Nudibranchia). Taksonomiya i rasprostranenie. Zoologi-
cheskii Zhurnal 51:913-918.

ROSENTHAL, R. J. 1977. Sea otters and their subtidal habitats
in Prince William Sound. Prepared for U.S. Department of
the Interior, Fish and Wildlife Service. 127 pp.

ROSENTHAL, R. J. & D. C. LEEs. 1976. Marine plant com-
munity studies, Kachemak Bay, Alaska. Prepared for State
of Alaska, Department of Fish and Game. 288 pp.

ROSENTHAL, R. J. & D. C. Legs. 1982. Description of Prince
William Sound shoreline habitats associated with biological
communities. Dept. Comm., OMPA. 58 pp.

THOMPSON, T. E. 1971. Tritoniidae from the North American
Pacific coast. Veliger 13(4):333-338.

Tuompson, T. E. & G. H. Brown. 1976. British opistho-
branch molluscs. Synopses of the British fauna No. 8, Ac-
ademic Press. 203 pp., 105 figs., 1 color plate.

The Veliger 27(4):449-451 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

NOTES, INFORMATION & NEWS

California Malacozoological Society

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Page 450

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The Veliger, Vol. 27, No. 4

Sale of C.M.S. Publications

All back volumes still in print, both paper covered and
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Supplements available from C.MLS.

Supplement to Volume 3:

{Part 1: Opisthobranch Mollusks of California by Prof.
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Part 2: The Anaspidea of California by Prof. R. Bee-
man, and the Thecosomata and Gymnosomata of the
California Current by Prof. John A. McGowan]

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[The Biology of Acmaea by Prof. D. P. Abbott et ai.,

ed. |
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Coan]

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[The Panamic-Galapagan Epitoniidae by Mrs. Helen
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Succession of Some Sessile Marine Invertebrates in
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Notes, Information & News

Annual Meeting
American Malacological Union

The American Malacological Union will hold its annual
meeting on the campus of the University of Rhode Island
on July 29-August 3, 1985. Three special symposia are
planned: one on molluscan egg capsules, organized by Jan
Pechenik; a second on molluscan radulae, organized by
Bob Bullock and Carole Hickman; and a third on the
ecology of freshwater mollusks, organized by Eileen Joki-
nen.

The Boston Malacological Club is planning special
events in commemoration of its 75th anniversary. There
will also be contributed papers, a poster session, marine
and freshwater field trips, workshops, an auction to ben-
efit the AMU Symposium Endowment Fund, exhibits,
and commercial sales of items of interest to attendees, and
a New England clam bake. A program to honor junior
malacologists will open the meeting.

For further details write to Dr. M. R. Carriker, College
of Marine Studies, University of Delaware, Lewes, DE
19958 (302-645-4274).

Annual Meeting
Western Society of Malacologists

The annual meeting of the Western Society of Malacol-
ogists will be held from August 18-21, 1985, on the cam-
pus of the University of California, Santa Barbara. The
main emphasis will be the molluscan fauna of the eastern
Pacific, with sessions concerning land snails, paleontology,
and other topics. There will be a symposium on Hawaiian
mollusks chaired by Mrs. Beatrice Burch.

Anyone interested in pre-registration or a call for pa-

Page 451

pers please contact William D. Pitt, President WSM, 2444
38th Avenue, Sacramento, CA 95822 (916-428-3899, home
evenings).

Notes to Prospective Authors

The increasing use of computers to prepare manuscript
copy prompts the following notes. We request that the
right margin of submitted papers be prepared “ragged,”
that is, not justified. Although right-justified margins on
printed copy sometimes look “neater,” the irregular spac-
ing that results between words makes the reviewer’s, ed-
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Other reminders are (1) that three copies of everything
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ends.

Because the Veliger is an international journal, we oc-
casionally receive inquiries as to whether papers in lan-
guages other than English are acceptable. Our policy is
that manuscripts must be in English. In addition, authors
whose first language is other than English should seek the
assistance of a colleague who is fluent in English before
submitting a manuscript.

The Veliger 27(4):452 (April 1, 1985)

THE VELIGER
© CMS, Inc., 1985

BOOKS, PERIODICALS & PAMPHLETS

Intertidal Plants and Animals of the
Landels-Hill Big Creek Reserve

Ava FERGUSON (editor). 1984. Publication No. 14, En-_

vironmental Field Program, University of California, Santa
Cruz. 106 pp., index map, 5 figs. $8.00. Copies are avail-
able from the Environmental Field Program, 231 Kerr
Hall, University of California, Santa Cruz, Santa Cruz,
CA 95064 ($8.00 plus $2.00 postage and handling; checks
payable to the UC Regents).

The University of California Natural Reserve System
(NRS) has been built in a brief span of 20 years into the
finest academic natural reserve system in North America,
and perhaps the world. The system currently contains 26
reserves encompassing undisturbed samples of 106 of the
state’s diverse natural habitat types. The reserves function
as outdoor laboratories and classrooms for researchers,
students, and teachers from institutions throughout the
world.

Under a cluster system of management, different re-
serves are administered by different campuses within the
University. The system is still too young to have generated
published surveys of its reserves. This volume summarizes
a study conducted in 1981 at four sites along the 2.8 km
shoreline of the Landels-Hill Big Creek Reserve in Mon-
terey County on the Big Sur Coast.

The Landels-Hill Big Creek Reserve was acquired in
1977 and is one of seven reserves in the System containing
marine habitats. The only other reserve in the System for
which published faunal documentation is available is the
Bodega Marine Reserve in Sonoma County (Standing, J.
M., B. Browning & J. W. Speth. 1975. The natural re-
sources of Bodega Harbor. Calif. State Dept. Fish & Game
Coastal Wetlands Series No. 11, 181 pp., 13 pls., 7 ap-
pendices). The Bodega Marine Laboratory and research
interest in Bodega harbor predate the Reserve System, so
it is not surprising that the fauna is better known. How-

ever, even the Standing report is not well known or widely
distributed. It is for this reason that I have chosen to
preface this review with some background information on
the Natural Reserve System.

The Big Creek Reserve is important because it lies
within the poorly understood transition between the tem-
perate Oregonian Marine Province and the warm tem-
perate Californian Marine Province. In addition to its
biologically unexplored characteristics as a transition zone,
this segment of coast stands as a relatively remote and
isolated region between two of the most densely urbanized
and disturbed segments of the California Coast. Heavy
wave impact and exposures of greenstone (a substrate of
unusual properties) may help account for the relatively
simple intertidal communities, although they have a num-
ber of notable aspects, including one of the few undis-
turbed California mainland populations of the large owl
limpet, Lottia gigantea.

This volume documents, with annotated lists, 88 species
of algae, 2 marine vascular plants, and 192 species of
invertebrates (55 mollusks) and provides an excellent
overview of the intertidal zonation, the community ecol-
ogy, and the provincial affinities and unique features of
the marine flora and fauna.

What is most remarkable is that this volume is the
result of the work of an undergraduate biology class at
U.C. Santa Cruz, taught by David R. Lindberg, assisted
by Douglas J. Eernisse, and Chet Chaffee. It was assem-
bled from a combination of their efforts and compilation
and editing of student reports. The level of student con-
tribution is impressive, including some highly professional
drawings and spectacular photographs. The publication
will serve not only as an invaluable reference for future
research on this remote stretch of coastline in the transi-
tion zone, but it will provide a model for the conduct of
similar baseline studies.

C. S. Hickman

Information for Contributors

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review process, manuscripts, including figures, should be submitted in triplicate. The
first mention in the text of the scientific name of a species should be accompanied by the
taxonomic authority, including the year, if possible. Underline scientific names and other
words to be printed in italics. Metric and Celsius units are to be used.

The sequence of manuscript components should be as follows in most cases: title page,
abstract, introduction, materials and methods, results, discussion, acknowledgments, lit-
erature cited, figure legends, figures, footnotes, and tables. The title page should be on a
separate sheet and should include the title, author’s name, and address. The abstract
should describe in the briefest possible way (normally less than 200 words) the scope,
main results, and conclusions of the paper.

Literature cited

References in the text should be given by the name of the author(s) followed by the
date of publication: for one author (Smith, 1951), for two authors (Smith & Jones, 1952),
and for more than two (Smith et al., 1953).

The “literature cited” section must include all (but not additional) references quoted
in the text. References should be listed in alphabetical order and typed on sheets separate
from the text. Each citation must be complete and in the following form:

a) Periodicals
Cate, J. M. 1962. On the identifications of five Pacific Mitra. Veliger 4:132-134.

b) Books
Yonge, C. M. & T. E. Thompson. 1976. Living marine molluscs. Collins: London.
288 pp.

c) Composite works

Feder, H. M. 1980. Asteroidea: the sea stars. Pp. 117-135. In: R. H. Morris, D. P.
Abbott & E. C. Haderlie (eds.), Intertidal invertebrates of California. Stanford Univ.
Press: Stanford, Calif.

Tables
‘Tables must be numbered and each typed on a separate sheet. Each table should be
headed by a brief legend.

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Text figures should be in black ink and completely lettered. Keep in mind page format
and column size when designing figures.

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and that lettering size is appropriate to the figure. Charges will be made for necessary
alterations.

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Upon receipt each manuscript is critically evaluated by at least two referees. Based on
these evaluations the editor decides on acceptance or rejection. Acceptable manuscripts
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be charged to the author at cost. One set of corrected proofs should be returned to the
editor.

An order form for the purchase of reprints will accompany proofs. If reprints are
desired, they are to be ordered directly from the printer.

Send manuscripts, proofs, and correspondence regarding editorial matters to: Dr. David W.

Phillips, Editor, 2410 Oakenshield Road, Davis, CA 95616 USA.

CONTENTS — Continued

Patelloida chamorrorum spec. nov.: a new member of the Tethyan Patelloida
profunda group (Gastropoda: Acmaeidae).
Davip R. LINDBERG AND GEERAT J. VERMEIJ

A new species of Cuthona from the Gulf of California.
DAVIDIW ) BEHRENS] iea bist see bedn 2 fuego rari ele ee

Three new species of Lepidozona (Mollusca: Polyplacophora) from the Gulf of
California.
ANTONIO: J PERRIEIRAS (2 (00654 20h ga ka a C0 geist ue

Review of the west coast aspelloids Aspella and Dermomurex (Gastropoda: Mu-
ricidae), with the descriptions of two new species.
EMILy H. VOKEs

A distributional list with range extensions of the opisthobranch gastropods of
Alaska.
RICHARD S. LEE AND Nora R. FOSTER

NOTES, INFORMATION & NEWS

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