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Full text of "Transactions of the San Diego Society of Natural History"



HARVARD UNIVERSITY 

Library of the 

Museum of 

Comparative Zoology 






TRANSACTIONS 
OF THE 

SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOLUME 16 

1970-1972 



Printed from the 
W. W. Whitney Publication Endowment 



COMMITTEE ON PUBLICATION 

CARL L. HUBBS 

JOSEPH R. JEHL, JR. 

ARNOLD ROSS 



CONTENTS 



1. Studies on the Tetraclitidae (Cirripedia: Thoracica) : a proposed new 
genus for the Austral species TetracUta purpurascens breviscutiim. By 
Arnold Ross. 24 February 1970 1-12 

2. The shallow water anomuran crab fauna of southwestern Baja California, 
Mexico. By Janet Haig. Thomas S. Hopkins and Thomas B. Scanland. 

4 June 1970 13-32 

3. Comparative biology of American black widow spiders. By B. J. Kaston. 

24 July 1970 33-82 

4. Eastern Pacific Crown-of-Thorns starfish populations in the lower Gulf 

of California. By Thomas Dana and Arthur Wolfson. 24 November 1970 83-90 

5. Evolution of Peromyscus on northern islands in the Gulf of California, 
Mexico. By Timothy E. Lawlor. 24 February 1971 91-124 

6. Lampeira (Eiitosphemis) lethophaga, new species, the nonparasitic deriva- 
tive of the Pacific lamprey. By Carl L. Hubbs. 30 April 1971 125-164 

7. Recent ostracodes from Clipperton Island, eastern tropical Pacific. By 

Edwin C. Allison and John C. Holden. 14 May 1971 165-214 

8. Studies on the Tetraclitidae (Cirripedia: Thoracica): a new tetraclitellan 

from India. By Arnold Ross. 21 May 1971 215-224 

9. Stratigraphy of the Poway area, southwestern California. By Gary L. Peter- 
son. 9 July 1971 225-236 

10. Herpetofauna of the Pacific coast of north central Baja Cahfornia, Mexico, 
with a description of a new subspecies of Phyllodactylus xanti. By Dennis 

L. Bostic. 25 August 1971 237-264 

11. A new genus of Chthamalidae (Cirripedia) from the southeastern Pacific 

island of San Ambrosio. By Arnold Ross. 26 October 1971 265-278 

1 2. The larval and pupal stages of four species of Cafius (Coleoptera: Staphy- 
linidae) with notes on their biology and ecology. By Gary J. James, Ian 

Moore and E. F. Legner. 5 November 1971 279-290 

13. The color patterns of downy young ratites and tinamous. By Joseph R. 

Jehl, Jr. 15 November 1971 291-302 

14. Cenozoic calcareous nannofossils from the Pacific Ocean. By David Bukry. 

7 December 1971 303-328 

15. An upper Pleistocene marine fauna from Mission Bay, San Diego, Cali- 
fornia. By J. Philip Kern, Tom E. Stump and Robert J. Dowlen. 29 De- 
cember 1971 329-338 

16. The systematic position of Urosalpinx carolinensis Verrill, 1884 with com- 
ments on the genus Mohnia Friele, 1878. By George E. Radwin. 12 Janu- 
ary 1972 339-342 



n ^ 




MUS. COMP. ZOOL. 
LIBRARY 

MAR 1 1970 

HARVARD 
UNIVERSITY 



STUDIES ON THE TETRACLITIDAE 
(CIRRIPEDIA: THORACICA): A PROPOSED 
NEW GENUS FOR THE AUSTRAL SPECIES 
TETRACLITA PURPURASCENS BREVISCUTUM 



ARNOLD ROSS 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



VOL. 16, NO. 1 24 FEBRUARY 1970 



STUDIES ON THE TETRACLITIDAE 
(CIRRIPEDIA: THORACICA): A PROPOSED 
NEW GENUS FOR THE AUSTRAL SPECIES 
TETRACLITA PVRPVRASCENS BREVISCUTUM 

ARNOLD ROSS 



ABSTRACT. - Epopella gen. nov. is proposed for the Auckland Islands species Tetraclita purpurascens 
forma breviscutum Broch, 1922, a solid-walled tesseroporan. Elminius plicatus Gray and E. simplex Darwin 
are assigned provisionally to this new genus on the basis of morphological similarities. Epopella. containing 
the most primitive tetraclitids, is inferred to have evolved during the early Paleogene, and it is from this 
group that Tesseropora and later tesseroporans are derived. 

RESUMEN. — Epopella gen. nov. esta propuesto para el especies de las Islas Auckland Tetraclita 
purpurascens forma breviscutum Broch, 1922, un tesseroporan que tiene una pared soVida. Elminius plicatus 
Gray y E. simplex Darwin son asignados provisionalmente a este genero nuevo en el base de semejanzas 
morfologicas. Epopella. conteniendo las tetraclitids mas primitivas se infiera que ha evolucionada durante 
del Paleogena, y es de este groupo que Tesseropora y tesseroporans mas tarde estan derivado. 



Knowledge of the tetraclitid fauna of Australia, Tasmania, New Zealand, and the 
islands comprising the Antipodean Province is limited. Aside from the taxon Broch (1922: 
337) described as Tetraclita purpurascens forma breviscutum. the following species are 
known from this region: Tesseropora rosea (Darwin, 1854: 335; Linzey, 1942: 280; Pope, 
1945: 366; Wisely and Blick, 1964: 166), Tetraclita vitiata (Stephenson, 1968: 51), and 
Tetraclitella purpurascens (Darwin, 1854: 337; Linzey, 1942: 279; Foster, 1967a: 83; 
1967b: 35). 

Tetraclita purpurascens forma breviscutum was collected by the Th. Mortensen 
Pacific Expedition (1914-1916) on Auckland Island, the largest of several islands in the 
Auckland Islands Group (Fig. 1 ), and more recently it has been found on Rose Island. This 
species has neither been reported nor found in collections from any other locality and 
appears to be endemic to the Auckland Islands. Unfortunately, there is little known about 
the ecology of this tetraclitid. 

Hiro (1939: 275) noted differences in the opercular plates of T. purpurascens forma 
breviscutum that indicated it was not closely related to the nominate subspecies. However, 
he failed to indicate the affinities of this form to other tetraclitid groups. In re-examining 
the type specimens I noted several salient wall structures that readily characterize this 
taxon at the generic and specific level and suggest that its affinities are to the tesseroporan 
rather than to the tetraclitellan lineage (Ross, 1969: 238). Consequently, the ''forma" 
breviscutum is elevated to specific rank and the genus Epopella proposed for it and two 
other related species. 

FAMILY TETRACLITIDAE Gruvel 

Remarks. — The familial diagnosis presented earlier (Ross, 1969: 238) is emended to 
include those species that lack an inner lamina and have an outer lamina permeated by 
cuticular chitin. 

SAN DIEGO SOC. NAT. HIST., TRANS. 16(1): 1-12, 24 FEBRUARY 1970 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



166°10' E 



ROSE ISLAND 

j ^---v- ENDERBY ISLAND 

O SARAH'S BOSOM 

HARBOR 



12 3 4 5 



50°40'S- 




Figure 1. Map of Auckland Islands Ciroup, and its position relative to New Zealand (inset). The known 
occurrences oi Epopella breviscutum are Sarah's Bosom Harbor and Rose Island. 



1970 ROSS: STUDIES ON THE TETRACLITIDAE 3 

KEY TO GENERA OF THE TESSEROPORAN GROUP 

1 . Parietal tubes uniformly distributed in one row 2 

1 . Parietal tubes uniformly distributed in more than two rows, or lacking 3 

2. Parietal tubes bearing transverse septa; scutum lacking depressor 

muscle crests (1 sp., eastern Pacific, Pliocene) Tesseroplax 

2. Parietal tubes lacking transverse septa; scutum bearing depressor muscle 
crests (5 spp., Indo-West Pacific, Recent; Italy, Oligocene) Tesseropora 

3. Inner lamina present; longitudinal septa continuous; sheath adpressed, 
basal margin not depending (19 spp., tropical, warm temperate, 
cosmopolitan. Pliocene to Recent) Tetraclita 

3. Inner lamina absent; longitudinal septa discontinuous; sheath free 

with basal margin depending (3 spp., southeast Australia, New Zealand, 
Recent) Epopella 

Epopella gen. nov. 

Definition. — Shell large, conic; compartments may or may not be discrete; parietes 
effectively solid, permeated with cuticular chitin, and commonly discontinuous plates or 
longitudinal lamina depend from inner surface; radii non-tubiferous, narrow or obsolete; 
basis membranous; scutum triangular, higher than wide, bearing crests for depressor 
muscles; tergum narrow, spur not well separated from basi-scutal angle, truncate basally; 
mandible with 4 teeth, basal comb, and spine-like inferior angle; maxilla I with 10-16 spines 
comprising medial cluster of cutting edge. 

Type species. — Tetraclita (Tetraclita) purpurascens forma breviscutum Broch, 1922, 
Recent, Auckland Island. 

Etymology. — Named in honor of Elizabeth C. Pope, the Australian Museum, in 
recognition of her many contributions to the Cirripedia of the Australian region. 

Epopella breviscutum (Broch) 

Tetraclita (Tetraclita) purpurascens forma breviscutum Broch, 1922: 337, figs. 71, 72. 
Tetraclita ( Tetraclitella ) purpurascens forma, breviscutum: Hiro, 1939: 275. 

Material. — Rose Island, Auckland Islands; intertidal; J. C. Yaldwyn, coll., January, 
1963; 2 dried specimens lacking appendages and body; in collections of Dominion 
Museum, Wellington, New Zealand. 

Sarah's Bosom Harbor (Port Ross), Auckland Island, Auckland Islands; under stones 
at low tide; Th. Mortensen Pacific Expedition, November 26, 1914; 5 complete specimens; 
in collections of Universitetets Zoologiske Museum, Copenhagen, Denmark. 

Supplementary Description. — Shell low, conic; grayish-white; parietes deeply 
eroded; growth ridges discernible along basal margin only; orifice pentagonal with 
peritreme eroded; radii extremely narrow or obsolete, with articular surfaces weakly 
crenate; compartments weakly articulated when not secondarily fused; no inner lamina; 
longitudinal septa discontinuous basally, not fused, forming separate, smooth, depending 
plates (Fig. 2d), in general appearance not much unlike that of Chelonobia testudinaria; 
basal margin of sheath free, depending (Fig. 2d). Basis membranous. Measurements (in 
mm.) of the lectotype (26-XI-14D), paralectotypes (26-XI-A-C,E), and specimens from 
Rose Island (spec. F, G) are presented in Table 1 . 

External surface of opercular plates deeply eroded (Fig. 2a, b). Scutum triangular, 
commonly slightly higher than wide, articular ridge sinuous, about 2/3 length of tergal 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



K^ 




'^l^'^- 






; \ 



\ 



V^ 



Figure 2. Shell and opercular plates of Epopella brevisculum. a, external view of scutum; b, external view of 
tergum; c, internal view of tergum; d, basal view of shell; e, internal view of scutum. Lectotype (26-XI-14D), a-c, 
e; paraleclotype (26-XI-14A), d. 



margin; adductor ridge erect, undercut, fused apically with articular ridge and extending 
nearly to basal margin; adductor muscle depression ovate, deep; 3-4 crests for rostral 



1970 



ROSS: STUDIES ON THE TETRACLITIDAE 



depressor muscle, low, thin, partially hidden by infolding of occludent margin; 4-5 crests 
for lateral depressor muscle, high, broad, clearly exposed; overall surface of plate pitted 
(Fig. 2e). 

Tergum higher than wide, apically eroded; external longitudinal furrow open, shallow, 
extending to base of spur; spur truncate basally, width more than 1/2 that of basal margin; 
articular ridge erect or inclined, undercut along basal portion; articular furrow broad and 
deep; 5-7 crests for depressor muscles, short, broad, erect, bearing close-spaced, thin, 
lateral extensions (Fig. 2c). 

Table 1. Measurements of Individual Specimens 



Specimen 

Auckland Id. 

26-XI-14A 

26-XI-14B 

26-XI-14C 

26-XI-14 D(lectotype) 

26-XI-14E 

Rose Id. 

F 
G 





Shell 






Opercu 


lar Plates 




C-RDia. 


Width 


Height 


S. H. 


S. W. 


T. H. 


T. W 


29.9 


29.2 


14.4 


9.4 


8.7 


8.3 


5.1 


31.1 


26.9 


12.2 


8.3 


9.1 


8.1 


5.3 


31.0 


30.9 


14.3 


10.1 


9.4 


8.7 


4.9 


28.7 


25.9 


14.8 


9.1 


9.2 


8.4 


5.1 


32.9 


31.4 


12.7 


8.2 


10.2 


8.9 


5.2 


16.8 


19.4 


9.4 


7.8 


7.2 


6.4 


4.8 


16.1 


18.5 


10.8 


6.8 


6.5 


5.1 


4.8 



Crest of labrum thick, heavily chitinized, with shallow medial notch (Fig. 30; 
multidenticulate, 22-39 simple teeth along crest and in notch (Fig. 3g); short soft setae 
along crest and commonly between the teeth. 

Palps bluntly rounded distally; superior margin concave, basal convex; distal setae 
1/2 longer than superior; both bipinnate. 

Mandible with 5 teeth including inferior angle (Fig. 3a); teeth 2-4 with subsidiary 
cusps; superior slope of tooth 4 smooth; inferior angle coarsely serrate, 28-42 overlapping, 
narrowly triangular teeth. 

Maxilla I deeply notched subapically (Fig. 3c); spines along cutting edge in 3 clusters; 
2 long, stout and 4-6 short, slender spines above notch; 10-16 long or short slender spines 
medially; 7-15 very short and slender spines basally. 

Maxilla II taller than broad (Fig. 3e); anterior margin bilobate; basal lobe covered 
with cluster of pustules along anterior border. 

Rami of cirrus I grossly unequal in length (Fig. 4a); posterior ramus about 1/2 length 
of anterior ramus. Rami of cirrus II either essentially equal in length or inner ramus 
slightly shorter; intermediate articles of both rami squat, slightly protuberant; setae on 
both rami coarsely bipinnate, not comb-like. Rami of cirrus III antenniform (Fig. 4d); 
outer ramus approximately 3/5 length of inner ramus; basal segments of both rami armed 
with comb-setae lacking basal guards (Fig. 4e). Cirri IV-VI essentially equal in length with 
equal rami; 3-5 short, slender setae at each articulation along greater curvature of 
intermediate articles; a single row of ctenae occurs along lateral face immediately below 
articulation; commonly 4 pairs of setae on cirri IV-V, and 3 on cirrus VI (Fig. 40: at base 
of and between each major pair of setae is a cluster of 4-9 long bristles. Cirral counts for 
the specimens in the type lot are summarized in Figure 5. 

Intromittent organ annulated throughout its length, and sparsely covered with short 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 








bf 05mm 

a 25mm 

9 1mm 

25mm 

5mm 



cd 



■—^^UMvtaL 



'>^^^ 




Figure 3. Trophi of Epopella breviscutum. a, mandible; b, enlarged view of inferior angle of mandible in fig. a; c, 
maxilla I; d, palp; e, maxilla II; f, labrum and palp; g, enlarged view of labral crest. Lectotype (26-X1-14D), a-e, 
g; paralectotype(26-XI-14B), f. 



1970 



ROSS: STUDIES ON THE TETRACLITIDAE 



^0 05mm 

abed 0.5mm 






0.25 mm 
0.25 mm 





Figure 4. Thoracic appendages of Epopella breviscutum. a, left cirrus I; b, right cirrus II; c, right cirrus III; d, 
left cirrus III; e, comb seta from segment 5 of outer ramus of left cirrus III; f, intermediate segment of right outer 
ramus of cirrus VI; g,h. distal extremity of intromittant organ. Lectotype (26-XI-14D), b, c. f; paralectotypes, a, 
d. e. g-h (e,g.d = 26-XI-14C; a = 26-XI-14A; h = 2X-XI-14B). 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



36- 




















32i 










28- 








1 




0) 










- 




1- ^. 














z 24- 










^ 


r ^J 




UJ 












,-- 




2 












^ 






(D 












^ 
^ 


~^" 


m 










_ 




_ 


^"20- 




_ 


_ 




1 


. 


_ 


li- 










1 















1 

1 




Sl6- 




_ 






1 

1 




1 




\ 




1 


_ 


D 




\ 






Z 




\ 


/ 




12- 






-V- 

-L 


ANTERIOR RAMUS 


8- 












n= 


(8) 


(7) 


(7) (8) (7) (7) 



III IV V 

CIRRUS 



VI 



36- 














32- 










28- 
24- 






; 
; 
/ 
; 

/ 
; 


\ 
\ 
\ 
\ 
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\ 


-- 


20- 






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12- 






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-i- 


POSTERIOR RAMUS 


8- 












n= 


(8) 


(7) (8) (8) (7) (8) 



Ill IV V 

CIRRUS 



VI 



Figure 5. Graph of range (vertical line) and mean values (dotted line) for cirral counts of anterior ramus (left) 
and posterior ramus (right) of Epopella breviscutum. 

bristles; distal extremity bears two large separate clusters of long setules (Fig. 4g). 

Embryos in mantle cavity average 0.10 x 0.22 mm. Stage I nauplii in mantle cavity 
average 0.1 2 x 0.20 mm. 

Remarks. — Broch illustrated the opercular plates and trophi of breviscutum, but 
failed to select a holotype. Because the specimen or specimens he figured are no longer 
available, the specimens here figured (opercular plates, figs. 2a-c, 3; trophi, figs. 3a-e, g; 
cirri, figs. 4b, c, are designated the lectotype (26-XI-14D), and the remaining specimens, 
of which I have seen 4, are designated paralectotypes (26-XI-14A-C, E). 



DISCUSSION 

Monometric shell growth, non-tubiferous and narrow or obsolete radii, and the orifice 
enlarged by attrition rather than diametric growth clearly establish E. breviscutum as a 
member of the tesseroporan group (Ross, 1969: 238). 

The space between the inner and outer lamina in Tetraclita is filled with a network of 
continuous longitudinal septa, which in effect create longitudinal tubes. These are more or 
less uniform in section, and occur in rows with the smallest and shortest tubes parallel to 
the outer lamina. In Tesseropora and Tesseroplax there is basically but one row of these 
tubes. Epopella breviscutum lacks an inner lamina, and thus is effectively solid walled. A 



1970 ROSS: STUDIES ON THE TETRACLITIDAE 9 

non-tubiferous or solid wall characterizes the geologically earliest chthamalids and 
balanids (Ross, 1965: 61; Ross and Newman, 1967:4; Newman, ZuUo and Wainwright, 
1967: 167). In the tesseroporan lineage, I interpret the evolutionary trend then as having 
been from a solid walled form with diametric growth (Ross, 1969: 240) to a solid walled 
form with monometric growth, such as E. breviscutum or an earlier related species, to 
Tesseropora with a single row of parietal tubes and not uncommonly secondary tubules, 
and terminating with Tetraclita. Tesseroplax, also with a single row of tubes, is an early 
derivative of Tesseropora. 

Much confusion exists over the systematic position o{ Elminius.\^rgQ\y because certain 
of the included species are morphologically similar to the Balanidae on one hand and to the 
Tetraclitidae on the other (Darwin, 1854: 346). Those similar to the Balanidae have a 
deeply notched or incised labrum (Moore, 1944: pi. 46), and an intromittent organ bearing 
a basidorsal point (Nilsson-Cantell, 1930: 225). Those similar to the Tetraclitidae have a 
shallow or slightly notched labrum (Broch, 1922: 341-342), lack the basidoral point, have 
complex setae on cirrus III (lacking in the Balanidae) that exhibits antenniformy (Moore, 
1944: 328), and there are gross similarities in the opercular plates. Additional morpholog- 
ical characters, especially in the shell, as noted below, strengthen the inference that at 
least two species of Eliminius, namely E. plicatus Gray and E. simplex Darwin, are 
tetraclitids rather than balanids. The criteria for forming this group are supported by the 
distribution of the species involved, all three occurring within the southeastern Australia- 
New Zealand region. 

The parietal plates in E. breviscutum are complex, not only because they are a laminate 
of calcareous and chitinous materials, but because the inner surface of the wall develops an 
elaborate irregular series of depending ridges or longitudinal septa. These undoubtedly 
impart rigidity and strength to the wall and provide a broad base of attachment and 
vertical support, much as in Emersonius and Chelonobia (Ross and Newman, 1967: 16). 
The internal structure of the parietes in E. plicatus is much like that of £. breviscutum, but 
in E. simplex the chitinous material occurs in a row of equidistantly spaced thin columns 
instead of continuous ribbons. 

In E. breviscutum irregularly scattered between the depending ridges are narrow 
tubules that in section are either oval, circular, or irregular. Similar surficial depressions 
occur in E. plicatus. E. simplex, Tesseropora (at the tips of the secondary longitudinal 
septa), Tetraclita (see Pilsbry, 1916: 252) and not uncommonly in Chthamalus. Since 
Epopella lacks an inner lamina these "tubules" are not homologous with the parietal tubes 
or secondary tubules of other tesseroporans. The functional significance of these tubules 
and depressions remains unknown. 

Secondary calcification of the parietal tubes in tesseroporans aids in maintaining the 
shell in environments where it is subjected to abrasion or corrosion. The shell in 
Tesseroplax is strengthened by apical filling of the parietal tubes, much as in Tesseropora 
and Tetraclita, and by the formation of transverse septa in the basal portion. In Epopella, 
deposition of a layer of calcium carbonate between the youngest series of longitudinal 
septa serves the same function. Henry (1957: 36) has suggested that in Tesseropora pacifica 
the shell is reinforced through development of elaborate, hollow, spinous processes that 
extend into the parietal tube cavities, but further work is needed to substantiate this. 

In the Balanomorpha there has been selection both for structural reinforcement of the 
shell (Darwin, 1854) and for the development in deep water forms of a protective 
mechanism against boring organisms (Newman and Ross, in press). However, Epopella 
and other tesseroporans in general differ from these deep water forms in having a relatively 
much thicker and more complex wall. The development of a thick, laminated shell in the 



10 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

tesseroporans is probably an adaptation for the rigors of the intertidal zone (cf. Paine, 1966). 
There is a considerable interval between the earliest known occurrence (Recent) of the 
evolutionary more primitive Epopella and of the more complex Tesseropora (Oligocene). 
Thus the Epopella lineage must be significantly older than the fossil evidence indicates, a 
conclusion that is also suggested by the morphologically complex shell of E. breviscutum. 
Therefore, it seems probable that the origin of the tetraclitids should be sought in rocks 
dating from the Eocene if not the Paleocene or Cretaceous. 

ACKNOWLEDGMENTS 

I am indebted to Dr. Torben Wolff, Universitetets Zoologiske Museum, for the extended loan of Broch's 
type series of this species as well as other tetraclitids collected during the Th. Mortensen expeditions. Elizabeth 
Pope of the Australian Museum kindly searched the collections in her charge on numerous occasions for 
specimens, which she has made available to me. Thanks are also due Dr. William A. Newman, Scripps Institution 
of Oceanography, for many invaluable discussions relating to various aspects of this and earlier studies on the 
Tetraclitidae. For comparative material and other courtesies I thank Dr. Huzio Utinomi, Seto Marine Biological 
Laboratory, Dr. Elizabeth J. Batham, Portobello Marine Biological Station, New Zealand, Dr. Victor A. Zullo, 
California Academy of Sciences, and Brian Foster, University College of North Wales. 

LITERATURE CITED 

Broch, H. 

1922. Papers from Dr. Th. Mortensen's Pacific Expedition 1914-1916. X. Studies on Pacific cirripeds. 
Vidensk. Meddel. Dansk Naturhist. foren. Copenhagen 73: 215-358. 

Darwin, C. R. 

1854. A monograph on the sub-class Cirripedia, with figures of all the species. The Balanidae (or sessile 
cirripedes): the Verrucidae etc.. etc., etc. London, Ray Society, 1-684, pis. 1-30. 

Foster, B.A. 

1967a. A guide to the littoral balanomorph barnacles of New Zealand. Tuatara 1 5 (2); 75-86. 
1 967b. The early stages of some New Zealand shore barnacles. Tane 1 3: 33-42. 

Henry, D. P. 

1957. Some littoral barnacles from the Tuamotu, Marshall, and Caroline Islands. Proc. U.S. Natl. Mus. 
107 (3381): 25-38. 

Hiro, F. 

1939. Studies on the Cirripedian fauna of Japan. IV. Cirripeds of Formosa (Taiwan), with some 
geographical and ecological remarks on the littoral forms. Mem. Coll. Sci., Kyoto Imp. Univ., ser. B, 

15 (2): 245-284. 

Linzey, J. T. 

1942. The balanomorph barnacles of the Kermadec Islands. Trans. Roy. Soc. New Zealand 71: 279-281. 

Moore, L. B. 

1944. Some intertidal barnacles of New Zealand. Trans. Roy. Soc. New Zealand 73 (4): 315-334, pis. 46-47. 

Newman, W. A., and A. Ross 

MS. Antarctic Cirripedia: A monograph based on the collections of the USNS Eltanin Expeditions. Amer. 
Geophys. Union, Antarctic Res. Ser.. in press. 
Newman, W. A., V. A. Zullo, and S. A. Wainwright 

1967. A critique on recent concepts of growth in Balanomorpha (Cirripedia: Thoracica). Crustaceana 12 (2): 
167-178. 

Nilsson-Cantell, C. A. 

1930. Thoracic cirripedes collected in 1925-1927. Discovery Repts. 2: 223-260. 

Paine, R. T. 

1966. Function of labial spines, composition of diet, and size of certain marine gastropods. Veliger 9(1): 
17-24. 
Pilsbry, HA. 

1916. The sessile barnacles contained in the collection of the U.S. National Museum: including a 
monograph of the American species. Bull. U.S. Natl. Mus. 93: 1-366. 



1970 ROSS: STUDIES ON THE TETRACLITIDAE 11 

Pope, E. C. 

1945. A simplified key to the sessile barnacles found on the rocks, boats, wharf piles and other installations 
in Port Jackson and adjacent waters. Rec. Australian Mus. 21 (6): 351-372, pis. 27-30. 

Ross, Arnold 

1 965. A new cirriped from the Eocene of Georgia. Quart. J. Florida Acad. Sci. 28(1): 59-67. 
1969. Studies on the Tetraclitidae (Cirripedia: Thoracica): Revision of Tetraclita. Trans. San Diego Soc. 
Nat. Hist. 15(15): 237-251. 

Ross, A., and W. A. Newman 

1967. Eocene Balanidae of Florida, including a new genus and species with a unique plan of "turtle- 
barnacle" organization. Amer. Mus. Novitates 2288: 1-21. 

Stephenson, W. 

1968. The intertidal acorn barnacle Tetraclita vitiata Darwin at Heron Island. Univ. Queensland Pap. 1 (3): 
51-59. 

Wisely, B.,and R. A. P. Blick 

1964. Seasonal abundance of first stage nauplii in 10 species of barnacles at Sydney. Australian Jour. Mar. 
Freshwater Res. 15(2): 162-171. 



Department of Invertebrate Paleontology, Natural History Museum. P.O. Box 1390, 
San Diego, California 92112. 




MUS. COMP. ZOOL. 
LIBRARY 

JUN16 1970 

HARVARD 
UNIVERSITY 



THE SHALLOW WATER ANOMURAN CRAB FAUNA 
OF SOUTHWESTERN BAJA CALIFORNIA, MEXICO 



JANET HAIG, THOMAS S. HOPKINS 
AND THOMAS B. SCANLAND 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



VOL. 16, NO. 2 4 JUNE 1970 



THE SHALLOW WATER ANOMURAN CRAB FAUNA 
OF SOUTHWESTERN BAJA CALIFORNIA, MEXICO 



JANET HAIG, THOMAS S. HOPKINS 
AND THOMAS B. SCANLAND 



ABSTRACT. - Thirty-five species of anomuran crabs are reported from the 1964 "Mag Bay" Expedition, 
19 orv\hich are new records for the outer coast of southern Baja California, Mexico. A checklist and keys are 
appended for the 52 species of Anomura nov\ known to inhabit this area. 

RESUMEN. — Durante la Expedicion "'Mag Bay" en 1964, se observaron treinta y cinco especies de 
cangrejos anomuros, diez y nueve de ellas encontradas por primera vez, en las costas occidentales de la zona 
meridional de Baja California. Mexico. Se incluye una lista y las claves correspondientes para las 52 especies 
de Anomuros observados hasta la fecha en aquellas regiones. 

The purpose of the "Mag Bay" Expedition of 1964 was to study the maritime biota 
along the coast of Baja California, Mexico, from Punta San Eugenio (Punta Eugenia) to 
the lower entrance of Bahfa Magadalena (Figs. 1, 2). Dr. Carl L. Hubbs, Scripps 
Institution of Oceanography, was the originator and leader of the expedition, which was 
supported by the Office of Naval Research. The scientific party was divided into three 
teams: Team 1, aboard the R/V HORIZON, was responsible for sampling in deep water; 
Team 2, in small craft, worked in the mangrove-estuarine environment; Team 3, aboard 
the Scripps vessel T-441, was responsible for "on site" fish poisonings, invertebrate and 
algal collecting, and otter trawling along the 20- and 40 m depth contours in the area of 
study. 

Two of the authors (TSH and TBS) were members of Team 2, where SCUBA was 
used in depths of one to 30 meters. A concerted effort was made to collect decapod 
crustaceans and echinoderms, as well as fish. The specimens were returned to the T-441, 
where they were kept alive until color notes and tentative identifications could be recorded. 
At the conclusion of the cruise, the anomuran crabs were forwarded to the Allan Hancock 
Foundation for study by the senior author (JH). 

Thirty-five species of Anomura were collected, of which 19 constitute new records for 
the outer coast of southern Baja California (Punta San Eugenio and southward) within the 
40 m contour. A checklist and keys to all species known to fall within these geographical 
and bathymetrical limits are appended. 

This report is a Contribution from the Allan Hancock Foundation, no. - 339 , 
supported by NSF Grant GB-2039, and a Contribution from the Scripps Institution of 
Oceanography, supported by NSF Grant GB 2312 (to D. L. Fox). 

HISTORICAL RESUME 

The following anomuran crabs are presently known from the region under consid- 
eration: Miinida mexicana (Benedict, 1902), Dardaniis sinistripes (Rathbun, 1910), Pleu- 
roncodes planipes, and Emerita analoga (Schmitt, 1921). In addition, Glassell (1936) 
reported on several porcellanids which he collected at Bahfa Magdalena. These included 
Petrolisthes hirtipes (Lockington), and the new species Orthochela pumila. Pisosoma erosa 
{ = Megalobrachium erosum), and Porcellana magdalenensis ( = Pisidia magdalenensis). 
He also treated the porcellanid and hermit crabs from the Templeton Crocker Expedition of 

SAN DIEGO SOC. NAT. HIST.. TRANS. 16 (2): 13-32, 4 JUNE 1970 



14 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 1. Map of Baja California, Mexico. Area delimited by the box on the western side of the peninsula is 
shown enlarged in figure 2. 



1936 (Glassell, 1937a, 1937b). However, only one species comes within the scope of the 
present work, Paguristes bakeri Holmes, which was collected otT Isla Cedros (Glassell, 
1937b.) Schmitt (1939) listed "Paguristes species'' from Bahfa Magdalena, a form still 
awaiting description. To the known fauna Haig (1960) added 16 species of Porcellanidae. 



1970 



HAIG, HOPKINS AND SCANLAND: ANOMURAN CRABS 




Figure 2. Map of Bahia Magdalena region, Baja California, Mexico. 

The presence of 19 additional species in this fauna, and the larger number of new 
records, attests to the effectiveness of SCUBA in an area already well surveyed by dredging 
and intertidal collecting. 



ANNOTATED SPECIES LIST 
Family COENOBITIDAE 

Coenobita compressus H. Milne Edwards 

Cenobita compressa H. Milne Edwards, 1837: 241. 

Coenobita compressus -.Boone, 1931: 145, text-fig. 3; Holthuis, 1954: 16, text-figs. 4a-b. 

Recorded Range. — Santa Rosalfa, Golfo de California, to Estrecho de Magallanes. 
Islas Revillagigedo; Isla del Coco; Archipielago de Galapagos. 

Material. — Punta Belcher; above high tide at night; 2 Feb. 1964; Id', 2 9. 

Remarks. — Glassell (1937b: 242-243) stated: "For the most part these terrestrial 
hermit crabs inhabit the land bordering on the sea. They select heavy shells for their abode. 
They are, in the main, vegetarians, though they do not limit their diet and may at times act 
as scavengers, or become carnivorous ... In addition they are good tree climbers." 



16 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

On Punta Belcher we observed that these animals are nocturnal. A search for their 
homesites was fruitless, although the crabs "appeared" within 17m of the camp just after 
dark, and could not be found after daybreak. Probably they had remained inactive in their 
shells along the upper tide marks during the day, and thus went unnoticed. 

Six to 10 individuals were observed feeding on dead or molted Pleuroncodes planipes 
which formed windrows on the beach. 

The range of this species is extended to the outer Baja California coast, and 300 km 
north along the outer coast. 

Family DIOGENIDAE 

Dardanus sinistripes (Stimpson) 

Pagurus sinistripes Stimpson, 1858: 22i (nom. nud): \S59: S2. 
Dardanus sinistripes: Glassell, 1937b: 251. 

Recorded Range. — Bahfa Magdalena (Rathbun, 1910) and Isla Tiburon, Golfo de 
California, to Bahfa de Sechura, Peru. 

Material. — Off Boca de Santo Domingo; otter trawl; 40 m; 27 Jan. 1964; 1 ? . Laguna 
de Santa Maria: 1.2 m; 29 Jan. 1964; Id". 

Color. — "In alcohol, the carapace is buff with red markings. The chelipeds, purple 
and red, with the interior margins of the meri white; the teeth of the fingers white, bordered 
with yellow. The ambulatory legs are purple, their dactyli with dark brown setae, their 
meri and carpi blotched on a light ground with red" (Glassell, 1937b). There are two 
narrow, dark bands, one median and the other proximal, on the eyestalk. 

Calcinus californiensis Bouvier 

Calcinus californiensis Bouvier, 1898: 380; Glassell, 1937b: 252. 
Calcinus californiensis: Chace, 1962: 627, text-figs. 5-6. 

Recorded Range. — Isla San Jose, Golfo de California, to Acapulco, Me'xico. Isla 
Clipperton. 

Material. — Punta Cala; 3 m; 31 Jan. 1964; Id, 1 ?. 

Roca de la Vela;6 m; 1 Feb. 1964; 2$. Inside Punta Tosca, in lagoon; 5 m; 4 Feb. 
1964; 5c^, 2 9. 

Color. — The coloration of this and allied species, in both live and preserved material, 
was discussed in some detail by Chace (1962: 628). A broad white band at the base of the 
cornea and the solid dark color of the dactyls of the walking legs unmistakably identify the 
above specimens as Calcinus californiensis. 

Remarks. — The range of this species is extended to the outer Baja California coast, 
and 300 km north. 

Aniculus elegans Stimpson 

Aniculus elegans Stimpson, 1858: 234 («om. nud.): 1859: 83; Boone, 1931: 140, text-fig. 1. 

Recorded Range. — Golfo de California (exact locality not stated) to Cabo de San 
Francisco, Ecuador. 

Material. -Outside Bahfa Magdalena; 18 m; 1 Feb. 1964; 1 juv. Inside Punta Tosca, 
in lagoon; 5 m; 4 Feb. 1964; 1 ?. Off Punta Redonda; 15 m; 5 Feb. 1964; 6d", 5?. 

Color. — Carapace red, with a pink area on the posterior part of the shield. Eyestalks 
tan. Chelipeds pink, with red on the fingers and on the distal half of the chelae. Dactyls of 
walking legs dark- red; other segments pink. A broad, submedian red band on the 
propodus, a submedian red blotch on the anterior margin of the carpus, and a smaller 
median blotch on the anterior margin of the merus. 

Remarks. — Off Punta Redonda these hermits occurred under rocks in aggregates of 



1970 HAIG, HOPKINS AND SCANLAND: ANOMURAN CRABS 17 

five or more. Porcellana paguriconviva Glassell were found in the shells of specimens 
collected at the same locality, an association that has not been recorded previously. 

The range of this species is extended to the outer Baja California coast, and 300 km 
north. 

Trizopagurus magnificus (Bouvier) 

Clibanarius magnificus Bouvier, 1898: 378. 
Clibanarius chetyrkini Boone, 1932: 29, text-fig. 8. 
Trizopagurus magnificus: Forest, 1952: 4, 12, text-figs. 2, 11, 18. 

Recorded Range. — Golfo de California (exact locality not stated) to Isla de la Plata, 
Ecuador. Archipielago de Galapagos. 

Material. — Roca de la Vela; 6 m; 1 Feb. 1964; 1 ?. Off Punta Redonda; 15 m; 5 Feb. 
1964; 15. 

Color. — The species may be readily identified by the large, irregular pale blotches on 
a dark background which cover the carapace shield, eyestalks, chelipeds, and walking legs. 

Remarks. — The range of this species is extended to the outer Baja California coast, 
and 300 km north. 

Clibanarius panamensis Stimpson 

Clibanarius panamensis Stimpson, 1858:235 (nom nud.): 1859: 84; Holthuis, 1954: 23, text-figs. 7-8. 

Recorded Range. — Santa Rosalfa, Golfo de California, to Isla de la Correa, Peru. 

Material. — Laguna de Santa Marfa; in +1 m and out of water; 29 Jan. 1964; 8c?, 1 ?. 

Color. — Hermits of this species may be recognized immediately by the color pattern 
of the walking legs, which consists of longitudinal dark and light stripes, subequal in width, 
on each segment. 

Remarks. — The range of this species is extended to the outer Baja California coast, 
and 300 km north. 

Isocheles pilosus (Holmes) 

Hoiopagurus pilosus Holmes, 1900: 154;Schmitt, 1921: 127, pi. 17 fig. 2; Ricketts and Calvin, 1939: 189, pi. 39 
fig. 2. 

Isocheles pilosus: Forest, 1964: 294. 

Recorded Range. — Off San Francisco Bay, California, to Estero de Punta Banda, 
outer Baja California. 

Material. — Punta Abreojos, Bahfa de Ballenas; +.7 m while wading; 29 Jan. 1964; 
1 . 2.5 miles west of Boca de Santo Domingo; 16' otter trawl; 14-20 m; 26 Jan. 1964; Id". 
Outside Punta Hughes; 20 m; 30 Jan. 1964; 1 2 (juv.). Punta Pequena, Bahfa de San 
Juanico; 3 m; 8 Feb. 1964; Id", 1 juv. 

Remarks. — Identification of the above specimens with Isocheles pilosus is tentative, 
pending a revision of genus Isocheles by J. Forest of the Muse'um National d'Histoire 
Naturelle, Paris. Some of the material may belong to /. pacificus Bouvier (see Forest, 
1964: 291, text-fig. 11). Neither /. pilosus nor /. pacificus has heretofore been reported 
from the outer coast of southern Baja California, and the range is extended 850 km south. 

Paguristes bakeri Holmes 

Paguristes bakeri Holmes. 1900: 152;Schmitt, 1921: 122, 124, pi. 18 figs. 2, 6; Glassell, 1937b: 243, 244. 
Paguristes holmesi Glassell, 1937b: 243, 247. 

Recorded Range. — Outside San Francisco Bay, California, southward along the 
California and outer Baja California coast (Glassell, 1937b; Parker, 1964), and in Golfo de 
California as far north as Punta Baja. 

Material. — HORIZON Sta. A-11, 8 miles west of Punta Redonda; Isaacs-Kidd 



18 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

midwater trawl, scraped on sand bottom; 106-1 16 m; 29 Jan. 1964; 1 juv. 

Remarks. — Studies now in progress by JH indicate that Paguristes holmesi is a 
synonym of P. bakeri Holmes. Paguristes bakeri has been recovered from shallow water 
(generally in the northern half of its range), but it occurs more commonly in over 40 m and 
has been reported from depths as great as 232 m. 

Paguristes ulreyi Schmitt 

Paguristes ulreyi Schmitt, 1921: 123, 125, pi. 18 figs. 3-5, 7. 
Paguristes occator Glassell, 1937b: 243, 244. 

Recorded Range. — Monterey Bay, California, southward along the California and 
outer Baja California coast, and in Golfo de California as far north as Punta Gorda. 

Material. — Bajio Knepper, Punta Abreojos; 17-20 m; 9 Feb. 1964; 1 ? ovig. Bahia 
de San Hipolito; 10-13 m; 9 Feb. 1964; 5cf, 3$ovig., 1 juv. Without data; Id", 2 9(1 
ovig.), 2 juv. 

Remarks. — Examination of specimens in the collections of the Allan Hancock 
Foundation indicates that this species is not uncommon in the southernmost part of 
Golfo de California, where it occurs in deeper water than it does in higher latitudes. 
Paguristes occator Glassell seems to be a synonym. 

Paguristes parvus Holmes 

Paguristes parvus Holmes, 1900: 151, pi. 2 fig. 26; Schmitt, 1921: 123, 124, pi. 17 fig. 1, text-fig. 83. 

Recorded Range. — Known only from White's Point near San Pedro, California. 

Material. — Arrecife Sacramento; 13 m, from kelp holdfast; 25 Jan. 1964; IcT. 

Remarks. — On the basis of the above specimen, the range of Paguristes parvus is 
extended southward 550 km. 

Paguristes anahuacus Glassell 
Paguristes anahuacus Glassell, 1938:421. 

Recorded Range. — Reported only from Punta Penasco, Golfo de California. 

Material. — Outside Punta Hughes; 20 m; 30 Jan. 1964; 1 d. Roca de la Vela; 6 m; 1 
Feb. 1964; Id", 1 ?. Outside Isla Santa Margarita, west of Punta Tosca; 21-25 m; 3 Feb. 
1964; 19. Off Punta Redonda; 15 m; 5 Feb. 1964; Icf, 19. Bajfo Knepper, Punta 
Abreojos; 16-20 m; 9 Feb. 1964; 119. Without data; 3 9 ovig. 

Color. — Carapace shield with a broad median longitudinal orange stripe on ante- 
rior half; orange blotches on median portion of lateral margins. Proximal half of eyestalk 
orange; distal half bright purple, with a narrow white band at base of cornea. Antennal 
and antennular flagella purple. Pereiopods orange. 

Remarks. — Punta Penasco is 1000 km north of Cabo San Lucas on the mainland 
side of the Gulf. The range of this species is further extended to the outer coast of Baja 
California, and 550 km north. 

Paguristes praedator Glassell 

Paguristes praedator Glassell, 1937b: 243, 245. 

Recorded Range. — Golfo de California, from Bahfa de Santa Ine's and Isla Tiburon 
south to Isla Isabel. 

Material. — Off Boca de Santo Domingo; 16' otter trawl; 40 m; 27 Jan. 1964; 1 juv. 

Remarks. — Examination of a long series of specimens in the collections of the Allan 
Hancock Foundation shows that this species occurs infrequently within the 40 m line; it has 
been most often dredged in 60 m or deeper. The range is extended to the outer Baja 
California coast, and 350 km north. 



1970 HAIG, HOPKINS AND SCANLAND: ANOMURAN CRABS 19 

Paguristes, undescribed species 

Paguristes species, Schmitt, 1939:9. 

Material. — Off Boca de las Animas; 16' otter trawl; 40 m; 27 Jan. 1964; Id" (juv.). 
Off Boca de Santo Domingo; 1 6' otter trawl; 40 m; 27 Jan. 1964; 2 cT ( 1 juv.). 

Color. — Carpus of chelipeds red; chelae white with red blotches, which merge to 
form a transverse band about midway along each finger. Walking legs white; propodus and 
dactyl each with a proximal and subdistal red ring. 

Remarks. — This species, which will be described and illustrated in a future report, 
appears to be abundant on the outer Baja California coast. The ovigerous female noted by 
Schmitt (1939) was collected by the HOUSTON (Presidential Cruise of 1938) in Bahfa 
Magdalena between Punta Belcher and the anchorage, in 20-30 m. 

Family PAGURIDAE 

Pagurus smithi (Benedict) 

Eupagurus smithi Benedict, 1892: 4. 
Pagurus smithi: Glassell, 1937b: 256, 259. 

Recorded Range. — Golfo de California, from Estero de Tasiota to Punta Piaxtla on 
the east side (Parker, 1964) and from Bahia de Santa Ines to Bahia de la Paz on the Baja 
California peninsula. 

Material. — Off Boca de Santo Domingo; 16' otter trawl; 40 m; 27 Jan. 1964; 2 juv. 

Remarks. — This species is well represented in the collections of the Allan Hancock 
Foundation from depths greater than 40 m; it seems to occur rarely within the 40 m 
contour. The range is extended 150 km south to the outer Baja California coast, 350 km 
north along the outer coast. 

Pagurus, undescribed species (1 ) 

Material. — Off Boca de las Animas; 16' otter trawl; 20 and 40 m; 27 Jan. 1964; Id, 
2 9ovig., 3 juv. 

Remarks. — This small species, represented by considerable material in the collec- 
tions of the Allan Hancock Foundation, will be described elsewhere. It belongs to the 
group of Pagurus species having multispinulate eyescales. 

Pagurus lepidus (Bouvier) 

Eupagurus lepidus Bouvier, 1898:381. 
Pagurus lepidus: Glassell, 1937b: 256. 
? Pagurus lepidus: Chace, 1962: 623, text-fig. 2. 

Recorded Range. — Golfo de California, from Puerto Penasco to El Mogote. ?Isla 
Clipperton. 

Material. — Off Boca de Santo Domingo; 16' otter trawl; 40 m; 27 Jan. 1964; Icf, 1? 
ovig. Outside Punta Hughes; 20 m; 30 Jan. 1964; 4cf, 1 ? ovig. Punta Cala; 3 m; 31 Jan. 
1964; 1 juv. Outside Bahfa Magdalena; 20 m; 1 Feb. 1964; 2cf. Isla Santa Margarita; 16' 
otter trawl; 20 m; 4 Feb. 1964; Id", 1$. Punta Redonda; 15 m; 5 Feb. 1964; id'. Punta 
Pequena, Bahfa de San Juanico; 3 m; 8 Feb. 1964; 2d', 1 ?. Bahfa de San Hipolito; 10-13 m; 
9 Feb. 1964; 3d", 2 9 (1 ovig.). Bajfo Knepper, Punta Abreojos; 16-20 m; 9 Feb. 1964; 7d", 
69(3 ovig.), 1 juv. 

Color. — Most of the specimens showed a color pattern on the walking legs like that 
in Chace's illustration (1962, text-fig. 2). In a few individuals the longitudinal stripes were 
less well developed, and pigment was concentrated at the proximal end of the dactyl to 
form a narrow ring. Current studies by JH show that there is a series of eastern Pacific 
Pagurus species closely allied to P. lepidus and probably confused under that name; this 



20 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

problem, as it concerns the "Mag Bay" material, will be discussed elsewhere. 

Remarks. — The range of this species is extended to the outer Baja California coast 
and 550 km north. 

Pagurus galapagensis (Boone), new combination 
N ympagurus galapagensis Boone, 1932: 17, text-fig. 5. 

Recorded Range. — Known only from Bahia de Gardner, Isla Hood (or Espanola), 
Archipielago de Galapagos. 

Material. — Roca de la Vela; 6 m; 1 Feb. 1 964; 1 d', 1 9 . 

Color. — Hand under dense tomentum pale orange, with tubercles of darker orange; 
fingers white with an intense orange spot at tip of each. Walking legs with longitudinal 
orange stripes, overlying a broad median orange ring on carpus and propodus and two 
rings on dactyl. 

Remarks. — Studies currently in progress by JH indicate that this species occurs 
throughout the Panamic faunal province. Examination of the holotype (Cat. No. 12238 in 
the American Museum of Natural History, New York) showed that it falls within Pagurus 
as that genus is currently (although too broadly) defined. Its affinities are with a natural 
group o{ Pagurus species recently discussed and designated as "groupe miamensis" (Forest 
and Saint Laurent, 1968: 116). 

Pagurus, undescribed species (2) 

Material. — HORIZON Sta. A-11; 8 miles west of Punta Redonda; Issacs-Kidd 
midwater trawl scraped on sand bottom; 106-1 16 m; 29 Jan. 1964; 2d", 29(1 ovig.). 

Remarks. — This species has been collected on several occasions around the southern 
part of the Baja California peninsula, never in less than 104 m. It will be described in a 
future report. 

Pylopagurus californiensis (Benedict), new combination 

Eupagurus californiensis Benedict, 1892: 21; Faxon, 1895: 55, pi. 1 1 figs. 2, 2a-f. 
Pagurus californiensis: Glassell, 1937b: 256, 257. 

Recorded Range. — Santa Catalina Island, California, and Cabo Tepoca, Golfo de 
California, to Darfen, Panama. Isla del Coco; Archipielago de Galapagos. 

Material. —Outside Bahfa Magdalena; 20 m; 1 Feb. 1964; Id". Without data; Id". 

Color. — Carapace shield with longitudinal dark and light streaks anteriorly; solid 
color toward anterolateral margins. Eyestalks orange, with broad white ring submedially. 
Basal antennal article and acicle orange; acicle darker along outer edge. Manus and fingers 
of major cheliped with diffused orange; raised granular areas white; outer margin with 
alternating while and orange spots. Carpus solid dark orange except for narrow longitudi- 
nal white area along inner margin, and a few very small white spots on dorsal surface. 
Merus mostly orange, with small white spots. Manus of minor cheliped with a large 
irregular orange area on dorsal surface; a longitudinal orange stripe, not continued far 
onto pollex, along outer edge. Carpus with thin orange stripe along each dorsolateral 
margin; a broader stripe midway along both outer and inner lateral surfaces; another along 
ventral surface. Merus of walking legs with two longitudinal red stripes on outer surface, 
one on upper margin, and two on inner surface; carpus with three on outer surface, one on 
dorsal margin, and two on inner surface; propodus with two on outer surface, one on dorsal 
margin, one on ventral margin, and two on inner surface; dactyl with one each on outer 
surface, dorsal margin, and inner surface. With the exception of those on inner surface of 
merus, which are incomplete, none of these stripes are interrupted. All these stripes are 
imposed on broad transverse bands of white and pale orange. 



1970 HAIG, HOPKINS AND SCANLAND: ANOMURAN CRABS 21 

Remarks. — This species, and the two that follow, have not been recognized as 
members of the genus Pylopagurus and were consequently not included in Walton's (1954) 
review of the eastern Pacific forms of that genus. The shape of the major chela and the 
presence of paired first pleopods in the female place all three species with Pylopagurus. 

Although there are no published records of Pylopagurus californiensis along the outer 
coast of Baja California, the distribution between Santa Catalina Island and Bahfa 
Magdalena is not interrupted; specimens from many intermediate localities are in the 
collections of the Allan Hancock Foundation. 

Pylopagurus venustus (Bouvier), new combination 
Eupagurus venustus Bouvier, 1898: 383. 

Recorded Range. — Known only from Bahia de la Paz, Golfo de California. 

Material. — Outside Punta Hughes; 20 m; 30 Jan. 1964; 1 ? ovig. 

Color. — Ground color white and pale orange, with darker shades of orange-brown. 
Carapace pale brown, with two irregular small brown blotches anteriorly. A narrow band 
of pale orange on eyestalks at about level of tip of eyescales. Major chela with irregular 
diffused brown except on fingers and distal half of lateral expansion. A few small dots on 
fingers. Other segments of major cheliped with irregular blotches; darker on lateral 
surfaces. Minor cheliped with two broad bands on manus, one on carpus, one on hand and 
basal part of fingers; these bands are brown, edged in darker brown, and with an irregular, 
sinuous outline. Walking legs with similar, sinuous-margined bands: two on merus, a distal 
one on carpus, a median one on propodus, and a proximal one on dactyl. Non-banded 
areas white and very pale orange. 

Remarks. — The characteristic broad bands with sinuous margins which decorate the 
walking legs unfortunately fade rapidly in alcohol; specimens can then best be distin- 
guished from faded specimens of Pylopagurus californiensis by the carpus of the right 
cheliped, which in P. venustus is covered dorsally by numerous forward-directed spinules. 

The range is extended 150 km south to the outer Baja California coast, and 300 km 
north along the outer coast. 

Pylopagurus roseus (Benedict), new combination 

Eupagurus roseus Benedict, 1892: 22. 

Recorded Range. — The type locality was given only as "Gulf of California" by 
Benedict. According to the accompanying label, however, the holotype and only known 
specimen was collected off Bahfa Adair, in the northernmost part of the Gulf, 1000 km 
north of Cabo San Lucas. 

Material. ~ North of Punta Belcher; 8 m; 2 Feb. 1964; Id", 1?. Punta Cala; 5 m; 6 
Feb. 1964; Ic/, 2 9 ovig. 

Color. — Eyestalks white, with broad orange band at about level of tips of eyescales. 
Chelipeds orange-brown; carpus with many small white spots. Walking legs orange-brown; 
merus with large white blotches; propodus and dactyl each with a broad, subdistal white 
ring and a distal narrower one. 

Remarks. — The range is extended to the outer Baja California coast, and 300 km 
north. 

Pylopagurus diegensis Scanland and Hopkins 

Pylopagurus diegensis Scanland and Hopkins, 1969: 257, fig. 1. 

Material. — Uncertain locality data; 1 9 . 

Remarks. — This species has been collected at several localities in southern California 
and northern Baja California. 



22 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Family GALATHEIDAE 
Pleuroncodes planipes Stimpson 

Pleuroncodes planipes Stimpson, 1860: 245; Schmitt, 1921: 163, pi. 31 fig. 2. 

Recorded Range. — Monterey Bay, California, and northern Golfo de California, to 
about 250 km south of Cabo San Lucas. 

Material. — These crabs were very abundant at the surface just inside Punta Entrada 
and many were collected during the expedition but were not critically examined. Large 
windrows of either dead or molted individuals littered the beach just south of Punta 
Belcher and were fed on by Coenobita compressus. 

Remarks. — Pleuroncodes planipes normally ranges from Baja California southward; 
Radovich (1961: 49-50) discussed the history of its occurrence off the California coast 
during p)eriods of high ocean temperatures. Crabs of this species are pelagic, frequently 
occurring near the surface in swarms several miles wide, and may be washed ashore in 
great numbers; at other times they are not visible near the surface, but may be taken by 
mid-depth or bottom trawling (Radovich 1961: 50). Swarming and mass strandings on the 
outer coast of southern Baja California were noted by several authors, including Matthews 
(1932: 472), Steinbeck and Ricketts (1941: 455), and Radovich (1961: 50). 

Family PORCELLANIDAE 

Orthochela pumila Glassell 

Orihochela pumila Glassell, 1936: 296, pi. 21 fig. 1; Haig. 1960: 14, pi. 18 fig. 1, text-fig. 1. 

Recorded Range. — Bahia Magdalena, outer Baja California, and Mazatlan, Mexico, 
to Bahfa de Caraquez, Ecuador. 

Material. — Inside Punta Hughes; 3-8 m; 29 Jan. 1964; 19d", 21 ? (18 ovig.), 1 juv. 
Near Mexican naval establishment at Puerto Cortez, northwest end of Bahia de Almejas; 
1.5 m; 5 Feb. 1964; 1 . Punta Pequelia, Bahfa de San Juanico; 3 m; 9 Feb. 1964; Id, 6 9 (4 
ovig.). Bahfade San Hipolito; 10-13 m; 9 Feb. 1964; 46^, 3? ovig. 

Color. — The specimens collected and described by Glassell were yellow, with red 
striations on the carapace and some red areas on the chelae; they were found clinging to 
yellow gorgonian corals. During the "Mag Bay" expedition collectors took some yellow 
individuals with red markings; other specimens were solid purple; blotched red and yellow; 
brown with white spots; and white with rust-colored spots. Each specimen perfectly 
matched the color of the gorgonian coral upon which it was found. 

Remarks. — Several other porcellanids were found associated with Orthochela pu- 
mila on gorgonians. Unlike Orthochela. however, they are not obligatory commensals but 
take shelter in a variety of situations. 

Orthochela pumila was previously collected by Glassell at Bahfa Magdalena, the type 
locality. On the basis of specimens collected during this expedition, the range of the species 
is extended northward along the outer Baja California coast 300 km to Bahfa de San 
Hipolito. 

Petrolisthes sanfelipensis Glassell 

Petrolisthes sanfelipensis Glassell, 1936: 281; Haig, I960: 24, 30, pi. 20 fig. 3. 

Recorded Range. — Bahfa de San Juanico to BahTa Magdalena, outer Baja Califor- 
nia (Haig, I960); Punta Penasco to Guaymas, Golfo de California. 

Material. — Olitside Punta Hughes; 20 m; 30 Jan. 1964; 1 cT Ouv.). Near Mexican 
naval establishment at Puerto Cortez, northwest end of Bahfa de Almejas; 1.5 m; 5 Feb. 
1964; 1?. Punta Pequena, Bahfade SanJuanico; 3 m; 9 Feb. 1964; lc^(juv.). 

Remarks. — The specimen from Punta Pequena was taken from a gorgonian. The 



1970 HAIG, HOPKINS AND SCANLAND: ANOMURAN CRABS 23 

range of this species is now extended slightly northward in Bahia de San Juanico to Punta 
Pequena. 

Petrolisthes hians Nobili 

Petrolisthes hians Nobili. 1901: 17; Haig, 1960: 26, 121, pi. 22 fig. 3. 
Pisosoma flagraciliata Glassell, 1937a: 82, pi. 1 fig. 2. 

Recorded Range. — Bahfa de Santa Maria, outer Baja California, and Guaymas, 
Golfo de California, to Bahfa de Santa Elena, Ecuador. Islas Revillagigedo. 

Material. — Inside Bahia Magdalena about 300 m north of Punta Belcher; 6 m; 1 
Feb. 1964; 1 ovig. Inside Punta Tosca, in lagoon; 5 m; 4 Feb. 1964; 1 9 . 

Remarks. — The specimen from Punta Tosca was taken from a sponge. The only 
previous record for this species from the outer Baja California coast is from Bahia de 
Santa Marfa (Haig, 1960). 

Pachycheles marcortezensis Glassell 

Pachycheles marcorlezensis Glassell, 1936: 290; Haig, 1960: 134. 149, pi. 33 fig. 3. 

Recorded Range. — Bahfa de Santa Maria, outer Baja California (Haig, 1960); Isla 
Xngel de la Guarda to Banco Arena, Golfo de California. 

Material. — Off Isla Santa Margarita; otter trawl; 20 m; 4 Feb. 1964; 1 cf. 

Pachycheles panamensis Faxon 

Pachycheles panamensis Faxon, 1893: 175; 1895: 71, pi. 15 figs. 2, 2a; Haig, I960: 134, 155, pi. 33 fig. 1. 
Pachycheles sonorensis Glassell, 1936: 291. 

Recorded Range. — Isla Tiburon, Golfo de California, to Bahfa de Santa Elena, 
Ecuador. 

Material. — Inside Punta Hughes; 6 m; 29 Jan. 1964; 1 cT (]nv.). 

Remarks. — The specimen was collected from a yellow gorgonian. The range is 
extended to the outer Baja California coast, and 300 km north. 

Pachycheles pubescens Holmes 

Pachycheles pubescens Holmes, 1900: 1 10; Schmitt, 1921: 175, 177, pi. 33 fig. 4. text-fig. 1 12; Haig, 1960: 133, 
162, pl.'34fig. 3. 

Recorded Range. — Goose Island, British Columbia, to Cabeza de Thurloe, outer 
Baja CaHfornia (Haig, 1960). 

Material. — Without data; 1 juv. 

Pachycheles holosericus Schmitt 

Pachycheles holosericus Schmitt, in Nininger, 1918: 39, text-fig. 18 (nom. nud.) Schmitt, 1921: 175, 177, pi. 33 
fig. 3; Haig, 1960: 133, 173, pi. 34 fig. 2. 

Recorded Range. — Santa Barbara, California, to Bahfa Magdalena, outer Baja 
CaHfornia (Haig, 1960). 

Material. —Bahfa de San Hipolito; 10-13 m; 9 Feb. 1964; 3 juv. 
Remarks. — The specimens were collected from a gorgonian coral. 

Porcellana cancrisocialis Glassell 

Porcellana cancrisocialis Glassell, 1936: 292; Haig, 1960: 198, 200, pi. 38 fig. 2, text-fig. 9 (2). 

Recorded Range. — Bahfa de Santa Marfa and Punta Tosca, outer Baja California 
(Haig, 1960); Punta Penasco, Golfo de California, to Bahfa de Santa Elena, Ecuador. 

Material. — Off Bahi'a de San Juanico; 1 6' otter trawl; 40 m; 27 Jan. 1 964; 1 . 

Remarks. — Porcellana cancrisocialis is often found associated with large hermit 
crabs, but is sometimes free-living as was the above specimen. The range of this species is 



24 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

extended northward from Bahfa de Santa Maria 150 km to Bahfa de San Juanico. 

Porcellana paguriconviva Glassell 
Porcellana paguriconviva Glassell, 1936: 293; Haig, 1960: 198, 203, pi. 38 fig. 1, text-fig. 9 (3). 

Recorded Range. — Bahfa Magdalena, outer Baja California (Haig, 1960), and Punta 
Penasco, Golfo de California, to Islas Toboga and Taboguilla, Panama (Haig, 1962). 

Material. —Off Punta Redonda; 15 m; 5 Feb. 1964; 9d^, 4 9. 

Color. — Ground color in life bright lavender, with uniform longitudinal stripes of 
bright orange. Chelipeds bright lavender; legs with a white spot on propodus. Ventral side 
iridescent, pinkish white; longitudinal stripes on carapace continued on first three segments 
of abdomen (Glassell, 1936). 

Remarks. — The specimens were found living in shells in association with Aniculus 
elegans Stimpson. Porcellana paguriconviva was previously reported in association with 
two other large hermits, Petrochinis californiensis Bouvier and Paguristes digueti Bouvier. 

Pisidia magdalenensis (Glassell) 

Porcellana magdalenensis Glassell, 1936: 295; 1938: 431, pi. 32. 
Pisidia magdalenensis: Haig, 1960: 209, pi. 38 fig. 4, text-fig. 10. 

Recorded Range. — Bahia de Santa Maria, outer Baja California (Glassell, 1936), to 
Bahfa de Santa Elena, Ecuador. Apparently absent from Golfo de California. 

Material. — Inside Punta Hughes; 6 m; 29 Jan. 1964; 3^", 2 ?. Outside Punta Hughes; 
20 m; 30 Jan. 1964; IJ, 1 ? ovig. Off Isla Santa Margarita; otter trawl; 20 m; 4 Feb. 1964; 

Id". 

Remarks. — The specimens collected inside Punta Hughes were associated with 
yellow gorgonian corals. 

Megalobrachium garthi Haig 

Megalobrachium garthi Haig, 1957:39, pi. 10; 1960: 213, 220, pi. 16 fig. 7, pi. 39 fig. 4. 

Recorded Range. — Isla Turner, Golfo de California, to Puerto Utrfa, Colombia. 

Material. — Inside Punta Hughes; 6 m; 29 Jan. 1964; 1 cT. Outside Bahfa Magdalena; 
20 m; 1 Feb. 1964; 1 d- Inside Punta Tosca, in lagoon; 5 m; 4 Feb. 1964; 1 c5". 

Remarks. — The specimen from Punta Hughes was taken from a yellow gorgonian, 
and the one from Punta Tosca from a sponge. The range of this species is extended to the 
outer coast of Baja California, and 300 km north. 

Megalobrachium tuberculipes (Lockington) 
Pachycheles tuberculipes Lockington, 1878: 396, 404. 
Pisonella tuberculipes: Glassell, 1938: 437, 440, pi. 34 fig. 1. 
Megalobrachium tuberculipes: Haig. 1960: 213, 227, pi. 16 fig. 11, pi. 40 fig. 4. 

Recorded Range. — Punta Penasco and San Felipe, Golfo de California, to Bahfa de 
Santa Elena, Ecuador. 

Material. — Inside Punta Hughes; 6 m; 29 Jan. 1964: 1 cf , 1 ?. Inside Punta Tosca, in 
lagoon; 5 m; 4 Feb. 1964; 2 cf. Bahfa de San Hipolito; 10-13 m; 9 Feb. 1964; 19. 

Remarks. — Specimens were taken from a yellow gorgonian at Punta Hughes and 
from sponge at Punta Tosca. 

The range of this species is extended to the outer coast of Baja California, and 550 km 
north. 



1970 HAIG, HOPKINS AND SCANLAND: ANOMURAN CRABS 25 

APPENDIX 

The checklist and keys which follow include all species of anomuran crabs known to occur on the west 
coast of Baja California from Punta San Eugenio (Punta Eugenia) southward, in depths of 40 m or less. 
Nineteen of these species are included as a result of the expedition reported upon in the first part of this paper; 
26 species on the basis of published records; and 7 species on the strength of records, as yet unpublished, in the 
Allan Hancock Foundation of the University of Southern California. 

CHECKLIST OF ANOMURAN CRABS FROM 
SOUTHWESTERN BAJA CALIFORNIA, MEXICO 

Unpublished records are marked with an asterisk (*) 

Family HIPPIDAE 
Emerita analoga (Stimpson) 

Hippa analoga Stimpson, 1857: 85. Emerita analoga: Schmitt, 1921: 173, pi. 31 fig. 5, text-fig. IjO: 1935: 
214, 216, text-figs. 75a, b. Range: Alaska to southwest Baja California; also Peru and Chile. Bahfa de San 
Bartolome" (Schmitt 1921); Bahfa Magdalena (Schmitt 1935). 

Family ALBUNEIDAE 
Lepidopa niyops Stimpson 

Lepidops myops Stimpson, 1860: 241. Lepidopa myops: Schmitt, 1921: 172, pi. 31 fig. 4. Range: Southern 
California to Cabo de San Lucas, Golfo de California. *Bahia de Santa Marfa. 

Family COENOBITIDAE 
Coenobita compressus H. Milne Edwards. See p.l5 . 

Family DIOGENIDAE 
Dardanus sinistripes (Stimpson). See p. 16 . 
Calcinus calijorniensis Bouvier. See p.l6 . 
Petrochirus calijorniensis Bouvier. 

Petrochirus californiensis Bouvier, 1895: 6. Glassell, 1937b: 251. Range: northern Golfo de California to 

Ecuador. * Bahfa de Santa Marfa. 
Aniculus elegans Stimpson. See p. 16 . 
Trizopagurus magnificus (Bouvier). See p. 17 . 
Clibanarius panamensis Stimpson. See p. 17 . 
Isocheles sp. See p. 17 . 
Paguristes bakeri Holmes. See p. 1 7 . 
Paguristes ulreyi Schmitt. See p. 18 . 
Paguristes digueti Bouvier ^ 

Paguristes digueti Bouvier, 1893: 18, text-fig. 1-4. Glassell, 1937b: 243. Range: Golfo de California. *Bahia 

de Santa Marfa; * Bahfa Magdalena. 
Paguristes anahuacus Glassell. See p. 18 . 
Paguristes praedator Glassell. See p. 18 . 
Paguristes. undescribed species. See p. 19 . 

Family PAGURIDAE 

Pagurus gladius (Benedict) 

Eupagurus gladius Benedict, 1892: 7. Pagurus gladius: Glassell, 1937b: 256, 257. Range: Golfo de 
California to Ecuador. * Bahfa de Santa Marfa; *Bahia Magdalena; * Punta Tosca. 

Pagurus sniithi (Benedict). See p. 19 . 

Pagurus. undescribed species (1). See p. 19. 

Pagurus lepidus (Bouvier). See p. 19 , 

Pagurus galapagensis (Boone). See p. 20 . 

Pagurus samuelis (Stimpson) 

Eupagurus samuelis Stimpson, 1857: 86. Pagurus samuelis: Schmitt, 1921: 129, 139, pi. 16 figs. 2-3. text- 
fig. 90. Range: Northern California to northwest Baja California. *Punta San Eugenio; *Punta San 
Bartolome; *Bahia de Tortuga; * Punta Asuncion; * Punta Abreojos. 

Pylopagurus californiensis (Benedict). See p. 20 . 

Pylopagurus venustus (Bouvier). See p.21 . 

Pylopagurus roseus (Benedict). See p.21 . 

Family GALATHEIDAE 
Munida mexicana Benedict 



26 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Munida mexicana Benedict, 1902: 251, 264, text-fig. 13. Range: Northern Golfo de California to 

Archipielago de Galapagos. Bahia de Santa Maria (Benedict). 
Munida reful^ens Fa.xon 

Munida refulgens Faxon, 1893: 177; 1895: 75, pi. 17. Range: Southern Golfo de California to Panama. 

*Bahia Magdalena. 
Munida tenella Benedict 

Munida tenella Benedict, 1902: 252, 274, text-fig. 20. Range: Golfo de California. *Bahia Magdalena. 
Pleuroncodes planipes Stimpson. See p. 22. 

Family PORCELLANIDAE 
Orthochela pumila Glassell. See p. 22 . 
Petrolisthes sanfelipensis Glassell. See p. 22. 
Petrolisthes edwardsii (Saussure) 

Porcellana edwardsii Saussure, 1853: 366, pi. 12 fig. 3. Petrolisthes edwardsii: Haig, 1960: 24, 33, pi. 21. 

Range: Southwest Baja California and southern Golfo de California to Ecuador. Bahia de Santa Maria; 

Bahfa Magdalena (Haig). 
Petrolisthes hirlipes Lockington 

Petrolisthes hirtipes Lockington. 1878: 395, 397. Glassell, 1936: 284. Haig, 1960: 26, 60, pi. 24 fig. 3. 

Range: Golfo de California and southwest Baja California. Bahfa Magdalena (Glassell). 
Petrolisthes manimaculis Glassell 

Petrolisthes manimaculis Glassell. 1945: 223, text-fig. 1. Haig, 1960: 28, 77, pi. 27 fig. 1. Range: Northern 

California to southwest Baja California. Punta San Eugenio (Haig). 
Petrolisthes gracilis Stimpson 

Petrolisthes gracilis Stimpson, 1858: 227 (nom. nud.); \%59: 74. Haig, 1960: 28, 79, pi. 27 fig. 2. Range: 

Northern Golfo de California to southern Mexico. Bahia de Santa Maria (Haig). 
Petrolisthes cabrilloi Glassell 

Petrolisthes cabrilloa Glassell, 1945: 225, text-fig. 4. Petrolisthes cabrilloi: Haig, 1960: 28, 88, pi. 26 fig. 3. 

Range: Central California to southwest Baja California. Punta San Eugenio; Punta San Bartolome; Punta 

Asuncion; Punta Abreojos; Bahia de San Juanico; Bahia Magdalena (Haig). 
Petrolisthes crenulatus Lockington 

Petrolisthes crenulatus Lockington, 1878: 395, 398. Haig, 1960: 27, 110, pi. 23 fig. 4. Range: Golfo de 

California and southwest Baja California. Bahia Magdalena (Haig). 
Petrolisthes hians Nobili. See p. 23 . 
Pachycheles marcortezensis Glassell. See p. 23. 
Pachvcheles spinidactvlus Haig 

Pachycheles spinidactylus Haig, 1957: 31, pi. 7; 1960: 134, 153, pi. 33 fig. 2. Range: Southwest Baja 

California and southern Golfo de California to Colombia. Bahia de Santa Maria (Haig, 1960). 
Pachycheles panamensis Faxon. See p. 23. 
Pachycheles pubescens Holmes. See p. 23. 
Pachvcheles rudis Stimpson 

Pachycheles rudis Stimpson, 1858: 228 (nom. nud): 1859: 76, pi. 1 fi_g. 5. Haig, 1960: 133, 170, pi. 34 fig. 

1. Range: Alaska to southwest Baja California. Punta San Bartolome; Bahi'a Magdalena (Haig). 
Pachycheles holosericus Schmitt. See p. 23 . 

Euceramus transversilineatus (Lockington) 

Porcellana transversilineata Lockington, 1878: 396, 405. Euceramus transversilineatus: Glassell; 1938: 426, 

pi. 30. Haig, 1960: 188, 190, pi. 36 fig. 2, text-fig. 7(2). Range: Northern Golfo de California to Panama. 

BahTa de Santa Maria; BahTa Magdalena (Haig). 
Porcellana cancrisocialis Glassell. See p. 23 . 
Porcellana paguriconviva Glassell. See p.24 . 
Pisidia magdalenensis (Glassell). See p.24 . 
Megalobrachium garthi Haig. See p.24 . 
Megalobrachium erosum (Glassell) 

Pisosoma erosa Glassell, 1936: 289. Megalobrachium erosum: Haig, 1960: 213, 222, pi. 16 fig. 8, pi. 40 fig. 

2. Range: Golfo de California and southwest Baja California. Punta Malarrimo; Bahfa de San Juanico 
(Haig). Bahfa Magdalena (Glassell). 

Megalobrachium tuberculipes (Lockington). See p. 24. 
Polvonvx quadriungulatus Glassell 

' Polyonyx quadriungulatus Glassell, 1935: 93, pi. 9. Haig, 1960: 233, 236, pi. 41 fig. 2, text-fig. 12(1). 
Range: Southern California to southwest Baja California. Punta San Eugenio (Haig). 



1970 HAIG. HOPKINS AND SCANLAND: ANOMURAN CRABS 27 

KEYS TO ANOMURAN CRABS KNOWN FROM 
SOUTHWESTERN BAJA CALIFORNIA, MEXICO 

Identifications made with these keys should be considered tentative until sp)ecimens can be checked against 
descriptions and illustrations. The two sand crabs falling within the scope of our report were dealt with by Schmitt 
( 1 92 1 ). The hermit crabs of the eastern Pacific are currently being revised, but published information available at 
this writing is widely scattered and in some cases inadequate; a number of references are given in the preceding 
sections of this paper. For the Galatheidae, Pleuroncodes planipes was treated by Schmitt (1921), and 
descriptions and illustrations of the remaining species are found in either Faxon (1895) or Benedict (1902). The 
eastern Pacific Porcellanidae were monographed recently by Haig (1960). 

Sand Crabs 

la. Carapace suboval; first pair of legs simple: HIPPIDAE Emeritaanaloga 

lb. Carapace subquadrangular: first pair of legs subchelate: ALBUNEIDAE Lepidopa myops 

Hermit Crabs 
la. Antennular peduncles several times length of eyestalks; antennular flagellum compressed and truncated 

at tip: COENOBITIDAE Coenobita compressus 

lb. Antennular peduncle less than twice length of eyestalks; antennular flagellum ending in a filament 2 

2a. Outer maxillipeds approximated at their bases; chelipeds equal or subequal in size, or left cheliped larger 

than right (in Petrochirus. right larger than left): DIOGENIDAE 3 

2b. Outer maxillipeds widely separated at their bases; right cheliped always larger than left: PAGURIDAE 15 

3a. Chelipeds markedly unequal in size and form 4 

3b. Chelipeds equal or subequal in size and form 6 

4a. Right cheliped larger than left Petrochirus californiensis 

4b. Left cheliped larger than right 5 

5a. Major chela smooth; fingertips calcareous Calcinus californiensis 

5b. Major chela tuberculate; fingertips corneous and dark Dardanus sinistripes 

6a. No paired abdominal appendages in either sex 7 

6b. Paired pleopods present on first and second abdominal segments of male, and usually on first ab- 
dominal segment of female 10 

7a. Fingertips acuminate; antennal flagella heavily setose Isocheles sp. 

7b. Fingertips spooned or hoof-shaped; antennal flagella nude or sparsely setose 8 

8a. Chelipedsand walking legs with strong, grooved rings Aniculus elegans 

8b. No such rings on legs 9 

9a. Fingers open horizontally; no white spots on chelae; walking legs with longitudinal dark and light 

stripes Clibanarius panamensis 

9b. Fingers open obliquely; chelae and walking legs with large white spots Trizopagurus magnificus 

10a. Fingertips acuminate; rostrum scarcely developed, broadly rounded; 

no paired pleopods in females Paguristes. undescribed sp. 

10b. Fingertips spooned; rostrum a well-developed, acute projection; females with a pair of pleopods 11 

1 la. Rostrum long, acuminate, extending well'betweeneyescales 12 

lib. Rostrum broad, well-produced but falling short of or barely reaching base of eyescales 13 

12a. Chelaenarrow, covered with dense tomentum; eyestalks and antennae blue Paguristes anahuacus 

12b. Chelae very broad, not tomentose; eyestalks and antennae not blue Paguristes digueti 

1 3a. Eyescales with margins entire; in adults, spines on chelipeds 

not densely pigmented Paguristes praedator 

13b. Eyescales toothed; in adults, spines on chelipeds densely pigmented 14 

14a. Antennal flagellum with very long hairs on lower surface; rostrum extending beyond lateral frontal 

lobes Paguristes ulreyi 

14b. Antennal flagellum with short hairs on lower surface; rostrum about equal in length to lateral frontal 

lobes Paguristes bakeri 

1 5a. Major chela narrow, not forming an operculum; no paired pleopods in female 16 

15b. Major chela broad, forming an operculum; female with a pair of pleopods 21 

1 6a. Eyescales with 2 or more spines 17 

1 6b. Eyescales with a single spine 18 

17a. Tip ofeyescale rounded and bearing 2 or 3 spines Pagurus, undescribed sp. 

1 7b. Tip ofeyescale truncate and bearing 4 spines Pagurus lepidus 

18a. Carapaceshield wider than long; eyestalks greatly expanded distally 19 

1 8b. Carapace shield longer than w ide; eyestalks not greatly expanded distally 20 



28 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

19a. Major chela granulate on outer margin, about 2'/2-3 times as long as wide, narrower than carpus 

except at base of fingers Pagurus gladius 

19b. Major chela with sharp teeth on outer margin, about twice as long as wide and about as wide 

as carpus Pagurus smithi 

20a. Major chela with a thick fringe of hairs on margins, its dorsal surface 

tomentose and spiny Pagurus galapagensis 

20b. Major chela not hairy, its dorsal surface granulose Pagurus samuelis 

21a. Inner margin of major chela not expanded; no longitudinal ridge on 

movable finger Pylopagurus roseus 

21b. Inner margin ofmajor chela usually expanded laterally; movable finger with a longitudinal ridge 22 

22a. Carpus ofmajor cheliped nearly smooth; walking legs with longitudinal stripes overlying diffuse broad 

bands Pylopagurus californiensis 

22b. Carpus of major cheliped with small, forward-directed spines covering its dorsal surface; walking legs 

with broad bands whose margins are sinuous and sharply defined Pylopagurus venustus 

Galatheid Crabs 
la. Sides of carapace greatly swollen and visible in dorsal view; chelipeds and walking legs with a thick 

fringeoflong, fine hairs on margins. Often pelagic Pleuroncodes planipes 

lb. Sides of carapace not visible in dorsal view; no thick fringe of hairs on chelipeds and walking legs. 

Bottom living 2 

2a. Second, third, and fourth segments ofabdomen armed with spines Munida tenella 

2b. Abdomen unarmed 3 

3a. Fingers about as long as, or shorter than palm; rostrum with several lateral spines near 

its apex Munida refulgens 

3b. Fingers much longer than palm; rostrum without spines at apex Munida mexicana 

Porcelain Crabs 

la. Carapace nearly or quite half again as long as broad 2 

1 b. Carapace scarcely or not at all longer than broad 3 

2a. Carapace and chelipeds nearly smooth, without hairs; lateral margins of carapace with a series of about 

12-15 minute, close-set spinules Orthochelapumila 

2b. Carapace and chelipeds rugose, with long, scattered hairs; no marginal spinules on carapace posterior 

toepibranchial spine Euceramus transversilineatus 

3a. Movable segments of antennal peduncle with free access to orbit 4 

3b. Movable segments ofantennal peduncle separated from orbit by a broad projection of basal segment. ... 17 

4a. Side walls ofcarapace entire; chelipeds flattened, subequal 5 

4b. Posterior portion of side walls of carapace separated by membranous interspace from anterior portion; 

chelipedsthick,robust, one distinctly larger than the other 12 

5a. Carapace with transverse striations; a row ofspines on anterior margin of merus of walking legs 6 

5b. Carapace not transversely striate; anterior margin of merus of walking legs unarmed 7 

6a. Carapace with groups of spines on dorsal surface, and a row of spines on lateral margins posterior to 

epibranchial spine Petrolisthes sanfelipensis 

6b. No spines on dorsal surface ofcarapace, nor on lateral margins posterior to 

epibranchial spine Petrolisthes edwardsii 

7a. Carpus ofchelipeds armed on anterior margin with strong teeth or tubercles 8 

7b. Carpus not armed with strong teeth or tubercles 10 

8a. Carpus ofchelipeds with wide-set conical tubercles on anterior margin; chela with a thick fringe of hair 

on outer margin Petrolisthes hirtipes 

8b. Carpus with strong teeth on anterior margin; chela without a thick fringe of hairs 9 

9a. Telson5-plated; outer orbital angle produced into a distinct tooth Petrolisthes hians 

9b. Telson 7-plated; outer orbital angle not strongly produced Petrolisthes crenulatus 

10a. Carpus ofcheliped about twice as long as wide, a lobe occupying proximal '/4 of 

its anterior margin Petrolisthes cabrilloi 

10b. Carpus more than twice as long as wide, its margins subparallel 11 

1 la. Carapace nearly smooth posteriorly, often granular anteriorly; merus of walking legs with a fringe of 

hairs on anterior margin Petrolisthes manimaculis 

lib. Carapace nearly smooth anteriorly as well as posteriorly; merus of walking legs nude or with only 

traces of hair Petrolisthes gracilis 

1 2a. Front with a distinct tuft of hairs 13 

1 2b. Hairs sometimes present on frontal area, but not forming a distinct tuft 16 



1970 HAIG, HOPKINS AND SCANLAND: ANOMURAN CRABS 29 

13a. Manus with a large granulate protuberance at base of pollex; telson 5-plated in both sexes; males with 

apairofpleopods;chelipedswitheither long, scattered hairs or short, close-set hairs 14 

1 3b. No distinct protuberance on manus at base of pollex; telson 7-plated in males, 7- or 5-plated in females; 

male pleopods present or absent; chelipeds with both long, scattered hairs and short, close-set hairs 15 

14a. Carpus of chelipeds with a broad triangular lobe; chelipeds with long, 

scattered hairs Pachycheles rudis 

1 4b. Carpus with a broad, serrate -edged lobe; chelipeds with short, close-set hairs . . Pachycheles holosericus 
1 5a. Carpus of chelipeds with a broad lobe cut into 3 or 4 uneven, serrate teeth; males with a 

pair of pleopods Pachycheles pubescens 

15b. Carpusarmed with 3 (rarely 4) spine-tipped teeth; no pleopods in males Pachycheles spinidactylus 

1 6a. Carpus of chelipeds with 2 broad teeth; telson 7-plated; males with a 

pair of pleopods Pachycheles panamensis 

16b. Carpus with 3-5 narrow teeth; telson 5-plated; no pleopods in males Pachycheles marcortezensis 

17a. Carapace broader than long; dactyl ofwalking legs with 4 fixed spines Polyonyx quadriungulatus 

17b. Carapace not broader than long; dactyl ofwalking legs with a single terminal claw and several movable 

spinules 18 

18a. Front prominent, strongly tridentate or trilobate in dorsal view 19 

' 18b. Front deflexed, appearing rounded or faintly trilobate in dorsal view 21 

19a. Lateral margins ofcarapace unarmed posterior to epibranchial angle 20 

19b. Lateral margins ofcarapace with minute spinules Pisidia magdalenensis 

20a. Epibranchial angle with 2 or 3 spinules; frontal teeth pointed at tips Porcellana cancrisocialis 

20b. Epibranchial angle unarmed; frontal teeth rounded at tips Porcellana paguriconviva 

21a. Telson of abdomen 7-plated Megalobrachium erosum 

21b. Telson 5-plated 22 

22a. Carapace,chelipeds, and walking legs covered with small, shallow pits Megalobrachium garthi 

22b. Carapace,chelipeds, and walking legs tuberculate Megalobrachium tuberculipes 

REFERENCES 

Benedict, J. E. 

1892. Preliminary descriptions of thirty-seven new species of hermit crabs of the genus Eupagurus in the 
U.S. National Museum. Proc. U.S. Natl. Mus. 15: 1-26. 

1902. Descriptions of a new genus and forty-six new sf)ecies of crustaceans of the family Galatheidae, with a 
list of the known marine species. Proc. U.S. Natl. Mus. 26: 243-334. 
Boone, L. 

1931. A collection of anomuran and macruran Crustacea from the Bay of Panama and the fresh waters of 
the Canal Zone. Bull. Amer. Mus. Nat. Hist. 63: 137-189. 

1932. The littoral crustacean fauna of the Galapagos Islands. Par II. Anomura. Zoologica 14: 1-62. 
Bouvier, E. L. 

1893. Paguriens recueillis par M. Diguet, sur le littoral de la Basse-Californie. Bull. Soc. Philom. Paris, Ser. 
8,5: 18-25. 

1895. Sur une collection de crustaces decapodes recueillis en Basse-Californie par M. Diguet. Bull. Mus. 

Hist. Nat., Paris 1:6-8. 
1898. Sur quelques crustaces anomoures et brachyures recueillis par M. Diguet en Basse-Californie. Bull. 

Mus. Hist. Nat., Paris 4: 371-384. 
Chace, F. A.. Jr. 

1962. The non-brachyuran decapod crustaceans of Clipperton Island. Proc. U.S. Natl. Mus. 1 13: 605-635. 
Faxon, W. 

1893. Reports on the dredging of)erations off the west coast of Central America to the Galapagos, to the 

west coast of Mexico, and in the Gulf of California ... by the U.S. Fish Commission Steamer 

"Albatross," during 1891 . . . VI. Preliminary descriptions of new species of Crustacea. Bull. Mus. 

Comp. Zool. 24: 149-220. 
1895. Reports on an exploration off the west coasts of Mexico, Central and South America, and off the 

Galapagos Islands ... by the U.S. Fish Commission Steamer "Albatross," during 1891 . . . XV. 

The stalk-eyed Crustacea. Mem. Mus. Comp. Zool. 18: 1-292. 
Forest, J. 

1952. Contributions a la revision des crustaces Paguridae. I. Le Genre Trizopagurus. Mem. Mus. Hist. 

Nat., Paris, Ser. A., 5(1): 1-40. 



30 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

1964. Sur un nouveau genre de Diogenidae (Crustacea Paguridea) de I'Atlantique sud-ame'ricain, Loxopa- 
gurus gen. nov., etabli pour Pagurus loxochelis Moreira. Zool. Meded. 39: 279-296. 
Forest, J., and Michele de Saint Laurent 

1968. Campagne de la Calypso au large des cotes atlantiques de rAmerique du Sud (1961-1962). 6. 
Crustace's de'capodes: Pagurides. Ann. Inst. Oce'an.45: 47-170. 

Glassell, S. A. 

1935. New or little known crabs from the Pacific Coast of northern Mexico. Trans. San Diego Soc. Nat. 
Hist. 8:91-106. 

1936. New porcellanids and pinnotherids from tropical North American waters. Trans. San Diego Soc. Nat. 
Hist. 8:277-304. 

1937a. The Tempieton Crocker Expedition. IV. Porcellanid crabs from the Gulf of California. Zoologica 22: 

79-88. 
1937b. The Tempieton Crocker Expedition. XI. Hermit crabs from the Gulf of California and the west coast 

of Lower California. Zoologica 22: 241-263. 

1938. New and obscure decapod Crustacea from the west American coasts. Trans. San Diego Soc. Nat. 
Hist. 8:411-454. 

1945. Four new species of North American crabs of the genus Petrolisthes. J. Wash. Acad. Sci. 35: 223-229. 
Haig,J. 

1957. Four new porcellain crabs from the eastern Pacific. Bull. S. Calif. Acad. Sci. 56: 31-41. 

1960. The Porcellanidae (Crustacea Anomura) of the Eastern Pacific. Allan Hancock Pac. Exped. 24: 1- 
440. 

1962. Papers from Dr. Th. Mortensen's Pacific expedition 1914-1916. LXXIX. Porcellanid crabs from 
eastern and western America. Vidensk. Meddel. Dansk Naturhist. Foren. Kjobenhavn 124: 171-192. 
Holmes, S. J. 

1900. Synopsis of California stalk-eyed Crustacea. Occ. Pap. Calif. Acad. Sci. 7: 1-262. 
Holthuis, L. B. 

1954. On a collection of decapod Crustacea from the Republic of El Salvador (Central America). Zool. 
Verhandel.,Leiden 23: 1-43. 

Lockington, W. N. 

1 878. Remarks upon the Porcellanidea of the West Coast of North America. Ann. Mag. Nat. Hist., Ser. 5, 
2: 394-406. 

Matthews, L. H. 

1932. Lobster-krill, anomuran Crustacea that are the food of whales. Discovery Rept. 5: 467-484. 

Milne Edwards^H. 

1837. Histoire Naturelle des Crustaces, Comprenant 1" Anatomic, la Physiologic et la Classification de Ces 
Animaux. Vol. 2. Paris. 

Nininger, H. H. 

1918. Crabs taken at Laguna Beach in the summer of 1916. J. Ent. Zool. 10: 36-42. 

Nobili,G. 

1901. Viaggio del Dr. Enrico Festa nella Repubblica dell'Ecuador e regioni vicine. XXIII. Decapodi e 
stomatopodi. Boll. Mus. Zool. Anat. Comp. Torino 16 (415): 1-58. 

Parker, R. H. 

1964. Zoogeography and ecology of some macro-invertebrates, particularly mollusks, in the Gulf of 
California and the continental slope off Mexico. Vidensk. Meddel. Dansk Naturhist. Foren. 
Kjobenhavn 126: 1-178. 

Radovich, J. 

1961. Relationships of some marine organisms of the northeast Pacific to water temperatures particularly 
during 1957 through 1959. Fish Bull. 112. Calif. Dept. Fish and Game. 

Rathbun, M. J. 

1910. The stalk-eyed Crustacea of Peru and the adjacent coast. Proc. U.S. Natl. Mus. 38: 531-620. 

Ricketts, E. F., and J. Calvin 

1939. Between Pacific Tides. Stanford University Press, Palo Alto, Calif. 

Saussure. H. de 

1853. Description de quelques crustace's nouveaux de la cote occidentale du Mexique. Rev. Mag. Zool., Ser. 
2,5:354-368. 
Scanland, T., and T. Hopkins 



1970 HAIG. HOPKINS AND SCANLAND: ANOMURAN CRABS 31 

1969. A new species of hermit crab, Pylopagurus diegensis (Decapoda: Anomura), with a key for the genus 
in the Eastern Pacific. Pac. Sci. 23 (2): 257-260. 

Schmitt, W. L. 

1921. The marine decapod Crustacea of California. Univ. Calif. Pubi. Zooi. 23: 1-470. 

1935. Crustacea Macrura and Anomura of Porto Rico and the Virgin Islands. Sci. Surv. Puerto Rico 15: 

125-227. 
1939. Decapod and other Crustacea collected on the Presidental Cruise of 1938 (with introduction and 

station data). Smithsonian Misc. Coll. 98 (6): 1-29. 
Steinbeck, J., and E. F. Ricketts 

1941. Sea Cortez, a Leisurely Journal of Travel and Research, with a Scientific Appendix Comprising 

Materials for a Source Book on the Marine Animals of the Panamic Faunal Province. Viking Press, 

New York. 

Stimpson, W. 

1857. Notices of new species of Crustacea of western North America; being an abstract from a paper to be 
published in the Journal of the Society. Proc. Boston Soc. Nat. Hist. 6: 84-89. 

1858. Prodromus descriptionis animalium evertebratorum . . . Pars VII. Crustacea Anomura. Proc. Acad. 
, Nat. Sci. Philadelphia 10: 225-252. 

1859. Notes on North American Crustacea, No. 1. Ann. Lye. Nat. Hist., N.Y. 7: 49-93. 

1860. Notes on North American Crustacea, in the Museum of the Smithsonian Institution. No. II. Ann. Lye. 
Nat. Hist., N.Y. 7: 176-246. 

Walton, B. C. 

1954. The genus Pylopagurus (Crustacea: Anomura) in the Pacific with descriptions of two new species. 
Allan Hancock Pac. Exped. 18: 139-173. 



Allan Hancock Foundation, University of Southern California, Los Angeles, Califor- 
nia 90007 (JH), and University of California San Diego, Scripps Institution of Oceanogra- 
phy, LaJolla, California 92037 (TSH and TBS). 

Present address of TSH: Faculty of Biology, University of West Florida, Pensacola, 
Florida 32504. 




COMPARATIVE BIOLOGY OF AMERICAN 
BLACK WIDOW SPIDERS 



B. J. KASTON 



MUS. COMP. ZOOL. 
LIBRARY 

DEC 3 "1972 

HARVARD 
UNIVERSITY 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



Vol. 16, No. 3 24 July 1970 



COMPARATIVE BIOLOGY OF AMERICAN 
BLACK WIDOW SPIDERS 



B. J. KASTON 



ABSTRACT. — There are three American species of black widow spiders: Latrodcctiis mactans 
and L. variohis in the eastern U.S., and only L. Iiespenis in the western. Although there is much 
variation within each species, and to an extent some overlap, they differ in several ways. The egg 
sac in L. hesperiis is tan and pyriform. in L. variohis gray and pyriform, and in L. mactans gray 
and spherical. Latrodectiis mactans averages fewer egg sacs per female than L. hesperiis. but 
more eggs per sac; L. variohis averages the smallest number per sac. The eggs and newly emerged 
spiderlings are smallest in L. mactans. and largest in L. variohis: those of L. variolas hatch and 
emerge in the shortest, of L. hesperiis in the longest time. 

Newly emerged spiderlings of each species are characteristically marked, but as they ap- 
proach maturity they become more alike, especially the females. Mature males are more easily 
distinguished by their pattern. Red and white marks on the dorsum of mature females tend to be 
most prominent in L. variohis (and the texaniis variety of L. hesperiis) less in L. mactans. and 
least or even absent in L. hesperiis. The hour-glass mark is always divided in L. variolas, and 
generally complete in the others. Latrodectiis variohis takes longest to mature; L. mactans is 
quickest, and also is shortest lived. 

In all three species the spiderlings usually rtoh only once, occasionally twice, and rarely 
more times before emergence from the sac. The sexual behavior is similar, and in each a portion 
of the embolus is left behind in the female genitalia after copulation. The palpal organ of L. hes- 
periis is more like that of L. variolas generally; but because of the extreme variation, it is not 
always possible to separate L. hesperiis and L. mactans by embolus coil morphology. The inter- 
vals between successive ovipositions and the proportion of eggs that develop from successive egg 
sacs show no trend toward increasing, or decreasing, and are highly variable in any series. 

RESUMEN. — En America existen tres especies de aranas viudas negras: Latrodectus mactans 
y L. variohis en la region oriental de los Estados Unidos, y L. Iiespenis en el Oeste. Aun cuando 
cada especie presenta gran variabilidad en sus caracteres morfologicos y algunos de ellos son 
comunes, en cierto grado, a varias especies, es posible diferenciarlas facilmente. En L. hesperiis 
el saco ovigero es piriforme y de color marron, en L. variohis es tambien piriforme pero de color 
gris, y en L. mactans es gris y esferico. Las hembras de Latrodectus mactans presentan en general 
menos sacos ovigeros y mas huevos en cada saco que en L. Iiespenis; mientras que en L. variohis 
el niimero de huevos por saco es menor. Los huevos y las aranitas racien nacidas son de talla 
menor en L. mactans, y mayores en L. variolas. Las crias de L. variolas tardan menos tiempo 
en nacer, mientras que en L. hesperiis la incubacion dura mas tiempo. 

Las araiias racien nacidas correspondientes a estas tres especies presentan caracteres diferen- 
tes y bien marcados; pero tales diferencias van reduciendose progresivamente a medida que 
alcanzan la madurez, llegando entonces a ser tan similares que resulta dificil diferenciarlas, par- 
ticularmente tratandose de las hembras. Los machos maduros son sin embargo mas faciles de 
identificar, considerando el diseiio particular que presentan. Las marcas rojas y blancas que 
aparecen en el dorso de las hembras maduras tienden a ser mas prominentes en L. variolas (y en 
la variedad te.xaniis de L. Iiespenis) y menos marcadas en L. mactans. y en L. hesperiis esas mar- 
cas se desvanecen hasta llegar a desaparecer. La marca en forma de reloj de arena aparece di- 
vidida en L. variolas, mientras que en las otras especies esta completa. Latrodectus variolas es 
la especie que tarda mas en alcanzar la madurez, y L. mactan madura pronto ye es de vida corta. 

Las aranitas de estas tres especies pasan, antes de salir del saco, por una sola muda, a veces 
dos y raramente sufren una tercera muda. El comportamiento sexual es similar en estas tres 

SAN DIEGO SOC. NAT HIST, TRANS. 16(3): 33-82, 24 JULY 1970 



34 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

especies, y en todas ellas el emholo queda en las genitales de la hembra despues de la copula. 
El organo palpal de L. hespcnis es similar al de L. varioliis; pero debido a la extremada varia- 
bilidad que presentan los individuos. resulta a veces dificil separar a L. hespenis de L. mactiis 
basandose en la morfologia del rizo del embolo. Los intervalos entre Duestas sucesivas de huevos 
y la proporcion de huevos que se desarrollan en las series de sacos ovigeros no presentan ninguna 
tendencia particular, ya sea en sentido progresivo o regresivo, variando extremadamente su 
niimero en cualquiera de estas especies. 

Because of the potency of their venom against man, spiders of the genus Latrodectus 
are of great importance medically. As a result of the interest generated during protracted 
periods in which cases of envenomation were being regularly reported, and specimens were 
being collected by many people, several life history studies were made during the 1930's 
and 1940's. The taxonomic study by Levi (1958, 1959) stimulated a renewed interest, which 
has continued to the present. 

Pickard-Cambridge (1902) published a revision of the genus, in which he considerably 
reduced the number of valid species. He maintained as distinct however, L. curacaviensis 
(MuUer) of the New World, which he separated from L. mactans in part on the basis of the 
hourglass mark being different in form. Nearly all later workers generally assumed that the 
spider which is most commonly called the ''black widow" represented a single, but highly 
variable, species, L. mactans. and the list of its synonyms is long (see Petrunkevitch, 191 1; 
Roewer, 1942; Bonnet, 1957). Thus much of the available information on life history, 
variation, and so forth, reported for this latter species was "contaminated," being ap- 
plicable, in part, to the now recognized related species. 

Levi (1958, 1959) not only maintained L. curacaviensis but considered that it was the 
species which is widely distributed over the northern and western United States and 
Canada, with L. mactans in the southern States. Levi also discussed the hourglass mark 
and general pattern of spots, and especially noted instances where both species were 
completely devoid of such markings. In 1964, with McCrone, he showed that the "brown 
widow," L. geometricus C. L. Koch, and the "red widow," L. bishopi Kaston, appear to be 
limited to southern Florida. Also, of the two species of "black widow," L. mactans is more 
common in southern, and another species more common in the northern States and 
Canadian Provinces. The species which he had previously identified as the West Indian L. 
curacaviensis, was in reality L. variolus. The distribution of L. mactans and L. variolus 
overlaps, and although in my previous work (1937a, 1937b, 1938, 1948, 1953, 1954) I had 
used only the name L. mactans, it is known that both species occur in the southern New 
England area, with L. variolus the more common of the two. 

McCrone and Levi published some notes on the life history of the Florida populations 
of L. mactans and L. variolus. which are sympatric there. They indicated that the same two 
species also occur in California and other western States. Shortly afterwards I began my 
observations on the post-embryonic development of our California black widow. At the 
same time I was also observing the development of a family of L. mactans from Florida. In 
noting the differences, particularly in the appearance of the spiderlings, I assumed that my 
California specimens, which did not look like the Florida L. mactans, must be L. variolus. 
But I found certain discrepancies between my results and those reported for L. variolus by 
McCrone and Levi. In addition, there appeared to be some morphological differences from 
those specimens of L. variolus which Dr. McCrone was kind enough to have sent me from 
Florida, and from those specimens collected by me years ago in Connecticut. As additional 
material became available it became apparent that neither L. mactans nor L. variolus 
occurs in the west, and that yet another species, L. Hesperus, is represented (Kaston, 1968). 
It is my primary aim to compare the biology of this western species with that of the true L. 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 35 

mactans, but some comparisons are made with L. variolus as well. 

Each of these species is variable so that if one sees enough specimens one encounters 
the variations noted by Parrott (1946) with the ctenid, Uliodon piscator. and by MuUer 
(1952) with the agelenid, Coelotes atropos. These variations can be morphological, both 
exophenotypic and endophenotypic, as well as ethological. And at times they overlap with 
the characters shown by one or both of the other two species, so that even with a specimen 
in hand one may not be certain to which species it belongs. 

While most of the information presented is based upon studies since 1965, some data 
were collected in Georgia, in North Carolina, and in Connecticut over many years previous 
to 1964. 

MATERIALS AND METHODS 

Specimens were collected from various areas, the majority from California and hence 
mostly L. hesperus. But many live specimens of L. mactans were sent from eastern and 
southern States by cooperative workers. Likewise, a relatively small number of £. variolus 
were obtained. For the most part mature females were received, but a number of males, 
and some half grown individuals, were likewise obtained. 

From the egg sacs produced by these female spiders I set out for L. hesperus 29 
families (ca. 2600 spiderlings); 18 from California, four from Texas, four from British 
Columbia, and one each from Arizona, Oregon, and Baja California; for L. mactans 37 
families (ca. 2800 spiderlings): nine from New York, four each from Virginia and 
Arkansas, three each from Florida and Illinois, two each from Missouri, New Jersey, 
North Carolina and Ohio, and one each from Alabama, Louisiana, Mississippi, Oklahoma 
and Tennessee; and for L. variolus 12 families (ca. 900 spiderlings) seven from Missouri, 
three from Michigan, and one each from Arkansas and Florida. I received the L. variolus 
material late in my study, and unfortunately, because of factors as yet not understood, I 
had little success in rearing these latter spiderlings to maturity. Live specimens were also 
received from the following areas: Alberta, Georgia, Kansas, Washington and West 
Virginia. 

Many of the mature specimens were used in studies on the chemical nature of the 
hemolymph (as in McCrone, 1968); many of the males were sacrificed before maturity for 
studies on the chromosomes. The results of both these studies are being published 
elsewhere. 

In the laboratory each spider was placed in its own glass container. When egg sacs 
were m.ade they were removed and each placed in a vial and given a code number. Thus the 
first sac made by female #1052 was #1052-A, the second was #1052-B, the third was 
#1052-C, etc. Those used for the study of development and/or for the rearing of 
spiderlings were kept in a constant temperature room at 25° C. 

When the spiderlings emerged, each was placed in its own labelled vial, and given its 
own number, e.g., #1052-A-1, #1052-A-2, etc. When the spiderling became larger it was 
transferred to a larger container. The containers were stoppered with polyurethane foam. 
All specimens were checked and data taken daily. After the spiders matured they were 
removed from the constant temperature room and kept in one of the laboratories at room 
temperature. 

In the early years of this study the spiderlings were fed entirely on fruit flies, 
Drosophila melanogaster. Although some males matured (in the fourth and fifth instars), 
the females did not. Apparently nutritional deficiency was involved, possibly an insufficient 
supply of one of the essential amino acids. Comparable findings were later reported by 
Miyashita (1968) in his attempts to raise specimens of Lycosa. However, when older 



36 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 






Figure 1. a. Female Latrodectus in the normal position hanging in her web; b, Latrodectus mating position; the 
female is represented in outline and the male is blackened; c, the venom glands as seen from above in relation to 
the entire cephalothorax; d, the left venom gland with its duct, and left chelicera. 

spiderlings, as well as the adults, were fed on mealworms, Tenebrio molitor, and other 
insects that could be obtained outdoors, chiefly blue bottle and other muscoid flies, many 
reached maturity. 

DESCRIPTION OF ADULTS 

The genus Latrodectus Walckenaer, 1805, is cosmopolitan. It comprises medium- 
sized spiders, which are the largest members of the Family Theridiidae, those spiders 
bearing a comb of serrated bristles along the ventral surface of tarsus IV. This comb is well 
developed, and quite conspicuous in Latrodectus. The lateral eyes of each side are widely 
separated, generally a diameter or more apart. The colulus is large and distinct, and the 
legs are moderately long, with the first usually longer than the fourth, and the third 
shortest. In females the abdomen is usually relatively large, high and subglobose. The 
venom glands are large and extend far back into the cephalothorax (Figs. Ic and Id). 
Males are much smaller than females, have relatively longer legs, and have the abdomen 
lower and narrower, so that it appears somewhat ellipsoidal. Males are also commonly 
more brightly colored. The webs made by these spiders are irregular meshes in which the 
spider stands in an inverted position (Fig. la). Three species occur in the United States, all 
quite variable in markings and color pattern. The descriptions and illustrations here 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 37 

supplied represent the colors and patterns commonly met with. 

Latrodectus mactam (Fabricius) 
Figs. 2, 3, 4a, 4c, 5c, 12, 13a-d, g, i, k 

Aranea mactans Fabricius, 1775, Systema Entomologiae, etc. p. 492 (no. 4); Fabricius, 1793, Entomologiae 

Systematica, etc., p. 410 (No. 1 1) (exact copy of 1775). 
Latrodectus mactans mactans: Chamberlin and Ivie, 1935, Bull. Univ. Utah, 25(8): Biol. Ser., 3(1): 13. 
Latrodectus mactans: Kaston, 1948. Connecticut Geol. and Nat. Hist. Surv. Bull. 70: 92 (in part); Levi, 1959, 

Trans. American Microscop. Soc, 78:24 (in part). 

Levi indicated (1959: 16) that Chamberlin and Ivie gave Massachusetts as the type 
locality for L. mactans, and added "where L. mactans has now been found not to occur." 
Levi implied that Massachusetts could not have been the type locality as he had not seen 
specimens from there. Yet this species may well be found in Massachusetts, most probably 
along the southern shores and nearby islands in the Cape Cod region. After all, L. mactans 
is known from Connecticut, and I have seen numerous specimens from the part of New 
York (Westchester County) bordering on Long Island Sound, a region hardly 25 miles 
farther south than the southernmost part of Massachusetts. One can no more assume that 
Massachusetts is not the type locality for L. mactans merely because Levi has not found 
any there, any more than we can assume that the island of Cura9ao is not the type locality 
for L. curacaviensis because he was unable to find even a single individual when he visited 
that island especially to search for specimens (McCrone and Levi, 1964)! It is true, 
however, that one would hardly have expected L. mactans to be common enough in 
Massachusetts for this to be where Fabricius' specimen came from. Many years ago I 
wrote Professor Chamberlin about this. In his answering letter he stated, ''Massachusetts 
is given as type locality on the basis of the statement by Fabricius himself." Yet in both of 
the references cited above I found Fabricius to state only "In America Dom. Lewin," so 
that I must agree with Levi that the type locality was "incorrectly stated" in the paper by 
Chamberlin and Ivie (1935). Levi considers that the type may have come from the 
southeastern United States, or the West Indies. 

This is the common species of our southeastern States, but has been found as far north 
as southern New York, and southern New England, west through southern Ohio, Indiana, 
Illinois, Missouri, to about central Kansas, and south through central Oklahoma and 
Texas. 

In the female the cephalothorax and legs are shiny black, usually unmarked. The 
abdomen is black with the following markings in red. On the venter is the characteristic 
hourglass mark, usually consisting of an anterior triangle, and a generally wider posterior 
rectangle with rounded corners. 

There is much variation, and even in the same individual the markings, including the 
hourglass, may at times be more distinct, and at other times be less distinct. Some of the 
shapes taken by the hourglass are shown in figure 3. McCrone and Levi (1964) suggested 
that the more brightly colored specimens had undergone fewer molts, as I had formerly 
supposed. But as indicated above, the evidence seems not to bear this out. Gerschman and 
Schiapelli (1943) illustrated a variety of patterns for Argentine specimens, and I find it 
significant that they found no correlation between body size and type of pattern. Possibly 
they were dealing with more than one species; at any rate Abalos and Baez (1967) and 
Pinter (1968) published figures showing the variations present in what they considered to 
be four species additional to L. mactans. Along the mid-dorsal line is a row of spots, the 
most anterior of which may appear as a short chevron. 

Generally, the male is similar to a fifth instar female. The cephalothorax may be all 



38 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 










Figure 2. Latrodeclus mactans. a, dorsal aspect of female from Florida; b, ventral aspect of same female; c, 
epigynum of same female from below; d, dorsal aspect of male from Florida; e, ventral aspect of same specimen; 
f, lateral aspect of male from Louisiana; g, dorsal aspect of cleared epigynum of female from New York. 

black, or the carapace may show a somewhat lighter band on either side of a median black 
band. The legs may be all black (Fig. 5c), or have lighter annuli (Fig. 4c) retained from 
earlier instars. There is a median row of red spots on the dorsum of the abdomen. On the 
venter the hourglass mark is distinct. Encircling the anterior end of the abdomen is a white 
band, and on either side farther back are two additional white bands which extend 
diagonally down and to the rear. Seen from the side this gives the appearance of three 
white bands (Fig. 20- In L. Hesperus there are also three white bands as seen from the side, 
but the anterior one is always hooked and procurved near its ventral end, while this is 
uncommon in L. mactans. Also, in L. Hesperus the background color is much lighter. In L. 
variolus the ground color is as dark as in L. mactans. and there are four bands visible along 
the side. 



Latrodectus variolus Walckenaer 
Figs. 4b, 5a, 6a-f, 7, 14a, b, f 

Latrodectus variolus Walckenaer, 1837, Hist. Nat. Insectes Apteres, 1:648. 

Latrodectus mactans: Emerton, 1902, Common Spiders of the United States, (in part) fig. 291(j'; Kaston, 1948 

Connecticut Geol. Nat. Hist. Surv. Bull. 70;92 (for the most part). 
Latrodectus curacaviensis: Levi, 1959, Trans American Microscop. Soc, 78:38 (in part). 
Latrodectus variolus: McCrone and Levi, 1964, Psyche 71:13 



1970 



KASTON: AMERICAN BLACK WIDOW SPIDERS 



39 











Figure 3. Ventral aspect of abdomens of L. maclans females to show variation in the shape of the hourglass 
mark, and in the epigynal orifice, a, from Arkansas; b, from New York; c, From New York; d, from Tennessee; e, 
from North Carolina; f, from Virginia; g, from New York; h, from New York. 

While most workers seem to consider this species distinct from L. mactans. 
Gerschman and SchiapeUi (1965) continue to place L. curacaviensis (and presumably also 
L. variolas) as a synonym of L. mactans. 

This species occurs in the United States in about the same areas as L. mactans, but 
apparently is much less common. However, its range extends into more northern states and 
adjacent Canadian provinces where L. mactans presumably does not occur. 

Illustrations of this species have been published recently by Judd (1965) and Wilson 
(1967). The female has the cephalothorax black, and the legs are similar, usually without 
faintly brown annuli. There is a row of middorsal red spots on the abdomen. In addition, 
there are three pairs of diagonal white stripes on each side, and a narrow white stripe 
encircling the front of the dorsum. In some specimens these stripes are yellowish to 
pinkish. The hourglass mark is divided, the two halves separated. There is much variation 
in the shape and the size of the two halves (Fig. 7), occasional specimens showing only one 
of the halves, and occasional specimens lacking the mark entirely (Kaston, 1954). The 
male has the cephalothorax and legs black as in the female, but the legs are more likely to 
show the brown annuli. The dorsum shows a pattern similar to that of the female, but with 
the white stripes generally broader. From the side four such stripes are visible (Fig. 6f) 
making this sex relatively easy to distinguish from the males of L. Hesperus and L. 
mactans. which have only three light stripes. The hourglass mark is divided. 

Latrodectus Hesperus Chamberlin and Ivie 
Figs. 5b, 8, 9, 10, 11, 13e, f, h 

Latrodectus mactans Hesperus Chamberlin and Ivie, 1935, Bull. Univ. Utah 25(8): Biol. Ser. 3 (1):15 [types from 

Salt Lake City. Utah]. 
Latrodectus mactans texanus Chamberlin and Ivie, 1935, Bull. Univ. Utah 25(8): Biol. Ser. 3(1): 14 [types from 

Texas ). 
Latrodectus mactans: Gerschman and SchiapeUi, 1943, in, Sampayo "Latrodectus mactans y Latrodectismo" (in 

part) fig, 7. 
Latrodectus curacaviensis: Levi, 1959, Trans. American Microscop. Soc. 78:38 (in part). 
Latrodectus variolus: Levi, 1969, Psyche 76:72. 



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y. -^ 



Figure 4. a, L. maclans female from Missouri showing ventral surface; b, L. variolas female from Connecticut, 
showing dorsal spots; c, L. mactans male showing annulate legs. 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 41 

This is the only species of black widow found west of about the middle of Texas, 
Oklahoma, and Kansas to the Canadian provinces. Levi has recorded both L. mactans and 
L. vaholus (sub curacaviensis) from the west but, based especially upon the appearance of 
males and spiderlings, I am unable to ascribe to either of these two species any black 
widows I have seen from the areas indicated. 

The figure 7 supplied by Gerschman and Schiapelli is an exact copy of an illustration 
from D' Amour et al. (1936) which is of a male from Colorado and quite definitely L. 
Hesperus. O'Rourke (1956) indicated that what he had seen from western Canadian 
provinces belonged to L. Hesperus. But Levi (1969) synonymized this species with L. 
variolus, presumably on the basis of the fact that the male palpal organ shows two loops of 
the embolus. 

The female has the cephalothorax and legs black. In most specimens the dorsum of 
the abdomen is likewise entirely black. In only a few is there left a remnant or the 
middorsal stripe as a small red spot just above the anal tubercle. Also, there may be, on the 
anterior portion of the abdomen, which overhangs the carapace, a remnant of the light 
transverse band, as a kind of "chevron" pointing downward. Occasionally this "chevron" 
is doubled, composed of two closely set thin lines (as in Fig. 10). 

Ordinarily the hourglass mark is complete, with a narrow connecting piece between 
the two triangular halves, and usually the base of the anterior triangle is wider than the 
base of the posterior triangle. Sometimes there is a spot of black in the center of the 
connecting piece, or the mark is divided into two parts. There is much variation, some of 
the varieties being shown in figure 9. Rarely is the middle part broad, and very rarely is the 
posterior half wider than the anterior. 

In the variety texanus the dorsum retains more of the white and red, with a central 
band, and lateral bands much like juveniles in the sixth instar (Fig. 8c). Often the white 
areas become suffused with black pigment so that older females will show only the red 
spots surrounded by black. I have this variety not only from Texas, but also from several 
localities in California. Interestingly enough, both this and the more typical variety 
sometimes were taken in the same place at the same time. 

The male has on the carapace a dark gray to black band along the lateral margins, and 
a dark band along the middle. The sternum is dark along the lateral borders, but lighter in 
the middle. The legs show dark annuli. The hourglass mark is not much constricted in the 
middle and is usually yellow rather than red, some specimens showing a slight suffusing of 
orange pigment. 

The abdominal dorsum shows a characteristic pattern of olive greenish gray 
alternating with light tan bands (Fig. 8e, 0- One of the light areas appears as a middorsal 
band usually with orange pigment as a thin line down its center. The other light areas 
appear as three bands on each side, which extend along the sides diagonally down and 
toward the rear. The most anterior of these is hooked and procurved nears its ventral end 
(Fig. 8g). The male of L. mactans also shows three bands along the side but only rarely is 
the first one hooked and procurved. In L. variolus there are four bands. Moreover, in both 
L. mactans and L. variolus the areas between these light bands are much darker than in L. 
Hesperus. In the variety texanus the gray areas, instead of being suffused with olive-green 
pigment are suffused with pink. 

COLOR VARIATIONS 

One common variation concerns the background black characteristic of most adults, 
especially the females. That the abdomen is in some individuals brownish or sepia in color, 
rather than black, was reported by Burt (1935) for Kansas specimens that were probably L. 



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.( 



% 



W"^ 



■%, 







*j 




Figure 5. a, L. variolus male; b, L. Hesperus male; c, L. mactans male, with legs devoid of annuli. 



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43 










Figure 6. Latrodectus variolus. a, female from Florida, dorsal aspect; b, ventral aspect of same female; c. female 
from Michigan, dorsal aspect of abdomen; d, female from Connecticut, dorsal aspect; e, ventral aspect of same 
female; f, lateral aspect of male; g, dorsal aspect of penultimate male. 

mactans: by Herms et al. (1935) for California specimens that were definitely L. hesperus; 
by Minton (1950) for Indiana specimens that were probably L. variolus: and by Wilson 
(1967) for Michigan specimens of the same species. As I pointed out (1968) for all three 
species, the same specimen can at times appear black, and at other times sepia or even 
lighter brown. Some specimens revert to black over a period of several months. My notes 
indicate that 111 specimens of L. hesperus turned from black to brown, and 27 turned 
black again; twenty-nine specimens of L. mactans turned brown, and 9 turned black again; 
and 8 specimens of L. variolus turned brown. I have collected both black individuals and 
brown ones of L. hesperus at Brawley, California, within a few feet of one another, where 
the ecological situations were seemingly similar. In one backyard lot the ratio of brown 
specimens to black collected was 9: 1 . 

A variation about which much has been written is the shape of the hourglass mark, 
and for each species a few examples from mature females are illustrated (Figs. 3, 7 and 9). 
Sometimes the mark disappears from a specimen which formerly showed it well; but it 
may also return slowly at a later date. 

Pattern variations formed by the red and white marks on the dorsum, have also been 
noted. It is generally considered that more of a dorsal pattern, and that larger areas of red 
and white, reflect the retention in the adult of a more juvenile pattern. Reese (1940) 



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Figure 7. Ventral aspect of abdomens of L. variolus females to show variations in the shape of epignyal orifice, 
and of hourglass mark, a, from Arkansas; b, from Missouri; c, from Michigan; d, from Missouri; e, from 
Missouri; f, from Michigan; g, from Michigan; h, from Illinois. 



illustrated some variations in shape of hourglass mark and the arrangement of dorsal 
spots. However, he may have included some juveniles, and could have confused L. variolus 
and L. mactans, both of which occur in West Virginia. Levi (1959) suggested that Reese's 
smaller ones were L. variolus. and his larger ones L. mactans. In my experience, however, 
L. variolus averages larger in size than L. mactans. Thorn (1967) gave a brief discussion of 
the variation in what is undoubtedly L. Hesperus. 

With so much variation occurring in the adult females, the three species at times are 
difficult to distinguish. But as Keegan (1955) has indicated "juvenile specimens possess 
distinctive markings even when individual adults are alike.'" It was on the basis of these 
differences (between Kansas and Michigan juveniles) that Lawson (1933) first suggested 
that we were dealing with another species besides L. mactans. This other species has since 
come to be known as L. variolus. From what is now known of the appearance of the 
spiderlings it seems obvious that the descriptions of Herms et al. (1935), D' Amour et al 
(1936), Moles (1916), Bristowe (1945, 1946) and Gonzales (1954) apply to L. hesperus; 
those of Lawson (1933), Blair (1934), Muma (1944) and Deevey (1949) apply to L. 
mactans: those of Kaston (1937b) to L. variolus. 

MEASUREMENTS 

The vernacular name "black widow" alludes to the commonly held supposition that 
the female always eats the male after mating. This idea is strengthened by the fact that 
there is a great difference in size between the two sexes. One often finds in the literature 
remarks about the female being twice, or even three times as large as the male. Of course, 
such statements are misleading, for they refer to the length of the body, as in the case of a 
male 4 mm long and a female 12 mm in length. But the female has thicker legs, and a much 
higher, globose abdomen, so that her mass may be many times more than three times that 
of the male. Most males of L. hesperus '^Q\g\\ between 8 and 18 mg; most females between 120 
and 400 mg. One small male, # 1052-C-203 with a body length of 3.5 mm weighed 5.9 mg, 
and a large gravid female, # 1 528, whose body length was 12.5 mm, weighed 944.9 mg, or 



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Figure 8. Latrodectus Hesperus, a, female from Arizona, dorsal aspect; b, lateral aspect of same female; c, dorsal 
aspect of the variety texanus, from Texas; d, ventral aspect of a light male from El Centro, California; e, dorsal 
aspect of the same male; f, lateral aspect of same male; g, dorsal aspect of a darkly pigmented male from 
Pasadena, California. 



160 times as much as the male! 

Of the three species, L. mactans averages smallest for both sexes. Thirty-seven males 
ranged from 2.9 to 5. 1 mm in length, with most between 3.2 and 4 mm; 52 females ranged 
from 5 to 13.5 mm, with most between 8 and 10 mm. Latrodectus variolas has the largest 
males, mostly between 5.5 to 6.5 mm, with a range for 34 specimens of 4.5 to 8.3 mm. 
Females of L. variolus are mostly 9 to 1 1 mm in length with a range for 32 specimens of 7.4 
to 13 mm. Latrodectus hesperus has the largest females, 59 specimens ranging from 8 to 
15.5 mm, with most from 10.5 to 13 mm. Sixty-three males ranged from 3 to 6.5 mm, with 
most between 3.8 and 4.5 mm. 

While it might appear that within a species the larger individuals would be those that 
have gone through more molts, and vice versa, this has not been found to be the case. Some 
of the smallest females of both L. mactans and L. hesperus matured in the sixth, the 
seventh, and the eighth instars, and one cannot ascertain their instar from the size. These 
size discrepancies can be seen among siblings in the same family, and as early as the time of 
emergence from the egg sac. By the time they have reached the fifth instar some may be 
almost twice the length of their sisters. The same applies to males, which when mature 
show a wide range in all three species. Again, this is irrespective of the instar in which they 
matured, or of the locality in which found. Two mature males of L. hesperus were collected 
quite close together at the same time at Yuma, Arizona. One, #1510, measured 3.4 mm 
and the other, #1511, was 6.5 mm long. Similar great discrepancies in size were found 



46 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

among males of Nephila inaurata (Walckenaer) reared from the same egg sac by Derouet 
and Dresco(1956). 

Although there is much variation, for females the first leg is proportionately longest in 
L. variolus. shortest in L. mactans, and intermediate in L. Hesperus. In males there is very 
little ditTerence between L. Hesperus and L. variolus. both of which have the first leg 
averaging slightly longer than in L. mactans. 

Besides dilTerences in the length of the legs, there are distinct differences in thickness. 
Again, it has not been possible to correlate this with species, though in general it seems that 
the first leg is slimmer in L. mactans females than in the two other species. However, in two 
females of L. Hesperus collected at Ramona, California, not more than 50 feet apart, one 
had a tibial index for leg I of 9.3, and the other, of 11.5. Exactly the same sort of finding 
has been noted for two females of L. mactans collected together in New York. This kind of 
variation in specimens from the same locality was also observed by Smithers (1944) in L. 
indistinctus. 

With some spiders there is a direct correlation between width of the carapace and 
stage of growth (i.e., instar). As indicated above there is a tremendous variation in size in 
Latrodectus even at the time of emergence from the egg sac. Newly emerged spiderlings of 
L. mactans usually range in length from 1.2 to 1.3 mm, with some up to 1.5 mm; those of 
L. Hesperus from 1.5 to 1.8 mm; and those of L. variolus from 1.7 to 2.0 mm, but 
sometimes down to 1.4, with the extremes even from the same egg sac. Furthermore, as 
reported by Shulov (1940) for L. tredecimguttatus, many spiderlings molted from the first 
to the second instar without having been fed, often within a day or two after emergence; no 
growth can be measured. After measuring many spiderlings, and in several families, I had 
to conclude, as had Miyashita (1968) for Lvcosa, that the width of the carapace could not 
be used for ascertaining the instar. 

EPIGYNUM 

The epigynum appears externally as a highly arched, heavily sclerotized structure 
which bulges ventrally, and has a transversely elliptical opening (Fig. 2c). There is much 
variation in the exact shape and relative length of the opening. In some specimens the 
anterior lip is developed into a carina, with or without a small median pointed process 
pointing toward the rear (Figs. 3, 7 and 9). Although not easily seen in the intact specimen, 
there is, on the dorsal wall of the atrium an opening on each side, leading into connecting 
ducts, the so-called bursae copulatrices. Examination of the cleared epigynum from the 
dorsal side shows that each bursa copulatrix is rather lightly sclerotized and twines around 
the heavily sclerotized, darkly pigmented spermatheca of its side. The spermathecae are 
dumb-bell shaped and lie with their axes making an angle of about 45 degrees to each other 
and their posterior rounded portions separated by a distance about half the diameter of one 
of them. 

The shape of the atrial opening, and the details of structure vary a little, but the general 
appearance is the same in all three species. Levi (1966) indicated that there was much 
variation in his material from Israel, and from the studies of Lucas and Bucherl (1965) one 
would expect some variation even in sisters. 

In L. mactans the connecting ducts have four outside coils (Fig. 2g), while in L. 
variolus (Fig. 14f) and L. Hesperus (Fig. 1 1 there are only three. This makes the epigynum 
of L. mactans appear wider than that of the other two species. Commonly the sperma- 
thecae and/or the connecting ducts will contain one or more embolic fragments left behind 
by the male after mating (Figs. 2g, 1 Ig, 1 Ih). 

According to Bhatnagar and Rempel (1962), who studied the structure of the 



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Figure 9. Ventral aspect of abdomens of L. Hesperus females to show variations in the shape of the epigynal 
orifice, and of the hourglass mark, a, from Texas; b, from British Columbia; c, from Washington; d, from 
California; e, from California; f, from California; g, from California; h, from British Columbia. 

epigynum of L. hesperus, the openings of the ducts into the spermathecae lie "on the 
middle portion of the spermathecae on the latter's outer lateral margin." 

In specimens one molt short of maturity the area where the epigynum will later show 
appears much arched. Thus it is possible to recognize one in the penultimate instar. In the 
antepenultimate instar the area is usually somewhat lighter than those surrounding areas, 
but definite recognition of females in this stage is not easy. 

PALPAL ORGAN 

Although Levi (1959) greatly reduced the number of species of Latrodectus, partly on 
the basis of similarity of palpal structure, he later (1966) admitted that the morphology of 
the palpal organ may be the same in two or more species. He accepted for North America 
only three species: L. mactans, in which the embolus shows three coils, L. geometricus. in 
which it shows four, and L. curacaviensis, in which it shows two. In 1964, with McCrone, 
he acknowledged that the true L. curacaviensis did not occur in North America, and that 
there were two additional species in which the embolus had two coils. These are L. bishopi. 
of south Florida, and L. variolas, which is widely distributed over the United States. 
Abalos and Baez (1967) and Pinter (1968) appear to have demonstrated that there are at 
least three additional species in the ""mactans group" and one additional in the ""curaca- 
viensis group." I consider L. hesperus a good species in the latter group, though some 
specimens show traits that would lead to its placement in the former group. This could 
account for Levi's distribution lists showing both L. mactans and L. variolus in the western 
States, where in my opinion neither one occurs. 

In all three species there is a long spirally coiled embolus (Figs. 1 la, b, c, 12a, b, 14a, 
b). The origin of the embolus from the radix is broad, and shows a thick curved tooth. 
There follows the heavily pigmented trunk of the embolus on the outside of the coil, 
paralleled by the membranous pars pendula on the inside of the coil. Near the distal end of 
the embolus is a blunt tooth marking the proximal articulation of the apical sclerite. After 
copulation the embolus breaks at this point, and the apical sclerite can be found lying 



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Figure 10. Lalrodeclus hesperus. a, female from California showing anterior chevron marks on abdomen, from 
the side; b, same female, showing chevron marks from above and front. 

within the parts of the female genitaUa (Figs. 2g, 1 Ig, h). This phenomenon, which in 
recent years has been shown to occur in other spiders too, was according to Gerhardt 
(1928) first described for Latrodectus in 1902 by Dahl. It was later noted by Smithers 
(1944), Abalos and Baez (1963, 1967), Gerschman and Schiapelli (1965), Wiehle (1967) 
and Bhatnager and Rempel (1962). The latter's work included detailed studies on the 
structure of the palpal organ and female genitalia. Their specimens had come from 
Kamloops, British Columbia, and from my own observations on abundant material from 
that very same locality it is quite certain that they were working not with L. ciiracaviensis 



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Figure 1 1 . Latrodectus hesperus. a, apical aspect of the palpal organ of the type male from Utah; b, the same, for 
a male from Arizona; c, same palp, ectal aspect; d, distal end of pedipalp of a male in the preantepenultimate 
instar; e, the same from a male in the antepenultimate; f, dorsal aspect of a cleared epigynum of a virgin female 
from Oregon; g, the same, from a California female that had mated, showing an embolic sclerite left behind in 
each of the spermathecae; h, the same, from another California female showing three embolic sclerites. indicating 
that it had mated with at least two males. 



as stated, nor with L. variolas as implied in McCrone and Levi (1964), but with L. 
hesperus. 

In the resting position, the distal end of the embolus usually lies against the conductor, 
but extends somewhat beyond it. Adjacent to the conductor is the heavier terminal 
apophysis, and just proximad of this is the sickle-shaped median apophysis. The distal 
border of the latter is provided with a socket into which fits a heavily sclerotized tooth 
borne near the distal end of the cymbium (Fig. 1 3a). Smithers described this tooth as two- 
lobed in Z.. indistinctus and L. geometricus, and indicated that these two species differed 
with respect to the size and shape of the two lobes. Levi (1959) referred to this cymbial 
tooth as a "paracymbial hook" and illustrated it for L. mactans, as well as for other 
species. It would seem that his usage of the term is ill-chosen, for the term paracymbium is 
already in use for a structure arising from the basal portion of the cymbium. In my studies 
on our three species I have found this tooth to be single-lobed, as illustrated by Bhatnagar 
and Rempel (1962). That Levi illustrates the tooth as two-lobed indicates a mis- 



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Figure 12. Latrodectus maclans. a, apical aspect of palpal organ of a male from Florida: b. ectal aspect of same 
palp: c, distal end of pedipalp of a mature female: d, distal end of pedipalp of an antepenultimate male: e, distal 
end of a pedipalp of a penultimate male: f, dorsal aspect of a penultimate male from Florida; g, ventral aspect of 
same male. 

inlerprelation. The tooth is strongly sclerotized and pigmented, and from the point of its 
attachment at the edge of the cymbium the latter shows the same degree of sclerotization 
and pigmentation. This may give the impression of a two-lobed process (Fig. 13a). But if 
one views the structure from the apicomesal (Fig. 13b), the mesal (Fig. 13c) or the ectal 
aspect (Fig. 13d) its single nature can be seen. 

Levi found, that to some extent at least, the character of the embolus could be used to 
separate species. In L. variolas it is wider than, and about three-fourths as long as, in L. 
mactans. and it makes two coils in L. variolus. but three in L. mactans. Moreover, I noted 
that the coils are tighter and less open in L. variolus than in L. mactans. 

In the type male of L. Hesperus the embolus (Fig. 1 la) shows two coils (as in the 
"curacaviensis group") though it appears longer than in L. variolus, as the coils are more 
open. However, the coils are tighter and less open than in L. mactans. But there is much 
variation among the many specimens of L. Hesperus that have been studied. In fact I have 
seen many specimens that could not be identified on the basis of coil morphology. For 
example, figure 13h represents the palpal organ of a L. Hesperus specimen from Los 
Angeles, California, and figure 13k the same of a L. mactans specimen from Rutledge, 
Georgia. Note the similarity between figure 13g of a Gainesville, Florida specimen of/,. 
mactans. and figure 13e of an El Centre, California specimen of L. Hesperus. Adding to the 
confusion is the fact that the basal portion of the embolus sometimes extends from its 
origin towards the distal end of the palp, sometimes towards the basal, or the mesal, or the 



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Figure 13. a, cymbium of pedipalp of a New York specimen of L. maclans; b. cymbial hook as seen from the 
apicomesal aspect; c, the same, mesal aspect; d, the same, ectal aspect; e, embolus of L. hesperus male it 1002-A- 
51 from El Centro, California; f, the same, of a litter-mate, * 1002-A-48; g, the same, ofZ,. mactans msAt #1005- 
B-39 from Florida; h, the same, of L. hesperus male from Los Angeles. California: i, the same, of L. mactans 
male #1005-C-29 from Florida;], the same, of L. maclans male #1005-8-49 from Florida; k, the same, of Z.. 
mactans from Georgia. 

ectal sides; and Levi's illustrations likewise show these variations. The problem becomes 
one of deciding where to make the coil count, since, of course, it is not a matter of 
concentric circles, but of a spiral. Even two brothers may look quite different, and have 
been mistakenly considered as belonging to different species, e.g., L. hesperus # 1002-A-48 
(Fig. 13f) and #1002-A-51 (Fig. 13e). Obviously, therefore, one must expect some 
specimens of L. hesperus to show an apparent three coiled condition. The same is 
sometimes noted with brothers of /.. mactans, e.g., #1005-6-39 (Fig. 13g)and #1005-6-49 
(Fig. 13j). Note the similarity between the latter and figure 13f of the L. hesperus specimen. 
Also note the similarity between the former and the L. hesperus figure 13e. Many other 



52 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

variations occur, and the figure 13i shows another L. mactans, brother of the previous two. 

Levi's (1959) specimen from Colorado (undoubtedly L. Hesperus) illustrated in his 
figure 58 and labelled L. mactans by him appears almost identical with my L. hesperus 
from Los Angeles, figure i3h. Similarly, in his figures 40 through 47, representing L. 
geuinetricus. some appear to show the four coils characteristic of that species and others 
show only three. Likewise, his figure 61 of a Peruvian L. mactans is almost identical with 
his figure 47 of a L. geometricus from South Africa; both show three coils over part of the 
circumference, and four over part. 

It would seem that the number of coils of the embolus cannot be used alone as a 
character for separating the species. Yet in effect this is presumably what Levi has done, 
and because he has found in Utah (and other western States and Provinces) both three- 
coiled and two-coiled specimens he naturally supposed that he had both " L. mactans and 
L. curacaviensis [ actually L. varioliis ] both of which are found in Utah," and that 
Chamberlin and Ivie failed to distinguish them. As has been previously indicated, I believe 
that our western black widow is L. hesperus, and further that the variety texanus is a 
variety of L. hesperus, and not of L. mactans in the strict sense. 

In nearly all araneomorph spiders the male can be recognized in the penultimate 
instar, because the palpal tarsus appears bulbous then (fig. 12e). Because the palpal organ 
in Latrodectus is relatively large, its development begins even before the penultimate 
instar. Hence the palpal tarsus is slightly swollen in the antepenultimate instar (Fig. 12d) so 
that it is possible also at this stage to recognize a male. The swelling may be noticed even in 
the preantepenultimate instar (Fig. 12c) as suggested by Bhatnagar and Rempel (1962), but 
I have not found this a constant character. On the other hand I have noted a number of 
instances in which there are three (not just two) instars preceding the penultimate one, in 
which a slight enlargement of the palpal tarsus gives an indication that the specimen is a 
male. I have also noticed that the degree of swelling is not the same for all individuals in the 
preantepenultimate or antepenultimate instars. There are indications that some expansion 
occurs during an instar itself 

INTERNAL MALE GENITALIA 

Chromosomes were studied in the cell divisions taking place in the testes. The detailed 
description of meiosis and of the individual chromosomes is being reserved for a separate 
publication elsewhere by Barbara Kaston. Suffice it to say that in all three species she has 
found that the sex chromosome situation is of the X] XtO type, so that in the female the 
diploid condition shows two chromosomes more than in the male. 

The dissection of the testes was carried out by submerging the freshly severed 
abdomen in frog Ringer's solution and pinning it venter down in a wax-bottomed dish. A 
cut was made along the middorsal line and the dorsal exoskeleton removed. Usually the 
heart remained adherent to the exoskeleton, and the testes became visible as two tubes only 
slightly kinked, and arched (Fig. 19c) to more or less conform to the curve of the dorsum. 
The testes are loosely attached to each other by short bands of connective tissue and at the 
posterior end are attached in the region of the spinnerets by a longer ligament. At the 
anterior end of each testis is a ductus deferens, which extends forward, then downward and 
backward, joining its mate just before the gonopore at the middle of the epigastric furrow. 

It should be noted that although Millot (1949) described the testes of spiders as lying in 
the ventral half of the abdomen, and below the chylenteron, and his figure 454 shows this 
for Scytodes thoracica, in Latrodectus the testes for most of their length lie fairly close to 
the heart in amongst the chylenteric ceca. While not as short and straight as given by 
Bertkau (1875) for Tegenaria domestica, they are not as long nor as convoluted as in the 



1970 



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53 











Figure 14. a, apical aspect of palpal organ of male L. variolus from Connecticut; b, same palp, ectal aspect; c, 
outline of abdomen of male L. Hesperus from the left side, showing position of testes in situ; d, testes straightened 
out as they appear from above; e, sperm cells of L. Hesperus; f, dorsal aspect of cleared epigynum of a mated 
female of L. variolus from Michigan, that had mated, showing an embolic sclerite left behind in each of the 
spermathecae; g, egg sac of L. Hesperus, natural size; h, egg sac of L. mactans, natural size. 



theraphosid illustrated by Melchers (1964). If removed from the abdomen and straightened 
out somewhat they appear with gently undulating walls (Fig. 14d), each testis 
approximately 2.4 to 2.7 mm long and about 0.25 mm wide. The ductus deferens extends 
for about another 0.4 to 0.6 mm from its anterior end. In the fresh condition the testes 
appear grayish opalescent in contrast to the chalky white of other adjacent structures. 

Upon crushing portions of the testis in frog Ringer's solution and examining on a slide 
one can make out the sperm cells. These appear as in figure 14e, with the head piece rather 
elongate, and at least slightly curved. Some spermatozoa show the head pieces curved even 
more, with much variation all the way to those showing the head in a tight spiral. For L. 
hesperus the head piece measures about 19 to 21 microns in length by 3 or 4 in width. The 
flagellum appears attached asymmetrically and is about 30 microns in length. In L. 
mactans the head piece is 15 to 18 microns long and the flagellum 30 to 35. Very little is 
known about spider spermatozoa, but recently Bacetti et al. (1970) working with Pholcus 
phalangioides. Agelena labyrinthica, and Pardosa vittata likewise reported a flagellum 
length of about 30 microns. The head portion was not described or illustrated, but these 
workers commented on the fact that while in the testes the head portion is spirally curved. 



54 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 



COURTSHIP AND MATING 

In nature, mating most often occurs in the late spring and early summer, but in mild 
climates, such as along the Pacific coast and in our southern states mating pairs may also 
be seen in late summer and early fall as well. 

The courtship and mating behavior for L. hesperus was reported by Herms et al. 
(1935) and D' Amour et al. (1936). and for L. bishopi by McCrone and Levi (1964). It is 
essentially similar to that described by Gerhardt (1928) for L. tredecimguttatus. by Shulov 
(1940) for that species and L. pallidus, and for L. indistinctus by Smithers (1944). 

Presumably, before the male begins his search for the female, and courtship is to 
begin, the male will charge his palpal organs with semen. I have not observed this process 
of sperm induction. Herms et al. (1935) reported that they had seen it, but gave no details. 

The length of the courtship preliminaries varies, but generally is shorter with young 
females than with older ones. For these observations the female was allowed to establish 
herself for at least a week in a large glass cage. The male was introduced at the upper 
corner farthest from the female. 

Almost immediately upon being put into the female's cage the male shows signs that 
he is aware of the female's proximity. The abdomen is vibrated rapidly, and with jerky 
movements of the legs the male wanders about, every once in a while twanging the threads 
as he progresses. Eventually he heads in the direction of the female. Within 10 or 15 
minutes he begins a new maneuver, which consists of cutting portions of the female's web. 
He continues this cutting as he approaches her, so that the silk is gathered up in 
concentrated bands and sheets, instead of appearing spread out as before. Sometimes the 
female charges at him. whereupon he hastily retreats. After a short rest with his abdomen 
not twitching, he once more approaches her. This charging and retreating may be repeated 
several times, but if it continues and the female becomes violent in her rushing, the male 
may remain at a distance and eventually discontinue his courtship. 

If the female is not too aggressive he may find himself within touching distance of her 
within 30 minutes (Fig. 15). With his front legs he strokes and taps her legs, and then her 
body. This contact heightens his excitement so that his abdomen twitches more rapidly. If 
the female does not kick him away she too may begin to engage in leg stroking activity. 
The male then walks over and around the female jerkily, at the same time surrounding her 
with silken threads. This "bridal veil," which I have seen used by crab spiders and others, 
was observed for Latrodectus by Gerhardt, and by Smithers, as well as by Herms et al., but 
was apparently not observed by McCrone and Levi. As Smithers indicated, the threads are 
too fine to hinder her when she later decides to break loose, but serve to remind her that 
"her partner is in attendance." 

Sooner or later in his wanderings over her body, with his pedipalps constantly tapping 
her, he locates the epigynal area. Some time may be spent "boxing" this area, apparently 
in an attempt to hook into the opening. Finally, after having been in the female's web about 
100 to 140 minutes, he assumes the copulatory position, position III of Gerhardt, in which 
both sexes face the same way, venter to venter (Fig. 1 b). 

Sometimes the right palp is used first, and sometimes the left. When the palp is 
hooked into position, the embolus is inserted and the hematodocha distended, then 
deflated, indicating that semen is being transferred. Insertions may last from one to 32 
minutes, but most often from 4 to 8. Sometimes the female struggles out of her bonds after 
only a few minutes, too short a time for the male to have inserted more than one palp. She 
may now turn upon him aggressively, so that he is forced to retreat. 

Often the male will try again by going through the same ritual of cutting web lines. 



1970 



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Figure 15. Courtship pairs, a, L. hesperus. b, L. mactans. 



twanging threads, and vibrating the abdomen. 

If the female remains still after the first palp is withdrawn, the male will insert the 
other palp. This occurred in about one third of the matings observed. It is well known that 
when the female frees herself from the "bridal veil" the male may be in danger. If she is 
hungry she may kill and eat him. With well fed females this is not likely to happen, and I 
have on several occasions left the male in the cage with her. In the course of time, two 
weeks or more, the male dies untouched by the female. 

Upon withdrawal of the embolus the distal sclerite is left behind in the genitalia of the 
female. Depending upon whether one or both palps have been used, there will be one or two 



56 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

sclerites (Figs. 2g, 1 Ig). But sometimes one epigynum will show three sclerites (Fig. 1 Ih) 
indicating that the female had mated with at least two males. 

Of 51 attempts with L. hesperus, where courtship was carried out, there were 12 
successful cases of insemination. Of 13 attempts with L. mactans, 5 were successful, and of 
8 attempts with L. variolus 5 ended successfully. The behavior appeared the same in all 
three species. When insemination did not occur, it was usually because the female repulsed 
her partner before the act could be completed. 

I tried to induce interspecific crosses between L. variolus and L. mactans (4 attempts) 
and between L. variolus and L. hesperus (18 attempts) none of which terminated in an 
insemination. Three of 27 attempts between L. mactans and L. hesperus were successful, 
but there was no development of eggs laid by these females. 

CONSTRUCTION OF THE EGG SACS 

Whereas the egg sacs of the three species vary somewhat in size, shape, and color, they 
all appear to be of tough papery texture, usually only slightly translucent. In this respect 
they are similar to the sac of L. bishopi, but quite dilTerent from that of L. geometricus, 
which is non-papery and quite translucent. Sacs made by virgin females may be abnormal 
(Kaston, 1968). The sacs of L. hesperus and L. variolus are pear-shaped (Fig. 14g), and 
often somewhat spread at the top, about 13 or 14 mm in height and about 10 or 12 mm in 
diameter. Those of L. hesperus are most often creamy yellow to light tan, those of L. 
variolus light tan with most often a tinge of gray. The sacs of L. mactans almost always 
show the gray tinge and often are quite decidedly gray, even when freshly made. Also, they 
are more nearly spherical, about 1 1 or 12 mm in diameter, and with a conspicuous nipple 
at the top (Fig. 14h). 

At times the sacs do not show the typical color. McCrone and Levi (1964) indicated 
that sacs of L. bishopi dilTer from those of L. mactans in having a soft texture and being 
white in color. But the sacs of L. bishopi I have seen are just as papery as those of L. 
mactans and are light tan. The sacs of Z,. geometricus are studded with conspicuous pom- 
pons, whereas the other species make sacs without these surface features. But Abalos 
(1962) and Abalos and Baez (1967) indicate that apparently there is a species in Argentina 
(their Lairodectus No. 2) which does have pom-pons on the surface, albeit they are smaller 
and less conspicuous than those of L. geometricus. Likewise, occasional sacs made by L. 
variolus appear to have very small, irregularly distributed, whitish pom-pons showing up 
against the gray surface. This has been observed with specimens from Arkansas, Michigan 
and Missouri. 

Nearly all of the hundreds of egg sacs made in the laboratory were made during the 
night. However, of those made in daylight four of L. hesperus were begun after noon, and 
27 before noon; five of Z,. mactans were made in the morning and one in the afternoon; and 
for L. variolus four were made before noon. The behavior is about the same in all three 
species, and the construction may be conveniently divided into four steps. 

The egg sac is begun with the laying down in step I of the canopy, a small circular 
sheet, which is gradually enlarged so that its diameter is about that of the completed sac. 
As the spider finishes the periphery of the disc she also slowly pulls it into the shape of a 
shallow cone with a slight peak. The duration of step I averages about 23 minutes. 

Proceeding to step II the spider stands under the canopy and extrudes the mass of eggs. 
This is done with rapid upward jerks of the abdomen at the rate of about 1 00 to 1 20 times 
per minute. The jerking expels the eggs and coUeterial fluid which cements them together, 
and also pushes the eggs higher toward the canopy. This step averages about 1 1 minutes. 

The female next begins spinning a transparent layer of gauzy silk around and under 



1970 



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57 




Figure 16. Egg sacs of L. Hesperus from California, a, sac opened to show eggs shortly after ovipositon; b, 
embryos ready to hatch; c, adult fly parasites, Pseudogaurax signala, on egg sac; d, maggots and puparia of 
Psuedogaurax in amongst spiderlings. 



the egg mass, and about 5 or 6 mm from it. She works from the canopy downward and 
finishes at the bottom where the egg mass usually soon comes to lie (Fig. 21b). The egg 
mass itself comes to occupy one-half to two-thirds the volume of the sac. This step III 
averages about 25 minutes. 

The final action, in step IV, consists of covering the sac with tough, more or less 
opaque papery silk, and averages about 100 minutes. During the first 10 to 15 minutes of 
this period the spider walks around over the sac, drawing out silk with her hind legs and 
tapping with her spinnerets at the rate of 60 times per minute. Later, the hind legs are no 



58 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

longer used, but rather, the silk is applied directly each time the spinnerets touch the sac, 
now at the rate of about 120 times per minute. Since the abdomen is brought up to the sac a 
distance of several millimeters it is this length of thread which is applied each time a tap is 
made. The rate of tapping may rise to 150 and even 200 times per minute (in one case to 
240) as the work continues. At intervals she turns the sac about. During the final 30 
minutes or so she stops for several brief rests. 

The sac is ordinarily suspended in the snare (Fig. 21a), in or near the retreat if one is 
built. Sometimes eggs are laid without any sac whatever. They are merely dropped to the 
bottom of the cage. Rarely this behavior is displayed by impregnated females; more 
usually by virgins. 

NUMBER OF EGG SACS AND FECUNDITY 

The interval between copulation and the production of the first egg sac varies 
considerably. While Abalos and Baez (1967) found this interval to be 7 days for L. 
geometricus. and Miller (1947) found it to be 61 days for L. Hesperus, the period noted by 
D'Amour et al. for this latter species was over a year. My own records show for L. 
Hesperus that the shortest time was 7 and the longest was 305 days; for L. mactans 16 and 
22 days; and for L. variohts 14 and 27 days respectively. 

Black widow females are capable of making many egg sacs. The highest number 
reported is 29 for L. geometricus by Bouillon (1957a). According to Burt (1935), 
Illingworth reported 15 for L. mactans; nine is the maximum reported for L. indistinctus 
by Smithers (1944), for L. Hesperus by Chamberlin and Ivie (1935), and for L. curaca- 
viensis by Bucherl (1969); and eight for L. tredecimguttatus by Juberthie (1954). My own 
observations indicate up to 6 for L. variolus, 10 for L. mactans, and 21 for L. Hesperus. 
Since 1 had relatively few specimens of L. variohis, and had them for a relatively short 
time, I cannot be sure of the significance of the figure for that species. But there were a 
surticient number of specimens of L. mactans, and they were maintained for a sufficiently 
long time so that it may be safely said that there are fewer egg sacs made by this species 
than by L. Hesperus. However, they lay more eggs per sac on the average, the mean for 185 
sacs being 255 eggs, while for L. Hesperus the mean of 464 sacs was 196 eggs. 

A maximum of 5761 eggs laid by a single female of L. geometricus was reported by 
Bouillon (1957a). For L. mactans I found that the greatest productivity was 2132 eggs in 
the nine sacs made by #1221. The largest number of eggs per sac was 919, followed by 530, 
435, and only a few sacs with over 300. The most common range was 2 1 5 to 237. There was 
one sac with a single egg, and five others with fewer than 100. For L. Hesperus the largest 
number of eggs per sac was 598, and the same female produced a sac with 527. The next 
highest was 427, and very few sacs had over 300. Commonly the range was 160 to 225. 
There was one sac with a single egg, and five others with fewer than 10 eggs each. The 
greatest productivity was 3024 eggs for the 12 sacs made by # 1002. The largest number of 
eggs laid in one sac by L. variohis was 3 1 5, and the mean for 34 sacs was 1 64 eggs. 

Baerg (1945, 1959) reported L. mactans females producing four to nine sacs with the 
largest number of eggs in the early ones, and fewer in the later ones, the last one or two 
often being empty. I did not find this to be the case. The number varied from one sac to the 
next, sometimes smaller, and other times larger. 

Bouillon and Lekie (1961) noted that in L. geometricus eggs were laid at intervals of 
four days for the first few sacs, but the intervals became progressively longer. On the other 
hand 1 found that the intervals between successive sacs varied widely. The shortest period 
lor /,. Hesperus was six days between the eighth and ninth sacs made by #2130; the longest 
was 332 days between the second and third sacs made by #1069. For L. mactans the 



1970 



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59 



shortest interval was six days between the second and third sacs of # 1 147; the longest was 
190 days between the first and second sacs of # 1 192. For L. variolas the shortest was 13 
days between the second and third sacs of # 1376, and the longest was 1 13 days between the 
third and fourth sacs of the same spider. No trend for either increasing or decreasing the 
interval can be seen from the data, and as can be seen from table 1 the coefficient of 
variability indicates wide variation in the spacing of sacs. 



Table 1 . Interval between ovipositions. 









Number 

of 
Females 


Number 

of 

Sacs 




Inter 


val; in 


days 




Coeff. of 
Variation 




Range 




Mean 




S.D. 


I L. 


variolus 


Virgin 


4 


7 


17-86 




28.9 




± 25.6 


88.6 


Non-Virgin 


11 


20 


13-114 




30.0 




± 29.5 


98.3 


L. 


mactans 


Virgin 


5 


10 


13-190 




40.0 




±171.8 


429.5 


Non-Virgin 


43 


128 


6-190 




33.5 




± 29.0 


86.6 


L. 


hesperus 


Virgin 


48 


156 


1-332 




49.5 




±175.8 


355.2 


Non-Virgin 


109 


672 


7-305 




34.8 




± 29.7 


85.3 



Naturally one could hardly expect that all the eggs laid would actually develop. Very 
few sacs showed a development of 100% of the eggs. However, it would be reasonable to 
expect that those sacs produced early in a series would show a higher percentage of fertility 
than those made later. Sometimes the first five to seven sacs from a single female showed a 
fertility percentage of 98 or 99. Though one would expect that later sacs might show an 
increasingly lower fertility this did not follow in any regular manner. For example, for L. 
hesperus #2130 the first five sacs showed over 90% development from each. From the 
sixth sac only 30% of the eggs developed, yet the next six sacs averaged a development of 
over 90 % again ! The 1 3th (and final) sac had 78 % of the eggs developed. There were many 
other instances where a sac would show no development whatsoever, then later sacs show a 
fairly high percent of fertility. I could find no pattern of increasing or decreasing fertility. 

Usually, when a large number of eggs is laid and only a few develop, the spiderlings do 
not emerge from the sac. There are exceptions, an outstanding one being the case of egg sac 
#1050-B, of L. hesperus. where of the 208 eggs laid only one developed, but the spiderling 
emerged. 

A Connecticut specimen, presumably of L. variolus, mature when collected on 10 
April 1949, produced an egg sac on 17 June 1950 from which spiderlings emerged. Since 
the female had not been mated in the laboratory at least 434 days had elapsed from the 
time of mating to the time of fertilization. This longevity of sperm cells, which is 
considerably greater than that of the male spider that made them, is exceeded in two 
instances by L. hesperus. One #1053, collected already mature on 6 December 1965 
produced her fourteenth egg sac on 4 February 1967, from which spiderlings emerged. 
Thus the sperm cells remained viable for at least 455 days. Also, #1202, collected already 
mature on 12 December 1966 produced her fourteenth sac on 24 April 1968. Of the 170 
eggs laid, 36 developed into spiderlings, indicating that sperms had lived at least 499 days 
after insemination. Actually the correct figure is nearer 600 days, for this female at the 
time of collection already had five egg sacs in her web. 



60 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

DEVELOPMENT WITHIN THE EGG SAC 

In all three species the eggs may be occasionally lavender-pink or mauve. However, 
most often they are creamy white to yellow, and sometimes orange. The same sac may 
contain eggs of more than one color but the further development bears no relation to the 
color. The eggs are spherical, or almost so; those of L. mactans average about 0.95 mm in 
diameter; of L. hesperus about 1 . 1 mm, and of L. variolus about 1 .2 mm in diameter. 

To obtain data on pre-emergence development many sacs were opened (Fig. 16a) 
within a day of oviposition. These sacs were placed in vials of which the plugs were kept 
moistened to protect the eggs from total drying. Within a day of oviposition the eggs dried 
sufficiently to roll around freely. If dropped on a hard surface they would bounce and roll, 
seemingly without injury. 

Although Baerg (1945) reported hatching in L. mactans after only 8 days, in my 
experience the hatching time for all three species was nearer two weeks. The average time 
in days was 13.4 ± 2.0 for L. variolus, 14.2 ± 1.4 for L. mactans. and 14.6 ± 2.0 for L. 
hesperus. About a day or so before hatching the membranous surface of the egg becomes 
wrinkled, and one can see the outlines of the cephalothorax and appendages as bulges (Fig. 
16b). The newly hatched spiderlings are entirely unpigmented, without eyes or hairs, and 
they move feebly. Within a day after hatching the first sign of pigmentation appears as a 
ring at the periphery of each anterior median eye. The six indirect eyes begin to develop 
their pigment a day or so later. Also, about this time, fine black hairs begin to show up on 
the dorsum and legs. In addition, the legs show a slight yellowing. That the spiderlings 
undergo their first molt inside the sac was first reported by Rau (1924) and this occurs 
about three or four days after hatching. 

During the next five to seven days, pigment is gradually deposited in the characteristic 
pattern. Also, the spinnerets develop to the point where they can function, so that by the 
end of this period the spiderling begins to spin silk as it crawls about among its fellows in 
the sac. Twenty to 23 days after oviposition the youngsters appear ready to emerge from 
the sac. However, the actual emergence does not usually take place for another few days, 
during which time there is somewhat more pigment deposited in the pattern. The average 
time, in days, from oviposition to emergence was 26.2 ±2.2 for L. variolus, 29.1 ±3.0 for 
L. mactans, and 30.3 ± 2.8 for L. hesperus. 

EMERGENCE 

An emergence hole is visible about a day or so before the spiderlings actually emerge. 
The hole is made by cutting with the chelicerae, and possibly also by digesting away the silk 
by regurgitated proteolytic enzymes. At least I have seen what appears to be a moistened 
area on the silk as the chelicerae are worked around enlarging the hole. Ordinarily a single 
hole is cut allowing escape of the spiderlings. This hole, about 1 mm in diameter, may be 
made by one spiderling, or by two working together. A few sacs have been found with two 
exit holes, and rarely with three. 

If, after the escape of one or more spiderlings, the exit hole is now covered over or 
plugged with glue, a new hole will be made by the remaining spiderlings Even a third hole 
will be made if the second is plugged. On the other hand some sacs remained unopened, 
and the spiderlings were later found dead in the sac, e.g., #1374-B of L. variolus from 
Michigan, #1380-8 of L. mactans from Missouri, and #14 15- A of L. hesperus from 
Texas. In a few sacs spiderlings did not emerge but nevertheless grew and molted, in one 
case to within one instar of maturity (Kaston, 1968). In another sac, of L. mactans from 
Illinois #1283-8, there was no emergence six months after the eggs were laid. In the sac 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 61 

were 8 spiderlings among a large mass of undeveloped eggs. Of the 8 spiderlings one was a 
large male, probably in the fourth instar to judge by its size and markings, which by its 
palpal development appeared to be in the antepenultimate instar. The other seven looked 
like third and fourth instar females. Usually when growth and molting occur without 
emergence, there are few spiderlings and a relatively large number of undeveloped eggs; 
and the spiderlings obviously have been feeding on the eggs. In fact, when a sac has only a 
small number of spiderlings emerging, and a large number of undeveloped eggs, the 
spiderlings are often larger and in the second post-emergence instar, making it appear that 
they have been feeding on eggs. This phenomenon has been recorded for L. tredecimgut- 
tatus by Juberthie (1957) and for L. geonietricus by Bouillon (1957a). It seems, however to 
be of even more general occurrence, having been observed by Galiano (1967) in Loxosceles 
laeta, and in Gnaphosidae and Clubionidae by Holm (1940). The latter also indicated that 
it had been observed by Wagner in Lycosidae, by Becker in Drassodes lapidosus, and by 
Lecaillon in Chiracanthium carnifex. Peck {in litt.) informed me that he had observed the 
same in C. inclusum. 

Often eggs may not develop to the hatching stage, and of course not all spiderlings 
emerge even when a hole is cut and the majority escape. Baerg (1954) considered that 
drought was a factor in failure to hatch, but in view of the fact that many black widow 
spiders live in arid regions, and judging from the studies of Shulov (1940) and Bouillon 
(1957b) it is hardly likely that drought is an important factor. Also, Baerg believed that 
emergence coincides with the end of the first instar, when in fact the molt to the next instar 
generally occurs some time after emergence. 

DESCRIPTION OF POST-EMBRYONIC STAGES OF DEVELOPMENT 

Among the exotic species the young of L. tredecimguttatus were first described by 
Duges (1836), and more recently by Marikovskii (1947) and by Shulov and Weissman 
(1959); of A. indistinctus and L. geonietricus by Smithers (1944); of A. revivensis by Shulov 
and Weissman ( 1 959); and of L. pallidus by the latter and by Beregovoi ( 1 962). 

Some authors have indicated periods in the life cycle by specifying the number of 
molts (to maturity, etc.). Others have referred to stages, with the first being the one after 
hatching from the egg. This takes place inside the egg sac, as does also one molt before 
emergence. Often an additional molt, or two, occur inside the sac as mentioned above. 
Ordinarily the spiderling will leave the sac during its second true instar. However, for 
convenience I have designated this post-emergence nymphal instar as the first instar, as 
was done by Miyashita (1968). For the sake of uniformity in making comparisons 
therefore, the results stated by other authors have been converted to this system. 

There is a wide variation in appearance among both adults and juveniles. As long as it 
was supposed that all North American forms belonged to the one species, L. mactans, this 
variation seemed even wider, but even with the acceptance of L. variolus, and now of L. 
hesperus. there is still much variation in each. 

The drawings for each instar give some idea of the appearance of a common form, but 
it must not be expected that all specimens will look exactly like these. Even siblings from 
the same egg sac may vary widely, and even by the time they emerge. In addition, I have 
raised many females, which upon maturity assumed a pattern quite different from that of 
their mother. 

Another type of variation is that occasioned by the spiderlings changing their 
appearance during a given instar, as originally observed by Moles (1916). In general this 
means that some third instar spiderlings may resemble some second, and others may 
resemble some fourth instar individuals. Presumably this change is somehow related to 



62 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

nourishment during this time. At any rate, those spiderlings which were not fed during the 
first instar, and yet molted, changed very Httle. 

Still another type of variation is geographic. This had been recently demonstrated for 
Peruvian specimens of L. mactans, by McCrone and Levi (1966), and it had been noted by 
others as well. Smithers (1944) encountered it in his studies on L. indistinctus in South 
Africa, and I have seen many examples of it in our three species from all over the United 
States. 

To some extent the appearance of the adult is correlated with the instar in which the 
individual matured. Those maturing in later instars may be darker than those maturing in 
earlier. However, this is not absolute, and I have found that many specimens maturing in 
the sixth, seventh, and eighth instars cannot be told apart. McCrone and Levi (1964) 
reported ''noting a striking correlation between total length of the spider and the 
coloration of different forms, the smaller being brightly colored, the largest ones dark." 
This correlation seems high, but it is not perfect. Also, smaller specimens can be lacking in 
red markings as much as larger specimens. 

Latrodectus mactans 

FIRST INSTAR (Figs. 17a, b). — The carapace is mostly yellowish suffused with gray, with 
black around the eyes, and with black marginal and median stripes. The sternum is yellow 
with a very thin marginal black stripe. The legs are yellowish orange, at most only very 
faintly annulate with dusky, but usually somewhat grayer toward the distal ends of the 
tarsi. 

The abdomen is orange-red, with a pair of anterior white bands, often joined across 
the front as a single "chevron" mark, a median white band, and two pairs of diagonal white 
bands extending laterally. The median band may be divided into two, three, or four spots, 
by encroachments, at intervals, of the orange-red ground color. In many specimens the 
white lateral bands are bordered along the posterior edges by a line of black pigment. 
There may also be thin black lines along the sides of the median light band. But many in 
the same brood of spiderlings show no black at all in this stage. 

There is a conspicuous black spot covering the spinnerets and anal tubercle. Many 
specimens already show an indication of an hourglass mark, but with others the reddish 
orange pigment seems evenly distributed over the venter and sides. 

SECOND INSTAR (Figs. 17c, d). — The general impression is that there has been a marked 
change from the first instar, with much black pigment deposited. On the carapace the dark 
marginal bands are broader, and even the light areas are suffused with gray. The sternum 
likewise is darker. On the legs the annuli are now distinct. Leg I has the femur with the 
basal half dark, and the distal half light, except for a small dark ring at the apex; the 
patella is suffused with gray; the tibia has a dark ring at each end, and one just about at its 
middle; the metatarsus and tarsus are without dark annuli. Leg II has the femur yellow, 
except for a small dark ring at the apex; the patella has a faint indication of a dark ring 
distally; the remaining segments are like those on leg I. Leg III has the femur with a dark 
ring at the apex, and a dark ring at each end of the tibia; otherwise it is like leg I. Leg IV 
has the femur with a dark area occupying the middle half of the prolateral surface, then a 
ring at the apex; the patella has a distal dark ring; and the remaining segments are like 
those on leg I. 

On the dorsum black bands alternate on each side with creamy white areas (Fig. 17c). 
There is almost always a light median spot, followed by a light median band, which 
however, may be broken into spots. In some specimens these white areas have a little 
orange pigment in their centers. The venter plainly shows the hourglass mark, which is 



1970 



KASTON: AMERICAN BLACK WIDOW SPIDERS 



63 














Figure 17. Postembryonic development stages of L. maclans. a, first instar, dorsal aspect; b, the same, ventral 
aspect; c, second instar, dorsal aspect; d, the same, ventral aspect; e, third instar, dorsal aspect; f, the same, 
ventral aspect; g, fourth instar, dorsal aspect; h, the same, ventral aspect; i, fifth instar, dorsal aspect;], the same, 
ventral aspect; k, sixth instar, dorsal aspect. 

much more constricted in the middle than with L. hesperus. 

THIRD INSTAR (Figs. 17e, 0- — The gray areas are now larger on the carapace as well as 
on the sternum, where the light area is reduced to a median narrow stripe. The legs are 
much darker, though annuli are still visible. The most noticeable change is on the 
abdomen, where the black areas are much larger, with the consequent decrease in size of 
the light areas. This is particularly noticeable in the mid-dorsal stripe, which is now broken 
up into more spots. The hourglass mark is more distinct, and is bordered with black. In 



64 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

some individuals it is quite red, in others it is almost white. 

There is a great deal of variation. Some individuals look much like those in the second 
instar, and others like those in the fourth. The degree of blackness varies widely. Some 
have the white areas quite restricted; some show only black and white, but no red on the 
dorsum; others show only black and red, with no white on the dorsum. 

FOURTH INSTAR (Figs. 17g, h). — The carapace is darker. The midline stripe on the 
sternum is narrower. The legs have changed little, but the dark areas are a bit more 
extensive. The abdominal dorsum shows the light areas still further reduced in size. Of 
those specimens with white, rather than red, spots, most show orange pigment in the 
centers of these white spots. As in the preceding instar there is considerable variation, 
many specimens looking like third and many like fifth instar individuals. Many males show 
by the enlargement of the palpal tarsus that they are in the penultimate instar. 

FIFTH INSTAR (Figs. 17i, j). — There is relatively little change from the previous stage, 
with a continuation of the overall darkening, as the black pigment spreads. The legs are 
still banded. On the dorsum the white diagonal bands are thinner and shorter, and often the 
third (or most posterior) pair is absent. 

SIXTH INSTAR (Fig. 17k). — The carapace is quite black. The legs are almost all black, 
with the former light areas being dark brown. However, some specimens may show the 
annuli slightly. On the dorsum the white diagonal bands are very much reduced; the first as 
a small chevron mark, and the second as a faint remnant. Sometimes the chevron is 
represented as a pair of red spots. The spots of the median row are now bright red. In many 
specimens the spots tend to disappear from anterior to posterior so that in some there 
remains only the most posterior spot just above the anal tubercle. Some of the females 
mature in this instar. 

SEVENTH, EIGHTH AND NINTH INSTARS. — Most females mature in these instars. There 
is usually only a remnant of the chevron mark at the front of the dorsum. The diagonal 
light bands have disappeared entirely, or are at most only very faint, so that the only spots 
remaining are the red ones of the median row, and even these may be reduced to just one 
above the anal tubercle. The hourglass mark usually consists of an anterior triangle and a 
narrower posterior rectangle with rounded corners. 

Latrodectus hesperus 

FIRST INSTAR (Figs. 1 8a, b). — The ground color of the carapace is dusky grayish yellow. 
However, the eye region is black, and there are three black longitudinal stripes. One of 
these extends from the median eyes to the rear; the other two are along the lateral margins. 
The sternum has similar marginal bands, but is otherwise dusky yellow. The legs have the 
same ground color as the carapace. Leg III is much less pigmented than the others, and is 
dark only at the distal end of the tarsus. The other legs show a dark ring at the distal ends 
of femur, patella, tibia, metatarsus and tarsus, as well as a ring at the proximal end and 
middle of the tibia. 

The ground color of the abdomen is creamy white, some specimens showing a light tan 
to olive-green hue toward the sides. There are two rows of black spots extending along the 
dorsum, four to six spots in each row. Between these two rows many specimens show two 
rows of very narrow lineate black spots, sometimes only on the anterior half. On the 
ventral side one can see two black spots on either side of the spinnerets. Between the 
epigastric furrow and the base of the spinnerets is a more or less rectangular yellow area 
where the hourglass mark will appear in later instars. At this stage it is barely pinched in at 
the middle. 



1970 



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65 











Figure 18. Postembryonic developmental stages of i. hesperus. a, first instar, dorsal aspect; b, the same, ventral 
aspect; c, second instar, dorsal aspect; d, the same, ventral aspect; e, third instar, dorsal aspect; f, the same, 
ventral aspect; g, fourth instar, dorsal aspect; h, the same, ventral aspect; i, fifth instar, ventral aspect. 



SECOND INSTAR (Figs. 18c, d). — The dark lines on the carapace have become a trifle 
wider and the legs a bit darker, with leg III beginning to show annuli like the others. The 
greatest amount of change is on the abdominal dorsum where there is a suffusing of gray 
pigment on the sides of the dorsum that extends down laterally. In some specimens the 
black spots are larger than they were in the previous instar, but in others they have become 
incorporated into two faintly discernible olive bands. A similarly colored band begins to 
appear encircling the dorsum up front. 

THIRD INSTAR (Figs. 18e, 0- — On the carapace the marginal dark bands have widened. 
The marginal dark bands of the sternum have become wider than the median yellow area. 



66 



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VOL. 16 









Figure 19. Postembryonic developmental stages of L. hesperus. a, sixth instar female, dorsal aspect of a dark 
specimen from El Centro, California; b, the same specimen, ventral aspect; c, sixth instar female, dorsal aspect of 
a light specimen from Riverside, California; d, fifth instar female, dorsal aspect; e, fourth instar, penultimate 
male, dorsal aspect; f, the same, ventral aspect. 

The dorsum now distinctly shows the pair of longitudinal bands, olive gray, one on either 
side of the midline, with a branch on each side from the anterior end and another such 
branch from just behind the middle. Each of these branches extends diagonally back to the 
side. The anterior encircling band is now more pronounced, so that from the side one now 
sees these bands extending down obliquely to the rear. Besides these there is the band 
extending straight back, closer to, and parallel to, the midline. Thus there are three light 
areas on each side, as well as the median one. In many specimens a little orange pigment 
begins to form along the center of this median one. There are still remnants of the original 
black spots, though these are now blended in with the olive gray bands. In the texanus 
variety these latter bands are often pink. On the venter the two black spots on either side of 
the spinnerets are quite conspicuous. The hourglass mark now shows tinges of orange, and 
to each side of it a black line has developed. 

FOURTH INSTAR (Figs. 18g, h). — There is a light variety, members of which are hardly 
distinguishable from the third instar. Often males are recognizable now as in the 
penultimate instar (see below) and they are usually of the light variety (Figs. 19e, 0- For 
the dark variety one notes that on the sternum and carapace the areas covered by the black 
bands have enlarged, and the median band of the carapace has widened behind. 

The abdominal dorsum now shows the pattern of bands much more distinct, with 
more gray mixed in with the olive and usually with somewhat more orange pigment along 
the midline. In some specimens the light areas between the bands show some orange 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 67 

pigment, and the bands are brownish gray. The hourglass mark shows a Httle more orange 
pigment along its middle. 

Some males mature in this instar. 

FIFTH INSTAR (Figs. 18i, 19d). — The carapace is not much different from that in the 
fourth instar, though the sternum shows the light central area still further reduced. The legs 
still show some of the annuli faintly, but they are getting darker, and on the tibiae the 
central and distal rings have come together to form one large ring. On the abdominal 
dorsum the dark bands are wider, so that now the median light stripe is narrower than they 
are. For the dorsum as a whole there is a much larger surface covered by the gray bands 
than by the light areas. The gray areas are outlined in black. A row of orange spots now 
appears in the median light stripe. The orange pigment in the hourglass mark is deeper in 
the front and back halves, with hardly any in the central portion. 

Some males mature in this instar; and those maturing later seem nevertheless to retain 
the markings of this fifth instar. They hardly change although a few seem to get a little 
darker. I have examined many specimens that matured in this, in the sixth, and in the 
seventh instars, and contrary to ideas I formerly held I was unable to note any significant 
differences in their appearance. 

SIXTH INSTAR (Figs. 19a, b, c). — The darker specimens show more pigment on the 
carapace and have the dark areas more extensive than previously. There remains on the 
sternum only a narrow central light band. On the legs the dark areas have increased in size. 

The abdominal dorsum is mostly covered with dark pigment now, with the only light 
areas reduced to a basal transverse band, a row of spots along the midline, and two pairs of 
diagonal stripes extending down the sides to the rear. These latter are the areas that had 
previously been wide, between the dark areas that had previously been narrow. Each of the 
light spots along the midline encloses a reddish spot. The hourglass mark is becoming more 
constricted at the middle and has more red pigment. 

Some individuals, showing a more or less similar arrangement of spots, have the 
pigmented areas lighter. Also, the light diagonal bands extend farther down on the sides, 
and the dorsal spots are more orange than red. 

SEVENTH, EIGHTH AND NINTH INSTARS. — Most females mature in these instars. While 
I had previously supposed that those maturing in the later instars would show more of the 
black pigment, and smaller areas of light pigment a comparison of many specimens 
revealed that (as was the case with the mature males) there is no significant difference in 
their appearance. A female maturing in the seventh instar may look quite similar to one 
maturing in the ninth. This, of course, does not preclude the possibility of changes 
occurring during the instar. Some males mature in the sixth and seventh instars, and in 
general they resemble a female in the fifth or sixth, of the light variety. Some males are 
darker. The legs retain the annuli, which are often more conspicuous than those in young 
females, and often without the fusion of middle and proximal rings on the tibiae. 

Latrodectus variolus 

FIRST INSTAR (Figs. 20a, b). — The carapace is reddish orange to brownish orange, with 
the eye region black. The median and marginal dark bands so noticeable in the other two 
species are lacking. The sternum is about the same color with the margins somewhat 
dusky. The legs show the same ground color as the carapace, but there are faintly indicated 
annuli. These appear on legs I, II, and IV at the distal ends of patella, tibia and metatarsus, 
with those on leg I slightly darker. Leg III is hke leg I but the annulus is absent from the 
metatarsus. 



68 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

The ground color of the abdomen is reddish orange. There is a large black area around 
the spinnerets and anal tubercle, and there are three pairs of large black spots on the 
dorsum. The dorsum has white blotches along the middle, and some white extending to the 
sides in front of each black spot. Where the abdomen overhangs the carapace is a white 
transverse band, which extends diagonally to the rear on each side to a pair of white spots 
farther back. There are three pairs of diagonal white bands. The hourglass mark is not 
distinct, but some specimens have irregular white blotches in this area. 

SECOND INSTAR (Figs. 20c, d, e, f)- — This is very similar to the first instar, with the 
carapace somewhat browner, the black spots on the abdominal dorsum a bit larger, and the 
hourglass mark showing more white as "cottage cheese" blotches. 

THIRD INSTAR (Figs. 20g, h). — The carapace is now more chestnut brown. The legs 
appear dull orange to chestnut brown, and the annuli are slightly darker. On leg I the basal 
half of the femur is dark, as are also the distal half of the patella, the distal third of the 
tibia, and the distal fourth of the metatarsus and tarsus. 

The greatest change is seen on the abdomen, which is now black over most of the 
dorsum. There remain a white band across the front, a median row of white spots, and 
three pairs of diagonal white bands extending down the sides, so that their lower ends are 
visible from the ventral aspect. In each median spot is a small spot of orange-red pigment. 
The hourglass mark is complete, but relatively faint in the middle area. 

Specimens that have recently molted to the third instar often show the black area 
brownish instead, except for those places where the original six black spots were. But the 
black pigment suffuses into these brown areas so that later in this stage a larger area looks 
black. 

FOURTH INSTAR (Figs. 20i, j). — The general appearance is much like the third instar. 
The carapace and legs, however, are more dusky. On the abdominal dorsum the spots of 
the median row are now red. The basal band and the lateral oblique white bands are 
narrower and shorter, so that the laterals no longer extend to the ventral side. The 
hourglass mark is now red, and in most specimens shows a distinct separation into two 
parts. 

FIFTH INSTAR (Figs. 20k, 1). — The spiderlings look much like those of the preceding 
instar, but with the carapace and legs darker. The annuli still show on the latter. The 
abdominal dorsum has the light areas still further reduced. Nearly all specimens show the 
hourglass mark divided. 

SIXTH INSTAR. — The carapace and legs are dark brown to black, and the leg annuli show 
plainly. Some males mature in this stage. 

SEVENTH, EIGHTH AND NINTH INSTARS. — Females mature in these stages. Illustra- 
tions of this species have been published by Judd (1965), Wilson (1967) and, under the 
name L. mactans, by Emerton (1902) and Kaston (1937a, 1948, and 1953). 

APOSEMATIC COLORATION 

One can see from the above descriptions how different the spiderlings are from the 
adults. These changes, as the spiderlings grow and molt, were first noted by Duges (1836) 
for L. tredecimguttatus. Duges, and also Marikovskii (1947) pointed out how the many 
different appearances could be responsible for authors describing each stage as a different 
species, and this, in part, accounts for the long list of synonyms. 

Apropos of the changes in color as the spiderlings develop, it should be noted that all 
three of our North American species acquire more black pigment, and that the hourglass 



1970 



KASTON: AMERICAN BLACK WIDOW SPIDERS 



69 















Figure 20. Postembryonic developmental stages of L. variolas, a, first instar, dorsal aspect; b, the same, ventral 
aspect; c, second instar, dorsal aspect; d, the same, ventral aspect; e, second instar, variation, dorsal aspect; f, the 
same, ventral aspect; g, third instar, dorsal aspect; h, the same, ventral aspect; i, fourth instar, dorsal aspect; j, the 
same, ventral aspect; k. fifth instar, dorsal aspect; 1, the same, ventral aspect. 

mark on the venter becomes more prominent and a deeper red. Bristowe (1945, 1946) 
considered this red mark an indication of aposematic coloration for the spider, presumably 
present in the older females only and not in females younger than the sixth instar, nor in 
males (which he considered as maturing in the sixth). From his illustrations of the first and 
second instar spiderlings, it is clear that he was referring to L. hesperus, not to L. mactans. 
Yet, in L. hesperus the hourglass mark is quite clearly developed already in the third instar, 
becomes impregnated with orange pigment (and even with red in some specimens) in the 
fourth, and is quite definitely present in males, even if these mature in the fourth or fifth 



70 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 








Figure 21. a, Z,. hesperus female from California, with egg sac; b, L. Hesperus female from Arizona making egg 
sac; note ball of eggs through semitransparent unfinished sac; c, on left, the egg sac and newly emerged spiderlings 
of L. maclans: on right, the same of L. hesperus. 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 71 

instar. 

In L. variolus the hourglass mark may appear more "complete" in the young, and 
usually loses its middle portion in later instars. This has been reported also by Marikovskii 
(1947) for L. tredecimguttatus. Likewise, for L. indistinctus Smithers (1944) has shown 
that an hourglass mark is present in the spiderlings but disappears completely (or almost 
so) by adulthood. According to Beregovoi (1962), L. pallidus has no hourglass mark in any 
of its stages. Despite Bristowe's remark that L. geometricus differs from other members of 
the genus in not having the hourglass mark, all specimens from Florida and the West 
Indies that I have seen do possess this mark, and Smithers has observed it in South African 
members of this species. Moreover, this species has been known to cause envenomation in 
humans (Finlayson, 1956). Contrary to Bristowe's supposition, it has been known for 
many years that young individuals and males do have poison, albeit less than mature 
females. Moreover, even those species without a distinct hourglass may have virulent 
venom, and may be much feared. 

RATE OF DEVELOPMENT AND LONGEVITY 

Several observers have supplied information as to the number of molts and the length 
of time to maturity. Studying the ctenid Cupiennius salei, Melchers (1963) found that 
poorly fed spiderlings matured after fewer molts. Contrariwise, Miyashita (1968) for 
Lycosa T-insignata, and Deevey (1945, 1949) for Latrodectus mactans found that those 
poorly fed required more molts. Well fed spiderlings not only underwent fewer molts but 
matured in a shorter time. But of course feeding is not the sole factor, and as indicated, 
wide variations occur even among siblings in the same family when raised under identical 
conditions. 

Even under uniform environmental conditions, there was considerable variation with 
respect to the number of molts, the intervals between molts, and the length of time it took 
for the spiders to mature. This variability extended even to "litter-mates'" from the same 
egg sac, and is similar to that found by Deevey (1949), and by Witt and Reed (1965). For 
example, there is the case of three sisters maturing on the same day, 100 days after 
emergence, L. mactans #1132-A-51 in the sixth instar, #1132-A-57 in the seventh, and 
#1132-A-59 in the eighth. Sometimes a particular family shows a faster or slower 
development, or in some other way is different from the average, e.g., some of the L. 
variolus families had all the males ready to mature in the sixth instar, but in other families 
it was the seventh instar. By far the greater majority of spiderlings failed to mature. This 
was especially the case with specimens of L. variolus, which appear to require a longer 
time, and most often a greater number of molts than do the other two species. Most of 
them died in the fourth or fifth instar. 

More success was obtained with males than with females, probably in part because 
males go through fewer instars on the average, and mature earlier. Thus I am unable to 
understand the remark by Baerg (1923) that males (of Arkansas L. mactans) were more 
difficult to rear than females, nor the statement by Knowlton (1935) that males (of L. 
hesperus in Utah) required a longer time to mature than did females. 

For what is undoubtedly L. hesperus, data were given by Herms et al. (1935), 
ChamberHn and Ivie (1935), Knowlton (1935), and Bhatnagar and Rempel (1962). For L. 
mactans proper, data were given by Lawson (1933), Blair (1934), Muma (1944), Deevey 
(1945, 1949) and McCrone and Levi (1964). The latter also compared the development of 
L. mactans with that of L. variolus. For exotic species Smithers (1944) reported for L. 
indistinctus; Bonnet (1938) and Baerg (1954) for L. geometricus. For L. tredecimguttatus 
data were given by Juberthie (1954), Shulov (1940) and Marikovskii (1947); and for L. 



72 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

pallidus by Shulov (1940) and by Beregovoi (1962). 

Table 2 shows that the number of instars passed through to maturity is quite variable, 
and about equally variable for L. mactans and L. hespenis. However, for both sexes, with 
individuals undergoing the same number of molts, development is somewhat more rapid in 
L. mactans. Also, although females of both species mature in the sixth through ninth 
instars, more of the L. mactans reach maturity in the sixth and seventh (mode is seventh), 
while more of the L. hesperus mature in the eighth or ninth (mode is eighth). The difference 
between them, however, is not nearly as great as that found by McCrone and Levi (1964) 
between L. mactans and L. variolus. Because of my poor success with rearing of L. variolus, 
only relatively few data can be supplied, and these for males primarily. Therefore, for 
comparison, I am including in Table 3 data about this species from McCrone and Levi, but 
have rearranged the data to conform to the way these are presented in Table 1. Although I 
had no males of L. hesperus maturing in the eighth instar, two penultimate males from 
California died in their seventh, and would therefore, had they lived, have matured in the 
eighth. Also, besides those shown in the table, one L. mactans and three L. hesperus 
females died as penultimates in the eighth instar, and would therefore have matured in the 
ninth instar had they lived.' 

Table 2 shows that for males there is likewise a wide spread of instars, with the fifth 
the mode in both species. It would appear that the shortest time in which a male can 
mature is 37 days. However, among L. hesperus families for which the records are 
incomplete, were one Arizona family, and one from British Columbia, in which males 
matured in 33 days, and a family from Texas in which several males matured in 27 and 28 
days. Likewise, although from the table, 177 appears as the longest interval in days to 
maturity for a L. mactans male and 263 days for a L. mactans female, I have records of 

Table 2. Rate of development of L. mactans and L. hesperus. 





Instar 
in which 
Sex Matured 


Number of 
Individuals 


Number of days spent in each 


instar 


No. of days to 
Range Mean 


Maturity 
S.D. 


Species 


1 


2 


3 


4 


5 


6 


7 8 






4 


16 


13.6 


13.5 


28.8 










37-139 


61.6 


±42.4 




Male 


5 


140 


13.9 


11.6 


19.0 


48.0 








40-196 


99.0 


±29.0 


S 




6 


88 


14.9 


10.7 


12.6 


24.5 


42.3 






46-210 


119.3 


±49.0 






7 


6 


17.0 


10.5 


11.0 


21.0 


53.5 


27.5 




61-214 


150.6 


±73.5 






6 


5 


9.6 


8.6 


12.0 


26.8 


70.2 






73-185 


137.1 


±42.4 


'-I 




7 


22 


11.8 


10.0 


11.5 


29.5 


58.3 


26.8 




75-239 


146.9 


±38.7 1 






8 


49 


12.4 


10.3 


11.3 


22.9 


48.9 


36.8 


26.6 


74-325 


202.3 


±63.9 ! 






9 


12 


11.7 


10.6 


14.7 


38.0 


68.2 


50.9 


28.6 29.4 


102-325 


242.0 


±81.8 






4 


13 


16.3 


13.7 


24.2 










49-84 


54.4 


± 9.2 






5 


82 


12.9 


10.7 


13.4 


26.1 








38-138 


63.7 


±11.8 




Male 


6 


48 


13.4 


9.5 


11.9 


22.3 


32.3 






49-161 


84.3 


±16.9 


s 




7 


14 


10.6 


9.1 


12.7 


13.0 


28.8 


28.6 




74-177 


87.7 


±42.4 


a 




8 


1 


11 


12 


9 


6 


14 


97 


17 


— 


166 


— 


5 




6 


11 


16.6 


10.6 


13.0 


24.4 


35.9 






62-134 


111.7 


±18.1 


'J 




7 


23 


12.6 


8.6 


14.9 


15.0 


33.3 


31.8 




64-193 


137.9 


±41.2 






8 


13 


11.0 


8.9 


10.7 


19.5 


53.4 


34.0 


23.8 


97-263 


140.5 


±85.4 






9 


1 


7 


14 


9 


12 


24 


16 


7 18 


— 


107 






























1 



While this manuscript was in press a female L. mactans. #1647-A-1 19, matured in the tenth instar, 190 days 
after emergence. 



1970 



KASTON: AMERICAN BLACK WIDOW SPIDERS 



73 



194 for a male and 378 for a female from North Carolina. 

Table 3 shows that spiderlings of L. variolus spend a much shorter time in the first 
instar than do spiderlings of the other two species. Table 4 shows that the minimum 
number of days spent in a given instar tends to increase as the spiderlings get older. For the 
maximum number of days in a given instar I am unable to find any correlation. 



Table 3. Rate of development of L. variolus. 



Sex 


Instar in which 

would have 

matured 


No. of 
Ind. 




Mean num 


ber of days spent 


in each instar 








I 


II 


III 


IV 


V 


VI VII 


VIII 








5 


10 


9.8 


12.3 


24.0 












Male 




6 


75 


4.8 


11.3 


13.3 


21.9 














7 


5 


5.1 


14.6 


12.2 


18.2 


19.2 












8 


2 


4.5 


18.5 


12.0 


15.0 


15.0 


12.0 










6 


3 


4.0 


8.3 


9.3 


19.7 










Female 




7 


4 


3.5 


6.5 


11.5 


17.0 


38.8 












8 


3 


4.5 


17.5 


11.5 


18.5 


11.5 


26.5 







Instar in 

which 
matured 



Data below have been taken from McCrone and Levi (1964). 



No. of 

days to 

maturity 





6 


1 


6 


12 


11 


15 


87 








131 


Male 


7 


9 


5.1 


15.1 


11.8 


13.4 


32.6 


49.4 






129.4 




8 


12 


5.2 


16.5 


12.3 


10.7 


14.1 


31.6 


38.3 




129.7 


Female 


8 


18 


6.4 


13.8 


10.1 


13.4 


22.6 


41.9 


43.2 




152.4 




9 


4 


6.3 


12.0 


9.2 


14.0 


14.8 


25.2 


38.5 


33.5 


153.5 



Table 4. Minimum and maximum number of days spent in each instar. 











Instar 












I 


II 


III 


IV 


V 


VI 


VII 


VIII 


L. Hesperus 1 


49 


3; 52 


3; 190 


5; 147 


6: 200 


7; 126 


11; 99 


15; 53 


L. mac tans 1 


57 


4; 55 


4; 112 


5; 143 


7: 138 


10; 97 


7; 75 




L. variolus 1 


33 


5; 30 


6; 48 


6; 76 


7; 76124 









Table 5 shows that in both sexes L. hesperus on the average lives longer than L. 
mactans after becoming mature; for females about one and one-third times and for males 
about twice as long. Likewise the total life span from the time of emergence is longer, again 
by more than one and one-third times in females, and about one and one-half times in 
males. Table 6 shows the maximum number of days that any specimen lived after 
maturing, and the maximum number for the entire life span after emergence. The female 
of/., mactans which lived 849 days after maturing must have been older than the 858 days, 
which is the maximum I have noted for another individual. Adding to 849 the 62 days 



74 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Table 5. Life span. 



Species 


Sex 


Number of 
individuals 


Mean 

number of days 

post-maturity 


Number of 
individuals 


Mean 

number of days; 

emergence to death 


L. Hesperus 


Male 


255 


46.5 ± 34.6 


240 


146.1 ± 51.0 


Female 


144 


277.5 ± 152.6 


87 


481.0 ± 199.5 


L. mactans 


Male 


158 


21.1 ± 12.6 


149 


90.8 ± 24.0 


Female 


62 


203.1 ± 141.4 


44 


369.6 ± 149.0 



found minimal for L. mactans females to mature, one obtains for this particular individual 
a life span of at least 9 1 1 days. 

The longevity of Z,. hesperus and of/,, variolus thus is greater than that of I. mactans. 
To ascertain whether this hardiness was also a feature of the young, I set out a family of 
each species right after emergence and kept them without food. Shulov (1940) had found 
that newly emerged L. pallidus spiderUngs can live up to 19 days without food. Also, that 
the spiderlings of L. tredecimguttatus can molt to the second instar without their having 
fed. 

My three families included 213 newly emerged spiderlings of/,, mactans (from egg sac 
1377-A collected in Arkansas), 200 spiderlings of L. hesperus (from egg sac #1352-B 
collected in California), and 128 spiderlings of/,, variolus (from egg sac # 1381 -A collected 
in Missouri). From the L. mactans family, the first spiderling died two days after 
emergence, the last 16 days later. The largest number ( = 54) died on the seventh day after 
emergence, when a little over one-half their number had died. None had molted to the 
second instar. From the /,. hesperus family, the first to die survived 8 days, the last 32 days. 
The largest number ( = 28) died 19 days after emergence, when a little over one-half their 
number had died. Fifteen of them had molted to the second instar, one within a day after 
emergence and two 10 days after emergence. Those which attained the second instar died 
from the 19th to the 24th day after emergence. From the /,. variolus family 36 died the day 
after emergence, but one survived 37 days. The largest number ( = 8) to die after the second 
day succumbed 19 days after emergence, when a little over half had died. Eighteen molted; 
two of them two days after emergence, and two on the eleventh day after emergence. Those 
which attained the second instar died from the 1 2th to the 3 1 st day after emergence. Thus it 
would appear that L. variolus shows the greatest longevity and hardiness, and L. mactans 
the least. 

MOLTING 

I often saw spiders in the act of molting, but only once was I able to observe the entire 



Table 6. Maximum longevity: in days. 





L. 


hesperus 


L. 


mactans 


L. 


variolus 




Male 


Female 


Male 


Female 


Male 


Female 


Number of days 
post-maturity 


196 


952 


127 


849 


155 


822 


Number of days 
post emergence 


369 


1049 


235 


858 
(911)* 




1063 



*See text for explanation 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 75 

process from the beginning. The specimen was a female L. mactans #1 186, molting from 
the penultimate instar to maturity. In all essentials the process closely resembled that 
described for L. Hesperus by Hagstrum (1968). 

The spider assumes a position with spinnerets attached to a thread overhead and all 
legs fully extended, hanging from above. There is slow rhythmic up and down movement of 
the body, and the carapace splits around its edges. In about five minutes the old carapace 
comes off from the cephalothorax. During the next half hour the legs are extricated from 
the old skin, and the abdomen likewise slowly emerges, with the old skin being pushed 
toward the spinnerets. The shortest legs, II and III, emerge first, and the anterior legs last. 
When the legs are all out of the old skin, the spider extends them horizontally, and holds 
them in that position for a while. The entire process took about 30 minutes. The old 
exuviae are cut out of the web some hours or even days later. 

While ordinarily the molt to maturity is the final one, several exceptions have been 
encountered, and an account has already been published by Kaston (1968), of five instances 
of post-maturity molting. One additional case can be added here. A mature female L. 
hesperus #1336 which was collected in San Diego, California, on February 16, 1968 
molted, on March 8, 1968. 

SEX RATIO 

Montgomery (1908) supposed that he could sex spiderlings upon their emergence 
from the egg sac. He took the newly emerged young with high, wide abdomens to be 
females, those with low and narrow abdomens to be males. On this basis he obtained a 
ratio of 8. 1 males to 1 .0 females. He did not rear the spiderlings to verify his prediction. 

I too have observed that among the emerging spiderlings some have stout high 
abdomens, and others had abdomens perhaps half as high and half as wide; but there were 
also some of intermediate size and form. For one large family of/,, mactans from Florida, 
# 1005-A, the shape and size was noted for each spiderling that emerged. The development 
was followed, and the sex ascertained when old enough. Both males and females developed 
from the spiderlings that had the large abdomens, small abdomens, and intermediate 
abdomens, so no correlation could be made. 

Bonnet (1938) raised a small family of L. geometricus and obtained about twice as 
many males as females. However, Bouillon (1958) working with the same species, but a 
much larger sample size, found a slightly greater number of females than males. His 
statistical analysis indicated that the results were consistent with a ratio of 1:1. Likewise 
Deevey (1949) obtained a 1:1 ratio in L. mactans; Herms et al. (1935) had found this to be 
the case in L. hesperus, and McCrone and Levi (1964) Hkewise obtained this ratio for both 
L. variolus and L. mactans. 

In my studies the majority of specimens maturing were male. Deevey indicated that 
when the spiderlings were underfed a higher percentage of males matured. This might 
possibly be the explanation for some of my results with many spiderlings dying before their 
sex could be ascertained. However, in about half of the families raised in all three species, 
the ratios obtained were consistent with the hypothesis of a 1:1 ratio when a chi square 
analysis at the 5% level of significance was made. 

HABITAT AND WEB STRUCTURE 

Most members of the genus Latrodectus build their webs close to the ground. 
However, L. bishopi builds above ground in palmetto shrubs, and Abalos and Baez (1967) 
reported their Latrodectus # 1 as never having been found less than a meter above ground. 
They also indicated that L. geometricus seems to prefer human habitations, and this had 



76 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

been noted as well by Smithers (1944) and by Lamoral (1968). McCrone and Levi (1964) 
found L. variolus in northwestern Florida high off the ground in trees, but this species in the 
more northern parts of its range (at least in Arkansas, Missouri, Illinois, Kansas, 
Michigan, and Connecticut) will be found in leaf litter on the ground in mesic to xeric 
deciduous forests. Fitch (1963) in Kansas, and I in Connecticut have also seen this species 
under stones, and in Michigan it has been found under logs, under fence posts, and in the 
holes made by small mammals in the ground (Wilson, 1967). It may well be, as suggested 
by Bhatnagar and Rempel (1962) that sympatric populations "tend to differ in their 
habitat, but the allopatric populations [ of L. mactans and L. variolus] may occur in 
identical habitats." 

The webs of L. hesperus have been reported similarly from holes of small mammals 
(Jellison and Philip, 1935), in other holes of uneven ground, and along roadsides, etc., but 
also at times in trash, in sheds, sometimes six or more feet above ground level, and along 
the outside of houses close to the ground level. At times the density of individuals may be 
quite high where suitable hiding places exist. For example, in one weedy, litter-filled lot in 
Brawley, California, 100 specimens, adult or nearly so, were obtained in a couple of hours 
collecting, in an area of 120 by 150 feet. 

The female is negatively phototropic and generally hangs in an inverted position under 
a piece of overhanging board, or clod of earth, or back in her retreat. Thus she is usually 
not visible during daylight hours. But after dark the spider may move out over the snare, 
taking a position perhaps several inches in front of the overhang. 

Latrodectus mactans has been reported in Louisiana (Gowanlock and Leeper, 1935) 
and in Maryland (Muma, 1944) from relatively dry situations in piles of stones, in culverts, 
fence corners, under steps, in burrows of animals, in housings of service meters, etc. I 
myself have found this species in and around human habitations, in tobacco barns in North 
Carolina, and corners of rooms and basements in Georgia. 

Specimens may be found throughout most of the year, though in those regions with 
cold winters the spider remains inactive in a retreat under a stone, etc. Since females quite 
often live more than one year, it would be expected that mature females can be found at 
any season. On the other hand, males, which have a shorter life, are found mature mainly 
during the warmer months. I have records of L. variolus males being taken in April and 
May; of L. mactans males from May through October; and of L. hesperus males from 
March through October, with the majority in August and September. 

As indicated previously, the webs of black widows are of the irregular mesh type. 
Nevertheless, the webs are not lacking in organization. They have been extensively studied 
by Szlep (1965, 1967) and also by Lamoral (1968). In all three of our species the spider 
builds a retreat, or refuge, which in nature would be under a clod of dirt or other 
overhanging protective structure. 

In L. hesperus the retreat has a horizontal upper border, and a curved lower border, 
and leads through a tunnel an inch or so in diameter to a catching sheet. This latter is 
usually horizontal, or only slightly inclined. Above the sheet is a loosely woven upper and 
outer portion. Below the sheet are a number of oblique and vertical threads connected to 
the substratum. These threads are of the "gum-footed" type, with viscid globules arranged 
for the most part along the lowest three to five mm, but occasionally extending up as much 
as 30 mm. These viscid globules are usually absent from the middle layer, the catching 
sheet, and always absent from the retreat itself. While the webs are usually a foot or so 
across, and equally as high, they can be larger. One web in an unused wooden shed had a 
catching portion about 30 inches above the ground level, with threads extending to a retreat 
in the rafters about 12 feet above the ground. 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 77 

In L. mactans the retreat is globular and quite dense, and Gaul (1949) noted that it 
was never in actual contact with the ground. The middle layer is not as well defined as in L. 
hesperus, and there are many polygons formed by the crossing threads below the layer. The 
"gum-footed" threads are lacking, or almost so, but there may be some viscid droplets on 
the middle layer itself. 

Lamoral (1968) indicated that he had observed "gum-footed" threads in webs of L. 
mactans. But he was basing the determination of the species (in South Africa) on Levi's 
having synonomized L. indistinctus. This difference in the nature of the webs could be one 
of the valid reasons for maintaining L. indistinctus separate from L. mactans. 

In L. variolus the retreat is dome-shaped, but larger than in L. mactans. The middle 
layer is much more extensive than in the other two species, and is provided with some viscid 
globules. There are fewer "gum-footed" threads extending to the substratum, than is the 
case in L. hesperus. 

FOOD AND FEEDING HABITS 

Black widow spiders will attack and eat almost any insect that wanders into the snare. 
Depending upon whether the web is relatively close to the ground, or higher up, there will 
be a larger percentage of crawling or flying forms. 

Shulov (1967) reported L. pallidus subsisting more on ants, while he noted that L. 
tredecimguttatus consumes tenebrionid beetles, crickets, grasshoppers, and bugs. 
McCrone and Levi (1964), finding that webs of L. bishopi are generally free of insect 
remains, suggested that this species feeds only on soft-bodied insects. Even if such were the 
case the corpses would still be adorning the web for at least a short time, since the spiders 
would merely digest out the non-cuticular portions of the prey. The other alternative they 
proposed would appear to be more likely; that is, the spider ejects the remains from the 
web sooner than do the other species. 

Occasionally, there will be found, suspended by the very strong threads of the web, 
animals other than insects, and L. hasselti has been reported catching centipedes and 
snakes. Roberts (1941) suppHes a photo of a female L. hasselti feeding on two lizards which 
were ensnared. McKeown (1943) repeats this account, and also supplies an account, with 
illustrations, of an instance where a mouse was the victim. For an itemized list of the prey 
species taken by L. hesperus see Exline and Hatch (1934). 

According to many reports in the literature once the male matures, he eats little, or 
not at all. I did not find this always to be the case. Many males ordinarily caught and ate 
prey until very near the end of their life span. It is well known that spiders generally can 
endure long periods of fasting. To get some idea as to the capabiUty of black widows in 
this regard, 37 femals of L. hesperus were kept without food from the day of their molting 
to maturity. The one to succumb soonest died in 36 days; the hardiest lived for 193 days. 
Eleven individuals lived over 100 days, and the mean longevity was 89. 3± 12.8 days. 

PARASITES AND OTHER ENEMIES 

A number of egg sacs collected in the field proved to contain dipterous parasites 
within; except for one from Texas, they were from various California localities. This 
parasite, the chloropid, Pseudogaurax signata (Loew), (Figs. 16c, d), is really an egg 
predator, and has a sparse distribution (Pierce 1942). Even when a sac is parasitized the 
ratio of emerging spiderlings to parasitic flies is 5:1. Details on its life history and 
development were given by Kaston and Jenks (1937). 

Of the hymenopters parasitizing egg sacs, Shulov (1940) reported for L. tredecimgut- 
tatus a Eurytoma sp. and Abalos and Baez (1967) reported for L. mactans a eulophid. But 



78 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

the hymenopterous parasite about which most is known is the sceHonid, Baeus latrodecti 
Dozier, reported by Pierce (1942) from the egg sacs of L. hesperus in CaHfornia. Also, 
from sacs of the latter species Herms et al. (1935) reared the egg predator Gelis sp., an 
ichneumonid. 

As for the predators, one notices in the laboratory occasional instances of a 
mealworm, Tenebrio molitor, eating a black widow. Probably this is managed when the 
spider is molting (Deevey, 1949), or else moribund, and thus helpless to defend itself. 
Pierce (1942) and Branch (1943) for L. hesperus, and Archer (1947) for L. mactans, have 
observed that black widow spiders are eaten by the related theridiid spider, Steatoda grossa 
(C. L. Koch). Archer also noted that the pirate spider, Mimetus sp. attacked L. mactans in 
Alabama, and I have seen Mimetus hesperus Chamberlin feeding on L. hesperus in 
California. 

Cowles (1937) considered that the San Diego alligator lizard was an effective 
predator, but, as pointed out by Irving and Hinman (1935) perhaps the most effective, and 
certainly the most wide-spread predator, is the blue mud-daubing wasp, Chalvbion 
californicum (Saussure). Rau (1935) had observed in Missouri that this wasp preferentially 
provisions its mud cells with L. mactans rather than with other spiders. D' Amour et al. 
(1936) had noted the same for L. hesperus in Colorado, and I have observed the same for 
L. mactans in Georgia, as well as for L. variolus in Connecticut. 

ACKNOWLEDGMENTS 

These studies were carried out with the aid of a National Institutes of Health grant No. GM 14623, and a 
faculty grant-in-aid from the San Diego State College Foundation, both here gratefully acknowledged. I extend 
thanks to those who helped me obtain live specimens from the following States and Provinces: from Alberta, P. E. 
Blakely; Alabama, J. D. Unzicker; Arizona, V. D. Roth, F. E. Russell, and W. J. Gertsch; Arkansas, Maxine 
Hite; Baja California, J. Y. Sandoval; British Columbia, E. Thorn, and L. C. Curtis; California, M. H. Stewart, 
M. E. Thompson. F. E. Russell, and M. H. Stetson; Florida, J. F. Anderson, J. A. Beatty, and J. D. McCrone; 
Georgia, J. R. Gorham and B. M. Furlow; Illinois, J. M. Nelson; Kansas, D. E. Gates; Louisiana, K. W. 
McCain; Michigan, L. A. Wilson; Mississippi, L. R. Roddy; Missouri, H. E. Frizzell, and W. C. Peck; North 
Carolina, J. J. Moore; New Jersey, R. C. Kern; New York, Arthur Bordes; Ohio, C. Oehler; Oklahoma, John 
Taylor; Oregon, J. Anderson; Tennessee, B. C. Moulder; Texas. B. R. Vogel, and R. W. Mitchell; Virginia, R. E. 
Ailstock, and J. E. Carico; Washington, Wyatt Cone; and West Verginia, W. Shear. The drawings were done 
chiefly by M. H. Stewart and B. R. Burnett. I was able to see the types of L. hesperus through the kindness of Dr. 
W. J. Gertsch. I owe thanks to Professor L. A. Fetzer for the translation of Russian hterature, and to Steve Sitko, 
Joseph Y. Sandoval, and Bruce A. Richardson for their technical assistance. 

LITERATURE CITED' 
Abalos.J. W. 

1962. The egg sac in the identification of species of Lalrodectus. Psyche 69:268-270. 
Abalos, J. W. and E. C. Baez 

1963. On spermatic transmission in spiders, /bid. 70: 197-207. 

1967. The spider genus Latrodectus in Santiago dell Estero. Argentina. In, Animal Toxins, New York, 
Pergamon Press, p. 59-74. 
Archer. A. F. 

1947. The Theridiidae or comb-footed spiders of Alabama. Alabama Mus. Nat. Hist., Paper no. 22:5-67. 
Bacetti, B.. R, Dallai and F. Rosati 

1970. The spermatozoon of Arthropoda. VIII. The 9 + 3 flagellum of spider sperm cells. J. Cell Biol. 
44:681-682. 



'A book about black widow spiders often cited is that by R. W. Thorp and W. D. Woodson. 1945, 
Black Widow, America's most poisonous spider. Chapel Hill. University of North Carolina Press. 220 
p. While it is true that it does give much information, all of it gleaned from the observations of others, 
numerous errors and contradictions are included. The authors are entirely without scientific training, 
and for various phenomena concerning black widows have supplied peculiar interpretations, some 
quite teleotogical. 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 79 

Baerg, W. J. 

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1954. The brown widow and black widow spiders in Jamaica. Ann. Entomol. Soc. America 47:52-60. 

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Blair, A. W. 

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Bonnet, P. 

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Leopoldville. No. 1, 22 p. 
1957b. Les fonctions du cocon chez I'araignee Latrodectus geometricus C. Koch. Ibid. No. 2, 30 p. 

1958. La sex-ratio chez I'araigne'e Latrodectus geometricus C. Koch. Ibid. No. 3, 8 p. 
Bouillon, A. and R. Lekie 

1 96 1 . Cycle and rhythm in the ovulation of the spider Latrodectus geometricus. Nature 1 9 1 :620-62 1 . 
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1945. (Review of "Black Widow" by Thorp and Woodson). Entomol. Monthly Mag. 81:xxxix-xl. 

1946. Some notes about the American black widow spider, Latrodectus mactans F. Ibid. 82:54. 
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1935. A review of the biology and distribution of the hourglass spider. J. Kansas Entomol. Soc, 8:1 17-130. 
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1935. The black widow spider and its variations in the United States. Bull. Univ. Utah 25(8): Biol. Ser. 
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Cowles, R. B. 

1937. The San Diegan alligator lizard and the black widow spider. Science 85:99-100. 
D'Amour, F. E., F. E. Becker and W. Van Riper 

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1 945. A life table for the black widow. Trans. Connecticut Acad. Sci. 36: 1 1 5- 1 3 1 . 
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1956. Contributions a Tetude du genre Nephila. Sur la variabilite des males de Nephila inaurata (Walck.). 
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80 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

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1949. Habits and control of the black widow spider. J. Econ. Entomol. 42:700-701. 
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Latrodectismo." Capi'tulo II (sistematica). Mus. Argentine Ciencias Nat. 23 p. 
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Argentina 27:51-59. 
Gonzales, L. 

1954. Latrodectus mactans mexicanus subsp. nov. Ann. Inst. Biol. Mexico 24:455-457. 
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1935. Report on the black widow spider. Louisiana Cons. Rev. 4(7):13-21. 
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1968. Molting behavior of the black widow spider Latrodectus mactans. Ann. Entomol. Soc. America 
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1935. The black widow spider. Univ. California Agr. Exp. Sta. Bull. no. 591, 30 pp. 
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1936. The black widow is rare in Michigan. Michigan Agr. Exp. Sta. Quart. Bull. 18:247. 
Irving, W. G. and E. H. Hinman 

1935. The blue mud-dauber as a predator of the black widow spider. Science 82:395-396. 
Jellison, W. L.andC. B. Philip 

1935. The biology of the black widow spider, Latrodectus mactans. Science 81:71-72. 
Juberthie, C. 

1 954. Sur les cycles biologiques des Araignees. Bull. Soc. Hist. Nat. Toulouse 89:299-3 1 8. 
Judd, W. W. 

1965. The black widow spider (Latrodectus variolus Walck.) in southwestern Ontario. Ontario Field Nat. 
19:24-25. 
Kaston, B. J. 

1937a. The distribution of black widow spiders. Science 85:74. 

1937b. The black widow spider in New England. Bull. New England Mus. Nat. Hist. No. 85, 1 1 p. 

1938. Check list of the spiders of Connecticut. Connecticut Geol. Nat. Hist. Surv. Bull. 60:175-201. 

1948. The spiders of Connecticut. Ibid. 70:92-93. 

1953. How to Know the Spiders. Dubuque, W. C. Brown Co., p. 156. 

1954. Is the black widow spider invading New England? Science 1 19:192-193. 

1968. Remarks on black widow spiders, with an account of some anomalies. Entomol. News 79:1 13-124. 
Kaston, B. J. and G. E. Jenks 

1937. Dipterous parasites of spider egg sacs. Bull. Brooklyn Entomol. Soc. 32:160-165. 
Keegan, H. L. 

1955. Spiders of the genus Latrodectus. American Midland Nat. 54:142-152. 
Knowlton, G. F. 

1935. The black widow spider. Utah Agr. Exp. Sta. Leaflet No. 57, 4 p. 
Lamoral, B. H. 

1968. On the nest and web structure of Latrodectus in South Africa, and some observations on body 
coloration of Z.. geometricus. Ann. Natal Mus. 20:1-14. 
Lawson, P. B. 

1933. Notes on the life history of the hourglass spider. Ann. Entomol. Soc. America 26:568-574. 
Levi, H. W. 

1958. Number of species of black widow spiders. Science 127:1055. 



1970 KASTON: AMERICAN BLACK WIDOW SPIDERS 81 

1959. The spider genus Latrodectus. Trans. American Micr. Soc, 78:7-43. 
1966. The three species oi Latrodectus found in Israel. J. Zool. (London) 150:427-432. 
1969. Notes on American theridiid spiders. Psyche 76:68-73. 
Lucas, S. and W. Biicherl 

1965. Importancia dos orgaos sexuais na sistematica de Aranhas. Mem. Inst. Butantan 32:89-94. 
Marikovskii, P. I. 

1949. Contribution to the ecology of the juvenile stages of the venomous spider. Latrodectus tredecimgut- 
tatus R., 1790. Zool. Zhur. 26:531-538 (in Russian). 
McCrone, J. D. 

1968. Biochemical differentiation of the sibling black widow spiders, Latrodectus maclans and L. variolus. 
Psyche 74:212-217. 
McCrone, J. D. and H. W. Levi 

1964. North American widow spiders of the Latrodectus curacaviensis group. Ibid. 71:12-27. 

1966. Postembryological development of spiderlings from two Peruvian Latrodectus populations. Ibid. 
73:180-186. 

McKeown, K. C. 

1943. Vertebrates captured by Australian spiders. Proc. Roy. Zool. Soc. New South Wales p. 17-29. 
Melchers, M. 

1963. Zur Biologic und sum Verhalten von Cupiennius salei (Keyserling), einer amerikanischen Ctenide. 
Zool. Jahrb., Abt. Syst. 91:1 -90. 

1964. Zur Biologic der Vogelspinnen. Z. Morph. Oekol. Tiere 53:517-536. 
Miller, I. M. 

1947. Amateur research on the black widow spider. Pest Control and Sanitation 2( 1 1 ):22-33. 
Millot.J. 

1949. Araneae. In, Traite de Zoologie, ed. by P. Grasse. Paris, Masson et. Cie. 6:589-743. 
Minton, S. A. 

1950. Injuries by venomous animals in Indiana. Proc. Indiana Acad. Sci. 60:315-323. 
Miyashita, K. 

1968. Growth and development oi Lycosa T-insignata Boes. et Str. under different feeding conditions. App. 
Entomol. Zool. (Japan) 3:81-88. 
Moles, M. L. 

1916. The growth and color patterns of spiders. J. Entomol. Zool. Pomona College 8(4): 129- 157. 
Montgomery, T. H. 

1908. Sex ratio and cocooning habits of an aranead, and the genesis of the sex ratio. J. Exp. Zool. 5:429- 
452. 
Muller, L. 

1952. La variabilite morphologique de Coeloles atropos Walck. Bull. Soc. Nat. Luxembourg, N. S., 45:26- 
35. 
Muma, M. H. 

1944. The black widow spider in Maryland. Univ. Maryland Ext. Bull. No. 103, 6 p. 
O'Rourke, F.J. 

1956. The toxicity of black widow spider venom. In, Venoms, A.A.A.S. Publ. no. 44, (ed. by Buckley, E. E. 
andN.Porges)p. 89-90. 
Parrott, A. W. 

1946. The eyes as taxonomic characters in spiders with special reference to Uliodon piscator (Hogg). Rec. 
Canterbury Mus. 5(2):95-103. 
Petrunkevitch, A. 

1911. A synonymic index-catalog of spiders of North, Central, and South America . . . etc. Bull American 
Museum Nat. Hist. 29:181. 
Pickard-Cambridge, F. O. 

1902. On the spiders of the genus La/ro^ecr«j Walckenaer. Proc. Zool. Soc. London 1:247-261. 
Pierce, W. D. 

1942. Utilization of the black widow parasite, and further data on spiders and parasites. Bull. Southern 
California Acad. Sci. 41:14-28. 
Pinter, L. J. 

1968. Species of widow spiders in Northern Argentina. Psyche 74:290-298. 
Rau, P. 

1924. Some life history notes on the black widow spider (Latrodectus mactans). Ibid. 31: 162-166. 
1935. The wasp, Chalvbion cvaneum Fabr., preys upon the black widow spider, Latrodectus mactans. 
Entomol. News 46:259-260. 



82 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Reese, A. M. 

1940. Variations in the markings of the black widow spider. J. Hered. 33: 1 18. 
Roberts, N. L. 

1941. Some notes on Australian Spiders. Proc. Roy. Zool. Soc. New South Wales p. 36-41. 
Robinson, M. 

1947. A new food supply for Latrodectus maclans. Entomol. News 58:258. 
Roewer, C. F. 

1942. (Latrodectus). Katalogder Araneae. Bremen 1:424-429. 
Semans, F. M. 

1941. Black widow spider distribution in Ohio. Ohio J. Sci. 41:380. 
Shuiov, .\. 

1 940. On the biology of two Latrodectus spiders in Palestine. Proc. Linn. Soc. London 1 52:309-328. 
1967. Biology and ecology of venomous animals in Israel. Mem. Inst. Butantan. 33:93-99. 
Shuiov, A. and \. Weissman 

1959. Notes on the life habits and potency of the venom of the three Latrodectus spider species in Israel. 
Ecology 40:5 15-5 1 8. 
Smithers, R. H. N. 

1944. Contribution to our knowledge of the genus Latrodectus in South Africa. Ann. So. African Mus. 
36:263-312. 
Szlep, R. 

1965. Web-spinning process and web-structure of Latrodectus tredecimgultatus. L. pallidus. and L. 

revivensis. Proc. Zool. Soc. London 145:75-89. 
1967. The web structure o^ Latrodectus variolus Walck. and L. bishopi Kaston. Israel J. Zool. (for 1966) 
15:89-94. 
Thorn, E. 

1967. Preliminary distributional list of the spiders of British Columbia. British Columbia Prov. Mus. Ann. 
Rept. (for 1966) p. 23-39. 
Wiehle, H. 

1967. Steckengebliebene Emboli in den Vulven von Spinnen. Senckenb. Biol. 48: 197-202. 
Wilson, L. F. 

1967. The northern widow spider, Latrodectus variolus. in Michigan. Michigan Entomol. 1:147-153. 
Witt, P. N.andC. F. Reed 

1965. Spider-web building. Science 149:1190-1197. 



Zoology Department, San Diego State College. San Diego. California 921 15 




MUS. COMP. 2:OQL. 
LIBRARY 

WAR 121971 

HARVARD 
UNIVERSITY 



EASTERN PACIFIC CROWN-OF-THORNS 

STARFISH POPULATIONS 

IN THE LOWER GULF OF CALIFORNIA 



THOMAS DANA AND ARTHUR WOLFSON 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



VOL. 16, NO. 4 24 NOVEMBER 1970 



EASTERN PACIFIC CROWN -OF-THORNS 

STARFISH POPULATIONS 

IN THE LOWER GULF OF CALIFORNIA 



THOMAS DANA AND ARTHUR WOLFSON 



ABSTRACT. — Populations of Acanthaster ellisii (Gray) were investigated on three islands in 
the southern Gulf of California. Average density (0.0045/m' or 1/225 m") exceeded that given 
in several definitions of normal densities for A. planci populations in the Indo-Pacific. Small 
patches of Porites were the most frequent food item; other hermatypic scleractinians, gorgon- 
ians, and algae were also fed upon. Estimates of coral coverage and growth rates, and Acan- 
tluister feeding rates, indicate that /I rw/u/iai^rcr predation is a significant source of coral mortality 
but that corals are not being eliminated from the areas studied. Gonad analysis suggests an ex- 
tended spawning season rather than a short synchronous one. Size-frequency data do not neces- 
sarily lead to the conclusion that populations of Acanthaster are expanding. 

RESUMEN. — Se estudiaron las poblaciones de Acanthaster ellisii (Gray) en tres islas de la zona 
meridional del Golfo de California. La densidad de dichas poblaciones presentaba un promedio 
de 0.0045 por m^, o sea de 1 por 225 m\ que vienen a ser concentraciones mas elevadas que las 
consideradas normales para. A. planci en el Incio-Pacifico. Pequenas agrupaciones de Porites con- 
stituyen el alimento mas frecuente de estos equinodermos, aunque tambien se observe que se ali- 
mentan de otras escleroactinias hermatipicas. gorgonias y algas. Las determinaciones sobre la 
cobertura de corales y los valores de crecimiento, asi como los datos relacionados con la alimen- 
tacion de Acanthaster indican que la predacion de este equinodermo es uno de las causes princi- 
pales en la mortalidad del coral, aun cuando los corales no aparecian exterminados en las zonas 
estudiadas. El analisis de las gonadas sugiere que la epoca de puesta no es corta y sincronica, 
sino prolongada. Datos sobre la frecuencia de tallas no indican. al parecer, que las poblaciones de 
Acanthaster amplien su area de dominancia. 

INTRODUCTION 

The presence of conspicuous populations of the eastern Pacific Crown-of-Thorns 
starfish Acanthaster ellisii (Gray) on three islands just north of La Paz, Baja California, 
Mexico, was recently brought to our attention. In the central and western Pacific in areas 
of luxuriant reef development the closely related starfish Acanthaster planci (Linnaeus) is 
reportedly undergoing population explosions (Barnes 1966; Weber 1969; Chesher 1969, 
1970). Reputed consequences of these "infestations" range from economic disaster for 
small isles and atolls of Oceania, destruction of fisheries upon which the inhabitants of 
Oceania depend for almost all their protein, severe land erosion by storm waves, to the 
extinction of madreporarian corals in the Pacific (Chesher 1969). More recently the 
assertions that Acanthaster aggregations represent a massive environmental upheaval, 
which seems to have no recorded precedent, have been challenged (Newman 1970; Weber 
and Woodhead 1970; Dana 1970). However, since no complex coral reef structures 
comparable to those of the Indo-Pacific are to be found in the Gulf of California, the 
presence of populations of A. ellisii apparently exceeding densities given as normal by 
Chesher (1969) for A. planci posed intriguing questions as to the ecological relationships 
between eastern Pacific corals, A. ellisii. and reef formation. Goreau (1964) has even 
suggested that under certain conditions Acanthaster might be an important factor limiting 
the growth and development of coral reefs. This prompted a short but intensive survey of 

SAN DIEGO SOC. NAT. HIST.. TRANS. 16(4): 83-90, 24 NOVEMBER 1970 



84 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



111° 



10° 










ISLA 
SAN JOSE 



S(o(.on -Cjfl SAN FRANCISCO 
1-5 '♦ 



O 







25° 



24° 



Figure 1 . Map of study area in lower Gulf of California, Mexico showing station locations. 

Isla San Francisco (24°55'N, 110°35'W) on 23 and 25 April, Isla San Jose (24°55'N, 
1 10°35'W) on 24 April, and Isla del Espiritu Santo (24°35'N, 1 10°25'W) on 26, 27, and 28 
April, 1 970, to investigate various aspects of the ecology of those populations (Figure 1 ). 

METHODS 

Area, depth, and per cent coral coverage of all surveyed areas were estimated. Usually 



1970 DANA AND WOLFSON: Acanthaster 85 

in making surveys two divers were towed at slow speeds ( 1 to 2 knots), one on each side of a 
12' skiff. In early stages of the survey all A. ellisii located were investigated for active 
feeding; later only occasional individuals were checked. Frequently, when visibility and the 
width of suitable substrate prohibited a thorough survey by towing, free or SCUBA diving 
was employed to more completely cover the area. At several stations both day and night 
observations were made. Only diving was utilized for night surveys, during which special 
emphasis was placed on locating juvenile A. ellisii (none were found). Specimens were 
collected from selected areas and individuals were kept in a large opaque aquarium on 
board ship. A variety of living corals were presented to these specimens. All the 
Acanthaster collected were measured (disk diameter) and gonad samples taken. 

RESULTS 

Isla San Francisco. — The area adjoining nearly the entire western half of the island 
was surveyed. Detailed observations were, however, limited to the southwestern sector. 

Station 1 was the submerged portion of a spit composed of small boulders (<0.5m in 
diameter) at the southern end of a small sandy embayment. The area investigated 
measured some 120x10m, with depths ranging from 0.5 to 2m. All observations were 
made while snorkeling. Coral coverage was 2 to 3%, consisting of small patches of Porites 
(3-6 cm in diameter) and scattered individual heads of Pocillopora. Seven A. ellisii, all in 
the open, were located; most were feeding on small Porites patches during the day. There 
was evidence of occasional feeding on Pocillopora, but none of these coral heads were 
completely eaten. (Density of A. ellisii: 0.006/m- or l/171m-.) 

Station 2 was located along a rocky shoreline across the sandy embayment from 
Station 1 and included the point at the northwestern end of the bay. The substrate 
consisted of large boulders (>lm in diameter) that had tumbled down onto a flat sandy 
bottom. These boulders were almost completely covered with algae. The area surveyed 
stretched for about 315m along the shore and varied in width from 8m on the inner end to 
15m at the northwest point. Depth of the water to sand bottom gradually increased from 5 
to 15m at the point. Day observations were made towing, free diving, and with SCUBA. 
Coral coverage was estimated to be less than 1 %, except at the point where it was between 
2 and 3%. Small encrusting patches of Porites and small heads of Pocillopora were 
present. Several larger heads of Pocillopora and patches of Porites (>30 cm in diameter) 
were found in shallow water at the point. A total of 27 A. ellisii (including 7 taken by 
Faulkner on 18 April) were scattered throughout the area. Nearly all were in water 
between 1 and 5m deep and were feeding on patches of Porites. A single individual which 
was not feeding was found in 12m of water at the northwest point. (Density of A. ellisii: 
0.009/m-or 1/1 17m'.) 

Station 3 began on the north side of the point where Station 2 terminated and 
continued for some 200m into an adjacent cove. The substrate was similar to that of 
Station 2 except the boulders were smaller and less algal covered. The rocky area was 5 to 
8m wide, ending on a smooth sand bottom in 3 to 4m of water. Coral coverage was 
estimated to be less than 1%. Four Acanthaster were seen but were not checked for 
feeding. (Density of^. e//m/; 0.003/ m' or l/400m-.) 

Station 4 was located on the north side of a small cove opposite Station 3. The 
substrate along the inner 75m of the cove was a grey, vesicular basalt dipping seaward 
gently for about 18m to a depth of 3 to 4m, and then more sharply to a smooth sand 
bottom at a depth of 9m. This area was surveyed by towing and free diving during the day. 
The bottom over the remaining 3 10m length of the area consisted of large boulders and was 
surveyed by day towing and a SCUBA dive at night. The entire station was densely covered 



86 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

with algae. Coral cover was between 1 and 2% and consisted of small patches of Porites 
and occasional small heads of Pocillopora. A total of 24 Acanthaster (including 12 
collected by Faulkner on 19 April) were found at this station. Most individuals observed 
during the day were feeding in the open on small patches of Porites. Identical behavior was 
observed during the night dive with the additional observations of one completely cleaned 
colony o'( Pocillopora and a single Acanthaster feeding on a gorgonian {Pacifigorgia sp.) 
in a crevice. (Density of A. ellisii: 0.006/ m- or l/160m-.) 

Station 5, located along the southern side of the cove adjacent to Station 4, comprised 
an area of 300 x 10m. The bottom was an algal-covered sloping rock outcrop with a few 
boulders scattered at its seaward extremity. Sand replaced the rocky substrate in about 3m 
of water. Observations were made by towing and free diving in daylight. Coral coverage 
was 8 to 10%, consisting principally of encrusting to submassive patches of Porites, a few 
heads of Pocillopora, and an occasional patch of Pavona. (Density of ^. ellisii: 0.002/m- 
or l/600m-.) 

Isla San Jose. — A single station (Station 6) was made at this island — around a 
linear rock outcrop well out into the mouth of the large bay on the southwestern extremity 
of the island. The substrate consisted of large algal covered boulders, and water depth to 
sand bottom ranged from 6m at the northern end of the outcrop to 14m at the southern 
end. The area surveyed was about 375m long and 10 to 12m wide. Corals present were 
Porites, Pocillopora. and Tubastrea. and cover for most of the area was about 1%, 
increasing slightly at the southern tip where a strong current prevailed. Observations were 
made towing and with SCUBA. During the day 5 Acanthaster were found scattered along 
the western side of the outcrop, all in less than 4m of water. Three were in the open, fully 
exposed but not feeding, another was feeding on a gorgonian {Pacifigorgia sp.), and one 
had its stomach everted over a clump of Padina sp. (a lightly calcareous brown alga). All of 
these specimens were collected and no additional individuals were located that night. 
(Density of/4, ellisii: 0.00\ /m~ or l/750m-.) 

Isla del Espiritu Santo. — Two stations were occupied in the northwestern sector of 
the mouth of an embayment on the western side of the isthmus. The first. Station 7, was 
around a small rock outcrop a short distance out into the bay. The surveyed area was 
approximately 500m-. All observations were made snorkeling during the day. Algal cover 
was much sparser than at previous stations and coral coverage was between 4 and 5%. 
Small patches of Porites were present, a single clump of Psammocora (Stephanaria) was 
noted, and a number of colonies of Pocillopora (up to 0.75m in diameter) were scattered 
about. Eight Acanthaster were observed in 1 to 3m of water. (Faulkner also collected one 
individual from this locality on 15 April.) Of the 8, 7 were feeding on tiny patches of 
Porites, and one was under a large head of Pocillopora — a small portion of which had 
been eaten. (Density of A. ellisii: 0.0\6/m~ or l/63m-.) 

A small point opposite Station 7 was selected for Station 8. An estimated 1 100m of 
rock outcrops and boulders were investigated by free diving. Algal and coral coverage, as 
well as the kinds of corals, were similar to Station 7. Of the 8 Acanthaster seen during the 
day, 6 were feeding on Porites and one on Psammocora (Stephanaria). (Density of A. 
ellisii: 0.001 /m-OT l/138m'.) 

Two stations were made at the northwestern extremity of Bahia de San Gabriel, 
located in the southwestern sector of Isla del Espiritu Santo. The first. Station 9, was 
located just outside and to the north of the bay at Punta Prieta and covered approximately 
600m- of rock ledges and boulders in water less than 5m deep. Coral coverage was between 
3 and 4%, principally Pocillopora, and under ledges, Tubastrea. No Acanthaster were 
found during the day or night. 



1970 DANA AND WOLFSON: Acanlhaster 87 

Station 10 was located just inside the bay where a fringing reef is forming in shallow 
water. Coral growth terminated on a sand bottom in less than 2.5m of water. Squires 
(1959) described a series of coral patches aligned as a barrier across the central portion of 
this same bay; however, that area was not investigated. Four species of Pocillopora were 
the principal reef builders with occasional scatterings of Pavona, Psammocora (Step- 
hanaria), and Pontes. At one end of the reef structure there was an extensive patch of 
Pontes in very shallow water. Approximately 1500m'^ were thoroughly searched by 
snorkeling during the day. A single specimen o{ A. ellisii, the largest located during the 
survey, was found under a large head of Pocillopora that had a freshly killed portion 
comparable in size to the disk area of the starfish. No other Acanthaster were found at this 
station. However, occasional small white patches were noted on branch tips o{ Pocillopora 
clumps. Closer examination revealed that the regular five-armed sea star Pharia pyrami- 
data (Gray) was everting its stomach in a manner similar to Acanthaster and removing 
coral tissue. Steinbeck and Ricketts (1941) reported Pharia to be common in coral areas in 
the Gulf of California, but our observation is the first to indicate that they feed on coral. 

Thirty specimens o{ A. ellisii were collected. Disk diameters ranged from 62mm to 
142mm with a mean of 97.9mm (Figure 2). No juveniles were found. All of these individuals 
fit within the size range of specimens available to Case (1962), although our mean is slightly 
greater. 

Gonad samples taken from 14 males and 12 females were analyzed by Dr. John S. 
Pearse of the Kerckhoflf Marine Laboratory. Eighteen individuals were ripe, including the 
largest and smallest collected — both females. Numerous mature spermatozoa and a thick 
layer of spermatogenic cells in the 1 1 ripe males, and the presence of various-sized, 
growing oocytes alongside abundant, fully developed ones in the 7 ripe females, suggests 
that gametes are produced over a considerable period of time, or that the samples were 
taken during the peak of reproductivity. Four females contained several sizes of maturing 
oocytes but few full-grown ones. One female had recently spawned and appeared to be 
beginning a new cycle of gametogenesis. Three males were not ripe but were either 
maturing or perhaps had recently spawned and were beginning a new cycle of gametogen- 
esis. 

DISCUSSION 

The behavior o{ A. ellisii differed from that described for A. planci by Goreau (1964) 
and Chesher (1969). Rather than hiding by day and feeding at night, A. ellisii was almost 
always conspicuously out in the open, and usually feeding, during the day. All A. ellisii but 
one were seen in water shallower than 4m. Their limited distribution was undoubtedly 
related to the narrow distributional limits of suitable food organisms. There was no 
apparent clumping oi Acanthaster on a scale of a few tens of square meters. 

Hermatypic scleractinian corals appeared to be the preferred food item for A. ellisii — 
particularly small encrusting patches of Porites estimated to be no more than 2 years old. 
Feeding experiments tended to support this observation. Goreau (1964) noted that in the 
southern Red Sea A. planci selected smaller coral heads more frequently than larger ones. 
There was no field evidence that Acanthaster feeds on the ahermatypic coral Tubas trea, 
and this coral was avoided in feeding experiments. However gorgonians of the genus 
Pacifigorgia were fed on occasionally, and one Acanthaster was seen in normal feeding 
attitude on a clump of the alga Padina. 

All areas surveyed except the northwestern portion of Isla San Francisco were in the 
lee of the prevailing northwesterlies (November to May) and southeasterlies (June to 
October) (Roden, 1964). Such normally sheltered locations have been reported to support 



88 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

larger average Acanthaster population levels (Chesher, 1970; Weber, 1970). 

Ninety Acanthaster (including the 20 taken by Faulkner) were located within the 
20,250m- surveyed in detail. The average density obtained, 0.0045/m- or about l/225m-, 
exceeds several of Chesher's definitions of normal population densities for A. planci: 2 or 
3/ 1000m-, 4 or 5/km of reef, 1/hour of search, and 20/20 minutes of search but usually no 
more than 8 (Chesher, 1969, 1970). For several stations densities approached, and at one 
station exceeded, the density reported for the infestation of Double Reef, Guam (886 
animals on 90,000m- of reef, Chesher, 1969). The effect of the starfish on coral formations 
in the lower Gulf of California is certainly problematical, especially considering the 
general lack of reef development and sparse distribution of corals in that area (Squires, 
1959). Excluding the 2 stations from Bahia de San Gabriel, coral coverage, in terms of 
projected images of individual colonies, averaged about 3% over 18,150m-. There are then 
approximately 6.1m- of coral standing crop available for each Acanthaster, although the 
actual feeding surface is certainly greater. Using a consumption rate of twice the area of 
the disk per day (Chesher, 1969, for A. planci), approximately 5.3m- of coral would be 
consumed by an average size A. ellisii in a year's time. Such a feeding rate would require a 
replacement rate of coral standing crop — in terms of areal coverage — of 87% annually. 
However, this feeding rate, considering the effects of temperature differences on metabolic 
rate (Kinne, 1963), is probably an overestimate (surface temperatures in the lower Gulf of 
California range from 17 to 31°C with an annual mean of 24.7°C, while the tropical 
western Pacific remains nearly uniform at 28°C; see Roden, 1964). 

The relationship between increase in weight and increase in area of the projected 
image of a coral colony is difficult to estimate and depends in a complex manner on such 
factors as growth form, degree and mode of branching, and skeletal density. Nevertheless, 
growth data giving annual increments of increase as per cent gain in weight does not seem 
an unreasonable means of approximating a coral replacement rate. In Hawaii, Edmondson 
( 1 929) found an average annual weight increase for a number of colonies of various sizes of 
two species of Porites to be 60.7% and 90.4% and of three species of Pocillopora to be 
148.0%, 137.5%, and 103.9%. Since the Hawaiian Islands are on the border of the tropics, 
coral growth data from there seem appropriate for comparison, even though Hawaiian 
growth rates certainly exceed those in the lower Gulf of California. Despite the com- 
plications, it appears that under present conditions coral growth alone should be sufficient 
to provide enough tissue to satisfy the energetic requirements of current population levels 
of A. ellisii. 

The gonad analysis indicates that in the Gulf of California Acanthaster has at least a 
protracted, if not continuous, spawning season. This does not agree with the report from 
Green Island (about 16°S) on the Great Barrier Reef of a highly synchronous breeding 
season in December and January for A. planci (Endean, 1969), nor with the contention of 
Chesher ( 1 969) of a breeding season for A . planci at Guam (about 1 6°N) during November 
and December. Our data, however, agree with analyses by Pearse on specimens from 
Guadalcanal, Guam, Ifaluk, and Wolei (Eldredge, 1970), and with Mortensen's observa- 
tion (1931) from off Java (about 6°S) that, for A. planci, the sexual products are not shed 
all at once but in portions at different times. Furthermore, continual influx of young, or 
recruitment extending over many months, could account for the lack of modes represent- 
ing year classes in the size-frequency distribution of the populations of A. ellisii observed. 

Since no growth rate data are available for A. ellisii, age structure of the populations 
cannot be inferred from their size distribution. However, one important point about the 
shape of the size-frequency curve, as it relates to population increases, should be made: the 
peak at intermediate sizes (see Figure 2) does not necessarily indicate an unusually large 



1970 



DANA AND WOLFSON: Acanthaster 



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9 


- 






8 


- 






7 


- 






6 


















5 
4 
3 


- 


















2 


















1 













' 61-7o' 71-eo' 81-9o' 91-IOOM01-Ito')n-I2ol|21-130M31-I4o'l4t-I5o' 
SIZE (mm) 



Figure 2. 
mm). 



Size frequency histogram based on 30 specimens. Range, 62-142 mm; mean, 97.9 mm (median, 95.5 



recent influx of young. Several combinations of survivorship curves coupled with non- 
linear growth could give size-frequency distribution curves of the shape observed even 
when annual recruitment is relatively constant over a period of several years. Probably the 
populations observed contain individuals in several year classes, and any contention for a 
recent population increase would be highly speculative. 

Lacking adequate knowledge of recruitment, settling requirements, survivorship, 
spawning periods and behavior, growth rates, rates of mortality from various sources, and 
longevity of both corals and Acanthaster, as well as information concerning past popu- 
lation levels and fluctuations, we consider drawing any conclusions as to the consequences 
of present levels of predation on corals in the lower Gulf of California by A. ellisii tenuous 
at best. However, the feeding pressure exerted by A. ellisii, when coupled with suboptimal 
temperatures for corals resulting in relatively slow growth rates, an observed abundance of 
boring organisms, and paucity of coralline algae to serve as a binding agent, may 
contribute significantly to the almost total absence of reef formation in the Gulf of 
California. 

ACKNOWLEDGMENTS 

We would like to thank Dr. D. John Faulkner for bringing the situation in the Gulf to our attention. Garth 
Nicholson for help with the field work. Dr. John S. Pearse for analysis of the gonad samples. Dr. William A. 
Newman for encouragement and critical reading of the manuscript, and the Foundation for Ocean Research for 
travel and ship time. 



LITERATURE CITED 

Barnes, J. H. 

1966. The crown of thorns starfish as a destroyer of coral. Australian Mus. Mag. 15: 257-261. 
Bayer, F. M. 

1951. A revision of the nomenclature of the Gorgoniidae (Coelenterata: Octocorallia), with an illustrated 
key to the genera. Wash. Acad. Sci. 41: 91-102. 



90 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Caso, M. E. 

1962. Estudios sobre Asteridos de Mexico: Observaciones sobre especies Paciticos del genero Acanthaster y 
descripcion de una subespecie nueva, Acanthaster ellisii pseudoplanci. Ann. Inst. Biol. Univ. Mexico 
32:313-331. 

Chesher, R. H. 

1969. Destruction of Pacific corals by the sea star /lca«r/ia.y/er/7/a«c/'. Science. 165:280-283. 

1970. Acanthaster planci: Impact on Pacific coral reefs. U.S. Dept. Interior. Publ. 187631. 
Dana, T. F. 

1970. Acanthaster: a rarity in the past? Sciences. 169:894. 
Edmondson, C. H. 

1929. Growth of Hawaiian corals. Bernice P. Bishop Mus., Bull. 58: 1-38. 
Eldredge. L. G. 

1970. Acanthaster Newsletter, no. 2, from the Marine Laboratory, Univ. of Guam, Agana, Guam. 
Endean, R. 

1969. Report on investigations made into aspects of the current Acanthaster planci (Crown-of-thorns) 
infestations of certain reefs of the Great Barrier Reef. Brisbane, Queensland Dept. of Primary 
Industries, Fisheries Branch. 

Goreau, T. F. 

1964. On the predation of coral by the spiny starfish Acanthaster planci (L.) in the southern Red Sea. Israel 
South Red Sea Expedition, 1962. Rept. no. 2, Bull. Sea Fish. Res. Sta., Haifa 35: 23-26. 
Kinne, O. 

1963. The effects of temperature and salinity on marine and brackish water animals. Oceanogr. Mar. Biol. 
Ann. Rev. 1:301-340. 

Mortensen. Th. 

1931. Contributions to the study of the development and larval forms of echinoderms: I-II. D. Kgl. Danslce 
Vidensk. Selsk. Skrifter, naturvidensk. og mathem. Afd., 9 Raekke, IV 1 : 1-39. 
Newman, W. A. 

1970. /lca«?/ia.?rfr.- a disaster? Science 167: 1274-1275. 
Roden, G. I. 

1964. Oceanographic aspects of the Gulf of California. In Marine Geology of the Gulf of California, A 
Symposium. Memoir 3. Amer. Assoc. Petrol. Geol. Edited by T. H. van Andel and G. G. Shor, Jr. 

Squires, D. F. 

1959. Results of the Puritan-American Museum of Natural History Expedition to Western Mexico: Corals 
and coral reefs in the Gulf of California. Bull. Amer. Mus. Nat. Hist. 118: 371-431. 
Steinbeck, J., and E. F. Ricketts 

1941. The Sea of Cortez, a Leisurely Journal of Travel and Research, with a Scientific Appendix 
Comprising Materials for a Source Book on the Marine Animals of the Panamic Faunal Province. 
New York, Viking Press. 
Weber, J.N. 

1969. Disaster at Green Island — other Pacific islands may share its fate. Earth and Mineral Sci. 38: 37-41. 
Weber, J. N., and P. M. J. Woodhead 

1970. Ecological studies of the coral predator Acanthaster planci in the South Pacific. Marine Biology 6: 12- 
17. 



Scripps Institution of Oceanography, University of California-San Diego, La Jolla, 
California 92037 




^ MUS. COMR ZOOL. 

^ LIBRARY , 



MAR 121971 

HARV" 
UNlVEKoi 1 ii 



EVOLUTION OF PEROMYSCUS ON NORTHERN ISLANDS 
IN THE GULF OF CALIFORNIA, MEXICO 



TIMOTHY E. LAWLOR 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



VOL. 16, NO. 5 24 FEBRUARY 1971 



EVOLUTION OF PEROMYSCUS ON NORTHERN ISLANDS 
IN THE GULF OF CALIFORNIA, MEXICO. 

TIMOTHY E. LAWLOR 



ABSTRACT. — Mice of the genus Peromyscus on northern islands of the Gulf of California and 
adjacent mainland areas were examined to trace the divergence of populations there. A total of 
27 qualitative characters of the osteology, pelage, phallic morphology, soft anatomy, serology, 
and karyology was examined in detail. Morphometric characters and dental patterns also were 
studied, and matings of pertinent forms were attempted with limited success. 

The island and mainland forms were treated numerically according to the above qualitative 
characters, as follows: ( 1) Two Prim Networks were computed, utilizing different combinations of 
characters. Each indicated that P. stephani (Isla San Esteban) is closely related to P. boylei, and 
that those two species and P. crinitiis are only distantly related to the remainder of the island 
and mainland forms. (2) A dendogram (Wagner Diagram) was computed for the latter, using 
the quantitative phyletic method. P. eretuicus was considered ancestral on morphologic and 
zoogeographic grounds. P. giiardia (Islas Angel de la Guarda, Granito, and Mejia) is the most 
divergent of the eremicus-Wkc forms and cladistically is closest to P. merriami. P. interparietalis 
(Islas San Lorenzo Sur, San Lorenzo Norte, and Salsipuedes) also is relatively far removed from 
the hypothetical eremicus-\'\V.Q ancestor. Populations from the Baja Californian and Sonoran main- 
lands and Isla Tiburon (P. eremicus), and Isla Turner {P. collotus), are closely related and 
should be considered conspecific. On zoogeographic grounds, the populations on western Gulf 
islands (giiardia, interparietalis) probably are derived from a Baja Californian eremiciis-hke 
progenitor, whereas eastern island forms (collatiis, eremicus tihiironensis) and stephani prob- 
ably are derived from Sonoran eremicns-hke and boylei-Uke forms, respectively. Evidence from 
morphology, amount of gene flow between islands and between islands and the mainland, and 
time of formation of the islands, suggests that the time interval since initial formation of the 
islands has been the principal factor affecting divergence of the island populations. 

Trends in the evolution of certain characters among Gulf Peromyscus suggest that complex 
features may result from simple conditions in the phallus and dentition, and that acrocentric chro- 
mosomes derive from a bi-armed condition. The data suggest that the subgenus Haplomylomys, 
which consists of eremicus-Uke species, contains primitive members of the genus. 

RESUMEN. — Se estudiaron los ratones del genero Peromyscus en las islas septentrionales del 
Golfo de California y zonas adjacentes del continente, con objeto de determinar las divergencias 
que presentan sus poblaciones. Se examinaron con todo detalle un total de 27 caracteres morfo- 
logicos, relacionados con la osteologia, pelaje, organos sexuales externos y otros caracteres ana- 
tomicos, serolologicos y citologicos. Tambien se analizaron los caracteres morfometricos y la 
denticion, intentandose ademas cruces entre las formas pertinentes, obteniendo exitos muy limitados. 
Las formas encontradas en las islas del Golfo de California y en el continente se analizaron 
numericamente en cuanto a los caracteres morfologicos arriba mencionados, en la forma siguiente: 
1 ) Se efectuaron dos "Prim Networks," utilizando diferentes combinaciones de caracteres. En 
cada caso resulto que P. stepliani (isla de San Esteban) aparecia como pariente proximo de 
P. boylei, y estas dos especies con P. crinitiis resultan parientes lejanos de las formas restantes 
que habitan estas islas y el continente. 2) El diagrama denditico (diagrama de Wagner) se com- 
pute para P. crinitiis, utilizando el metodo filogenetico cuantitativo. P. eremicus aparece asi 
como una especie ancestral, basandonos en la morfologia y la zoogeografia. P. guardia (islas 
Angel de la Guarda, Granito y Mejia) es la especie que diverge mas de las formas del tipo 
eremicus, y la mas proxima en la escala a P. merriami. Peromyscus interparietalis (Islas de San 
Lorenzo Sur, San Lorenzo Norte y Salsipuedes) aparece como una segregacion lejana del ascen- 
diente hipotetico tipo eremicus. Las poblaciones de P. eremicus de las zonas continentales de 
Baja California, Sonora y de la isla Tiburon, y las de P. collatus de la isla Turner aparecen muy 



SAN DIEGO SOC. NAT. HIST, TRANS. 16(5): 91-1 24, 24 FEBRUARY 1971 



92 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

relacionadas entre si, por lo que podrian considerarse co-especificas. Bajo el punto de vista 
zoogeografico, las poblaciones de las islas occidentales del Golfo (guardia, interparietalis) derivan 
probablemente de un progenitor tipo eremiciis de Baja California; mientras que es posible que 
las formas de las islas orientales (collatus, eremicus, tihuronensis) y stephani procedan respec- 
tivamente del tipo eremicus y del tipo boylei. Las caracteristicas morfologicas evidencian un flujo 
importante de genes de unas islas a otras y entre estas y tierra firme durante el perido de forma- 
cion de dichas islas; lo cual sugiere que el lapso de tiempo transcurrido desde que se inicio la 
formacion de esas islas constituye el factor principal responsable de la divergencia encontrada en 
las poblaciones insulares. 

La tendencia o curso en la evolucion de ciertos caracteres en los Peromyscus del Golfo sugiere 
que estructuras complejas pueden resultar simplemente de las condiciones de los organos sexuales 
externos y la denticion, y que los cromosomas acrocentricos derivan de una condicion bifurcada. 
Los datos obtenidos indican que el subgenero Haplomylomys, que incluye las especies tipo 
eremicus, contiene los miembros primitives del genero. 

The ecologic and geographic characteristics of islands make them particularly suited 
for studies concerning differentiation and adaptation in natural populations. In general, 
climatic stability, decreased ecologic diversity, and increased isolation distinguish 
islands from mainland areas. In the sense of Preston (1962), the plant and animal 
populations of an island form a complete ("canonicaT') system as a result of these 
peculiarities, while mainland populations represent only a "sample" of a more widely 
distributed and more diverse biota. Thus, effects of isolation are more pronounced on 
islands than on continental areas. 

In addition, islands presumably are subject to colonization by organisms undergoing 
primary radiation on continental areas. This seems like a reasonable assumption, although 
the reverse situation undoubtedly occurs to a lesser degree. Consequently, insular popu- 
lations may constitute unique control groups in which to examine patterns of evolution and 
divergence of particular groups of organisms. 

Mice of the genus Peromyscus are widely distributed in North America in insular and 
mainland situations. They are nearly ubiquitous on island and mainland areas in and 
surrounding the Gulf of California. No less than 18 species of two subgenera are 
recognized there, of which ten are island endemics. It appears that at least five of the seven 
non-endemic species were important for radiation of the group onto the islands of the Gulf. 
The following account is an assessment of the morphologic, serologic, and karyologic 
divergence of the island populations o{ Peromyscus relative to one another and to those on 
the mainland of Baja California to the west and Sonora, Mexico, to the east. 

The geographic area of study consists of the northern group of Gulf islands (Figs. 1 
and 2). These islands form an irregular chain from one side of the Gulf to the other, thus 
affording several possible access routes to and from the mainland. In addition, the cham is 
separable into deep- and shallow-water islands. The latter group consists of islands 
(Turner, Tiburon) occupying waters within the 1 10 meter depth contour, the level to which 
the sea is thought lo have been lowered by eustatic changes during the Pleistocene, whereas 
the former group (San Esteban, Salsipuedes, the Lorenzos, and Angel de la Guarda and 
nearby islands) consists of islands that attained their present configuration as long ago as 
Pliocene (Anderson, 1950). Thus, certain of the islands are chronologically much younger 
than others by virtue of their relatively recent separation from the mainland. 

One would expect a greater degree of morphological and genetic differentiation in 
peromyscines inhabiting distant and deep-water islands as a result of more effective 
isolation than in those mice on islands in close proximity to the mainland and in shallow 
water. The latter islands could be subjected to repeated invasions by mice from mainland 
populations, resulting in suppression of morphological or genetic differences that might 



1971 



LAWLOR: Peromyscus 



93 




Figure 1 . Map of the northern part of the Gulf of California, Mexico, and surrounding areas. The area enclosed 
in dotted lines is enlarged and presented in detail in Fig. 2. Numbers identify localities discussed in text and 
specified in "Specimens Examined," and are as follows: 1 — Turtle Bay: 2 Barril: 3 — Bahfa de los Angeles; 4 
— San Francisquito; 5 — El Marmol; 6 — San Telmo: 7 — Escondido: 8 — Punta Penasco; 9 — Tucson; 10 — 
Imuris; i 1 — Puerto Libertad; 12 — Punta Sargento; 13 — Bahia Kfno; 14 — Isla San Pedro Nolasco; 15 — 
Presa Obregon. 

Otherwise have arisen. However, two other alternatives seem plausible: ( 1) the environment 
on the proximal, shallow-water islands may more closely resemble that on the mainland, 
and (2) the time interval since the initial formation of the shallow-water islands may not 
have been sufficiently long for a large amount of differentiation to have taken place. The 
amount and trends of variation in the mice from the different islands and the two mainland 
areas provide sufficient data for determining which of the above factors is relevant. 

The affinities of the species of Peromyscus on the northern islands have not been 



94 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Sonora 



. GRANITO 




I. ANGEL DE LA GUARDA 



PUNTA SARGENTO 



BAHIA DE LOS 
ANGELES 



a 



I. PARTIDA 
\. RAZA 




\. TIBURON 



BAHIA KINO 



SALSIf^UEDES* j— . 

I. SAN LORENZO NORTe'V^ J-^ 

I. SAN LORENZO SUR 



Baja California 




0|. TURNER 
I. SAN ESTEBAN 




Figure 2. Map of the northern islands of the Gulf of California, Mexico, and adjacent mainland areas enlarged 
from the insert in Fig. 1 . 

thoroughly documented. Currently populations of five species are recognized, all of which 
are included in the subgenus Haplomylomys and are considered closely related to P. 
eremicus: 

P. eremicus tiburonensis (Mearns, 1897); Isla Tiburon 

P. collatus Burt, 1932; Isla Turner (= I. Datil) 

P. stephani Tovjnsend, 1912; Isla San Esteban 

P. guardia guardia Townsend, 1912; Isla Angel de la Guarda 

P. guardia mejiae Burt, 1932; Isla Mejia 

P. guardia harbisoni Banks, 1967; Isla Granito 

P. interparietalis interparietalis Burt, 1932; Isla San Lorenzo Sur 

P. interparietalis lorenzo Banks, 1967; Isla San Lorenzo Norte 

P. interparietalis ryckmani Banks, 1967; Isla Salsipuedes 
Taxonomically these forms have remained virtually unchanged since their description, 
except that tiburonensis is now considered a subspecies of eremicus (Osgood 1909; cf. 
Mearns, 1897), and interparietalis is considered specifically distinct from guardia (Banks, 
1967; cf. Burt, 1932). Hooper and Musser (1964b) have suggested, on the basis of phallic 
morphology, ihdi stephani m-dy be closely related to species of the subgenus Peromyscus. 



MATERIALS AND METHODS 

Specimens examined in this study were collected during trips to the Gulf of California 
and surrounding areas in the summers of 1967 and 1968, and in January, 1969, or were 
borrowed from the following institutions: California Academy of Sciences (CAS); Dickey 
Collection, University of California, Los Angeles (UCLA); San Diego Natural History 
Museum (SD); Department of Zoology, University of Arizona (UA); Museum of 



1971 LAW LOR: Peromyscus 95 

Vertebrate Zoology, University of California, Berkeley (UC); Museum of Natural 
History, University of Kansas (KU); Museum of Zoology, University of Michigan 
(UMMZ); and the United States National Museum (USNM). Both live and preserved 
examples of each of the island populations were obtained. 

Except for analysis of variation in dental patterns, only adult wild-caught mice were 
treated for purposes of studying morphologic, serologic, and karyologic features. All age 
groups were examined in the former, although specimens with excessive tooth wear were 
omitted. Adult status was determined according to the methods of Lawlor (1964) and 
HotTmeister (1951). Briefly, an animal was considered an adult if there was at least 
moderate wear on the lingual cusps of M' and M- (the M^^ generally is well worn at this 
age), and if the specimen was in advanced (''adult") pelage. Specimens examined for 
serologic and karyologic properties were considered adult after retention in the laboratory 
for at least two months. 

in osteological considerations I dealt with quantitative and qualitative measures of 
cranial and other skeletal features. Measurements, in millimeters, were taken with dial 
calipers. Post-cranial features were examined from whole skeletons except that the number 
of caudal vertebrae was determined from X-rays. The latter technique provides an accurate 
means of counting vertebrae and avoids potential error in vertebral counts of whole 
skeletons owing to vagaries of preparation. External characters include tield-taken body 
measurements and pelage features. 

Dental patterns were examined according to a modified scheme of the procedure 
specified by Hooper (1957). Lophs and styles were considered present only if they 
comprised a prominent element of an enamel valley. Even so, considerable variation 
accrues in the development and appearance of these structures. Variation is particularly 
evident in the shape and placement of styles, but no rigorous attempt was made to 
determine homologies. 

Phalli of freshly killed mice were extracted and fixed in 10% formalin. After everting 
the prepuce over the proximal portion of the glans, the following procedure was used for 
clearing and staining: 

2 % KOH solution ca. 60 minutes 

Alizaren red stain (in 2% KOH) 1-2 hours 

Distilled water wash 1 minute 

Solution of 2 pts. HOH, 1 pt. glycerin ca. 24 hours 

Solution of 1 pt. HOH, 2 pts. glycerin ca. 24 hours 

Glycerin permanent storage 

The procedure for dried specimens dilTered slightly. Good results were obtained by 
shortening the clearing and staining times by about one-half. This reduces the chances for 
sloughing of the epithelial layer, a common occurrence if the glans was kept in KOH 
solutions for long periods. The remaining steps were the same. 

Karyotypes were examined by means of a bone marrow technique (Patton, 1967). An 
average of 10 metaphase cells was counted to determine the diploid number of each 
individual. The fundamental number ("Nombre FundamentaP' of Matthey, 1951) was 
determined as the total number of autosomal arms (excluding the sex chromosomes). The 
system for describing the chromosomes (Patton, 1967) was as follows: 

Chromosome type Arm ratio 

Metacentric Less than 1: 1. 1 

Submetacentric 1:1.1 to 1:1.9 

Subtelocentric 1:2 or greater 

Acrocentric (telocentric) One arm only 



96 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Eleclrophoretic analyses were made according to the modified method of Smithies 
(1955) used by Brown and Welser (1968). 

The taxonomic designations that are applied below to island and mainland popu- 
lations concerning character diagnoses, and the discussion of phylogenetic and zoogeogra- 
phic relationships that follows, correspond to the currently held taxonomy of those forms 
(see above). They are used only to facilitate interpretation by the reader; they do not reflect 
any taxonomic evaluation made prior to construction of the phylogeny and taxonomic 
conclusions. 

Statistics and construction of the dendrogram and phenograms were calculated by use 
of an I BM 360/67 computer at the University of Michigan Computation Center. 

MORPHOLOGIC VARIATION 

MORPHOMETRIC CHARACTERS 

A total of 20 external and cranial dimensions was examined. Six of these (total length, 
length of tail, greatest length of skull, zygomatic breadth, length of rostrum, and length of 
maxillary toothrow) are presented in Figs. 3-5. The remainder are either relatively 
invariable or exhibit similar geographic changes as the ones treated in detail here. 

Mice of the guardia islands (Angel de la Guarda, MejTa, and Granito) show no 
consistent trends of inter-island variation in size, although significant differences (P<.05) 
are evident in certain dimensions. However, interparietalis (Isla Salsipuedes, San Lorenzo 
Norte, and San Lorenzo Sur) exhibits a trend of increasing size in nearly all dimensions 
from Salsipuedes in the north to San Lorenzo Sur in the south. An exception is zygomatic 
breadth, and the relative constancy of this dimension together with the variation for 
greatest length of skull gives interparietalis from Salsipuedes a shorter, broader-headed 
appearance than its southern island counterparts. P. stephani (Isla San Esteban) differs 
from other island forms in having cranial dimensions that usually average larger. 

In general, forms from Islas Turner (collatus) and Tiburon {eremicus) were similar to 
mainland eremicus on the basis of morphometric characters. Other mainland populations 
o{ eremicus in the Gulf area do not differ importantly from the two samples given in Figs. 
3-5 (for example, see Lawlor, in press). 

The large differences in certain dimensions evident between insular populations of the 
same species (e. g., in interparietalis and guardia) suggest that isolation of these mice on 
islands has resulted in the retention of morphometric differences that generally are 
eliminated by higher rates of gene flow in continental populations. For example, 
differences of significant proportions usually are not evident in morphometric data for 
mainland populations o^ eremicus {Ibid.). 

DENTAL PATTERNS 

Dental topography in all of the island forms is relatively simple. The enamel valleys 
between major cusps generally are unobstructed except for styles. The most common 
accessory tooth structures are ectostylids on the lower molars (Mi and Mi) and 
mesostyles on the uppers (Figs. 6, 7; Table 1 ); the latter are more variable in frequency and 
are found uncommonly on the second molars. Mesolophs occur at high frequency in the 
M ' only in mice from Islas Granito and San Esteban, whereas entolophs, mesolophids, 
and ectolophids were not observed in any specimens. A ''pseudomesolophid'' (Hershkov- 
itz, 1962) was observed in several specimens oi interparietalis on the lower first molar (two 
specimens |5.6%| from Isla San Lorenzo Norte and four [1 1.7%] from Isla San Lorenzo 
Sur). The mesoloph and mesostyle are rarely fused. This condition was observed on the M ' 
in only two (7.1 %) specimens o{ stephani and one (4.8%) o{ eremicus from Bahfa de los 



1971 LAWLOR: Peromyscus 97 



BAHIA DE LOS ANGELES 

28 
ZZl ISLA GRANITO 



3 



12 



II I ANGEL DE LA GUARDA 



17 

ID I SALSIPUEDES 



20 



SAN LORENZO NORTE C 



21 

I, SAN LORENZO SUR 



28 28 

ZZl I TIBURON I ~W W 1 



17 

m PUNTA SARGENTO 



160 180 200 220 80 100 120 

TOTAL LENGTH LENGTH OF TAIL 

Figure 3. Geographic variation of two external dimensions of Peromyscus on northern island and mainland 
areas in and adjacent to the Gulf of California, Mexico. The solid rectangles represent two standard errors on 
either side of the mean: hollow rectangles refer to the range of variation. Sample sizes are indicated for each plot. 

Angeles. 

Mice from the guard ia and interparietalis groups of islands exhibit the simplest dental 
topography in the upper molars, owing to the absence or low frequency of mesostyles, 
particularly in the M-. Populations of guardia differ from interparietalis by the nearly 
complete absence of mesostyles and entostyles on the M ' . In the lower molars there is little 
variation in frequency of ectostylids, but the mice from Isla Granito differ from the 
remainder of the island and mainland Peromyscus by virtue of the high frequency of 
mesostylids there. 

On the basis of dental structures Peromyscus from Islas Granito and San Esteban are 
the most distinct of the island forms. In addition to possession of mesostylids, the mice 
from Isla Granito have a high frequency of mesolophs on M' . Also, a mesoloph on the M- 
was noted in 20.8% of the specimens; except for its occurrence at very low frequency in the 
population from Bahia de los Angeles, this structure was not observed on the M- in 
specimens from other localities. The mice from San Esteban resemble those from Granito 
in having a high frequency of mesolophs on the M' . However, the population differs from 
that on Isla Granito by the absence of mesolophs on the M" and the presence of mesostyles 
on the M' in 25.0% of the specimens. In general, populations from Islas Turner and 
Tiburon resemble mainland populations o{ eremicus. 

Little phylogenetic information can be derived from the variation in dental patterns. 
For comparison, two mainland populations of eremicus from Bahfa Kino and Punta 
Sargento, Sonora, show as much variation in frequencies of mesostyles, entostyles, and 
ectostylids as do all other island and mainland populations studied; yet, these mainland 
localities are only 30 miles apart. Note also the variation in dental structure among the 



98 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 



1 


 




BAHIA 


DE LOS ANGELES L^ 1 

31 










32 




1 


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1 ISI A CRANirn 1  


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13 


13 

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1 


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14 


14 




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1 ANHFi nr 1 A nilARRA 1 ^H 1 




19 


21 


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V 

19 




m 


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^^ 






1 


 


1 


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W 1 




17 




24 




25 




1 1 


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1 


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1. TURNER 
1. TIBURON 

PUNTA SAR 

1 , 1 


V 

9 10 

□ 1 SAN ESTEBAN '-^^'^ 

16 


m 


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29 




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23.0 25.0 27.0 11.0 13.0 

LENGTH OF SKULL ZYGOMATIC BREADTH 

Figure 4. Geographic variation of two cranial dimensions of Peromyscus on northern island and mainland areas 
in and adjacent to the Gulf of California, Mexico. For explanation of plots see Fig. 3. 

three populations ofguardia (Figs. 6 and 7, Table 1). Similar variation was noted in several 
species of Peromyscus by Hooper (1957). His results for eremicus correspond closely to 
those presented for populations of that species here. 



QUALITATIVE CHARACTERS 

Osteology. — Variation in osteological characters among Peromyscus commonly is subtle, 
and distinct character differences often are difficult to detect in closely related species. The 
skulls of six island and mainland examples studied here are illustrated in Fig. 8. Eight 
cranial features of taxonomic importance were discernible in the island and mainland 
forms. Many of these features were observed by Banks (1967). The characters and their 
character states are as follows: 



1971 



LAWLOR: Peromyscus 



99 



15 



BAHIA DE LOS ANGELES 



15 



32 



ISLA GRANITO 



32 



14 



19 



^=f= 



21 



13 



I. MEJIA 



I ANGEL D£ LA GUARDA 



L SALSIPUEDES 



L SAN LORENZO NORTE 



13 

14 
19 



21 



17 



30 



18 




SAN ESTEBAN 



25 



10 



TURNER 



I TIBURON 



PUNTA SARGENTO 



17 



^¥^ 



30 



18 



8.0 10.0 

LENGTH OF ROSTRUM 



4.0 

LENGTH OF MAXILLARY 
TOOTHROW 



Figure 5. Geographic variation of two cranial dimensions o{ Peromyscus on northern island and mainland areas 
in and adjacent to the Gulf of California, Mexico. For explanation of plots see Fig. 3. 

(I) Shape of frontal bone (Fig. 8). — The posterior margin of this bone is curved 
(coded 0) in most of the island and mainland mice, but in certain populations (stephani, 
boylei) it usually is sharply angular (coded 1 ). 

(II) Position of nasal bones. — In stephani and boylei the nasals extend posteriorly to 
or beyond the premaxillaries (0) (Fig. 9A'), while in all other populations the nasal bones 
do not reach the level of the posterior extension of the premaxillaries (1) (Fig. 9A). 

(III) Shape of posterior margin of nasals. — The posterior margin of the two nasal 
bones is rounded or bluntly pointed (0) (Fig. 9A'), or squared (1) (Fig. 9 A). This character 
is variable among mice on the eastern Gulf islands and among mainland populations of 
eremicus. Squared nasals are particularly prominent among the three populations of 
interparietalis. 

(IV) Shape of interparietal bone. — Mice from populations of guardia exhibit a 



100 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



UPPER MOLARS 
Ml M2 



LOWER MOLARS 
Ml M2 



100 



50 



n 



a 



BAHIA DE 
LOS ANGELES (21) 



nl ms el es ml ms el es 



ml ms el es ml ms el es 



lOOrn 



50 



^ 
O 100 



Q. 



I GRANITO (24) 






50 



100 



n 



J] 







n 





50 



>- 



I ANGEL 
DE LA GUARDA (19) 



_a_ 



o 



100 



50 




100 



50 



n 



I SALSIPUEDES (35) 



H 



_n 



ml ms el es 



nl ms el es 



I SAN LORENZO 
NORTE (36) 



ml ms el es ml ms el es 



Figure 6. Frequencies of styles (stylids) and iophs (lophids) among Peromyscus on northern island and 
mainland areas in and adjacent to the Gulf of California, Mexico. Sample sizes are indicated in parentheses. Data 
for additional mainland populations are presented in Table 1. 

relatively small, triangular interparietal bone (0) (Fig. 9B), while the bone in remaining 
insular forms generally is strap-shaped ( 1 ) (Fig. 9B' and B"). 

(V) Lateral bony extensions of interparietal (Fig. 9). — Populations of guardia, 
boylei, and stephani commonly have small bony extensions of the interparietal bone that 
extend outward on each side toward the squamosals (1). The remaining island and 
mainland populations almost always lack these elements (0). 

(VI) Position of squamosals. — P. interparietalis, stephani, and boylei from Isla San 
Pedro Nolasco have relatively flattened skulls. The squamosal bones in these forms are 
slanted dorso-medially (1). This trait is not evident (0) in other populations examined and 
the skulls are inflated. This trait is indicated in Fig. 8 by the enlarged appearance of the 
squamosals. 

(VII) Shape of mesopterygoid fossa. — In most island and mainland forms the 
pterygoid bones adjacent to the fossa are straight (0) (Fig. 9C), but in guardia (Fig. 9C') the 



1971 



LAWLOR: Peromyscus 



101 



lateral pterygoid margins of the fossa are usually concave and as a result the fossa appears 
larger and is expanded laterally (1). The mainland population of eremicus from Presa 
Obregon, Sonora, also exhibits the latter feature. The occurrence of an expanded 
mesopterygoid fossa varies geographically within species. 

(VIII) Position of incisive foramina. — The incisive foramina in populations of 
interparietalis, coUatus, and certain eremicus commonly extend posteriorly beyond the 
level of the first molars (1) (Fig. 9C), while in other populations the posterior termination 
of the foramina is usually anterior to the molar toothrow (0) (Fig. 9C'). The values for this 
character are quite variable geographically. 



Table 1. Frequencies of occurrence of styles (stylids) and lophs (lophids) among some mainland 
populations of Peromyscus eremicus not included in Figs. 6 and 7. Entolophs (upper molars) and 
mesolophids and ectolophids (lower molars) were not observed in any specimens. Localities are 
arranged in order according to their number designation in Fig. 1. Numbers in parentheses identify 
sample sizes. 









Upper Molars 




Lower Molars 






X! 


u 


4> 


•o 


"O 






o 


B 


B 




">. 








CO 


■S! 


t/i 


-•-• 






1 


O 

CO 


1 


o 

CO 


s 






4> 


V 


■*-^ 


<o 


■*-» 


Locality 




S 


S 


c 


S 




Baja California 














Turtle Bay (6) 


Ml 


0.0 


83.3 


0.0 


0.0 


50.0 




M2 


0.0 


16.7 


0.0 


0.0 


50.0 


Barril (10) 


Ml 


0.0 


80.0 


0.0 


0.0 


90.0 




M2 


0.0 


70.0 


10.0 


0.0 


60.0 


San Francisquito (14) 


Ml 


7.1 


100.0 


21.4 


0.0 


85.7 




M2 


0.0 


64.3 


7.1 


0.0 


85.7 


El Marmol (10) 


Ml 


0.0 


70.0 


0.0 


0.0 


100.0 




M2 


0.0 


30.0 


0.0 


0.0 


100.0 


San Telmo (7) 


Ml 


14.3 


85.7 


0.0 


14.3 


71.4 




M2 


0.0 


85.7 


0.0 


0.0 


71.4 


California 














Escondido (13) 


Ml 


0.0 


92.3 


1.1 


0.0- 


84.6 




M2 


0.0 


69.2 


0.0 


0.0 


46.2 


Sonora 














Puerto Peiiasco (19) 


Ml 


0.0 


89.5 


36.8 


0.0 


94.7 




M2 


0.0 


73.7 


26.3 


0.0 


89.5 


Imuris (9) 


Ml 


0.0 


66.7 


0.0 


0.0 


88.9 




M2 


0.0 


11.1 


0.0 


0.0 


88.9 


Puerto Libertad (18) 


Ml 


0.0 


56.7 


50.0 


0.0 


61.1 




M2 


0.0 


38.9 


38.9 


0.0 


100.0 


Presa Obregon (11) 


Ml 


0.0 


63.6 


9.1 


0.0 


100.0 




M2 


0.0 


9.1 


0.0 


0.0 


91.0 



Mean values for coded character states are presented in Table 2. Although mean 
values of certain characters exhibit considerable geographic variation (see above) they 
have been included here to demonstrate the osteological variation that exists among 
different populations of certain species relative to that between species. Criteria for 
weighting such features are discussed below. 

It is evident that mice from Isla San Esteban are readily distinguishable from the 
remaining island populations on the basis of osteologic features. Further, stephani seems 
closest in these characters to boylei. Mice from the Guardia island group (guardia) are 
distinguishable chiefly by the triangular shape of the interparietal bone and the prominent 



102 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



UPPER MOLARS 
Ml M2 



LOWER MOLARS 
Ml M2 



100 



50 



100 



50 






ID 

X 100 

CL 

O 



Q 

<: 



50 



CO 

LU 

^ 100 

I— 

CO 

^ 50 



■>- 

o 






100 



50 





100 



50 



I SAN LORENZO 
SUR (34) 



ml ms el es ml ms el es 



ml ms el es ml ms el es 



II 



JZI 



I SANESTEBAN (28) 



I TURNER (30) 



JZL 



n 



_□ I TIBURON (36) 



PUNTA SARGENTO (16) 



\\ 



ml ms el es 



BAHIA KINO (8) 



ml ms el es 



ml ms el es ml ms el es 



Figure 7. Frequencies of styles (stylids) and lophs (lophids) among Peromyscus on northern island and 
mainland areas in and adjacent to the Gulf of California, Mexico. Sample sizes are indicated in parentheses. Data 
for additional mainland populations in Table 1. 

lateral bony extensions of the interparietal, while those from the Lorenzo island group 
{interparietalis) differ from other island and mainland forms chiefly by the squarish 
posterior margin of the nasals and the flattened braincase. The forms from Islas Turner 
{collatus) and Tiburon {eremicus tiburonensis) closely resemble mainland eremicus in all 
features. 

Post-cranial skeletons of all island and several mainland populations were examined, 
but no important variation in shape or position of bones was evident. However, differences 
in number of caudal vertebrae were observed (Fig. 10). Mice from mainland populations 
are more variable in this feature than those from the islands. In certain populations (e. g., 
guardia) the number of caudal vertebrae seems to be fixed. However, sample sizes 
generally are small, and conclusive statements must await additional data. 

Pelage. — Three pelage features were discernible. These characters and their character 



1971 



LAWLOR: Peromyscus 



103 






EREMICUS 



COLLATUS 



INTERPARIETALIS 



10 mm 






GUARDIA 



STEPHANI 



BOYLEI 



Figure 8. Dorsal skull views of six examples of Peromyscus from areas in and adjacent to the northern part of 
the Gulf of California, Mexico. 

States are as follows: (IX) extent of tegumentary attachment on the tail (skin tightly 
attached to underlying tissue, 0; skin loosely attached and easily removed, 1 ); (X) hairiness 
of the tail (scantily haired, 0; well haired, 1); (XI) occurrence of gray facial coloration 
(absent, 0; present, 1). 



104 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 





2 mm 





4mm 




Figure 9. Views of: the dorsal aspect of the frontal region of the skull in Peromyscus interparietalis (A) and P. 
stephani (A'); interparietal bones of P. guardia (B), P. interparietalis (B'), and P. stephani (B"); and midventral 
region of the skull in P. interparietalis (C) and P. guardia (C). For characters pertinent to these illustrations see 
text. 



1971 



LAWLOR: Peromyscus 



105 



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106 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 





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29 30 31 32 33 34 29 30 31 32 33 34 

NUMBER OE CAUDAL VERTEBRAE 

Figure 10. Number of caudal vertebrae in populations of P. eremicus and P. collalus (A), P. boylei and P. 
stephani (B), P. guardia (C), and P interparietalis (D). Letter designations are as follows: A — Isia Angel de la 
Guarda; B — P. boylei: CI. Turner; E I. San Esteban; G — I. Granito; I — I. San Lorenzo Sur; K — Bahia 
Kino; L — Bahia de los Angeles; M — I. Mejia; N — I. San Lorenzo Norte; S — I. Salsipuedes; T — I. Tiburon. 

Pelage characters serve chiefly to distinguish stephani and boylei from other forms. 
Only in stephani and boylei is the tail well haired and loosely attached. Pelage coloration is 
similar among the island and mainland mice, except that mice from Isla Mejia and Presa 
Obregon, where dark substrates occur, are darker than other populations. Few other 
pelage diff'erences are found among the remaining populations, although certain popu- 
lations (e.g., mainland eremicus) show considerable variation in the expression of gray on 
the face (Table 2). 

Morphology of phallus. — The island populations exhibit both complex and simple 
peromyscine phallic types (Figs. 11 and 12). Phalli of specimens from Isla San Esteban 
{stephani) are complex and closely resemble boylei in all features. Those of the remaining 
island forms and mainland eremicus are relatively simple. Accouterments, such as ventral 
and dorsal lappets, protrusible tip of glans, and cartilaginous tip of baculum, are poorly 
developed or absent. 

Specimens from the guardia group of islands have phalli that are morphologically 
intermediate between complex and simple types. A protrusible tip is present but not well 
developed, and dorsal lappets and a small cartilaginous tip also are present. Phalli of forms 
from Islas Tiburon and Turner, and the Lorenzo island group {interparietalis), closely 
resemble mainland eremicus, except that phalli of interparietalis are larger and six of seven 
interparietalis from Isla Salsipuedes and one of six eremicus from Bahfa de los Angeles, 
Baja California, have ventral lappets (see Fig. 1 1 and Table 2). It is not clear whether these 
structures in the two latter populations are homologous, however, because the lappets in 
the specimen from Bahi'a de los Angeles are separated from the adjacent tissue by a simple 



1971 L AWLOR: Peromyscus 111 

for eremicus, crinitus, and some populations of maniculatus by Brown and Welser 
(1968). The mobility for the three populations of interparietalis {ca. 94) also differs from 
the other forms studied here. In addition, the mobility obtained for albumin in boylei 
and stephani (90) does not correspond to the value (84) given for one individual of boylei 
by Brown and Welser, suggesting that an albumin polymorphism may exist in that species. 
Jensen (pers. comm.) has noted polymorphisms of albumin in boylei from northern 
Arizona. No intra-population variation was noted in this study. 

Although direct comparisons are not possible, the positions of the albumin band in 
interparietalis and guardia correspond favorably to densitometer tracings of this band 
(Brand and Ryckman, 1969) except that those authors report a difference between albumin 
of interparietalis from Isla Salsipuedes and from the San Lorenzos (a mixed sample from 
San Lorenzo Sur and San Lorenzo Norte). Further investigation of this discrepancy is 
required. 

Karyology. — All members of the genus Peromyscus so far examined have a diploid 
number of 48 chromosomes regardless of the proportion of acrocentrics in the complement 
(Hsu and Arrighi, 1966, 1968). The populations studied here are no exception. There also is 
considerable variation between species as regards morphology of the chromosomes. The 
populations examined here differ in the following characters (sample sizes given in Table 

2): 

(XXV) Number of autosomal acrocentrics. — There are no acrocentric chromosomes 
in merriami, eremicus. interparietalis, and collatus (0); most are either submetacentric or 
subtelocentric. P. guardia has one pair of small acrocentrics (1), while stephani and boylei 
each has 20 pairs (2). 

(XXVI) Morphology of the X chromosome. — In most populations, including 
merriami, eremicus, interparietalis, stephani, boylei, and guardia, this chromosome has 
unequal arms (0). Most have a large submetacentric X chromosome, but in guardia from 
Isla Mejfa it is a large subtelocentric. P. collatus has a large metacentric X chromosome 
(1). The morphology of this chromosome is subject to some variation both locally and 
geographically. For example, in eremicus it occasionally appears almost as a metacentric 
{cf Hsu and Arrighi, 1968), whereas in guardia it varies from a submetacentric to 
subtelocentric condition. Although this character is employed beyond for purposes of 
assessing overall similarity, additional data may prove it to be unsuitable for taxonomic 
use. 

(XXVII) Morphology of the Y chromosome. — This chromosome is a medium-sized 
acrocentric (0) in guardia, has unequal arms (1) in eremicus and merriami (medium 
subtelocentric), interparietalis and collatus (medium submetacentric), and is a medium 
metacentric in stephani and boylei (2). Hsu and Arrighi (loc. cit.) reported that the one 
individual of eremicus from Isla Tiburon they examined had a small acrocentric Y 
chromosome. However, examination of a photograph of that karyotype reveals that this 
chromosome is a subtelocentric according to the classification used here. 

The fundamental numbers of chromosomes in the island and mainland forms are: 
guardia 90, interparietalis 92, collatus 92, eremicus 92, merriami 92, stephani 52, boylei 52. 
Karyotypes are illustrated in Figures 15 and 16. 

BREEDING 

Attempted matings between different island and mainland forms are given in Table 3 . 
The breeding colony of interparietalis from Islas Salsipuedes and San Lorenzo Norte was 
obtained in 1967. Consequently more matings of those populations were made. Unless 
otherwise noted, results of crosses in the following discussion refer also to reciprocal 



112 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

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X Y 



XX ^^ ^^ Art GUARDIA (I MEJIA) ft ^ 



GUARDIA (I. GRANITO) 



u 



Figure 1 3. Karyotypes of P. slephani and P. guardia from Isla Meifa; and sex chromosomes of P. boylei. and P. 
guardia from Isla Granito. 




1971 L AW LOR: Peromyscus 113 

H n H H liil y 

jiji H hh n M KA ^/: 



AA i(X KK «A HA 



X Y 



||( M ^X XX INTERPARIETALS iJ ^ 



X Y 




n u n Hi' 



I II III IV 

I Figure 16. Karyotype of P interparietalis and sex chromosomes of P. eremicus from Bahfa de los Angeles (I) 
and Isla Tiburon (II), P. collaius (III), and P. merriami (IW). 

matings. All island forms o{ interparietalis bred freely among themselves, and one cross of 
interparietalis (?) and collatus (c?) was successful. In each case the offspring were viable. 
There was no success at breeding stephani, boylei, guardia, Tiburon eremicus, or collatus 
(except with interparietalis), even among controls. P. eremicus crosses, including one of 
Kino (?) X Bahfa de los Angeles (cf ), produced viable offspring in all cases. 

These results correspond well with data on attempted matings reported by Brand and 
Ryckman (1969); they were able to breed interparietalis and eremicus, but had very little 
success with guardia. The data indicate that certain island and mainland populations of 
eremicus, interparietalis, and collatus, are interfertile and are closely related. No con- 
clusive statements can be made concerning the negative breeding evidence for populations 
o{ guardia, eremicus tiburonensis, stephani, and boylei. Morphological features, such as 
those of the phallus, may act as physical barriers to hybridization with certain forms, P. e. 
tiburonensis, however, is obviously closely related to mainland eremicus and collatus; yet 
no mated pairs produced offspring. 

Evidence regarding laboratory breeding must be viewed with caution, since premating 
isolating mechanisms may break down under laboratory conditions. Nevertheless, since 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



certain forms have the potential for interbreeding in the wild, close relationship of those 
populations is evident. 

Table 3. Attempted matings of island and mainland Peromyscus. Numbers in parentheses repre- 
sent reciprocal crosses. 



S3 

< 





(/> 
































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60 

c 

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1) 




1 

3 

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o 

z 

o 


3 
CO 

o 




c 

a 

c 
on 




1 

o 
7, 


c 





o 




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tn en 


N 


N 








o 


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3 










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c 


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c 

o 

3 
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H 




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2 


M 

C 
< 


o 

'c 
a 

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nterpariet 
Salsipue 


o 

C 
C3 
CO 


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C 
03 

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■Jo 







FEMALES 

eremicus: 

Bahia Kino 

Bahia de los Angeles 

Tiburon 

coUatus: Turner 

guardia: 

Angel de la guarda 

Granito 

Mejia 

interparietalis: 
Salsipuedes 
San Lorenzo Norte 
San Lorenzo Sur 

stephani: 
San Esteban 

boy lei: 

San Pedro Nolasco 
near Tucson 



1 2(1) 1(0) 2(1) — 1(1) _ — __ — — — 

3 _ 1(1) _ 0(2) — — 2(1) 0(1) — — — 

2 1(1) _ — — — _ — — — — 

1 _____ 1(1) _ _ _ 

1 1(0) _____ — — 

2 1(1) — — 1(1) _ _ — 

1 ______ 

3 3(1) 2(1) _ — — 
6 2(3) _ — — 

2 0(1) 1(1) 

1 — 

2 



EVOLUTION OF THE ISLAND FORMS 

PHYLETIC RELATIONSHIPS 

A total of 27 serologic, karyologic, osteologic, and other morphologic characters was 
treated by numerical taxonomic methods, first by a phenetic clustering technique, and then 
by the quantitative phyletic method (Kluge and Farris, 1969). The first step is the 
construction of a Prim Network (Prim, 1957; Kluge, in press; see also Edwards and Cavalli- 
Sforza, 1964) in which only phenetic differences {sensu Farris, 1967) between the island 
and mainland populations, or OTU's (Operational Taxonomic Units; see Sokal and 
Sneath, 1963), are determined. Two Prim Networks are presented (Figs. 17 and 18). The 
character states used to describe the OTU's are sample means (data for every character 
were not available for all individual specimens). Distances between OTU's (interval lengths) 
represent the sums of character dilTerences between OTU's. The Prim Network connects 
the OTU's with minimum total interval lengths. There is no directionality implicit in the 
network, and angles of branching events are arbitrary. The first network (Fig. 17) includes 
data derived from all but serologic and karyologic characters. The second network (Fig. 
18) includes only those populations for which complete data were obtained (sufficient data 
regarding characters of chromosomes and blood proteins were not available for crinitus). 

Data regarding phalli for crinitus and mainland boylei and blood proteins and 



1971 



LAWLOR: Peromyscus 



115 



9 I San Pedro Nolasco 
1 30 
I San Esleban (slephani) 



2 16 



4.95 



4.51 



o o 

c c 

ra to 

c/) </> 



-•;♦ 



2 10 



88 

Kinol 



Pfesa Obregon 

f 

1 82 
1.02 



I ' * ' • 
^ I Tiburon 
I. Turner (collalus 



6.02 



t Mejia 



^H Granito 



1.03 036 1.161 

Bahia de los Angeles 



1.58 



I Angel de la Guarda 



■'boylei' 



interparietalis 



'"eremicus" 



guardia 



Figure 17. Prim Networlc computed from data derived from osteology, phallic morphology, pelage, and soft 
anatomy in Peromyscus on northern island and mainland areas in and adjacent to the Gulf of California, Mexico. 
The interval lengths represent unweighted measures of the sums of character differences between OTU's. The 
network length is 38.04. 

karyotypes for merriami were obtained from different populations than were data for other 
features in those species. Their inclusion is justified for comparative purposes because 
the above characters are relatively invariable geographically, and because even consid- 
erable variation in the above structures alters only the interval length and not the 
branching sequences. Consequently, the data are assumed to be representative. 

Four distinct clusters are evident in each diagram: (1) a group consisting of 
populations of mainland eremicus and insular forms from Tiburon and Turner (labeled 
"eremicus"); (2) a cluster comprised of the three island populations o{ interparietalis; (3) a 
group composed of the three island forms of guardia; and (4) a group consisting of 
mainland and island boylei (Tucson and Isla San Pedro Nolasco) and the population from 
Isla San Esteban (stephani) (labeled "boylei"). The populations of crinitus (Fig. 17 only) 
and merriami are located intermediate to boylei- and eremicus-Uke forms on the networks. 

The degree of phenetic similarity between the boylei-Vike forms and the remaining 
island and mainland forms clearly separates the former populations from the latter. They 
evidently are distantly related. Without doubt, stephani exhihhs closest affinities to boylei. 
To my knowledge, boylei glasselli (Isla San Pedro Nolasco) and stephani comprise the 
only two island derivatives of boylei in the Gulf. Note the differences in the Prim 
Networks, especially for populations of interparietalis and eremicus. that result from the 
addition of data on serology and karyology. 

In the quantitative phyletic method a Wagner Diagram (Farris, 1970) was used to 
depict interval lengths (patristic differences; sensu Farris, 1967) and branching events (Fig. 
19). The Wagner Diagram differs from the Prim Network in three ways: ( 1 ) each character 
is weighted a priori by the mean value of the reciprocal of the intrapopulation standard 
deviation over all OTU's (i.e., conservative characters are more heavily weighted; see 
Farris, 1966; Kluge and Farris, 1969); (2) hypothetical intermediates are generated to 
minimize total interval length (i.e., to maximize parsimony); and (3) a hypothetical 
ancestor is chosen, thus giving directionality to the diagraml The intervals on the diagram 
represent the sums of weighted character differences between OTU's. 

Populations representing eremicus, merriami, interparietalis, collatus, and guardia 
were examined for purposes of ascertaining phylogenetic relationships. These forms 
exhibit close morphologic and zoogeographic similarities and probably form a mon- 

'The character standard deviations, weighted character state values, and character state values for the hypothetical 
ancestor and generated intermediates, are filed with the National Auxiliary Publication Service of the American Society 
for Information Science, and may be obtained by ordering NAPS Document 01267 from ASIS National Auxiliary 
Publication Service, CCM Information Corp., 909 Third Ave., New York, N.Y. 10022, remitting $5 per photocopy or 
$2 per microfiche copy. 



116 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



interpanetalis 



^1, San Pedro Nolasco 

1.30 
^1 San Esteban {stephanO 

2 16 



o O 

c c 
o o 



— c c 

crt to to 



17.10 



103 36 



Presa Obregon 

\ 



• •! Turner (collatus) 



1 84 
3 10 



I 88 
2 16 



• 

mernami 



► Bahi'a de los Angeles 
902 



80 



I Mena 



1 68 
1 Angel de la Guarda 



I Granito 



"boyler" 



guardia 



Figure 18. Prim Network computed from data derived from all coded characters (features in Fig. 17 plus data 
from serology and karyology) in Peromyscus on northern island and mainland areas in and adjacent to the Gulf 
of California, Mexico. The interval lengths represent unweighted measures of the sums of character differences 
between OTU's. The network length is 48.63. 

ophyletic group. They are evidently only distantly related to boylei, crinitus, and other 
continental species not studied in detail here. Nineteen of the original 27 characters were 
used in this analysis. The other eight characters (II, IX, X, XVIII, XIX, XX, XXII, and 
XXIV) serve only to distinguish eremicus-Yikt forms from boylei-Wko, forms. Characters of 
Peromyscus eremicus were chosen as ancestral for eremicus-WkQ forms for the following 
reasons: ( 1 ) zoogeographically, eremicus represents the only species of Peromyscus that is 
present on the mainland of both sides of the Gulf, and it seems reasonable to assume that 
the island populations {QxcQ\)\.\r\g stephani) resulted from isolation of a mainland eremicus- 
like progenitor; and (2) the species shares the most characters in common with all the 
insular forms with the result that populations of this species are located centrally to other 
similar forms on the Prim Network. Assuming that evolution from a primitive ancestor 
takes place in more than one direction (i.e., it is radiative) and at approximately similar 
rates in major phyletic lines, then a population (or populations) located near the center of 
the Prim Network would seem to be the best approximation to the ancestral condition in 
the absence of unequivocal evidence. Thus, eremicus, or more likely a progenitor of similar 
characteristics, is here considered the ancestral type. Mean values of the character states 
for mainland populations o{ eremicus were given to the hypothetical ancestor. 

From the available data, it is not possible to ascertain which mainland eremicus are 
most like the ancestral form; all populations, and particularly those of P. e. eremicus, 
which occurs on the coastal areas surrounding the northern portion of the Gulf, are very 
similar morphologically. The close phenetic similarities of mainland populations result in 
the compact cluster on the Prim Networks (Figs. 17 and 18). On zoogeographic grounds, 
however, it seems likely that western island populations are derived from Baja Californian 
eremicus, whereas populations on the eastern Gulf islands are probably derived from 
Sonoran eremicus. The affinities of other mammals on eastern and western Gulf islands 
correspond closely to mainland species of the eastern and western sides of the Gulf, 
respectively (Table 4). Similar relationships are shown by peromyscines on other Gulf 
islands (Lawlor, in press), and by the amphibians and reptiles in the Gulf (Soule and Sloan, 
1966). 

It is clear from the phylogeny presented in Fig. 19 that, with the exception of 
merriami. interparietalis and guardia are the most divergent of the eremicus-Wkc forms. 
Populations from Tiburon {eremicus tiburonensis) and Turner (collatus) are not far 



1971 



LAWLOR: Peromyscus 



117 



I. Meiia 
0,38 



I. Angel de la Guarda 
"'—0.18 

Granito 




I Salsipuedes(23) 
0.92 
I San Lorenzo Sur 
'22-0.19 



Bahia Kino (21) 
19-0.33 



. 0.30 
^0 55 
005 
Hypothetical Ancestor 



Figure 19. Wagner Diagram depicting the phylogeny of closely related Peromyscus on northern island and 
mainland areas in and adjacent to the Gulf of California, Mexico. The interval lengths represent weighted 
measures of the sums of character differences between OTU's. Character state values for hypothetical 
intermediates generated during computation of the phylogeny are on file with NAPS (see text). The total length of 
the dendrogram is 24.08. 

removed from the hypothetical eremicus ancestor. P. guardia differs from other eremicus- 
Hi«ce forms in characters that are relatively invariable within species. Examples are the 
presence of band C hemoglobin, a triangular interparietal bone, and characters of the 
phallus. Conversely, interparietalis differs chiefly in features that often exhibit a high 
variance within species, such as the position of squamosals and shape of the posterior 
margin of the nasals. For instance, an inflated braincase owing to the position of the 
squamosals is observed in one of the two boylei populations examined (Table 2). Because 
of these differences in character state variation, guardia is more divergent from eremicus 
than is interparietalis. 

The phylogeny presented here as a working model can be used to examine evolution- 
ary changes in certain characters. For example, according to Hooper and Musser (1964a) 
and Hershkovitz (1962) simple conditions of the phallus (in Peromyscus these include the 
absence of a protrusible tip, lappets, and a cartilaginous tip on the baculum) and of the 
dentition (e.g., absence of accessory styles and lophs on the molars) are generally thought 
to result from loss of structures present in a more complex progenitor. Patterns of overall 
historical changes in these structures among island Peromyscus may not parallel trends in 
rodents in general. Nevertheless, the trends do differ from current views on the subject: (1) 
In guardia there evidently has been selection favoring both decreased and increased 
complexity of the teeth. There has been a virtual loss of mesostyles in all populations while 
in two populations mesolophs are present, and on one island (Granito) the frequency is 
100%. Selection has evidently acted to change the two structures independently and in 
opposite directions. (2) P. guardia also exhibits a relatively complex phallus (see above). A 
protrusible tip and dorsal lappets, although poorly developed when compared with those 
structures in boylei or crinitus, are present, which suggests that complex phalli can evolve 
from simple phaUi. Also, mice from Isla Salsipuedes (interparietalis) have developed 



118 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

ventral lappets. The evidence further indicates that acrocentric chromosomes are derived 
from bi-armed chromosomes in GuU Peromyscus. \n guardia, the Y chromosome and one 
pair of autosomes are acrocentric. No other island or mainland forms studied, other than 
crinitus (Hsu and Arrighi, 1968), boylei. or stephani, have acrocentric chromosomes, and 
in the latter species nearly the entire complement of chromosomes are acrocentric (only the 
sex chromosomes and three pairs of autosomes are bi-armed). 

Whether the trends noted above are characteristic of evolutionary changes of these 
features in other peromyscines or in other rodents is a moot question, but this may be the 
case in the development of accouterments in the phallus of P. eva (Lawlor, in press). The 
trends may represent reversals from the normal pattern of change in Peromyscus. In any 
event, the overwhelming evidence based on overall similarity indicates that the phalli, 
dentition, and chromosomes of guardia and interparietalis did evolve in the above ways. If 
the alternative hypothesis is invoked, namely that guardia and interparietalis are consid- 
ered derivatives of an ancestor having a complex phallus and dentition and a chiefly 
acrocentric chromosome complement (e.g., a crinitus-Wkt form), then convergences of 
many other characters must have occurred (e.g., osteologic and pelage characters, etc.). 
The latter seems highly unlikely. Moreover, the probability is quite low that such 
convergences occurred in all three populations of guardia while in stephani, which occurs in 
seemingly similar habitat on an island that is as well isolated and is of approximately the 
same age, none are observed. I regard the similarities of guardia and eremicus as indicators 
of genetic relationship and view the derivation of guardia in the most parsimonius manner, 
namely that it is derived from an eremicus-Wkt progenitor. 

Evidence from morphology of chromosomes and male accessory reproductive struc- 
tures suggests that eremicus and closely related species may share characters that are 
primitive for Peromyscus. Members of the subgenus Haplomylomys (excepting crinitus) 
are the only species having a complete complement of male accessory reproductive features 
(Linzey and Layne 1969). In all other species of the genus one or more elements are absent 
or vestigial. Except in guardia, acrocentric chromosomes are absent in mice of the 
subgenus. Although practically nothing is known about chromosome evolution in Per- 
omyscus, particularly in view of the fact that Robertsonian fusion cannot be invoked (Hsu 
and Arrighi, 1966; 1968), the data at least are not inconsistent with the view that the 
presence of acrocentrics is a derived condition. Hsu and Arrighi (1968) presented a 
hypothetical phylogeny of Peromyscus that describes the evolution of chromosomes as 
resulting from a primitive acrocentric condition, but they noted (p. 437) that the phylogeny 
was presented in that manner principally for convenience, stating that chromosome 
evolution in Peromyscus may have occurred in either direction. Information on muscula- 
ture (Rinker, 1963) also supports the view that Haplomylomys may be a primitive 
peromyscine group. Most of the conditions of the musculature that Rinker considered 
primitive are present in that subgenus. The evidence presented in this study suggests that 
complexities of the teeth and phallus derive from simple conditions and that acrocentric 
chromosomes derive from a bi-armed condition, at least in the species examined. Most of 
the Haplomylomys studied herein exhibit simple conditions of those structures. These data 
and those presented above support the contention of Linzey and Layne (1969) that 
Haplomylomys contains primitive members of the genus. 

HISTORICAL PERSPECTIVE 

The deserts of western North America, with which the origin and divergence of P. 
eremicus and related forms are closely associated, resulted chiefly from rain shadows 
produced by extensive mountain building in that area beginning in the Triassic and 



I 



1971 LAWLOR: Peromyscus 119 

continuing to the Pleistocene (King, 1958). However, adequate conditions to support 
lowland desert forms like eremicus probably did not exist prior to the formation of the 
North American deserts in mid-Pliocene (Axelrod, 1948). Undoubtedly these deserts were 
further modified by glacial advances and retreats during the Pleistocene, so that relatively 
stable desert conditions probably did not arise until early or middle Pleistocene, when 
successive glacial maxima became milder and interglacial periods were characterized by 
increasingly drier conditions. Displacement of desert elements by the Madro-Tertiary flora 
(e.g., thorn-scrub) during glacial advances in the early Pleistocene probably resulted in the 
separation of prototypes of merriami and eremicus and accounts for the differences in their 
habitat preferences today (Lawlor, in press). 

The history of the Gulf of California is not well documented. Although certain authors 
(e.g., Durham and Allison, 1960) consider the Gulf to be as old as the Cretaceous orogeny 
in North America and that it reached its present configuration by the beginning of the 
Pliocene, recent investigations of the southern Gulf floor (Larson et al., 1968; Moore and 
Buffington, 1968) suggest that the majority of crustal movement occurred since middle or 
late Pliocene. A proto-gulf is indicated, however, by earlier Pliocene fossil beds located in 
northern parts of the Gulf. In any case, the northern deep-water islands in the Gulf may not 
have originated until late Pliocene or early Pleistocene. For example, sedimentary beds of 
relatively recent deposition are known from the Lorenzos (early Pliocene) and Angel de la 
Guarda (late Phocene) (Anderson, 1950), indicating that the islands were submerged in a 
shallow water embayment or saline lake at the time. The geologic relationships of these 
islands to adjacent submarine troughs suggests that the islands may have resulted partly 
from elevation along faults (Shepard, 1950). Part of this uplift was probably Pleistocene 
(Ibid.). The present separation of Islas Tiburon and Turner from the Sonoran mainland 
was likely attained with the last glacial retreat {ca. 1 5,000 years ago). 

P. eremicus and related desert forms probably did not originate until formation of the 
deserts in mid-Pliocene. Consequently, evolution and radiation of this group on mainland 
and island areas has been relatively recent and no doubt has been substantially affected by 
displacement and expansion of the lowland deserts during the Pleistocene. In this 
connection, the suggested origin and radiation of these mice corresponds closely to that 
described for the lizard genus Uta (Ballinger and Tinkle, in press). 

ZOOGEOGRAPHIC RELATIONSHIPS 

Relationships between guardia, interparietalis, and eremicus are consistent with 
Banks' (1967) contention that guardia and interparietalis probably had separate origins 
from a mainland eremicus-Wkt stock. Furthermore, Peromyscus has not been taken on two 
islands (Isla Partida and Raza) that are located between the two groups of islands 
supporting guardia and interparietalis, although several people have collected on each (I 
have collected only on Isla Partida). This suggests that guardia and interparietalis do not 
represent isolates of a form once continuously distributed among these islands, but rather 
that they are of separate mainland origin (Ibid. ). 

The time interval between initial isolation of the island populations from the mainland 
is probably the principal factor affecting the degree of divergence of northern island forms 
in the Gulf of California. This seems to be the case for the following reasons: (1) 
Morphological divergence is at least broadly related to temporal differences in island 
formation. Angel de la Guarda and its satellite islands, the Lorenzo group of islands, and 
San Esteban have been separated from the mainland for a considerable length of time. 
Islas Tiburon and Turner most certainly are no older than late Pleistocene. P. eremicus- 
like forms on the older groups of islands (guardia and interparietalis) are more divergent 



120 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



than populations on younger islands (eremicus tiburonensis and collatus). (2) Apparently 
gene flow is minimal or absent among islands and between islands and the mainland. 
Differences persist among populations separated by very short distances, and because of 
habitat similarities and high population densities these differences probably are not 
attributable to presently existing differential selection coefficients or genetic drift. For 
example, it was pointed out above that populations from Islas San Lorenzo Sur and San 
Lorenzo Norte differ significantly (P<.05) in many morphometric characters; yet these 
islands are separated by 100 yards at most, and at low tide half-submerged rocks project 
above the water for almost the entire distance. Furthermore, ventral lappets on the phallus 
persist in most individuals of interparietalis from Isla Salsipuedes, while this feature 
evidently is absent in other nearby populations of that species. Isla Tiburon is separated 
from the Sonoran mainland by as little as two miles and by shallow water (only six meters 
at certain places); yet differences in phalli (and perhaps in karyotypes) are evident between 
the mice there and on the adjacent mainland (e.g., BahTa Kino); similar differences also 
persist between mice on Tiburon and those on Turner. In guardia. dramatic differences in 
dental patterns and morphometric characters are evident. It appears that distance effects 
owing to differential gene flow, although perhaps important in early colonization and 
establishment of the island populations, have been relatively unimportant in shaping 
present characteristics of the island forms. (3) Differences among island populations 
seemingly are not explicable only in terms of habitat differences. The northern part of the 
Gulf is marked by overall floral uniformity (Shreve and Wiggins, 1951; Felger, 1966). In 
addition, xeric rocky habitats are characteristic of all the islands inhabited by Peromyscus. 



Table 4. Zoogeographic relations of species of mammals on northern islands in the Gulf of California. 
Only island species having mainland relatives on one side of the Gulf are compared. No mammals other 
than Peromyscus stephani and Rattiis norwegicus are known from Isla San Esteban. 





65 
S 

.5 


1 

•S 


1 

1 




.1 


1 

E 






Cn 


Cg 


Co 


ex 


^ 


^ 


•I-* 




S 


s 


S 


4i 


^•l* 
Q 


6n 


c 




•s 


•s 


•5 


a 




.Si, 


■^ 


Locality 


1 


r 


<3 

1 


a 
1 


1 


"3 
to 
a 




a! 


a! 


a! 


^ 


:?: 


Q 


■-J 


Western islands: 
















Granito 


? 






? 








Mejia 


X 






? 








Angel de la Guarda 


X 






X 








Salsipuedes 


? 














San Lorenzo Norte 


X 














San Lorenzo Sur 


X 














Eastern islands: 
















Tiburon 




X 


X 




X 


X 


X 


Turner 




x> 


? 




X' 






Mainland: 
















Baja California 


X 






X 








Sonora 




X 


X 




X 


X 


X 



ifhis population originally was described as P. penicillatus (Burt, 1932) but evidently is intermedius (Patton, pers. 
comtn.) 
^Called N. varia, but closely related to albigula (Burt, 1932) 



1971 LAWLOR: Peromyscus 121 

On the basis of its degree of divergence and its phylogenetic relationships to merriami, 
guardia evidently has long been separated from an eremicus-WkQ ancestor. A prototype of 
merriami is thought to have arisen in early Pleistocene (see above) and the cladistic 
relationship between guardia and merriami indicates that they probably share a common 
ancestry. Thus, guardia probably represents a derived form of a stock that gave rise to 
merriami and that also colonized Angel de la Guarda and satellite islands in the early 
Pleistocene. P. interparietalis evidently is more recently derived from a mainland ere- 
micus-Yxko, form, possibly in middle to late Pleistocene. Mice from Islas Turner and 
Tiburon undoubtedly arose as a result of isolation of the two islands when the last major 
increase in sea level took place. P. stephani presumably has been isolated for some time 
(probably as long as interparietalis). It probably reached San Esteban from the eastern 
mainland during a glacial maximum in the Pleistocene when Isla Tiburon was part of the 
continent. Considering the present distribution of boylei, the initial colonization of Isla 
San Esteban by a boylei-\\V.Q form was probably also associated with more mesic habitats 
at that time. 

Early colonization and evolution of the island forms was likely erratic and unstable, 
and effects of distance between islands and the mainland, island area, and population size 
on genetic change were doubtless substantial. Once established, however, it appears that 
the island populations maintained their morphologic (and presumably genetic) integrity, 
and that the low rates of gene flow that obtain between the different island and mainland 
populations are unable to effect major changes in morphologic features. 

The presence of a particular species on an island appears to me to result from 
historical accident. I cannot explain the absence of an eremicus-Wko. form from an island 
like San Esteban, with its xeric, rocky habitat and floral composition similar to other 
Sonoran Gulf islands (Felger, 1966). Perhaps eremicus and boylei, or forms closely related 
to them, are competitors. Circumstantial evidence concerning the status of mice on Isla 
San Pedro Nolasco, where both boylei glasselli and an eremicus-Yxko, form (pembertoni) 
are known, suggests that boylei may be competitively superior io pembertoni. I collected 
there twice in the summer of 1967 and was unable to obtain pembertoni, although Burt 
(1932) look pembertoni and boylei in about equal numbers. This fragmentary information 
suggests that boylei may be supplanting pembertoni there, although the habitat, consisting 
of open slopes with cacti and low brush, and ravines of dense grass, is one of the most 
diverse of the northern islands. 

If the above evidence is indicative of a competitive superiority of boylei-Vike forms, 
then P. stephani, owing to its occurrence on Isla San Esteban, may have acted as a barrier 
to dispersal of eremicus-VikQ forms across the Gulf. Distinct morphologic differences do 
exist between eastern and western island eremicus-Wke forms (see above), suggesting few 
such crossings have been made. 

TAXONOMIC CONCLUSIONS 

I concur with Banks (1967) in considering interparietalis and guardia distinct from 
one another and from eremicus. Although interparietalis is evidently much less removed 
from the presumed eremicusAike ancestor than guardia, on morphologic and zoogeogra- 
phic grounds it seems worthy of specific status. On the other hand, collatus (Isla Turner) is 
very similar to mainland and Tiburon eremicus. Excepting the difference in the X 
chromosome, differences that separate the two species are subtle and are reminiscent of 
geographic variation exhibited by mainland populations of eremicus (Lawlor, in press). 
The mice from Isla Turner should bear the name P. e. collatus. The relationships of 
merriami and eremicus, based on osteology and morphology of the phallus, are discussed 



122 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

elsewhere (Lawlor, in press; see also Hoffmeister and Lee |1963], and Commissaris [1960]). 
The additional information regarding blood proteins and karyology and the phenetic and 
phyiogenetic relations of the two species presented here support earlier conclusions that 
merriami, although morphologically distinct, exhibits close affinities to eremicus and is 
probably derived from a progenitor similar to that species. All of the above species are 
members of the subgenus Haplomylomys. 

P. stephani clearly is a close relative of boylei and should be placed with boylei in the 
subgenus Peromyscus. In my view stephani should be retained as a species. 

ACKNOWLEDGMENTS 

For the loan of specimens 1 am indebted to the following individuals and their respective institutions: Dr. J. 
Knox Jones, Jr., Museum of Natural History, University of Kansas: Dr. E. Lendeli Cockrum, Department of 
Zoology, University of Arizona; Dr. Seth Benson, Museum of Vertebrate Zoology, University of California, 
Berkeley; Drs. Richard H. Manville and John L. Paradiso, United States National Museum; Dr. Joseph R. Jehl, 
Jr., San Diego Natural History Museum; Dr. Thomas R. Howell, University of California, Los Angeles; and Dr. 
Robert T. Orr, California Academy of Science. For manuscript review and counsel I am especially grateful to 
Drs. William H. Burt, Claude W. Hibbard, Donald W. Tinkle, Morris Foster, Emmet T. Hooper, and Arnold G. 
Kluge of the Museum of Zoology, University of Michigan; to Carl Welser, Mammalian Genetics Center, 
University of Michigan; and to Albert Bennett, intrepid explorer. I also extend thanks to my wife, Bertie, for help 
in preparation of the manuscript. 

Support for research and field investigations was provided in part by a U.S. Public Health Service 
predoctoral fellowship (No. l-Fl-GM-37, 761-01), by a grant to the University of Michigan from the National 
Science Foundation for research in Systematic and Evolutionary Biology (NSF GB-6230), and by a research 
grant from Sigma Xi. 

SPECIMENS EXAMINED 

Specimens employed for analysis of blood proteins and karyology were collected alive and maintained at the 
University of Michigan. Most of these mice are preserved in the Museum of Zoology, even though not cited 
below. Sample sizes and localities from which these specimens were obtained are given in the appropriate tables 
above. Only specimens obtained for purposes of examining morphologic features of the pelage, phalli, osteology, 
and soft anatomy are listed below. Where appropriate, numbers in parentheses identify the localities on the map 
(Fig. 1). 

P. boylei.— ARIZONA: Marble Park, Catalina Mts., Pima Co. (9), 24 (UMMZ). SONORA: Isla San 
Pedro Nolasco (14), 7 (UMMZ). 

P. crinitus.— CALIFORNIA: Paiute Creek, Inyo Mts.. Inyo Co. 28 (UMMZ). 

Z'. er?m/CM.?.— BAJA CALIFORNIA: Turtle Bay (1), 10(3 SD, 3 USNM, 4 UMMZ); Barril (2), 10 (SD); 
Bahi'a de los Angeles (3), 23 (2 SD, 1 UCLA, 20 UMMZ); San Francisquito (4), 16 (USNM); El Marmol (5), 14 
(CAS); San Telmo (6), 7 (UMMZ). CALIFORNIA: Escondido, San Diego Co. (7), 2 1 (KU). SONORA: Puerto 
Penasco (8), 20 (17 SD, 3 UA); Imuris (10), 9 (KU); Puerto Libertad (II), 20 (2 KU, 18 SD); Punta Sargento 
(12), 24 (UCLA); Bahfa Kino (13), 14 (2 UA, 6 KU, 6 UMMZ); Presa Obregon (15), 13 (10 KU, 3 UMMZ); Isla 
Tiburon,45(4CAS, 3 KU, 1 SD, 19 UC, 6 UCLA, 12 UMMZ); Isla Turner, 37 (1 CAS, 4KU,3SD, 15 UCLA, 
14 UMMZ). 

P. guardia. BAJA CALIFORNIA: Isla Angel de la Guarda, 28 (II SD, 10 UCLA, 7 UMMZ); Isla 
Granito,40(7SD, 33UMMZ); Isla Mejia, 17 (5 CAS, 3 SD, I UCLA, 8 UMMZ). 

P. interparietalis. - BAJA CALIFORNIA: Isla Salsipuedes, 48 (I CAS, 13 SD, 34 UMMZ); Isla San 
Lorenzo Norte, 41 (19 SD, 22 UMMZ); Isla San Lorenzo Sur, 46(7 UA, II CAS, 16 SD, 7 UCLA, 5 UMMZ). 

P. merriami.-^ SONORA: Presa Obregon ( 15), 20 ( 17 KU, 3 UMMZ). 

P. stephani. SONORA: Isla San Esteban, 37 (2 CAS, 1 SD, 19 UCLA, 15 UMMZ). 

The locality specified as "near Tucson" for boylei (Table 2) refers to Marble Park, Catalina Mts., Pima Co., 
Arizona, and Molino Canyon, 18 mi, NE Tucson, Catalina Mts., Pima Co., Arizona. The same designation 
(Table 2) for merriami refers to 3/4 mi. SE San Xavier Mission, Pima Co., Arizona. 

LITERATURE CITED 

Anderson, C. A. 

1950. 1940 E. W. Scripps cruise to the Gulf of California. Part 1. Geology of islands and neighboring land 
areas. Mem. Geol. Soc. Amer. 43: viii + 53 pp. 



1971 LA'WLOR: Peromyscus 123 

Axelrod, D. I. 

1948. Climate and evolution in western North America during the middle Pliocene time. Evolution 2: 127- 

144. 
Ballinger, R. E.. and D. W. Tinkle 

The systematics and evolution of the genus Uta (Sauria: Iguanidae). Misc. Publ. Mus. Zool., Univ. 

Michigan, in press. 
Banks. R.C. 

1967. The Peromyscus guardia-interparietalis complex. J. Mammal. 48: 210-218. 
Brand, L. R., and R. E. Ryckman 

1969. Biosystematics of Peromyscus eremicus. P. guardia. and P inlerparietalis. J. Mammal. 50: 501-513. 
Brown, J. H., and C. P. Welser 

1968. Serum albumin polymorphisms in natural and laboratory populations o{ Peromvscus. J. Mammal. 
49: 420-426. 

Burt. W. H. 

1932. Descriptions of heretofore unknown mammals from islands in the Gulf of California, Mexico. Trans. 
San Diego Soc. Nat. Hist. 7: 161-182. 
Commissaris, L. R. 

1960. Morphological and ecological differentiation of Peromyscus merriami from southern Arizona. J. 
Mammal. 41: 305-310. 
Durham, J. W., and E. C. Allison 

1960. The biogeography of Baja California and adjacent seas. Part I. Geologic history. The geologic history 
of Baja California and its marine faunas. Syst. Zool. 9: 47-9 1 . 
Edwards. A. W. P., and L. L. Cavalli-Sforza 

1964. Reconstruction of evolutionary trees. Syst. Assoc. Publ. 6: 67-76. 
Parris, J. S. 

1966. Estimation of conservatism of characters by constancy within biological populations. Evolution, 20: 
587-591. 

1967. The meaning of relationship and taxonomic procedure. Syst. Zool. 16: 44-51. 

1970. Methods for computing Wagner Trees. Syst. Zool. 19: 83-92. 
Pelger, R. S. 

1 966. Ecology of the gulf coast and islands of Sonora, Mexico. Ph. D. Thesis, Univ. Arizona, 460 p. 
Hershkovitz, P. 

1962. Evolution of neotropical cricetine rodents (Muridae) with special reference to the phylotine group. 
Pieldiana Zool. 46: 1-524. 

Hoffmeister, D. P. 

1951. A taxonomic and evolutionary study of the pinon mouse, Peromyscus truei. Illinois Biol. Monog. 21: 
X + 104 p. 
Hoffmeister, D. P., and M. R. Lee 

1963. The status of the sibling species Peromyscus merriami and Peromyscus eremicus. J. Mammal. 44: 

201-213. 
Hooper, E. T., and G. G. Musser 

1964a. The glans penis in Neotropical cricetines (Pamily Muridae) with comments on classification of muroid 

rodents. Misc. Publ. Mus. Zool., U. Michigan 123: 1-57. 
1964b. Notes on classification of the rodent genus Peromyscus. Occas. Papers Mus. Zool., Univ. Michigan 
635:1-13. 
Hsu, T. C, and P. E. Arrighi 

1966. Chromosomal evolution in the genus Peromyscus (Rodentia: Cricetidae). Cytogenetics 5: 355-359. 

1968. Chromosomes of Peromvscus (Rodentia: Cricetidae) I. Evolutionary trends in 20 species. Cytogenet- 
ics 7: 417-446. 

King, P. B. 

1958. Evolution of modern surface features of western North America. Publ. Amer. Assoc. Adv. Sci. 51:3- 
60. 

Kluge, A.G. 

The evolution and geographical origin of the New World Hemidactylus mabouia-brookii complex 

(Gekkonidae, Sauria). Misc. Publ. Mus. Zool., Univ. Michigan, in press. 
Kluge, A. G., and J. S. Parris 

1969. Quantitative phyletics and the evolution of anurans. Syst. Zool. 18: 1-32. 
Larson, R. L., H. W. Menard, and S. M. Smith 

1968. Gulf of California: a result of ocean-floor spreading and transform faulting. Science. 161: 781-784. 



124 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Lawior, T. E. 

1964. The Yucatan deer mouse, Peromyscus yucatanicus. Master's Thesis, Univ. Kansas, 45 p. 

Distribution and relationships of six species of Peromyscus in Sonora and Baja Cahfornia, Mexico. 
Occas. Papers Mus. Zool., Univ. Michigan, in press. 
Linzey, A. V., and J. N. Layne 

1969. Comparative morphology of the male reproductive tract in the rodent genus Peromyscus (Muridae). 
Amer. Mus. Novitates 2355:1-47. 
Matthey, R. 

1951. The chromosomes of the vertebrates. In: M. Demerec (ed.). Advances in genetics 4: 159-180. 
Mearns, E. A. 

1897. Descriptions of six new mammals from North America. Proc. U.S. Natl. Mus. 19: 719-724. 
Moore, D. G., and E. C. Butfington 

1968. Transform faulting and growth of the Gulf of California since the late Pliocene. Science 161: 1238- 
1241. 
Osgood, W. H. 

1909. Revision of the mice of the American genus Peromvicu.y. N. Amer. Fauna 28: 1-285. 
Patton, J. L. 

1967. Chromosome studies of certain pocket mice, genus Perognathus (Rodentia: Heteromyidae). J. 
Mammal. 48: 27-37. 

Preston, F. W. 

1962. The canonical distribution of commonness and rarity: Parts I and II. Ecology 43: 185-215 and 410- 
432. 

Prim, R.C. 

1957. Shortest connection networks and some generalizations. Bell Syst. Tech. J. 36: 1389-1401. 
Rasmussen, D. I., J. N. Jensen, and R. K. Koehn 

1968. Hemoglobin polymorphism in the deer mouse, Peromyscus maniculalus. Biochem. Genetics 2: 87-92. 
Rinker, G. C. 

1963. A comparative myological study of three subgenera of Peromyscus. Occas. Papers Mus. Zool., Univ. 
Michigan 632: 1-18. 

Shepard, F. P. 

1950. 1940 E. W. Scripps cruise to the Gulf of California. Part III. Submarine topography of the Gulf of 
California. Mem. Geol. Soc. Amer. 43: viii -f 32 p. 

Shreve, F., and I. L. Wiggins 

1951. Vegetation of the Sonoran desert. Publ. Carnegie Inst. Wash., 591: xii + 192 p. 
Smithies, O. 

1955. Zone electrophoresis in starch gels: group variations in the serum proteins of normal human adults. 
Biochem. J. 61: 629-641. 
Sokal, R. R.,and P. H.Sneath 

1963. Principles of numerical taxonomy. W. H. Freeman and Co., San Francisco, 359 p. 
Soule, M., and A. J. Sloan 

1966. Biogeography and distribution of the reptiles and amphibians on islands in the Gulf of California, 
Mexico. Trans. San Diego Soc. Nat. Hist. 14: 137-156. 
Townsend, C. H. 

1912. Mammals collected in Lower California with descriptions of new species. Bull. Amer. Mus. Nat. Hist. 
31: 117-130. 



Department of Biology, Humboldt State College. Areata, California, 95521 . 







LAMPETRA (ENTOSPHENUS) LETHOPHAGA, 
NEW SPECIES, THE NONPARASITIC DERIVATIVE 

OF THE PACIFIC LAMPREY 



CARL L HUBBS 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



VOL. 16, NO. 6 30 APRIL 1971 



LAMPETRA (ENTOSPHENUS) LETHOPHAGA, NEW SPECIES, 
THE NONPARASITIC DERIVATIVE OF THE PACIFIC LAMPREY 



CARL L. HUBBS 



ABSTRACT. — The Pacific lamprey, Lampetra (Enlosphenus) tridentata, is now shown to agree with 
most parasitic species of the Petromyzoniformes in having evolved into a nonparasitic derivative, L. (E.) 
lethophaga. Although the parasitic form ranges widely, from central Baja California around the North 
Pacific periphery to southern Japan, varying greatly in adult size, the dwarfed nonparasitic form seems to be 
confined to the contiguous drainage basins of the Pit River (a Sacramento River headwater) in northeastern 
California, both above and below the Pit River Falls, and to the upper Klamath River system in south- 
central Oregon. These two drainage basins harbor additional endemic fishes, and have certain other faunal 
features in common. The distributions of the three nonparasitic lampreys in the drainage basins around the 
North Pacific appear to be complementary. 

L. lethophaga contrasts rather sharply with the dwarfed, probably resident types of L. tridentata in the 
Klamath system, as well as with the large, sea-run populations. However, a specimen from Willow Creek in 
the Lost River system of Oregon is possibly intermediate between L. lethophaga and the dwarf parasitic 
types in the Klamath River system; and a parasitic form of the same group, of Miller Lake, in a disjunct 
section of the Klamath River system, is reported to be even more dwarfed than L. lethophaga. Some 
intergradation between the parasitic and nonparasitic stocks is not excluded. 

The dentition of the nonparasitic form exhibits features both of reduction and of increased individual 
variation, probably along with some geographical differentiation. 

Like other lampreys, the new species no doubt exists for several years in the larval (ammocete) stage 
before metamorphosing in the autumn. The gonads ripen as the gut atrophies. The dwarf adults after 
overwintering appear on circumstantial evidence either ( 1 ) to undergo the typical nuptial metamorphosis to 
spawn in the following spring, or (2) to attain maturity neotenically while retaining the prenuptial state of 
pigmentation and body form, and to spawn over the summer months, or even after overwintering again. 

There are indications that lamprey species are subject to regional diversity, and that some of the 
speciation has been of a mosaic type. 

RESUMEN. — Se demuestra que la lamprea del Pacifico, LMmpetra (Entosphetius) tridentata concuerda en su 
evolucion con la mayor parte de las especies parasiticas de Petromyzoniformes, produciendo un derivado no 
parasitico, L. (E.) lethophaga. Las formas parasitas presentan una amplia distribucion geografica, exten- 
diendose a lo largo de la zona periferica del Pacifico Norte, desde la parte central de Baja California hasta la 
zona meridional del Japon. Los adultos de estas formas ofrecen una gran variacion de tallas. Las formas 
enanas libres, no parasiticas, estan al parecer confinadas a las cuencas fluviales contiguas del rio Pit (uno de 
los tributarios de la parte alta del rio Sacramento) en la zona nordeste de California, a ambos lados de las 
cataratas del rio Pit, y en la parte alta del sistema del rio Klamath en la zona centro-meridional de Oregon . 
Estas dos cuencas fluviales albergan tambien otros peces endemicos, presentando asi mismo otras 
caracteristicas faunisticas comunes. Las tres lampreas no parasiticas que habitan las cuencas fluviales que 
bordean el Pacifico Norte, presentan al parecer una distribucion complementaria. 

L. lethophaga contrasta notablemente con las formas enanas, probablemente tipos residentes de L. 
tridentata en la red fluvial del Klamath, asi como tambien con las especies de talla grande correspondientes a 
poblaciones oceanicas. Sin embargo, un ejemplar procedente de Willow Creek, en la red fluvial del rio Lost, 
en Oregon, es posiblemente una forma intermedia entre L. lethophaga y los tipos parasiticos y enanos del 
sistema del rio Klamath. Una forma parasitica de este mismo grupo aparece en el lago Miller (seccion 
disyuntiva de la red fluvial del rio Klamath). Se ha establecido ya, que dicha forma es aun mas pequeiia que 
L. lethophaga. Desde luego no puede excluirse la posibilidad de que exista una intergraduacion entre las 
poblaciones parasitas y libres (no parasiticas). 

Las formas libres presentan variaciones individuals de reduccion o de incremento en la denticion, 
caracteristicas probablemente relacionadas con otras diferencias geograficas. 

SAN DIEGO SOC. NAT. HIST., TRANS. 16 (6): 125-164, 30 APRIL 1971 



126 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Al igual que sucede en otras lampreas, esta nueva especie permanece induablemente durante varies aiios 
en la fase larval {amoceto)antes de llegar a la metamorfosis, que tiene lugar en el otono. Al madurar las 
gonadas, el tubo digestive se atrofia. Los adultos enanos despues de pasar el invierno, evidencian cualquiera 
de las siguientes circunstancias: 1) que pasan la metamorfosis nupcial tipica para asi desovar en la 
primavera siguiente, o 2) alcanzan una madurez neotenica, es dicir, retienen la pigmentacion y forma del 
cuerpo de la fase prenupcial, desovando entonces durante los meses de verano, o aun mas tarde, despues de 
pasado el invierno. 

Las observaciones obtenidas indican que las especies de lampreas presentan dlversidad regional, y en 
algunos casos la especiacion corresponde al tipo de mosaico. 

Although I discovered a dwarfed, nonparasitic derivative of the Pacific lamprey, 
Lampetra (Entosphenus) tridentata (Richardson) in 1934, in the Pit River system of 
northern California and in the upper Klamath River system in southern Oregon, and 
although it has been distinguished by Bond (1961: 14) in key form from L. tridentata. from 
the same river systems, it has not yet been assigned a species-group name. Bond merely 
designated it "Klamath brook lamprey, Lampetra sp." With the particular need of making 
the name and the status of this form available for a forthcoming treatment of the 
distribution, phylogeny, and taxonomy of lampreys (Hubbs and Potter, in press), it is now 
belatedly made known as: 

PIT-KLAMATH BROOK LAMPREY 
Lampetra (Entosphenus) lethophaga, new species 

Entosphenus tridentatus (misidentification). — Rutter, 1908: 120 (material listed from 

"South Fork Pitt River" only). 
Lampetra planeri (misidentification). — Hubbs, 1925: 594 (size of recently transformed 

specimen from "North Fork of Pitt River"). 
Lampetra sp. — Bond, 1961: 14 ("Klamath brook lamprey"; "Klamath and Pit River 

systems"). 

Holotype, U. Mich. Mus. Zool. 130648, and paratypes, UMMZ 130649, from source 
of Fall River, a tributary to Pit River, in Shasta County, California (as specified under 
Location 2, below). 

This species is illustrated in Figures 1, 2 A-B, and 6; its range and habitat in Figures 3 
and 4; its size in Figure 8. Figures 2 C-D, 3, 5, 7, and 8 pertain in part or in toto to related 
forms. 

Diagnosis. — The following diagnosis largely follows the sequence of characters utilized by 
Hubbs and Potter (in press) in their analysis of the lampreys of the world. 

A petromyzonid lamprey agreeing with Lampetra (sensit lato) in having: the extraoral 
teeth not in regular alate rows, the lateral and posterior fields of disc essentially toothless 
between circumorals and marginals, the teeth of the anterior field few and scattered, none 
of the teeth villiform, the supraoral markedly dilated, the anterior circumorals normally 5, 
the total anterior and lateral circumorals usually 13, and the lateral circumorals more or 
less dilated. Agreeing with subgenera Lethenteron and Entosphenus in having the laterals 
connected by the posterior circumorals, and agreeing with Entosphenus in having 4 lateral 
circumorals on each side, one or more outer posterior circumorals often bifid, the 
supraoral often with a median cusp, the transverse lingual lamina almost rectilinear and 
with median cusp not strongly enlarged, and the marginals and posterior circumorals often 
in an irregular file. Differing from the complex now passing as Lampetra tridentata in 
being nonparasitic (not feeding or growing after the fall metamorphosis, but developing the 
gonads as the gut atrophies prior to spawning in the next spring or summer, or even later, 
and then dying), and in being much reduced in size at maturity (less than 170 mm), and in 
some places (including the type locality) breeding in prenuptial coloration and body form; 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 127 

also differing from L. tridentata in having the mouth small (disc length less than 5 percent 
of total length) and usually much puckered, the median cusp of supraoral often weak or 
absent, the cusps on the lateral circumorals often reduced by 1 on any of the four teeth 
from the formula 2-3-3-2, the posterior circumorals reduced in number (9 to 15), and 
the anterior intermediate disc teeth, between anterior circumorals and marginals, very few 
(only 4 in specimen shown for dentition as Figure 6). 

MATERIAL 

The considerable amount of material (Table 1) referred to Lampetra lethophaga has 
come from various places in the Pit River system of northeastern California and in the 
Klamath River system in south-central Oregon (Figure 3). The available information on 
the habitats at the 1 1 localities, 5 in the Pit system and 6 in the Klamath, and on the 
associated fish species and the circumstances of the collecting, is detailed because of the 
bearing that this information has on the interpretation of the distribution, environment, 
variation, and life history of the species. The localities are listed separately for the Pit and 
Klamath systems, in each basin from upstream downward. 

Material used in this study has been deposited in the following institutions: CAS, 
California Academy of Sciences; CU, Cornell University; OS, Oregon State University; 
SIO, Scripps Institution of Oceanography; SU, Stanford University (material now 
transferred to California Academy of Sciences); UMMZ, University of Michigan Mu- 
seum of Zoology; USNM, United States National Museum. 

LOCATIONS IN PIT RIVER SYSTEM, NORTHERN CALIFORNIA 

1. North Fork of Pit (formerly "Pitt") River at mouth of Joseph Creek, near Alturas, Modoc County, 
collected by Cloudsley Rutter and Fred M. Chamberlain, September 4, 1898. These data are taken from the label, 
but the specimens may have come instead from the South Fork of Pit River, for Rutter (1908: 120) failed to list 
the North Fork among the collections entered for "Entosphenus tridentatus." but did include it for "South Fork 
Pitt River (South Fork P.O., Jesse Valley"); also collected by Rutter and Chamberlain(the location of "Jess 
Valley," as now mapped at altitude of ca. 1585 m is located by a question mark on the distributional map. Figure 
3). In any event, it seems almost certain that Rutter's record was based on L. lethophaga. 

The 2 specimens (UMMZ 55316) making up this collection, received from Stanford University, comprise a 
female 142 mm long, in early stage of transformation, with eggs few enough to indicate a nonparasitic form, and 
an ammocete 105 mm long, with minute ova. The female was recorded as 138 mm long, under the 
xxwi\AQni\'acdiiox\ o{ Lampetra planeri. by Hubbs(1925: 594). 

Associated species reported by Rutter are, for North Fork, Catostomus occidenlalis Ayres, Rhinichthys 
osculus (Girard) subsp. (as "Agosia robusta"). and Salmo gairdnerii Richardson (as "S. irideus" ): and, for South 
Fork, Salmo gairdnerii. Rhinichthys osculus subsp. (as "Agosia robusta"), Gila bicolor (Girard) subsp. (as 
"Rutilus bicolor"), and Cottus pitensis Bailey and Bond (as "C gulosus"). This Coitus record has been referred 
by Bailey and Bond (1963: 20) to their new species, C. pitensis. which is endemic in the Pit and Little Sacramento 
river systems. 

2. Head of Fall River, in the west-central part of T 38 N, R 4 E, near the northeastern corner of Shasta 
County, close to the settlement of Dana and about 5 km north of Fort (Soldier) Mountain; altitude ca. 1020 m. 
This sizable stream (in the river proper about 50 m wide and uniformly about 0.7 m deep), flowed with a slight to 
moderate current. It originated in a partly forest-bordered, naturally ponded pocket of springs (Figure 4). Above 
the spring-fed origin of the river, the stream course (known as Bear Creek, though labelled "Fall River" on some 
maps) is intermittent; it was dry when examined in the very dry year of 1934. Locally we heard it claimed that the 
big springs arise from Tule Lake (presumably not the small "Tule Lake" close by to the east) and Lost River 
(both in the Klamath River system far to the north). However, it seems plausible that the source lies at least in 
part in the extensive lava beds immediately to the northwest, in southeastern Siskiyou County. 

This large cold stream has doubtless been a holdout, during periods of desiccation, of relict species. The 
stream, within 0.5 km of the springs, yielded, in addition to the lampreys, the endemic sculpin Coitus macrops 
Rutter (1908: 146-147, fig. 4) and C. asperrimus (misspelled "asperrima") Rutter (1908: 144-145, fig. 3), both 
closely related to endemic species of the Klamath River system. Rutter's list also included Salmo gairdnerii. 
along with dried remains of Catostomus occidentalis. from about a lateral spring, that indicated a prior breeding 
run of this sucker. The sculpin that Rutter (1908: 146) reported from Fall River as "C. gulosus" has been referred 
by Bailey and Bond to their C. pitensis. 



128 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 1. Types of Lampelra lethophaga. from head of Fall River, Shasta County, California (Location 2): A, 
holotype, UMMZ 130648, a mature, neotenic male 128 mm in total length, in side view. B, same specimen, in 
oblique view, with abdominal wall pinned aside, to show enlarged, lobular testis and atrophic gut bearing signs of 
hemorrhages. C, paratype, in series UMMZ 130649, a fully mature, neotenic female 1 16 mm long, in side view. 
D, same specimen, in oblique view, with abdominal wall pinned aside, to show celome packed full of ripe ova 
aligned in alate rows. 



1971 



HUBBS: A NEW NONPARASITIC LAMPREY 



129 





Figure 2. Nuptial males of genus Lampetra. subgenus Entosphenus: A, Lampetra lethophaga. OS 2856 
(specimen KOOlO), 154 mm in total length, in side view; from Crooked Creek, Klamath County, Oregon 
(Location 11). B, same specimen, in ventral view of head region, enlarged. C, Lampetra sp., seemingly 
intermediate between L. lethophaga and precocious forms of L. tridentata: SIO 65-144, 176 mm long, in side view; 
from Willow Creek, tributary to Clear Lake Reservoir, Modoc County, California. D, same specimen, in ventral 
view of head region, enlarged; with mouth pressed open. 



130 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

The water was so crystal clear that the bottom seemed to rise ahead. Vegetation comprised patches of 
Myriophyllum and very thick clumps of moss on lava rocks. The bottom in the stream was fine gravel and sand, 
with scattered lava rocks. The temperature was 11 .4° C in the current from a spring and 1 3.3° C in the river, when 
the air temperature was 29.4° C. The collection (M34-135) was made by Carl L. Hubbs and family on August 17, 
1934, using 4-foot and 6-foot Common Sense woven-meshed seines. One full-grown ammocete and 3 transformed 
adults came from weeds in the river; one adult was in muddy sand along the bank; the others, all adults, were 
taken under flat stones lying on clean, coarse gravel in the current from a lateral spring, mostly from under one 
stone where, when the stone was first turned, they looked like a breeding pod. 

The specimens taken at this station are the only ones designated as types. The holotype (UMMZ 130648), 
128 mm in total length, is a mature male (Figures lA-B). The paratypes (UMMZ 130649) comprise one male 
ammocete 130 mm long, 4 males and 5 females, nearly to quite ripe, 1 16-142 mm long, and one male that was 
taken partly decayed, within the same size range. A fully mature female, the smallest specimen, is illustrated 
(Figures IC D). 

On the basis of his field work Rutter (1908: 1 10) described Fall River and the adjacent part of Pit River as 
follows: 

The upper Pitt River, above the mouth of Fall River, was nearly dry in August, 1898. The water it 
contained was of a slightly milky color. The rocks at the bottom were covered with a spongy slime . . . 

At Fall River Mills, Pitt River receives Fall River, a stream about 100 feet wide and 4 feet deep, with a 
strong current, but only about 15 miles long. Fall River takes its rise in two or three large springs near 
Dana, and flows several times as much water as Pitt River above their union. The water is clear and cool 
and the bottom gravelly, making an excellent spawning stream for salmon, but difficult to attain on account 
of the steep rapid at its mouth, as well as the fall in Pitt River [see map. Figure 3]. 

Above the mouth of Fall River for a few miles, Pitt River is broad and deep, but without any perceptible 

current. Below the mouth of Fall River the character changes entirely. It is broad but shallow, very swift, 

with many rapids, and makes a rapid descent to the falls [3 km southwest of the mouth of Fall River]. Pitt 

River Falls, which are 65 feet high, are thought by many to rival in beauty any to be seen in Yosemite 

Valley. The middle portion is a sheer fall, but each side is broken by ledges, so that it is possible in high 

water for fish to pass. A fish ladder has been blasted out of the rock near the left bank, and salmon now go 

over the falls in considerable numbers. 

The falls do not delimit the distribution of Lampetra lethophaga (nor of the endemic Cottus pitensis Bailey 

and Bond, 1963: 20 25, figs. Id, 3b, 4d) in the Pit River system, but other Pit River endemics, Catostomus 

microps Rutter (1908: 120 121, fig. D), Cottus asperrimus, and C macrops do appear to occur only above these 

falls. 

3. Lower Hat Creek, below Highway 299 bridge, over a stretch of about 6 km, above Lake Britton (an 
artificially ponded section of Pit River), in northeastern Shasta County; altitude ca. 850 m. On October 4, 1968, 
lampreys by good fortune were taken and preserved during a massive poisoning by the California Department of 
Fish and Game, for the removal of "rough"" fish, presumably in the hope of controlling predation on and 
competition with the favored gamefish. Dr. Roger A. Barnhart, Leader of the California Cooperative Fishery 
Unit at Humboldt State College, who participated in the operation, preserved the fine series of specimens that he 
has made available for the present study. Dr. Barnhart reported (pers. comm., 1970) that "the lamprey turned out 
to be quite numerous in this section of Hat Creek. . . . We turned up 2-3 brook lampreys in our fall electrofishing 
census last fall so apparently we did not obtain a complete kill of lamprey" (again by good fortune). 

The collection furnished by Dr. Barnhart comprises 2 ammocetes 91 and 144 mm and 107 transformers 134- 
199 mm long, of which 12 transformers (SIO 71-8) are retained at Scripps Institution. Nine other specimens (2 
ammocetes 56 and 91 mm long and 7 transformers 146- 178 mm long; CAS 13391 ) were collected by Leonard O. 

Figure 3. Natural lakes and streams of the entire Pit River drainage basin and the upper part of Klamath River 
system, showing all known Locations, numbered 1-11, for the nonparasitic Lampetra lethophaga; also some 
waters inhabited by parasitic forms of the same subgenus in the Klamath basin. The collection stations for 
samples of the precocious stocks of L. tridentata utilized in this report are shown at A, for Shasta River near 
junction with Klamath River; B, for Klamath River at Klamathon; and C, for the Copco Lake impoundment of 
Klamath River. Shown also are nearby waters of contiguous drainage basins. Two of the largest of the many 
marshes in the area are Klamath Marsh (KM) and Sycan Marsh (SM). 

Map based largely on the United States Geological Survey 1:500,000 state maps of Oregon and California 
and on the following National Topographic Maps of the 1:250,000 series: Medford, Crescent, Klamath Falls, 
Weed, Alturas, and Susanville (1955-1963). The natural limits of South Klamath Lake, Tule Lake ("Rhett Lake" 
on some old maps), and Clear Lake (of the Klamath system) and of the seldom attained outlet stage of Goose 
Lake are taken chiefly from three old one-degree U.S.G.S. topographic sheets 1:250,000: Klamath, Oregon 
(1894), and Alturas and Modoc Lava-Bed, California (1892). The Map of the Lake Region of Southeastern 
Oregon by Snyder (1908a) was also used. 



1971 



HUBBS: A NEW NONPARASITIC LAMPREY 



131 



Fisk and W. E. Schafer of the California Department of Fish and Game during the same poisoning. 

4. Pit River at Pit 4 Powerhouse, in northeastern Shasta County, 20 km northwest of Burney and 1 km south 
of Oregon line; altitude ca. 650 m. One transformed female (CAS 25959), 155 mm long, with developing eggs; 
collected by W. Rowley with electric shocker on June 2, 1953. 

5. This number comprises two collections, only approximately located, in the same general area along Pit 
River, in Shasta County; altitude ca. 550 m: 



UMPQUA RIVER 
123° 



COLUMBIA RIVER 
122° 



INTERIOR DRAINAGE 

21° 120° 



ca 
> 

< 
o 

Q. 

3 



> 

cr 



3 
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o 
cc 



5 

kJ 
(- 
CO 

>- 
en 



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cr. 



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O 

O 
X) 
> 



> 
O 

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in 



SACRAMENTO RIVER SYSTEM 

10 20 



INTERIOR DRAINAGE 



40 MILES 



10 



20 



40 



60 KILOMETERS 



132 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 







Figure 4. Spring source of Fall River, in naturally ponded pocket of springs immediately above origin of stream 
flow (the type locality of Lampetra lethophaga); Location 2 on distribution map (Figure 3). Photograph by Laura 
C. Hubbs, August 17, 1934. 



5A. Near Big Bend, collected May 3. 1944 (no further data): 7 ammocetes (CAS 13392), 52-124 mm long; 
ova developing in largest one. 

5B. Between Pit 5 Powerhouse and Pit 5 Dam, collected June September, 1953 by William Rowley, Brian 
Curtis, and W. O. Cheney, of California Department of Fish and Game, by electric shocker: 1 ammocete (CAS 
25968), 63 mm long (identification presumptive). 

LOCATIONS IN KLAMATH RIVER SYSTEM, SOUTHERN OREGON 

6. North Fork of Sprague River, in east channel, about 1 km above junction with South Fork (prior to 
extensive disruption of stream course for irrigation), just east of east boundary of Klamath Indian Reservation, 
near center of west border of T 36 S, R 14 E, eastern Klamath County (Sprague River joins Williamson River 
just before that stream enters Upper Klamath Lake); altitude ca. 1340 m. Water moderately clear (bottom 
visibility about 1 m), shaded by 2-m banks, in pasture; some vegetation in patches; temperature cool; current 
moderate to swift; width ca. 5-8 m; depth ca. 0.7 m. The collection, M34-I20b, by Carl L. Hubbs and family, 
on August 9, 1934, with 25-foot bag seine, contained one adult male (UMMZ 130573) with maturing testis, with 
tail 43 mm long (front end missing; estimated original total length about 143mm) and one male ammocete, 91 
mm long, secured by much stranding of bottom material. Associated fish species were: Salmo gairdnerii. 
Catostomus snyderi Gilbert, Rhinichthys osculus klamathensis (Evermann and Meek), Gila caerulea (Girard), 
and Gila b. hicolor. 

1 . Sprague River opposite Ferguson Butte (in narrows of a broad valley), 6.5 km inside Klamath Indian 
Reservation, in T 36 S, R 13 E, Klamath County; altitude ca. 1325 m. Water moderately clear (bottom visibility 
ca. 1 m); water buttercup and other plants in dense patches; bottom mostly sandy, becoming dirty in weeds, some 
gravel, mostly tine, few stones; temperature cool; current mostly slight to moderate; width uniformly ca. 12 m; 



1971 



HUBBS: A NEW NONPARASITIC LAMPREY 



133 



depth to 1.2 m. The collection, M34-121, by Carl L. Hubbs and family, on August 10, 1934, with a 6-foot 
woven-mesh seine, contained a recently transformed male 145 mm long (UMMZ 130576), with testis developing 
and gut reduced, taken in dense vegetation. Associated species were Salmo gairdnerii. Rhinichthys osculus 
klamathensis. Gila caerulea. Gila b. bicolor. and Coitus klamathensis Gilbert. 

8. Tributary, near mouth, to upper course of Sycan River (affluent to Sprague River), at Pikes Crossing, 3 
km south of Currier Camp, near center of T 33 S, R 1 5 E, eastern Klamath County; just above a major canyon in 
river course; altitude ca. 1760 m. Water described as white, very slightly turbid, odorless; some green algae; 
bottom of sand, coarse gravel, and stones; 23.5° C (air 24.5° C); shore a sage flat, with meadow and timber; current 
swift in part; nearly 7 m wide in places and to 1.5 m deep. The collection, M 39-18, by Robert Rush Miller and 
Ralph G. Miller, on June 27, 1939, with 9-foot and 15-foot seines, contained an ammocete (UMMZ 136683) 132 
mm long, with small testis, and an adult female 106 mm long, somewhat bobtailed, with nearly ripe ova. 
Associated species, taken both in tributary and river, were Salmo gairdnerii and Rhinichthys osculus klama- 
thensis. 

9. Sycan River where it enters Sycan Marsh, at ZX Ranch, near center of T 32 S, R 14 E, in western Lake 
County; altitude ca. 1525 m. Water clear, whitish-brown, odorless; without vegetation; bottom of silt, rocks, and 
brush, largely scoured; 19.5° C (air 13°); willow thickets along shore, margining meadow; current none to slight; 
width to 5 m in pools; depth to 0.5 m. The collection, M 39 17, by Miller and Miller, on June 26, 1939, with 6- 
foot and 9-foot seines, contained (UMMZ 136678) an ammocete 121 mm long, with minute gonad, and a female 
110 mm long, with large ova. Associated species were Catostomus snyderi. Rhinichthys osculus klamathensis, 
and Gila b. bicolor. 

Dr. Robert Rush Miller was told by personnel at ZX Ranch that the expansive Sycan Marsh (SM, Figure 3) 
had no open springs and was not known to contain fish. However, it presumably passes fish in high water. 

10. This collection, comprising 2 spawning males (Cornell University 10296), 125 and 145 mm long, is 
labelled "Oregon, 5 mi. W. of Beatty, spring on S. side of road, Apr. 6, 1942, A. H. Wright." This places the 
station approximately 3—4 km south of midlength of Sprague River, near mid-west border of T 36 S, R 13 E, 
Klamath County; altitude ca. 1280 m. Dr. Wright stated (in letter of October 1, 1942) that: 

In a swampy area near a small streamlet west of Beatty, Oregon, 1 happened to find two clear, sandy 
areas about five or six feet deep. The swampy stretch was so treacherous that someone had laid boards 
across it and as 1 looked in the clear areas, . . . among the boiling sand were these two lampreys. It was a 
very striking spring with a very pronounced boiling sandy bottom. 

1 1. Klamath State Fish Hatchery, in the Klamath Indian Reservation, on Crooked Creek, a short spring-fed 
stream that joins Wood River close to Agency Lake; in Section 6 of T 34 S, R 7 Vi E, 4 km northerly from 

Table 1 . Mateiial of Lampetra lethophaga of different stages, arranged chronologically by day 
of collection 



Date of 
Collection 



Locality 
no. 



No. of specimens (and length in mm) at each stage 
Ammocetes Transformers 



Maturing and 
mature adults' 



1(142) 
114(134-199) 



6(130-160) 
6(132-154) 
1(137) 
2(125-145) 



1(155) 

1(110) 

1(106+) 



Feb. 16(1961) IIC — 

Mar. 13(1970) IID — 

Mar. 20(1970) HE — 

Apr. 6(1942) 10 — 

May 3 (1944) 5A 7(52-124) 

May 16 (1970) IIF 6(88-191) 

June 2 (1953) 4 — 

June26(1939) 9 1(121) 

June27(1939) 8 1(132) 

June-Sept. (1953) 5B 1(63) 

Aug. 9(1934) 6 1(91) 

Aug. 10(1934) 7 — 

Aug. 13(1934) llA 34(18-155) 

Aug. 17(1934) 2 1(130) 

August (1949) 11- 4(70-107) 

Sept. 4(1898) 1 1(105) 

Oct. 4(1968) 3 4(56-144) 

Oct. 20(1952) IIB 91(37-205) 

'Maturity indicated by boldface type for nuptial and postnuptial stages; by italic type for very definitely maturing 
stages, including, for the August 17 type series, some fully mature but not in nuptial color and form; and by 
roman type single specimens in earlier stages. 



l(ca. 143) 
1(145) 



11(116-142) 



134 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Klamath Agency, Klamath County: altitude 1280 m. Water very clear, arising in springs on hatchery grounds, 
close to upper part of Crooked Creek; with thick clumps of submerged vegetation; bottom of sand and pumice 
stones, with a little muck mixed with sand in the vegetation; shore grassy with some willows, in meadowland; 
7.8° C (hatchery personnel reported virtually no fluctuation); current moderate to, mostly, swift; width of rather 
straight course 4 8 m; depth to 0.6 m. 

This ecological description is based on observations on August 13, 1934, when Carl L. Hubbs and family 
collected 34 ammocetes (UMMZ 130606), 18 155 mm long, with a 6-foot fine-woven-mesh seine, by vigorously 
working through thick weed beds, muddy-sand bars, etc. None of the specimens showed any sign of 
metamorphosis, which may well take place late in this very cold water. The hatchery superintendent (W. I. 
How land) provided evidence that "runs of eels" do not occur in this or other local streams, and gave information 
on the local occurrences of lampreys. Some of the larger ammocetes show some development of ova and of testis. 
It was therefore concluded, on this initial contact, that the local lampreys are nonparasitic dwarfs. 

Associated with the ammocetes in the 1934 collection (M 34 126), in addition to Salmo gairdnerii and 
Salvelinus fontinalis (Mitchill) were sculpins, of the Klamath cold-water endemic species Cottus tenuis 
(Evermann and Meek), which was common. The superintendent had 3 or 4 large adults of Catostomus snyderi. 
which he said runs up Wood River and Crooked Creek in early spring. He indicated that still larger suckers, 
which from his description seemed to be Chasmistes. run chiefly up Williamson River, early in the spring, to 
spawn, and some go up Wood River. Eggs of these large suckers, he said, cover the bottom near wiers across 
Williamson River to a depth of several inches. When they come, the trout run ceases. 

Dr. Carl E. Bond (pers. comm., 1970) has received similar testimony regarding the local lampreys from 
personnel of the Klamath Hatchery. He has kindly provided me with additional specimens (listed in Table 2 as 
from Locations 1 1 B F), taken by and for them at the hatchery, in the ponds and their discharges ("after passing 
through the ponds, water is channeled into two ditches that run a short distance to Crooked Creek."). The 13 
adults examined in these lots, from Locations 1 ICE, are all in nuptial or postnuptial color and form (one, a 
partly spent male 154 mm long, the largest in 1 1 D, is illustrated as Figure 2A-B). Habitat data for the collection 
of March 20, 1970 (CEB 70-2; listed in Table 2 as from Location 1 IE), by Dr. Bond, Mr. Kan, and Richard 
Wilmot, by "sculpin net (frame net)" are: water clear, with Ranunculus, mostly at edges and behind stones; 
bottom of sand and line gravel, with few large stones; temperature 6.7° C; shore of masonry or stone; current 
moderate to slow; width 2.5 5 m; depth to 0.6 m. Lampreys taken in this collection were 2 ammocetes and 4 
adults (I alive and 3 dead), but the one adult received for study is a ripe male 137 mm long. 

ZOOGEOGRAPHICAL CONSIDERATIONS 

Like most but not all of the nonparasitic forms of lampreys, L. lethophaga lives within 
the range of its assumed parental type (see discussion of Life History, and Hubbs and 
Potter, in press). So far as known, it is limited to the upper parts of the Pit River system of 
the Sacramento River drainage in northeastern California and of the Klamath River 
system, adjoining, in south-central Oregon (Figure 3). This form, and/or parallel-derived 
nonparasitic types, may yet be discovered elsewhere within the wide range (Figure 5) of L. 
tridentata. but the only nonparasitic lampreys previously known to occur around the North 
Pacific are the derivatives of Lampetra (Lampetra) ayresii (Giinther) in the northeastern 
Pacific drainages (Vladykov and Follett, 1958, 1965), occurring as far south as the Santa 

Table 2. Material of Lampetra lethophaga from Klamath State Fish Hatchery received from 
Carl E. Bond and Ting T. Kan 



Locality 


Date 

collected 


Coll. 

no. 

(OS) 


Collector 


Number (total length, mm) 

Nuptial & 
Ammocetes postnuptial 


IIB 

lie 

IID 
HE 
IIF 


Oct. 20, 1952 
Feb. 16, 1961 
March 13, 1970 
March 20, 1970 
May 16, 1970 


2860 
2855 
2856 
2858 
2859 


Kenneth Cochrun 

Do. 
Ore. Game Comm. 
Bond, Kan, Wilmot 
Bond, Johnson, Kan 


25(77-189)' 




6(130-160) 
6(132-154) 
1(137)= 






6(88-191) 





'Kan measured 66 additional ammocetes, as 37-205 mm in total length, from this collection, which was sup- 
posedly taken by electrofishing, and 4, of 70-107 mm, collected at the same hatchery in August, 1949. These 
measurements have been included in the size-frequency graph (Figure 8). 
•Collection sheet lists for this set 2 ammocetes and 4 adults (1 alive and 3 dead). 



1971 



HUBBS: A NEW NONPARASITIC LAMPREY 



135 



Ana system of streams in southern California, and the derivatives of Lampetra (Lethente- 
ronj japonica (Von Martens), ranging from northern China and southern Japan through 
the coastal regions of Siberia to Alaska (and in northeastern North America). Sufficient 
material is known to render it highly probable that any other regional occurrences of any 
nonparasitic derivative of Lampetra ( Entosphenus) tridentata are at most few and 
limited. 

The known distribution of the nonparasitic lampreys around the North Pacific 
appears to be complementary. The ranges of the widespread nonparasitic representatives 
of the subgenera Lethenteron and Lampetra apparently do not overlap, and although L. 
lethophaga of the subgenus Entosphenus occurs about midway in the range of the Pacific- 
drainage representatives of subgenus Lampetra, no trace of that subgenus has been found 
in the Pit or Klamath systems, either by me, or by Carl E. Bond (pers. comm., 1971). 

It is noteworthy that no nonparasitic forms of the Entosphenus complex have been 
discovered in other parts of the long range of Lampetra tridentata around the periphery of 
the North Pacific (Figure 5), which extends southward from Bering Sea and Unalaska 
(Jordan and Gilbert, 1899: 434; McPhail and Lindsey, 1970: 58), and from Bering Island 
(Svetovidova, 1948; Berg, 1948, Addenda; 1962: 494). The limits of the known distribution 
of the parasitic form (or forms) have been expanded southward on both sides of the Pacific. 
On the American side it has been taken in streams as far south as southern California and 
in the ocean off Baja California, Mexico (Hubbs, 1967). On the Asiatic side there are 
several records from Japan, stated below. There seems to be no valid report of L. 
tridentata from the mainland of Asia (Lindberg and Legeza, 1959: 17-18 and 1967: 20- 
21), where L. japonica holds forth (the record of "Entosphenus tridentatus" from 
Kamchatka by Jordan and Evermann, 1900: 3231, pi. 1, fig. 4, was apparently based on the 
ammocete that was listed by Jordan and Gilbert, 1899: 434, from a river near Petropaulski, 
Kamchatka, as "Entosphenus camtschaticus," though on circumstantial grounds it seems 
more probable that it was an example of L. japonica). Okada and Ikeda (1938: 140 141) 























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120° 130' 140" 150° 160* 170* 
.AMBERT-S AZlMuTHflL EOUAL-AREA PROJECTION 


180° 


170" 160° 150° 110° 


130° 120° 


110° 


100° 


90° 


S0° 



Figure 5. Distribution of Lampetra tridentata around margin of North Pacific Ocean. Assumed usual range 
stippled; record stations beyond these limits ringed; area shown in Figure 3 indicated. 



136 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

initiated the Japanese records of L. tridentata by listing a specimen from Yahutugawa 
(river) in the Okhotsk Sea drainage of Hokkaido. Nemoto (1955: 69-70) stated the range 
of the species as "the broad region from the Arctic as far south as southern California and 
down to about 35° N Latitude in the western side of the Northern Pacific," but gave no 
supporting documentation for either the Arctic or for the southwestern limit, other than 
the questionable basis of finding, in the western North Pacific, whales bearing scars 
showing the tooth marks of I. tridentata. Aoyagi (1957), however, reported the capture of 
a specimen of this species in central Honshu, near 36° N latitude, in Kinugawa (river) at 
Atsutamura in Tochigi-ken. A further extension of range of the species has now come to 
light: Dr. O. Okamura has obtained a specimen from Yoshinogawa (river) on Shikoku 
Island in southern Japan; Tamotsu Iwai (pers. comm., 1970) has verified the identification. 
The occurrence of the nonparasitic representative of the Entosphenus group in the 
adjacent basins of the Pit and Klamath rivers is not unique, for these stream systems 
harbor a number of other endemic fishes, some of which are sympatric with Lampetra 
lethophaga. Klamath endemics were described by Gilbert (1898) and by Evermann and 
Meek (1898). One of these species, Catostomus rimiculus Gilbert (1898: 3) was described 
from the Klamath River system only but it was later found (Snyder, 1908b: 161) to inhabit 
also the Rogue River system, which adjoins the Klamath River drainage basin (Figure 3); 
it may well have crossed over the divide by some fluvial connection. The peculiarities and 
endemism of the Klamath and Pit river systems were summarized by Hubbs and Miller 
(1948: 67 71). Catostomus microps is a Pit endemic (Rutter, 1908: 120 121) and Cottus 
pitensis Bailey and Bond (1963: 20 24) is known only from drainages of the Pit River and 
the contiguous Little Sacramento River. An additional indication of residual endemism in 
the fish fauna of the area under consideration appears to be coming to light: Behnke (1970: 
241) has referred to "a group of previously undescribed trout native to several desiccating 
basins in southern Oregon extending to the Pit and McCloud rivers of northern Califor- 
nia." 

DESCRIPTION AND COMPARISONS 

The specifications, here adopted, of meristic and morphometric characters, involving 
definitions and methods, are essentially those proposed by Hubbs and Trautman (1937: 27 
-43, figs. 15). They have been adopted also by Hubbs and Potter (in press) in their 
account of the distribution, phylogeny, and taxonomy of lampreys. 

Chief concern pertains to the designation and to the method of counting of the lingual, 
oral, and disc teeth, which have been illustrated for Lampetra ( Entosphenus j tridentata by 
Hubbs (1947, fig. 3; 1963, fig. 2), by Vladykov and Follett ( 1958, fig. 1; 1965, fig. 1; 1967, 
fig. 2), and by Hubbs and Potter (in press, fig. 7). Special points regarding the cusps on the 
lingual laminae (one transverse and two longitudinal) and on the oral laminae (the 
supraoral and the infraorbital) are discussed below, in the description of the dentition. 

The concept of the circumoral row or series of teeth proposed by Hubbs and 
Trautman, primarily on the basis of the generalized dentition of Ichthyomyzon, seems 
quite applicable to the Entosphenus group, particularly because the posterior circumorals 
are so definitely aligned with the lateral circumorals, just outside the infraoral lamina. 
Furthermore, the lateral and posterior circumorals intergrade, through the frequent and 
unique bicuspid structure, and often through the increasing dilation outward, of one or more 
of the most lateral and most anterior of the posterior circumorals. Although the alignment 
of the posterior and lateral elements in a circumoral row is clear, the alignment and 
method of counting of the anterior connective is complicated by the tendency of all the 
anterior teeth in this group to alternate (in quincunx), so that a rather arbitrary distinction 
is involved, as is described below. The alignment and nomenclature of the inner disc teeth 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 137 

championed by Vladykov and Follett contrasts with the system of Hubbs and Trautman, in 
that the anterior circumorals are treated as the inner "anterials,"' the lateral circumorals as 
the "inner laterals" or "endolaterals/' and the posterior circumorals as the inner 
"posterials." 

Because dentition has traditionally and rightfully been emphasized in the systematics 
of lampreys, with added stress by Hubbs and Trautman (1937), by Vladykov and Follett 
(1967), and by Hubbs and Potter (in press), the dental laminae and teeth are here treated 
first. 

DENTITION 

Distinctive features of the dentition o{ Lampetra lethophaga outlined in the Diagnosis 
seem to make clear the relationships as well as the distinctness of this nonparasitic 
representative of L. tridentata. Exhibited are some features of reduction and some of 
increased variability. Reduction (often a concomitant of dwarfism) is indicated by the 
frequent degeneration, or loss (Table 3), of the median cusp of the supraoral (the tricuspid 
supraoral has usually been emphasized — often overemphasized — as the main feature of 
the genus or subgenus Entosphenus); by the occasional reduction of infraoral cusps to 4; by 
the frequent reduction (Table 4) by I cusp on any of the four lateral circumorals, from the 
normal Entosphenus formula of 2 3 3-2 (Figure 7); and by the low number (9-15) of 
posterior circumorals. The number of cusps in the transverse lingual lamina also seems to 
be reduced. Furthermore, the teeth tend to be reduced in size; the lingual and oral laminae 
and, in particular, the lateral circumorals, are all less dilated than in typical L. tridentata. 
and the other teeth tend to be smaller and less robust. Increased variability (commonly 
associated with degeneration) is shown strikingly by the number of cusps on the supraoral 
and, less certainly, by the number of infraoral cusps (Table 3), and, definitely, by the 
number of cusps on the lateral circumorals (Table 4). 

The small size of L. lethophaga and the weakness of its dentition render cusp counts at 
times somewhat difficult. Adequate magnification with strong illumination supplemented 
by a fine jet of compressed air may be called for. 

Although the full development of the teeth is a relatively transient feature, the cusps at 
early stages are sharp. In fact, it is difficult to determine from the teeth, at prime 
development, whether a specimen represents a parasitic or a nonparasitic form. The lingual 
laminae atrophy first, in concordance with the elimination of feeding. Of the disc teeth, the 
outer ones, between the circumorals and the marginals, appear to be the first lost. The 
degeneration of the anterior circumorals seems to follow soon; they become unrecog- 
nizable while the posterior circumorals remain sufficiently developed to be seen. The lateral 
circumorals are among the last to disappear, or to fragment. Completely spent individuals 
retain very little of their dentition, and the teeth do not seem to fuse into a cornified mass, 
as they do in L. tridentata. 

Lingual laminae. — In correlation with the reduced size of the laminae, the cusps are 
small — often minute, weak, and crowded. The median tooth of the transverse lamina is 
usually only weakly to moderately enlarged, and is somewhat variable: it is occasionally 
partly fused with an adjoining cusp on either side, and is rarely doubled. The transverse 
lamina is nearly rectilinear, with only the outer ends curved backward. The number of 
cusps in this lamina is probably reduced, totally only 12-19 in the 11 countable laminae, 
with a mean of 15.6 (12 17, averaging 14.75 in 8 from Pit River, 19 in two from the Sycan 
River, and 16 in one from Crooked Creek). The counts for the 15 specimens from the 
Klamath River near Klamathon are higher, 21-27 (mean 23.3), and the one from Copco 
Lake has 22. However, the counts for 437 macrophthalmiae of L. tridentata from the 
mouth of Shasta River, not far distant, are intermediate: 14 23 (mean 1 8. 1 ). McPhail and 
Lindsey (1970: 57) described the lamina of L. tridentata as having "about 15-25 fine 



138 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



points, the median one scarcely larger than the others." 

The cusps on the longitudinal lamina are also minute and relatively very numerous. 
They were not counted. McPhail and Lindsey ( 1 970: 53) stated that "£". tridentatus has 50- 
63 fine points on each longitudinal lingual tooth plate, in contrast to 0-26 points in all 
Lampetra species examined," and they regarded this distinction as one basis for the 
recognition of Entosphenus as a distinct genus. The number of cusps no doubt varies, and 
the "O" counts presumably represent laminae that have been shed, probably postnuptially. 
The other basis given for the recognition of Entosphenus was the number and arrangement 
of the velar tentacles — a feature (not checked by me) that hardly seems of generic 
significance, though seemingly trenchant on the species level. 








<s> "^ 







jj-'-- 



Figure 6. Dentition of Lampetra lethophaga. from mature female paratype 1 16 mm long, shown in Figures 1 C, 
D; note oral papillae as well as fimbriae; development of bicuspid posterior circumorals is extreme in this 
specimen. 

Oral plates (Table 3). — The oral plates are somewhat more delicate and less dilated 
than in the parasitic forms oi Entosphenus. 

As noted above, the supraoral plate (or tooth) often fails to exhibit the strongly 
tricuspid form traditionally used to diagnose Lampetra tridentata, for, in each river 
system, the median tooth is more or less reduced in size, down to a mere rudiment, or is 
altogether missing. Bicuspids and tricuspids are about equal in frequency, and quadricus- 
pids are occasional. Thus, the supraoral-cusp pattern is much more variable than is usual 
in Entosphenus. Ordinarily, in L. tridentata, the tooth is tricuspid, as it is in every one of 
the 437 macrophthalmiae counted from the mouth of Shasta River, in all 1 5 adults from the 
Klamath River, in the one from Copco Lake, and (Mr. Ting T. Kan, pers. comm., 1971) in 
all 86 adult specimens of the dwarf race from Miller Lake. In L. lethophaga, as a further 
indication of variability, the third cusp is occasionally well to one side of the midline, and 



1971 HUBBS: A NEW NONPARASITIC LAMPREY I39 

the 3 quadricuspid plates exhibit different cusp patterns: 2 + 2, 1 + 1+2, and 2+1 + 1 (left-to- 
right). 

Bond (1961: 14) distinguished the nonparasitic form (his ""Lampetra sp.") from L. 
tridentata too sharply, as having "teeth dull, supraoral lamina with two widely separated 
cusps" rather than having "all teeth sharp and functional, supraoral lamina with 3 cusps." 
This seems to be the commoner condition only in Crooked Creek (Table 3) from which Dr. 
Bond had specimens of the new form. 

The cusps on the infraoral plate average nearly as numerous in L. lethophaga as in the 
precocious stocks of/., tridentata from the Klamath River system. Six among 56 specimens 
have only 4 cusps, whereas reduction below 5 was not encountered among the 453 



J-.'^"-*^-^''-*-""  

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Figure 7. Generalized illustration of dentition of Lampetra tridentata, drawn, with mouth somewhat puckered, 
by Elizabeth M. Kampa; used as basis for figures in Encyiopaedia Britannica (Hubbs, 1947, fig. 3: 1963, fig. 2). 

specimens of Z,. tridentata listed in Table 3, nor in any of the counts for the Trinity and Eel 
rivers in northern California. The cusp count was increased in L. lethophaga to 6 or 7 in 
only 7% of the specimens, but in the L. tridentata specimens here tallied, to 12% in those 
from Shasta River and to 33% in those from Klamathon; and the one from Copco Lake 
has 6 infraoral cusps. Counts higher than 5 may result either from a regularly spaced series 
or from the interpolation of a small supernumerary cusp toward one end of the plate. The 
outermost cusp of each side is strengthened but is never doubled, as it typically is in 
subgenus Lampetra. The specimen of doubtful identification from Willow Creek and (Ting 
T. Kan, pers. comm., 1971) the Miller Lake lampreys have the usual cusp pattern for the 
oral teeth (3 and 5, respectively). 

Circumoral teeth and cusps (Tables 4-6). — Some of the sharpest distinctions of L. 
lethophaga involve these teeth and their cusps, on the lateral and posterior fields of the 
disc. 



140 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Anterior circumorals.— As in L. tridentata. the anterior circumorais are typically 
countable as 5, on the criterion that any anterior tooth is interpreted as a circumoral that 
approximately reaches or passes behind the imaginary arcuate line passing through the 
centers of the teeth of the definitely inner-marginal row. The tendency of the anterior oral 
teeth to alternate so as to approach a quincunx arrangement renders the inclusion or 
exclusion of a given tooth from the anterior-circumoral series somewhat difficult and 
rather arbitrary. Another uncertainty is introduced by the tendency for the anterior disc 
teeth to atrophy rapidly in this species. The counts recorded are 5 for 14 specimens, 

Table 3. Counts of cusps on oral plates in Lampetra lethophaga and in Klamath River preco- 
cious populations of L. tridentata 



Oral plate 

Species 

River system (No.)' 
Locality (No.)' 



Number of cusps per oral lamina 



7 Mean 



Supraoral 

L. lethophaga 
Pit (10) 
Spraeue (5) 
Crooked (13) 
Total (28) 

L. sp. 

Willow ( 1 ) 

L. tridentata 

Klamath (453) 

Shasta R. (437) 
Klamathon (15) 
Copco L. ( 1 ) 



3 

2 

8 

13 



5 

3 

4 

12 



437 

15 

1 



2.90 
2.60 
2.46 
2.64 



3.0? 



3.000 

3.00 

3.0? 



Infraoral 

L. lethophaga 

Pit (10) 
Sprague (5 ) 
Crooked (13) 
Total (28) 

L. sp. 

Willow ( 1 ) 

L. tridentata 
Klamath (453) 
Shasta R. (437) 
Klamathon (15) 
Copco L. ( 1 ) 



9' 

2 
10 
21 



382 


41 


10 


5 




1 



- 4.90 

1 5.40 

1 5.15 

2 5.11 



5.0? 



14 



5.158 

5.33 

6.0? 



'Number of specimens. 
^Value for holotype. 

doubtfully 5 for 7, 6 for 3, and 7 for 2. The anterior circumorais are counted as 5 also in the 
Willow Creek specimen of doubtful identification. 

Lateral circumorais (Table 4). — A striking feature of L. lethophaga, already alluded 
to, is the strong tendency for the number of cusps to decrease by 1 in each of the 
consistently 4 lateral circumorais, on each side, from the standard, usually almost 
invariable, formula of 2-3-3 2 in L. tridentata. The ratio of reduced counts to the full 



1971 



HUBBS: A NEW NONPARASITIC LAMPREY 



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142 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



complement, for each of the teeth, counted from the front on each side, for each of the 
three stream systems, is as follows: 

First tooth 0:20 (Pit), 4: 10 (Sprague), 4:22 (Crooked). 

Second tooth — 9:20 (Pit), 5: 10 (Sprague), 1 8:22 (Crooked). 

Third tooth — 18:20 (Pit), 6: 10 (Sprague), 20:22 (Crooked). 

Fourth tooth 0:20 (Pit), 2:10 (Sprague), 8:22 (Crooked). 

The Willow Creek specimen agrees with L. tridentata in the formula of 2-3-3-2. 
The same formula, with little variation, holds for the dwarfed, reportedly parasitic Miller 
Lake lamprey (Carl E. Bond and Ting T. Kan, pers. comm., 1971). 

Posterior circumorals (Tables 5, 6). — One of the dentitional features that most 
clearly points to the derivation of A. lethophaga from L. tridentata is the frequent bicuspid 
structure of the more lateral of its posterior circumorals (Figures 6, 7), involving teeth 
occasionally as far from the end as the seventh (Table 5). Lampetra tridentata is the only 
previously known lamprey of the Lampetra type that has such bicuspid teeth in the 
posterior commissure, and this tendency is notably characteristic of the precocious Klamath 
River types that may well have been ancestral to L. lethophaga. In fact, in those types the 

Table 5. Counts of cusps on individual posterior circumoral teeth in Lampetra lethophaga and 
in the Klamath River precocious populations of L. tridentata 



Species 

River system (No.)' 
Locality (No.)' 


Tooth No. V 
U/B Mean' 


Tooth No. 2' 
U/B— Mean' 


Tooth No. 3' 
U/B Mean' 


Tooth No. 4^ 
U/B Mean'' 


L. lethophaga 
Pit (20)* 
Sprague (10) 
Crooked (18) 
Total (48) 
L. sp. 

Willow (2) 
L. tridentata 
Klamath (906) 
Shasta R. (874) 
Klamathon (30) 
Copco L. (2) 


8/12—1.60 

8/2—1.20 

17/1—1.06 

33/15—1.31 


7/13—1.65 

8/2—1.20 

18/0 1.00 

33/15—1.31 


14/6 1.30 

8/2—1.20 

18/0 1.00 

40/8 1.17 


18/2—1.10 

8/2—1.20 

18/0 1.00 

44/4 1.08 


0/2—2.0? 

213/661 — 1.756 
1/29—1.97 
0/2—2.0? 


1/1—1.5? 

549/325—1.372 
1/29—1.97 
0/2—2.0? 


2/0 1.0? 

835/39—1.045 
5/25—1.83 
0/2-2.0'? 


2/0 1.0? 

835/39—1.045 
14/16 1.53 
0/2—2.0? 


Species 

River system (No.)' 
Locality (No.)' 


Tooth No. 5= 
U/B— Mean-' 


Tooth No. 6' 
U/B Mean^ 


Tooth No. r- 
U/B— Mean^ 


Tooth No. 8= 
U/B Mean' 


L. lethophaga 
Pit (20)* 
Sprague (10) 
Crooked (18) 
Total (48) 
L. sp. 

Willow (2) 
L. tridentata 
Klamath (906) 
Shasta R. (874) 
Klamathon (30) 
Copco L. (2) 


18/2—1.10 
10/0 1.00 
18/0 1.00 
46/2—1.04 


19/1 — 1.05 
10/0—1.00 
18/0 1.00 
47/1 1.02 


19/1 — 1.05 
10/0 1.00 
18/0 1.00 
47/1 — 1.02 


20/0—1.00 
10/0 1.00 
18/0 1.00 
48/0—1.00 


2/0 1.0? 

872/2—1.002 
25/5—1.17 
0/2 2.0? 


2/0 1.0? 

873/1 — 1.001 
26/4 1.13 
0/2—2.0? 


2/0 1.0? 

874/0 1.000 
28/2—1.07 
1/1 — 1.5? 


2/0—1.0? 

874/0 1.000 
29/1 — 1.03 
0/2—2.0? 



'Number of sides counted (2 per specimen). 

'The teeth are numbered from the lateralmost and foremost; the ninth tooth is bicuspid on one side of the one 

specimen from Copco Lake. 

'U/B indicates the number of unicuspids and bicuspids, respectively, for each given tooth number. The numbers 

(and the means) are in a sense hypothetical, for it is assumed for all teeth more centrad than the fourth on 

either side that the tooth, unless bicuspid, would have been unicuspid had such a tooth been present: the total 

number of posterior circumorals may be as low as 9 in L. letliophaga and as low as 15 in the Klamath River 

precocious populations of L. tridentata: hence the tooth count on either side often passes beyond the midline into 

the series from the other side; the tooth number used assumes the arrangement of unicuspids and bicuspids that 

would have existed, had there been as many as 9 teeth on each side. 

*The holotype has the outermost 2 teeth on each side bicuspid. 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 143 

lateral teeth often grade, in position, size, and structure, almost imperceptibly into the 
outer members of the posterior series. The proportion of the outer posterior teeth that are 
bicuspid is greater in the Pit River sample than in the collections from Sprague River and 
Crooked Creek. Oddly, the degree of bicuspidity averages very distinctly higher in the 
dwarf adults of L. tridentata from the Klamath River near Klamathon than in the 
macrophthalmiae from the Shasta River near its junction with the Klamath, not far below 
Klamathon; and the one specimen from Copco Lake has 8 bicuspids on each side (a record 
number). In compensation, the unilateral posterior circumorals average fewer in the 
Klamathon lot than in the Shasta River specimens, and the one from Copco Lake has only 
3. One of the sharpest distinctions of L. lethophaga from the samples of L. tridentata from 
the Klamath River system lies in the lower total number of posterior circumorals, with 
very little overlap (Table 6). The alignment of the posterior circumorals tends to be slightly 
irregular in some specimens, though at the end on each side the series lines up very well 
with the posteriormost (fourth) lateral circumoral. 

In the numbers of circumoral teeth and cusps the one specimen of doubtful 
identification from Willow Creek shows some correspondence with L. tridentata and some 
features of seeming intermediacy between the two species. The total number of posterior 
teeth in the series (17) is 2 higher than any count for L. lethophaga and below the mean for 
the L. tridentata series. The number of unicuspid posteriors (14) is extreme for L. 
lethophaga and near the mean for L. tridentata. The number of bicuspid posteriors (total 
3) is not definitive. 

Outer disc and marginal teeth. — As in L. tridentata, the disc is consistently toothless 
between the circumorals and the marginals, except for a few rather scattered teeth (not 
counted) in the anterior field. The pattern of the marginal teeth, as in L. tridentata, in some 
specimens, weakly suggests that the marginal series may retain elements from the very tips 
of the recurved ends of the original alate rows — particularly in that some of the teeth tend 
to be rather larger and less completely at the disc edge than those preceding and following 
(see figures by Vladykov and FoUett and by Hubbs and Potter and the discussion by the 
latter authors). The marginal series, however, remains essentially complete and intact, 
whatever its origin may have been. 

In the Copco Lake specimen the marginals between the first and second and between 
the second and third lateral circumorals are much dilated, and are considerably inter- 
polated between the laterals. 

ORAL PAPILLAE 

The oral papillae (Figure 6, Table 7), of presumed sensory function, were counted 
because it was thought that they might be reduced in number in the relatively very small 
disc of L. lethophaga. These structures, which occur around the periphery of the disc 
among lampreys in general, are almost always distinguishable from the finbriae. They stem 
from the groove just ringing the slight pad from which the radially transverse fimbriae 
arise. They are conical and pointed, rather than being truncate with fimbriate edge. They 
are often irregularly spaced along each side, with a wide intervening separation posteriorly 
and with a narrow gap anteriorly, normally broken by a more or less precisely median- 
anterior papilla (rarely missing, doubled, or trebled). Slight uncertainty in counts arises 
from the rather rare apparent or real intergradation between papillae and fimbriae, at least 
in superficial aspect. In one specimen from Klamathon, irregularities, involving adven- 
titious creases and folds around the outer part of the disc, render the count useless. A fine 
jet of air aids in the count. 

In mean numbers and in the range of variation, the papillae are rather similar in L. 
lethophaga and L. tridentata (also in the specimen from Willow Creek of doubtful 



144 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



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HUBBS: A NEW NONPARASITIC LAMPREY 



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146 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

pertinence), though the counts for the nonparasitic form may be slightly the more variable 
and slightly the lower on the average, because of some low-count variants. 

MYOMERES 

The myomeres were counted, as recommended by Hubbs and Trautman (1937: 28), 
from the first segment that wholly (or almost wholly) lies behind the groove around the last 
gill-opening, to the one whose lower posterior angle lies in part or wholly above the cloacal 
slit. 

The number, for both ammocetes and adults, has proved to be highly variable in 
Lampetra lethophaga. with a suggestion of some regional diversity, though with a broad 
overlap. For the three stream systems the counts follow: 

Pit River (29 specimens): 63-69; mean 65.62±.31. 

Sprague River (8): 58-66; mean 63.50±.94. 

Crooked Creek (46): 63-73; mean 67.20±.29. 

Bond (1961: 14) gave the number for ammocetes, presumably from Crooked Creek, 
as about 65-70. Ting T. Kan (pers. comm., 1970) counted 63-69 (mean 65.71 ±.16) in 
95 ammocetes from Crooked Creek, in part overlapping the specimens 1 have counted. 

These numbers roughly approximate, in mean value, those found for Lampetra 
tridentata, in which, however, there is much regional variation in this character. On the 
basis of myomere counts Creaser and Hubbs (1922: 6) erroneously separated that species 
into two subspecies: " Entosphenus t. tridentatus" from Unalaska to the Columbia River, 
with 68 74, and "E. t. ciliatus," from southern Oregon to southern California, with 57 - 
67 myomeres. For a series from Coyote Creek in central California, however, Hubbs 
(1925: 592) gave the range as 67 - 76, and Hubbs (1967: 307) listed 60 - 70 for 5 specimens 
from southern California and from off northwestern Baja California. Other, unpublished, 
counts have mostly approximated 70. 

PROPORTIONAL MEASUREMENTS 

The proportional measurements (Table 8) of body parts (expressed as permillage of total 
length) are fairly consistent among the adults referred to L. lethophaga from the different 
stream systems, but are in part somewhat different from the values for the dwarf Klamath 
River stocks of L. tridentata. Outstandingly different is the size of the oral disc, which, as 
would be expected, is the smaller in the nonparasitic form (36-49 vs. 74-96); the Willow 
Creek form (of uncertain species) is strikingly intermediate (64). A similar relation, as to 
be expected, holds for the snout length, though with some overlap. Little difference is 
indicated for eye length of adults, except that the eye is largest in the Willow Creek 
specimen. Length over gill-pores seems to average only slightly lower in L. lethophaga than 
in the Klamath precocious stocks of L. tridentata: the value for the Willow Creek example is 
a bit higher than the average for the L. tridentata series. Virtually the same relation holds 
for body depth, again with much overlap. The tail, also with much overlap, averages longer 
in the L. lethophaga than in the L. tridentata series, but is distinctly longer in the Willow 
Creek specimen. 

Measurements of ammocetes and transformers as well as adults of L. lethophaga 
indicate some average ontogenetic changes in body proportions. Consistent differences 
with age and stage, however, are not clearly shown for the tail length. As is usual in 
lampreys, the body depth increases and the point of greatest depth shifts from near the last 
gill-slit to just before the origin of the dorsal fin. The distance over the gill-pore series is 
shorter in the transformers and in the adults than in the ammocetes. The eye, snout, and 
length over gill-pores appear to average proportionately larger in adults than in trans- 
formers. 



1971 



HUBBS: A NEW NONPARASITIC LAMPREY 



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148 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

In his key to the lampreys of Oregon, Bond (1961: 14) entered "body rather stout and 
deep" for L. le t hop haga {his "'Lampetra sp."), which would suggest a contrast with L. 
tridentata, though he included no alternative for the parasitic species. He had, I assume, 
adults of L. lethophaga only from Crooked Creek, where the mature specimens exhibit 
nuptial features, with the body often turgid, whereas in general L. lethophaga is much 
slenderer than the precocious populations of L. tridentata in the Klamath River system. 
Other contrasting characters assigned by Bond presumably reflect the nuptial 
modifications of L. lethophaga in Crooked Creek. 

COLOR 

Life colors were annotated in the field on maturing to mature adults, comprising the 
male and female type specimens (UMMZ 130648 and 130649) from Fall River (Location 
2), and on one maturing male (UMMZ 130576) from Sprague River opposite Ferguson 
Butte (Location 7); collected respectively on August 17 and August 10, 1934. Three types 
taken in vegetation displayed only a trace of the silvery color of macrophthalmiae. They 
were slaty above to bright brassy-silvery below. The fins were clear waxy-yellow. Of those 
taken under a stone, the males seemed to approach the silvery color typical of macroph- 
thalmiae more than did the females. The one male from Sprague River, taken in dense 
vegetation, was deep purplish-brown above the lighter belly, and showed no trace of the 
silvery phase. 

Preserved adults not in full nuptial condition, whether early in development or of 
stocks that do not attain typical nuptial characters, are dusky purplish over most of the 
surface, becoming pale yellowish on lower surfaces of head and trunk and on the ventral fin 
fold behind the anus; the mid-dorsal ridge is weakly lighter; and the second dorsal is dusky 
on the extreme base only. Specimens in full nuptial development are blackish-purple on the 
darker areas and on the basal part of both dorsal fins, and the region about the cloaca is 
conspicuously paler. 

The caudal fin in adults is variably darkened, but is generally darkest along the edges 
of the muscle mass and often lighter near the edge. In high-nuptial adults the caudal area 
becomes very deeply pigmented, and is almost black along a basal strip, especially on the 
lower side. 

Younger ammocetes are almost uniformly darkened, barely lighter below. The caudal 
fin is at first largely clear, except in the narrow dark streak margining the muscle mass, 
about equally above and below. With increasing size the caudal fins grow darker, 
progressively outward, as the lighter margin becomes narrow. At any stage, however, the 
paler border varies much in width and intensity, as does the basal dark streak. Occasion- 
ally, a submedian dark streak develops on either lobe, and the dark area may be blotched. 

Transformers are rather evenly pigmented, and the caudal area is largely dark, with 
the paler border and the dusky basal streaks varying much in width and intensity. Recently 
transformed specimens contrast sharply with those of L. tridentata, including the pre- 
cocious Klamath types, in color, in the same way that the macrophthalmiae of L.fluviatilis 
and L. planer i differ (Hardisty, Potter, and Sturge, 1970: 385, pi. 1). 

At all stages the pigment in the caudal fin area is often marked along the axial line by 
small dusky blotches, from which close-set and very oblique melanophore files extend 
across the muscle mass, above and below, margining the myomeres. 

All of the color features, and in the stated variation, as described above, were seen in 
both ammocete and adult stages of the parasitic stocks of the Klamath River system, and 
elsewhere. Therefore, I fail to confirm any pigmentary difl'erentiation that may be implied 
in the statements, in the key to Oregon lampreys by Bond (1961: 14), that the ammocetes 
of the nonparasitic form that he designated ""Lampetra sp." have "dark pigmentation 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 149 

outlining tip of tail," and that the larvae of L. tridentata have "a dark line above and below 
tip of tail." 

Vladykov (1950, 1960) described in detail sharp pigmentary differences at various 
ammocete stages between Lampetra lamottenii (Leseuer) and Petromyzon marinus, but J. 
R. Nursall and D. G. Buchwald (pers. comm., 1970) have found that Lampetra lamottenii 
in this respect agrees essentially with the closely related parasitic L.japonica. 

LIFE HISTORY TYPE 

An outstanding reason for the interpretation of Lampetra lethophaga as a distinct 
species of the Entosphenus complex is its alignment among the nonparasitic lampreys, 
which have traditionally been accorded specific rank. 

It is now recognized that nonparasitic forms have repeatedly evolved from parasitic 
lampreys. The original discovery, now well analyzed, was that of Lampetra fluviatilis 
(Linnaeus) and L. planeri (Bloch), and a parallel case involving Pacific forms of the 
subgenus Lampetra has been documented (Vladykov and FoUett, 1965). A few parasitic/ 
nonparasitic pairs were implicit in the revision of northern lampreys by Creaser and Hubbs 
(1922) and the repeated origin of nonparasitic forms from parasitic ones was definitely 
indicated by Hubbs (1925) for northern lampreys in general and by Hubbs and Trautman 
(1937) for three separate lines within the genus Ichthyomyzon, one of which had been 
treated earlier (Reighard and Cummins, 1916); the dual origin of nonparasitic forms from 
one parasitic species in this genus was indicated by Raney (1952). The speciational aspect 
of the repeated origin of nonparasitism in lampreys was mentioned by Hubbs (1940: 203; 
1941: 188 - 189). Other authors, in particular Zanandrea (1951 - 1962) treated and 
expanded on the problem of "paired species of lampreys." Alvarez del Villar (1966) 
discovered the nonparasitic Tetrapleurodon of Mexico, and Potter (1968, 1970; Potter, 
Lanzing, and Strahan, 1968; Potter and Strahan, 1968) described, as a full species, the 
nonparasitic form of the Southern Hemisphere genus Mordacia. Hardisty (1963, 1969) and 
others have also dealt with this problem. The systematic status and frequency of the 
"paired species" is being discussed by Hubbs and Potter (in press) and the biological 
interrelations are being treated by Hardisty, Potter, and Sturge (in press). 

Lampetra lethophaga parallels the other nonparasitic lampreys in the rapid maturing of 
the gonads, which attain full maturity soon after metamorphosis. No difficulty is 
experienced in sexing either transformers or early-stage adults. As usual in fishes the testis 
at comparable early stages can be distinguished from the ovary by the circumstance that it 
is a slenderer, thinner, whiter, and more opaque band. The testis of this lamprey was 
observed to become markedly lobular as it rapidly enlarges during metamorphosis. The 
penis at full maturity remains small (Figure 2A). In the holotype, the penis does not 
extrude. 

When Lampetra lethophaga was first encountered in August, 1934, and for a long 
time thereafter, no doubt was felt regarding its interpretation as a nonparasitic species, the 
first to be recognized in Entosphenus. The discovery of the Miller Lake lamprey, a 
reportedly even more dwarfed yet parasitic form of the same complex, however, has called 
for a more thorough appraisal of the evidence for the ehmination of feeding by the adults 
of L. lethophaga. 

Not one of the considerable series of adults of L. lethophaga, taken throughout much 
of the year (Table 1) and representing a full range of stages in maturity was found to 
contain any food in the gut. A few had the intestinal wall darkened by apparent 
hemorrhage and a few had lumps of some material in the gut, but these appeared to be 
cysts and indeed one when opened discharged a larval nematode. Nor did any of the 114 
transformers from Hat Creek (Location 3), collected on October 4, 1968, show signs of 



150 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

having eaten. 

Ammocetes longer than about 100 mm, taken May 3 16, June 26-27, August 13- 
17, September 4, and October 4 20, showed that early stages in the maturing of the 
gonads are represented through this long period (Table 1). Transformers, taken on 
September 4 (one specimen) and on October 4(114) show that the gonads undergo further 
maturing in that stage: the ova in many of these specimens, even before the elaboration and 
cornification of the teeth, were estimated, by visual inspection, to be from one-fourth to 
one-half full size, and to be far fewer than in the dwarfed parasitic form of the Klamath 
system. Bare traces were observed of the postmetamorphic macrophthalmia stage (charac- 
terized by much enlarged eyes and silvery color), such as is prominently shown by the 
parasitic populations of L. tridentata, both dwarfed and full-sized. The incipient macro- 
phthalmiae of L. lethophaga contrast with the typical macrophthalmiae of L. tridentata 
just as do the corresponding stages of L. fluviatilis and L. planeri, as well depicted by 
Hardisty, Potter, and Sturge (1970: 385, pi. 1). 

All adults taken from February 16 to August 17 (Table 1) have gonads in various 
stages from early to full maturity, though they are, with only moderate overlap, smaller 
than the transformers (Figure 8). The smaller size of the adults presumably resulted from 
the actual shrinkage that is known to occur in lampreys during transformation, with, in the 
case of nonparasitic forms, no later resumption of growth. However, the transformers and 
the adults did not come from the same place. 

Pertinent testimony was secured from the personnel of the Klamath State Fish 
Hatchery on Crooked Creek (Location 11), where several series of this lamprey were 
collected at various times of the year. On August 13, 1934, the superintendent of the 
hatchery informed me that considerable numbers of small lampreys about 5-8 inches long 
which are removed from the screens of the hatchery ponds each year about June contain 
eggs "about the size of whitefish eggs, showing through the belly along almost the entire 
length of the body." He added that there are definitely no "runs of eels" in this or in other, 
nearby streams. On February 5, 1945, the late Dr. Paul R. Needham reported (pers. 
comm.) that the superintendent had not seen any of the lampreys. On recent occasions the 
hatchery employees have provided Dr. Carl E. Bond (pers. comm., 1970) with corrobora- 
tive testimony. 

Fish management studies on lower Hat Creek (Location 3) have led Dr. Roger A. 
Barnhart (pers. comm., 1970) to conclude that the lamprey of that stream is a nonparasitic 
"brook'" form. Nor have I found any evidence of parasitic lampreys in the drainage basins 
of Pit, Sprague, or Sycan rivers, or in Crooked Creek, from which the material of 
Lampetra lethophaga was obtained. 

SEX RATIO 

By gross examination it was readily feasible to ascertain the sex ratio of ammocetes 
larger than 90 mm total length and of all transformers, as well as the adults. The sex of 
some ammocetes and a few of the transformers of earliest stage was not listed until a small 
piece of the gonad had been teased apart or crushed between slides, so as to distinguish the 
testicular tubules from early ova. For only two of the 1 15 transformers examined was any 
hesitation encountered in the sexing. 

For all 187 specimens sexed, of all stages, the females were moderately outnumbered 
by the males 87: 100. The ratio of females per 100 males seems to decrease with the stage of 
development: from 128 for 23 female and 18 male ammocetes longer than 90 mm, through 
79 for 51 female and 64 male transformers, to 72 for 13 female and 18 male adults. The 
significance of this indicated change in sex ratio, and indeed its validity, call for further 
study. Marked fluctuations have been indicated for the sex ratio of Lampetra planeri 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 151 

(Hardisty, 1944, 1954; Zanandrea, 1951). A preponderance of males has been found for 
Petromyzon (Applegate, 1950, App. E). 

ETYMOLOGY 

The name lethophaga, figuratively referring to the elimination of feeding as adult, is 
formed by combining the latinized expressions leth-, from the root of \-q9-q, a forgetting or 
forgetfulness; the normal connective -o- in words of Greek origin; phag-, from the root of 
<}>ay£iv, to eat; and -a, from the feminine of the adjectival suffix -os. 

RELATION OF NONPARASITIC LAMPETRA LETHOPHAGA 

TO DWARFED PRECOCIOUS PARASITIC FORMS 

REFERRED TO LAMPETRA TRIDENTATA 

Although Hardisty and Potter (in press) hold to the opinion that the genes do not 
interflow between the members of the respective parasitic/nonparasitic pairs, some 
indications have been emerging that within several of the "paired species" of lampreys the 
typical large parasitic form may to some degree intergrade with its dwarfed nonparasitic 
representative. Intermediacy in size is indeed shown by the "praecox" forms in several 
species, such as have been discussed by Berg (1931, 1948, 1962) and others. The reduction 
in size is thought to be due to a shortening of the parasitic cycle, which is also a sign of 
intermediacy. The high frequency of the "paired species" (Hubbs and Potter, in press) 
strongly suggests speciational plasticity, and begets the idea that nonparasitic populations 
may be polyphyletic even within any species complex. 

There have even been some suggestions that the nonparasitic types should be accorded 
only subspecific status. Thus, it has been proposed (Hubbs and Lagler, 1958: 36-37; 1964: 
36-37) that the American brook lamprey be distinguished only subspecifically as 
Entosphenus lamottenii lamottenii, since "in Alaska it appears to intergrade with the 
typical, often anadromous parasitic {ormjaponicus.'" This action, although drawing some 
support from studies by Heard (1966) and by J. R. Nursall and D. G. Buchwald (pers. 
comm.), was probably premature, but the problem of systematics within the Lethenteron 
group (now probably best treated, along with Entosphenus, as a subgenus of Lampetra), is 
definitely open. In some recent studies difficulty has been encountered in the identification 
of certain specimens of Ichthyomyzon, where /. bdellium (Jordan) and /. greeleyi Hubbs 
and Trautman are sympatric (Ernest A. Lachner, pers. comm., 1971). However, for the 
present at least, it seems advisable on both practical and theoretical grounds to maintain 
the nonparasitic forms at the full specific level. 

Suggestions that the parasitic and nonparasitic representatives may intergrade stem in 
considerable force from studies of the Entosphenus complex in the related drainage basins 
of the Pit and Klamath rivers, from which the nonparasitic form is herein being made 
known. Indeed, intermediacy between the two trophically contrasting types was probably 
first suggested (Hubbs, 1925: 589, fig. 16) for populations of "Entosphenus tridentatus" in 
these two river systems. A race of this species in Goose Lake of the Pit River system was 
shown as straddling the intervening line on the chart, on the basis of an examination of 
material in the United States National Museum collected by Barton Warren Evermann, 
and it was stated that: "Of a series of small adults, all taken on trout in this lake, the males 
showed a decided approach toward the brook type of lamprey in the close approximation 
of the dorsal fins, relatively blunt teeth, atrophy of the intestine and precocious sexual 
development. The females, oddly, were not so altered, but resembled the normal parasitic 
young of the species." It was added that "Some specimens from Klamath Lake, not far 
distant from Goose Lake, but in a distinct stream system, also show evidence of 
degeneration." I may have been dealing, however, merely with stocks in these lakes that 



152 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

were maturing at a small size, perhaps particularly as males, and were assuming the 
nuptial characteristics that may be essentially similar in the two trophic types. 

I have found other evidence of the existence in the Klamath River system of a 
presumably indigenous and landlocked local form (or of forms) intermediate in size 
between the large sea-run Lampetra tridentata and the endemic nonparasitic dwarf, L. 
lethophaga. Indeed, as is indicated below, there is reported to have been, in Miller Lake, an 
isolated parasitic form at least as small as L. lethophaga. 

Fifteen maturing adults only 214-274 mm long, no doubt at approximately the 
maximum size they would have attained, from Klamath River at Klamathon, have been 
studied. These specimens (SU 28783 and 35555) were collected at a fishery research 
installation, respectively by E. A. McGregor, in the fall of 1922, and by Charles H. Gilbert 
(who died in 1928). They are distinctive in the high number of cusps on the teeth. In this 
respect they resemble a series of 374 specimens in the macrophthalmia (early-transforma- 
tion) stage taken nearby, on February 24 to April 5, 1931, in Shasta River at its junction 
with the Klamath, in wiers set across the stream to tally downstream salmon migrants 
(Brown, 1938). Tooth and cusp counts taken on all specimens of both lots are herein 
tabulated, along with those o{ Lampetra lethophaga (Tables 3 - 6) as these lots are taken to 
represent or to approximate the ancestral form of L. tridentata from which the nonpara- 
sitic species originated. The counts for these two lots of L. tridentata are in fair agreement, 
with the unexplained exception that the Klamathon series yielded much the higher counts 
of bicuspid posterior circumoral teeth. This discrepancy seems particularly strange, when 
it is noted that the two series were taken only about 1 1 km apart. 

Stranger yet are the characters of a single specimen, even more deviant than those of 
the Klamathon series. It was taken from Copco Lake, only about 18 straight-line 
kilometers farther upstream, near the Oregon state line. This specimen, CAS 25987, 
collected by Millard H. Coots, was adhering to the tongue of a sucker, Catostomus 
rimiculus, that had been caught in a gill-net set overnight, June 3^, 1953. It is a subadult 
female, with the gut turgid with food and with the enlarging ova too few for the large sea- 
run type. It is 241 mm long, about as large as the Klamathon specimens, and its permillage 
measurements are included within the range for the Klamathon series in Table 8, but the 
dentition is sharply divergent: in particular, the total number of bicuspid posterior 
circumorals (16) is higher than in any of the 452 other specimens of L. tridentata tallied 
(Table 6), and some other counts are aberrant. The dentition of this specimen is as follows: 
longitudinal lingual cusps 29-29 = 58 (high); anterior lingual cusps 12 + 1 + 13 = 26 
(high); supraoral cusps 3 (normal); infraoral cusps 6 (aberrantly high); anterior circum- 
orals 5 (usual); lateral circumorals 2-3-3-2 — 2-3-3-2 (normal); posterior cir- 
cumorals 19 (very high) with 16 bicuspid (absolutely extreme) and only 3 unicuspid (next 
to lowest number; the seventh, tenth, and eleventh of the 19 teeth beginning with the 
anteriormost and foremost on the right side); 2 marginals on each side greatly dilated; total 
marginals 57; total teeth 104 (high); total cusps 220 (exceptionally high). Oral papillae 12 
+ 1+9 = 22 (high). 

The differences between the lampreys comprising the Shasta River, Klamathon, and 
Copco Lake series exemplify the tendency toward high local variability of resident 
lampreys, on a mosaic pattern. Small wonder that Lampetra lethophaga displays some 
local differences. 

Additional material of the "praecox" type of L. tridentata from the Klamath River 
and other systems, particularly from Goose and Klamath lakes, are currently under study 
by Dr. Carl E. Bond of Oregon State College and his graduate student Ting T. Kan. More 
or less comparable precociously spawning forms now referable to L. tridentata have come to 
my attention from southern California (Hubbs, 1967) and northward to Vancouver Island, 



\ 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 153 

British Columbia. Dwarf, nonmigratory races have been discussed by McPhail and 
Lindsey (1970: 58 59). There appear to be numerous forms that seem to be comparable to 
the races of salmon of diverse and distinctive size at maturity (in each case just before 
reproduction and death). 

Limited material at hand from the drainage basins of Clear Lake and of Lost River, in 
the Klamath system, may bear on the problem of possible intergradation of parasitic and 
nonparasitic representatives of the Entosphenus group. This is particularly true of a single 
specimen, a postnuptial male only 176 mm in total length (SIO 65 144) that was collected 
by William Johnson and Edward J. O'Neill on May 13, 1965 in Willow Creek, tributary to 
Clear Lake, Modoc County, California. Originally, as shown on the one-degree 1:250,000 
U.S.G.S. Modoc Lava-Bed Sheet of 1892, and on the accompanying distribution map 
(Figure 3), Willow Creek was the upper, southern headwater of Lost River, of the Klamath 
River upstream complex, but with an intermittent, presumably flood inflow into Clear 
Lake. Currently, the flow is directed into this lake, which thus has been enlarged as a 
reservoir. This specimen was first regarded as referable to Lampetra lethophaga, then was 
thought to represent, more likely, a greatly dwarfed parasitic race. A third possibility, 
suggested by some recent testimony, is that the specimen in question is merely an 
exceptionally dwarfed example of a moderately dwarfed resident population. Mr. O'Neill 
has informed me (pers. comm., 1971) that a number of lampreys 10-12 inches long have 
been taken adhering to crappies {Pomoxis sp.) in Willow Creek, and that many of the 
''rough fish" of this stream have shown lamprey scars. 

Neither by tooth and cusp counts (entered on Tables 3-6 in the row labelled "^L. sp."), 
nor by other characters, have I found it feasible to decide to which of these possibilities this 
Willow Creek fish can be assigned. In general, such postnuptial specimens are often 
difficult to refer to trophic type. On comparison with L. lethophaga and the precocious 
Klamath forms of Z.. tridentata this particular specimen is conspicuously intermediate in 
several respects, as follows: 

The Willow Creek specimen (Figures 2 C, D) is definitely smaller than any known 
mature parasitic adult from the Klamath River system, or elsewhere (other than the 
representatives mentioned below of the tiny parasitic form of Miller Lake, a disjunct part 
of the Klamath basin); yet is 16 mm longer than the largest transformed adult at hand of L. 
lethophaga (Figure 8). It is 23 mm shorter than the largest specimen in transformation, but 
lampreys shrink considerably during and just after metamorphosis. 

Particularly notable for the trophic indication is the measurement of the buccal disc 
(Table 8), which is intermediate, without overlap: 64 thousandths of the total length, vs. 36 
- 58 (mean 47) for L. lethophaga and 74 96 (81) for the L. tridentata series. The 
correlated snout length is also definitely intermediate, but with slight overlap. Body depth 
is probably also intermediate, but tail length and eye length are higher than in either type 
under comparison, and length over gill-pores is likely also high (Table 8). 

The regular formulae for the cusps on the two oral teeth (supraoral 3 and infraoral 5) 
and for the four lateral circumorals of either side (23-3-2) tend to align the Willow 
Creek specimen with the parasitic type (Tables 3, 4). Furthermore, the teeth are rather less 
degenerate than in breeding examples of L. lethophaga, and the median cusp on the 
supraoral is relatively large and sharp, instead of being reduced or absent as it usually is in 
the nonparasitic form. The total count of posterior circumoral teeth, however, seems 
intermediate: 2 higher than any count for L. lethophaga and on the low side for the 
parasitic lampreys from Klamath River (Table 6). 

The general appearance of the Willow Creek specimen approximates that of the 
mature adults of Z.. lethophaga from Crooked Creek, so much so as to suggest consanguinity: 
in each the color is dark, the entire face is strongly turgid, the whole form is robust, the 



154 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

dorsal fins are much expanded and in contact, and their edges are minutely frayed. 
However, the similarities may largely reflect a similar stage in sexual development. 

In conclusion, it does not seem justified to align the Willow Creek specimen with 
either L. lethophaga or with the Klamath River precocious populations of L. tridentata. Its 
general intermediacy, along with some extreme features, indicate it to be a representative 
of a somewhat distinct local form. 

Data possibly bearing on the uncertain status of the Willow Creek lamprey are 
furnished by two specimens taken on June 24, 1965 by Edward J. O'Neill and James Keith 
on the Clear Lake National Wildlife Refuge, during banding of White Pelicans. They were 
among 44 lampreys spewed up by one young pelican. These may have been captured by the 
parent(s) in Clear Lake (now used as a reservoir and a refuge), but may have come from 
elsewhere, as White Pelicans sometimes forage many miles from their rookery. Whatever 
their source, these 2 specimens, although very considerably damaged, seem to represent a 
stock different from that of the one Willow Creek specimen. They are larger: one not 
sexable measures about 220 mm in total length and the other, a female with nearly ripe 
ova, about 240 mm, vs. 176 mm. Permillage proportions, though hardly precise, seem to 
diff'er: tail length, 317 and 327 vs. 340; eye length 15 and 17 vs. 24; snout length 73 and 86 
vs. 93. Teeth and cusps number: transverse lingual cusps, 12+1 + 12 and 12+1 + 14 
(higher than in L. lethophaga); cusps on supraoral 3 and on infraoral 5 in each, as usual; 
posterior circumorals 16, apparently all unicuspid. Clearly these two specimens seem to 
represent a dwarfed population of parasitic lamprey, probably similar to the precocious type 
sampled from the Klamath River near Klamathon and perhaps similar to the form or 
forms occurring in Shasta River and the Klamath lakes. 

The most surprising circumstance bearing on the relationship between Lampetra 
lethophaga and the parasitic forms referred to L. tridentata is the discovery by Dr. Carl E. 
Bond of a parasitic form indicated as even smaller than L. lethophaga. This form seems to 
have been endemic in the small drainage basin (shown on the distribution map. Figure 3) of 
Miller Lake (named Fish Lake on some old maps), which basin is a disjunct, endorheic 
unit, ending in a marsh, at the north end of the Klamath drainage system. Dr. Bond has 
stated (pers. comm., 1971) that: 

The evidence for predation in the Miller Lake lamprey is strong. The little beasts prevented the 
maintenance of a trout fishery in the lake. They would kill trout and tui chub [Gila bicolor] and then mine 
out the soft parts, leaving the perforated skin and the skeleton on the bottom. Spawned-out lampreys were 
also devoured — even on the spawning beds. Miller Lake is in T 27 S, R 6 V2 E, Sections 11-14 and in a 
distrupted portion of the Klamath River drainage. 

The lamprey is now extinct, a[tragic]victim of a toxaphene operation designed by the Oregon State 
Commission to eradicate it. I had hoped that it had survived in the outlet. Miller Creek, but no specimens 
were taken there through extensive and thorough electrofishing by Harry Lorz of the Oregon State Game 
Commission in 1970, many years after the extinction of the lamprey. 

Adults from the spawning beds range from 72 to 129 mm, mostly between 80 and 105 mm. Many of the 
near-term ammocetes and some of the non-spawning adults are longer than the spawning adults. Some of 
the lampreys spawned in the very cold creeks that are tributary to Miller Lake, but the major spawning 
areas were along the lake shore. 

I have thought much during the past 15 years about the significance of the Miller Lake lamprey as a 
transitional form in a progression to nonparasitic habits. The creatures were locked into a 
system with only the tui chub, if indeed the chub was not planted later, and had adapted to the paucity of 
food by cutting a year or two off their lives, so that they metamorphosed in the fall and spawned in the 
spring and summer — feeding fiercely if food were available, but not growing beyond the length of the 
ammocoetes. Even when the Game Commission planted trout yearly the lampreys did not grow beyond the 
range I mentioned - although the trout plants were wiped out each winter. 

To me, the outstanding attribute of this form is that parasitism was not obligatory and that the 
population finally consisted of the offspring of ancestors that could feed fiercely if prey were on hand, but 
apparently could mature and spawn on a starvation diet. I suspect that if any native fish other than the 
lampreys were in Miller Lake, the populations were kept low by the lampreys — much as in the same 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 155 

manner that hatchery plants of trout were virtually wiped out. One year class could feast to the extent that 
the next would have little or nothing to eat, unless the Game Commission planted more trout. 

The alternative name of Fish Lake, found on various old maps, suggests that the tui 
chub was probably a native associate of the Miller Lake lamprey. 

A detailed comparison of L. lethophaga with this parasitic midget awaits the 
completion of the study by Dr. Bond and Mr. Kan. 

Clearly these data on the small lampreys of the Klamath River system are pertinent 
not only to their systematic appraisal, but also to the general problem of the relationships 
between parasitic forms of lampreys and their nonparasitic relatives, probable derivative. 
It is certainly conceivable that the two types do in some way intergrade, with or without 
active exchange of genes, and the strong possibility remains that some or even all of the 
nonparasitic types may be polyphyletic. 

GROWTH 

Data are inadequate to indicate clearly the life span of the ammocetes of Lampetra 
lethophaga but it appears probable that the period is at least four years (Figure 8) — 
comparable to the evidence for other lampreys (Loman, 1912; Meek, 1916; Okkelberg, 
1921, 1922; Hubbs, 1925; Schultz, 1930; Ivanova-Berg, 1931; Leach, 1940; Knowles, 1941; 
Hardisty, 1944- 1969; Churchill, 1947; Applegate, 1950; Horn and Bailey, 1952; Dendy 
and Scott, 1953;Seversmith, 1953;Zanandrea, 1951, 1954b; Hardisty and Potter, in press). In 
addition, I have unpublished, original, confirmatory observations for Petromyzon marinus 
Linnaeus, Okkelbergia aepyptera (Kirtland), Lampetra tridentata, and L. lamottenii. The 
graph for L. lethophaga (Figure 8) covers all localities and all dates, but most ammocetes 
measured were collected in August (40) and October (95); only 17 others were taken over 
the time span of May 3 to September 4. The sharp mode at 20 - 29 mm length presumably 
represents young-of-the-year, all of which were collected on August 13 (Table 1). The four 
modal size classes in the total-length range of 90 129 mm obviously represent at least one 
older year-class. The intervening size classes likely represent another. On the basis of life- 
history studies of other lampreys, it is highly probable that the 7 ammocetes longer than 1 59 
mm, all taken on October 20, would have undergone another year of larval life. 

The time of metamorphosis from the ammocete stage is adequately indicated only for 
the large collection of 114 individuals in early to late stage of transformation taken on 
October 4, 1968, by poison in Hat Creek near its mouth into Pit River, at Location 3. The 
only other transformer examined was the specimen taken on September 4, 1898 in the 
North (or South) Fork of Pit River, at Location 1 (Table 1). 

Entosphenus tridentatus, as well as other lampreys, probably also metamorphoses in 
the fall. Along with a large sample of ammocetes of that species taken in Trinity River at 
Lewiston, California, on November 8, 1945, are 2 males and 2 females in a late stage of 
transformation, but with the teeth remaining in pads or only partly and variably exposed. 
These transformers are 102, 106, 108, and 1 15 mm long, within the dominant size classes of 
the macrophthalmiae taken either at the same place, or in the lower Shasta River (Figure 
8). 

The size frequencies of the transformers of Z,. lethophaga form a normal curve (Figure 
8), which lies almost entirely higher than the sizes of either the transformed and 
transforming examples, just cited, or the precocious Klamath River type of/,, tridentata. 
An incompletely transformed specimen from Coyote Creek, at San Jose, California, was 
listed as of intermediate size, 141 mm, by Hubbs (1925: 594). It has been shown that 
nonparasitic lampreys metamorphose at a larger size than do their larger, parasitic 
relatives. This relation has been so stated for the paired species of Mordacia (Potter, 1970: 
497) and is being indicated as a generalization by Hubbs and Potter (in press) and by 



156 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 8. Total-length measurements of all material studied of the nonparasitic Lampelra lethophaga. of the 
specimen (L. sp.) of doubtful pertinence from Willow Creek, and of the parasitic, but praecox, form of L. 
iridentala. from Klamath River. The measurements were made to the nearest mm, but are grouped by cm (10-19, 
20-29, etc.). Number of specimens shown on ordinate. 

Hardisty and Potter (in press). 

In concordance with other evidence of size shrinkage during metamorphosis in 
lampreys, perhaps particularly in nonparasitic species, the modal size of the transformers 
seems lower than the size of the largest ammocetes, which are the only ones that could be 
expected to metamorphose. However, the ammocetes and the transformers were not taken 
at the same locality. 

It is probably also significant, and in line with expectation for a nonparasitic lamprey, 
that the postmetamorphic, maturing and mature adults of L. lethophaga are, with little 
overlap, smaller than the transformers of the same species, but are, to a comparable extent, 
larger than the recently transformed macrophthalmiae of the lower Shasta Creek 
population of the parasitic L. tridentata (Figure 8). It has been observed for several 
lampreys that growth during transformation is negative. 

It appears (Table 1 ) either that the time of breeding is unusually variable in Lampetra 
lethophaga. or that full sexual development may be long delayed. Specimens taken in 



y 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 157 

Crooked Creek (Location 1 1) and in a spring near Sprague River (Location 10), the only 
ones exhibiting definite nuptial modification, obviously had spawned, or would have 
spawned, in late winter or spring, for they were collected from February 16 to April 6 
(Table 1). The other adults, at least some seemingly neotenic (see next section), were 
collected over the summer, from June 2 to August 17. The 1 1 adult types, taken on August 
17 at Location 2, exhibited a wide variation in maturation, thus suggesting prolonged 
spawning unusually late in the year, or possibly a partial or even complete suspension of 
sexual development over the next winter. The single adults taken at five locations from 
June 2 to August 10 also varied widely in degree of maturation, further suggesting 
prolonged sqawning over the summer. 

The great difference between the growth patterns of two resident types in the Pit- 
Klamath area is that L. lethophaga almost surely does not grow as adult, whereas the 
presumably resident, dwarfed forms of L. tridentata appear to double their size during 
their adult, parasitic life — even though they reach only about half the length attained by 
the larger sea-run populations of L. tridentata. 

NEOTENY 

Lampetra lethophaga exhibits, apparently in some populations only, definite in- 
dications of what may be considered as neoteny, other than that of merely reproducing 
soon after the postammocete metamorphosis. 

The only specific reports of neoteny in a lamprey that I have found are by Zanandrea 
(1956, 1957a, 1958a, 1961) for the nonparasitic Lampetra zanandreai Vladykov. (This 
species is regarded by Hubbs and Potter (in press) as an isolated member, confined to the 
Po River drainage of Italy, of the subgenus Lethenteron, which has hitherto been regarded 
as restricted to the Arctic Ocean drainage from Europe to North America, to the North 
Pacific tributaries of Asia, and to northeastern North America.) Zanandrea (1961: 530) 
found at one locality 12 female ammocetes in an advanced ("third") stage of ovarian 
development, one of which "showed well-developed principal secondary sexual characters, 
namely, enlargement of the two dorsal fins, development of the anal pseudo-fin, and the 
transparent appearance of the body wall, through which the eggs can be seen . . . characters 
. . . normally associated only with adults that are about to spawn." He obtained at another 
locality other neotenic female ammocetes, constituting about one-fifth of a series of 221 in 
the larval stage. He suspected that neoteny in each place may have been induced by tannery 
pollution, but a test performed to check this suspicion was inconclusive. 

The type of neoteny attributed to L. lethophaga involves the maturing at some 
locations of apparently all individuals of both sexes in the prenuptial condition. This is 
most strikingly shown by the adults from Fall River (the type station, at Location 2). They 
had passed through the ordinary, prejuvenile metamorphosis (transformation), but al- 
though some are in full maturity (witness a female turgid with large ova — Figure ID), 
none has developed the ordinary nuptial attributes: melanistic pigmentation and the 
"principal secondary sexual characters" outlined above in the quotation from Zanandrea. 
These attributes are seen, well-developed, in 13 adults from Crooked Creek (Figure 2 A, B), 
in two males from the Sprague River system (Locality 10), in the specimen of uncertain 
species from Willow Creek (Figure 2 C, D), and in the 15 specimens, in early to late stages 
of maturing, of the dwarfed parasitic form (referred to L. tridentata) from Klamath River 
at Klamathon. These are the normal attributes of the nuptial stage of lampreys in general, 
attained at what may be called the second or nuptial metamorphosis. That transformation 
seems to have been elided at the head of Fall River (type locality of L. lethophaga), and is 
not evident in other specimens from the Pit River system. Series from the Klamath River 
complex other than at Locations 10 and 1 1 seem to be developing like the Fall River lot 



158 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

(maturity in prenuptial appearance). Therefore, the retention or ehmination of the normal 
nuptial metamorphosis does not appear to provide a sound basis for the systematic 
distinction of nonparasitic lampreys of the Klamath complex from the Pit River form 
(typical L. lethophaga). 

The stocks that are neotenic in the sense of developing without the usual nuptial 
attributes retain to a very large degree, through maturity, the features displayed in the late 
stages of the ordinary, prejuvenile metamorphosis. The body remains trim and non-turgid, 
and pale; the dorsal fins remain well separated, with at most a slight connecting ridge, and 
stay thin and non-turgid, low, and unfrilled at the margin; the other fins stay rather similar; 
even the anal is generally little enlarged, though moderately enlarged and turgid in the 
female shown in Figure ID; the cloacal margins are little swollen; and the preanal fin fold 
is scarcely enlarged. 

The neoteny was notably evident at the type locality (Location 2), where the water was 
cold (summer readings of 11.4-13.3° C), but the low temperature was presumably not a 
factor suppressing nuptial development because in Crooked Creek (Location 11), where 
the nuptial characters are well developed, the water was even colder (7.8° C in August). 

REGIONAL DIVERSITY 

There is considerable evidence of local diversity in Lampetra lethophaga other than 
the retention or loss of the nuptial metamorphosis, just discussed, but this observed 
diversity does not seem to warrant specific or subspecific distinction between the popu- 
lations of the two main stream systems, or between populations within either system. In the 
analysis of variation the Crooked Creek population is contrasted with the populations 
sampled from the Sprague (including the Sycan) River system, both in the Klamath 
complex. 

There seems to be some regional difference in the frequency of cusp number on the 
oral plates (Table 3). Loss of the median supraoral cusp is less frequent in Fall River 
specimens (the only fully adult ones from the Pit River system) than in those from Crooked 
Creek, but the few examples from the Sprague River system are intermediate. Some 
increase in number of infraoral cusps beyond the Entophenus standard of 5 was found in 
material from Crooked Creek and the Sprague River system, but not in the Fall River 
specimens. 

There appear to be differences between the samples from the three stream systems in 
the frequency of reduction in cusp number on the four lateral circumorals from the typical 
Entosphenus pattern of 2-3-3-2 (Table 4). The frequency of bicuspid posterior 
circumorals runs higher in the Pit River sample than in the Crooked Creek specimens, 
whether tallied by individual teeth numbered from the side (Table 5) or by total number 
(Table 6), and again the specimens from the Sprague River system seem intermediate. 

There may be average differences in number of trunk myomeres: lowest in the 
Sprague River system, highest in Crooked Creek, intermediate in the Pit River system. 

There are some indicated average differences in proportional measurements (Table 8). 
In the larger ammocetes tail length and length over the gill-pores average longest for the 
Sprague River specimens, but only 2 are available. Very slight differences among the 
adults may be related to the expression of nuptial features in 2 of the 5 adults from the 
Sprague River system and in all 13 adults from Crooked Creek. 

The more or less definite indications of local diversity in Lampetra lethophaga are 
consistent with the differentiation, seemingly mosaically arranged, that has been observed 
among lampreys in general, and among the nonparasitic forms in particular (Hubbs, 1925: 
590). Some citations for the genus Lampetra are as follows: For subgenus Entosphenus — 
Creaser and Hubbs, 1922: 6, 10-11; Hubbs, 1925: 589; 1967. For subgenus Lethenteron 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 159 

— Creaser and Hubbs, 1922: 12; Jordan and Hubbs, 1925: 98-99; Hubbs, 1925: 589; 
Berg, 1931: 92-93, 98-105; 1948: 35-42; 1962: 29-37; Hubbs and Lagler, 1958 and 
1964: 36; Heard, 1966; Hubbs and Potter, in press. For subgenus Lampetra — Creaser and 
Hubbs, 1922: 13; Hubbs, 1925: 590. For all three subgenera Hardisty, 1963: 20. 

From a partial survey of the literature and from some original material I strongly 
suspect (see Hubbs and Potter, in press) that some of the rather confusing treatment of the 
local forms of Eudontomyzon reflect strong local diversity more complex than the simple 
alignment of the forms into two paired species, the parasitic E. danfordi Regan and the 
nonparasitic E. vladykovi (Zanandrea), plus the reputedly unpaired nonparasitic E. mariae 
(Berg). 

A more detailed and more critical analysis and interpretation of the seemingly 
heterogeneous local populations of lampreys seems to be definitely in order. 

ACKNOWLEDGMENTS 

Many have contributed ideas, notes, specimens, and other assistance for this report. 
Particular acknowledgment is offered to those named alphabetically below, and to the 
National Science Foundation, which has generously supported my continuing researches on 
fishes, currently by grant GB 13319. Dr. Roger A. Barnhart, Leader of the California 
Cooperative Fishery Unit at Humboldt State College (Areata, California) sent on loan and 
gift the large collection of transforming specimens that he collected and preserved during 
fish-management operations on Hat Creek (Location 3); and he provided information on 
this collection. Particular acknowledgment is due Dr. Carl E. Bond, along with his 
graduate student Ting T. Kan, for extensive field and laboratory data on collections of L. 
lethophaga from Crooked Creek (Location 11). They have patiently foregone describing 
and naming the subject of this paper, and they have also provided information on the 
remarkably dwarfed parasitic lamprey of Miller Lake, Oregon. Dr. Alexander J. Calhoun, 
Chief of the Inland Fisheries Branch of the California Department of Fish and Game, 
provided needed information on collecting localities and on available material, notably the 
large series of transforming brook lampreys from Hat Creek. Through kindly cooperation 
and assistance. Dr. William N. Eschmeyer, W. L Follett, Lillian Dempster, and staff' of the 
Division of Ichthyology of the California Academy of Sciences, significantly augmented 
the material for this study. In 1934, Mr. W. I. Howland, then superintendent of the 
Klamath State Fish Hatchery on Crooked Creek, Oregon provided significant information 
on lamprey runs locally and in the surrounding area. Laura C. Hubbs participated in the 
collection of the types and other specimens and has extensively assisted in the entire 
research, not only during the preparation of this report but also during intermittent studies 
of lampreys for half a century. Dr. Tamotsu Iwai, of the Department of Fisheries, Kyoto 
University, provided information on the distribution o{ Lampetra tridentata in Japan. Dr. 
Elizabeth M. Kampa painstakingly drew the dentition of Lampetra tridentata (Figure 7). 
Dr. Robert Rush Miller of the Museum of Zoology, University of Michigan, collected 
specimens for this study, annotated the habitats sampled, loaned much material for this 
and related studies, and provided pertinent field data. The late Dr. James W. Moffett, then 
in charge of the United States Fish and Wildlife Service laboratory at Stanford University, 
was largely responsible for the securing of large numbers of fyke-net collections of the 
dwarfed parasitic stocks o{ Lampetra tridentata from the Klamath River system. Others 
who cooperated in securing specimens of this species from northern California were the 
late Dr. Paul R. Needham, Dr. Leo Shapovalov, Dr. Stanford H. Smith, and the late Dr. 
A. C. Taft. Mr. Edward J. O'Neill, Biologist of the Tule Lake National Wildlife Refuge, 
sent me, at the suggestion of Mr. William Johnson of the U.S. Public Health Service, the 
fine postnuptial specimen from Willow Creek, tributary to Clear Lake, that is notable as 



160 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

being intermediate in some respects between L. lethophaga and the dwarfed parasitic L. 
tridentata of the Klamath River system. Mr. CNeill also provided dwarfed parasitic 
specimens from a White Pelican nest on Clear Lake. Dr. Ian C. Potter, of Bath University 
of Technology, in England, coauthor with me of the revision in press of the lampreys of the 
world, contributed many ideas and references that have been utilized in the present 
research. Mr. Howard G. Shirley has been patient and skillful in the final drafting of the 
distribution maps (Figures 3 and 5) and the graph of length measurements (Figure 8). The 
late Dr. Albert Hazen Wright of Cornell University, with the cooperation of Dr. Edward 
C. Raney, made available two fine adult specimens that he collected, along with 
information on the peculiar habitat. 

This paper is a contribution from Scripps Institution of Oceanography, University of 
California, San Diego. 

LITERATURE CITED 

Alvarez del Villar, Jose 

1966. not "1964" . Ictiologfa michoacana, IV; Contribucion al conocimiento biologico y sistematico de las 
lampreasde Jocona, Mich. Anal. Escuela Nac. Ciencias Biol., 13; 107 144, figs. 1-10. 

Aoyagi, Hyoji 

1957. General notes on the freshwater fishes of the Japanese Archipelago. Daishukan Shoten, Tokyo: 1-272 

+ 22. 

Applegate, Vernon C. 

1950. Natural history of the sea lamprey ( Petromyzon marinus) in Michigan. U.S. Fish and Wild. Serv.: 
Spec. Sci. Rept.; Fish., 55: i-xii, 1-237, frontisp., figs. 1 65. 

Bailey, Reeve M., and Carl E. Bond 

1963. Four new species of freshwater sculpins, genus Cottus. from western North America. Occ. Pap. Mus. 
Zool. Univ. Michigan, 634: 1-27, figs. 1^. 

Behnke, Robert J. 

1970. The application of cytogenetic and biochemical systematics to phylogenetic problems in the family 
Salmonidae. Trans. Amer. Fish. Soc, 99 (1): 237-248. 

Berg, L. S. 

1931. A review of the lampreys of the northern hemisphere. Ann. Mus. Zool. Acad. Sci. URSS, 32: 87-1 16, 

pis. 1 8. 
1948. Ryby presnykh vod SSSR i sopredefnykh stran. Faune SSSR. Akad. Nauk SSSR, 27, 4th ed., vol. 1: 

1^66, figs. 1-281. (Translated, 1962.) 
1962. Freshwater fishes of the U.S. S.R. and adjacent countries, vol. 1; 1-504 (= 1-465 of 4th ed., 1948 + 2-p. 

addenda to 4th ed. +1317-1325 from vol. 3 of 4th ed.), figs. 1-281. (Translation of 1948 ed.) 

Bond, Carl E. 

1961 . Keys to Oregon freshwater fishes. Agric. Exp. Sta. Oregon Sta. Univ., Corvallis, Tech. Bull. 58: 1^2, 
figs. 1 10. 

Brown, Merrill W. 

1938. The salmon migration in the Shasta River (1930 1934). California Fish and Game, 24(1): 60-65, figs. 

17-22. 

Churchill, Warren S. 

1947. The brook lamprey in the Brule River. Trans. Wisconsin Acad. Sci., Arts and Letters, 37, for 1945: 
337-346, charts 1-2. 

Creaser, Charles W., and Carl L. Hubbs 

1922. A revision of the Holarctic lampreys. Occ. Pap. Mus. Zool. Univ. Michigan, 120: 1 14, pi. 1. 

Dendy, Jack S., and Donald C. Scott 

1953. Distribution, life history, and morphological variations of the southern brook lamprey, Ichthyomyzon 
gagei. Copeia, 1953 (3): 152 162, figs. 1-2, pi. 1. 

Evermann, Barton Warren, and Seth Eugene Meek 

1898. A report upon salmon investigations in the Columbia River basin and elsewhere on the Pacific Coast 
in 1 896. Bull. U.S. Fish Comm., 1 7 (2): 1 5-84, figs. 1 6, pis. 1 2. 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 161 

Gilbert, Charles H. 

1898. The fishes of the Klamath River basin. Bull. U.S. Fish Comm., 17 (1); 1-13, 6 figs. 
Hardisty. M. W. 

1944. The life history and growth of the brook lamprey (Lampetra planerij. J. Anim. Ecol., 13 (2): 1 10-122, 
figs. 1-6. 

1951. Duration of the larval stage in the brook lamprey (Lampetra planeri). Nature, 167: 38-39, 1 fig. 
1954. Sc\ TdUo in spawning populdlions of Lampetra planeri. Nature, 173:874-875. 

1961. The growth of larval lampreys. J. Anim. Ecol., 30: 357-371, figs. 1-5. 
1963. Fecundity and speciation in lampreys. Evolution, 17(1): 17-22. 

1969. A comparison of gonadal development in the ammocoetes of the landlocked and anadromous forms of 
the sea lamprey Petromyzonmarinus. J. Fish Biol., 1 (2): 153 166, figs. 1-5. 

Hardisty, M. W.. and I. C. Potter 

In press. The behaviour, ecology and growth of larval lampreys. In The biology of lampreys, ed. by M. W. 
Hardisty and I. C. Potter. Academic Press, London. 
Hardisty, M. W., I. C. Potter, and R. Sturge 

1970. A comparison of the metamorphosing and macrophthalmia stages of the lampreys Lampetra 
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Hubbs, Carl L., and Karl F. Lagler 

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Hubbs, Carl L., and Robert R. Miller 

1948. II. The zoological evidence/Correlation between fish distribution and hydrographic history in the 
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Hubbs, Carl L., and Milton B. Trautman 

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1900. The fishes of North and Middle America. Bull. U.S. Nat. Mus., 47, pt. 4: i-ci, 3137-3313, pis. 1-392. 

Jordan, David Starr, and Charles Henry Gilbert 

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figs., pis. 42-85. 



162 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Jordan, David Starr, and Carl Leavitt Hubbs 

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Knowles, F. G. W. 

1941. The duration of larval life in ammocoetes and an attempt to accelerate metamorphosis by injections of 
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Leach, W. James 

1940. Occurrence and life history of the northern brook lamprey, Ichthyomyzon fossor. in Indiana. Copeia, 
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Lindberg, G. U., and M. I. Legeza 

1959. Ryby Yaponshogo morya i sopredel'nykh chastei Okhotskogo i Zheltogo morei. Part 1. Amphioxi 
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McPhail, J. D., and C. C. Lindsey 

1970. Freshwater fishes of northwestern Canada and Alaska. Fish. Res. Bd. Canada Bull. 173: 1-381, illus. 

Meek, Alexander 

1916. The migrations of fishes. Edward Arnold, London: 1^27, frontisp., figs. 1 128. 

Nemoto, Takahisa 

1955. White scars on whales / (I) Lamprey marks. Sci. Repts. Whales Res. Inst., no. 10: 69-77, figs. 1-10. 

Okada, Yaichiro, and Hyozi Ikeda 

1938. Contribution to the study of the freshwater fish fauna of Hokkaido, Japan. Sci. Repts. Tokyo Bunrika 
Daigaku (Sect. B), no. 55: 133-162, figs. 1-6. 

Okkelberg, Peter 

1921. The early history of the germ cells in the brook lamprey Entosphenus appendix (Gage) up to and 
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1922. Notes on the life history of the brook lamprey, Ichthyomyzon unicolor. Occ. Pap. Mus. Zool. Univ. 
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Potter, I.e. 

1968. Mordacia praecox, n. sp., a nonparasitic lamprey (Petromyzonidae), from New South Wales. Proc. 
Linn. Soc. New South Wales, 92 (3): 254-261 , figs. 1 -3, pi. 14. 

1970. The life cycles and ecology of Australian lampreys of the genus Mordacia. J. Zool., London, 161 (4): 
487-51 1, figs. 1-10, pi. 1. ' 

Potter, I. C, W. J. R. Lanzing, and R. Strahan 

1968. Morphometric and meristic studies on populations of Australian lampreys of the genus Mordacia. J. 
Linn. Soc. (Zool.), 47 (3 1 3): 533-546, figs. 1 ^, pi. 1 . 

Potter, I. C, and R. Strahan 

1968. The taxonomy of the lampreys Geotria and Mordacia and their distribution in Australia. Proc. Linn. 
Soc. London, 179 (2): 229-240, pis. 1-2. 

Raney, Edward C. 

1952. A new lamprey, Ichthyomyzon hubbsi, from the upper Tennessee river system. Copeia, 1952 (2): 
95-99, pi. 1. 

Reighard, Jacob, and Harold Cummins 

1916. Description of a new species of lamprey of the genus Ichthyomyzon. Occ. Pap. Mus. Zool. Univ. 
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Rutter, Cloudsley 

1 908. The fishes of the Sacramento San Joaquin basin, with a study of their distribution and variation. Bull. 
U.S. Bur. Fish., 27: 103-152, figs. 1-4, pi. 6. 

Schultz, Leonard P. 

1930. The life history o^ Lampetra planeri Bloch, with a statistical analysis of the rate of growth of the larva 
from western Washington. Occ. Pap. Mus. Zool. Univ. Michigan, 221: 1 35, figs. 1 10, pis. 12. 



1971 HUBBS: A NEW NONPARASITIC LAMPREY 163 

Seversmith, Herbert F. 

1953. Distribution, morphology, and life history of Lampetra aepyptera. a brook lamprey, in Maryland 
Copeia, 1953 (4): 225-232, figs. 1-^. 

Snyder, John Otterbein 

1908a. Relationships of the fish fauna of the lakes of southeastern Oregon. Bull. U.S. Bur. Fish., 27: 69-102, 

figs. 1^, 1 map. 
1908b. The fishes of the coastal streams of Oregon and northern California. Bull. U.S. Bur. Fish., 27: 
153-189, figs. 1-5, 1 map. 

Svetovidova, A. A. 

1948. Otikhookeanskoi minoge Entosphenus tridentatus (Gairdner) v sovetskoi chasti Beringova morya (On 
the Pacific lamprev Entosphenus tridentatus (Gairdner) in the Soviet part of the Bering Sea). Dokl. 
Akad. NaukSSSR,61 (1); 151-152, fig. 1. 

Vladykov, Vadim D. 

1950. Larvae of eastern American lampreys. I. - Species with two dorsal fins. La Naturaliste Canadien, 
77 (3-4): 73-95, figs. 1-13. 

1960. Description of young ammocqetes belonging to two species ot lampreys: Petromyzon marinus and 
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Vladykov, Vadim D., and W. I. Follett 

1958. Redescription of Lampetra ayresii (Giinther) of western North America, a species of lamprey 

(Petromyzontidae) distinct from Lampetra fluviatilis (Linnaeus) of Europe. J. Fish. Res. Bd. Canada, 

15(1): 47-77, figs. 1-15. 
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America. J. Fish. Res. Bd. Canada, 22 (1): 139-158, figs. 1-9. 
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Fish. Res. Bd. Canada, 24 (5): 1067-1075, figs. 1^. 

Zanandrea, Giuseppe 

1951. Rilievi e confronti biometrici e biologice sul Petromyzon ( Lampetra) planeri. Bloch. Nelle acque della 
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1954a. Corrispondenza tra forme parassite e non parassite nei generi Ichthyomyzon e Lampetra (probiemi di 

speciazione). Boll. Zool., 21 (2): 461-466. 
1954b. Note sulla ecologia e distribuzione in Italia della Lampedra di ruscello (Lampetra planeri Bloch). Boll. 

Pesca, Piscicult. e Idrobiol., 29 (n.s. 8) (2), for 1953: 252-269. 

1955. La corrispondenza tra forme parassite e non parassite nei generi Ichthyomyzon e Lampetra nei 
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1956. Neotenia in Lampetra planeri zanandreai (Vladykov) e Tendocrinologia sperimentale dei Ciclostomi. 
Boll. Zool., 23 (2): 413^27, pis. 1-3. 

1957a. Neoteny in a lamprey. Nature, 179: 925-926. 

1957b. Esame critico e comparativo delle Lampedre cotturate in Italia. Arch. Zool. Ital., 42: 249-307, figs. 

1-5, pis. 1-3. 
1958a. Allri casi di Lamprede neoteniche e il lore apparato naso-faringeo. Atti 1st. Veneto Sci., Lett, ed Art., 

116: 179-191, pis. 1-10. 
1958b. Posizione sistematica e distribuzione geografica di Lampetra zanandreai Vladykov. Mem. Mus. Civ. 

Storia Nat., Verona, 6: 207-237, figs. 1-3, pis. 1-3. 
1959a. Speciation among lampreys. Nature, 184: 380. 
1959b. Lamprede parassite e non parassite nei bacino del Danubio e la nuova entita sistematica Eu- 

dontomyzon danfordi vladykovi. Arch. Zool. Ital.. 44: 215-250, pis. 1-2. 
1959c. Recenti ricerche sulle forme "appaiate" di Lamprede dell' Italia e del Danubio. Boll. Zool., 26 (2): 

545-554. 

1961. Studies of European lampreys. Evolution, 15 (4): 523-534, figs. 1-3. 

1962a. Rapporti tra continent! e isole nella biogeografia delle Lamprede in Italia. Boll. Zool., 28, for 1961: 

529-544. 
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Scripps Institution of Oceanography, University of California, San Diego; La Jolla, 
California 92037. 




^^ ^jc.c^ MUS. COMP. ZOOL. 

LIBRARY. 

JUN 41971 

HARVARD 
UNiVSRSlTYi 



RECENT OSTRACODES FROM CLIPPERTON ISLAND 
EASTERN TROPICAL PACIFIC 



EDWIN C. ALLISON AND JOHN C. HOLDEN 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



VOL. 16, NO. 7 14 MAY 1971 



-1 



RECENT OSTRACODES FROM CLIPPERTON ISLAND 
EASTERN TROPICAL PACIFIC 



EDWIN C. ALLISONt AND JOHN C. HOLDEN 



ABSTRACT. — The Recent ostracode fauna of Clipperton Island is derived from several biogeo- 
graphic regions. It includes: (1) new species of Eticythenira, Neocaiidites, Paradoxostoma. and 
Semicytherura; (2) Cytherelloidea praecipiia, Occ ultocytliereis angiista, Paracytheridea tschoppi 
and species of Triehelina and Bairdia representing a distinct Caribbean aspect; (3) Xestolehcris 
gracilis, Triehelina sertata, Sclerochilus sp. nov.. and Bairdia ritugerda clippertonensis subsp. 
nov. forming a weak Indopacific link; (4) a restricted west American aspect represented by 
Bairdia semuvillosa and Mini Ins convergens: and, (5) a cosmopolitan aspect provided by the 
circumtropical species Pseiidocythere caiidata. 

Clipperton Lagoon, open to the sea about 130 years ago, now supports a unique freshwater 
ostracode fauna consisting of new species of Potainocypris, Cypridopsis and Liinnocythere. 

Dominant species in the marine samples are Paracytheridea tschoppi and Mutihis convergens. 
Common associates of these are species of Semicytherura, Paradoxostoma and Xestolehcris in 
near-shore reef flat areas, and species of Macrocxprina. Neocaiidites, and Cytherelloidea farther 
from shore. Members of the Family Loxoconchidae. characteristic of comparable Indopacific 
habitats, are conspicuously absent at Clipperton Island. 

RESUMEN. — La fauna de Ostracodos recientes de la isla Clipperton procede de varias regiones 
biogeograficas. Ahi aparacen los siguientes: 1 ) Especies nuevas de Eiicythenira. Neocaiidites, Para- 
doxostoma y Semicytherura: 2 ) Cytherelloidea praecipiia, Occiiltocythereis angiista, Paracythe- 
ridea tschoppi y especies de Triehelina y Bairdia que presentan un distintivo aspecto Caribe; 
3 ) Xestolehcris gracilis, Triehelina sertata, Sclerochilus sp. nov., y Bairdia ritugerda clipper- 
tonensis subsp. nov., que constituyen un debil eslabon Indo-Pacifico; 4) Bairdia semuvillosa y 
Miitilus convergens como representantes de las especies restringidas al oeste americano; y 5 ) la 
especie tropical Pseiidocythere caiidata como representante cosmopolita. 

La comunicacion de la laguna Clipperton con el Pacifico se abrio hace unos 130 anos, y 
actualmente contiene una fauna excepcional de Ostracodos dulceacuicolas, como son las especies 
nuevas de Potamocypris, Cypridopsis y Limnocythere. 

Las especies dominantes en las muestras marinas son: Paracytheridea tschoppi y Mutiliis 
convergens. Con estas se encuentran comunmente asociadas, especies de Semicytherura, Para- 
doxostoma y Xestolehcris en los arrecifes llanos proximos a la costa, y especies de Macrocyprina, 
Neocaiidites y Cytherelloidea en regiones mas alejadas. Es notable observar que los miembros de 
la Familia Loxoconchidae, caracteristicos de habitats similares del Pacifico e Indico, estan ausentes 
de la isla Clipperton. 

INTRODUCTION 

Clipperton Island, the easternmost Pacific atoll at latitude 10°I8' N, longitude 109° 

13' W (Figure 1), occupies a critical place in the scheme of tropical biogeography. It offers 

the only existing terrestial. littoral, or sublittoral habitats along the Clipperton Fracture 

, Zone (Menard and Fisher. 1958) or within the great tropical oceanic area known as the 

! East Pacific Barrier (Ekman. 1953) that separates Polynesian and west North American 

shallow marine environments. 

The atoll is oval in outline, about 3 by 4 km, and consists of a thin but unbroken ring 
of both loose and lithified coral debris with a single remnant of the igneous basement, 
j Clipperton Rock (29 m high), at the atoll's southeastern edge. A deep and completely 



tDeceased, 3 January 1971 

SAN DIEGO SOC. NAT. HIST., TRANS. 16(7): 165-214. 14 MAY 1971 



166 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




rkec/cc CA 



iqUA TOT^ AL eOUNUIl Cm ijENT , 



J 



ce&n 



SOUTH WATO[(IAL CUK^NT 



GAL4P4G0S 

ISLANDS 



Figure I. C'lipperlon Island and adjacent areas. Surface currents lor February adapted from Sverdrup. Johnson 
and Fleming (1*^42). Previous published works dealing with podocopid and platycopid ostracodes in the east 
Pacific are numbered within a circle in the approximate area of study. These are ( I ) Benson, 1959, (2) Benson and 
Kaesler, 1963 (3) Brady, 1 S80, (4) Crouch, 1949, (5) Hartmann, 1953, 1957a, 1957b, 1959a, 1959b, (6) Holden, 
1967, (7) Juday. 1907,'(S) LeRoy, 1943, 1945, (9) Rothwell, 1948a, 1948b, (10) Skogsberg, 1928, 1950, (11) 
Swam, 1967, (12) Swain and Gilby, 1964, ( 1 3) Swain and Gunther, 1969, and ( 14) Triebel, 1954, 1956, 1957. 

landlocked lagoon i,s fresh and generally palatable above 20 m but abruptly saline and 
stagnant below that depth (Sachet, 1962c). Early historical accounts of ocean connections 
(Sachet, 1963; Belcher, 1843) and in situ marine fossils, with a 370±I00 year radiometric 
age (Fergusson and Libby, 1962), indicate that the lagoon was at least periodically marine 
until recently. 

The geologic age of Clipperton Island is unknown. But the low incidence of endemism 
among the marine invertebrates does not support an old age for the faunas. 

On the other hand, the strong Caribbean character of the ostracode fauna supports the 
hypothesis that the Island has maintained a shallow water biota since the early Pliocene. 
Prior to that time a seaway extending through middle America linking the east Pacific with 
the Caribbean (Lloyd, 1963) would have allowed the North Atlantic Equatorial Current to 
sweep from east to west over the Colombian Basin into the Pacific at the latitude of 
Clipperton Island and could readily account for the Caribbean ostracode species now living 
there. 

The marine invertebrate fauna is an impoverished one in terms of diversity. It is 
composed principally o'i central Pacific (Indopacific) and tropical west American (Pan- 
amic) species. Many of these species are known to have tloating larval stages of long 
duration or to be potentially subject to dispersal by rafting. Indopacific and Panamic 
elements are almost equally represented in the inshore faunas, although the ratio of species 



1971 ALLISON AND HOLDEN: CLIPPERTONOSTRACODA 167 

representative of these provinces varies somewhat from group to group. Mixtures of 
Indopacific and Panamic species in the shallow marine faunas of Clipperton Island mark a 
blending of these two biogeographic provinces which otherwise are clearly distinct 
(Hertlein and Emerson, 1953; Emerson, 1967). No modern Panamic species is known to 
have dispersed farther westward than Clipperton Island. A small group of Indopacific 
species which have crossed the East Pacific Barrier (Hertlein, 1937; Briggs, 1961; 
Emerson, 1967) is almost completely represented in Clipperton Island faunas, thus 
suggesting the islands role as a stepping stone. The failure of many other species to effect 
westward or eastward dispersals once having reached Clipperton Island is one of the great 
problems presented by that island and its faunas. Shifting Pacific North Equatorial 
(westward) and Equatorial Counter (eastward) surface currents (Figure 1) as well as 
subjacent currents, cross the eastern Pacific at the latitude of Clipperton Island, providing 
possibilities for faunal dispersal in both directions (Wyrtki, 1965; U. S. Navy Hydro- 
graphic Office, 1947, 1950, 1966). 

The biogeographical importance of Clipperton Island, as well as the attraction of a 
remote and scarcely known island, inspired brief visits by biologists before 1956. Two 
expeditions with more ambitious aims were made possible in October-November 1956 and 
August-September 1958 through the participation of the University of California Scripps 
Institution of Oceanography in programs of the International Geophysical Year. The 
research vessel Spencer F. Baird, commanded by Captain Alan W. Phinney, provided 
transportation in both instances. The late Conrad Limbaugh served as scientific party chief 
for both expeditions. A single dredge haul from a subsequent S.I.O. cruise, local- 
ity B-8558, provided the only additional biological materials to which we have had 
access. Samples and field notes on which the present account of Clipperton Island 
ostracodes is based are the work of Allison who accompanied both the 1956 and 1958 
expeditions. Sediment and algae samples which were the source of the ostracodes dealt 
with here, were collected by free and SCUBA diving by Allison and Limbaugh except for 
the dredge sample at station B-8558. The most comprehensive descriptions of the history, 
geography, geology, and biology of Clipperton Island are to be found in published works of 
Marie-Helene Sachet (1960, 1962a, 1962b, 1963), who was one of the participants of the 
1958 expedition. 

FAUNAL CHARACTERISTICS OF THE OSTRACODA 

The marine ostracode fauna of Clipperton Island, like those of the other marine 
invertebrates there, is impoverished but shows diverse biogeographic affinities. Nine 
species are described as new and are considered here as endemics. These may, in fact, 
refiect our poor knowledge of Pacific ostracodes. Areas from which eastern Pacific 
podocopid ostracodes have been described are shown in Figure 1 . 

The ostracode samples forming the basis of this account represent freshwater lagoon 
and various marine reef and off-reef habitats. Species distributions are outlined tentatively 
on the basis of six samples collected according to field evaluations of physical environmen- 
tal factors and associated larger organisms. Species abundances, living-nonliving and 
distributional relationships are shown in Table 1 . 

Freshwater species. — Cypridupsis uceanus sp. nov., Limnocythere viaticum sp. nov., 
and Potamocypris insularis sp. nov., are abundant in Clipperton Lagoon. All presumably 
were introduced within the last 130 years after the last sea connections were blocked and 
marine conditions were replaced by the existing freshwater (Belcher, 1843). Only the 
unlikely possibility of prior introduction to, or evolution in, permanent ponds along the rim 
of the atoll, between the sea and the formerly marine lagoon, could account for a 



168 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

freshwater ostracode history dating earlier than 130 years ago. It is unlikely that such 
ponds ever existed on the narrow rimed atoll. The ostracodes probably were introduced by 
marine birds which frequent the island during their migratory llights. 

Disarticulated valves of several marine species occur in the lagoonal samples and 
probably represent former marine conditions there. Bairdia semuvillosa appears to 
represent former marine conditions in the lagoon. It does not occur in existing marine 
habitats around the island, though it is reported living in a wide diversity of west American 
habitats (Benson, 1959; Swain, 1967) and would appear to tolerate a wide range of 
conditions. 

Water in the lagoon varies in surface salinities from less than 0.1% to greater 
than 5.0%, depending on seasonal variations in rainfall (Sachet, 1962b). Below about 20 
m the water is saline with abundant sulfides and without evidence of an invertebrate fauna. 

Marine species. — Known distributions of the ostracodes which occupy the marine 

'linbitats give no clear indication of a dominant biogeographic relationship. Eucytherura 

binocula. Mutilus convergens clippertonensis, Paradoxostoma limhaughi. and Semi- 

cytherura qiiadraplana apparently represent an indigenous aspect of the Clipperton Island 

ostracode faunas. 

Five species have Caribbean affinities, Bairdia sp., Triebelina rugosa (not T. bradyi in 
the sense of Puri, 1960), Paracytheridea tschoppi, Occultocythereis angusta, and Cytherel- 
loidea praecipua. Paracytheridea tschoppi first appears in Miocene rocks of Trinidad, and 
is found living in the Caribbean and tropical eastern Pacific (Panamic province). Species of 
the genus Occultocythereis are common in early Tertiary deposits of North America and 
Europe (Morkhoven, 1963:197) and now occur in the Mediterranean (Muller. 1894), off 
the coast of Africa (Brady, 1911), and in the Caribbean. Occultocythereis angusta, 
described originally from Madeira Island, northwest Africa (Brady, 1911: "cythere 
deformis") also occurs in the Caribbean as far back as Miocene (Bold, 1963). Apart from 
its discovery at Clipperton Island, the genus Occultocythereis is unknown elsewhere in the 
Pacific. Bairdia sp. appears closely related to the undescribed Caribbean species Bairdia cf. 
B. tuherculata of Puri (1960). Triebelina rugosa and Cytherelloidea praecipua occur only 
in the modern Caribbean. Neocaudites is likewise a characteristic Caribbean genus 
(McKenzie. 1967), though we are aware of one species living off Dakar, Africa (unpub- 
lished), and two others (one fossil and one Recent) in the Hawaiian Islands (Holden, 1967). 
The Clipperton form, N. pacifica pacifica is considered subspecifically distinct from the 
living Hawaiian form, N.p. minima. 

Indopacific and Panamic faunal aspects, clearly evident among associated Clipperton 
Island marine invertebrates, are weakly represented. Xestoleberis gracilis, Sclerochilus 
sp., and Triebelina serata may be Indopacific taxa, as might also Bairdia ritugerda 
clippertonensis subsp. nov. The absence of the Loxoconchidae is striking because one or 
more species of Loxoconcha and Lo.xoconchella are commonly represented in island 
faunas of the Indopacific. Bairdia semuvillosa, probably restricted to the extinct marine 
fauna of Clipperton Lagoon, provides the only evidence of a direct Panamic-Clipperton 
Island link. Paracytheridea tschoppi occurs in the Panamic Province but probably has its 
origin in the Caribbean. 

Pseudocythere caudata is possibly a true cosmopolitan species. Other widely dis- 
tributed species seem to be restricted to 2 or 3 provinces, as defined by other marine 
invertebrate groups. 

Two species, Mutilus convergens and Paracytheridea tschoppi, dominate all of the 
marine samples, accounting for at least 50 "^"f of the individuals in each. 

Living specimens of Paradoxostoma limbaughi and Sclerochilus sp. occur only on 



1971 ALl ISON AND HOI DEN: CLIPPHRTON OSTRACODA 169 

intcrtidal and slightly subtidal (locality B-4241) areas of the reef fiat. They belong to 
genera known to live on marine plants. Xestuleberis gracilis also seems to prefer littoral 
conditions but is represented by one living specimen and by several dead valves in deeper 
water. Brady (1890) described that species as living in reef and shore pools of the tropical 
Pacific. 

Living specimens of Seniicytherura quadraplana occur only in sample B-6100, just 
beyond the outer edge of the Clipperton reef flat, but associated species in the intermediate 
area between reef (Tat (B-4241) and deeper outer slope (B-6120) samples range variously 
shoreward and seaward. 

Deeper habitats on the outer slope, beyond the outer edge of the ''ten-fathom terrace" 
appear to be faunally distinguished by Neocaudites pacifica and Cytherelloidea praecipua 
living in association with abundant Bairdia teeteri and with the ubiquitous Para- 
cytheridea tschoppi and Mutilus convergent clippertonensis. The deepest Clipperton 
sample. B-8538. at a depth of 92 m, lacks living ostracodes, although it contains numerous 
valves of species found living in shallower samples. 

METHODS 

Detailed descriptions are presented for (1) all new species, (2) those that have been 
inadequately described elsewhere, and (3) those of the Clipperton population that differ 
somewhat from other populations. The term "aff." is used here to indicate a close 
relationship between the Clipperton species and the species named. Whether they are 
conspecific or not is impossible to determine based on the available information. The use of 
"cf." denotes only a comparison to the species named and the two are probably distinct 
species. 

Most primary (holotypes) and some secondary types (paratypes and hypotypes) are 
reposited in the collections of the U. S. National Museum (USNM), Washington, D. C, 
and some are in the collections of the San Diego Society of Natural History at the 
Museum of Natural History, San Diego, California (SDNH). 

Measured specimens are adult instars unless otherwise indicated. Statistical measure- 
ments are computed at the 95 per cent confidence limits (± two standard deviations). All 
measurements are in microns (/t). 

Clipperton Island Ostracode Localities 

All samples (fig. 2) are assigned University of California Museum of Paleontology 
locality numbers. Most of the material, except ostracode types and minor parts of the 
samples, will be stored at the Edwin C. Allison Center for the Study of Pacific Faunas, San 
Diego State College. 

B-4244 - West side freshwater lagoon; on fossil reefs and in surrounding calcareous 

sands; depth approximately 4 m. 
B-4247 — West side freshwater lagoon; in sediment on steep slope off lagoon shelf; 

depth 8-10 m. 
B-4241 Reef flat off north side of island inshore from weakly developed algal ridge; 

on algae and in calcareous sediment between widely spaced coral heads 

I Porites and PocillopuraK depth intertidal to I- '2 m (in channels). 
B-6100 Approximately 100 m off outer edge of reef flat on north side of island; in 

sediment from broad sand patches near remains of sunken ships; depth 6-8 

m. 
B-6I()1 Approximately 100 m off outer edge of reef flat on north side of island, 

opposite U.S.N.H.O. marker, about 30 m inshore from outer edge of most 



170 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 2. Clippcrlon Island station locations. .Areas within circles indicate approximate station positions. 

prominent submarine terrace, northwest of major sandy areas (B-6I00); in 
small sediment pockets between and beneath massive living corals (mostly 
Pavona, Poriies, and Pocillopora) which cover bottom; depth 10-12 m. 

B-6 1 20 - Steep slope off north side of island opposite west end of near breach in atoll 
margin (formed by waves during period between 1956 and 1958 expedi- 
tions), below slope break at outer edge of principal submarine terrace; in 
sediment between blocks of dead coral and sparse cover of living herma- 
typic coral; depth 40-45 m. 

B-8558 - (CARR 11 8 D)— Dredged living (ahermatypic) and dead coral debris and 
calcareous sand from slope olT south-eastern side of Clipperton Island 
(10°19'N, 109°12"W); depth 92 m. Scripps Institution o'i Oceanography 
expedition CARROUStL (R/V Spencer F. Baird). 1 1 August 1964.^ 



\91\ 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



171 



^~~~~~^^^^ AND 

SPECIES ^-^™ 


(B-4244, B-4247) 

LAGOON 


(B-4241) 

REEF 


(B-6100) 

6-8ni. 


(B-6I0I) ■:;• 
I0-I2m. 


^nV (B-6120) 

 ■:^40-45m. 


(0 

eo- 

30 
(B-e558) 40- 

92 m. •"'■ 
so 


Bairdia teeter i 


2 




2 


1 -' 




2 






B. ritugerda clippertonensis 




1 




1 


10 




B. simuvlllosa 


7 












8. sp. 










2 




Triebelina r-ugosa 










3 


1 


T. sertata 




2 






6 




l^acrocyprina vargata 








■^^7«^^ 


148 




Potamocypns insularis 












Cypridopsis oceanus 














Pontocypris (?) sp. 




1 






2 




Pseudocytttere caudata 










1 




Eucytt)erura binocula 










7 


3 


Paracyttieridea tschoppi 












9 








Semicytherura quadaplana 








1 


1 




Mutilus cor)vergens clippertonensis 


5 










22 


■■'■^250^""^ 


^^193^"^ 


^■^^207^^" 


^■^"321""""™ 


Limnocythere viaticum 














Paradoxosfoma limbaughi 




—^13 








1 


Scieroctiilus sp. 




^^^3b^^ 






5 


8 


Neocaudites pacifica pacifica 












3 


Occultocythereis angusta 










2 


1 


Xestoleberis gracilis 




16 






3 


1 


X off. X. eulitoralis 










3 


1 


'Cythere" cf "C," caudata 












1 


Cytherelloidea praecipua 




5 


3 


1 


i— ^2Si^— 




TOTAL OSTRACODES 


ill 323 


26. j 


343 


742 

1 


53 



Table L Ostracode species-localit> check list. Heav\ lines indicate that some or all the individuals contained 
soft parts and are therefore inferred to have been livina at that localil\. 



Order Podocopida Muller. 1894 

Suborder Podocopina Sars, 1866 

Superfamily Bairdiacea Sars, 1888 

Family Bairdiidae Sars, 1888 

Genus Bairdia McCoy, 1844 

Bairdia simuvillosa Swain, 1967 

Fieure 3 



172 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Bairdia simuvillosa Swain, 1967:34. pi, 1. tigs. 2a-l', 8; lc\l tigs. 30c-d, 32. 43a; not Bairdia sinnivillusa: McKenzie 

and Swain. 1967:2S3. pi. 30, tig. i. ^ 
Bairdia sp. all". B. verdcsensis: Benson. 1959:42, pi. 1, tig. 6; pi. 8. tig. 16. 

Diagnosis. — Elongate Bairdia. posteriorly tapered in side view, with straight venter; 
greatest height in anterior third, greatest width just anterior to midlength; postercdorsum 
slightly concave up due to brief hump on caudal process. 

Description. — In side view: anteroventer evenly rounded; venter straight or slightly 
concave; posteroventer gently rounded to pointed posterior; posterodorsum slightly convex 
anterior to brief hump on caudal process; dorsum and anterodorsum almost straight, 
divided by a rounded anterocardinal angle. Left valve overlapping right valve along all 
margins except at extreme posterior ventral part of pointed caudal process. In dorsal view: 
carapace roughly diamond-shaped; greatest width just anterior midlength. Surface of 
valves smooth, marginal denticles absent, even in younger individuals. 

Duplicature moderately wide; anterior and posterior vestibules large. Fused part of 
duplicature transected b\ abundant simple radial pore canals, about 50 anteriorly, fewer 
posteriorly. Normal pores abundant, small, relatively few in center of carapace. 

Adductor muscle scars tending to fuse, pattern of an elongate scar above two larger 
irregular scars which in turn top two smaller oval scars. Dimorphism not observed. 






1 igurc 3. Bairdia siiiiuvilLisa Swam. l'Hi7. a-b. h\pot\pc. LJSNM 128066: a. righl \al\c \icw ofadult carapace: 
b. dorsal \iew oT adult carapace, c. h\pol\pe. IjSNM 128067; interior otadidt right \al\c. 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



173 



866 


510 


396 


850 


465 


187 


787 


449 


346 


800 


443 


345 


801 


463 


362 



Dimensions. — Length Height Width 

H\ polype, USNM 128066. Adult carapace, sta. B-4244, 47 

Hypotype, USNM 128067. Adult right valve, sta. B-4244, 47 

Hypotype, SDN H 04 1 89. Adult carapace, sta. B-4244, 47 

Hypotype, SDN H 04 1 90. Adult carapace, sta. B-4244, 47 

Hypotype, SDN H 04 1 9 1 . Adult carapace, sta. B-4244, 47 

Discussion. Seven specimens were found only at station B-4244-47 in the brackish- 
freshwater lagoon and are apparently relics from a past marine condition. 

This species is identical to a species found in the Gulf of California and on the Pacific 
side of the peninsula at Todos Santos Bay. Another form from Scammon Lagoon 
(McKenzie and Swain, 1967) is not considered conspecific because it has a more rounded 
dorsum and posterior, and relatively fewer normal pores 






Figure 4. Bairdia ritugerda clippertonensis subsp. nov. a-c, holotype. SDNH 04192; a. lateral view of adult left 
vaKe; b. interior viev\ of adult left vahe: e. dorsal \ievv of adult left valve. 



174 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Bairdia ritugerda clippertonensis subsp. nov. 

Figure 4 

Diagnosis. — Centrally inflated Bairdia with greatest height at anterocardinal angle in 
anterior third; caudal process humped, slightly pointed at posterior-most part; duplicatures 
vestibulate; young with posteroventral marginal serrations. Subspecies B. r. clip- 
pertonensis is smaller (600-750 /O than B. ritugerda sensu stricto; less accuminate 
posteriorly. 

Description. — Carapace small for genus, adult length 600-750 /a; surface of valves smooth 
to inconspicuously pitted by large but shallow depressions. In side view: left valve much 
higher than right valve along dorsum and at inturned area; dorsal margin broadly arched, 
flattened in anterior third, sometimes flattened at midlength, slightly concave in posterior 
above humped caudal process; greatest carapace height in anterior third of length; 
anteroventeral margin smooth in adults, serate in young. In dorsal view: carapace inflated 
at midlength or just anterior to midlength; posterior and anterior extremities pointed. 

Duplicature wide, heavy; narrow vestibules present; straight or bifurcating radial pore 
canals numerous, up to 50 anteriorly, most false; normal pores small, numerous except 
around adductor muscle scar area. Eight adductor muscle scars in tight cluster near center 
of valve. 

Dimensions. — Length Height Width 
Holotype. SDNH 04192. Adult left valve, sta. B-6101 595 413 176 

ParatypcUSNM 128089. Adult left valve, sta. B-61 20 759 449 196 

Paratype,USNM 128090. Adult right valve, sta. B-6 120 755 413 150 

ParatypcUSNM 128091. Adult right valve, sta. B-6120 680 370 137 

Discussion. — The species is much smaller at Clipperton Island than that at Hawaii, where 
it reaches lengths of 1000/-1 and more (Holden 1967: 13). The size difference, together with 
ditlerences in shape of the carapace distinguish the two populations as separate subspecies. 
Its habitat preference is unknown as no living individuals were found. Ten specimens 
were found off the submerged terrace at 40-45 m, whereas only two specimens were found 
in shallower water, perhaps indicating a preference for moderately deep water. 

Bairdia teeteri sp. nov. 
Figures 5, 6 

Diagnosis. Bairdia with upturned pointed caudal process; valves heavily pitted; antero 
and posterolateral surfaces with horizontal ridges giving carapace a terminally blunt aspect 
as seen from above. 

Description. In side view: venter straight to slightly concave downward, anteroven- 
ter and posteroventer about equal in length and convexity; posterodorsum and anterodor- 
sum about equal in length and inclination from horizontal, each slightly concave up; 
dorsum straight to slightly rounded. Left valve strongly over-reaching and over-lapping 
right valve in dorsal region, with low keel along highest points of dorsum; horizontal 
anterolateral ridge developed at midheight; horizontal posterolateral ridge extending along 
pointed, upturned caudal process. Possible sexual dimorphism expressed by relatively 
lower form (cf?) with height/length ratio =0.54 compared to (9?) 0.60. 

In dorsal views: anteromost and posteromosl parts of horizontal lateral marginal 
ridges sometimes knob-like giving carapace terminally blunt appearance; centrolateral 
region inllated. compressed near margins; width/length ratio about 0.40; surfaces densely 
pitted. 






1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



175 



Hinge of " Bairdiopillata"-iype with small toothlets near posterodorsal and antero- 
dorsal extremities in right valve and corresponding tiny sockets in left valve. Duplicature 
wide, heavy, traversed by sparse simple radial pore canals numbering about 15 anteriorly 
and posteriorly, tending to occur in pairs. Vestibules shallow. Adductor muscle scar 
pattern with eight equant scars — a center scar with seven surrounding it; three smaller 
mandibular scars just anteroventral to adductor group. 

Dimensions. — 

Holotype. USNM 128093. Adult carapace, sta. B-6120 
Paratype, SDNH 04193. Adult left valve, sta. B-6101 
Paratype. SDNH 04193. Adult right valve, sta. B-6101 
Paratype, SDNH 04194. Adult carapace, sta. B-6120 
Paratype, SDNH 04195. Adult left valve, sta. B-6101 
Paratype, USNM 128092. Penultimate carapace, sta. B-6120 
Paratype, SDNH 04196. Penultimate carapace, sta. B-6120 



ength 


Height 


mdth 


800 


483 


333 


750 


435 


190 


749 


388 


117 


792 


461 


313 


695 


404 


165 


659 


367 


253 


612 


345 


229 



500 



400 



I- 

X 



300 



200 







o 


VIII • . 

• 


• 

• 
• 




VI 


VII 
• • • 






V 

>- 


> • 









400 



500 



600 700 

LENGTH u 



800 



900 



Figure 5. Length-height plot of tive growth stages of Bairdia leeleri sp. nov. from stations B-6120 (o). B-6101 
(o). and B-4241 (o). The group isolated by dashed lines are thought to be males showing higher length-height 
ratios (Kornicker, 1961 ). All measurements taken from entire carapaces or the larger left valves. 

Discussion. Bairdia teeteri is closely related to B. attenuata Brady. 1880, from the 
Indopacitic and possibly from otT the coast of west Africa (Egger, 1901 ) in general shape, 
ornamentation, adductor muscle scar pattern and duplicature. Holden (1967: 14) described 
the internal features of B. attenuata to which the present species can be compared. The 
important difference between the two species is the presence of horizontal ridges on the 
antero and posterolateral surfaces of B. teeteri which are lacking on B. attenuata. The 
species might be confused with B. bradyi Bold, 1957, which has similar ornamentation and 
somewhat the same shape in side view, but is much wider and diamond shaped in dorsal 



176 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



view, not laterally compressed as B. teeteri. Another species belonging to the B. attenuata 
group and closely related to the present species is Bairdia sp. c of Bold (1966) from Coco 
Solo, Panama. It appears to have a poorly developed horizontal ridge on the posterolateral 
surface. According to Bold (personal comm.) the species occurs on the Pacific side of Costa 
Rica in rocks of "Young Neogene" age. 







Figure 6. Bainlia leelcri sp. nov. a-b. holotypc, USNM 1 28093; a, right valve view of adult carapace; b, dorsal 
view of entire carapace, c-d, paratype, SDNH 04193; c. interior view of adult left valve, d, interior view of adult 
riizht valve. 



At Clipperton Island sizes of individuals ditTer consistently between the stations B- 
6120 and B-6101 (see text-fig. 5). The adductor muscle scar pattern and the "Bairdiopil- 
laia" -lype dentition seem to be consistent as are other features and size dilTerences 
apparently are not ta.xonomically significant. 

The species is named for James Wallis Teeter, who in 1966 recognized its uniqueness 
during a study of British Honduras ostracodes. 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



177 



Bairdia sp. indet. 

Figure 7 

Description. — In dorsal view: carapace elongate, cylindrical, densely pitted, dark amber 
colored; dorsal margin arched, parallel with arched venteral margin; posterodorsal margin 
straight, angled ~ 45° from horizontal; anterior margin bluntly rounded beneath sharply 
angled anterocardinal angle. In dorsal view: carapace width about equal height along mid 
4/5 o{ length; terminally blunt; anterior and posterior valve junctures with small lip-like 
ridge. 

Anterior duplicature wide with large vestibule; posterior vestibule moderately wide 
with outer marginal half fused. Radial pore canals simple, straight, many occupying 
marginal denticles, alternating with interspaced false radial pore canals. Normal pores 
small, open type, interconnecting internal pit to external. Muscle scars not observed. 

Dimensions. — Length Height Width 

Specimen, SDNH 04197. Adult right valve, sta. B-6 120 664 289 136 

Specimen, USNM 128068. Penultimate? Left valve, sta. B-6120 471 232 99 






Figure 7. Bairdia sp. a-c, specimen, SDNH 04197; a, lateral view of adult right valve, b, dorsal view of adult 
right valve; c, interior view of adult right valve. 

Discussion. — Only two specimens, of which one was an adult, were found at station B- 
6120. The good condition of the adult carapace, including original coloration, suggests that 
the species is living close by, perhaps in shallower water. The inflated cylindrical carapace 
is indicative of a group of bairdiids including Bairdia acanthigera Brady from Cape Verde 
at 1020 1 150 fms, B. tuherculata Brady from the Admiralty Islands at 16-25 fms, and B. 
hanaumaensis Holden from the Hawaiian Islands at about 5 fms. The general shape alone 
of these species would seemingly justify their assignment to a new genus. 



178 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



The species is closely related and possibly conspecific with a Caribbean species listed 
as Bairdia cf. B. tuherculata by Puri (1960), but ditTers primarily by being more elongate 
and having a higher anterior margin as viewed from the side. 






Figure 8. Triebelina sertata Tricbcl. 1948. a-c. hypotype, USNM 128069; a. right valve view of adult carapace; 
b, dorsal view of adult carapace; c. interit)r view of adult right valve. 

Genus Triebelina Bold, 1946 

Triebelina sertata Tr\ehe\, 1948 

Figure 8 

Triebelina indopacifica van den Bold, 1946: 74, Fig. 7 in part . 

Triebelina sertata i:nthc\. 1948: 29. pi. 19, figs. la-h. 2a-d; Key. 1953: 158. pi. 1. tig. 5; Puri. 1960: 132. figs. 3. 4; 

(luha. 1968: 59, pi. 5. tig. 1. 
Triebelina sp. cf. T. cubensis Kingma, 1948: 69. pi. 7. fig. 4. 

Diagnosis. — Carapace robust, pitted, widest at two large swellings on each valve along 
midlength; strong dorsal ridge curving downward in posterior part of left valve, confined to 
dorsum in right valve. 
Description. See Triebel (1948) for a complete description of the species. 

Dimensions. Length Height Width 

Hypotype, USNM 128069. Adult left valve, sta. B-61 20 572 310 170 

Hypotype, USNM 128069. Adult right valve, sta. B-61 20 570 283 146 



1971 ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 179 

Hypotype, SDNH 04199. Penultimate left valve, sta. B-6 120 484 244 142 

Hypotype, SDNH 04200. 6th instar, left valve, sta. B-6 120 409 213 125 

Discussion — Triebelina sertata and T. indopacifica are closely related (Triebel, 1948). 
The most conspicuous differences between the two are the lack of swellings in the 
dorsolateral areas of both valves and the reduction of the long ventrolateral ridge into two 
broad nodes on each valve along the midlength in T. sertata. 

According to Key (1953), Bold (1946) had a specimen of what was described as 
Triebelina sertata in his collection of T. indopacifica from Ceram, West Indies. Key also 
noted that the single valve of Kingma's (1948) Triebelina cf. T. cubensis, from the lower 
Pliocene of Sumatra, is conspecific to T. sertata. One notices that the computed length- 
height ratio from Kingma's data agrees well with those of other specimens of T. sertata but 
does not agree with his illustrations, which must be distorted. 

The species appears to be a shallow water inhabitant. At Clipperton Island it is found 
from six to 45 meters (none living). One of us (Holden) collected it along beaches at 
Vanuambalavu, Fiji; Puri found it on reefs in the Florida Keys; and, Triebel reported it 
from shallow water in the Red Sea. Key's material consisted of one valve each at five 
stations in the East Indies ranging in depth from 372 to 3221 meters probably representing 
redeposition. 

Triebelina rugosa sp. nov. 
Figure 9 
Triebelina bradyi : Puri. 1960: 1 32. pi. 6. figs. 7 8. 

Diagnosis. — Carapace small, length less than 500/i, relatively elongate, L/H ratio about 
2.0, valves nearly equal in height; carapace compressed with parallel sides; lateral surfaces 
with small prominent tubercles in posterior and anterior lateral areas, two distinct 
tubercles one above the other beneath posterior cardinal angle. 

Description. — In side view: carapace elongate, L/H ratio about 2.0; dorsal margin 
straight, subparallel with slightly concave downward ventral margin; posterodorsal margin 
deeply concave upward above serrate caudal process terminating at midheight; anterior 
margin denticulate beneath flattened anterodorsal margin. Valves unequally ornamented: 
left valve with more strongly developed short tuberculate vertical posterior ridge than right 
valve; right valve with two narrow horizontal, sometimes discontinuous, ridges inter- 
connecting anterior lateral tubercles with posterior vertical ridge; both valves tuberculate 
in anterolateral areas. In dorsal view: carapace compressed, L/W ratio about 2.8; sides 
flattened, parallel; caudal region compressed behind vertical posterior ridges of right and 
left valves. 

Duplicature wide, heavy, shallow vestibules present with straight, thin radial pore 
canals. Eight elongate, inclined adductor scars near midheight of valve interior. 

Dimensions. — Length Height Width 

Holotype, USNM 128094. Adult left valve, sta. B-61 20 478 237 167 

Holotype, USNM 128094. Adult right valve, sta. B-6120 477 221 167 

Paratype, SDNH 04198. Adult carapace, sta. B-6120 466 224 158 

Discussion. — The specimens from Clipperton Island are conspecific with a species 
identified incorrectly as Triebelina bradyi by Puri (1960) from the west coast of Florida, 
and also known to occur in shallow waters of the British Honduran carbonate shelf 
(Teeter, 1966). This Caribbean-Clipperton species is clearly distinct from the Indopacific 
T. bradyi which is larger (more than 500/'), higher and has a few broad swellings for 



180 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



ornamentation. Triehelina hradyi. in addition, lacks the heavily denticulate, broadly, 
evenly rounded posteroventral margin of T. rugosa. 

Triehelina rugosa may have a remote ancestor in Triehelina sp/498 of Kollmann 
(1963) of Triassic (Rhaetic) age from the European Alps. They are strikingly similar in 
outline and both have ubiquitous elongate pits for ornamentation. They differ in tubercle 
and swelling arrangement on the lateral surfaces and size of carapace with T. rugosa being 
less than half the size of T. sp/498. 

t 



o. ..  - 






Figure 9. Triehelina rii^usu sp. no\ . a-c, holotype, USNM I28U94; a, left valve view of adult carapace; b, dorsal 
view; c, internal view. 

Puri did not give the depth distribution of the species in the Caribbean; however, we 
presume it is a shallow water form. In the Caribbean it is found at Molasses Reef, off 
Tavernier, in the Florida Keys (Puri, 1960). At Clipperton Island the species occurs no 
shallower than 40 meters at station B-6120 on the rubble slope beneath the principal 
submarine terrace of the island. One valve was found at 92 m at station B-8558. 



Superfamily Cypridacea Baird, 1849 

Family Cyprididae Baird, 1849 

Subfamily Macrocypridinae Miiller, 1912 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



181 



Genus MacrocyprinaTr'\ehe\, 1960 
Macrocyprina vargata sp. nov. 

Figures 10, 1 1 

Diagnosis. — Carapace strongly arched, angled at highest point at mid-dorsum; posterior 
bluntly pointed; light brown color pattern in live specimens distinctive with broad 
somewhat inclined bands extending halfway down shell from cardinal angles, large 
circular light brown spot surrounding muscle scar area, and at dorsum. 

Description. — Carapace heavy, large, length 900-940 /x, light brown color pattern in live 
specimens consisting of two somewhat oblique broad bands extending half way down 
carapace from cardinal angles, large circular spot at center of shell corresponding with 
adductor muscle scar pattern, large spot at mid-dorsum of carapace tending to elongate 
and merge with central color spot. In side view: carapace reinform, dorsum highly arched, 
somewhat angled at midlength; ventral margin broadly concave downward; anterior 
margin evenly rounded, posterior margin bluntly pointed; right valve overlapping left valve 
in anterodorsum, posterodorsum, along venter. In dorsal view: carapace bluntly pointed at 
posterior and anterior; greatest width at midlength. Both sexes present; sexual dimor- 
phism not evident in carapace. 

Duplicatures wide, with irregular vestibules intruding into fused zone sometimes as 
little pockets from which one or two true or false radial pores extend; radial pore canals 
sparse for genus, some paired. Normal pores small, sieve type, about 40-50 in ventral half, 
sparse in dorsal half. Hinge of right valve of finely crenulate bar terminating posteriorly 
and anteriorly with small crenulate projecting cusps grading into terminal crenulate 
grooves about 1 10 /i in length. Ten adductor muscle scars located beneath midheight and 
just anterior to midlength; two mandibular scars located anteroventral to adductor group. 



500 



I- 
X 
l£  

ai 

X 



200 



















VIII 




















«: 
















1 
VI 


• 


















» 
















VI 


.H 


%. 














V 


• 
















IV 


• 
















III 


















II 


• 


•. 
















• 



















600 
LENGTH 



900 



r 



Figure 10. Length-height plot of seven growth sti'ges of Macrocyprina vargata sp. nov. from stations B-6120 
and 8-6101. 



182 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Length Height 



Dimensions. — 

Holotype. USNM 128095. Adult carapace, sta. B-6101 926 410 

Paratype, USNM 128096. Adult right valve, sta. B-6101 919 420 

Paratype, USNM 128096. Adult left valve, sta. B-6101 925 422 

Paratype, SDNH 04201. Penultimate carapace, sta. B-61 20 798 360 

Paratype, USNM 128097. Penultimate carapace, sta. B-6120 821 354 

Paratype, SDNH 04202. Adult carapace, sta. B-6120 937 430 

Paratype, USN M 1 28098. 6th instar carapace, sta. B-6 1 20 550 225 

Paratype, SDN H 04203. 6th instar carapace, sta. B-6 1 20 538 229 

Discussion. — The type species of the genus, Macrocyprina propinqua Triebel ( 1 
more evenly rounded dorsum, is more terminally pointed in dorsal view, and 
larger (950-1008 i«.) than the Clipperton species. The color pattern is similar. 



Width 
307 
316 
316 
254 
260 
314 
179 
194 

960) has a 
is slightly 
though of 







Figure 11. Mucrocvprina variiatii sp. nov. a-b. holotype, USNM 128095; a. lateral left valve view of adult 
carapace; b, dorsal view of adult carapace, c-e. paratype, USNM 12S(»6; c, interior view of adult left valve; d, 
dorsal view of adult Icl't valve; d, dorsal view of adult right valve, f, ejaculalory duct, f, third thoracic leg. 



1971 ALLISON AND HOLDEN:CLIPPERTON OSTRACODA 183 

greater relative size.and does not tend to form bands but rather spots in M. propinqua. 

Macrocyprina vargata is also like the southern hemisphere species M. decora (Brady, 
1866) in general shape though more terminally blunt, as seen from above, and smaller with 
adult lengths ranging from 900-940 /a as opposed to 1005-1010 ju. as cited by Brady (1866, 
1880). In addition, the color markings between the two species differ considerably 
(compare with Brady, 1880, pi. 6, figs. 8a-b). 

The species also resembles Macrocypris succinea MUller, 1894, from the Gulf of 
Naples in general shape but, again, is more bluntly pointed in dorsal view. In these two 
species the central muscle scar patterns are comparable each with the same number of 
scars in approximately the same relative positions. The two small frontal scars shown on 
Muller's pi. 13, fig. 25 do not appear on M. vargata, however. The male ejaculatory 
apparatus (Zenker's organ) in the two species has the same characteristics, i.e., a central 
spiny shaft terminating posteriorly in a smooth bulb-like structure and the same complexly 
twisted tubing. In M. vargata, however, the posterior bulb-like structure is much smaller 
and the central shaft and tubing are much narrower. Also, the central shaft possesses more 
and longer spines. Zenker's organ of A/, propinqua and M. vargata appear very similar. 

The specific name denotes the broad vertical color stripes shown in living individuals, 
vargatus (L.), "striped." 

Subfamily Cypridopsinae Kaufmann, 1900 

Genus Potamocypris Brady, 1870 

Potamocypris insularis sp. nov. 

Figure 12 

Diagnosis. — Smooth, highly unequivalved species of Potamocypris with posterior flange 
of left valve overreaching right valve. As seen from above, anterior terminating in sharp 
point canted slightly to the left. 

Description. — In side view: carapace high, length/height ratio about 1.6; length of adult 
600-700 /x; outline subtriangular. highest point just anterior to midlength at highly angled 
dorsum; ventral margin straight to slightly concave; posterior margin of right valve steeply 
truncate; bluntly pointed near venter in left valve; right valve larger than left valve, 
overreaching left valve along dorsum where it is considerably higher and along venter and 
anterior; left valve overreaching right valve posteriorly as a caudal flange. In dorsal view: 
length/width ratio from 2.5 to 2.9; outline irregularly lenticular; greatest width near 
midlength. anterior sharply pointed, posterior bluntly pointed. 

Calcified duplicature poorly developed, present only in left valve anterior. Radial pore 
canals short, simple. Normal pores numerous, small, open type. Hinge adont. Adductor 
muscle scar pattern composed of five scars, top scar elongate, second and third an oblong 
pair, fourth scar elongate, fifth scar small, circular. 

Dimensions. — 

USNM, Holotype 128099. Adult carapace, sta. B-4244, 47 
USNM, Paratype 128100. Adult right valve, sta. B-4244. 47 
SDNH, Paratype 04204. Adult carapace, sta. B-4244, 47 
SDNH. Paratype 04205. Adult carapace, sta. B-4244, 47 

Discussion. — Potamocypris insularis has only five scars in the adductor pattern, unlike 
most species of the genus which have six or seven. There is an apparent reduction occurring 
in the ventral part of the pattern. 

The closest living Potamocypris to Clipperton Island is P. islagrandensis which occurs 



Length 


Height 


Width 


692 


4r6 


250 


612 


333 


113 


701 


412 


258 


677 


392 


234 



184 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



in Lake Nicaragua, Central America. Potamocypris insularis is relatively higher, has a 
pointed posterior and has a different adductor muscle scar pattern than P. islagrandensis 
(Swain and Gilby, 1964). 



100 M 




100 M 






Figure 12, Potaniocvpris insularis sp. nov. a-b. hololype, USNM 128099; a. lateral left valve view of adult 
carapace; b, dorsal view of adult carapace, c-d. paratype. USNM 12S1(K); c, interior view of adult right \alve; d. 
interior view of adult left \alve. 

Genus Cypridopsis Brady, 1868 

Cypridopsis oceanus sp. nov. 

Figure 13 
Diagnosis. — Carapace small, 580 /a in length; smooth; moderately inflated (length/width 
= 1.60); greatest height and width near midlength. 

Description. — Carapace thin, transparent, smooth; living specimens covered with sparse 
short hairs; width slightly greater than height, length 1.60 times width. In side view: dorsal 
margin sloping off straight posteriorly and anteriorly from angled high point at carapace 
midlength; posterior and anterior margins similarly shaped, broadly rounded; ventral 
margin straight to slightly concave; valves somewhat unequal, left valve slightly over- 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



185 



reaching right valve anteriorly, being barely overreached by right valve posteriorly; left 
valve strongly overlapping right valve at ventral inturned area. In dorsal view: carapace 
ovolenticular, greatest width behind midlength, width slightly greater than height. 




Figure 13. Cypridopsis oceanus sp. nov. a-b, hoiot\pe. USNM 128101; a, lateral view of adult right valve; b, 
dorsal vie\\ ofadult right valve, c. paratype, USNM 128102; interior view of adult left valve. 

Anterior duplicature wide, fused zone narrow with many small simple radial pore 

canals; posterior duplicature half as wide as anterior. Adductor pattern of five equant scars 

in central field with sixth small scar in posteroventral part of field; antennal scars large, 

oblong, beneath and in front of adductor muscle scar pattern. Normal pores minute, 

sparse, evenly distributed. 

Dimensions. — 

Holotype, USNM 128101. Adult carapace, sta. B-4244, 47 
Paratvpe, USNM 128102. Adult left valve, sta. B-4244. 47 
Paratype, USNM 128102. Adult right valve, sta. B-4244, 47 
Paratype, SDNH 04206. Adult carapace, sta. B-4244, 47 
Paratype, SDNH 04207. Adult carapace, sta. B-4244, 47 
Paratype, SDNH 04208. Adult carapace, sta. B-4244, 47 
Paratype. SDNH 04209. Adult carapace, sta. B-4244, 47 



ength 


Height 


Width 


579 


328 


355 


544 


319 


326 


545 


316 


325 


562 


354 


356 


587 


344 


366 


548 


325 


350 


563 


339 


359 



186 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Discussion. — This species bears some resemblance to Cypridopsis vidua (O. F. Miiller, 
1776) but is much smaller, unpitled, and has a blunter posterior viewed from the side. Also, 
there are six adductor scars as in C. vidua but their relative positions differ (compare with 
Morkhoven, 1963, p. 48). The size of Cypridopsis oceanus is consistently less than 600 
microns compared with 700 microns for C vidua (Wagner, 1957). 

The actual salinity range of the lagoon when the species was collected is not known; 
however, it was palatable. Allison noted when diving in the lagoon that the salinity 
increased with depth. Breakers will occasionally reach the lagoon during storms. Consid- 
ering these factors, Cypridopsis oceanus probably has a much higher salinity tolerance 
than C. vidua which apparently cannot survive marine salinities greater than 0.8 % (Wagner, 
1957:1 10; Reyment, 1964:75). 






Figure 14. Pontocypris'^ sp. a-c, specimen, USNM 128070; a, interior view of adult left valve; b, dorsal view of 
adult left valve; c, lateral view of adult left valve. 

Subfamily Pontocypridinae Muller, 1894 

Genus Pontocypris Sars, 1866 

Pontocypris? sp. 

Figure 14 
Description. - Carapace accuminate posteriorly, terminating in a sharply pointed pos- 
terior in both dorsal and side views. In side view: greatest height at sharply angled point in 
anterior third; anterodorsum and posterodorsum sloping away from the highest point at 
angles of about 30° from the horizontal; posterodorsal margin almost straight, terminating 



ength 


Height 


Width 


740 


347 


140 


742 


342 


228 


726 


317 


119 


512 


227 


158 


524 


212 


90 


411 


170 


142 


325 


134 


117 



1971 ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 187 

in pointed ventral posterium; ventral margin straight except for slight convexity at inturned 
area. In dorsal view: carapace compressed, greatest width in anterior quarter, right valve 
overlapping left valve posterior to greatest carapace height in anterior third. 

Duplicature wide in both posterior and anterior parts of valve. Fused zones narrow, 
containing several straight, simple radial pore canals. About six oblong adductor scars 
located in region above inturned area. 

Dimensions. — 

Specimen USNM 128070. Adult left valve, sta. B-6101 
Specimen SDNH 04210. Adult carapace, sta. B-6120 
Specimen SDNH 0421 1. Adult left valve, sta. B-6120 
Specimen USNM 128071. 6th instar carapace, sta. B-6120 
Specimen SDNH 04212. 6th instar right valve, sta. B-6120 
Specimen SDNH 04213. 5th instar carapace, sta. B-6120 
Specimen USNM 128072. 4th instar carapace, sta. B-6120 

Discussion. — The carapace, as seen in side view, has the triangular shape of Pontocypris 
but the muscle scar pattern suggests the genus Propontocypris. The two genera originally 
were established on the basis of soft parts not preserved in the Clipperton collection. 

Pontocypris'!' sp. is best compared to P. accuminata Muller, 1894, from the Gulf of 
Naples. The Clipperton species has, however, a straighter dorsal margin in the posterior 
two thirds, is more posteriorly accuminate and internally it has a less extensive duplicature 
and lacks the typical Pontocypris muscle scar pattern. 

Superfamily Cytheracea Baird, 1850 

Family Bythocytheridae Sars, 1926 

G^nxxs Pseudocythere Sdx?,, 1866 

Pseudocythere caudata Sars, 1866 

Figure 15 

Pseudocythere caudata Sdvs. 1866:88: Brady. 1868:453, pi. 34, tigs. 49-52: Brady, 1880:144, pi. l,figs. 6a-d: Muller, 
1894:285, pi. 16, figs. 5, 10, 30-36: Tressler, 1941:102, pi. 19, fig. 15; Wagner, 1957:35, pi. 12: Benson, 1964:13, 
pi. 1, fig. 8; text-fig. 7. 

Pseudocythere I A Maddocks, 1966:62, text fig. 46, no. 2. 

Diagnosis. — Because there is little agreement on what the salient characteristics are that 
detine this species, a diagnosis is not presented here. 

Description. — Side view: dorsal margin almost straight from top of high truncate 
caudal process to anterodorsal cardinal angle; anterior margin broadly rounded; ventral 
margin concave downward at centrally located inturned area; posteroventral margin 
formed by broad compressed marginal flange. Valves ornamented by continuous, discon- 
tinuous, occasionally merging, narrow horizontal ridges everywhere except on most of 
caudal process and on posteroventral flange which are smooth. In dorsal view: valve evenly 
intlated along length excluding laterally compressed caudal process; width of carapace 
would measure one-half length in entire specimen. 

Duplicatures broad with large vestibules occupying one-half of duplicature width. 
Radial pore canals straight, some with enlargements near line of concrescences, sparse, 
about 10 anteriorly, relatively abundant in ventral half, about eight posteriorly. Normal 
pores not observed. Hinge weakly developed with elongate bar and subjacent groove. 
Adductor muscle scar pattern of three horizontally elongate scars in vertical row, bottom 
scar possibly two fused scars. Oval frontal scar anterior to topmost adductor scar. Soft 
parts not preserved. 



188 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Dimensions. — Length Height Width 

Hypotype, USNM 128073. Adult right valve, sta. B-6120 285 15^8 69 

Discussion. — Benson (1964:14) pointed out the improbability that all the reports of 
Pseudocythere caudata are referable to one species. However, no serious attempt has been 
made to separate this geographically widespread group into species or even subspecies. The 
single specimen found at station B-6120 is identified as P. caudata because it falls within 
the range of variation of other known populations and insufficient material does not allow 
a more critical analysis of it here. 

Further studies may show that more important differences occur between warm water 
and cold water forms, irrespective of depth of water, than between forms separated by 
great distances of longitude. This relationship is suggested by a close resemblance between 
the Clipperton Island specimen and another shallow water reef form from northern 
Madagascar (Maddocks, 1966). In side view, specimens from both areas lack the 
posteroventral spine, at least in the right valve, and are more quadrate, with almost parallel 
ventral and dorsal margins, than the subtriangular, spined forms reported from cold or 
deep water areas. Future taxonomists should pay particular attention to the number of 






Figure 15. Pseudocythere ccnidata Sars, 1866. a-c, hypotype, USNM 128073: a, lateral \ ieu of adult right valve: 
b, dorsal view of adult right valve: c, interior view of adult right valve. 



1971 ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 189 

adductor muscle scars present. Some authors find five scars in the pattern, others only 
four. Possibly there is a reduction in the number of adductor scars in warmer water forms; 
indeed, the specimen from Clipperton Island approaches a condition of only three 
adductor scars with the bottom two scars almost fused (see Figure 15c). A form illustrated 
by Wagner (1957, pi. 12) from the Quaternary of the Pays Basin closely resembles the 
Clipperton Island and Madagascar forms in those features discussed above and also has 
only four adductor scars, but its ecology is unknown. 

Pseudocythere caudata at Clipperton Island is considerably smaller than elsewhere, 
being only 285 microns long. The specimen is well developed internally and must be 
assumed to be an adult. 

Family Cytheruridae G. W. MuUer, 1 894 

Genus Eucytherura Muller, 1894 

Eucytherura binocula sp. nov. 

Figure 16 

Diagnosis. — Small Eucytherura, length 258-290/'., very wide in posteroventer; surfaces 
entirely reticulate, with swellings, tubercles and spines developed to various degrees; eye 
tubercles and internal occular sinuses large, distinct duplicature vestibulate. 

Description. — Carapace small, size variable, length 258-290 /»., males somewat smaller 
than females. In side view: dorsal margin generally straight, parallel with ventral margin; 
anterior margin flattened in dorsal half, strongly denticulate in rounded ventral half with 
four to five denticles and spines; caudal process blunt, near dorsum; posterior margin 
straight, obliquely angled at 45° beneath caudal process; surface of male valve usually with 
three large swellings; an interior subcentral swelling, posterodorsal swelling, and pos- 
teroventral swelling representing greatest width of shell, females without midswellings, 
more inflated; large smooth eye tubercle located just behind sharply angled anterocardinal 
angle in each valve; surfaces with deep reticulae, and variously developed, and variously 
spaced spines and tubercles. In dorsal view: carapace lanceolate (cT ) to sublenticular ( 9 ), 
greatest width always in posterior half at posteroventral swelling; caudal process com- 
pressed and pointed; median sulcus poorly developed. 

Posterior and anterior duplicatures of moderate width, each with small deep vesti- 
bulae tending to dip into the few, straight radial pore canals. Normal pores numerous, 
tending to occur in groups of up to three within the outlines of reticulae, usually 
accompanied by tiny conical projections deep within the reticulae, the number of conical 
projections approximates that of the pores. Hinge typical for genus: small entire terminal 
teeth of right valve separated by finely crenulate groove. Muscle scar pattern and soft parts 
not preserved. 
Dimensions. — 

Holotype, USNM 128103. Adult carapace, sta. B-6120 
Paratype, USNM 128104. Adult left valve, sta. B-6120 
Paratype, SDNH 04214. Adult right valve, sta. B-6120 
Paratype, SDNH 042 1 5. Adult carapace, sta. B-6120 
Paratype, SDNH 04216. Adult left valve, sta. B-8558 
Paratype. SDNH 04217. Adult carapace, sta. B-6120 

Discussion. — Two basic forms are present probably reflecting sexual dimorphism. The 
males are compressed dorsally and swollen at the subcentral and posteroventral areas, as 
shown in text figure 16a-b. These tend to be arrow-shaped in dorsal view as a result of the 
pronounced posteroventral swellings. The presumed females are more abundant and more 



ength 


Height 


Width 


258 


126 


188 


287 


156 


92 


277 


151 


75 


266 


152 


166 


191 


164 


100 


285 


167 


177 



190 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



inflated laterally, but are no wider, and tend to be lenticular in dorsal view. Holden 
(1964:413) noted a similar kind of dimorphism in Eucytherura spinata from the Upper 
Cretaceous of California. The typical type of dimorphism in Eucytherura results in lower 
and longer males (Morkhoven, 1963:357). 

Ornamentation is variably developed. In the inflated females, an arcuate row of about 
five or six tubercles runs from the eye tubercle to the posteroventral swelling via the 
subcentral area and then up to the posterodorsum (Figure 16g). In the males the tubercles 
are mostly lost at the expense of the various swellings. 

One of the most prominent features is the large eye tubercles. The species appears to 
be related to Eucytherura gihhera Miiller, 1894, which has a similar type of ornamentation 







Figure 16. Eiicvtherura hinucula sp. nov. a-b, holotype, USNM 12S103; a, lateral left valve view of adult 
carapace; b, dorsal view of adult carapace, c-d. paralype. USNM 128104; c, interior view of adult left valve; d. 
dorsal view of adult left valve, e, parat>pc. SDNH 04214; dorsal view of adult right valve, f, normal pores within 
reticulae as seen with transmitted light, g, generalized sketch sht)wing tubercle arrangement on the female 
carapace, reticulations not drawn in. 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



191 



and large eye tubercles. According to Bold (pers. comm.) the species is similar but not 
identical to species living in the Caribbean. 

The species is named with reference to its very large eye tubercles. 

Genus Paracytheridea Miiller, 1894 
Paracytheridea tschoppi Bold, 1946 

Figures 17, 18, 19 

Paracytheridea tschoppi van den Bold, 1946:85. pi. 16, figs. 6-7; van den Bold. 1957:245, pi. 4, fig. 7: Benson and 

Coleman, 1963:33. pi. 6, figs. 7. 9, 10, 20. 
Paracytheridea granti Swain, 1967:70 (in part), pi. 4, tigs. 10. 1 la. b, pi. 5, figs. 2a. b, 4a-c, 5, text fig. 47a. 

Diagnosis. — Sharply and prominently caudate Paracytheridea with posterodorsal swelling 
supporting 3-4 flange-like oblique ridges, horizontal alar ridge continuous to anterior 
margin; posterior toothlet complex in hinge of right valve well developed; projecting 
anterior toothlet complex poorly developed and not projecting. 

Description. — In side view: outline of dorsum and venter parallel due to posteroventer 
massive ala: dorsal and ventral margins actually highly and posteriorly accuminate, 
terminating in well developed pointed caudal process at posterior midheight; anterior 
margin of right valve broadly rounded, obliquely rounded in left valve due to extended 
anterocardinal wing. In dorsal view: greatest carapace width in posterior third, height/ 
length ratio of 0.65 to 0.75. Valves deeply sulcate at midlength in dorsal three-quarters 
dividing subcentral tubercle and highly inflated posterodorsal swelling. Ornamentation 
principally of flange-like ridges characteristically arranged as discussed further on. 

Duplicature wide, nonvestibulate duplicatures transected by sparse radial pore canals; 
radial pore canals mostly false, about 12 anteriorly, 3 posteriorly, one of which occupies 
conspicuous subcaudal dentical. Normal pores sieve type, sparse, sieve plate usually a 
horseshoe shaped structure with about 25 perforations. Hinge lobodont, right valve with 
prominent posterior element of five distinct toothlets, anterior element of five poorly 



1- 

UJ 

X 



iOO 














1 

VII 


:^r ^"' 








III 

• 


IV 

> 


V 


VI 

• • 

• 
1 






n 















100 



200 



300 



LENGT 



400 



500 



600 



H U 



Figure 17. Length-height plot of six growth stages of Paracytheridea tschoppi Bold from stations B-6101 and B- 
6120. In all cases measurements were taken on entire carapace or the larger left valves. 



192 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

developed toothlets, wavy median groove with about 20-25 notches. Five adductor muscle 
scars on posterior side of well developed circular subcentral depression, second and third 
scars up may be a divided scar preserving the fundamental pattern of four scars for the 
adductor group. Frontal scars located on anterior side of subcentral depression numbering 
six in two pairs of three, one group above the other. 
Sexual dimorphism not observed. 

Dimensions.-^ The following information was determined from a collection of 35 adult 

carapaces: L = 520 ±20. 6 p.; H = 261 ± 18.4 /x. Nineteen adult carapaces gave a mean width 

of 380 /J. with a range from 348 /x to 405 p.. 

Dimensions. — 

Hypotype, USNM 128074. Adult right valve, sta. B-6101 

Hypotype, USNM 128074. Adult left valve, sta. B-6101 

Hypotype, SDNH 04218. Adult carapace, sta. B-6101 

Hypotype, SDNH 04219. Adult carapace, sta. B-6101 

Hypotype, SDNH 04220. Penultimate carapace, sta. B-6101 

Hypotype, USNM 128075. Penultimate left valve, sta. B-6101 

Hypotype, USNM 128076. 6th instar carapace, sta. B-6101 

Hypotype, USNM 128077. 5th instar carapace, sta. B-6101 

Hypotype, USNM 128078. 4th instar carapace, sta. B-6100 

Discussion. — Paracytheridea tschoppi has not previously been reported from the Pacific 
region though it is known to be widespread in the Caribbean and parts of the Gulf of 
Mexico (Bold, 1946, 1957; Benson and Coleman, 1963). We believe that minor differences 
in shell morphology are not sufficient evidence to separate the closely related populations 
of P. tschoppi in the Gulf of California and Clipperton Island from those in the Caribbean 
and Gulf of Mexico. 

Terminology is introduced in Figure 18 for the ridge arrangement of Paracytheridea. 
It is assumed that the positions, if not the degree of development, of ridges ornamenting 
the valves of this genus are genetically controlled. 



ength 


Height 


Width 


514 


241 


192 


517 


267 


192 


524 


251 


360 


530 


275 


367 


449 


209 


300 


430 


204 


150 


364 


167 


237 


300 


142 


203 


203 


102 


143 




Figure 18. Schematic diagram oi Paracytheridea ornamentation. A, L, P, and V represent the anterior, lateral, 
posterior, and ventral ridges, respectively. 

The Pliocene to Holocene Paracytheridea granti Le Roy, 1943 of California and Baja 
California has been confused with P. tschoppi. Paracytheridea granti lacks the pronounced 
posterodorsal swelling and possesses a more prominent posterodorsal cardinal angle than 
P. tschoppi. In P. tschoppi a P2or P3 extends into the posterocardinal region. Ridge 
ornamentation in P. granti is distinctive with a P2 or P3 running continuously into L| 
which joins A 2 and which is the only horizontal ridge reaching the anterior margin. In P. 
tschoppi. both At and V, reach the anterior margin. In P. granti V\ ultimately joins V3 



1971 



ALLISON AND HOLDEN; CLIPPERTON OSTRACODA 



193 



and merges with A^. 

Paracytheridea tschoppi is characterized by a ridge arrangement as follows: P2 is well 
developed and bifurcates near the median sulcus and can be traced, or extrapolated, across 
the sulcus to L| and Lt respectively. P4 is interrupted medially and is traceable to L3. L] 
and L3 merge in the anterior part of the subcentral tubercle and join A-, which continues to 
the anterior margin. A strongly developed V| is continuous from the posterior end of the 
alae to the anterior margin and is subparallel with L3-A2 in the anterior half of the shell. 
V[ and Vt are equally developed. 




Figure 19. Paracvtheridea tschoppi Bold, 1946. a, hypotype, SDNH 04219; lateral right valve view of adult 
carapace, b, hypotype. SDNH 04218; dorsal view ol" adult carapace, c-f, hypotype, USNM 128074; c, interior 
view of adult left valve; d, interior view of adult right valve; e, f, dorsal view of adult right and left valves 
respectively, normal pore greatly enlarged as seen with transmitted light. 



194 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Genus Semicytherura Wagner, 1957 

Semicytherura quadraplana sp. nov. 

Figure 20 

Diagnosis. — Small Semicytherura with high pointed caudal process and ridge ornamenta- 
tion resulting in minutely pitted posteroventral, anteroventral, and central fields when 
viewed from the side; alate as seen from above. 

Description. — Carapace heavy, small, 260 to 290 /x long. In side view: dorsal margin 
nearly straight, parallel with straight ventral margin: venter very wide and flat; anterior 
margin obliquely rounded, ventral half with four stubby marginal knobs; posterior margin 
truncate beneath high, pointed caudal process; periphery of valves with continuous smooth 
ridge, doubled along anterior margin and complex along dorsal margin; smooth lateral 
ridge departing at right angle from anterior ridge at midheight, swinging down to venter 
along the edge of wide alar process, then swinging irregularly back up to posterocardinal 
angle thus creating two nearly equal fields in anteroventer and posteroventer with larger 
central field between; compressed caudal area a fourth field; right valve somewhat higher, 
overreaching left valve along dorsum. In dorsal view: carapace compressed in dorsal half; 
greatest width along ventral midlength on well developed alar process; anterior blunt due 
to doubled marginal ridge system; posterior compressed, pointed at caudal process. 

Duplicatures broad; posterior duplicature greatly extended inward, almost to middle 
of valve; posterior radial pore canals mostly false, some passing through marginal spine at 
posteroventer, at least one running full length of caudal process; anterior duplicature wide, 
with 15 to 20 irregular, enlarged, sometimes dividing radial pore canals; no vestibules. 
Normal pores numerous, tiny, in small clusters of one to 18, each cluster apparently 
narrowing to small external pit. Hinge elements of right valve consist of smooth anterior 
tooth, fiange-like posterior tooth, and crenulate median groove. Four oblong adductor 
muscle scars form vertical row in lower half of valve; elongate single frontal scar anterior 
to topmost adductor scar. 






Figure 20. Semicytherura quadraplana sp. nov. a, paratype, USNM 128106; internal view of adult right valve, 
b, holotype, USNM 128105; external left valve view of adult carapace, c, paratype, SDNH 04221; dorsal view of 
left valve, e, enlarged view of normal pore cluster as seen with transmitted light. 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



195 



289 


132 


137 


275 


133 


70 


276 


129 


73 


267 


129 


140 


276 


136 


137 


277 


133 


134 


269 


129 


134 



Dimensions. — Length Height Width 

Holotype, USNM 128105. Adult carapace, sta. B-6100 

Paratype, USNM 128106. Adult right valve, sta. B-6100 

Paratype, SDNH 04221. Adult left valve, sta. B-6100 

Paratype, SDNH 04222. Adult carapace, sta. B-6100 

Paratype, USNM 128107. Adult carapace, sta. B-6100 

Paratype, SDNH 04223. Adult carapace, sta. B-6100 

Paratype, SDNH 04224. Adult carapace, sta. B-6100 

Discussion. — The ridge arrangement of Semicytherura quadraplana is somewhat similar 
to that found on 5". quadrata (Hanai, 1957:20) from Japan, though these species differ in 
other aspects. The strongly developed alae set this new species apart from any known 
Semicytherura. The unique ridge arrangement is a result of the singular lateral ridge 
following each ala to the venter from anterior and posterior midheights. 

Family Hemicytheridae Puri, 1953 

Genus Mutihis Neviani, 1928 

Mutilus convergens clippertonensis subsp. nov. 

Figure 21, 22 

Aurila convergens Swain, 1967:79, pi. 8, fig. 8; Gunther, 1967:97, pi. 1, fig. 8. 

Diagnosis. — A species of Mutihis with highly arched dorsum, well developed poste- 
rodorsal tubercle, prominent ornamental ridge and furrow from posterodorsum to 
anteroventer across dorsolateral-anterolateral areas. 

Description. — In side view: margins rounded except at small pointed caudal process near 

400 



300 



I- 
I 
19 

UJ 

I 



200 



100 









VII 

• 


VIII 

• 

- r 

•• •• 






VI 
V 

L • 


• • • • 

V 




1 


• 

IV 

• 

• 


!•. 







100 



200 



300 



400 



500 



600 



LENGTH 



f 



Figure 21. Length-height plot of six growth stages of Mutilus convergens clippertonensis subsp. nov. from 
stations B-4241, B-6101, and B-6100. All measurements taken on complete carapaces or the larger left valves. 
Labeling of the instars assumes that the species has eight growth stages. 



196 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



posteroventer beneath slightly concave posterium; dorsum gently rounded, continuous with 
obliquely rounded anterior margin; ventral margin sinuous, slightly concave downward at 
inturned area; right valve somewhat larger than left valve, overreaching left valve along 
posterior, dorsum, and part of anterior margins; prominent angled posterodorsal tubercle at 
juncture of ornamental ridges. Ornamentation of six horizontally trending ridges with 
large reticulations in intermediate furrows; two parallel sinuous ridges extend from 
posteroventer to anteroventer; prominent ridge and furrow from posterodorsal tubercle to 
anteroventer via dorsolateral-anterolateral areas. In dorsal view: carapace lenticular, 
greatest width at midlength; anterior and posterior blunt. Eye tubercles small, on heavy 
marginal rim system. Males present but shell dimorphism not apparent. 

Duplicature about 50 /x wide, continuous along venter. Radial pore canals abundant, 

a 




Figure 22. Mutilus convergens clippertonensis subsp. nov. a-b, paratype, USNM 128109; a, externa! right valve 
view of adult carapace; b, dorsal view. c. holotype, USNM l2Si08; internal view of adult left valve, d, paratype, 
SDNH 04226; dorsal view of adull left valve, e, paratype, SDNH 04225; dorsal view of adult right valve, f, 1st 
antenna (incomplete), g, male 2nd antenna with long spineret bristle, h, female, 2nd antenna in part showing 
reduced spineret bristle, i, mandible and maxilla, j. 1st thoracic lee. 



ength 

558 


Height 
346 


Widt 
150 


550 


345 


296 


537 


316 


142 


542 


335 


150 


456 


281 


218 


380 


234 


183 


302 


195 


133 


242 


158 


103 



1971 ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 197 

evenly spaced, straight, unpaired, each with small midswelling; vestibules shallow. Normal 
pores large, sparse, sieve type. Hinge amphidont; anterior tooth of right valve stepped; 
posterior tooth of right valve bifed in ventral part; median bar and tooth of left valve 
smooth. Four adductor muscle scars, second scar from top distinctly divided into two equal 
smaller scars; oblique row of three mandibular scars located anterior to top two adductor 
scars; conspicuous oblong scar directly above adductor group in dorsal half of valve. 

Dimensions. — The dimensions of the adults, based on the analysis of 50 carapaces and 
larger left valves, are: L = 544.0 ± 19.2^1, H = 331.5 ± 18.8 ju; W = 264.0 ± 18.8 ^i. The 
arithmetic mean widths of the instars VII, VI, V, and IV are 215 i^l, 169 /i, 136ju., and 103 ju, 
respectively. Lengths and heights of the young are shown in figure 2 1 . 

Holotype, USNM 128108. Adult left valve, sta. B-6120 
Paratype, USNM 128109. Adult carapace, sta. B-6120 
Paratype, SDNH 04225. Adult right valve, sta. B-6120 
Paratype, SDNH 04226. Adult left valve, sta. B-6120 
Paratype, USNM 1281 10. 7th instar carapace, sta. B-6101 
Paratype, USNM 128111. 6th instar carapace, sta. B-6101 
Paratype, SDNH 04227. 5th instar carapace, sta. B-6100 
Paratype, SDNH 04228. 4th instar carapace, sta. B-6100 

Discussion. — Almost 1000 specimens were counted and examined. The species is by far 
the most abundant ostracode living in the shallow marine environments around Clipperton 
Island from shoreline to depths of 40-45 m. It is still relatively abundant at 92 m, however, 
this may be an artifact of redeposition as no living individuals were found at that depth. 
The few specimens from Sta. B-4244-47 were all dead and we assume that they may have 
lived there at a time prior to the enclosing and freshening of the inner lagoon. 

The Clipperton Island specimens are assigned to a species occurring in the Gulf of 
California (Swain, 1967) and the Gulf of Panama (Giinther, 1967). The most distinctive, 
and apparently unique, feature of the valve is an ornamental furrow running from the 
posterodorsum to the anteroventer; this is highly developed in the Clipperton Island 
subspecies. Mutilus convergens is closely related to M. palosensis LeRoy (1943) from 
California and the west coast of Baja California (Benson, 1959) and to the fossil Hawaiian 
Island M. oahuensis Holden (1967). This group is characterized by a well developed 
posterodorsal ridge juncture, a sinuous ventral margin paralleled by one or two ventrola- 
teral ridges, and a tendency for the lateral ridges to converge anteroventrally. All of these 
ornamental and morphological conditions are more prominently developed in the Clip- 
perton species than in any other. 

Family Limnocytheridae Klie, 1938 

Genus Limnocythere Brady, 1868 

Limnocythere viaticum sp. nov. 

Figure 23 

Diagnosis. — Carapace fragile, small, less than 400/1 long; lightly reticulate and punctate; 
reniform-shaped as seen in side view; large dorsolateral swelling in front of median sulcus, 
smaller swelling below, at center of valve; anterior wedge-shaped and sharply pointed as 
seen from above. 

Description. — In side view: shell reniform, ventral margin broadly concave, dorsal 
margin straight to slightly arched; anterior and posterior margins broadly rounded; surface 
of valves lightly reticulate in posterolateral and ventrolateral areas, lightly pitted in 



198 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



anterior and on swellings; large swelling above smaller one between two dorsolateral sulci; 
anteromost sulcus irregular, poorly developed; posteromost sulcus well developed, vertical; 
third dorsolateral swelling behind posteromost sulcus poorly developed; small fourth 
swelling on posterior part of ventrolateral inflation; left valve slightly larger, and 
overreaching right valve anteriorly and posteriorly. In dorsal view: greatest width in 
posterior half at ventrolateral swelling; posterior half of carapace inflated; anterior half 
wedged shaped, pointed. 

Duplicature narrow, traversed by sparse, evenly spaced radial pore canals, about 15 
posteriorly and anteriorly. Four oblong adductor scars in vertical row in ventral half of 
valve; single mandibular scar ventral and anterior to adductor group; single frontal scar 
anterior and dorsal to adductor group. Hinge weak, left valve with terminal depressions 
(sockets) near cardinal angles. 
Dimensions. — 

Holotype, USN M 128112. Adult carapace, sta. B-4244, 47 
Paratype, USNM 1281 13. Adult right valve, sta. B-4244, 47 
Paratype, SDNH 04229. Adult carapace, sta. B-4244, 47 
Paratype, SDNH 04230. Adult carapace, sta. B-4244, 47 
Paratype, SDNH 0423 1 . Adult carapace, sta. B-4244, 47 
Paratype, SDNH 04232. Adult right valve, sta. B-4244, 47 

Discussion. — Limnocythere viaticum is one of three freshwater species found in Clip- 
perton lagoon. The taxon cannot be identified with any known species, though the 



ength 


Height 


Width 


ill 


213 


184 


366 


203 


75 


358 


203 


166 


363 


212 


182 


375 


216 


179 


363 


216 


175 






Figure 23. Limnocvlhere viaticum sp. nov. a-b, holotype, USNM 1281 12; a, lateral right valve view of adult 
carapace: b, dorsal view of adult carapace, c, paratype, USNM 1281 13; interior view of adult right valve. 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



199 



freshwater ostracode faunas of Central America, where one might expect these to have 
originated, are very poorly known. 

As discussed elsewhere, the freshwater lagoon is a relatively recent phenomenon. The 
specific name alludes to the species, or its ancestors, trip to the island: viaticum (L.) 
"voyager." 



Family Paradoxostomatidae Brady and Norman, 1889 

Genus Paradoxostoma Fischer, 1855 

Paradoxostoma limbaughi sp. nov. 

Figure 24 

Diagnosis. — Elongate Paradoxostoma posteriorly terminating at midheight in blunt point; 
greatest carapace height in posterior half; dorsal view of carapace lenticular and symmetrical 
except for bluntly pointed anterior. 

Description. — Shell fragile, transparent; relatively small for genus, length about 340 ix. In 
side view: carapace elongate, length IVi times height; highest point of carapace just 
posterior to midlength at broadly arched dorsum; posterodorsal margin flattened; pos- 
terior margin bluntly pointed at midheight; ventral margin broadly concave downward at 
inturned area in anterior half, broadly rounded in posterior 2/3 of valve. In dorsal view: 

t 



a 




'S^-^'i^^i^^j^^S;^}^!^^'^ 





Figure 24. Paradoxostoma limbaughi sp. nov. a-b, holotype, USNM 1281 14; a, lateral right valve view of adult 
carapace: b, dorsal view of adult carapace, c. paratype, USNM 128! 15: interior view of adult right valve. 



ength 


Height 


Width 


341 


\11 


90 


328 


129 


50 


326 


134 


92 


334 


130 


87 


338 


135 


92 


340 


137 


93 



200 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

outline symmetrically lenticular except for bluntly pointed anterior; greatest width at 
midlength. Internal features not discernible. 

Dimensions. — 

Holotype, USNM 1281 14. Adult carapace, sta. B-4241 
Paratype, USNM 1281 15. Adult right valve, sta. B-4241 
Paratype, USNM 1281 16. Adult carapace, sta. B-4241 
Paratype, SDNH 04233. Adult carapace, sta. B-4241 
Paratype, SDNH 04234. Adult carapace, sta. B-4241 
Paratype, SDNH 04235. Adult carapace, sta. B-4241 

Discussion. — The species apparently belongs in the genus Paradoxostoma based on 
general morphology; however, it is possible that it could be placed in Xiphicilus which is 
usually more pointed at both ends, or Cytherois which is less bluntly pointed. 

The species is similar to Paradoxostoma artum Bold, 1966, from the Caribbean and 
Xiphicilus sp. cf. X. arenatus Brady from New Caledonia in the sense of Apostolescu, 
1967. 

The species is named for the late Conrad Limbaugh who helped collect the Clipperton 
Island samples. 

Genus Sclerochilus Sars, 1866 
Sclerochihis sp. 

Figure 25 

Sclerochilus contnrtus: Muller, 1894: 282, pi. 16. fig. 2. 
Sclerochilus sp. B. Holden, 1967: 39, text figs. 30a-c. 

Description. — In side view: shell reniform, with broadly and evenly arched dorsum: 
ventral margin sinuous, greatly rounded in posterior two-thirds, concave downward in 
anterior half; carapace relatively high, length/height ratio = 2.0, posterior bluntly pointed 
at midheight or broadly rounded. In dorsal view: carapace lenticular, compressed, length/ 
width ratio = 2.7; greatest width at midlength, posterior and anterior pointed. Dimorphism 
not observed. 

Duplicature wide; vestibules large; fused zone narrow, with continuous width of about 
15 /.I. Radial pore canals simple, numbering 20 to 30 throughout duplicature. Normal pores 
open, small, sparse. Five adductor muscle scars in oblong oblique pattern at midheight of 
valve just anterior to midlength. 

Dimensions. — 

Specimen, USNM 128079. Adult right valve, sta. B-6I20 
Specimen, USN M 1 28080. Adult left valve, sta. B-6 1 20 
Specimen, SDNH 04236. Adult left valve, sta. B-6120 
Specimen, SDNH 04237. Adult right valve, sta. B-6120 
Specimen, SDNH 04238. Penultimate carapace, sta. B-6120 

Discussion. — These specimens are identical to Sclerochilus sp. B (Holden, 1967) from late 
Cenozoic drowned terraces in the Hawaiian Islands, and to a form from the Mediterranean 
identified by Muller (1894) as S. contortus (Norman). Muller's illustrations (pi. 16, figs. 
1-2) of this form show distinct sexual dimorphism, the males being the lower and relatively 
more elongate of the two. Sclerochilus sp. is similar to the female, illustrated by Muller, 
but not to the male. These specimens, including Muller's are considered distinct from 5". 
contortus (a North Atlantic species) based on difTerences in the morphology of the shell. 
Whether only females have been found at Clipperton Island or whether the population 



ength 


Height 


Width 


421 


210 


71 


408 


208 


73 


383 


190 


75 


398 


193 


65 


350 


176 


135 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



201 



there shows no sexual dimorphism is unknown. Unfortunately the soft parts were not 
preserved. 





■^'t^.x 



:-x>s 



^:^ 



^:^ 



'■^k 



H 



Figure 25. Sclerochilus sp. a-c, specimen, USNM 128079; a, lateral view of adult right valve; b, dorsal view of 
adult right valve; c, interior view of adult riaht valve. 



Family Trachyleberididae Sylvester-Bradley, 1948 

Genus Neocaudites Purl, 1960 

Neocaudites pacifica paciHca sp. nov. 

Figure 26 

Diagnosis. — Moderate size Neocaudites. length to 559 /-i, ornamented with larged shallow 
reticulations; distinctive, isolated, denticulate, submarginal ridge, paralleling anterior 
margin; valves asymmetric with dorsal and lateral ridge juncture at posterodorsum more 
posteriorly extended in right than left valve. Frontal scar v-shaped, three adductor scars. 

Description. — In side view: carapace subquadrate. dorsal margin irregular to straight, 
subparallel with gently concave ventral margin: anterior margin broadly rounded, finely 
and evenly denticulate in ventral half; posterior subtruncate. with low, bluntly pointed, 
caudal process; left valve overlapping right valve at postero- and anterocardinal angles. 
Ornamentation of large shallow reticulations; marginal rim continuous from anterocar- 
dinal angle around anterior, along venter, around posterior; lateral field with smooth, 
straight centrolateral ridge extending from posterodorsal area to low, inconspicuous 
subcentral tubercle; prominent, narrow submarginal ridge in anterolateral area, paral- 



202 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

leling anterior margin; broad, shallow vertical sulcus anterior to midlength; eye tubercles 
small, prominent. In dorsal view: carapace compressed, width/length ratio =0.30, 
carapace of equal width from subcentral region to posterocardinal region; caudal and 
anterior parts compressed; valves asymmetric: right valve with more posteriorly extended 
ridge juncture. 

Duplicature moderately broad, shallow vestibule irregularly shaped. Radial pores 
sometimes branched, commonly with midswellings, about 30 in anterior, 25-30 in 
posterior. Normal pores small, sieve type. Hinge holamphidont; left valve with entire, 
projecting, stepped anterior tooth; entire reniform posterior tooth. Smooth median bar of 
left valve with low, smooth anterior tooth. Three oblong adductor muscle scars on 
posterior side of subcentral depression; bottom-most scar apparently a fused pair. Large 
V-shaped frontal scar anterior to top-most adductor scar on side of subcentral depression. 
Single circular mandibular scar beneath frontal scar. 

Dimensions. — Length Height Width 

Holotype, USNM 128117. Adult right valve, sta. B-6120 524 260 75 

Holotype, USNM 128117. Adult left valve, sta. B-6120 524 270 89 

Paratype, SDNH 04239. Adult right valve, sta. B-6120 523 253 81 

Paratype, SDNH 04239. Adult left valve, sta. B-6120 533 266 92 

Paratype, SDNH 04240. Adult carapace, sta. B-8558 600 318 184 

Paratype, USNM 128118. Adult carapace, sta. B-8558 508 312 191 

Paratype, USNM 128119. Adult carapace, sta. B-8558 559 302 175 

Paratype, SDNH 04241. 6th instar, sta. B-6120 414 224 141 

Paratype, SDNH 04242. 5th instar, sta. B-6120 350 183 146 

Neocaudites paciflca minima subsp. nov. 

Figure 26 

Diagnosis. — Small, length about 450 i-i, ornamented with various sized reticulations and 
pits; small, isolated, denticulate, submarginal ridge paralleling anterior margin; valves 
asymmetric with dorsal and lateral ridge juncture at posterodorsum more posteriorly 
extended in right valve; frontal scar s-shaped, four adductor scars. 

Description. — Except for the differences stated in the diagnosis above, all other morpholo- 
gical details of N. pacifica pacifica are the same as those of this subspecies. 

Dimensions. — Length Height Width 
Paratype, USNM 128120. Adult carapace, Hanauma Bay, 

Hawaiian Islands 424 

Paratype, SDNH 04243. Adult left valve, Hanauma Bay 458 

Paratype, SDNH 04243. Adult right valve, Hanauma Bay 458 

Discussion. — Neocaudites pacifica minima from Hanauma Bay, Oahu, Hawaii, is 
believed to be subspecifically related to A', pacifica pacifica from Clipperton Island and is 
diagnosed here for comparative purposes. The most apparent ditTerence between the two is 
that of size. A', pacifica minima being much smaller (length 450 jx) than that of N . pacifica 
pacifica (length = 525 /x). The Clipperton Island form occurs in deeper waters than the 
Hawaiian Island form (10 m). At Clipperton, it was collected alive at locality B-6120 
(40^5 meters) and dead at locality B-8558 (92 meters). 

The genus Neocaudites has been characterized as a Caribbean taxon (McKenzie, 
1967: 232). Previously, only one species had been reported from the Pacific basin, N. terryi 
from off the Hawaiian Islands on submarine terraces. Although N. terryi is generally 



217 


144 


216 


100 


209 


95 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



203 



similar to N. pacifica. its surface ornamentation is smooth rather than reticulate or pitted. 

a 




Figure 26. S'eocaudites pacifica sp. nov. a-c, holotype, USNM 128 117; a, external right valve view of adult 
male carapace; b, dorsal view; c, internal view of right valve, d-e, paratype, SDNH 04239; d, dorsal view of adult 
male left valve; e. dorsal view of right valve, \eocaudites pacifica minima subsp. nov. f, holotype, USNM 
128120; external right valve view of adult female carapace; g-i. paratype, SDNH 04243; g, internal view of adult 
male left valve; h. dorsal view of left valve; i, dorsal view of right valve. 

Genus Occultocythereis Howe, 1951 
Occultocythereis angusta Bold, 1963 

Figure 27 

Cythereis deformis Brady, 19 II: 397, pi. 20, figs. 7-8; not Cythereis deformis Baird, 1850: 256, pi. 18. figs. 4-6. 
Occultocythereis angusta Bold, 1963: 391, pi. 9, tigs, la-c, pi. 12. fig. 6 new name for Cythereis deformis Brady. 

Diagnosis. — Occultocythereis with posterodorsal tubercle and posteroventral marginal 
rim heavy: dorsal rim weakly developed; lateral surface ornamentation very weakly 
developed; dorsal margin concave as seen from the side. 



204 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Description. — In side view: carapace small, length 450 ^i; length/height ratio =2.0; highest 
point at anterocardinal angle in anterior third at midlength; dorsal margin straight 
between elevated cardinal angles; ventral margin straight or slightly irregular; anterior 
margin evenly and broadly rounded, with several well-developed denticles; larger left valve 
over-reaching right valve along venter, posterior, and at anterocardinal hinge angle; left 
valve asymmetric with elongate flange extending beneath valve along posteroventer 
margin; broad, flattened anterior marginal rim continuous from poorly developed eye 
tubercle to ventral inturned area; posteroventral area with complex massive tubercles; 
posterocardinal angle occupied by large dimpled tubercle; valves conspicuously sulcate at 
midlength; surfaces generally smooth between narrow, inconspicuous, serpentine ridges in 
lateral areas. In dorsal view: greatest width in posterior third at ridge juncture terminating 
in small, posteriorly pointing, lateral spine, anterior bluntly pointed due to thick antero- 
marginal rim; posterior compressed behind posterocardinal tubercles. 






Figure 27. Occultocythereis angusla Bold, 1963. a-d, hypotype. USNM 128081; a. lateral right valve view of 
carapace; b, dorsal view of adult left valve; c, dorsal view of adult right valve; d, adductor muscle scar pattern of 
left valve. 

Duplicature of moderate width; vestibulae well developed, line of concrescence 
irregular and forming pockets into fused zone from which emanate straight, simple, 
abundant radial pore canals, about 30 in anterior; normal pores large, sparse, sieve type. 
Muscle scar pattern as shown in Figure 27d. 

Dimensions. — Length Height Width 

Hypotype, USNM 128081. Adult carapace, sta. B-6120 461 229 183 

Discussion. — Occultocythereis angusta is distinctive by the combination of features noted 
in the diagnosis. The dorsal ridce and lateral surface ornamentation is subdued, like that of 



1971 ALLISON AND HOLDENiCLIPPERTONOSTRACODA 205 

O. lineata (Miiller, 1894) from the Mediterranean, in contrast to many of the early Tertiary 
species (Hinte, 1964; Triebel, 1961; Howe and Law, 1936; etc.). These two Recent species 
differ, O. angusta being smaller, relatively longer, and having a concave upward dorsal 
margin instead of a slightly convex one as shown by Muller ( 1 894, pi. 29, fig. 2 1 ). 

The Clipperton Island specimens more closely resemble the Caribbean form of O. 
angusta illustrated by Bold (1963b, pi. 9, fig. 1) and Teeter (1966, pi. 6, figs. 20-21) than 
the recent form from Madeira (Brady, 191 1, pi. 20, figs. 7 8); however, the dissimilarities 
are slight and they appear to be conspecific. 

Genus Xestolebris Sars, 1 866 
Xestoleberis gracilis Brady, 1890 

Figure 28 

Xestoleberis gracilis Brady, 1890: 508. pi. 3, figs. 9-10. 

Diagnosis. — A dorsoventrally compressed species o{ Xestoleberis with a broadly rounded 
dorsal margin and straight flat venter. 

Description. — In side view: males similar in profile to females; carapace low, dorsoven- 
trally compressed, length/height ratio =2.5; ventral margin straight, flat; dorsal margin 
evenly and broadly rounded; anterior margin low, sharply rounded but not pointed; surface 
of valves smooth. In dorsal view: males lenticular, greatest width near midlength; females 
posteriorly inflated, greatest width in posterior quarter. 

Posterior duplicature narrow; anterior duplicature of moderate width with narrow 
fused zone containing few (10 to 12) simple, straight, radial pore canals concentrated in 
ventral part. Normal pores large, especially abundant in anteroventer. Hinge typical for 
genus, terminal elements of right valve projecting crenulate plates, about 30 /x in length, 
separated by a smooth arcuate groove. Four large, oblong adductor scars in oblique row in 
anterior half at shell midheight; two frontal scars, one an arcuate bar, the other a spot 
anterodorsal to it, directly in front of top two adductor scars. Wide, arcuate, highly 
inclined, xestoleberid scar directly above adductor group near dorsum. 

Dimensions. — 

Hypotype, USNM 128082. Adult carapace, sta. B-6101 
Hypotype, USNM 128083. Adult carapace, sta. B-6120 
Hypotype, SDNH 04245. Adult left valve, sta. B-4241 
Hypotype, SDNH 04246. Adult right valve, sta. B-4241 
Hypotype, SDNH 04246. Adult left valve, sta. B-4241 
Hypotype, SDNH 04247. Penultimate carapace, sta. B-4241 
Hypotype, USNM 128084. Penultimate carapace, sta. B-4241 

Discussion. — The species was originally described from Samoa living on reefs and 
intertidal pools (Brady, 1890). At Clipperton it is most common on the reef flat but one 
living specimen was found at 10 12 meters on the submerged terrace. 

The species is somewhat similar to Xestoleberis humilis Klie, 1940, living in the 
"algalzone" along the west coast of Africa. 

Xestoleberis sp. aff. X. eulitoralis Hartmann, 1959 

Figure 29 

Xestoleberis eulitoralis Hdrim-dnn. 1959b: 224, pi. 42, figs. 134-136: pi. 43, figs. 137, 138, 140. 141. 
Xestoleberis cf. .X. eulitoralis: McKenzie and Swain. 1967: 303. te.xt fig. 34. 

Description. — Carapace moderately compressed, surface of valves smooth; sexual di- 



ength 


Height 


Width 


316 


132 


187 


307 


126 


162 


308 


129 


123 


309 


138 


84 


324 


151 


93 


249 


125 


146 


260 


126 


151 



206 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




ioo/< 



Figure 28. Xestoleheris i^racilis Brady, 1890. a-b, hypotype, USNM 128082; a, left valve view of adult female 
carapace; b, dorsal view of adult female carapace, c-e, hypotype, USNM 128083; c, left valve view of adult male 
carapace; d, dorsal view of adult male carapace; e, anterior view of adult male carapace, f-h, hypotype, SDNH 
04245; f, interior view of adult female right valve; g, dorsal view of adult female left valve; h, dorsal view of adult 
female right valve. 

morphism not observed. In side view: valves suboblong, broadly rounded in outline, dorsal 
margin sloping slightly anteriorly; ventral margin straight; anterior and posterior margins 
bluntly rounded; carapace moderately compressed laterally, greatest inflation in ventral 
third; surfaces smooth. In dorsal view; carapace oblong, anterior and posterior bluntly 
rounded; greatest width at midlength. 

Posterior duplicature narrow, entirely fused; anterior duplicature of moderate width, 
vestibulatc. Radial pore canals simple, straight, equally spaced, numbering 20 in anterior, 
about 20 in posterior. Hinge typical for genus: smooth median bar of left valve almost 
straight as seen from above. Adductor muscle scar pattern a small vertical row of four 
elongate scars; single frontal scar directly anterior to topmost adductor scar. 



1971 



ALLISON AND HOLDLN; CLIPPERTON OSTRACODA 



207 



Dimensions. — Length Height Width 

Specimen, USNM 128085. Adult left valve, sta. B-6 120 302 164 86 

Specimen, SDNH 04244. Adult carapace, sta. B-6120 305 169 1 14 

Specimen, USNM 128086. Adult left valve, sta. B-6120 300 164 82 

Discussion. — The Clipperton Island specimens resemble Xestoleberis sp. cf. X. eulitoralis 
from Scammons Lagoon, Baja California, Mexico, more than they do the species from El 
Salvador which has no vestibule and has relatively complex radial pore canals. More and 
better preserved material would probably show this species to be conspecific to at least 
those from Scammons Lagoon. 

At El Salvador Xestoleberis eulitoralis was found in the intertidal zone of Mejanguera 
Island, Gulf of Fonseca among rocks with corals, encrusting algae, barnacles, and oysters. 
McKenzie and Swain report their species occurring throughout Scammons Lagoon from 4 
to 75 feet. At Clipperton Island three disarticulated valves were found at B-6120 (40^5 
meters) and one at B-8558 (92 meters). 







,i:Usfeu%yi^!i-kJ»^5-=-^ 



lOO 



^ 




Figure 29. Xestoleberis sp. alT. X. eulitoralis Hartmann, 1959. a-d, specimen, USNM 128085; a, dorsal view of 
adult left valve; b, anterior view of adult left valve; c, lateral view of adult left valve; d, interior view of adult left 
valve. 

Genus Uncertain 
"Cy there" cf. "C." caudata Brady, 1890 

Figure 30 

Description. — In side view: carapace elongate, length/height ratio = 2.5; dorsal margin 
parallel to ventral margin throughout most of length; anterior margin broadly rounded; 
posterior with large compressed, bluntly pointed caudal process most of which lies beneath 
midheight. Shell ornamented with about 10 continuous and discontinuous glassy horizon- 



208 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



tal ridges tending to parallel anterior margin. Caudal process and adjoining compressed 
parts of carapace smooth. In dorsal view: anterior sharply pointed; carapace midhalf 
parallel sided; posterior convex to highly compressed; caudal process of extreme posterior. 
Internal features not observed. 





Figure 30. "Cythere" sp. cf. "C" caudata Brady, 1890. a-b, specimen, USNM 128087; a, right valve view of 
adult(?) carapace; b, dorsal view. 

Dimensions. — Length Height Width 

Specimen, USNM 128087. Entire specimen, sta. 8558 540 230 180 

Discussion. — Only one specimen was collected by the carrousel dredge at 92 m. The 
species closely resembles Cythere caudata Brady, 1890 from Sava, Sava Bay, Fiji, and 
"Cythere" caudata from Manila (Keij, 1954) and Hawaii (Holden, 1967). The single entire 
carapace from Clipperton Island is larger than those mentioned above. Brady's and Keij's 
species are 460 /x and 450 /x respectively. The ones from Hawaii come from two 
populations, one fossil with an individual 410 ;u. in length and one from Hanauma Bay with 
very small adult individuals only 350 ii long. The Clipperton Island form is distinctive with 
well developed horizontal ridge ornamentation, the elongate reticulae characteristic of the 
other related forms being defined between ridges. At the present time it is not possible to 
determine the specific relationships between the Clipperton forms and those described by 
other authors. All of the above species belong to an undescribed genus. 



Suborder Platycopina Sars, 1866 

Family Cytherelloidea Sars, 1866 

Genus Cytherelloidea Alexander, 1929 



1971 



ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 



209 



Cytherelloidea praecipua Bold, 1963 
Figure 31 

Cytherelloidea praecipua van den Bold, 1963: 75, pi. 1, tigs. 1-7. 

Diagnosis. — Carapace reticulate, becoming smooth centrally; valves with poorly devel- 
oped horizontal ridges; left valve with strong dorsal tooth fitting into large socket of right 
valve; large dorsal flange of right valve overlapping left valve at midlength. 

Description. — In side view: carapace subquadrate; dorsal margin slightly rounded, 
somewhat irregular centrally at articulation; posterior margin truncate, anterior margin 
broadly rounded. Surfaces reticulate except in middle of valves where ornamentation is 
reduced to small pits or absent; reticulation pattern parallel to anterior margin becoming 













Figure 31. Cytherelloidea praecipua Bold, 1963. a-g, hypotype, USNM 128088; a, left valve view oF adult 
female carapace; b, right valve view of adult female carapace; c, dorsal view of adult female carapace; d, dorsal 
view of adult female left valve; e, dorsal view of adult female right valve; f, interior view of adult female left valve; 
g, interior view of adult female right valve. 



210 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

pronounced and deep behind strong anterior rim in left valve; broad undulating sulci in 
dorsolateral and posterolateral areas, resulting in three ridge-like swellings along dorsum, 
venter, and from posterior cardinal angle to center of valve beneath prominent circular 
dorsocentral depression corresponding to internal adductor muscle scar swelling. Two 
circular swellings in posterior quarter of female carapace. Right valve larger, overlapping 
left valve around all margins. In dorsal view: female carapace lanceolate with greatest 
width at truncate posterior; right valve strongly overlapping left valve just anterior to 
midlength with large flange-like external tooth. 

Anterior duplicature broad for genus, about 40 /j. at widest point, fused; 15-18 evenly 
spaced, simple, anterior radial pore canals passing through marginal denticles. Hinge of 
left valve with large flattened tooth just posterior to midlength; right valve with corre- 
sponding "socket." About 1 1 oblong adductor muscle scars in typical Cytherelloidea 
pattern on broad swelling in dorsal half of carapace at midlength. 

Dimensions. — The collection consists of eight adult specimens of which six were entire. 
Lengths range from 522 to 550 /x with an average of 535 /x; heights range from 297 to 3 14 ju, 
with an average of 308 ju,; widths range from 1 89 to 228 /x with an average of 2 1 1 p.. 

Hypotype USNM 128088. Adult left valve, sta. B-6120 
Hypotype, USNM 128088. Adult right valve, sta. B-6120 
Hypotype, SDNH 04248. Adult carapace, sta. B-6120 
Hypotype, SDNH 04249. Adult carapace, sta. B-6120 
Hypotype, SDNH 04250. Adult carapace, sta. B-6120 
Hypotype, SDNH 04251. Penultimate carapace, sta. B-6120 
Hypotype, SDNH 04252. Penultimate carapace, sta. B-6120 
Hypotype, SDNH 04253. Penultimate carapace, sta. B-6120 

Discussion. — Small difl'erences can be noted between the Clipperton Island forms of 
Cytherelloidea praecipua and those described by Bold (1963) from Tobago and Trinidad. 
Bold's illustrations of the species show a more arched dorsum and concave downward 
venter. In addition, the left valve hinge tooth appears smaller. In all other aspects the 
Clipperton Island forms seem identical to those from the Caribbean. 

ACKNOWLEDGEMENTS 

We would like to thank W. A. van den Bold, Louisiana State University, for information concerning the 
relationship of our fauna to those of middle America, and J. Teeter, University of Akron, who made unpublished 
information available. Arnold Ross and J. R. Jehl, Jr., San Diego Natural History Museum, read the final 
manuscript and offered many helpful suggestions. The laboratory work and manuscript preparation, largely 
completed at San Diego State College during the summer of 1968, have received partial support from the 
National Science Foundation through Grant GA-1403. This paper is a contribution from the Scripps Institution 
of Oceanography, University of California, San Diego, California. 

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ength 


Height 


Width 


538 


300 


189 


538 


304 


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540 


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215 


533 


297 


209 


550 


313 


228 


477 


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156 


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484 


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158 



1971 ALLISON AND HOLDEN: CLIPPERTON OSTRACODA 21 1 

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Department of Geology, San Diego State College, San Diego, California 921 15, and 
National Oceanic and Atmospheric Administration, Atlantic Oceanographic and Mete- 
orological Laboratories, 901 South Miami Avenue. Miami. Florida 33130 




j-^^J MUS. COMP. ZOOL. 

LIBRARY 

JUN 41971 

HARVARD 
UNIVERSITY 



STUDIES ON THE TETRACLITIDAE 

(CIRRIPEDIA: THORACICA) 

A NEW TETRACLITELLAN FROM INDIA 



ARNOLD ROSS 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 



VOL. 16, NO. 8 21 MAY 1971 



STUDIES ON THE TETRACLITIDAE 

(CIRRIPEDIA: THORACICA) 

A NEW TETRACLITELLAN FROM INDIA 



ARNOLD ROSS 



ABSTRACT — Tetraclitella contains eight species, including T. karandei n. sp. from Mad'h Island, India, 
all of which are restricted largely to the Indo-West Pacific faunal province. Two groups may be recognized in 
this genus on the basis of opercular morphology. One species in each of these groups has radii that are 
elevated well above the surface of the parietes. In T. danvini the elevated radii serve to strengthen the shell in 
the absence of sutural ridges and denticulae; in T. karandei they probably create water turbulence and thus 
enhance the fishing capabilities of the cirral net. 

Tetraclitella comprises eight, relatively small, patelliform, balanomorph barnacles 
that occupy habitats low in the intertidal zone. They are confined largely to the Indo-West 
Pacific faunal province, contrary to the statement by Utinomi (1970: 349) that they are 
"mostly circumtropical." All of the species occur predominantly on continental islands but 
there are a few scattered mainland records. Exceptions to this distribution pattern are T. 
purpurascens, which ranges from Australia to India, and T. divisa which is the only species 
that occurs circumtropically (Ross, 1968: 14). 

The barnacle fauna of India and adjacent areas is relatively well known through the 
work of Annandale, Nilsson-Cantell, Karande (1966) and several contemporary Indian 
workers. Therefore, it is surprising to note the presence of a new tetraclitellan from Mad'h 
Island on the Bombay coast of India (Fig. 1). This new species is similar in many ways to 
the widely occurring T. purpurascens, and records for that species should be reevaluated in 
the light of the present discovery. 

Dr. A. A. Karande, who collected the specimens reported on here, informed me that it 
occurs on the under surface of rocks, low in the intertidal zone, where it normally remains 
moist during periods of low tide. The shells commonly are covered with a dense mat of 
brownish-green, finely particulate, organic matter. The associated animals include the 
ubiquitous Planaxis sulcatus Born and a species of Acmaea. The ecological conditions 
under which this species lives and the few animals with which it is associated do not differ 
appreciably from those of other species of Tetraclitella. 

Family Tetraclitidae Gruvel, 1903 

Genus Tetraclitella Hiro, 1939 

Definition. — Shell generally less than 20 mm in rostro-carinal diameter, patelliform, 
ribbed; compartments discrete; parietes with 2 or more rows of tubes; radii broad, flush 
with or raised above parietal surface, summits horizontal, tubiferous, lacking teeth or 
denticles on articular surface; alae non-tubiferous; basis membranous, calcareous 
peripherally or wholly calcareous; scutum transversely elongated or higher than wide, 
commonly ornamented externally, lacking crests for depresser muscles; mandible with 5 
teeth and spine-like lower angle; maxilla I with 6-8 major spines below subapical notch. 



SAN DIEGO SOC. NAT. HIST., TRANS. 16 (8): 215-224, 21 MAY 1971 



216 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 1 . Map showing position of Mad'h Island relative to other islands along the Bombay coast of India. 



1971 ROSS: STUDIES ON THE TETRACLITIDAE 217 

Type species. — Lepas purpurascens Wood (1815: 55), Recent, Australia, by original 
designation of Hiro ( 1 939: 273). 

Remarks. — Hiro (1939: 273) established Tetraclitella as a subgenus of Tetraclita. 
Recently, in reevaluating the tetraclitids I raised the subfamily to familial status (Ross, 
1968: 6), and accordingly the subgenera of Tetraclita were raised to genera to better retlect 
relationships within the family (Ross, 1969: 237; Ross, 1970: 3). Utinomi (1970: 349) 
independently also accorded Tetraclitella generic rank. 

Species referable to Tetraclitella include: T. purpurascens (Wood, 1815: 55), T. 
costata (Darwin, 1854: 339), T. chinensis (Nilsson-Cantell, 1921: 359), T. divisa (Nilsson- 
Cantell, 1921: 362), T. darwini (Pilsbry, 1928: 314), T. multicostata (Nilsson-Cantell, 
1930: 2) and T. pilsbryi (Utinomi, 1962: 234). Tetraclita squamosa depressa (Kolosvary, 
1941: 42) from southern Australia, Tetraclita purpurascens darwini {Kolosvary, 1942: 140) 
from Port Jackson, New South Wales, Australia, and Tetraclita radiata wagneri (Kolos- 
vary, in Kolosvary and Wagner, 1941: 11) from Tasmania, on the basis of morphology and 
biogeography, are apparently conspecific with T. purpurascens purpurascens. 

KEY JOTHESPECIESOF TETRACLITELLA 
1. Radii elevated above surface of parietes 2 

1 . Radii flush with or sunken below surface of parietes 3 

2. Scutum higher than wide; intermediate segments of cirrus 

VI with 4 pairs of setae (Japan, Formosa) T. darwini 

2. Scutum wider than high; intermediate segments of cirrus 

VI with 3 pairs of setae (India) T. karandei 

3. Scutum higher than wide 4 

3. Scutum wider than high 5 

4. Scutum with a row of small longitudinal pits; intermediate 
segments of cirrus VI with 4 pairs of setae; basis calcareous 

(Lesser Sunda Islands, Sulu and Philippine Archipelagos) T. costata 

4. Scutum with 5 rows of longitudinal pits; intermediate segments of 

cirrus VI with 3 pairs of setae; basis membranous (Japan) T. pilsbryi 

5. Tergal spur essentially confluent with scutal margin 6 

5. Tergal spur well separated from scutal margin (intermediate 

segments of cirrus VI with 3 pairs of setae; circumtropical) T. divisa 

6. Parietal plates without hollows 7 

6. Parietal plates pierced by hollows (intermediate segments or 

cirrus VI with 4, rarely 3 pairs of setae; southern China, 

Formosa, Japan) T. chinensis 

1. Shell with 14 or fewer primary longitudinal ribs; cuticle 

persistent (West Irian, New Guinea) T. multicostata 

1 . Shell with 20 or more primary longitudinal ribs; cuticle not 

persistent (intermediate segments of cirrus VI with 2 pairs of setae; 

New Zealand, Tasmania, Australia, Malay Archipelago, India) . . T. purpurascens 



Tetraclitella karandei n. sp. 

Diagnosis. — Radii transversely ridged, the apical 3-4 ridges extending like fingers out 
and over adjoining plate; scutum transversely elongated, externally ornamented with 
prominent nodes where longitudinal ridges cross growth lines; intermediate articles of 
posterior cirri armed with 3 pairs of setae. 



218 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Description. — Shell white or grayish white, patelliform, ovate in outline, covered with 
persistent, hirsute, chitinous cuticle; parietes ornamented with prominent growth ridges, 
and high, primary, longitudinal ribs intercalated with lower secondary and tertiary ribs; 
ribs square or T-shaped in section, extending from orifice to or beyond basal edge of shell, 
occasionally bifurcate basally (Fig. 2a, b); orifice diamond-shaped; radii broad, horizon- 
tally ridged from base to apex, the ridges becoming progressively higher, produced and free 
from the surface (Fig. 2a); articular margin and finger like projections tubiferous, the 
apertural margins of the tubes being crenate; on the adjoining plate a narrow, longitudinal 
ridge occurs on parietal surface where the radius butts against the plate (Fig. 2b); alae 
broad, summits horizontal and crenate; sheath less than '/2 height of wall, basal margin not 
depending; basis calcareous peripherally. 

Scutum wider than high; external surface deeply sulcate (Fig. 2e); where the growth 
ridges are crossed by longitudinal ridges prominent nodes are formed thus rendering a 
scabrous appearance; articular ridge straight, about 2/3 length of tergal margin; adductor 
ridge low, not undercut, apically fused with articular ridge, terminating basally at basi- 
occludent angle; adductor muscle depression ovate, shallow, borders poorly delimited; 
depression for lateral depressor muscle shallow, poorly defined; depression for rostral de- 
pressor muscle lacking; apical portion of plate with weak ridges (Fig. 2d). 

Tergum higher than wide; external longitudinal furrow open, broad, shallow, extend- 
ing to base of spur; spur evenly rounded basally, confluent with scutul margin, width about 
'/2 that of basal margin (Fig. 2g); articular ridge inclined; articular furrow wide and 
shallow; 6-7 crests for depressor muscle, low, short, inclined; apical portion of valve ridged 
or roughened (Fig. 20- 

Measurements of the holotype are as follows (in mm): rostro-carinal diameter 10.1; 
height 3.5; rostro-carinal diameter of orifice 3.6; height of scutum 1.5; width of scutum 2.1; 
height of tergum 1.5; width of tergum 1.0. The mean rostro-carinal diameter of five 
paratypes is 13.5 mm and the height is 3.8 mm. 

Labrum with shallow, broad, medial depression; crest thick, heavily chitinized,armed 
with short, fine bristles but rarely with teeth (Fig. 3a). Palps long, broad, distal end broadly 
rounded; superior margin straight, basal margin convex; proximal setae on superior 
margin short, stout, coarsely bipectinate; distal setae on margin long, slender, finely 
bipinnate; basal portion of lateral surface covered with ctenae. Mandible with 5 unequally 
spaced teeth; teeth 2 and 3 commonly with 1-2 subsidiary cusps; tooth 4 with 3-5 subsidiary 
cusps; comb between tooth 5 and inferior angle containing 8-12 teeth; inferior angle 
commonly with 1 long, slender and 1 short, stout tooth (Fig. 4). Maxilla I with 2 long, stout 
and 1-2 shorter spines above sub-apical notch; 2-3 short, slender spines in notch; 6-8 stout 
spines medially; 8-12 short, slender spines in basal cluster (Fig. 3c). Maxilla II bilobate; 
setae along apical margin long; bipinnate, setae becoming progressively shorter toward the 
notch; setae on basal lobe coarse, bipectinate. 

Posterior ramus of cirrus I about 3/5 length of anterior ramus; intermediate articles 
of both rami broader than high; segments of anterior ramus normal, but those of posterior 
ramus protuberant; distal articles of both rami clothed with finely bipinnate setae (Fig. 3g). 
Rami of cirrus II essentially equal in length, and slightly longer than posterior ramus of 
cirrus I; medial segments of both rami protuberant; distal two segments of both rami 
armed with bipectinate setae, proximal segments with bipinnate setae (Fig. 3h). Rami of 
cirrus III of equal length, and same length as rami of cirrus II; medial segments of both 
rami protuberant; distal 2 or 3 segments of anterior ramus and all segments of posterior 
ramus armed with bipectinate setae (Fig. 3i). Cirri IV-VI essentially equal in length with 
equal rami; 1-2 stout spines and 2-3 long, slender setae at each articulation along greater 



1971 



ROSS: STUDIES ON THE TETRACLITIDAE 



219 







M 



i^ / 



^A -^ 



^-^ 











LJ 






■?.' 











f 




Figure 2. Shell and opercular plates of Tetraclitella karandei n. sp. a, apertural view of shell, x6; alar margin of 
lateral compartment, x7; c, basal view of carina, x8: d, e, internal and external views, respectively, of scutum, x30; 
f, g, internal and external views, respectively, of tergum, x30. Holotype (4000), a, c-g; paratype (400 1/c), b. 



220 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 








c 


0.05mm 


e 


0,01 


f 0,2 5 


ad 
gh i 


0,1 
0,25 




Figure 3. Trophi and cirri of Tetraclitella karandei n. sp. a, iabrum and palp; b, enlarged view of labrum; c, 
maxilla 1; d, maxilla II; e, intermediate segments of outer ramus of cirrus VI; f, penis; g, cirrus I; h, cirrus II; i, 
cirrus III. Holotype (4000), c, f; paratypes, a-b, d-e, g-i (a, d = 4001/c;b = 400i/d;e, g-i = 4001/b). 



1971 ROSS: STUDIES ON THE TETRACLITIDAE 221 

curvature of intermediate segments; 1 or 2 rows of ctenae present on lateral face of 
intermediate segments immediately below articulation; setation ctenopod, with 3 pairs of 
setae on each intermediate segment, and commonly a single proximal, short seta; at base of 
and between each major pair of setae there is a cluster of 3-5 short, slender setae (Fig. 3e). 
Cirral counts for specimens in the type lot are summarized in Table 1 . 

Table 1. Summary of data on cirral counts: range (R) and mean (X) value for number of segments in anterior 
(a) and posterior (p) rami 





I 






II 






III 




IV 




V 




VI 




a 


P 


a 




P 


a 




P 


a p 


a 




P 


a p 


N 


10 


10 


12 




12 


11 




11 


7 7 


6 




6 


4 4 


R 


lO-U 


6-7 


7-8 




6-8 


6-8 




6-9 


11-14 11-15 


14-16 




15-17 


15-16 15-18 


X 


10.6 


6.3 


7.3 




7.1 


7.1 




6.2 


12.8 14.0 


15.0 




15.2 


15.5 16.7 



Intromittent organ annulated throughout its length, and sparsely covered with short, 
slender bristles; distal extremity with 4 clusters of 1 1-14 setules (Fig. 30- 

Remarks. — Of the presently recognized tetraclitellans, T. karandei may be distin- 
guished by its radii, which have raised digitiform processes that extend out and over the 
adjoining plates. The shape of the tergum in karandei is similar to that found in 
multicostata, purpurascens and chinensis, but the scutum of this species has a scabrous or 
nodose ornamentation externally rather than only simple growth ridges. The mandible 
of karandei appears to be more variable than any other species in the degree of development 
and number of subsidiary cusps on the second, third, and fourth teeth (see Fig. 4). The 
crest of the labrum is commonly devoid of teeth as it is in purpurascens, costata and 
darwini. But when teeth are developed, they appear as simple, low, rounded knobs, that 
are few in number. The mouth parts and appendages have not been described for pilsbryi. 

Disposition of types. — The holotype and four paratypes are housed in the collections 
of the San Diego Society of Natural History, Marine Invertebrate catalogue numbers 4000 
and 4001, respectively. Two paratypes are in the collections of the Zoological Survey of 
India, Calcutta. The remaining specimens have been retained by the author. 

Type locality. — Mad'h Island, Bombay Coast, India, approximately 19°8'N., 
72°47'22"E.; A. A. Karande coll. 1969; 10 specimens. 

Comparative material. — I have examined specimens of the following species: 

T. divisa: western side of Panto Hole Bay, east of town of Marigot, Dominica; 
approximately 15°32'21"N., 61°17'31"W., intertidal on Tetraclita stalactifera (Lamarck); 
E. Kirsteuer and K. Rutzler coll., 1-10 May 1966 (see Ross, 1968:13). 

T. chinensis: Suo (Suao), Taiwan, approximately 24°35'45"N., 121°51'10"E., "... on 
sheltered undersurface of stones in the littoral"; F. Hiro coll., 30 May 1938 (see Hiro, 
1939:277). 

T. purpurascens: Eddystone Point, Tasmania, approximately 40°59'30"S., 148°20'E.; 
I. Bennett coll., 20 June 1964. The Nobbies, Phillip Island, Victoria, Australia, approx- 
imately 38°30'S., 145°16'E.; E. C. Pope coll.. May 1949. Little Papanui, Otago Peninsula, 
South Island, New Zealand, approximately 45°50'S., 170°43'E.; C. Hand coll., 4 Novem- 
ber 1959. 

T. darwini: Isle Hatake-zima, Tanabe Bay, Wakayma Prefecture, Japan, approx- 
imately 33°43' N., 125°21'30" E.; F. Hiro coll., 3 April 1928. 

Etymology. — The specific epithet honors Dr. Ashok A. Karande, Senior Science 
Officer, Naval Chemical and Metallurgical Laboratory, Bombay, India, who collected the 
specimens. 



■>■>! 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 4. Mandibles of Tetraclilella karandei n. sp. and related tetraclitellans. A, E, right and left, respectively, 
hololype (4000); B, F, right and left, respectively, paratype 400 1/b; C, G, right and left, respectively, paratype 
4001/c; D, H, right and left, respectively, paratype 4001/d; I, K., right and left, respectively, paratype 4001/e; J. 
right, paratype, Zool. Survey India; L, after Utinomi, 1962; M, from Dominica; N, from Taiwan; O, from 
Tasmania; P, from Japan. 



1971 ROSS: STUDIES ON THE TETRACLITIDAE 223 

DISCUSSION 

There are two groups in Tetraclitella based primarily on the morphology of the 
operculum. In the first, consisting o{ costata, pilsbryi, and darwini, the scutum is higher 
than wide and externally ornamented with one or more longitudinal rows of pits, and the 
tergum composes about one-half or more of the bulk of the operculum. In the bala- 
nomorphs a tall, narrow scutum generally correlates with a relatively tall shell; in these 
three species the shell is relatively tall. In the second group, consisting oi purpurascens, 
multicostata, divisa, chinensis, and karandei n. sp., the scutum is transversely elongated 
and lacks the longitudinal rows of pits, and the tergum composes less than one-half of the 
bulk of the operculum. I consider the costata group to be the phylogenetically more 
primitive on the basis of the opercular valves, which are characteristic of geologically early 
balanomorphs. 

One species in each of the above groups develops radii that are elevated well above the 
surface of the parietes {darwini and karandei). Radii develop essentially normal to the 
parietes and function to enlarge and strengthen the shell. Similar functions are served by 
the alae (Darwin, 1954: 36, 45-48), which are always non-tubiferous, contrary to the 
statements of Pilsbry (1928: 316), and Hiro (1939: 273). The sutural surface of the radius 
abuts against and fits into a furrow in the opposed compartment, the outer edge of which 
may be raised to form a lip, as in darwini and karandei. In darwini this lip, an extension of 
the parietes, is tubiferous. I infer that the elevated radii in darwini serve primarily as a 
means of developing a larger sutural surface for strengthening the shell, especially in the 
absence of sutural ridges and denticulae. Attempts to manually separate the plates in this 
species are rarely if ever successful. Conversely, the plates in karandei are easily separated 
from one another. However, in karandei the development of a prominent lip on the 
adjoining compartments (Fig. 2b) may serve to strengthen the articulation of the plates. 

Because the parietal plates of karandei are weakly articulated, and because karandei 
occupies a protected habitat low in the intertidal zone, it is reasonable to assume that the 
finger-like projections on the exposed radial surfaces serve a different function than the 
raised radii of darwini. I believe that these projections function primarily to scatter the 
initial energy of the incident currents into numerous smaller components. This would 
create turbulence or change the water flow pattern over the shell, and consequently 
enhance the fishing capabilities of the cirral net. 

The mode of growth of the shell in T. chinensis sets it apart from all other 
tetraclitellans. In the adult or large specimens the compartments are pierced by hollows, 
one in each of the laterals and two in both the rostrum and the carina. Hiro (1939: 274) 
considered them to be parietal tubes formed by the corrosion of the parietal wall, but it is 
evident from the young stages that initially these hollows are external to the parietes, and 
consequently they cannot be parietal tubes. The hollows result from the initial development 
of distally flaring extensions from the shell, the lateral tips of which subsequently meet and 
fuse in a manner somewhat analogous to the fusion of the terminally flanged radial 
buttresses in whale barnacles. I believe that this method of shell growth enables chinensis 
to rapidly develop a broad base of attachment in a high energy environment. Support for 
this inference comes from the fact that in the few adult specimens I have seen the shell is 
essentially circular in outline, lacks well preserved longitudinal ribs, and the peritreme is 
eroded. Alternatively, this method of shell growth may be a means to prevent over- 
crowding, but observations to support this suggestion are lacking. 

ACKNOWLEDGMENTS 

I thank A. A. Karande, Naval Chemical and Metallurgical Laboratory, India, Elizabeth C. Pope, the 



224 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Australian Museum, Huzio Utinomi, Seto Marine Biological Laboratory, Brian Foster, Auckland University, 
William A. Newman, Scripps Institution of Oceanography and Ernst Kirsteuer, American Museum of Natural 
History, for their help in providing me with comparative material. Anne Acevedo prepared figures 1 and 2. 

LITERATURE CITED 

Darwin, C. R 

1854. A monograph on the sub-class Cirripedia. The Baianidae, the Verrucidae, etc. London, Ray Society, 
684 p. 

Hiro, F. 

1939. Studies on the cirripedian fauna of Japan. IV. Cirripeds of Formosa (Taiwan) with some geogra- 
phical and ecological remarks on the littoral forms. Mem. Coll. Sci. Kyoto Imp. Univ. ser. B, 15(2): 

245-284. 

Karande, A. A. 

1966. The sessile barnacles (Cirripedia) of the Bombay Coast. J. Bombay Nat. Hist. Soc. 63(1): 139-151. 

Kolosvary, G. 

1941. Balaniden-Studien. Zool. Anz. 135(1/2): 41-45. 

1942. Studien an cirripedian. Zool. Anz. 137(7/8): 138-150. 

Kolosvary, G. and J. Wagner 

1941. Tengerbiologiai tanulmany a kacslabuak^puhatestuek es korallok tarsulasarol. A Tenger 31(1-3): 
1-16. 

Nilsson-Cantell, C. A. 

1921 . Cirripeden-Studien. Zur Kenntnis der Biologic, Anatomic und Systematik dicscr Gruppc. Zool. Bidr. 

Uppsala 7: 75-395. 
1930. Diagnoses of some new cirripedes from the Netherlands Indies collected by the Expedition of His 
Royal Highness the Prince Leopold of Belgium in 1929. Bull. Mus. Royal Hist. Nat. Belgique 6(4): 
1-2. 

Pilsbry, H.A. 

1928. Littoral barnacles of the Hawaiian Islands and Japan. Proc. Acad. Nat. Sci., Philadelphia 79: 305- 
317, pis. 24-26. 

Ross, A. 

1968. Bredin-Archbold-Smithsonian biological survey of Dominica. 8. The intertidal balanomorph Cirri- 
pedia. Proc. U. S. Natl. Mus. 125(3663): 1-23. 

1969. Studies on the Tetraclitidae (Cirripedia: Thoracica): Revision of Tetraclita. San Diego Soc. Nat. 
Hist.. Trans. 15(15): 237-251. 

1970. Studies on the Tetraclitidae (Cirripedia: Thoracica): A proposed new genus for the austral species 
Tetraclita purpurascens breviscutum. San Diego Soc. Nat. Hist., Trans. 16(1): 1-12. 

Utinomi, H. 

1962. Studies on the cirripedian fauna of Japan. VIII. Thoracic cirripeds from western Kyusyu. Publ. Seto 

Mar. Biol. Lab. 10(2): 21 1-239. 
1970. Studies on the cirripedian fauna of Japan. IX. Distributional survey of thoracic cirripeds in the 
southeastern part of the Japan Sea. Publ. Seto Mar. Biol. Lab 1 7(5): 339-372. 
Wood, W. 

1815. General conchology; or a description of shells arranged according to the Linnean System. London, 
246 p. 



Department of Invertebrate Paleontology, Natural History Museum, P. O. 
Box 1390. San Diego, California 92112. 




LIBRARy 

JUL «3 1971 

HARVARD 



STRATIGRAPHY OF THE POWAY AREA, 
SOUTHWESTERN CALIFORNIA 



GARY L. PETERSON 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 

VOL. 16, NO. 9 9 JULY 1971 



STRATIGRAPHY OF THE POWAY AREA, 
SOUTHWESTERN CALIFORNIA 

GARY L. PETERSON 



ABSTRACT.— Post-batholithic sedimentary rocks near Poway, California, which were previously mapped as 
"Poway Conglomerate," consist of three distinctively different formations. The Lusardi Formation (Late Cre- 
taceous) consists predominantly of very poorly sorted conglomerate containing an assemblage of locally de- 
rived clasts (Peninsular Ranges suite), which range in size from granules to boulders three meters in diameter. 
This formation strongly resembles the type Lusardi near Rancho Santa Fe and "pre-Poway fanglomerates" 
reported from several localities near Lakeside and Alpine to the southeast. Unconformably overlying the Lu- 
sardi Formation are two late Eocene formations: 1) the Friars Formation (La Jolla Group), consisting pre- 
dominantly of sandstone and shale, and 2) the Stadium Conglomerate (Poway Group). Conglomerates from 
either of the Eocene units are moderately well sorted and consist mostly of exotic cobble-sized metavolcanic, 
volcanoclastic, and quartzite clasts (Poway suite). 

The Lusardi Formation fills a long narrow channel cut subsequent to mid-Cretaceous orogenesis during 
a time of rugged topography. After Lusardi deposition, a more subdued erosion surface was developed on the 
Lusardi Formation and on the basement rocks, and the terrain underwent severe weathering. The Eocene 
formations were deposited on this deeply weathered erosion surface and received little locally derived coarse 
detritus. The Poway suite of clasts accumulated in southwestern California after having been derived from the 
east and transported across the low-lying erosion surface. 

RESUMEN.— Las rocas sedimentarias post-batoliticas cercanas a Poway, California, mapeadas previamente 
como "Conglomerado Poway," estan constituidas por tres formacions bien diferentes. La Formacion Lusardi 
(Cretaceo Superior) esta constituida predominantemente por conglomerados de muy pobre seleccion, cuyos 
clastos tienen una procedencia local (Peninsular Ranges suite) y varian en tamario desde granulos hasta pe- 
riascos de tres metros de diametro. Esta formacion tiene un fuerte parecido con la Formacion Lusardi-tipo 
cerca al Rancho Santa Fe y con los conglomerados de abanicos aluviales, pre-Poway, reportados en varias 
localidades cerca de Lakeside y hacia el sureste en Alpine. Dos formaciones del Eoceno superior se super- 
ponen inconformablemente sobre la Formacion Lusardi: 1) la Formacion Friars (del Grupo La Jolla) com- 
puesta principalmente de areniscas y lutitas, y 2) el Conglomerado Stadium (del Grupo Poway). Los 
conglomerados de eualquiera de las unidades del Eocene, estan moderadamente bien seleccionados y con- 
sisten principalmente de bloques exoticos (de 5 a 15 cm en tamaiio) de rocas metavolcanicas, volcanoclasticas 
y cuarcitas ( Powan suite). 

La Formacion Lusardi rellena un canal largo y estrecho de la arrugada superficie producida despues de 
la orogenesis del Cretaceo medio. Al terminar la depositacion del Lusardi y bajo la influencia de una severa 
meteorizacion se desarrollo una superficie de erosion mas suave, tanto en las rocas del basemento como en la 
Formacion Lusardi. Las Formaciones del Eoceno se depositaron sobre esta, profundamente meteorizada, 
superficie de erosion recibiendo poco aporte local de detritos gruesos. La serie de clastos del Poway se derivo 
aparentemente del este, siendo transportados a travez de la yaciente superficie de erosion y acumulados en la 
parte sur-occidental de California. 

INTRODUCTION 

The geology of the Poway area, CaUfornia, consists of an igneous and metamorphic 
basement complex overlain by about 150 to 200 meters of nearly flat lying sedimentary 
rocks. On previously published geologic maps including the Poway area, all of the sedimen- 
tary deposits were included under the designation "Poway Conglomerate" (Ellis and Lee, 
1919; Hanna, 1926a). As implied by the name, the Poway area was regarded as the type 
locality for that stratal unit. Ellis and Lee considered the "Poway Conglomerate" to be 
Pliocene in age because it was composed in large part of the same type of materials present 
in the coarser parts of the Pliocene San Diego Formation. Hanna (1926a; 1926b) and all 
subsequent investigators recognized the "Poway Conglomerate" to be late Eocene in age on 
the basis of fossils. The coarser materials in the San Diego Formation which strongly re- 
semble those in the "Poway Conglomerate" are, in fact, the same; the source for much of 
the San Diego Formation was the "Poway Conglomerate." 

SAN DIEGO see. NAT. HIST, TRANS. 16(9): 225-236, 9 JULY 1971 



226 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



RANCHO SANTA FE 



LA JOLLA 






L. 



10 



KM 



POWAY 



LAKESIDE 



N 



ALPINE 



PT. LOMA 



SAN 
DIEGO 




Figure \. Index map of southwestern California showing localities mentiimed in the text. 

About five years ago several students practicing geologic mapping in the vicinity of 
Poway reported a conglomerate that difiered significantly from typical exposures of the 
"Poway Conglomerate." This anomalous conglomerate came to mind again subsequent to 
detailed mapping in the Rancho Santa Fe area ( Fig. 1 ), where a thick boulder conglomerate 
(now recognized as the Upper Cretaceous Lusardi Formation) that differs markedly from 
the Eocene conglomerates in texture and clast content lies uncomformably beneath the 
Eocene strata (Nordstrom. 1970; Peterson and Nordstrom. 1970). 

Re-examination of the sedimentary rocks cropping out in the vicinity of Poway in- 
dicated the presence of not one but three distinct and easily mappable formations. The first, 
or lowest, rock unit is a very coarse, severely weathered conglomerate correlated with the 
Upper Cretaceous Lu.sardi Formation of the Rancho Santa Fe area (Nordstrom. 1970). The 
middle unit is predominantly sandstone and shale and is here regarded as an extension of 
the newly recognized late Eocene Friars Formation (La Jolla Group) of Kennedy and 
Moore ( 197 1 ). The upper unit is a thick and widespread cobble conglomerate and is corre- 
lated with the late Eocene Stadium Conglomerate (Poway Group) of Kennedy and Moore 
(1971). 

The purpose of this paper is to describe and outline the principal distinctions between 
the three formations, to show their distributions on a geologic map, to correlate the forma- 
tions with those mapped and described in the San Diego to the west-southwest and with 
formations recognized to the east-southeast in the Alpine-Lakeside area, and to indicate a 
local and regional sequence of events implied by these observations and interpretations. 



1971 



PETERSON: STRATIGRAPHY OF POWAY AREA 



227 



The geology of the Poway area is depicted in figure 2. My principal interest was in the 
sedimentary rocks: thus the basement complex was not subdivided. The basement rocks 
consist predominantly of the mid-Cretaceous Southern California batholith (Larsen, 1948; 
Bushee et ai, 1963) and a few small patches of the pre-batholithic Santiago Peak Volcanics 
of Late Jurassic age (Fife et ai, 1967). An erosion surface having in excess of 300 meters of 
local relief was developed on the basement complex and the sedimentary formations rest on 
this irregular surface. The relief on the basement rocks exceeds the total thickness of the 
younger flat-lying sedimentary deposits by over 100 meters; thus the area is characterized 
by hills of relatively ancient basement rocks locally protruding through and standing well 
above the younger sedimentary deposits. 




Figure 2. Geologic map of the Powav area. 

LUSARDI FORMATION 

The Lusardi Formation crops out in a narrow, six kilometer long belt extending east- 
northeast from Poway (Fig. 2). Apparently these deposits must have filled a former channel, 
although the present topography is reversed, and the deposits cap a long narrow ridge with 
the modern drainage incised deeply into the basement complex on either side. The ridge is 
utilized as a roadway and excellent Lusardi exposures can be observed in some of the cuts 
(Fig. 3). 

The long exposure varies in altitude from about 550 meters near the eastern limit to 
less than 200 meters at Poway. Thickness of the Lusardi ranges from about 20 to 30 meters. 

The westernmost Lusardi exposure appears to fill a northeast-trending, broadly V- 
shaped channel which terminates at Poway Valley. The channel probably extends farther to 
the west beneath the alluvium and the Eocene formations. 

The Lusardi conglomerate consists of extremely poorly sorted clasts ranging in size 
from granules to boulders exceeding three meters in diameter. The clasts range in shape 
from angular to spheroidal; most are at least partially rounded. The conglomerate matrix is 
a poorly sorted, t^ner grained clastic assemblage dominantly derived from grus. The con- 
glomerate has been severely weathered and many of the plutonic clasts have decomposed 
to grus; in such cases they are difficult to distinguish from the matrix. Also, many of the 
clasts are physically disintegrated in situ and yield sharp angular fragments giving the unit 



228 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



the appearance of a coarse sedimentary breccia. The various clast types differ markedly in 
resistance to weathering. Therefore, where an outcrop on the surface is inspected, it is domi- 
nated by the more resistant clasts, whereas in a deep road cut the entire assemblage is ex- 
posed. 







kiT"»*»- ■-^'■^■■•■S -.T-JTt . -4 .'*■*• ^A"- '.*.«^ "**• 1 



Figure 3. Outcrop of Lusardi Formation in road cut along Poway to Lakeside highway about two miles east of 
Poway. Note the typical texture of this formation. Striped bar used for scale in photograph is a Jacobs staff (five 
feet in length). 

Some of the largest clasts are coarse-grained diorite and quartz diorite boulders 
slightly more than three meters in diameter. Some of the diorite clasts are severely weath- 
ered and contain finer grained resistant xenoliths, giving the appearance that the xenoliths 
are "cobbles'' in a matrix of grus. Another abundant plutonic clast type is a resistant, me- 
dium-grained granodiorite containing quartz phenocrysts. The plutonic rock types listed 
above, together with minor amounts of aplite and vein quartz, constitute an estimated 60 
per cent of the clasts in the conglomerate. All are common rock types found in the Southern 
California batholith in the Poway area and the region to the east. 

Other clast types include a number of fine to very fine grained, light brown, greenish 
gray, and medium to dark gray metamorphosed tuff's. One of the most distinctive and com- 
mon types is a medium gray weathering welded tuff containing finely crenulated flow band- 
ing; where broken to reveal the inner appearance, the rock appears very fine grained, dark, 
and without internal structure. Other clast types include very fine grained black hornfelsic 
rocks, and minor amounts of fine-grained volcanic breccia. All of these clast types resemble 
some of the more metamorphosed portions of the Santiago Peak Volcanics. The total as- 
semblage of clasts found in the Lusardi is referred to as the Peninsular Ranges suite and is 
characteristic of Cretaceous formations in the San Diego area (Peterson er a/.. 1968; Peter- 
son, 1970a; Peterson and Nordstrom, 1970). 

The Lusardi Formation was not recognized on previously published geologic maps of 
the Poway area, and it was included with the basement complex (Ellis and Lee. 1919; 
Hanna, 1926a). Likewise in the Rancho Santa Fe area, the type Lusardi appeared on pre- 



1971 PETERSON: STRATIGRAPHY OF POWAY AREA 229 

vious geologic maps labeled as everything from "weathered basement rocks" to "Quater- 
nary terrace deposits." The easternmost portion of the elongate Lusardi outcrop in the 
Poway area appeared on a map designated as "pre-Poway fanglomerate" (Gastil and 
Bushee, 1961). 

FRIARS FORMATION 

In previous studies including the Poway area, all of the Eocene strata were mapped as 
the "Poway Conglomerate" (Ellis and Lee, 1919; Hanna. 1926a), although Hanna clearly 
recognized that his "Poway Conglomerate" could be locally subdivided into smaller stra- 
tigraphic units, some of which were not conglomerate. In the Poway area, which serves as a 
loosely defined type area for the "Poway Conglomerate." I have subdivided the Eocene sec- 
tion and have recognized two widespread mappable formations. The lower formation con- 
sists predominantly of sandstone and shale; the upper is dominated by conglomerate. 

In the first general revision of the Eocene stratigraphic nomenclature since Hanna's 
description of the La JoUa quadrangle, Kennedy and Moore (1971) recognized two groups 
of Eocene formations: the La Jolla Group, which approximately coincides with the La Jolla 
Formation as mapped by Hanna. and the Poway Group, which approximates the previous 
"Poway Conglomerate." It is clear tYom the map of the San Diego area presented by Ken- 
nedy and Moore (1971, figure 1), which overlaps the western margin of the geologic map 
accompanying this report (Fig. 2), that they consider my lower sandstone and shale unit to 
belong to the La Jolla Group and my upper conglomeratic unit to belong to the Poway 
Group. In this report, I follow the stratigraphic nomenclature presented by Kennedy and 
Moore and further suggest that my lower formation is equivalent to their newly defined 
Friars Formation and that my upper formation is equivalent to their newly defined Sta- 
dium Conglomerate. 

The Friars Formation (La Jolla Group) of the Poway area lies unconformably on the 
basement complex and is gradational with the overlying Stadium Conglomerate (Poway 
Group). It crops out on the lower slopes of the hills along the southern margin of Poway 
Valley and the area northwest of Poway (Fig. 2). The Friars Formation reaches a maximum 
thickness of about 30 meters. In general, this formation is poorly exposed because of low 
relief and a cover of coUuvium derived from the overlying Stadium Conglomerate. The best 
exposures are in artificial cuts. 

Despite the generally poor exposures, the Friars Formation is fairly easy to map. The 
contact with the Stadium Conglomerate coincides closely with the 200 meter contour line 
throughout the area and is marked by a slight change in slope and a change in vegetation. 
The Friars Formation is generally easily separated from the basement rocks, except in a few 
places where the basement rocks are severely weathered. In such places the basement rocks, 
although superficially appearing very similar to the Friars Formation, contain at least a few 
relict features such as joint planes, foliation, or small quartz veins by which they may be 
recognized. 

The Friars Formation is dominated by green to light brown, generally thickly bedded 
sandstone and shale (some geologists might prefer to use the term "mudstone" for the as- 
semblage). Grain sizes range from that of clay and silt to coarse sand. Typically the rocks 
are neither well sorted nor well stratified. In addition, the Friars Formation locally contains 
some thin beds of conglomerate and a few fairly sizeable lenses of conglomerate character- 
ized by the Poway suite of clasts (more fully noted in the following section). 

No fossils were found in any of the Friars outcrops examined in the Poway area. Ken- 
nedy and Moore (1971) reported the age of the formation to be middle and late Eocene, as 
based on fossil evidence and stratigraphic position at the type section of the formation 



230 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



along the northern margin of Mission Valley. 

STADIUM CONGLOMERATE 

The Stadium Conglomerate (Poway Group) is the thickest, most extensive, and best 
exposed stratigraphic unit in the Poway area. Along the southern side of Poway Valley, it is 
up to 150 meters thick. In the area to the northwest of Poway, it is up to about 50 meters 
thick. An excellent section of the Stadium Conglomerate is well exposed along Pomerado 
Road in the southwest corner of the map area (Fig. 2). 




Figure 4. Outcrop i>f Stadium Conglomerate along Pomerado Road about one-half mile oil' the southwestern 
corner of the map (Fig. 2). Note the l\pical texture of this conglomerate and the presence of sandstone lenses. 
Scale is .lacobs staff. 

Although the Stadium Conglomerate is dominated by conglomerate, as implied by the 
name, beds and lenses of sandstone and shale are locally evident, especially in the lower 
portion. The finer grained sediments in the lower part closely resemble those in the Friars 
Formation, whereas higher in the section the beds and lenses of sandstone and shale and 
the matrix of the conglomerate are cleaner, better sorted, and white to light brown. Many of 
the prominent sandstone lenses within the conglomerate probably represent sand bars de- 
veloped in a river .system. 



1971 PETERSON: STRATIGRAPHY OF POWAY AREA 231 

The Stadium Conglomerate is typically fairly well sorted, at least relative to the Lu- 
sardi conglomerate (compare Fig. 3 and 4). Clast sizes range from granules to boulders 60 
centimeters in diameter, but clasts over 30 centimeters in diameter are rare. Typically, the 
clasts are subrounded to rounded cobbles and small boulders. The texture of the Stadium 
Conglomerate and of other Eocene conglomerates in the San Diego area differs so 
markedly from that of the Lusardi that the two may be readily recognized on that basis 
alone (Peterson. 1970a). 

The types of clasts found in the Stadium Conglomerate and in other Eocene and post- 
Eocene formations in the San Diego area are highly distinctive and easily recognized. The 
clasts consist predominantly of slightly metamorphosed rhyolitic to dacitic volcanic and 
volcanoclastic rocks, with a smaller but significant amount of quartzite. The various clast 
types (together referred to as the Poway suite of clasts) and their proportions are well de- 
scribed by Bellemin and Merriam ( 1958), De Lisle el al. (1965), and Woodford et al. ( 1968). 

No fossils were found in the Stadium Conglomerate of the Poway area. However, in 
other parts of the San Diego area, the Poway Group including the Stadium Conglomerate 
has yielded a variety of marine and non-marine late Eocene fossils (Hanna, 1926b: Dusen- 
bury, 1932; Cushman and Dusenbury, 1934; Stock, 1937, 1938; Kennedy and Moore. 
1971). Evidently the Stadium Conglomerate was deposited very near sea level and repre- 
sents a variety of fluvial, estuarine. and nearshore-marine depositional environments. 

RELATIONSHIP BETWEEN CRETACEOUS AND EOCENE FORMATIONS 

The westernmost outcrop of the Cretaceous Lusardi Formation is capped by a thin 
patch of the Stadium Conglomerate. This is the only locality withm the map area where the 
Eocene rocks are in contact with the Lusardi Formation. The Stadium Conglomerate at this 
locality consists of a thin cobble conglomerate (approximately 7 meters thick), capping the 
crest of the hill, underlain by a thin (about 7 meters) unit of greenish sandstone and shale. 
Underlving this latter unit is the bouldery Lusardi Formation. Exposures of the three units 
are poor except for several road cuts. The conglomerate cap is identical in all respects to the 
Stadium Conglomerate as mapped throughout the area (figure 2). The sandstone and shale 
unit is lithically identical to the Friars Formation and to the lenses of sandstone and shale in 
the lower portion of the Stadium Conglomerate. 

The Lusardi Formation of the Poway area is interpreted as a deposit formed by a very 
fast flowine. turbulent river. The character of the deposits susaests that the Lusardi filled a 
long narrow, fairly steep-walled canyon, although this topography is no longer evident. The 
Lusardi channel (or canyon) fill extended from the northeast into the Poway area, and 
probably continued far to the west of Poway. 

After deposition of the Lusardi conglomerate, the area underwent erosion. A much 
wider, north to south sloping valley was cut across the Poway area. During, or following, 
this erosional episode the terrane (consisting of the Lusardi Formation and the basement 
rocks) underwent severe weathering. When deposition began again, the Eocene formations 
were deposited on the deeply weathered surface, filling in the low areas first and then lap- 
ping over onto the adjacent highlands. 

The initial deposits, the Friars Formation, are both mineralogically and texturally im- 
mature. In gross character, the coarser grained sandstones of this formation strongly re- 
semble grus. The finer grained portions were not studied in detail, but casual observation 
suggests that they are dominated by weathered products derived from the deeply weath- 
ered basement complex and probably from the Lusardi Formation as well. Much of the 
finer sediments of the Friars Formation and the lower portion of the Stadium Con- 
glomerate were evidently derived locally. The conglomerates with the exotic Poway suite of 



232 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



clasts, however, had to be transported into the area from a considerable distance. 

REGIONAL IMPLICATIONS 

The sequence of post-bathohthic rock units in the Rancho Santa Fe area (Fig. 5) in- 
cludes the Lusardi Formation, which is unconformably overlain by the Eocene La Jolla 
Group. The unconformity between the two units can be demonstrated to have about 130 
meters of relief, although both rock units are essentially flat lying ( Peterson and Nordstrom, 
1970). The identical sequence of rock units, unconformable relationship between them, and 
the implied sequence of events is evident in the Poway area except that the Eocene rock 
units are far more conglomeratic and appear to be predominantly non-marine. 



POway TERRACE 




BALLENO GRAVELS 



'V';.' '■"-'----/: cdvJ"''*^'' 






,£BN 



ILPINE- LAKESIDE 



LA JOLLA- PT LOMA 



Figure 5. Correlation diagram emphasizing relationships between Cretaceous and Eocene rock units in the 
northern and eastern part o^ the San Diego area. Thickness of rock units is not to scale, but is roughly 
proportional. 

East and southeast of the Poway area, a number of small and widely scattered outcrops 
of "pre-Poway fanglomerate deposits" were reported and briefly described in a field trip 
guidebook (Gastil, 1961; Gastil and Bushee. 1961). Most of the outcrops are within 15 ki- 
lometers of the communities of Alpine and Lakeside (Fig. 1). I revisited several of the local- 
ities for comparative purposes. In gross character, these deposits strikingly resemble the 
Lusardi Formation of the Poway area and the type Lusardi near Rancho Santa Fe. The 
deposits are very poorly sorted and contain a wide variety of clasts derived from the local 
basement complex (Peninsular Ranges suite). Some of the clasts are exceptionally large (di- 
ameter greater than three meters) and many clasts are deeply weathered. Locally the con- 
glomerate has a reddish matrix; elsewhere the matrix is light brown, green, or gray. Clast 
types characteristic of the Eocene formations (Poway suite) are absent. 

Where field relations are evident (see especially the southwest and central portions of 
geologic map number 2 of Gastil and Bushee. 1961), the "pre-Poway" conglomerate ap- 
pears to be deeply channeled into the basement complex and is overlain by the "Poway 
Conglomerate" (or the equivalent "Ballena Gravels"). On the basis of stratigraphic posi- 
tion and lithic similarity, I regard all the outcrops of "pre-Poway fanglomerates" reported 



1971 PETERSON: STRATIGRAPHY OF POWAY AREA 233 

by Gastil and Bushee (1961) as further exposures of the Late Cretaceous Lusardi Forma- 
tion. 

No trace of fossils could be found in any of the Lusardi outcrops in any of the areas 
discussed, nor does it appear likely that any will be found. The extremely coarse texture and 
the deeply weathered nature of these deposits provides a very unfavorable environment for 
preservation of fossils. In spite of the absence of fossils, a reasonable argument can be pre- 
sented to indicate that the Lusardi is Late Cretaceous in age. Correlation of the units from 
area to area on a physical basis is shown in Figure 5. When the Lusardi is traced to the west, 
it extends beneath the Point Loma Formation in the Carlsbad area and in the subsurface of 
the La JoUa-Point Loma area where it constitutes the lowest formation in the Late Cre- 
taceous (Campanian and Maestrichtian) Rosario Group (Kennedy and Moore, 1971). In 
addition, the clast content of the Lusardi is similar, but not identical, to conglomerates 
found in the upper part of the Rosario Group (Cabrillo Formation) and is unlike other sedi- 
mentary deposits (Eocene. Pliocene, Pleistocene, or Recent) of the San Diego area (Peter- 
son, 1970a). 

The Lusardi Formation is apparently of much greater extent than was previously rec- 
ognized (Nordstrom, 1970; Peterson and Nordstrom, 1970). It would not be surprising to 
find still further outcrops now that it has been recognized as a separate, distinct, and wide- 
spread stratigraphic unit. Evidently, it was deposited over a large part of the San Diego 
region following the emplacement of the Southern California batholith and the subsequent 
uplift necessary to expose those deep-seated rocks. During Late Cretaceous time the San 
Diego region was probably topographically very rugged and undergoing rapid erosion. The 
high-relief topography was partially filled with debris derived from the batholithic and pre- 
batholithic rocks and representing a very high energy depositional environment. Very 
coarse stream deposits, alluvial fan deposits, and mudflow deposits were spread over the 
area to unknown but highly variable depths. In the western part of the San Diego area, the 
marine Point Loma and Cabrillo Formations were deposited over the Lusardi con- 
glomerates (Fig. 5). 

Following the Late Cretaceous depositional episode, the region underwent uplift, pos- 
sibly slight deformation, and a widespread erosion surface of low to moderate relief was 
produced across the Cretaceous sedimentary rocks and the basement rocks. This surface 
was referred to as the "sub-La Jolla unconformity" in the coastal portion of the San Diego 
area (Peterson and Nordstrom, 1970) and the "old erosion surface" to the east in the region 
around Alpine and Lakeside (Gastil, 1961; Gastil and Bushee, 1961;Minch, 1970). During 
this supra-baselevel episode, most of the Lusardi deposits were dissected and erosionally 
removed, particularly in their eastern extent. The remaining remnants were left in low lying 
areas (such as near Rancho Santa Fe), in buried canyons (such as at Poway), in areas that 
were probably distant from major drainages during the time of erosion, or in areas where 
the formation was covered by the Point Loma and Cabrillo Formations. 

The "old erosion surface" had from several hundred to several thousand feet of local 
relief from place to place. During or after the development of the erosion surface, the region 
apparently underwent an episode of deep and severe weathering. The results of this weath- 
ering are evident in all Lusardi outcrops. A similar observation was recorded from an area 
several kilometers south of Tijuana, Baja California. Flynn ( 1970: 1793) described the pres- 
ence of a widespread deeply weathered zone (paleosol) developed on the Cretaceous Re- 
donda (probably equals Lusardi) and Rosario Formations and on the basement rocks. The 
soil ranged up to nearly 15 meters thick and was overlain by the Eocene Delicias and 
Buenos Aires Formations (equivalents to the La Jolla Group of the San Diego area). 

The Eocene sedimentary rocks of the San Diego area were deposited on "the old ero- 



234 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

sion surface" without totally destroying the relief. Thus the unconformity beneath the Eo- 
cene rocks has several hundred to several thousand feet of relief, and hills composed of pre- 
Eocene rocks locally protrude through the Eocene cover (Hanna, 1926a; Peterson and 
Nordstrom. 1970). 

With the beginning of Eocene deposition, the Poway suite of clasts first arrived in the 
San Diego area. The clasts were evidently transported a considerable distance, at least 100 
kilometers and probably more, for there is no known local source area. Potential distant 
source areas from the Mojave Desert to Sonora, Mexico have been proposed (De Lisle et ai, 
1965; Merriam, 1968; Woodford e/ a/., 1968; Minch, personal communication, 1970). The 
intent here is not to resolve the Poway clast provenance problem. It is sufficient to say that 
these exotic clasts did not arrive in the San Diego area until mid-Eocene time and thus they 
have a chronologic significance. Regardless of where they came from, they are abundant in 
all Eocene conglomerates of the San Diego area and are absent in pre-Eocene units. 

In marked contrast to the Cretaceous conglomerates, the Eocene conglomerates con- 
tain a very low proportion of clast types that might have been derived from the local base- 
ment rocks. Outcrops containing more than 10 per cent clasts resembling the pre- 
batholithic and batholithic rocks are rare. It should be pointed out that, although some 
clasts resemble the local basement rocks, they too may have been transported into the San 
Diego area along with the exotic Poway clasts (Minch, 1970). The paucity of locally derived 
coarse detritus suggests that the San Diego region was relatively low lying during Eocene 
deposition. Some of the fine detritus found in the Eocene formations, such as that of the 
Friars Formation and the lower portion of the Stadium Conglomerate near Poway, was 
probably locally derived and contributed by minor streams. The Poway suite of clasts, how- 
ever, had to be transported across the low lying ''old erosion surface" to the site of accumu- 
lation in the San Diego area. 

Following Eocene deposition, the San Diego area has undergone several uplifts in- 
cluding thecuttingof three widespread coastal terraces (Ellis and Lee, 1919; Hanna, 1926a; 
Peterson, 1970b). This post-Eocene uplift and erosion has resulted in extensive dissection of 
the Eocene deposits, locally revealing the underlying fragments of the Lusardi Formation. 



ACKNOWLEDGMENTS 

I would like to thank W. J. Elliott, A. H. James, and R. T. La Borde for pointing out the seemingly anomalous 
conglomerate in the Poway area. In addition, I would like to thank J. A. Minch, C. E. Nordstrom, M. P. Kennedy 
and R. G. Gastil tor many stimulating discussions concerning the conglomerates of the San Diego area. Thanks are 
due to Armando Estrada for translation of the abstract into Spanish. 



LITERATURE CITED 

Bellemin, G. J., and R. H. Merriam 

1958. Petrology and origin of the Poway Conglomerate, San Diego County, California. Geol. Soc. Amer. 
Bull. 69: 199-220. 

Bushee, J., J. Hoiden. B. Geyer, and G. Gastil 

1963. Lead-alpha dates for some basement rocks of southwestern California. Geol. Soc. Amer. Bull. 74:803- 
806. 

Cushman, J. A., and A. N. Dusenbury, Jr. 

1934. Eocene foraminifera of the Poway Conglomerate of California. Contr. Cushman Lab. Foram. Res. 
10:51-65. 

De Lisle, M., J. R. Morgan, J. Heldenbrand, and G. Gastil 

1965. Lead-alpha ages and possible sources of metavolcanic rock clasts in the Poway Conglomerate, south- 
west California. Geol. Soc. Amer. Bull. 76; 1069- 1074. 



1971 PETERSON: STRATIGRAPHY OF POWAY AREA 235 

Dusenbury, A. N., Jr. 

1932. A faunule from the Poway Conglomerate, upper middle Eocene of San Diego County, California. Mi- 
cropaleontology 3:84-95. 

Ellis. A. J., and C. H. Lee 

1919. Geology and ground waters of the western part of San Diego County, California. U.S. Geol. Survey 
Water-Supply Paper 446: 1-321. 

Fife, D. L., J. A. Minch, and P. J. Crampton 

1967. Late Jurassic age of the Santiago Peak Volcanics, California. Geol. Soc. Amer. Bull. 78:299-304. 

Flynn. C. J. 

1970. Post-batholithic geology of the La Gioria-Presa Rodriguez area, Baja California, Mexico. Geol. Soc. 
Amer. Bull. 81:1789-1806. 

Gastil. G. 

1961. The elevated erosion surfaces. In, Field trip guidebook. San Diego County. Geol. Soc. Amer. 
(Cordilleran Section) 57th Ann. Mtg., 1-4. 

Gastil, G., and J. Bushee 

1961. Geology and geomorphology of eastern San Diego County. In, Field trip guidebook. San Diego 
Countv. Geol. Soc. Amer. (Cordilleran Section) 57th Ann. Mtg.. 8-22. 

Fianna, M. A. 

1926a. Geology of the La Jolla quadrangle, California. Univ. California Publ. Geol. Sci. 16: 187-246. 
1926b. An Eocene invertebrate fauna from the La Jolla quadrangle. California. Univ. California Publ. Geol. 
Sci. 16:247-398. 

Kennedy. M. P., and G. W. Moore 

1971. Stratigraphic relations of Upper Cretaceous and Eocene formations, San Diego Coastal area, Califor- 
nia. Amer. Assoc. Petrol. Geol. Bull. 55:709-722. 

Larsen, E. S., Jr. 

1948. Batholith and associated rocks of Corona. Elsinore. and San Luis Rey quadrangles, southern Califor- 
nia. Geol. Soc. Amer. Mem. 29: 1 - 1 82. 

Merriam, R. H. 

1968. Geologic reconnaissance of northwest Sonora. In, Proceedings of conference on geologic problems of 
San Andreas fault system. Stanford Univ. Publ. Geol. Sci. 1 1 :287. 

Minch, J. A. 

1970. Early Tertiarv paleogeographv of a portion of the northern Peninsular Range. //;, Pacific slope 
geology of northern Baja California and adjacent Aha California. Amer. Assoc. Petrol. Geol. (Pacific 
Section) Fall Field Trip Guidebook, 4-9. 

Nordstrom, C. E. 

1970. Lusardi Formation: a post-batholithic Cretaceous conglomerate north of San Diego, California. Geol. 
Soc. Amer. Bull. 81:601-606. 

Peterson, G. L. 

1970a. Distinctions between Cretaceous and Eocene conglomerates in the San Diego area, southwestern Cal- 
ifornia. In, Pacific slope geology of northern Baja California and adjacent Alta California. Amer. 
Assoc. Petrol. Geol. (Pacific Section) Fall Field Trip Guidebook. 90-98." 

1970b. Quaternary deformation of the San Diego area, southwestern California. ///, Pacific slope geology of 
northern Baja California and adjacent Alta California. Amer. Assoc. Petrol. Geol. (Pacific Section) 
Fall Field Trip Guidebook, 120-126. 

Peterson, G. L., R. G. Gastil, J. A. Minch, and C. E. Nordstrom 

1968. Clast suites in the late Mesozoic-Cenozoic succession of the western Peninsular Ranges province, 
southwestern California and northwestern Baja California (abst.). Geol. Soc. Amer. Spec. Paper 

115:177. 

Peterson. G. L.. and C. E. Nordstrom 

1970. Sub- La Jolla unconformity in vicinity of San Diego, California. Amer. Assoc. Petrol. Geol. Bull. 

54:265-274. 

Stock. C. 

1937. An Eocene titanothere from San Diego County. California, with remarks on the age of the Poway 
Conglomerate. Natl. Acad. Sci. Proc. 23:48-53. 

1938. A tarsiid primate and a mi.xodectid from the Poway Eocene, California. Natl. Acad. Sci. Proc 24288- 
293. 



236 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Woodford. A. O.. E. E. Welday, and R. H. Merriam 

1968. Siliceous tuff clasts in the upper Paleogene of southern California. Geol. Soc. Amer. Bull. 79:1461- 
1486. 



Department of Geology, San Diego State College, San Diego, California 92115. 



:3 - IN-H^ O;L0oP U'^OJ 




<^c 



MUS, COMP. ZOOL. 
LIBRARY 

SEP 10197] 

I^ARVARD 
UNfViftSlTY 



HERPETOFAUNA OF THE PACIFIC COAST 
OF NORTH CENTRAL BAJA CALIFORNIA, MEXICO, 
WITH A DESCRIPTION OF A NEW SUBSPECIES 
OF PHYLLODACTYLUS XANTI 



DENNIS L BOSTIC 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 

VOL. 16, NO. 10 25 AUGUST 1971 



HERPETOFAUNA OF THE PACIFIC COAST 
OF NORTH CENTRAL BAJA CALIFORNIA, MEXICO, 
WITH A DESCRIPTION OF A NEW SUBSPECIES 
OF PHYLLODACTYLUS XANTI 

DENNIS L. BOSTIC 



ABSTRACT.— Three species of lizards are recorded from the Pacific slope of Baja California, Mexico, for 
the first time: a leaf-toed gecko, Phvllodactylus xanti sloani n. subsp., Crotaphvtus collaris and Sauromalus 
australis. The distribution, pattern, and scutellation of Gerrhonotus multicarinatus spp. indicates a south- 
ward expansion of its range since glacial maxima via the cool, moist, coastal corridor, and its possible in- 
tegradation with G. paucicarinatus. A southward coastal corridor diff"usion may also be true for Tantilla 
planiceps eiseni, Coleon vx variegalus abbot ti and Lichanura roseofusca gracia. Of the 29 species of amphibi- 
ans (2), lizards ( 16), and snakes (11) collected, only one lizard, Cnemidophorous labialis, is considered en- 
demic to the Central Desert of Baja California. Homogeneity of habitats, the moderate climate and the extir- 
pation of the Peninsular desert herpetofauna during glacial maxima probably have been important factors 
in reducing or limiting species diversity and endemism. 

INTRODUCTION 

The coastal deserts of North America, of which more than 2000 miles are confined to 
Baja California and Sonora, Mexico, remain biologically unknown because of their relative 
inaccessibility, lack of potable water, and rugged terrain. Wiggins (1960a) identified these 
and other regions in Baja California as in need of more careful biological exploration. One 
area he mentioned was the Pacific coastal region between El Rosario (30°N) and the south- 
ern boundary of the state of Baja California (28°N; Fig. 1). Excluding the immediate areas 
of El Rosario and Rosarito, where the main road approaches within ten miles of the ocean, 
this region has not been explored herpetologically. 

In the spring and summer of 1969, 1 made several trips (Table 1) into the area in order 
to: 1) better ascertain the distributional limits of the herpetofauna, 2) gather ecological 
data; and 3) collect specimens for studies of geographical variation and evolution. 

METHODS AND MATERIALS 

A Taylor sling psychrometer and a Dwyer wind gauge (0-60 mph) were used to meas- 
ure relative humidity and wind speed. A Taylor soil thermometer (0-50°C) and a multi- 
channel tele-thermometer unit were used to record soil (approximately 0.5cm beneath 
surface) and air temperatures (approximately 0.5cm above surface). Time (Standard) is ex- 
pressed in 24 hour fashion. Throughout this paper when counts or measurements are pre- 
sented in the following manner: 1 1 ±1.3(10-12)18, the first figure refers to the arithmetic 
mean, the second figure to the standard error of the mean, the figures in parentheses to the 
range, and the last figure to the number of observations. Occasionally, the standard error of 
the mean is omitted, but the order, with this exception, remains the same. Standard devia- 
tion is indicated by S.D. 

All snout-vent measurements have been rounded off to the nearest whole number and 
other measurements to the nearest tenth. 

Within each major systematic grouping the species are arranged alphabetically by 
genus. I have not been consistent in the treatment of subspecies and have omitted available 
trinomials where geographical variation is poorly known. All material collected has been 
deposited in the collections of the San Diego Society of Natural History. 

SAN DIEGO see. NAT. HIST., TRANS. 16 ( 10): 237-264, 25 AUGUST I97I 



238 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



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Figure 1. Map of the central region of Baja California, Mexico. Modified from Gerhard and Gulick, 1966. 



1971 



BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 



239 



DESCRIPTION OF THE AREA 

GENERAL GEOGRAPHY 

The Pacific coast of Baja California between 30°N and 28°N is notably irregular, with 
many small embayments. The coastal strand is hilly to mountainous, and is frequently in- 
terrupted with valleys, coastal plains and marine terraces. The only well-defined mountain 
range is the Sierra Colombia, with summits near 762 meters. 

The area lies within the North American Desert Province (Shreve, 1942), but thus far 
there has been no agreement as to a name for that part of the province in the middle of the 
peninsula roughly delimited in the north by the southern tip of the Sierra de San Pedro 

Table 1. Herpetological Collecting Stations in the Central Desert of Baja California del Norte, Mexico. 



Station Date 



Locality 



1 


30 March 


6.6 miles 


2 


2-4 August 




3 


3 April 


11.8 miles 


4 


3 April 


19 miles 


5 


30-31 March 


23.5 miles 


6 


1,3 April 


24.5 miles 


7 


2 April 


25 miles 


8 


3 April 




9 


1-2 April 


1.8 miles 


10 


26-27 August 


10.9 miles 


11 


26 August 


10.3 miles 


12 


26 August 


6.7 miles 


13 


26 August 


4.3 miles 


14 


26 August 


1.0 miles 


15 


24 June 


1.7 miles 


16 


26 August 


2.9 miles 


17 


26 August 


3.6 miles 


18 


26 August 


4.4 miles 


19 


26 August 


6.5 miles 


20 


24-25 August 




21 


24-25 August 


3.2 miles 


22 


25 August 


0.5 miles 


23 


25 August 




24 


24-25 June 




25 


25 June 


5.4 miles 


26 


26-29 June 




27 


30 June 


15.5 miles 


28 


30 June 


16.6 miles 


29 


30 June 


14.4 miles 


30 


30 June 


10.6 miles 


31 


1-5 July 




32 


5 July 


16.6 miles 


33 


5-8 July 




34 


8 July 


11.5 miles 


35 


8 July 


9.7 miles 


36 


9-12 July 




37 


12 July 


10.8 miles 


38 


12-15 July 


0.5 miles 


39 


15 July 




40 


15 July 


4.4 miles 


41 


16-19 July 


10 miles 



SE EI Rosario; 30°0rN, 1 15°38'W 

Punta Baja; 29°58'N, 115°49'W 

SE El Rosario; 29°58'N, 1 1 5°33'W 

SE El Rosario; (RanchoSan Vicentito); 29°52'N, 115°33'W 

SE El Rosario; 29°48'N, 1 1 5°33'W 

SSE EI Rosario (Arroyo de San Fernando) ; 29°47'N, 1 15°33'W 

SSE EI Rosario (Arroyo de San Fernando) ; 29°47'N, 1 15°33'W 

San Felipe Springs (in Arroyo de San Fernando) ca. 9 miles NE 

of the arroyo-coastal road junction; 29°52'N, 1 15°26'W 
NW Puerto de San Carlos; 29°40'N, 1 15°29'W 
NE Santa Catarina Ranch; 29°53'N, 1 15°04'W 
NE Santa Catarina Ranch; 29°52'N, 1 15°04'W 
NE Santa Catarina Ranch; 29°49'N, 1 15°05'W 
NE Santa Catarina Ranch; 29°47'N, 1 15°06'W 
NE Santa Catarina Ranch; 29°44TSr, 1 15°08'W 
S Santa Catarina Ranch; 29°43'N, 1 15°08'W 
S Santa Catarina Ranch; 29°41'N, 1 15°09'W 
SW Santa Catarina Ranch; 29°40T^, 1 15°09'W 
SW Santa Catarina Ranch; 29°40'N, 1 15°09'W 
SW Santa Catarina Ranch; 29°39'N, 1 15°1 1'W 
Mesa de San Carlos (SE); 29°38'N, 115°15'W 
NE Puerto de Santa Catarina; 29=35^^1, 1 15°14'W 
NE Puerto de Santa Catarina; 29°33'N, 115°16'W 
Puerto de Santa Catarina; 29°32'N, 1 15°16'W 
Punta Canoas; 29°26'N, 115°11'W 
NE Punta Canoas; 29°26'N, 115°06'W 
Arroyo San Jose; 29° 19'N, 115°51'W 
S Arroyo de San Jose; 29°09'N, 1 14°42'W 
NW Las Palomas; 29°14'N, 114°46'W 
NW Las Palomas; 29°13'N, 114=46^ 
NW Las Palomas; 29°09'N, 114°40'W 
Las Palomas; 29°08'N, 114°33'W 
SE Las Palomas; 28°57'N, 114°29'W 
EICardon;28°56'N, 114°29'W 
SE El Cardon; 28°50'N, 114°28'W 
S Punta Prieta; 28°49'N, 1 14°10'W 
Arroyo Santo Dominguito (2.8 miles NE Santa Rosalillita); 

28°42'N, 114°15'W 
SE Santa Rosalillita; 28°37'N, 1 14°12'W 
N San Javier; 28°32'N, 1 14°05'W 
Miller's Landing; 28°28'N. 114°05'W 
S Miller's Landing; 28°25'N, 1 14°04'W 
S Jesus Maria; 28°13'N, 1 14°02'W 



240 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Martir, in the east by the peninsular divide, and in the south by the northern and north- 
western borders of the great lava plateau, but with a Pacific strip extending further south- 
ward to the vicinity of Comondu. This semi-arid region was first named the Vizcaino Desert 
District by Nelson (1921) who made a biological survey of the peninsula in 1905-1906. 
Since then it has been called the San Borja Desert (Sauer and Meigs, 1927), the Vizcaino- 
Magdalena Desert (Jaeger, 1957), the Central Desert (Aschmann, 1959), the Peninsular 
Desert (Savage, 1960), and the Vizcaino Region (Shreve and Wiggins, 1964). 

Sauer and Meigs' (1927) "San Borja Desert," based on a socio-economic division of the 
mission era, implies too restricted a geographical area, and Savage's (1960) "Peninsular 
Desert," is too inclusive. Jaeger's (1957) "Vizcaino-Magdalena Desert" is misleading. The 
Magdalena Plain, farther south on the Pacific drainage of the peninsula differs floristically 
from the Vizcaino Region (Shreve and Wiggins, 1964). I have chosen to call the area the 
"Central Desert" as suggested by Aschmann ( 1959) because it seems desirable to restrict the 
Vizcaino Desert, in accordance with local practice, to the dry coastal plain west of San Ig- 
nacio. 

CLIMATE 

Until 1963 few chmatological data were available for Baja California, most of which 
were qualitative. Important additions to these data were presented by Hastings and Turner 
(1964, 1965a) and Hastings and Humphrey (1969). 

Climatologically, the Central Desert may be classified on the origin of its climate (caus- 
ally) and on the nature of its temperature (thermally), particularly in the winter. Causally, it 
is a cool coastal phase of a subtropical desert, the Sonoran; thermally, it may be classified as 
temperate. 

The survey area is included within Meigs' (1966) "fog type" of temperate desert, and in 
the system of notation used in the UNESCO arid homoclimatic maps (Meigs, 1953) would 
be classified as Ac23— a desert climate with winter precipitation, the coldest month being 
between 10°C and 20°C (50°-68°F) mean temperature, and the warmest month between 
20°-30°C (68°-86°F) mean temperature. 

Table 2. Irregular observations (n) of wind velocity and direction. 





Wind Velocity (mph) 




Direction 






0700 


1100 


1500 


0700 


1100 


1500 


June 


1.4-5.2 


3.2-7.2 


4.8-9.8 


WNW(2) 


WNW(5) 


WNW(5) 




(5) 


(5) 


(5) 


ENE(3) 






July 


0.6-3.2 


3.0-8.2 


3.7-10.4 


W(5) 


W(14) 


W(12) 




(15) 


(18) 


(18) 


NW(2) 
WSW( 1 ) 


NW(2) 


SW(2) 


August 


0.0-2.2 


1.9-9.8 


1.3-8.6 


W(l) 


W(3) 


W(2) 




(5) 


(8) 


(7) 


SW(2) 


SW(47 


SW(2) 
S(2) 



The climate of the western coastal fringe of the Central Desert is greatly influenced by 
the cold California Current of the Pacific Ocean and the prevailing westerly winds (Table 2) 
which move layers of cool, moist air inland beneath dry descending air, producing consid- 
erable fog and cloudiness, but no precipitation, and very mild conditions. 

In our survey, onshore movement of the moist marine air, often as fog or low clouds. 



1971 



BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 



241 



72.8(62-78)5 




64.8(58-76)9 



65.5(46-85)6 



53.4(41-65)5 



48.8(26-62)5 



cr 45H 



40 



44.0(22-62)19 




41.4(29-65)7 




49.0(27-66)19 \ 49.3(31-66)3 



1 1 1 — I 1 1 I 

0700 MOO I500| 0700 1100 1500 
JUNE JULY AUGUST 



Figure 2. Relative humidity recorded in the Pacific coastal strand of the Central Desert of Baja California del 
Norte, Mexico, during June, July and August, 1969. The first figure refers to the arithmetic mean, the figures in 
parentheses to the ranges, and the last figure to the number of measurements. 

generally began in mid-afternoon when wind velocities were greatest (Table 2). The relative 
humidity increased in mid-afternoon and dropped substantially in mid-morning when the 
fog and cloud cover dissipated (Fig. 2). The frequency and extent of the fog or cloud cover 
diminished rapidly with distance from the ocean. Although Arnold (1957) reported 
frequent fogs in the Chapala Basin, about 25 miles from the Pacific, during the spring and 
summer of 1949 and 1950, fog was seldom observed during this survey more than five miles 
from the ocean. 

By late evening, along the coastal strand, visible drops of condensation formed on 
those objects that had cooled most rapidly after sunset, and by early morning substantial 
amounts of water, often 100 ml. or more, were present frequently in the depressions of rocks 
and in the axils of the basal leaves of Agave. Similarly, in the sandy soil beneath woody 
shrubs the extent of the plant drip was noticeable and, as recorded by Wiggins (1969) for 
shrubs of the Vizcaino Desert, often the subsoil was dampened to a depth of 4-5mm. Dr. 
James R. Hastings (pers. comm.) noted that on foggy mornings in the Vizcaino Region the 
ground was visibly more moist under Opuntia cholla and Machaerocereus gummosus than 
in open spaces, and that rivulets of condensate were observed running down the upper, con- 
cave surface of the leaves of Yucca valida dind Agave sp., being funneled toward the caudex. 
Hastings and Turner (1965b) suggest that some plants of the Vizcaino Region may utilize 
the fog drip as a major source of water. Certainly the common epiphte Tillandsia recurvata, 
which grows on woody shrubs and succulents, is dependent upon dew, as are many of the 
lichens of the coast such as Ramalina reticulata. Distribution of these moisture-dependent 



242 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



Vol. 16 



34.9(28.3-42.0)5 
^33.3(30'.0-40.0)5, 




41.5(30.6-50.4)19 



40.3(30.0-48.8)8 



39.2(25.8-50.0)19 

37.1/26.6-48.8)7 
33^(25.0-44.4)8 



30.1(21.6-37.0)19 



3y3.:^t23.3-42.2)7 



26.8(2_3.3 31.6)5/273^22.4-33.9)19 , ^ 
26'nr23.3-3 1.4)57 / '^6.0(19.4-35.0) 7 

24^.8(20.0-32.2)19 43,,(,9.4-32.2)7 



•^21.9(18.6-27.7)19 



9.8(17.2-21.1)5 



-OPEN 
-SHADE 



0700 1 100 ISOOI 0700 MOO 1 500 1 0700 MOO ^00 



JUNE 



JULY 



AUGUST 



Figure 3. Soil temperatures recorded at various collecting stations in the Central Desert of Baja California, 
Mexico, during June, July and August. 1969. See Fig. 2 for explanation of figures. 

plants may serve to delimit the coastal area of the Central Desert. 

As noted by McGinnies et al. ( 1968), evaporation retards heating of the soil and vege- 
tation, and may eliminate or reduce excessive heat loads, or it may keep the plant tempera- 
ture below that required for optimum growth. This factor, concomitant with the 
temperature stabilizing effect of the ocean itself and the prevalence of strong, prevailing 
onshore winds, may be important in maintaining a distinction between the east and west 
coast floras. 

The Pacitic coast of Baja California as far south as Bahi'a Magdalena, with a mean Jan- 
uary temperature above 18°C (64.4°F) and a subtropical climate, receives its maximum 
precipitation in winter (December-February), with the Central Desert receiving a winter 
average of 56mm (Hastings and Turner, 1965a). Winter storms generally cover a large area, 
are relatively gentle and may persist for days. But only in that area north of the Central 
Desert, the approximate southern limit of the Sierra San Pedro Martir, do surface and 
ground water occur with any regularity. Near the coastal strand, the only surface waters 
encountered that were readily accessible to wildlife were the springs of San Felipe (Fig. 5) 
and Las Palomas. a small stream in San Javier Arroyo (Fig. 6), and numerous "tinajas" or 
tanks in the gulches and small canyons of the foothills. 

Precipitation in fall (September-November), spring (March-May) and summer (June- 
August), in that order, is progressively less. In summer, when relative humidity tends to be 
low, rainfall is limited to thunder storms which are localized, relatively intense and of short 
duration. Rainfall from such storms was experienced on 24 June and 24 August. 



1971 



BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 



243 



45- 



40- 



^35H 

CL 
LlI 



30- 



< 



25- 



< 

UJ 



36.7(29.0-45.0)8 

34.2(26.0-42.0)19 34.0(2^:^2.0)7 

32.4(2B.p-38.5)8 
30.6(27.0-34.0)6 /, . ^ . 

/3I. 5(25.0-38.4)19 , , , 
, , , , /28.0(23.8-36.0)l9/?^-2(22.5-40.0)7 
28.6(27.4-31.0)5/ .- // 

25.0(23.3-27.2)5/27:8(22.0-34.0)19/^,52(19.0-38.0)7 

^2/3(22.8-28.4)5 /a^.8(l8.4-29.0)l9 /22.9(l9.0-28.5)7 



20-j/^9.3(l7.6-24.4)5 '20.7(18.0-24.0)19 
''18.5(17.6-20.6)5 



-OPEN 
-SHADE 



0700 MOO 1500 
JUNE 



0700 1100 1 500 1 0700 1100 1500 
JULY AUGUST 



Figure 4. The mean air temperatures recorded at various collecting stations in the Central Desert of Baia Cali- 
fornia, Mexico, during June, July and August, 1969. See Fig. 2 for explanation of figures. 

Combined mean monthly temperature data (taken from Hastings and Humphrey, 
1969) from five coastal strand localities (El Rosario, Rosarito, Vizcaino, Bahi'a Tortuga and 
Punta Abreojos) within the Central Desert and less than ten miles from the ocean show that 
the highest mean monthly temperatures occur in August and September (ca. 24.2°C) and 
the lowest in January and February (ca. I5.7°C), but less than 8.5 °C separate the mean 
temperature of winter and summer. 

Diurnal fluctuations in the summer soil and air temperatures recorded during the sur- 
vey are shown in Figures 3 and 4. In general, soil and air temperatures rose rapidly in the 
morning with the dissipation of coastal cloud or fog cover, peaked near mid-afternoon, and 
thereafter showed a gradual decrease. Shade temperature decreased less rapidly than tem- 
peratures in the open, and rose gradually from 1 100 through 1500 in June and July. 

VEGETATION 

The survey area falls within Wiggins' (1960b) Central Desert phytogeographic area, 
specifically in the district of the Vizcaino Desert Subflora. 

Characteristically, vegetation of the open coastal strand is stunted, seldom over one 
meter high, widely spaced, and lacking in species diversity. According to Wiggins (1960b) 
and Aschmann ( 1959) these characteristics are partially the result of strong, almost contin- 
uous onshore winds that release very little moisture in their passage. In areas protected 
from the direct effects of prevailing winds but still within reach of the fog and moist sea air, 
in sandy arroyo floors where the water table is near the surface, and in areas where runoff" 



244 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

concentrates at the base of slopes, the vegetation is fairly abundant. The most conspicuous 
perennial plants of the Central Desert listed by Wiggins (1960b), Shreve and Wiggins 
(1964), and Aschmann (1959), included the following: Agave spp.. Ambrosia chenopodii- 
folia. Ambrosia magdalenae. Yucca valida, Idria columnaris, Machaerocereus gummosus, 
Larrea divaricata, Lvcium californicum, A triplex polvcarpa, Viguiera deltoidea, Dudleva 
spp., Encelia spp.. Euphorbia spp., Opuntia choUa, Viscainoa geniculata, Pachycereus 
pringlei, Lophocereus schottii, Echinocereus brandegeei, Fouquieria splendens, Prosopis spp., 
Cercidium spp., Solanum spp., and Pachvcormus discolor. 

Also common in appropriate coastal strand habitats were Frankenia palmeri, A triplex 
canescens and A triplex julacea. ' 

SPECIES ACCOUNT 

AMPHIBIANS 

Bufo punctatus 

Each evening at San Javier Arroyo (Fig. 6) trilling choruses of toads were audible. On 
the evening of 14 July several pairs were observed in amplexus along a 100 meter stretch of 
a stagnant stream. The tadpoles, with well-developed hindlimbs, were collected from a 
small, shallow, algae-covered pool. A total of 83 specimens (65 adults, 18 tadpoles) were 
taken at Station 38. 

Hyla regilla deserticola 

Ten adults and two tadpoles of this race (see Jameson et al, 1966, for distribution and 
characters) were collected at San Felipe Springs (Sta. 8; Fig. 5), a small perennial spring 
marked by luxuriant vegetation consisting of cottonwoods, willows, fan palms, cirio, pita- 
haya and tules. The adults were found beneath rocks and in the grass and tules surrounding 
the main body of water, a shallow pond about five meters wide. The tadpoles were collected 
in another small pool. 

Twenty-five adults were collected from rock crevices and from beneath rocks flanking 
the stagnant San Javier stream (Sta. 38, Fig. 6). Adults called late into the evening. 

LIZARDS 

Callisaurus draconoides crinitus 

These lizards were confined to a coastal (Sta. 40; 8 specimens) and inland (Sta. 41; 28 
specimens) sand dune habitat. Many individuals were approached within several feet and 
collected by stunning them with six-inch rubberbands. 

Nine of the 18 females collected between 15-17 July had yolk-laden ovarian ova 
greater than 3mm in diameter, and four of the 18 contained oviducal ova. The mean length 
and width of ovarian ova in the left and right ovaries were 5.6(3.3-9.5)1 1 by 4.9(2.8-8.7)1 1 
and 6.2(4.7-9.0)9 by 5.7(4.5-7.8)9, respectively. Oviducal ova in the left oviduct measured 
15.2( 14.0-16.7)3 by 8.0(7.4-8.7)3 and in the right oviduct 15. 1( 13.7-17.8)7 by 9.2(7.3-1 1.0)7. 

Male crinitus average longer than females; mean lengths for 18 males and 18 females 
being 68.4mm (range 47-82mm) and 59.9mm (range 46-68mm). The mean testis size of the 
series collected in mid-July was 4.6mm(range 3. 2-5. 8mm) by 3. lmm(range 2.4-4. 0mm). The 
right testis was anterior to the left in all males examined. 

Measurements and counts of crinitus are summarized in Table 3. The distance between 
the anterior edge of the most anterior ventral tail bar and the posterior margin of the anus, a 

'A list of other dominant plants representative of the major herpetological collecting stations in this area, is filed with the Na- 
tional Auxiliary' Publication Service of the American Society for Information Service, and may be obtained by ordering NAPS 
Document 01 547 from ASIS National Auxiliary Publication Service, CCM Information Corp.. 909 Third Ave.. New York, N.Y. 
10022, remitting $5 per photocopy or $2 per microfiche copy. 



1971 



BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 



245 



measurement suggested by Dr. Benjamin Banta, readily separates crinitus from rhodos- 
tictus and appears to be much more reliable than the diagnostic characters used previously 
to separate these races (see Tevis, 1944). The number of oblique lateral bars was variable 
among the 35 crinitus examined; nine had none; three had two, two had four, and 21 had 
the three characteristic of the race. 

Except for snout-vent length, the only important sex difference was the hindlimb 
length: males, 63.7(47-75)18, females, 55.2(45-64)18. Also, females tended to lack the ob- 
lique body bars more frequently than males; eight females out of the 18 had none, whereas 
only one of 17 males lacked the bars entirely. 

Callisaurus draconoides rhodostictus 

Individuals of rhodostictus were generally confined to sandy washes and broad, sandy 
arroyos. At the most inland collecting stations, where the soil is largely decomposed granite, 




Figure 5. Station 8, San Felipe Springs (in arroyo de San Fernando), about nine miles NE of the arroyo- 
coastal road junction. Several adult Hvla regilla deserticola were collected beneath rocks and in the grass and 
tules surrounding the main body of water (see arrow): tadpoles were collected in another small pool of water not 
visible in photograph. 



246 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Table 3. Measurements and counts of Callisaurus draconoides crinitus and C. d. rhodostictus. 

crinitus rhodostictus 

Snout-vent length 64.1(46-82)36 68.9(38-85)29 

S.D. = 9.9 S.D. = 9.8 

Ratio, tail: total length 5.7(5-6) 19 5.8(4-6) 14 

S.D. = 0.4 S.D. = 0.6 

Distance between anus to most 15.9(7-26)34 3.4(1-7)29 

anterior ventral tail bar S.D. = 5.2 S.D. = 1.5 

Hindlimb length 59.4(45-75)36 64.5(32-84)17 

S.D. = 8.7 S.D. = 8.9 

Ventral body bars 2.2(0-4)35 1.8(0-2)29 

S.D. = 1.3 S.D. =: 0.6 

Ventral tail bars 6.8(0-10)20 7.6(4-10)30 

S.D. = 1.8 S.D. = 1.4 

Femoral pores' 18.2(14-22)35 13.8(11-18)27 
S.D. = 1.6 S.D. = 1.6 

'Femoral pores counted on one side only. 

rhodosticus were often observed basking during mid-day atop small rocks. 

Only four of the 17 female rhodostictus collected had enlarged yolk-laden ovarian ova, 
[mean size: 5.3(3.2-6.9)12 by 4.8(3.2-6.0)12], and none had oviducal eggs. The specimens 
with enlarged ovarian ova were collected in late August, whereas the crinitus, four of which 
had oviducal ova, were collected in mid-July. This suggests that egg laying among crinitus 
and rhodostictus ceases between the end of July and August in the Central Desert. 

Males tend to be larger than females; males had a mean snout-vent length of 75. 3(61- 
85)12 and females a mean snout-vent length of 64.3(38-75)17. The testes of eight rhodos- 
tictus averaged 4.8(3.5-6.8) 15 by 3.3(2.0-4.5)15. The right testes was anterior to the left in all 
males examined, and was usually slightly larger. 

Other counts and measurements for rhodostictus are presented in Table 3. The mean 
hindlimb length, 76.1(61-84)12 for males and 64.5(32-72)17 for females, and the mean 
snout-vent length, previously mentioned, were the only apparent quantitative differences 
between the sexes. Specimens were collected at Stations 1()(4 specimens), 11 (1), 12 (2), 13 
(2), 14(3), 15(1), 16(1), 17(3), 18(4), 19(1), 26 (4), 31 (3). 

Cnemidophorus hyperythrus schmidti 

Walker and Taylor (1968) in their prehminary treatment of the geographical variation 
among the ''hvpervthrus-like'' populations of Baja California lacked sufficient material 
from Central Baja California to determine the variation and distribution of schmidti. The 
specimens collected in this study possess a single mid-dorsal line, forked anteriorly, which is 
characteristic of schmidti (Lindsdale, 1932; Murray, 1955). Data concerning scutellation 
and pattern of those specimens are summarized and compared to similar data for hype- 
rythrus and beldingi in Table 4. 

Murray (1955) indicated that schmidti could readily be distinguished from hyperythrus, 
the southern race, by the arrangement of the mid-dorsal lines. Separation of schmidti from 
beldingi, the northern population, is based presently on the number of supraoculars sepa- 
rated from the frontal by granules and less consistently by the presence of two mid-dorsal 
stripes (Table 4). My data concerning the degree to which the supraoculars are separated 
from the frontal by granules show that this character is of little diagnostic value when con- 
sidered alone (Table 4). An apparent diagnostic difference among the three populations is 
the number of granules around mid-body, intermediate in schmidti (Table 4). 



1971 



BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 



247 



Murray (1955) stated that intergradation between schmidti and beldingi probably oc- 
curs in the vicinity of El Marmol [about 45 miles NW of Laguna Chapala (Fig. 1)], because 
individuals suggestive of intergradation have been recorded from Laguna Chapala and 
Catavina (about 30 miles NW of Laguna Chapala). Murray's primary criterion was the par- 
tial or complete separation of the second supraoculars by granules. The Catavina specimen 
(see Lindsdale, 1932) was reported by Murray to be the only one from this part of the penin- 
sula in which the second supraoculars were entirely separated by granules. I collected 15 
individuals from Stations 2 through 38 (Table 1 and Fig. 1) that show this same condition. 
One of these specimens (45554) from Station 38, about 125 miles to the south of El Marmcl, 
also has two mid-dorsal lines, more suggestive of beldingi than either of the specimens dis- 
cussed by Murray (1955). Specimens were collected at Stations 5(1), 6 (2), 7 (1), 8 (3) 15(1), 
26 (15), 31 (16), 34(1), 36 (10), 38 (3). 

Cnemidophorus labialis 

Specimens of C. labialis from the localities below fill the distributional gap of 185 miles 
between Miller's Landing and El Consuelo. Station 41, 30 miles south of Miller's Landing, 
is the southernmost collecting locality, and probably is near the species southern hmit. 

Table 4. Variation in scutellation and patterns among Baja California races of 
Cnemidophorus hyperythrus. 



beldingi 



schmidti 



hyperythrus 



Granules around midbody 

Granules separating 
dorsolateral stripes 



72.8±0.8(66-79)17' 75.2±0.6(66-83)54 
S.D. = 3.3 S.D. = 4.1 



25.4±0.4(23-30) 17' 24.2±0.3(21-29)53 

S.D. = 1.5 S.D. = 1.5 

Femoral pores (combined count) 31.9±0.5(29-37) 17' 31.5±0.4(26-39)52 

S.D. = 2.2 S.D. = 2.6 

Supraoculars (left-right) 3-4(2)',4-4(15)' 3-3(4),4-3(l),4-4(53) 



Anteriormost supraoculars 






separated from the frontal 






by granules: 






Part of third 


5* 


10=^19 


Third 




48' 14 


Part of second 


25* 


3M6 


Second 


36* 


15 


Frontoparietal 






Single 


17 


55 


Partially divided 




5 


Divided 






Number of mid-dorsal Unes 






Three 


95 




Two 


104' 


2=3 


One forked anteriorly 


46' (extent of forking, 
if present, not 




More than one-third 


stated.) 




length 




22= 10 


Less than one-third 






length 




37M6 



77.6±0.8(69-90)45' 
S.D. = 5.2 



33.6=h0.4(29-41)44' 
S.D. = 2.6 

3-3(16),3-4(3) 
4-4(26),5-4(l)^ 



28' 
443 

4* 



47' 



48= 
15^ 



'Data from Walker and Taylor (1968) 

=Data from Lindsdale (1932) 

'Combined data from Murray ( 1955) and Lindsdale (1932) 



'Data from Van Denburgh (1922) 
■Data from Burt (1931) 



248 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



The specimens, all adults, showed a daily activity cycle and occupied habitats similar 
to those previously recorded for the species (Bostic, 1968). 

Scutellation and counts for Central Desert specimens were as follows: granules around 
mid-body. 59.8±0.4(52-69)87; granules separating paravertebral stripes, 8.4±0.1(6-12)89; 
femoral pore scales, left, 13.6±0.1( 1 1-16)87, right, 13.5±:0.1( 1 1-16)78. Specimens were 
taken at Stations 2 (5), 26 (28), 28 (4), 3 1 (3), 33 (3), 36 ( 1 5), 37 (2), 4 1 (38). 




Figure 6. Station 38, San Javier Arroyo. Several Bufo pimctatus tadpoles were collected from the small, shallow 
algae-covered pool of water in the foreground. Adult B. pimctatus were particularly abundant, and many were 
observed in amplexus. A Sauromalus australis was collected from within a crevice of the granite-strewn west 
slope (see arrow). PhvUodactvlus xanti sloani were also collected beneath the exfoliating slabs of granite rock. 

Cnemidophorus tighs multiscutatus 

This species was relatively common throughout the survey area, but difficult to collect. 
Individuals were most active during the mid-day hours, when they were frequently ob- 
served foraging from shrub to shrub. They preferred the soft soil (sand and decomposed 
granite) of the washes and arroyos to the compacted, rocky soil of the marine terraces. 

Selected characters for the specimens collected are as follows: Postantebrachials gran- 
ular in all but three individuals, which have these slightly enlarged; supraorbital semi-cir- 
cles normal, except for two specimens in which they extend past the posterior margin of the 
frontal; anterior nasal not in contact with the second supralabial in all but eight lizards; 
fronto-parietal divided in all but one specimen; number of supraoculars 4-4, except for 
seven specimens which have 5-5, 4-5, or 4-3 supraoculars; granules around body, 
90.6±0.7(82-104)48; femoral pore scales (left), 20.0±0.2( 17-23)69, S.D. 1.5 1 ; femoral pore 
scales (right), 19.9±0.2( 16-23)70, S.D. 1 .58. Specimens were obtained at Stations 2 ( 1 ), 5 (4), 
8(11),9(2), 15(1), 16(1), 18(1), 19(1), 20(13), 21 (2), 26 (14), 31 (8), 33 (2), 36 (8), 38 (2). 



1971 BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 249 

Coleonyx variegatus abbot ti 

These specimens agree closely with Klauber's (1945) original description, confirm the 
presence of the race in the Central Desert, and support Klauber's (1945) tentative assign- 
ment of a damaged specimen at Calmalli, seven miles NW of El Arco, to this subspecies. 
One individual was found beneath a small slab of shale on the SW slope of a clay-like foot- 
hill (Sta. 1 ), and two were collected beneath the basal leaves of dead Agave at Station 38. 

Crotaphytus collar is 

One speciment from Station 20, an adult male, represents the first recorded occurrence 
of Crotaphytus collaris west of the peninsular divide (Van Denburgh, 1922: 109; Smith and 
Taylor, 1950:92). 

The collecting station, Mesa de San Carlos, is a broad table-topped mountain near the 
coast, which rises to an altitude of from 422 to 739 meters. The above individual was ob- 
served foraging among large basaltic rocks on the edge of the mesa at approximately 1400 
hrs. Another C. collaris was observed basking at 1730 hrs. on a small rock, part of a large 
basaltic rock outcrop, surrounded by low shrubs on the mesa proper. 

Crotaphytus wislizeni copeii 

A single juvenile from Station 20 agrees in scutellation and pattern with Banta and 
Tanner's (1968) account of the race. It was foraging in the late afternoon in a sandy wash 
thickly overgrown with xeric vegetation. 

Gerrhonotus multicarinatus ssp. 

Table 5 shows that the Central Desert specimens agree closely with G. paucicarinatus in 
degree of keeling and in some details of pigmentation. They appear more like G m. webbi in 
numbers of longitudinal dorsal scale rows, and dorsal pattern; they have an intermediate 
position between paucicarinatus and webbi in numbers of transverse dorsal scale rows, de- 
gree of keeling and numbers of keeled temporal scale rows, lateral fold pigmentation and 
ventral markings. Coloration and over-all pattern among the individuals show considerable 
variation. Some xtSQmblQ paucicarinatus and others webbi. Individual counts and measure- 
ments of the Central Desert specimens appear in Tables 6 and 7. 

The above evidence suggests intergradation between G paucicarinatus and G multi- 
carinatus. However, since a gap of about 250 miles separates these populations, it would be 
premature to make a formal nomenclatural change at this time. 

The Pacific coastal strand is suitable for the southern dispersal of G multicarinatus. 
Similarly, G. paucicarinatus, once believed to occur only in the highland area of the Cape 
Region, has now been recorded in the lowland area of the Cape (Richmond, 1965), and may 
have dispersed farther northward along the Pacific Coast where cool, moist environments 
suitable for anguids prevail. 

Savage (1960) surmised that paucicarinatus separated from multicarinatus during a 
Pleistocene glacial maximum, but whether this isolation has resulted in ecological and/or 
reproductive isolation is unknown. The Vizcaino Desert is a possible barrier preventing 
their contact. From here south through the Magdelena Plains region, coastal precipitation 
is unpredictable, and often a summer phenomenon. 

These specimens together with a specimen of G. multicarinatus ssp. from the Pacific 
coast west of Punta Prieta(Bogert and Porter, 1967: 15) are Ihe first of Gerrhonotus from the 
Central Desert. Six were collected beneath dead or partially dead Agave, and two beneath 
pieces of tin at the abandoned settlement of Las Palomas. None of the examined females, 
collected in July, had enlarged yolk-laden ova or oviducal ova, but the oviducts in all were 
highly vascularized and convoluted. 

Specimens were obtained at Stations 3 1 (1), 33 (3), 36 (3), and 38 (1). Additional speci- 



250 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



mens examined— two G. multicarinatus ssp. [SDSNH 45016, 24 December 1969, Sta. 31; 
American Museum of National History (AMNH) 75765, 22 April 1956, 5 mi. NE of Punta 
Santa Rosalia]; 18 G. paucicarinatus from the Cape Region of Baja California (SDSNH 
45006-45010,45033,45095-45098,45100-45101,45103-45106,53057-53058). 



Table 5. Comparisons between adult Gerrhonotus paucicarinatus, G. multicarinatus ssp., 
and G. multicarinatus webbi. 



Character 


G. paucicarinatus 


G. m. ssp. 


G. m. webbi^ 


Average Snout-vent length 


130 


94.6 


135(n = 35) 


Scutellation 








Dorsal Scale Rows 








Transverse 


50.7(50-51)10' 
50.1(46-54)18 


46.2(45-50)9 


41.5(38-45)44 


Longitudinal 


15.4(14,16)10' 
16.2(16,18)18 


14 


14 


Ventral Scale Rows 








Transverse 


62.7(60-64)10- 
64.1(60-67)18 


64.6(62-68)9 


63.2(60-66)44 


Longitudinal 


ir 

12.1(12,14)18 


12 


12 


Keeling 








Temporals 


None 


Upper one to two 


Upper two rows 






rows faint or none. 


or more. 


Dorsal Rows 


11.2(8-12)18 


11.4(10-14)9 


14 


Upper Arm 


None 


None 


Three rows or more. 


Lower Arm 


None 


None 


Average 2.8' 


Tail 


6-8 


6-10 


Eight plus several 
lateral rows. 


Pigmentation 








Dorsal Head Spotting 


Present (distinct) 


Present 
(distinct-faint) 


Absent (normally) 


Eye Color 


Unknown to me. 


Yellow 


Yellow 


Temporal Eye Stripe 


Distinct 


Distinct 


Faint 


Labials 


Normally distinctly 


Faintly to distinctly 


Unicolor or the 




banded with alternate 


edged with black. 


supralabials may be 




black and white 




faintly edged with 




markings. 




black. 


Body Bands 


ll.l(n= 10) when 


11.1(10-14)9; Moder- 


10.6(9-13)38; deeply 




complete, but often 


ately indented with 


indented with distinct 




bands are incomplete 


white markings on 


white markings on 




dorsolaterally. White 


fifth or sixth scale row 


fifth scale row above 




markings are reduced 


above lateral fold. The 


lateral fold and in 




laterally and usually 


white mid-dorsally is 


middle of back. 




absent mid-dorsally. 


usually indistinct. 




Lateral Fold 


Ground color 


Ground color 


Ground color 




predominates with 


predominates with 


predominates with 




narrow black lines. 


large whitish spots 


scattered white spots 






distinctly outlined and 


but no black markings. 






composed of groups 








of white scales; black 








markings when present 








faintly diffuse. 




Ventral Markings 


Along middle of 


Along middle of 


Along middle of 




longitudinal scale 


longitudinal scale 


longitudinal scale rows 




rows forming distinct 


rows forming distinct 


forming faint longi- 




longitudinal lines in 


to faint longitudinal 


tudinal lines in most. 




most. 


lines. 





'From Fitch (1938) 'From Fitch (1938) except where noted. 'From Murray (1955) 



1971 



BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 



251 



Table 6. 
Desert. 



Counts of body scales and cross bands in Gerrhonotus multicarinatus ssp. from the Central 



Catalogue 


Dorsal Scale Rows 


Number 
Keeled 


Ventral Scale Rows 


Cross 


No. 


Transverse 


Longitudinal 


Transverse 


Longitudinal 


Bands' 


45992 


45 


14 


12 


64 


12 


10 


45993 


47 


14 


14 


65 


12 


11 


45994 


45 


14 


12 


66 


12 


10 


45995 


47 


14 


12 


62 


12 


14 


45996 


45 


14 


10 


64 


12 


10 


45997 


50 


14 


11 


68 


12 


11 


45998 


47 


14 


10 


63 


12 


10 


45999 


45 


14 


10 


65 


12 


12 


46016 


45 


14 


12 


64 


12 


12 



'Partial bands not counted 



Table 7. Measurements of Gerrhonotus multicarinatus ssp. from the Central Desert. 



Catalogue 


Sex 


Collecting 
Station' 


Date 


Snout 
to vent' 


Tail 




Head 




No. 


Width 


Length 


Depth 


45992 


M 


31 


1 July 1969 


98 


Broken 


14.0 


20.0 


9.6 


46016 


M 


31 


24 Dec. 1969 


87 


Regener- 
ated 


12.4' 


19.3' 


9.0' 


45993 


M 


33 


6 July 1969 


104 


Broken 


16.5 


21.0 


12.0 


45994 


M 


33 


7 July 1969 


92 


Broken 


13.3 


19.0 


9.0 


45995 


M 


33 


7 July 1969 


100 


150(79 
whorls) 


14.6 


20.9 


11.0 


45996 


F 


36 


9 July 1969 


92 


Regener- 
ated 


11.5 


17.8 


9.8 


45997 


F 


36 


10 July 1969 


79 


Regener- 
ated 


10.9 


15.6 


6.6 


45998 


M 


36 


10 July 1969 


107 


Regener- 
ated 


17.6 


23.4 


11.0 


45999 


F 


38 


14 July 1969 


92 


Broken 


12.6 


17.9 


9.0 



'Measurements before preservation 
"See Table 1 



Petrosaurus repens 

The 10 specimens from Station 10 are the first known from the west coast of Baja CaH- 
fornia del Norte. They were initially observed basking on huge granitic boulders between 
1500 and 1830 hrs. When disturbed they usually sought refuge deep within rock fissures. 
Two individuals were smoked out and hand captured. 

None of the eight females collected on 27 August had enlarged (>3mm), yolk-laden 
ovarian or oviducal ova. All the stomachs examined contained small black seeds similar in 
appearance to those in the fruits of the barrel and fishhook cacti which occurred commonly 
in the area. Many of the stomachs also contained small amounts of other nondescript vege- 
tation and all contained the carapaces of small beetles. 

Scutellation and measurements of the specimens collected are as follows: snout-vent 
length,94.7±5.3(78-lll)6,S.D.= 13.0; head width, 16.7±0.8(14.2-19.6)7,S.D. = 2.0; femo- 
ral pore scales (combined count), 24.8±0.4(22-26)8,S.D.= 1.2; dorsals 172.4±2.2(165- 
182)7,S.D. = 5.8; head ventrals, 69.3±2.1(63-77)7,S.D. = 5.6; fourth toe lamellae, 
27.5 ±0.3(26-28)8,S.D. = 0.7. 



252 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Phrynosoma coronatum 

Two active specimens were collected on a flat, sandy substrate sparsely covered with 
low shrubs, and one was collected at 0650 hrs. by raking the sand beneath a hummock cov- 
ered with ragweed; it was relatively sluggish and made no attempt to elude capture. These 
specimens were taken at Stations 9 ( 1 ), 14 ( 1 ), and 41(1). 

Phyllodactylus xanti sloani new subspecies 

Holotype.-\d\x\i female (Fig. 7), SDSNH 45895, collected 23.5 miles SE of El Rosario 
(29°48'N, 1 15°33'W), Baja Cahfornia del Norte, Mexico, from a crevice in a block of shale 
by Thomas Cozens on 3 1 March 1969. 

Paratypes.—A\\ seventeen paratypes collected are from Baja California del Norte, 
Mexico: SDSNH 45896, Sta. 9; SDSNH 45897-45898, Sta. 25; SDSNH 45899-45900, Sta. 
26; SDSNH 45901-45907, Sta. 3 1 ; SDSNH 45908, Sta. 33; SDSNH 45909-45912, Sta. 38. 




Figure 7. Holotype (SDSNH 45895) of Phyllodactylus xanti sloani. 

Diagnosis.— This race differs from all other races, except nocticolus, confined to south- 
eastern California and the eastern desert regions of Baja California, and angulus, occurring 
on Islas Salsipuedes and San Lorenzo Island, Gulf of California, by the absence of thigh 
tubercles (see Dixon, 1969:79.1-79.2, for diagnostic accounts of the races of P. xanti); from 
angulus in larger snout-vent length (51.1mm vs. 43.8mm), less numerous mid-orbital scales 
( 1 8.0 vs. 20.5) and fewer paravertebral tubercles from axilla to groin (20.4 vs. 23.0) and from 
rear of head to base of tail (37.8 vs. 40.0); from nocticolus in less numerous longitudinal 
rows of ventral scales (27.2 vs. 35.2) and fewer tubercles in a paravertebral row between 
axilla and groin (20.4 vs. 23.0). 

Description of holotype.—Roslml twice as wide as high, its dorsal edge with two rec- 
tangular internasals, their median edges in broad contact, bordered posteriorly by five 
granules and postnasal on each side; nostril surrounded by rostral, internasal, labial, and 
two postnasals; its ventral edge in contact with labial; slight depression between internasals 
and in frontal region; 20 scales between eye and nostril; posterior dorsolateral loreals three 
to four times larger than interorbital scales; 15 scales across snout between second labials, 



1971 BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 253 

17 between third labials; 12 scales between anterior edge of orbits; 20 interorbital scales; 
eye large, contained in snout length approximately one and one-half times; eyelid with two 
rows of granules and one larger outer row of scales, the latter with seven posterior scales 
bearing spines; diameter of ear contained in diameter of eye slightly less than two times; ear 
opening not denticulate, anterior border with rounded and slightly pointed scales, posterior 
margin with smaller rounded scales; top and rear of head granular, with faintly keeled, 
larger, intermixed tubercles; 12 supralabials, seventh to center of eye; 1 1 infralabials, fifth 
to center of eye; mental lyre-shaped, length and width equal; postmentals followed by a 
transverse row of eight scales, followed by a second row of 12 smaller scales; postmentals 
contacting first labial on right and left sides. 

Dorsum with 12 longitudinal rows of enlarged, keeled, somewhat flattened tubercles, 
1 1 rows reaching head, six at base of tail; 39 paravertebral tubercles, 24 between axilla and 
groin; two median rows of enlarged tubercles separated from each other by two and three 
rows of granules; each tubercle of enlarged dorsal series separated from proceeding tu- 
bercle by one to three granules; three postanal tubercles on either side of anus, well differ- 
entiated, rounded; 35 scales across venter, 72 from gular region to anus. 

Ventral, antero-dorsal surfaces of limbs with large circular scales, postero-ventral sur- 
faces granular; lower arm and leg granular, with scattered larger, keeled tubercles inter- 
mixed; lamellae formula for left hand 7-9-10-1 1-8 (undivided 2-6-7-8-7), left foot 6-10-12- 
13-1 1 (undivided 5-8-8-12-6); claws short, tip barely visible when viewed from below; ter- 
minal pads rounded at tips; tail missing. 

Measurements in mw.— Snout- vent length 53; headwidth 10.7; head length 13.9; axilla- 
groin length 24.4. 

Color in fl/co/?o/.— Mid-dorsum ground color pinkish-tan; dorso-lateral surfaces blue- 
gray. Venter light pinkish-tan; dorsum with six reddish-brown broken crossbands, slightly 
narrower than ground color interspaces; dorsal and lateral surfaces of head spotted with 
light brown; area posterior of eye orbits, but anterior to first dorsal band, spotted with hght 
brown on a tan ground color; dorsal surfaces of limbs with brown spots; tips of enlarged 
dorsal tubercles cream, brown, or brown and cream. 

Variation.— "Ho sexual dimorphism in size, color, or pattern is evident. Counts and 
measurements are as follows: Snout-vent length 5 1.1± 0.6(32-6 1)17; enlarged series of dor- 
sal tubercles, 1 1.8±0.3(9-14)17; postmental border scales, 7.3±0.2(6-10)18; nostril to eye 
scales, 10.5±0.2(9-12)18; scales bordering internasals, 6. 8±0. 1(5-8)18; interorbital scales, 
18.0±0.3( 15-20)18; third labial scales, 16.4±0.2( 15-18)18; lamellae beneath fourth toe, 
12.5±0.2( 1 1-14)18; scales across venter, 27. 1±0. 9(21-35)17; number of paravertebral tu- 
bercles, 37.8±0.7(32-40)17; axilla to groin, 20.4±0.3( 17-24)16. Of the 18 specimens, all but 
one have the postmentals contacting two labials on each side. There are two postmentals in 
all but two individuals, which have three. The number of interorbital scales is always equal 
to or more than the number of scales across the snout between third labials. The color pat- 
tern varies from incomplete, irregular bands, and spotting to complete bands on the dorsum 
(Fig. 8). The ground color ranges from reddish-brown to gray-brown. The venter of all spec- 
imens is immaculate. 

Remarks.— ThtSQ specimens are the first of i^. xanti from the Pacific slope of the penin- 
sula (see Dixon, 1966, Fig. 1). All individuals were collected beneath exfoliating slabs and 
in fracture crevices of granite and shale, predominately the latter (see Fig. 6). This subspeci- 
fic epithet honors Allan J. Sloan, Curator of Reptiles and Amphibians, San Diego Museum 
of Natural History, whose assistance, enthusiasm and support were largely responsible for 
making this survey a reality. 

i?fl/2ge. -Known from 23.5 miles SE of El Rosario (29°48'N, 1 15°33'W) to San Javier 



254 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



(28°32'N, 1 14°05'W) on the west coast of the peninsula. 

Specimens examined.— Jht 18 specimens examined are listed under type and para- 
types. 




t^ 



4lfgS^ 





[:^i3'iio 








HLOfltf 







i.^^> 





^ 












i^j 




t.tl.'ttl 




# 



Figure 8. Dorsal variation among specimens of Phyllodactvlus xanti sloani collected along the Pacific coastal 
strand of the Central Desert of Baja California del Norte, Mexico. 

Sauromalus australis 

An adult male was collected from deep within a crevice on the afternoon of 12 July 
1969 approximately 15 yards up the steep granite-strewn west slope of Arroyo San Javier 
(Station 38; see Fig. 6). 

Despite two additional days working suitable habitats in and around the arroyo, no 
other Sauromalus were observed. That this specimen was not a "waif," however, was in- 
dicated by large amounts of dried fecal material, and by the observation of similar large 
lizards by a resident rancher, Senor Lopez of "Mi Ranchita," who stated that chuckwallas 
could be found about three miles to the east of his ranch. 



1971 BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 255 

Undoubtedly more chuckwallas will be collected in this area during a more favorable 
time of year, spring and early summer, when plant food is available and the daily tempera- 
ture not so high. I suspect that most Sauromalus in this region undergo a state of estivation 
deep within granitic fissures when the Vegetation is dormant. Plant food was also decreased 
in and around Arroyo San Javier by domestic goats. Johnson (1965) noted that almost all 
activity of a Mojave Desert population of Sauromalus obesus ceased by 1 August owing to a 
lack of food and water. 

This specimen, the first collected on the Pacific side of the Peninsula, fits the parame- 
ters of scutellation and measurements established for the species by Shaw (1945). 

The pattern and coloration of this species differ from those described for the type speci- 
men by Shaw (1945). In pattern it is hke one (SDSNH 17708) he described from La Paz, 
and in coloration it is similar to Sauromalus ater in being yellowish-black (and brown) in- 
stead of the gray characteristic of 5". aust rails. 

Sceloporus magister rufidorsum 

Sceloporus magister, difficult to collect, were most frequently associated with impene- 
trable thickets of thorn bush and pitahaya. At Station 33, a coastal sand dune habitat, they 
inhabited hummocks covered with tree sunflower (Encelia ventorum). Of the adults (snout- 
vent >93mm) collected, six were females and 13 were males, with 21 and 19 being juvenile 
female and male, respectively. Two females with snout-vent lengths of 90mm and 93mm 
contained a combined total of 13 oviducal eggs, the mean size of which was 18.0mm by 
10.0mm (range 1 1.5mm-17. 1mm by 8.8mm-12.0mm). The mean number of oviducal ova in 
the left and right oviducts was 2.5 and 4.0, respectively. 

Phelan and Brattstrom (1955), in their analysis of the variation among 5". magister pop- 
ulations, concluded that the basic diff'erences are those of coloration of the adult males, scu- 
tellation characters being so variable that they were not significant. 

Variations in scutellation and other measurements of the Central Desert specimens are 
compared (Table 8) to data provided by Phelan and Brattstrom (1955). Excluding the cir- 
cumorbital and femoral pore counts, these data fit the parameters established by Phelan 
and Brattstrom for S. m. rufidorsum. The Central Desert specimens tend to have the circum- 
orbital scales broken up into smaller units, which accounts for the greater range and mean. 
There was little consistency in color pattern among the Central Desert specimens. Of the 13 
adult males examined only one had a typical rufidorsum pattern, six had a basic rufidorsum 
pattern but lacked side bars, five had a lineatus pattern, and one had no pattern (see Phelan 
and Brattstrom, 1955, Fig. 1). Adult females showed a similar variation in pattern; juveniles 
showed a much greater one. 

In summary, dorsal patterns of adult males are so variable as to be of little diagnostic 
value. Consequently, I question the reliability of subspecific recognition based primarily on 
the dorsal pattern of adult males. Specimens were collected at Stations 2(2), 6(1), 12(1), 
15(1), 16(1), 21(3), 26(10), 31(7), 33(5), 36(8), 37(2), 38(5), 40(1),41(21). 

Sceloporus orcutti orcutti 

Seven individuals of S. orcutti were associated with large granitic rock outcrops, and 
one was collected from among the basal leaves of din Agave where it had traveled after it was 
first discovered in a thicket of thorn scrub. 

Two of three females collected on 4 and 13 July contained a total of 14 oviducal eggs, 
the mean size of which was 15.4mm x 9.5mm (range 14.2- 16.5mm x 9.1-10. 1 mm). 

Scutellation and measurements for the specimens, five females and three males, taken 
at Stations 8( 1), 10(3), 26( 1 ), 3 1( 1 ), and 38(2) are as follows: snout-vent length 83.8±4.3(67- 
I02)8,S.D.= 12.2; ratio, tail: snout-vent, 1.2±0.5(0.92-1.28)5,S.D. = 0.1; dorsal scales 
31.I±0.3(30-32)8,S.D. = 0.8; femoral pores, 13.2±0.4(12-15)8,S.D.= 1.1; gular scales. 



256 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Table 8. Scutellation and measurements of adult Sceloporus magister rufidorsum. 



Phelan and Brattstrom 
(1955) 



Central Desert Specimens 



Males 



Females 



Snout-vent length 
Ratio, tail: snout-vent 
Dorsal scales 
Femoral pores 
Gular scales 
Supralabials 
Infralabials 
Supraoculars 
Circumorbitals 
Lamellae, fourth toe 
Auricular lobules 
Ventrals 



131.0-maximum 

1.4(1.2-1.5)6 

29.8(29-31)8 

17.9(15-20)14 

15.9(15-18)8 

4.4(4-5)13 

6.2(5-7)13 

5.3(5-6)13 

5.1(3-6)14 



110.0+2.1(97-119)12 

S.D. = 7.4 

1.2±0.03(1.0-1.4)12 

S.D. = 0.1 

29.0+0.2(28-30)11 

S.D. = 0.7 

18.6±0.4(16.5-20.0)12 

S.D. = 1.5 

18.4=1:0.4(17-20)12 

S.D. = 1.2 

4.1 + 0.1(4.0-4.5)12 

S.D. = 0.2 

6.2+0.1(6.0-6.5)12 

S.D. = 0.2 

5.5 + 0.2(5-6)5 

S.D. = 0.4 

6.9+0.4(6.0-10.5)12 

S.D. = 1.3 

22.7+0.4(20-25)12 

S.D. = 1.4 

5.5+0.2(4.5-6.0)12 

S.D. = 0.7 

39.1 ±0.8(35-43) 11 

S.D. = 2.6 



96.2+1.7(93-105)6 
S.D. = 4.2 
1.3+0.04(1.2-1.3)6 
S.D. = 0.1 
29.3±0.5(28-30)3 
S.D. = 0.9 
17.5+0.5(16-19)6 
S.D. = 1.2 
18.6±0.3(17-19)6 
S.D. = 0.7 
4.1+0.1(4.0-4.5)5 
S.D. = 0.2 
6.5 + 0.1(6.0-7.0)5 
S.D. = 0.3 
5.7+0.9(5-6)5 
S.D. = 0.4 
8.1+0.9(5-11)5 
S.D. = 2.0 

22.3+0.3(21.0-23.5)6 
S.D. = 0.8 
5.5+0.3(4.5-6.0)5 
S.D. = 0.6 
40.2+0.6(39-42)6 
S.D. = 1.4 



16.8±0.4(15-18)8,S.D.= 1.0; infralabials, 5.8±0.1(5.5-6.0)8,S.D. = 0.4; supraoculars, 
5.0±0.2(4-6)8,S.D. =0.5; circumorbitals, 6.1 ±0.2(5.0-6.5)7,S.D. = 0.6; lamellae, fourth toe, 
20.6±0.9(15-23)8,S.D. = 2.4; auricular lobules, 5.6±0.2(5-6)8,S.D. = 0.5; ventrals, 
38.7±0.7(35-41)7,S.D.= 1.8. 

Urosaurus microscutatus 

All individuals were initially observed basking or foraging in rocky areas and when 
approached generally retreated to rock crevices. The collected specimens, from Stations 
10(2), 20(1), 33(1) and 38(3), represent over half of all Urosaurus observed during the 
survey. 

Uta stansburiana 

Side-blotch lizards were the most frequently observed reptile in the Central Desert. 
They occupied every conceivable habitat, and were generally the first and last reptiles ob- 
served each day. Specimens were collected at Stations 2(14), 5(2), 6(1), 8(2), 9(6), 10(7), 
14(1), 16(2), 18(0,20(8). 21(16), 23(1), 24(3), 25(1), 26(19), 28(5), 29(1), 30(1), 3 1(10), 33(7), 
36(5), 37(7), 38(4), 39(4), 40(3), and 41(46). 

Xantusia vigil is wigginsi 

This species was most commonly found beneath the basal leaves of dead Agave and 
less frequently in or under dead decaying stems of cirio and Yucca. Specimens were taken at 
stations 2(7), 5(4), 26(4), 31(8), 33(8), and 36( 1 ). 

These specimens fill the distributional gap of approximately 85 miles between the 
northermost collecting locality, 23.5 miles north of Punta Prieta, Baja California del Norte, 
recorded for this race (Savage, 1952), and a single specimen collected near El Rosario which 



1971 BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 257 

Savage stated seemed "to be nearer wigginsi than to the northern form," {X. v. vigilis). 

SNAKES 

Chilomeriscus cinctus 

An aduh male was collected at Station 38 by raking through the base of a small 
hummock of sand. A Phrvnosoma coronatum and a Sceloporus magister were collected in 
the same fashion, but beneath the sand of a larger hummock covered with ragweed. 

Counts and measurements for this individual are as follows: ventrals, 124; 
subcaudals, 25; dorsal body bands, 22; tail bands, 5; and dorsal scale rows, 15-15-13. 

Crotalus enyo envo 

A juvenile specimen was collected at Station 3 beneath a dead Agave. Scutellation 
and pattern agree with Klauber's (1931b) account of the nominal race. 

Crotalus ruber ruber 

The number of body blotches and the scale counts of these specimens fall within the 
parameters established for the race by Klauber ( 1964: Table 2:7). 

Crotalus ruber occupied a diversity of macrohabitats; one was observed in a coiled 
position about 10 yards above the high tide mark of a cobblestone beach and another in a 
coiled position beneath an ocotillo in bloom in a sandy, dune-like environment. Speci- 
mens were collected at Stations 2( 1 ), 3( 1 ), 6( 1 ), 7( 1 ), 8( 1 ), 2 1(1 ), 22( 1 ), 38( 1 ), 4 1 ( 1 ). 

Crotalus viridis helleri 

A juvenile specimen collected at Station 41 is distinctly light colored with a sharply 
defined pattern. It was observed at 0920 hrs. coiled beneath a small, sparsely branched 
ragweed shrub at the fringe of an isolated sandy dune area. 

Details of pattern and scale counts agree with those summarized by Klauber (1964, 
Table 2:7) for the race. 

Hypsiglena torquata klauberi 

An active immature female was collected at 1710 hours beneath a dead Agave in an 
eroded, sandy-bottomed wash (Sta. 2). Scutellation, coloration and pattern are similar to 
those reported by Tanner (1944) for the race. 

Lichanura roseofusca gracia 

Compendia dealing with North America reptiles list two species of Lichanura, trivir- 
gata and roseofusca, the latter species represented by two races, roseofusca and gracia. 

Klauber (1933) reported a specimen of rosy boa from Guaymas, Sonora, Mexico, that 
agreed exactly with L. trivirgata in coloration and pattern but more closely approached L. r. 
gracia in scutellation. He remarked that perhaps we might be dealing with three subspecies, 
trivigata, gracia and roseofusca. However, he did not suggest uniting the two species before 
additional material between Guaymas and southern Arizona and in central Baja California 
demonstrated intergradation. 

Since Klauber's (1933) remark, additional specimens have been collected from these 
areas, but according to Gorman (1965) we still lack a basis for uniting the two species of 
Lichanura in view of the great uniformity of pattern of trivirgata throughout its known 
range, and the absence of obvious intergrades with gracia. 

The Central Desert specimen from Station 38 is of particular interest since the locality 
is the southernmost for Lichanura in Baja California del Norte, and is only 100 miles from 
San Ignacio, the northernmost for L. trivirgata. 

The Central Desert specimens appear to agree with trivirgata in dorsal and ventral 
counts, but more closely agree with gracia in all other counts (Table 9). In pattern and color- 



258 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



ation there is close agreement with Klauber's (1931a) description of gracia . I tentatively, 
then consider these specimens to be gracia. 

One boa, a mature male, was collected in a grain field shortly after it had been killed by 
a rancher (Sta. 4), and the other, an active fem.ale, was collected in the late afternoon from 
beneath the basal leaves of Q.n Agave (Sta. 38). 

Table 9. Scale characters of Lichanura trivirgata and L. roseofusca. 





L. trivirgata 


L. roseo 


fusca'- 


Central 

Speci 

SDSNl 

45957 


Desert 
mens 
BNos. 




Gorman* 


Klauber^ 


gracia 


roseofusca 


45958 


Dorsals 

Ventrals 

Caudals 

Oculars 

Supralabials 

Infralabials 


39.2(36-41)10 
218.5(219-223)10 
45.0(42-49)10 
10.1(9-11)10 
12.8(12-14)10 
13.8(13-15)10 


41.4(40-43)7 
222.0(218-227)7 
44.0(42-46)7 
9.7(9-11)9 
12.8(12-13)7 
13.8(13-15)7 


41.3(40-43)9 
230.0(220-236)9 
46.0(42-49)9 
9.8(8-11)9 
14.1(13-15)9 
15.4(14-17)9 


40.9(35-43)38 
232.0(221-244)38 
47.0(39-51)38 
9.1(7-10)38 
14.1(12-15)38 
15.0(13-17)38 


42 
225 

46 
11-10 

15 

15 


40 
222 
43 
10 
14 
14-15 


^Data from Gorman, 1965 
'Data from Klauber, 1931 













Masticophis flagelliim piceus 

Specimens, all adult females, were taken at Stations 2(1), 9(1), and 28(1). One active 
individual was collected from within the hollow, dead stalk of an Agave at 1655 hrs. An- 
other was collected at 1500 hrs. from beneath a large shrub in a sandy, eroded arroyo. The 
most active individual was first observed in early afternoon foraging on the leeward side of 
a large inland sand dune. 

Phyllorhynchus decurtatus decurtatus 

An adult male was collected at approximately 2000 hrs. as it crossed a sandy stretch of 
road at Station 35. Scutellation and counts are as follows: caudal blotches, 7; dorsal body 
blotches, 39; ventrals, 168; caudals, 36; snout-vent length, 367; and tail length, 58. 

Pituophis melanoleucus annectens 

This adult female was killed by a farmer who saw it foraging in a grain field (Sta. 4). 

Scutellation and other counts, except for the ratio of total length to tail length, fit the 
parameters established by Klauber (1946) for the race. The aforementioned ratio is .107 
(total length 2565mm/tail length 265mm) considerably less than the . 1 55 reported by Klau- 
ber (1946) for female annectens, which he states is probably the longest tailed of all the go- 
pher snakes. 

Pituophis melanoleucus bimaris 

One specimen, an adult male from Sta. 21, was observed at 0930 hrs. as it foraged in 
a sandy area studded with pitahaya. It attempted to elude capture by retreating down a 
mammal hole. The o\htr bimaris, an active, immature female from Station 33, was collected 
from beneath the basal leaves of a dead Yucca on a coastal foothill. This individual, as in- 
dicated by the bulge in its stomach, had recently fed on a small woodrat (Neotoma). 

Salvadora hexalepis klauberi 

One specimen was collected in late afternoon while basking on a dirt road (Sta. 5). The 
other individual was collected at 1630 hrs. as it foraged in an open sandy area (Sta. 36). 

Scutellation, pattern and counts generally fit Klauber's (1946) description of the race. 
The exceptions are as follows: SDSNH 45953 has 241 ventrals, much lower than the 
range of 253-257 given by Klauber, and SDSNH 45954 has a tail-to-total-length ratio of 



1971 BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 259 

0. 168, higher than the 0. 140 reported by Klauber for the race. 
Tantillaplaniceps eiseni 

A specimen, found dead on a sandy-dirt road adjacent to a flat sparsely vegetated 
sandy area (Sta. 5) is the fifth of T! p. eiseni from the peninsula (Tanner 1966) and the first of 
Tantilla from the Pacific side of central Baja California. 

Scutellation and measurements of the specimen, an adult female, are as follows: ven- 
trals, 176; caudals, 62; ventral-caudal total, 238; total length, 211; tail length, 30; ratio of tail 
to total length, 0.142. These counts and measurements, excluding tail to total length ratio, 
fall within the range recorded by Tanner (1966) for female eiseni; but the tail to total length 
ratio of 0. 142 is considerably less than the range of 0. 1 78-0.256 reported by Tanner. Pattern 
and coloration of the specimen fit Tanner's (1966) description of the subspecies. 

DISCUSSION 

This report treats 29 species of amphibians and reptiles from the Pacific coastal strand 
of Baja California del Norte's Central Desert, including elements from three Peninsular 
faunal zones; the Californian, the Colorado Desert District, and the Cape Region. 

Only one species, Cnemidophorus labialis, may be considered to be endemic to the 
Central Desert, and only if one considers the coastal region between Arroyo Santo Tomas 
and 20 miles north of El Rosario to be Sonaran Desert. This area, based on the dominant 
forms and composition of the flora and fauna appears to be Sonoran Desert (Short and 
Crossin, 1967; Bostic, 1968). Since Shreve (1936) referred to this area as the Chaparral- 
Sonoran ecotone many workers have arbitrarily included it within the California faunal 
region. 

The relative absence of endemic forms and the lack of species diversity support, in 
part, the theory that during periods of glacial maxima the deserts of the Peninsula were aU 
but eliminated, and that reconstitution of the desert herpetofauna occurred during glacial 
minima (Savage, 1960). 

Homogeneity of habitats and the moderate chmate of the Pacific coastal strand have 
also been important factors in reducing species diversity. Savage (I960) listed 32 species 
of amphibians and reptiles comprising his central peninsular assemblage, including two 
amphibians, 16 lizards and 14 snakes. To this list may be added Hvla regilla desert icola, 
Cnemidophorus labialis, Gerrhonotus multicarinatus ssp., Lichanura roseofusca gracia, 
Tantillaplaniceps eiseni and Petrosaurus repens. 

As I have delimited the Central Desert, Savage's inclusion of Scaphiopus couchi and 
Dipsosaiirus dorsalis should be considered marginal. Both genera in Baja California del 
Norte show a decided preference for mesquite and creosote bush deserts. These plant com- 
munities are rare and never extensive in the coastal strand region. Only inland and south of 
El Arco (below 28°N. latitude), where they were prominent, did we observe Dipsosaurus 
dorsalis. 

The following snakes, included by Savage in his Peninsular Desert assemblage, were 
not recorded in the survey: Leptotvphlops humilis, Lichanura trivirgata. Arizona elegans, 
Masticophis lateralis, Sonora mosaueri and Crotalus mitchelli. As pointed out by Myers and 
Rand (1969), snakes are a herpetofaunal segment that is difficult to sample adequately, ow- 
ing in part to their lower population densities and their behavioral and structural adaptions 
designed to avoid discovery. 

None of the five species reported for the first time from the Pacific slopes of the Central 
Desert appear to be recent arrivals. They were probably overlooked during previous years 
of faunal exploration. 

Sauromalus australis and Petrosaurus repens, based upon current knowledge of their 



260 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

distribution, ecological associations, and tolerances, appear to be contiguous with the pen- 
insular populations. The scarcity of favorable habitats within the area surveyed preclude 
their occurrence elsewhere. 

Analysis of the distribution of Gerrhonotus multicarinatus spp., contrary to Savage's 
(1960) interpretation, indicates a southward expansion of its range since glacial maximum 
via the cool, moist coastal corridor. The same may be true for other temperate-tolerant 
types such as Tantilla planiceps eiseni, Coleonyx variegatus abbotti and Lichanura rose- 
ofusca gracia. The ranges of other temperate adapted forms from the Cape refugium, such 
as Gerrhonotus paucicarinatus may be expanding northward via the Pacific coastal corridor. 

The Crotaphvtus collaris of Mesa de San Carlos appear to represent an isolated popu- 
lation. The discontinuity of favorable habitat and climatic conditions within the survey 
area, excluding the Sierra Colombia with summits near 762 meters, together with the ap- 
parent distributional gap between this population and the peninsula's east coast popu- 
lations seem to support this view. 

San Carlos Mesa is about 15 miles long in a northwestern and southeastern direction 
by six miles wide and rises to an altitude of from 422 to 739 meters. The basaltic rock out- 
crops around the edge and on the top of the mesa provide suitable habitat for C. collaris. 
The mesa proper is a favorable habitat for the species. In contrast to the surrounding low- 
lands and foothills, it is subject to a greater duration and intensity of solar radiation, and 
concomitantly less frequent and shorter durations of coastal cloud cover and fog. 

Phyllodactylus xanti sloani probably represents a marginal population of the mainland 
stock that recently immigrated to the Pacific slope via the foothills of the southern extremity 
of the Sierra de San Pedro Martir occupying marginal, but suitable habitats to the north 
and south. 

ACKNOWLEDGEMENTS 

I wish to express my sincere gratitude to the Belvedere Scientific Fund of San Francisco for their financial 
support of this survey. 

I am indebted to Thomas Cozens for his field and laboratory assistance, and to Margery Stinson for her labo- 
ratory and office assistance. 

To Glen Contreras and Dennis Roberts for their able field assistance, I am especially grateful. 

For the generous help, interest and encouragement of Allan J. Sloan, Curator of Herpetology, San Diego 
Natural History Museum, I am particularly indebted. 

Special thanks are extended to Reid Moran, Curator of Botany at the SDNHM for his identification of the 
plants; to Elsie Arena for technical assistance; Bill Hite, Victor Limon and John Waldrup for field assistance; to 
Mike Langdon and DeDe Miller for their illustrations of Fig. 1 and Figs. 2,3 and 4, respectively; to Ted Karounos 
for Figs. 7 and 8; to Mr. and Mrs. Robert Eckhart for office and laboratory assistance; to Richard P. PhiUips, for his 
letters of introduction which proved to be invaluable assets; to Richard G. Zweifel, American Museum of Natural 
History, for the loan of Gerrhonotus from Baja California; to Charles Coutts and Eugene Stevens, Palomar Col- 
lege, for placing the facilities of the Life Sciences Division at my disposal; and to Leon Rector for his excellent 
preparation and maintenance of the vehicles used in the survey. 

I am particularly grateful to James R. Dixon, Richard Ethridge, Reid Moran, Clifford H. Pope, Allan J. Sloan 
and Ira L. Wiggins for their sound editorial comments and criticisms of the manuscript. 

My sincerest appreciation is extended to Mrs. Norrine Keesee and Mrs. Sophie Bartlett who typed the final 
body of the manuscript, and the tables, respectively. 

1 am also thankful for the help and cooperation of Dr. Rodolfo Hernandez Corzo, Director General de la 
Fauna Silvestre de la Secretaria de Agricultura y Ganaderia, who issued the collector's permit. 



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1957. Late pleistocene and recent changes in land forms, climate, and archaeology in central Baja Cahfornia. 
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1971 BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 261 

Aschmann, H. 

1959. The central desert of Baja California: Demography and ecology. Ibero-Amer. 42. Univ. California 
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1968. The systematics of Crolaphvtus wislizeni. the leopard lizards (Sauria: Iguanidae). Part 11. A review of 
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Dixon, J. R. 

1966. Speciation and systematics of the Gekkonid lizard genus PhvUodactvlus of the islands of the Gulf of 
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1969. PhvUodactvlus xanti. Cat. Amer. Amphibians Reptiles: 79. 1-79.2 

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Gorman, G. C. 

1965. The distribution of Lichanura trivirgata and the status of the species. Herpetologica 21(4): 283-287. 

Hastings, J. R. (Ed) and R. R. Humphrey r£J.j. 

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1964. Climatological data for Baja California. Technical reports on the meteorology and chmatology of arid 
regions, no. 14. Tucson: Univ. Arizona Atmos. Phys. 

1965a. Seasonal precipitation regimes in Baja California, Mexico. Geografiska Annaler 47 Ser. A: 204-223. 
1965b. The changing mile: an ecological study of vegetation change with time in the lower mile of an arid and 
semi-arid region. Univ. Arizona Press, Tucson. 2 1 7 p. 

Jaeger, E. C. 

1957. The North American deserts. Stanford Univ. Press. 308 p. 

Jameson, D. L., J. P. Mackey, and R. C. Richmond. 

1966. The systematics of the Pacific tree frog, Hvlaregilla. California Acad. Sci., Proc. 33( 19): 551-620. 

Johnson, S. R. 

1965. An ecological study of the chuckwalla, Sauromahis obesus Baird, in the western Mojave Desert. Amer. 
Midland Nat. 73(1): 1-29. 

Klauber. L. M. 

1931a. Anewsubspeciesof the California boa, with notes on the genus L/c/ianwra San Diego Soc. Nat. Hist., 

Trans. 6(20): 305-318. 
193 lb. Crotaliis tigris and Crotalus envo. two little known rattlesnakes of the southwest. San Diego Soc. Nat. 

Hist.. Trans. 6(24): 353-370. 
1933. Notes on Lichanura. Copeia(4): 214-215. 

1945. The geckos of the genus Coleonvx with descriptions of new subspecies. San Diego Soc. Nat. Hist., 
Trans. 10(11): 133-2''l6. 

1946. The gopher snakes of Baja California, with descriptions of new subspecies of Pitiiophis catenifer. San 
Diego Soc. Nat. Hist., Trans. 11(1): 1-40. 

1964. Rattlesnakes. Their habits, life histories, and influences on mankind. Univ. Cahfornia Press. 2 vol. 

Linsdale. J. M. 

1932. Amphibians and reptiles from Lower California. Univ. California PubL Zool. 38(6): 345-386. 

McGinnies, W. G. (Ed). B. J. Goldman (Ed), and P. Paylore (Ed). 



262 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

1968. Deserts of the world. An appraisal of research into their physical and biological environments. Univ. 
Arizona Press. 788 p. 

Meigs, P. 

1953. World distribution of arid and semiarid homoclimates. In Reviews of research on arid zone hydrology. 
Unesco, Paris Arid Zone Prog. 1 : 202-210. 

1966. Geography of coastal deserts. Unesco, Paris. Arid Zone Research 28: 140 p. 

Murray, K. F. 

1955. Herpetological collections from Baja California. Herpetologica 11:33-48. 

Myers, C. W., and A. S. Rand. 

1969. Checklist of amphibians and reptiles of Barrow Colorado Island, Panama, with comments on faunal 
change and sampUng. Smithsonian Contrib. Zool. ( 10) : 1-11. 

Nelson, E. W. 

1921. Lower California and its natural resources. Natl. Acad. Sci. 16, First Memoir. 194 p. 

Phelan, R. L. and B. H. Brattstrom. 

1955. Geographical vansition in Sceloporus magister. Herpetologica 1 1(1): 1-14. 

Richmond, N. D. 

1965. Distribution oi Gerrhonotus paucicarinatus Fitch. Copeia (3): 375. 

Sauer, C. and P. Meigs. 

1927. Lower Califomian studies. I. Site and Culture at San Fernando de Velicata. Univ. California Publ. 

Geog. 2(9): 271-302. 

Savage, J. M. 

1952. Studies on the lizard family Xantusiidae I. The systematic status of the Baja California night lizards 
allied to Xantusia vigilis, with the description of a new subspecies. Amer. Midland Nat. 48(2): 467-479. 

1960. Evolution of a peninsular herpetofauna. In symposium: The biogeography of Baja California and adja- 
cent seas. Syst. Zool. 9(3-4): 184-212. 

Shaw, C. E. 

1945. The chuckwallas, genus Sawrowa/w.?. San Diego Soc. Nat. Hist., Trans. 10( 15): 269-306. 

Short, L. L., Jr., and R. Crossin. 

1967. Notes on the avifauna of northwestern Baja California. San Diego Soc. Nat. Hist., Trans. 14(20): 281- 
300. 

Shreve, F. 

1936. The transition from desert to chaparral in Baja California. Madrono 3: 357-264. 
1942. The desert vegetation of North America. Bot. Rev. 8(4): 195-246. 

Shreve, F. and I. L. Wiggins. 

1964. Vegetation and flora of the Sonoran Desert. Stanford, Stanford Univ. Press. I: 1-840. 

Smith, H. M. and E. H. Taylor. 

1950. An annotated checklist and key to the reptiles of Mexico exclusive of the snakes. U.S. Natl. Mus. Bull. 
199: 1-253. 

Tanner, W. W. 

1944. A taxonomic study of the genus Hypsiglena. Great Basin Nat. 5(3-4): 25-92. 

1966. The night snakes of Baja California. San Diego Soc. Nat. Hist., Trans. 14(15): 189-196. 

Tevis, L. 

1944. Herpetological notes from Lower Cahfomia. Copeia ( 1): 6- 18. 

Van Denburgh, J. 

1922. The reptiles of western North America. Occ. Papers Cahfomia Acad. Sci. (10): 1-1028. 

Walker,;. M. 

1966. Morphology, habitat and behavior of the teiid lizard. Cnemidophorus labialis. Copeia (4): 644-650. 

Walker, J. M. and H. L. Taylor. 

1968. Geographical variation in the Teiid lizard Cnemidophorus hyperythnis. I. The caeruleus-Mke subspecies. 
Amer. Midland Nat. 80( ! ) : 1 -27. 

Wiggins, I. L. 

1960a. Investigationsin the natural history of Baja California. California Acad. Sci., Proc.30(l): 1-45. 
1960b. The origin and relationships of land flora. In symposium: The biogeography of Baja California and 
adjacent seas. Syst. Zool. 9(3-4): 148-165. 



1971 BOSTIC: BAJA CALIFORNIA HERPETOFAUNA 263 

1969. Observations on the Vizcaino Desert and its biota. California Acad. Sci., Proc, 4th series 36(1 !)• 317- 
346. 



Life Sciences Department, Palomar College, San Marcos, California 92069 




i/lliis. CO.viK ZCCL. 
LIBRARY 

FEB 1 8 1972 

HARVARD 
UNIVERSITY 



A NEW GENUS OF CHTHAMALIDAE 
(CIRRIPEDIA) FROM THE SOUTHEASTERN 
PACIFIC ISLAND OF SAN AMBROSIO 



ARNOLD ROSS 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 

VOL. 16, NO. 1 1 26 OCTOBER 1971 



A NEW GENUS OF CHTHAMALIDAE 
(CIRRIPEDIA) FROM THE SOUTHEASTERN 
PACIFIC ISLAND OF SAN AMBROSIO 

ARNOLD ROSS 



ABSTRACT .—Jehlius gilmorei n. gen., n. sp. is proposed for a chthamalid apparently endemic to Isla San 
Ambrosio, a volcanic island about 800 km west of Chanaral, Chile. This new barnacle has a grade of shell 
construction transitional between 6 and 4 plates. 

From 15 May through 6 July 1970 the U.S. Antarctic Research Program (USARP) 
trawler Hero cruised the southwest and central coasts of Chile, and visited Isla Robinson 
Crusoe of the Juan Fernandez group, and Islas San Ambrosio and San Felix of the Des- 
venturados group. The cruise objectives were to obtain data on marine mammals and birds. 
But at my request barnacles were collected as opportunity permitted. Gilmore (1971: 10) 
gave a preliminary report of this cruise. 

The Islas de los Desventurados include the oceanic islands of San Ambrosio and San 
Felix, together with a lesser rock, Gonzalez, at about 26° south and 80° west, or approx- 
imately 800 km off the coast of Chanaral, Chile (Fig. 1). These volcanic islands rise some 
4000m from the sea floor. The surface waters here have a salinity of about 34.5% and an 
average surface temperature during February-March of 20°-21° C, and during July-Sep- 
tember of 17°-18° C (Meteorological Office, 1956; Murphy, 1936: 104; Wyrtki, 1966: 40). 
San Ambrosio, type locality for the new chthamalid described herein, is about 4 km long 
and 1 km wide with an estimated maximum elevation of 480 m (Fig. 2). 

PREVIOUS STUDIES ON THE BIOTA 

The biota of the Desventurados islands remains poorly known owing to their relative 
inaccessibility and the lack of good landing sites (Fig. 3; see Douglas, 1970: 345). On the 
basis of a short visit, Bahamonde N. (1966) presented a popular, broad, and general account 
of the biota. 

Studies on the flora were published by Johnston (1935) and by Skottsberg (1937, 1952), 
both of whom Usted references to earlier studies. The avifauna was treated by Murphy 
(1936) and by Johnson (1965, 1967), who also cited earlier references. Allen (1899) dis- 
cussed briefly the hunting and virtual extermination of fur seals {Arctocephalus) in rook- 
eries on the two major islands (see also Gilmore, 1971: 10), and Kellogg (1943: 306) pres- 
ented data on the size of the catch during the early years of American sealing in these wa- 
ters. Other studies are those by Serafy (1971: 165) who described a new Clypeaster from San 
Felix, and by McLean (1970: 362), who described two new fissurelUd gastropods. 

The only mention of the crustacean fauna of the island with which I am familiar is by 
Bahamonde N. (1966: 7) who stated "En la zona supramareal hay una franja muy nitida de 
Cirripedos. En sus cercanias es posible capturar ejemplares de la 'jaiba corredora' {Lepto- 
grapsus variegatus), designada por Philippi como Grapsus obscurus, por su coloracion. Alh 
es muy abundante. Tambien se halla habitualmente en las pozas profundas ejemplares de 
Rhynchocinetes balsii y en las areas en que predomina las algas de los generos Padina y 
Corallina se obtuvieron individuos de Plagusia chabrus.'' 

CHTHAMALID COLONIZATION OF ISLA SAN AMBROSIO 
Under the influence of the west wind drift, South Pacific Temperate Water flows east 

SAN DIEGO SOC. NAT. HIST., TRANS. 16(11): 265-278, 26 OCTOBER 1971 



266 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



1^ 

05 



80° W 



1^ 
55 



Rocas Catedral de 
Peterborough 



San Felix 




O Islo 



te Gonzalez 



San Ambrosio 



Roca Conico 




•Bahi'a Covadonga 



/^ ' Roca Mas Afuere 



Roca Bass 



05 
I 



80 W 
_| 



SCALE 1250000 



Figure \. Map showing position of Isla San Ambrosio relative to other islands in the Desventurados group, 
Chile. 

toward South America (Wyrtki, 1968: 131). Near Chile at about 50° S this water mass di- 
vides, one branch turning south and eastward around the tip of South America, the other 
flowing northward along the coast as the Peru Current ( = Humboldt Current) or the Peru- 
Chile Current System. The offshore Desventurados Islands are under the influence of this 
current system. The Peru Current extends as far north as Ecuador and then swings west just 
south of the Equator to become part of the South Equatorial Current. The northward flow 
of the Peru Current, generally at 25° S, is divided into two components, the Peru Coastal 
Current and the Peru Oceanic Current, between which is a southward moving subsurface 
current, the Peru Countercurrent, which carries equatorial subsurface water as far as 22° S 
(Wyrtki, 1966: 59; 1968: 121). 

The prevailing north-flowing currents argue for colonization of San Ambrosio from 
the southeast, much as the biota of the Juan Fernandez Islands, in the main, also appears to 
have been derived from South America. I have discounted a direct Australia-New Zealand 
origin of the Desventurados chthamalid largely because of the vast distance separating the 
two regions, the apparent absence of any living or extinct populations of chthamahds in the 
region between, and because the temperate Southeast Pacific chthamalids have their great- 
est affinity with the Tropical American fauna (ZuUo, 1966: 142). Elminius and Austroba- 
lanus in the southeastern Pacific, although seemingly good indicators of biogeographical 
affinities, are two groups that remain poorly known (the type species of Austrobalanus is 
apparently a six-plated tetraclitid and the remainder true balanids; Elminius until recently 
contained two species referable to the tetraclitid Epopella and the remaining two or three 
widely separated species offer no clues as to their origin [Ross, 1970: 9]). 

Based on morphological and hydrographic evidence, this new chthamalid probably 
evolved from or shared a common ancestry with Chthamalus cirratus Darwin, 1854, which 



1971 



ROSS: A NEW GENUS OF CHTHAMALIDAE 



267 




Figure 2. View from the northwest of Isla San Ambrosio. Small prominence to the right of San Ambrosio is 
Roca Conico. Photo by R. M. Gilmore. 

occurs commonly along the west coast of South America from the Chonos Archipelago in 
Chile (about 45° S) to Guayaquil, Ecuador (2° 13' S) (Pilsbry, 1916: 321; Nilsson-Cantell, 
1957: 11). 

Three possible modes of colonization are offered in what I believe to be increasing 
probability, 1) introduction by or through an agency of man, 2) larval colonization, and 3) 
adult colonization by natural drift or rafting. I have discounted the first because Chtha- 
malus and its derivatives are essentially shore barnacles, although they are known to foul 
marine structures. Also, the evolutionary state of this new species argues for colonization 
prior to the origin of man in the new world. I also doubt that the islands were colonized by 
larvae, because the nauplii of Chthamalus and other balanomorphs in general lack the long 
tomentose flotation setae characteristic of pelagic species, and because the nauplii of inter- 
tidal barnacles probably remain in the plankton less than two weeks, which is apparently 
not long enough to reach San Ambrosio. The efficacy of natural rafting is well documented 
in the Hterature, and it appears most probable that colonization of San Ambrosio was ef- 
fected by rafting. 

As Crisp and Southward concluded (1953: 209), even narrow seas pose a barrier to 
animals that are predominantly intertidal. The relatively small size of the two major islands 
in the Desventurados Group (San Ambrosio— 4 km long, 1 km wide; San Felix— 3 km long, 
1 km wide), and their great distance from the South American mainland, would tend to 
preclude repetitive colonization from the mainland. Many workers have remarked that in 
order to estabUsh a viable population some minimum density is required. However, since 
there is good evidence that many species of Chthamalus are readily capable of self fertiliza- 
tion under certain conditions (Barnes and Barnes, 1958: 550), the initial propagule could 
have been only a single individual. 



268 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 3. View of landing site at Bahi'a Covadonga, Isla San Ambrosio. The two wooden shacks are used by 
transient lobster fishermen. Photo by R. M. Gilmore. 



1971 ROSS: A NEW GENUS OF CHTHAMALIDAE 269 

SYSTEMATICS 

Family Chthamalidae Darwin, 1854 

Remarks —The new taxa described below are assigned to this family, which was diag- 
nosed recently by Newman, Zullo, and Withers (1969: 283) and emended subsequently by 
Newman and Ross (1971: 139). The assignment of genera to this family differs in several 
details between that of the above workers and that proposed by Utinomi (1968: 36). Type 
Genus— Chthamalus Ranzani, 1817 (for Lepas stellatus Poh, 1791, by original designation, 
Recent, Bay of Naples, Italy). 

KEY TO GENERA OF LIVING CHTHAMALIDAE 

1. Shell composed of 8 parietal plates 2 

1. Shell composed of 6 or 4 parietal plates 5 

2. Shell with 2 or more whorls of basal plates 3 

2. Shell without whorls of basal plates 4 

3. Shell with 6-8 whorls of basal plates; caudal 

appendages lacking (1 sp.) Catomerus 

3. Shell with 2-6 whorls of basal plates; caudal 

appendages present (2 spp.) Catophragmus 

4. Shell in young individuals with eight plates, in older 
individuals with 6 or 4; mandible quadridentoid; 
cirrus III more like cirrus II than IV; caudal 

appendages present (8 spp.) Pachylasma 

4. Shell never with fewer than 8 plates, mandible 
tridentoid; cirrus III more like cirrus IV than II, 

caudal appendages lacking (3 spp.) Octomeris 

5. Shell with a single whorl of basal plates (1 sp.) Chionelasmus 

5. Shell without whorls of basal plates 6 

6. Mandible tridentoid (12 spp.) Euraphia 

6. Mandible quadridentoid 7 

7. Shell with inflected basal rim (1 spp.) Tetrachthamalus 

7. Shell without inflected basal rim 8 

8. Shell of adult with 6 wall plates (13 spp.) Chthamalus 

8. Shell of adult with 4 wall plates, or transitional 

between 6 and 4 wall plates 9 

9. Wall plates coalescing in juvenile stage; scutum with 
adductor ridge; anterior cirri armed with grapple-like 

spines (3 spp.) Chamaesipho 

9. Wall plates coalescing in adult stage; scutum without 
adductor ridge; anterior cirri lacking grapple-like 
spines (1 sp.) Jehlius 

Jehlius n. gen. 

Definition.— SheW of adult in transitional stage between 6 and 4 plates; reduction in 
number of plates by fusion rather than exclusion; in 4 plated stage wall plates not second- 
arily coalesced; plates disposed asymmetrically or symmetrically; fusion pattern variable 
throughout population; compartments lacking radii and inflected basal rim; basis mem- 
branous; scutum with well defined depression for adductor muscle, but no adductor ridge; 
cirrus III structurally and probably functionally more similar to cirri IV-VI than to cirrus II; 



270 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



cirrus II lacking grapple-like spines; caudal appendages lacking; mandible with four teeth, 
basal comb, and spine-like inferior angle. 

Type species.— J ehlius gilmorei new species. 

Remarks.— J ehlius is unique in that the parietal plates are not always symmetrically 
disposed and that the pattern of fusion of the plates has not become fixed at least within the 
few specimens available for study (Fig. 4). Also, shell development is obviously transitional 
between six and four plates, and in the two specimens with only four plates there is no in- 
dication whatsoever that these plates will secondarily coalesce. 

The shell of Chamaesipho is fundamentally composed of six plates, rostrum, carina, 
and paired rostrolaterals and laterals, but the genus is regarded as tetramerous (see Moore, 
1944; Pope, 1965; Newman, ZuUo and Withers, 1969). The six sutures separating these 
plates in C. columna are rarely seen in individuals beyond 2 mm in rostro-carinal diameter 
and occasionally they are obliterated in individuals as small as 0.5 mm in diameter (Moore, 
1944: 317). In C bninnea, on the other hand, the sutures delimiting the plates are no longer 
visible by the time individuals reach 6 mm in diameter (Moore, 1944). 

In both species o^ Chamaesipho mentioned above, the rostrolaterals are united with the 
laterals. In specimen 1 ofJehlius (see Fig. 4), the arrangement of the wall plates appears to 
be the same as in Chamaesipho columna. In specimen 3, the right lateral is fused and sec- 
ondarily coalesced in part with the carina, but the left lateral is fused with the rostrolateral. 
In specimen 2 the right lateral and rostrolateral are fused with the rostrum, and the left 



Pachylasma Tetrachthamalus Chamaesipho 



(^ O B O 




Pac 


hylasrra 


Oc 


tomens 


Catt 


phragmus' 


I 

X", 


) 



CHTHAMALIDAE 




e) (J o 



Figure 4. Plan views of wall construction in the Chthamalidae. Numerals at left indicate grades of decreasing 
complexity. Shell outlines ofJehlius on right side are camera lucida drawings of the internal surface showing de- 
gree of development of sutures, which are not readily discernible on external surface of shell (right side of shell 
is on left side in drawing). Number in center of orifice refers to number in plan view below. Specimen No. 3 is 
holotype, S.D.S.N.H. No. 4003/3. 



1971 



ROSS: A NEW GENUS OF CHTHAMALIDAE 



271 



rostrolateral and lateral remain separate. Specimen 4 is the most unusual of the lot. It has 
one major suture, between the rostrum and the right rostrolateral, and all of the other plates 
are partially coalesced (Fig. 5). Aside from the unusual arrangement of the wall plates there 
is nothing to suggest that the shells are pathologically malformed. 

Jehlius also differs from Chamaesipho in the articulation of the opercular plates. The 
junction between the scutum and tergum on each side, when viewed internally, in Chamae- 
sipho takes the form of the Greek letter omega, but in Jehlius it is simpler and only slightly 
sinuous. Jehlius also differs in that cirri I-III lack the grapple-like spines and the scutum 
lacks an adductor ridge but has a well defined deep pit for the insertion of the adductor 
muscle (Fig. 6). 

Jehlius obviously is derived from an Eastern Pacific stock of Chthamalus, whereas 
Chamaesipho probably was derived from an Indo-Pacific stock. Furthermore, Chamaesipho 
is restricted to the austral region and the probability of penetrating the East Pacific barrier 
is remote. 

Tetrachthamalus, also a genus with four plates that evolved from Chthamalus, differs 
from Jehlius in that the rostrolaterals are fused with the rostrum to form a tripartite plate, 
and during the ontogeny of individuals in this genus the four plates coalesce. 

Etymology— Earned for Dr. Joseph R. Jehl, Jr., San Diego Museum of Natural His- 
tory, longtime friend and colleague, and collector of the specimens reported on herein. 

Jehlius gilmorei n. sp. 

Diagnosis— Crest of labrum armed with 50-60 simple conical teeth; cutting edge of 
maxilla II with 10-13 long spines in medial cluster; intermediate articles of posterior cirri, 
which have rami of equal length, bear 5 pairs of setae; basal segment of anterior ramus of 
cirrus I armed with stout spines. 

Description.— Shell white or grayish-white, low conic, broadly ovate to subcircular in 
outline; basal portion of compartments ribbed and periphery of shell irregular or strongly 
toothed (Fig. 5); upper portion of external surface corroded, exfoliating; aperture relatively 
large owing to corrosion; radii lacking; sheath less than Va height of compartments, basal 
margin not depending; surface below sheath smooth. Basis membranous. 




Figure 5. Jehlius gilmorei n. gen., n. sp. External and internal views, respectively, of shell. Paratype, S D.S.N.H. 
No. 4004/4; actual rostro-carinal diameter, 8. 1 mm. 



272 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Scutum transversely elongated (Fig. 6); length about '/s greater than height; external 
surface poorly preserved, exfoliating; only last 3-4 newly formed growth ridges preserved 
along basal margin of plate; articular ridge poorly differentiated from articular surface; ad- 
ductor ridge absent; depression for adductor muscle deep, well delimited; depression for 
lateral depressor muscle deep, well defined, crossed by 3-4 septa; depression for rostral 
depressor muscle commonly shallow, poorly delimited; apical portion of plate lacking 
ridges, crests, or pits. 

Tergum higher than wide (Fig. 6); external surface poorly preserved, exfoliating; ex- 
ternal longitudinal furrow apparently lacking; spur rounded or pointed distally, and not 
distinctly separated from articular margin; articular ridge low, poorly developed; parallel 
and immediately adjacent to articular ridge there is a row of shallow, oblong pits; there are 
2 prominent and 1-2 lesser crests for the insertion of the lateral depressor muscle; apical 
portion of plate either slightly pitted or roughened. 

Measurements of the holotype (in mm) are as follows: rostro-carinal diameter 9.7. lat- 
eral diameter 9.1, height 5.1, rostro-carinal diameter of orifice 5.2, height of scutum 3.0, 
width of scutum 3.9, height of tergum 2.8, width of tergum 2.0. The range in rostro-carinal 
diameter of the four specimens is 8.1-10.1 (x = 9.2), and the range in height is 2.6-5.1 (x = 
3.3). 







Figure 6. Opercular plates of Jehlius gilmorei n. gen., n. sp. External views of scutum and tergum. respectively 
(top row), and internal views of scutum and tergum, respectively (bottom row). Paratype, S.D.S.N.H. No. 
4004/2. Drawings by Anthony D'Attilio. 



1971 



ROSS: A NEW GENUS OF CHTHAMALIDAE 



273 




Figure 7. Jehlius gilmorei n. gen., n. sp. a, right mandible; b, left mandible: c, maxilla II; d, intermediate articles 
of cirrus VI; e, crest of labrum; f, maxilla I. Holotype, S.D.S.N.H. no. 4003/3. 

Crest of labrum thin, with broad U-shaped medial notch toothed its whole width; teeth 
50-60, close spaced, simple, conical; bristles behind and parallel to teeth along crest short 
and densely packed (Fig. 7). Palps elongate, rounded distally, the basal margin convex and 
free of setae; superior margin densely clothed with coarsely bipinnate, long, slender setae; 
setae on distal extremity longer than on proximal, and finely bipinnate. Cutting edge of 
mandible armed with 4 teeth, basal comb, and spine-like inferior angle; teeth 2-4 bicuspate; 
comb between tooth 4 and inferior angle with 50-60 acicular teeth (Fig. 7). Maxilla I with 2 
long stout and 1-2 shorter stout spines above subapical notch, 4-5 short slender spines in 
notch, 10-13 long stout spines medially, 14-20 slender spines in basal cluster (Fig. 7). Cut- 
ting edge of maxilla II distinctly bilobate; setae along apical margin long, finely bipinnate, 
setae progressively shorter toward notch; notch free of setae; setae on basal lobe finely bi- 
pinnate (Fig. 7). 

Anterior ramus of cirrus I about 1/5 longer than posterior ramus; intermediate articles 
of both rami about twice as broad as high; proximal segment of anterior ramus armed with 
5 or 6 short, stout spines along posterior border (Fig. 8); 1 row of coarse ctenae present on 
lateral face of segments of each ramus immediately below articulation; ctenae better devel- 
oped on posterior ramus than on anterior ramus; setae on both rami bipinnate. Rami of 
cirrus II essentially equal in length and about same length as rami of cirrus I; 1 row of coarse 
ctenae present on lateral face of segments of both rami immediately below articulation; 
setae on both rami bipectinate. Cirri III-VI essentially equal in length and with equal 
rami; 1-2 long slender, and 1-2 shorter slender setae at each articulation along greater cur- 



274 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




0.^ nini 




ANTERIOR RAMUS 



T,'' 



y 



Y'\ 



f 



k/ 



n.e 5 5 5 6 8 

I II III IV V VI 



mean 

no. 



POSTERIOR RAMUS 



;-- 



/ 



/ 






1 II III IV V 



5 

VI 




Figure 8. Outline drawings of cirri I-VI (setae omitted; paratype, S.D.S.N.H. No. 4004/2) and summary of data 
on cirral counts for the holotype and two paratypes. 

vature of intermediate articles; 1 row of ctenae on lateral face of intermediate segments 
below articulation; setation ctenopod, with 5 pairs of setae on each intermediate segment; 
at base of each pair of setae there are 2-3 short, slender setae. Cirral counts for specimens in 
the type lot are summarized in Figure 8. 

Intromittent organ annulated throughout its length, and sparsely covered with short, 
slender bristles; distal extremity bilobed and each lobe bearing about 15 or 16 short, slender 
setae. 

Type Locality— On northeast coast, just west of Bahia Covadonga, Isla San Ambrosio, 
Islas de los Desventurados, Chile, approximately 26° 20' 15" S., 79° 15' 45" W., I. M. W. SG 
17; intertidal on volcanic rock; J. R. Jehl, Jr. coll., 27 June 1970; USARP cruise 70-3. 

Disposition of types.— The holotype and three paratypes are housed in the collections of 
the San Diego Society of Natural History, Marine Invertebrate catalogue numbers 4003/3 
and 4004/ 1, 4004/2 and 4004/4 respectively. 

Etymology.— The specific epithet honors Dr. Raymond M. Gilmore, Research Associ- 
ate, San Diego Natural History Museum, and chief scientist aboard the trawler Hero during 
USARP cruise 70-3. 



INTRAFAMILIAL RELATIONSHIPS 
Four families are presently recognized within the suborder Balanomorpha, namely 



1971 ROSS: A NEW GENUS OF CHTHAMALIDAE 275 

Chthamalidae, Bathylasmatidae, Tetraclitidae, and Balanidae (see Newman and Ross, 
1971: 137). Of these, the Chthamalidae are more generalized structurally and appear in 
the fossil record before any of the others. 

Within the Balanomorpha the evolutionary history has been one of reduction in the 
number of compartments composing the shell (Pilsbry, 1916: 291; Withers, 1928: 46). In 
the Chthamalidae this reduction has been accompanied further by structural modification 
of the mouth parts and cirri for feeding (Zullo, 1963: 190). 

Based on the probable mode of reduction in the number of shell elements, two Hne- 
ages are evident in the Chthamalidae. In the first, consisting solely of Pachvlasma, the 
shell initially contains 8 plates, including rostrum, carina, and paired rostrolaterals, later- 
als, and carinolaterals. Subsequently, the rostrolaterals coalesce with the rostrum forming 
a tripartite plate, and the carinolaterals may coalesce with the laterals yielding a shell of 
only 4 plates (Fig. 4). 

The second lineage {Octomeris-Chthamahis group) includes the remaining genera 
(Fig. 4; see Newman and Ross, 1971: 141; cf. Utinomi, 1968: 36). Of these, Catophragmus 
(including the subgenera Catomerus and Pachvdiadema) and Octomeris have the same 
number and arrangement of the plates as does Pachvlasma. Early in the evolution of this 
lineage, the number of shell elements was reduced through eUmination or exclusion since 
Chthamalus has only six wall plates (rostrum, carina, and paired rostrolaterals and later- 
als), the carino-laterals lacking. The small size of the carina and the presence of alae point 
to reduction by exclusion. From Chthamalus a further reduction in the number of wall 
plates, by fusion, is evident in Tetrachthamalus and Chamaesipho. In Tetrachthamahis the 
rostrolaterals are fused with the rostrum, as shown by the size of the composite plate and 
by the fact that it has radii, thus forming a tripartite plate essentially similar to that in 
Pachvlasma and the bathylasmatid Tessarelasma. In Chamaesipho columna and C. 
bnmnea the shell initially contains six plates; the rostrolaterals fuse with the laterals 
(Withers, 1928: 45; Moore, 1944: 324) rather than with the rostrum as in Tetrachtha- 
malus. By the time individuals of C. columna reach a rostrocarinal diameter of 2 mm and 
individuals of C. bnmnea a diameter of 5-6 mm, all the plates coalesce secondarily, and 
the sutures are obliterated. In adults of Tetrachthamalus oblitteratus, which reach a rostro- 
carinal diameter probably not much greater than 6 mm, the sutures are commonly dis- 
tinct; but then coalescence occurs, and remnants of these sutures can be observed in the 
sheath (Newman, 1967: 427). 

In all chthamalids with 6 or 4 plates fusion of shell elements and their subsequent 
coalescence proceeds in a uniform manner. To judge from the specimens available, this 
apparently is just the opposite of what takes place in Jehlius (Fig. 4). Although two speci- 
mens of Jehlius have in part attained a grade of construction comparable with that found 
in 4-plated individuals of Chamaesipho, two specimens are effectively intermediate be- 
tween six and four plates. In the two specimens that have attained a 4-plated grade of 
construction, there is no secondary coalescence and obliteration of the sutures uniting 
these wall plates. 

In his classification of the chthamalids Zullo (1963:190) stressed the modification in 
mandibular and cirral structures attending the reduction in number of the wall plates. In 
Octomeris, Chthamalus, Chamaesipho, Tetrachthamalus and Jehlius the mandible is char- 
acteristically quadridentoid, but in Catophragmus, Catomerus, Chionelasmus, Euraphia 
and Pachvlasma it is tridentoid. In the Octomeris-Chthamalus lineage the third cirrus is 
relatively unmodified; but in the Pachvlasma lineage, feeding adaptations involve the 
modification of cirrus III as a mouth appendage, such as is found in the balanids. 

Pachvdiadema from the Cretaceous (U. Senon.) of Sweden is the oldest known 



276 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

chthamalid with eight wall plates and at least two whorls of imbricating basal plates. The 
number and arrangement of wall plates, simple opercular valves, caudal appendages, and 
unmodified third cirrus all tend to link Pachvdiadema with the scalpellid lepadomorphs 
(Newman, ZuUo, and Withers, 1969: R 269). ' 

Pachvdiadema is probably ancestral to Catomerus (Withers, 1935: 390; Pope, 1965: 
15), which also possesses eight wall plates and several whorls of imbricating plates. Ca- 
tophragamus also may have been derived from Pachvdiadema, or possibly from Cato- 
merus. The presence of caudal appendages in Catophragamus suggests derivation from 
Pachvdiadema rather than from Catomerus which lacks these appendages. Chionelasmus 
with but six wall plates (carinolaterals lacking) and a single whorl of basal plates, and 
with caudal appendages, is probably an off-shoot from Catophragmus. 

Octomeris lacks the basal whorls of plates and caudal appendages, and hence is prob- 
ably derived from Catomerus, which also lacks caudal appendages, and the articulation of 
the opercular plates is simple rather than complex as it is in Catophragmus. From Octo- 
meris it is a single step, through loss of the carinolaterals, to Chthamahts and Euraphia, 
which probably share a common ancestry. However, Euraphia has retained the lepa- 
domorph or early chthamalid tridentoid mandible whereas Chthamahts has evolved the 
quadridentoid mandible with a basal comb. 

Chamaesipho evolved from Chthamahts (Newman, 1967: 431), and probably rather 
recently. Although young individuals of Chamaesipho brumiea and C. cohunna develop ros- 
trolateral plates initially, these soon fuse with the laterals forming a shell with only four 
plates; later the sutures coalesce, and are obliterated. In Euraphia the plates apparently 
never coalesce but they do develop an inflected basal rim (see Newman, 1961). Tet- 
rachthamahis is also an offshoot from Chthamalus (Newman, 1967: 431) but apparently of 
greater antiquity than Chamaesipho. In Tetrachthamahts there is no evidence in the 
ontogeny of a stage having six plates as in Chamaesipho, but as in Chamaesipho the plates 
eventually coalesce. The wall plates in Tetrachthamahis, unlike those in Chamaesipho and 
Jehlius, develop an inflected basal rim. Jehlius is apparently the most recent offshoot from 
Chthamahis, and is most closely related to C cirratus. 

ACKNOWLEDGMENTS 

For the loan or gift of comparative materials I thank Elizabeth Pope, The Australian Museum, Brian Fos- 
ter, University of Auckland, William A. Newman, Scripps Institution of Oceanography (S.I.O.), and Meredith 
L. Jones, Smithsonian Institution. I thank my personal physician Dr. Wayne L. Heath and his assistant Mrs. Su- 
san D. Dobbin for providing me with x-rays of the specimens. Mrs. Marguerette Schultz, S.I.O., brought to my 
attention the recent studies by K. Wyrtki, and my wife Cecelia, S.I.O., helped me locate bathythermograph data 
from the ships Yelcho, Anion Briinn and Esmeralda. For criticisms and comments on manuscript copy, or other 
courtesies, I thank W. A. Newman, S.I.O., Joseph R. Jehl, Jr., Raymond M. Gilmore, Reid Moran, and Dwight 
W. Taylor, San Diego Natural History Museum. 

LITERATURE CITED 

Allen, J. A. 

1899. Fur-seal hunting in the southern hemisphere, p. 307-319. In. Jordan, D. S.. et al.. The Fur seals and 
fur seal islands of the north Pacific Ocean. Part III. Special papers relating to the fur seal and to the 
natural history of the Pribilof Islands. Washington, Gov't. Print. Off. 
Bahomonde N., N. 

1966. Islas Desventuradas. Mus. Nac. Hist. Nat. Chile, ser. Educ. 6: 1-15. 
Barnes, H., and M. Barnes 

1958. Further observations on self-fertilization in Chthamalus sp. Ecology 39(3): 550. 
Crisp, D. J., and A. J. Southward 

1953. Isolation of intertidal animals by sea barriers. Nature 172(4370): 208-209. 
Douglas, G. 

1970. Draft check list of Pacific oceanic islands (foreward by E. M. Nicholson). Micronesia 5(2): 327-463. 



1971 ROSS: A NEW GENUS OF CHTHAMALIDAE 277 

Gilmore, R. M. 

1971. Observations on marine mammals and birds off the coast of southern Chile, early winter 1970. An- 
tarctic J. United States 6(1): 10-11. 
Johnson, A. W. 

1965-1967. The birds of Chile and adjacent regions of Argentina, Bolivia and Peru. Vol. 1, 1965: vol. 2, 
1967. Buenos Aires, Piatt Establicimientos Graficos S. A. 
Johnston, I. M. 

1935. The flora of San Felix Island. J. Arnold Arbor. 16(4): 440-447. 
Kellogg, R. 

1943. Past and present status of the marine mammals of South America and the West Indies. Ann. Rept. 
Smithsonian Inst. 1942: 299-316. 

McLean, J. H. 

1970. Descriptions of a new genus and eight new species of Eastern Pacific Fissurellidae, with notes on 
other species. Veliger, 12(3): 362-367. 

Meteorological Office 

1956. Monthly meteorological charts of the eastern Pacific Ocean. London, H.M.S.O., M.O. 518: 1-122 (not 
seen). 

Moore, L. B. 

1944. Some intertidal sessile barnacles of New Zealand. Trans. Roy. Soc. New Zealand 73(4): 3 15-334. 
Murphy, R. C. 

1936. Oceanic birds of South America. Amer. Mus. Nat. Hist. Vol. 1, 640 p. 
Newman, W. A. 

1961. On the nature of the basis in certain species of the Hembeli section of Chthamalus (Cirripedia, Thora- 
cica). Crustaceana 2(2): 142-150. 

1967. A new genus of ChthamaHdae (Cirripedia, Balanomorpha) from the Red Sea and Indian Ocean. J. 
Zool. London 153: 423-435. 

Newman, W. A., and A. Ross 

1971. Antarctic Cirripedia. Vol. 14. Antarctic Research Series, Amer. Geophys. Union. 257 p. 
Newman, W. A., V. A. Zullo and T. H. Withers 

1969. Cirripedia, p. 206-295. In, R. C. Moore (ed.), Treatise on Invertebrate Paleontology, Part R, Arthro- 
poda 4. 

Nilsson-Cantell, C. A. 

1957. Thoracic cirripeds from Chile. Reports of the Lund University Chile Expedition 1948-49. Lunds 
Univ. Arsskrift 53(9): 1-25. 

Pilsbry, H. A. 

1916. The sessile barnacles (Cirripedia) contained in the collections of the U.S. National Museum: in- 
cluding a monograph of the American species. U.S. Nat. Mus. Bull. 93: 1-366. 
Pope, E. C. 

1965. A review of Australian and some Indomalayan Chthamalidae (Crustacea: Cirripedia). Proc. Linnean 
Soc. New South Wales 90( 1): 10-77. 

Ross, A. 

1970. Studies on the Tetraclitidae (Cirripedia: Thoracica): a proposed new genus for the austral species 
Tetraclita purpurascens breviscutum. San Diego Soc. Nat. Hist., Trans. 16(1): 1-12. 

Serafy, D. K. 

1971. A new species of Clypeaster (Echinodermata, Echinoidea) from San Fehx Island, with a key to the 
Recent species of the Eastern Pacific Ocean. Pacific Sci. 25(2): 165-170. 

Skottsberg, C. 

1937. Die flora der Desventuradas-inseln (San Felix und San Ambrosio). Gotesborgs Kungl. Vetensk. Vit- 
terh. samhalles Handl., ser. B. 5(6): 1-88. 

1952. Weiter Beitrage Zur flora der Insel San Ambrosio . . . Arkiv fur Botanik, n.s., I (not seen). 
Utinomi, H. 

1968. A revision of the deep-sea barnacles Pachvlasma and Hexelasrna from Japan, with a proposal of new 
classification of the Chthamalidae (Cirripedia, Thoracica). Publ. Seto Mar. Biol. Lab. 16(1): 21-39. 

Withers, T. H. 

1928. Catalogue of fossil Cirripedia in the Department of Geology. Vol. 1. Triassic and Jurassic. Brit. Mus. 

(Nat. Hist.). 
1935. Catalogue of fossil Cirripedia in the Department of Geology. Vol. 2. Cretaceous. Brit Mus. (Nat. 
Hist.). 
Wyrtki, K. 

1966. Oceanography of the eastern Equatorial Pacific Ocean. Oceanogr. Mar. Biol. Ann. Rev. 4: 33-68. 



278 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

1968. Circulation and water masses in the eastern Equatorial Pacific Ocean. Intl. J. Oceanol. Limnol. 1(2): 
117-147. 
Zullo, V. A. 

1963. A classification and phylogeny of the Chthamalidae (Cirripedia: Thoracica). Proc. 16th Internatl. 
Congr. Zool., Washington, 1: 190. 



Department of Invertebrate Paleontology, Natural History Museum, P. O. Box 1390, 
San Diego, California 92112 




LIBRARY "* 

FEB 1 8 1972 

HARVARD 



THE LARVAL AND PUPAL STAGES OF FOUR SPECIES OF 
CAFIUS (COLEOPTERA: STAPHYLINIDAE) WITH NOTES 
ON THEIR BIOLOGY AND ECOLOGY 



GARY J. JAMES, IAN MOORE AND E.F. LEGNER 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 

VOL. 16, NO. 12 5 NOVEMBER 1971 



THE LARVAL AND PUPAL STAGES OF FOUR SPECIES OF 
CAFIUS (COLEOPTERA: STAPHYLINIDAE) WITH NOTES 
ON THEIR BIOLOGY AND ECOLOGY 

GARY J. JAMES, IAN MOORE, AND E. F. LEGNER 



ABSTRACT.— Staphylinid beetles of the genus Cafiiis live in and under piles of decaying seaweed on 
beaches in southern California. Seven species (seminitens. canescens. luteipennis. lithocharinus. decipiens, 
opacus. sulcicollis) occur together in this habitat. Their food consists largely of fly (Fucellia) larvae and 
pupae, although some were seen to prey upon amphipods and barnacles and scavenge on dead fish, others 
were predaceous on their own larvae as well as those of other species of Cafius. In mating, end-to-end pos- 
tures were observed, but more commonly males assumed a superior position. In the laboratory, eggs depos- 
ited in sand about one inch below the surface hatch in about 6 days, pupation occurring about 27 days later 
and adult eclosion on day 39. Early developmental stages are described and illustrated for luteipennis. lith- 
ocharinus. canescens and seminitens. 

A unique group of arthropods live on decaying seaweed on the beaches of southern 
Cahfornia. The habitat consists chiefly of surf grass, four species of brown algae, and ten 
species of red algae (Dawson, 1945, 1966). These plants are found together in clumps of 
all sizes, extending from the strand to the high tide level of the beach. From the moment 
that this vegetation appears on the shore, it is colonized by flies (Fucellia and Leptocera) 
and amphipods tolerant of repeated wetting and occasional submersion in sea water. 
Higher on the beach other accumulations of seaweed provide a habitat for additional 
species of flies as well as arachnids, mites, isopods and a variety of Coleoptera. 

Three species of Fucellia are probably most common in these habitats, while of the 
coleopterans, the Staphylinidae are usually the most abundant (Moore. 1956). This paper 
is concerned with Cafius. one of the more conspicuous genera of Staphylinidae. The four 
commonly found species are Cafius seminitens Horn, C. canescens Maklin, C luteipennis 
Horn, and C lithocharinus LeConte. Less common are C decipiens LeConte, C. opacus 
LeConte, and C sulcicollis LeConte. The slim elongated bodies of these specie enable them 
to move easily within the clumps of seaweed and to burrow into the upper layer of mixed 
sand and seaweed. 

METHODS 

Observations and samples of this community were taken weekly from June 1966 
through October 1967 on the beaches of San Clemente and Corona Del Mar in Orange 
County: and of La Jolla. Ocean Beach, Sunset Cliff's, and Coronado, all in San Diego 
County. All study sites were relatively undisturbed by beach cleaning machinery. Field 
and laboratory studies were conducted on feeding and mating behavior, the eff"ects of 
physical factors and competition (James, 1968). 

RESULTS AND DISCUSSION 

Habitat Observations.— V\! q noted that staphylinids always inhabited not only the sea- 
weed but also the wet and slimy upper layer of sand beneath. If disturbed, they moved to 
the tips of the drier seaweed, then flew to other nearby clumps. 

Laboratory experiments showed that all species were attracted to the smallest sand 
particles found in the beach habitat (James, 1968), and prefer a relative humidity of 95 
percent. We also found that all species could survive without food for about a week, but 
that further starvation was detrimental. Survival of individuals on the surface of seawater 



SAN DIEGO SOC. NAT. HIST., TRANS. 16 (12); 279-290. 5 NOVEMBER 1971 



280 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

in a plastic container ranged from 45 to 72 hours. 

We observed one individual o^ Cafius lithocharinus which had the longest survival in 
sea water, and found that it supported itself on its tibia on the water surface film for about 
2': hours. This individual, when placed in a plastic enclosed container partly filled with 
sea water, flew three times but finally resorted to merely floating on the surface as was 
characteristic of the other three species studied. When pushed beneath the water, all four 
species curled their abdomens up and back toward the thorax. The crook thus formed en- 
trapped a bubble of air. which was carried beneath the surface. Upon release the beetle 
floated back to the surface and extended its abdomen, then groomed the head and an- 
tennae with the forelegs. Flotation ceased when the beetle dropped its abdomen below 
the water surface, curved the abdominal tip back towards the head, and ceased leg move- 
ment. The body then sank to the bottom and movement stopped. 

Sea water thrown on beached seaweed caused beetles to come to the surface and fly 
away. A thorough soaking of the deposit drove out all beetles. Beetle flight was always 
away from the ocean, either up the beach or parallel to the surf, the ultimate goal being 
undisturbed piles of seaweed nearby. 

Fresh piles of seaweed were colonized by large numbers of adult staphylinids within 
two weeks of deposition. Once 800 individuals of Cafiiis lithocharinus were captured, 
marked with white paint, and released on the beach near their capture. None of the 
marked individuals was ever recovered. 

Predation.—Cafius canesceus and C. seminitens were voracious predators of both lar- 
vae and pupae of Fucellia. while C. lithocharinus and C. luteipennis were only casual feed- 
ers on larvae under experimental conditions (James. 1968). The adults of the four com- 
mon species are chiefly predatory, although some were seen to scavenge on dead grun- 
ion. Other known prey of Cafius includes amphipods and small barnacles; at times they 
also preyed on their own larvae and pupae as well as those of related species. 

Feeding Behavior.— Cafius seminitens and C. canescens upon encountering a fly larva 
would grasp it with the mandibles, and break the larval intergument. Oozing body fluids 
attracted other staphylinids. which joined in the consumption of the prey. We observed C. 
canescens breaking the surface layers of seaweed with its mandibles to feed on fly larvae 
within. This action attracted additional staphylinids which then shared the kill. On one 
occasion seven beetles consumed a fly larva in nine minutes. Cafius seminitens and C. ca- 
nescens were capable of excavating a hole in the puparium of a fly larva, and consuming 
the oozing fluids. Pupae were rarely shared. 

Mating Behavior.— Ahhough end-to-end mating postures were observed, usually the 
male assumed a superior position. The males use their mandibles to grip the females on 
the 2nd and 3rd abdominal segments below the elytra, in addition to using their legs to 
hold the female in position. In C. canescens the male extended the adaeagus while curling 
his abdomen around and downward to meet the female's upcurved abdomen. This posi- 
ti(m was retained for as long as 77 seconds. 

Immature Stages. — \n the laboratory, individually placed eggs of Cafius canescens 
were deposited about 1 inch below the sand surface. Gestation was about 6 days at room 
temperature. A newly hatched larva immediately excavated a burrow about 5 inches deep 
in a sand-filled test tube. Pieces of cockroaches which were dropped into the test tube 
were examined bv the staphylinid larva on the surface and finalK pulled into the sand 
burrow. 

The larva oriented itself with its head toward the sand surface. The burrow was en- 
larged and extensions were made in succeeding larval stages. Pupation occurred about 27 
days after egg laying at the 1/2 inch level in sand. Adult eclosion occurred on the 39th 



1971 



JAMES, MOORE AND LEGNER: CAFIUS 



281 



dav after the egg was laid. 

Larvae of C canescens were first collected from the beach at Coronado on 15 March 
1967. Overwintering apparently occurs in either the egg, pupal or adult stage. After 1 
April, C. canescens larvae were collected regularly in small numbers at all study sites. 
Cafius hiteipennis larvae were placed in a cage on 25 March and pupated 31 days later. 
At^ter 4 May, larvae of C. luteipennis were collected in small numbers from the Coronado 
site. On 8 Julv, larvae of C lithocharimis were first collected at Coronado. and the pupae 
were formed 34 days after a second set of larvae was collected on 27 August. 

The large larvae of Cafius seminiiens were first observed at Corona Del Mar on 18 
September. Pupation occurred 18 days later and adults emerged on the 28th day. Only 
Cafius seminitens larvae were seen to feed on seaweed fly larvae, devouring their prey in a 
similar manner as the adults. 

The various species of Cafius apparently breed at different times of the year, as in- 
dicated by their appearance at different dates. Cafius canescens and C luteipennis appear 
to breed in early spring, C lithocharinus in early summer, and C. seminitens in late sum- 
mer. 




Figure 1. Larva of Cafius canescens Maklin. a, 
anterior margin of clvpeus; b, urogomphus and 
pseudopodia; c. antenna; d, maxilla: e. dorsal 
view of body. 



^^^.^ 



V 



y- 



DESCRIPTIONS OF EARLY STAGES 

LARVAE 

The larva of the European Cafius sericeus Holme was described by Rey (1887) and 
that of C xantholoma (Gravenhorst) by Rupertsberger ( 1880). Paulian (1941) redescribed 
both of these species, using the name Remus sericeus for the former. Remus generally is 
considered a subgenus of Cafius. Paulian gave no generic description for the larva of 
Cafius. But a combination of characters from his key makes a good diagnosis of this 
genus. It follows: 

Cephalization accentuated: neck present; epicranial suture very long: gular sutures very 
long: ocelli four, arranged in a compact group near bases of antennae: nasal present: max- 



282 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

illarv palpus four-segmented; galea present, movable, with the aspect of a segment; lacina re- 
duced at maximum to some local spines in the apical region of the stipes; prosternum 
strongly chitinized. 

The combination of these diagnostic characters and the seashore habitat, permit easy 
recognition of Cafius larvae. 

In his key PauHan used other characters which new material shows to be too variable 
for a generic definition. Thus the middle teeth of the nasal do not differ from the lateral 
teeth in all the Pacific Coast species. And although the urogomphus is two-segmented and 
longer than the pseudopod in two of our species, in the other two it is shorter than the 
pseudopod. In one of the latter the urogomphus is distinctly one-segmented and spheri- 
cal. 

KEY TO THE KNOWN LARVAE OF CAFIUS 

1 A. Urogomphus longer than pseudopod. 
2A. Second segment of urogomphus widest at base, tapered to apex. 

3A. Composite macrosetae much more numerous than simple macrosetae. . . sericeus 
3B. Simple macrosetae much more numerous than composite 

macrosetae xantholoma 

2B. Second segment of urogomphus long, slender, cylindrical. 

4A. First segment of maxillary palpus one-half as long as second 

segment luteipennis 

4B. First segment of maxillary palpus about as long as second 

segment lithocharinus 

1 B. Urogomphus shorter than pseudopod. 

5A. Urogomphus two-segmented, the segments subcylindrical canescens 

5A. Urogomphus one-segmented, spherical seminitens 

LARVA OF CAFIUS LUTEIPENNIS HORN 

Co /or.— Pale, with head dark testaceus. 

Head subquadrate. widest near basal angles, slightly narrowed to apical angles. 
Neck about three-fourths as wide as head. Ocelli four, in a small cluster near apical an- 
gles. Clypeal margin with nine teeth, the two outer teeth on each side smallest, the next 
two on each side longer than wide, the central tooth little more than half as long as 
those next to it (Fig. 3A). Antennae four-segmented, the first segment short, the second 
and third about as wide as first and each about twice as long as wide, the third with a 
small ovoid seta at apex, the fourth about half as wide and half as long as third with a 
very small, round modified seta at apex (Fig. 3C). Maxilla (Fig. 3D) with the stipes al- 
most as long as palpus; galea small elongate-ovoid; maxillary palpus four-segmented, 
the first segment about as long as wide, the second as wide as and twice as long as first, 
the third somewhat narrower and shorter than second, the fourth small, elongate-ovoid. 
Ligula about as long as first segment of labial palpus, pubescent basally. Labial palpus 
three-segmented, the first segment about twice as long as wide, the second a little nar- 
rower and shorter than first, the third much narrower and shorter than second. Gular 
sutures united in basal three-fifths, thence divergent to apex. 

Thorax.— Pronolum a little wider than long, widest near basal angles, narrowed 
slightly to apical angles, with a few scattered setae at sides and on disc. Mesonotum and 
metanotum shorter and a little wider than pronotum. with sparse scattered setae. 

Abdomen with parallel sides in basal half, thence slightly narrowed to apex, the 



1971 



JAMES. MOORE AND LEGNER: CAFIUS 



283 



segments of about equal length throughout, sparsely setose. Pseudopod about twice as 
long as wide. Urogomphus two-segmented, longer than pseudopod, the segments very 
slender, the second segment much narrower and somewhat shorter than first. 

Length.— 1 mm. 

Material examined.— Hold Del Coronado Beach, Coronado, San Diego Co., Cali- 
fornia, April 1967, Gary James coll. 

Notes.— This species can be distinguished by the combination of the very long slen- 
der two-segmented urogomphus and the very short first segment of the maxillary pal- 
pus. 



pi 



.^i^/AfJ/1-, 




kT^"^ 







Figure 2. Larva of Cafius seminitens Horn, a, 
anterior margin of clypheus: b, urogomphus and 
pseudopodia: c, antenna; d, maxilla; e, dorsal 
view of body. 



LARVA OF CAFIUS LITHOCHARINUS LE CONTE 

Co/or.— Head and thorax dark ferruginous, abdomen pale ferruginous. 

Head subquadrate, widest near basal angles, slightly narrowed from base to apex. 
Neck about four-fifths as wide as head. Ocelli small, dark, in a small cluster near apical 
angles. Frontal suture joining epicranial suture at an obtuse angle near anterior third of 
head. Clypeal margin with nine teeth, the central tooth and two outer teeth smallest (Fig. 
4A). Antenna with first segment short, the second and third each about twice as long as 
wide, the third with an ovoid modified seta at apex, the fourth much narrower and shorter 
than third, with a small ovoid modified seta at apex (Fig. 4C). Maxilla (Fig. 4D) with stipes 
as long as palpus; galea very small, ovoid; maxillary palpus four-segmented, the first seg- 
ment about twice as long as wide, the second a little narrower and shorter than the first, the 
third much narrower and somewhat shorter than second, the fourth small, ovoid. Ligula 
shorter than first segment of labial palpus, pubescent. Labial palpus three-segmented, the 
first segment almost twice as long as wide, the second narrower and shorter than first, the 
third small, ovoid. Gular sutures united in basal two-thirds, divergent anteriorly. 

Thorax .-Pronotum about as wide as long, widest near basal angles, narrower ante- 



284 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



riorly. Mesonotum and metanotum much shorter and slightly wider than pronotum. 

Abdomen gently tapered from base to apex, the first segment short, the others progres- 
sively slightly longer, with scattered sparse setae throughout. Pseudopod nearly three times 
as long as wide. Urogomphus longer than pseudopod, two-segmented, the first segment al- 
most as long as pseudopod, the second long and very slender (Fig. 4B). 

Length.— S-l 1 mm. 

Material examined.— Ten specimens: Hotel Del Coronado Beach, Coronado, San 
Diego Co., California, August 7, 1967, Gary James coll. 

Notes.— This larva most closely resembles that of C luteipennis, from which it may be 
distinguished by the relatively longer first segment of the maxillary palpus and by shorter 
clypeal teeth. 





Figure 3. Larva of Cafiiis luleipennis Horn. a. 
anterior margin of clypeus; b, urogomphus and 
pseudopodia; c, antenna; d. maxilla: e. dorsal 
view of body. 



Figure 4. Larva of Cafius lithocharinus Le- 
Conte. a, anterior margin of clvpeus: b. uro- 
gomphus and pseudopodia: c. antenna: d, 
maxilla: e, dorsal view of body. 



LARVA OF CAFIUS CANESCENS MAKLIN 

Co/or.— Pale testaceous, with head ferruginous. Ocelli and base and apex of mandibles 
dark. 

//ertJsubquadrate, widest just before the rounded basal angles, gradually narrowed to 
near the ocelli. Neck about five-sevenths as wide as head. Ocelli tour, in a close cluster near 
the anterior angles. Frontal suture joining epicranial suture at an obtuse angle at about the 
anterior third of the head. Clypeal margin with nine similar teeth, the penultimate outer 
tooth on each side somewhat shorter than the others (Fig. 1 A). Antenna with first segment 
widest, about as long as wide, the second segment about twice as long as first, the third 



1971 



JAMES, MOORE AND LEGNER: CAFIUS 



285 



about as long as second and with a small modified segment at apex, fourth segment much 
narrower and shorter than third (Fig. IC). Maxilla (Fig. ID) with stipes almost as long as 
palpus, about twice as long as wide. Galea small, ovoid: maxillary palpus with first two seg- 
ments subequal, the third much shorter and narrower than second, the fourth minute. Li- 
gula about as long as first segment of labial palpus, pubescent in basal half Labial palpus 
three-segmented, the first segment about twice as long as wide, the second a little shorter 
and distinctly narrower than first, the third narrower than second, very little longer than 
wide. Gular sutures united in basal three-fifths, thence divergent to apex. 

Thorax —VronoXuva subquadrate. a little wider than long, widest near middle, thence 
narrowed slightly to base and to apex. Mesonotum and metanotum much shorter than and 
about as wide as pronotum. Each segment with a row of setae at anterior, lateral and pos- 
terior margins and a very few scattered setae on disc. 

Abdomen widest at base, slightly tapered to apex; first segment shortest, the segments 
increasing in length progressively to apex; a little more densely setose than thorax. Pseudo- 
pod about twice as long as wide. Urogomphus two-segmented, shorter than pseudopod, 
subcylindrical(Fig. IB). 

Length.— 9 mm. 

Material examined— ¥'\\Q specimens, Vi mile west of pier, San Clemente, Orange Co., 
California, 12 April 1967, Gary James coll. 

Notes— T\\\?, larva differs from the other larvae of Cafius in having a two-segmented 
urogomphus that is much shorter than the pseudopod. 



Figure 5. Pupa of Cafius canescens Maklin. a, 
ventral view; b, lateral view. 





LARVA OF CAFIUS SEMINITENS HORN 

Co/or.— Pale testaceous, with head and pronotum ferruginous, the base and apex of 
mandibles darker. Head subquadrate, a little wider than long, widest near basal third. 



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thence slightly narrowed to apex. Neck about three-fourths as wide as head. Ocelli very 
pale, difficult to detect. Frontal sutures joining epicranial suture at an obtuse angle at about 
the apical third of head. Clypeal margin with nine teeth, the central tooth distinctly smaller 
than the others (Fig. 2A). Antenna four-segmented, the first segment short, the second and 
third as wide as and more than twice as long as first, the third with a rounded modified seta 
at apex, the fourth small ovoid (Fig. 2C). Maxilla with stipes as long as palpus, about twice 
as long as wide; galea small, oval; maxillary palpus (Fig. 2D) with a separate sclerotization 
forming a very short ring at base in the form of an extra segment which may represent the 
lacina; first segment of palpus about twice as long as wide, the second nearly as wide and as 
long as first, the third a little narrower and shorter than second, the fourth small, ovoid. 
Ligula about as long as first segment of labial palpus, pubescent at base. Labial palpus 
three-segmented, the first segment about twice as long as wide, the second narrower and a 
little shorter than first, the third much narrower and shorter than second. Gular sutures 
united in basal three-fifths, thence divergent to apex. 

Thorax .—Pvonolum transverse, the sides well rounded, widest at basal third, with a few 
scattered setae on disc and at sides. Mesonotum and metanotum narrower and shorter than 
pronotum, with a row of setae at base, sides and apex. 

Abdomen slightly tapered from base to apex, the first few segments short, the apical 
segments progressively narrower and longer. First four segments irregularly, and densely 
set with short stout peg-like setae, the next five segments progressively more sparsely setose. 
Pseudopod about twice as long as wide. Urogomphus one-segmented, spherical, much 
shorter than pseudopod (Fig. 2B). 

Lenglh.— \0-\4mm. 

Material examined.— Five specimens. Corona Del Mar, Orange Co., California, 16 
September 1967, Gary James collector. 

Note.— This larva differs in several respects from other known larvae ofCaJius, but par- 





Figure 6. Pupa of Cafius seminilens Horn, a, 
ventral view; b, lateral view. 



1971 



JAMES. MOORE AND LEGNER: CAFIUS 



287 



ticularly in the spherical one-segmented urogomphus, the "extra segment" at the base of 
the maxillary palpus, the very transverse pronotum and the densely setose first four abdom- 
inal segments. 

On the basis of larval characters this species might be placed in a separate genus or 
even separate subfamily, but adult characters preclude such a course. Because of the great 
similarity of their imagoes, this species and C canescens are usually placed by themselves 
in the subgenus Bryonomus. 

PUPAE 

The pupa of the European species C sericeus Holme, was described and illustrated by 
Paulian (1941). In his key to the genera of the pupae of the Staphilinoidea he diagnosed 
sericeus as follows: 

Pronotum with strong marginal setae, without discal setae: dorsum of abdomen fiat, epi- 
pleurae prominent: with two long slender cerci which have whorls of fine setae apicallv. 

The pupae of the Pacific Coast species show that some of these characters are specific 
rather than generic. 

Hinton ( 1958. 1963a. 1963b) called attention to the fact that among the few pupae of 
Coleoptera studied the most apparent useful taxonomic characters are the number and ar- 
rangement of tubercles, macrosetae and pubescence. The pupae of Cafius which have been 
studied share the following characters: 

Body without fine pubescence except dense fine pubescence at extreme tip of urogomphus. 
Tubercles arranged in a single row at anterior margin of pronotum, two to four rows on middle 
and posterior tibiae and one tubercle each at lateral men-gin of abdominal segments five and 
six. Macrosetae restricted to pronotal and abdominal tubercles. 



Figure 7. Pupa of Ccifius luieipennis Horn. a. 
ventral view: b. lateral view. 




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SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure 8. Pupa of Cafius lithocharinus Le- 
Conte. a, ventral view; b, lateral view. 



KEY TO THE KNOWN PUPAE OF THE AMERICAN SPECIES OF CAFIUS 

1 A. Anterior margin of pronotum with a single row of 

nine setigerous tubercles each side seminitens 

1 B. Anterior margin of pronotum with a single row of 

fewer than nine setigerous tubercles each side. 
2A. Anterior margin of pronotum with a single row of 

three setigerous tubercles each side canescens, lithocharinus 

2B. Anterior margin of pronotum with a single row of 

four setigerous tubercles each side hiteipennis 

Characters have not been found for the separation of the pupae of C canescens and 
lithocharinus. 



ACKNOWLEDGMENTS 

We are indebted to Dr. Lauren B. Anderson. Mrs. Patricia Farreli and Mrs. Arlene Sansevero of the Univer- 
sity of California at Riverside and to Fred G. Andrews of the California Department of Agriculture at Sacramento 
for aid in locating literature. 

LITERATURE CITED 

Dawson. E. Y. 

1945. An annotated list of the marine algae and marine grasses of San Diego County, California. Occas. 
Papers San Diego Soc. Nat. Hist. 7: 1-87. 
Dawson, E. Y. 

1966. Marine botany. An introduction. Holt Rinehart and Winston, Inc., N.Y. 371 p. 
James, G. J. 

1968. The biology and ecology of four species of the genus Cafius (Coleoptera: Staphylinidae). M.S. 
Thesis, San Diego State College. 72 p. 



1971 JAMES, MOORE AND LEGNER: CAFIUS 289 

Moore, I. 

1956. Notes on intertidal Coleoptera with descriptions of the early stages (Carabidae, Staphylinidae, Mala- 
chiidae). Trans. San Diego Soc. Nat. Hist. 12: 207-230. 
Paulian. R. 

1941. Les Premier etats des Staphvlinoidea. Etude dc morphoioaie comparee. Mem. Mus. Hist. Nat. Paris, 
n. ser.. 15: 1-361. 
Rey, C. 

1887. Essai d'etudes ser les larves des coleopteres. Ann. Soc. Linn. Lyon 33: 146-1480. 
Rozen, J. G.. Jr. 

1958. Systematic study of the pupae of the Oedemeridae (Coleoptera). Ann. Ent. Soc. Amer. 52: 299-303. 
1963a. Preliminary systematic study of the pupae of the Nitidulidae (Coleoptera). Amer. Mus. Novitates 

2124:1-13. 
1963b. Two pupae of the primitive suborder Archostemata (Coleoptera). Proc. Ent. Soc. Washington 65: 
307-310. 
Rupertsberger. M. 

1880. Biologic der Kafer Europas. Eine Ubersicht der biologischen Literatur. Donau. Linz. 295 p. 



Orange Coast College. Costa Mesa, California 92626 (G.J.J. ), and Division of Biological 
Control, Department of Entomology, University of California. Riverside, California 9 '")()'' 
(LM.andE.F.L.) 




MUij. CUM p. ^oc; 

LIBRARY 

FEB 1 8 1972 

HARVARD 
UNIVERSJTY 



THE COLOR PATTERNS OF DOWNY YOUNG 
RATITES AND TINAMOUS 



JOSEPH R. JEHU JR. 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 

VOL. 16, NO. 13 15 NOVEMBER 1971 



THE COLOR PATTERNS OF DOWNY YOUNG 
RATITES AND TINAMOUS 

JOSEPH R. JEHL, JR. 



ABSTRACT.— Plumage patterns of downy young ratites indicate that the Casuariidae and Dromiceiidae are 
closely related, and they suggest that the Struthioniformes and Casuariiformes may be more closely related to 
each other than either is to any other hving ratite taxon. Relationships of the Rheiformes and Apterygiformes 
are not clarifed. The Tinamidae fall into two distinct groups of genera: 1) Tinamus, Nothocercus, and Cryplu- 
rellus. and 2) Rhynochotus. Nothura, Nothoprocta, and Tinamotis; chicks of Taoniscus were not examined. 
Chick plumages provide no evidence for close relationship between tinamous and any ratite taxon. 

The ratites are large, flightless, running birds with an unkeeled sternum which, with 
one minor' exception, are now restricted to the southern hemisphere. They include the ex- 
tant families Struthionidae, Rheidae, Casuariidae, Dromiceiidae, and Apterygidae, and the 
extinct Opisthodactylidae, Dromornithidae, Emeidae, Eleutherornithidae, and Aepyorni- 
thidae (Brodkorb, 1963). Interrelationships among these famihes have long been among 
the most controversial problems in avian systematics (Bock, 1963), as has the question of 
whether these flightless birds share a common ancestor. (References to much of the relevant 
literature are contained in Bock, 1963, de Beer, 1956, 1964, and Parkes and Clark, 1966). 
Some recent authors (e.g.. Bock, 1963; Parkes and Clark, 1966) have argued that the ratites 
are probably monophyletic, but ornithologists have yet to reach a consensus on this point. 

The tinamous (Tinamidae) are ground-dwelling, chicken-like birds of the Neotropics. 
Their possible close relationship to the ratites, and particularly to the rheas, has received 
much attention, but relationships within the Tinamidae have been largely ignored. 

Because chick color patterns have been used to elucidate relationships within certain 
other taxa (e.g., Podicipedidae: Storer, 1967; Anatidae: Delacourand Mayr, 1945; Tetrao- 
ninae: Short, 1967; Charadrii: Jehl, 1968) their importance in suggesting relationships wi- 
thin the ratites and tinamous was investigated. The results provide limited evidence in 
support of relationships that have been suggested among ratites, and they clarify the subdi- 
visions of the tinamous. 

In this study I was able to examine specimens or descriptions of most ratite species, as 
well as living chicks of Struthio camelus, Dromiceius novaehoUandiae and Crypturellus soui 
in the San Diego Zoo. Most tinamou genera were also available, but many species were not. 
Studies in other groups have shown that an index to color pattern within a genus can usu- 
ally be obtained from a few representative species. Thus, the general conclusions reached 
here are unlikely to be aff'ected by the limited material. Nevertheless, further collecting is 
desirable, particularly of species in the genera Nothoprocta, Crypturellus, and Taoniscus. 

In the following section the major color patterns are described for each taxon. For each 
species the number of specimens examined is given in parentheses. Species for which I have 
examined only a description in the literature are denoted by an asterisk. In view of the lim- 
ited material, no attempt has been made to provide descriptions adequate for species iden- 
tification. 

RATITES 

STRUTHIONIFORMES: STRUTHIONIDAE 
Struthio: camelus (2) 

Ostrich chicks (Fig. lA) are covered on the back with a thick mat of tan and blackish 
down feathers. Several barbs on each of these feathers are prolonged, flattened, and 

SAN DIEGO SOC. NAT. HIST., TRANS. 16 ( 13): 291-302, 15 NOVEMBER 1971 



292 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 








\ 




3 



Hf.* 





Figure 1. Downy young ratites in dorsal and ventral view: (A): Siruthio camelus (B) Pterocnemia pennata, (C) 
Dromiceius novaehoUandiae, (D) Casuarius bennetti. 



1971 



JEHL: RATITES AND TINAMOUS 



293 



twisted, and intertwine with those from adjacent feathers. The resuhing appearance is that 
of a pile of straw and I cannot determine whether any underlying color pattern is present. 

There is a definite though variable striped pattern on the neck. Because several of the 
stripes are discontinuous, the configuration of this pattern is not as evident in flattened study 
skins as it is in living chicks (see photos by Sauer and Sauer, 1966: Fig. 31, 32). It consists 
(Fig. 2) of a mid-dorsal stripe (A) and one dorso-lateral (B) stripe on each side of the neck; 
an interrupted stripe (C) on each side of the neck; an interrupted stripe (D) on the ventro- 
lateral surface of the neck that starts near the base of the bill and continues to the upper 
chest, and (E) a short interrupted stripe in the throat region. On the head a stripe extends 
from the base of the upper mandible, dorsal to the eye, to the ear region; facial markings are 
variable but usually include a dark spot posterior to the eye and a short hne from the rictus 
that passes dorsally anterior to the ear. 




Figure 2. The interrupted pattern of head and neck striping in Struthio camelus. The major stripes are indicated. 



RHEIFORMES: RHEIDAE 

Rhea: americana (6). Pterocnemia: pennata (4) 

Color patterns of Pterocnemia (Fi^s. IB, 3C) and Rhea chicks are identical. A dark cen- 
tral stripe extends from the crown to the rump, but broadens to a diamond-shaped figure on 
the mid-back and sends branches along the dorsal surface of the wing. Lateral stripes ex- 
tend from the rump to the mid-back, where they turn ventrally. When the chick's wings are 
folded, the wing and lateral stripes appear to form a continuous stripe along the entire 
length of the body. The chin and belly are whitish; the neck is dusky gray and this color- 
ation extends onto the chest as a thin central line. 

The ground color of Pterocnemia chicks is whitish and the patterned areas are choco- 
late brown; minor pattern variations occur in the width of the striping. In Rhea the ground 
color is tan, the patterning dark brown. Rhea chicks hatched in captivity show considerably 
more color variation than wild chicks. This presumably results from inbreeding and selec- 
tion for albinistic birds. 

CASUARIIFORMES: CASUARIIDAE, DROMICEIIDAE 

Casuarius: casuarius (3), unappendiculatus, bennetti (2) 

Species limits in the cassowaries are not well known. Peters (1931) lists six species, 



294 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



but Rand and Gilliard (1967) recognize only three. 

Cassowary chicks are pale brown with well-marked longitudinal stripes on the back. 
The head is chestnut or tan, and may be unmarked or dotted irregularly with dark brown 
markings (Figs. ID, 3B). On the back three major dark brown stripes extend from the 
shoulder region to the rump; within each of these stripes a light central stripe of varying 
prominence is formed by the chestnut tips of the feathers. A dark stripe on the side is par- 
alleled ventrally by an indistinct stripe that appears to be continuous with the leg stripe. 
The belly and chin range from light tan to light brown and are unmarked. The neck and 
chest are irregularly flecked with gray-brown markings; in most specimens the neck color- 
ation continues on to the chest as a thin central line, similar to that found in the Rheidae 
(cf. Figs. IB, D). 






Figure 3. Diagrammatic color patterns of; (A) Dromiceius novaehoUandiae, (B) Casuarius casuarius, and (C) 
Pterocenmia pennata. 



Dromiceius: novaehoUandiae (5) 

Emu chicks are boldly patterned (Figs. IC, 3 A, 4). The head markings show no con- 
sistent arrangement but the neck and back markings are distinctive. Dorsally, a central 
(A) and two lateral (B) stripes extend from the occiput to the rump; a stripe from the au- 
ricular region broadens at the shoulder, where it acquires a buff"y central stripe, and con- 
tinues to the flank; a buff'-centered stripe on the lateral surface of the thigh is bordered by 
a thin (sometimes interrupted) black stripe on the antero-lateral surface. On the ventral 
surface of the neck stripes run from the base of the bill to the sides of the chest (D); a 
short central stripe (E) is present in the throat region. Pattern details are variable. In some 
birds parts of stripes are interrupted or missing, and in the bird shown in Figure 4 the 
posterior part of the central stripe has fused with a lateral stripe. 



1971 



JEHL: RATITES ANDTINAMOUS 



295 





Figure 4. Head and neck pattern of Dromiceius novaehollandiae. The major stripes are indicated. 



APTERYGIFORMES: APTERYGIDAE 

Apteryx: australis*, oweni, haasti 

Newly-hatched Kiwis seem to be unpatterned. No trace of a color pattern could be 
detected in a well-developed embryo o^ Apteryx australis preserved in alcohol at the Car- 
negie Museum (Mary H. Clench, pers. comm.). Oliver (1957: 48) described the nestling of 
Apteryx australis as follows: "Upper surface black streaked with brown mainly on the 
shafts and bases of the feathers. On the head, breast and abdomen it is greyer." 



TINAMOUS 



TINAMIFORMES: TINAMIDAE 



Tinamus: tao, soUtarius*, osgoodi, major (5), guttatus 

De Schauensee's (1966) classification of tinanmous is followed in this paper. 

The head pattern in T. major is complex (Figs. 5, 6); a grayish patch extends from the 
base of the bill onto the forehead; posteriorly, a brown crown patch extends over the occi- 
put and onto the neck; a gray-brown postorbital stripe runs from above and behind the 
eye to the side of the neck; a brownish line of variable prominence extends from the base 
of the bill to the anterior corner of the eye and continues posteriorly as a broad band 
through the auriculars; the cheeks and throat are grayish, except for a short, dark malar 
stripe. Feathers on the nape of the upper back are brown, lightly barred with gray, 
whereas those on the midback appear uniformly brown. A broad, light brown or golden 
band on the lower back extends to the rump and is bordered laterally by a thin line of 
dark feathers (Fig. 5). The color pattern of T. solitarius is similar (Salvadori, 1895: 502). 

Nothocercus: bonapartei (I), Julius (1), nigricapillus 

The coloration of the two species o^ Nothocercus at hand differs slightly, but there are 
no important differences in color pattern. In A'^. bonapartei (Figs. 5, 6) a light grayish patch 
from the base of the bill extends onto the forehead, where it blends with a dark gray crown 
that extends onto the occiput; the face and cheeks, including a broad supraorbital stripe, 
are grayish, and an obscure dark line runs from the base of the bill to the anterior corner 



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SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



of the eye; the throat is grayish-white. The back is uniformly brown, individual feathers 
being thinly barred with black. In N. Julius the crown patch is grayish-white and is sharply 
bordered laterally by a dark stripe; the facial area is orangish. 






Figure 5. Downy young tinamous. Left to right: Tinamus major, Crypturellus boucardi, Crypturellus undulatus, 
Crypturellus soui, Nothocercus bonapartei. 

Crypturellus: cinereus, soui {!), ptaritepui, obsoletus, undulatus (1), brevirostris, bartletti, 
variegatus (2), atrocapillus, noctivagus, duidae, cinnamomeus (1), transfasciatus, strigulosus, 
casiaquiare, boucardi (2), saltuarius, kerriae, parvirostris, tataupa (2) 

Color patterns in this large genus are variable (Figs. 5. 6). In C boucardi, variegatus, 
cinnamomeus, tataupa and undulatus, the head pattern is similar to that of Tinamus except 
that a light brown narrow median stripe is enclosed in the posterior part of the crown 




Figure 6. Head patterns of tinamou chicks. Left to right: Tinamus major (2). Crypturellus undulatus, Cryptu- 
rellus soui, Nothocercus bonapartei. 



1971 



JEHL: RATITES AND TINAMOUS 



297 



patch, and the auricular stripe is narrower and much less prominent (Fig. 6); in variegatus 
(see Beebe. 1925; Fig. 22) the borders between the prominent head patches are less dis- 
tinct; in sold the auricular patch is absent and the head patches blend into each other, as 
in Nothocercus. The back patterns of boncardi, variegatus and cinnamomeus are similar to 
that of Tinamus but lack a pale patch on the lower back; in undiilatiis and tataupa the 
back is uniformly brown and lightly barred; in soid the feathers appear uniformly brown- 
ish but are finely barred with black, as in Nothocercus. 




Figure 7. Downy young tinamous. Left to right: Rhvnchotus rufescens, Nothura maculosa. Nothoprocta curvi- 
rostris, Nothoprocta pentlandii, Nothoprocta perdicaria. Eudromia elegans. 

Rhvnchotus: rufescens (2) 

The color pattern o^ Rhvnchotus chicks (Figs. 7, 8) is unlike that of the preceding gen- 
era. The back appears to be longitudinally streaked with dark and light feathers in no ob- 




.,A^ • 1 1 iiV. 







Figure 8. Head patterns of tinamou chicks. Lett to right: Rhvnchotus rufescens. Nothura maculosa. Nothoprocta 
curvirostris, Nothoprocta perdicaria, Eudromia elegans. 



298 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

vious pattern and to be overlain by a thin coat of stiff bristles. This streaked pattern 
reflects the structure of the dorsal down feather, which consists of a rachidial main feather 
and a prominent aftershaft of almost equal size. The rachis of the main feather bears 
dark-colored barbs for about two-thirds of its length, then forks to form a pair of stiff 
bristles; the aftershaft bears light colored barbs for almost its entire length. A similar 
down structure is present in Nothura, Nothoprocta, and Eiidromia. In down feathers ofTin- 
amiis. Nothocercus and Crypturelliis, a rachis is poorly developed and aftershafts seem to 
be lacking or rudimentary. 

The head pattern is well defined. A narrow blackish crown patch which extends from 
above the eye to the occiput is bordered by a thin buffy stripe that begins at the base of 
the bill but forks on the forehead to encircle the crown patch; the buffy stripes, in turn, 
are bordered by a dark stripe that extends from the base of the bill to the nape. The face 
is generally buffy, but with interrupted dark stripes in the post-orbital and auricular re- 
gions; there is a thin malar stripe (Fig. 8). 

Nothoprocta: taczanowskii, kalinowski, ornata (1); perdicaria (1), cinerascens, pentlandii 
(2), curvirostris (3) 

Chicks of Nothoprocta (Figs. 7, 8), Hke those of Rhynchotus have a streaked pattern. 
In Nothoprocta, however, the bristle-like tips of the main feather are much less prominent 
and usually are flanked by one or more additional barbs. The chick of TV. perdicaria, in 
addition to being streaked dorsally, has a sHghtly barred appearance, because the dark 
feathers are buffy at both the base and tip. 

The head markings in perdicaria and ornata are similar to those of Rhynchotus, ex- 
cept that the boundaries between the major stripes are less pronounced. In curvirostris 
dind pentlandii the head is dotted irregularly with black, brown, and white, but the pattern 
is a variation of that found in perdicaria. 

Nothura: boraquira, minor, darwinii, maculosa (1), chacoensis 

The chick of Nothura maculosa (Figs. 7, 8) also has a streaked pattern and is ex- 
tremely similar to that oi Rhynchotus; the hairlike bristles of the dark back feathers, how- 
ever, are less strongly developed than in that genus. The head pattern is hke that of 
Rhynchotus, except that the borders between the major stripes are less clearly defined. 
Nothura lacks a post-orbital stripe; auricular and malar stripes, though present, are incon- 
spicuous. 

Taoniscus: nanus 

I have seen neither a chick nor a description of the downy plumage of this species. 

Eudromia: elegans (5),formosa 

The dorsal color pattern of Eudromia (Fig. 7) is similar to that of the other streaked 
genera, although light-colored feathers are less abundant than in Rhynchotus, Noth- 
oprocta and Nothura. The darker feathers are subterminally barred with blackish brown, 
so that the chick, like that of Nothoprocta perdicaria, appears slightly barred. The bare 
tips of these feathers are much shorter than in the genera hsted above. 

The dorsal surface of the head and neck is flecked with gray and brown; from each 
side of the biU an indistinct whitish line extends across the crown to the occiput; the face 
and throat are generally buffy-white, but the lores are dark; posterior to the eye a brown 
stripe extends through the auriculars to the side of the neck; there is prominent malar 
stripe (Fig. 8). 

Tinamotis: pentlandii (3), ingoufi 

So little down remains on the three half-grown chicks of T. pentlandii that I have ex- 



1971 JEHL: RATITES AND TINAMOUS 299 

amined that no assessment of the body pattern is possible. The head, however, is boldly 
striped. Two broad dark stripes, one on each side of the bill, pass dorsal to the eyes and 
around the periphery of the crown to the nape; a small white-centered patch on the occi- 
put extends onto the nape as a thin median line; a stripe from the lores passes through the 
eye to the auricular region; and a malar stripe extends from the gape through the cheeks 
and onto the side of the neck. At first glance the head markings of Tinamotis seem unique 
but the pattern is clearly a variant of those found in genera with streaked chick plumages 
and closely resembles that of Nothoprocta perdicaria. 

DISCUSSION 

RATITES.-In the following discussion I assume that similarities in complex patterns and 
the potential for easy transformation of one pattern to another are evidence for close rela- 
tionship. The sequence of pattern transformation cannot be determined in the absence of 
information regarding the ancestral downy pattern. However, if one assumes that the ra- 
tites are monophyletic, it is reasonable to infer that a striped pattern of some sort may 
have been primitive, inasmuch as a striped pattern or presumed remnant thereof is pres- 
ent in four of the five extant ratite families and is lacking only in the Kiwis, whose bur- 
row-nesting habits are unusual in that group. 

The downy young plumages provide limited evidence regarding relationships among 
ratite families. The long-accepted close affinity of cassowaries and emus is confirmed by 
the similar color patterns of their chicks. The transformation of a cassowary pattern to 
that of an emu requires only a change in head pattern (variable in cassowaries) and the 
introduction of a light central stripe to each of the major dorsal stripes. A hint of that 
line— the light chestnut tips to the central feathers of each stripe— is present in the casso- 
waries. 

Ostrich chicks lack any discernible dorsal pattern, but the pattern of head and neck 
striping is closely similar to that of an emu (cf Figs. 2, 4). This suggests, as Sibley (1960) 
and Glenny (1965) have indicated, that the Struthioniformes and Casuariiformes may be 
more closely related to each other than either is to any other hving ratite order. If so, the 
neck pattern in ostriches might represent the remnant of a striped pattern that extended 
over much of the body. One could speculate that this pattern was replaced by a uniform 
pattern, and was complemented by a straw-like down structure, insuring crypticity in 
areas of sparse vegetation as proto-ostriches became adapted to desert habitats. 

Downy plumage patterns do not suggest an alliance between rheas and other ratites. 
Although it would be possible to derive the striped rhea pattern from that of a cassowary, 
for example, no easy transformation is evident. Similar chest patterns in rheas and casso- 
waries are simple and could result from convergence. Thus, they provide no evidence for 
relationship. 

Kiwis are thought to be most closely related to the extinct moas and to the living cas- 
sowaries and emus (Parkes and Clark, 1966). Young kiwis are unpatterned and their plu- 
mage offers no evidence on their possible relationship to other ratites. The lack of a 
distinct pattern may be a derived condition associated with the burrow-nesting habits of 
these birds. 

TINAMOUS.-Downy young tinamous fall into two distinct groups of genera: 1) Tinamus, 
Nothocercus, and Crypturellus; 2) Rhynchotus, Nothura, Nothoprocta, Eudromia, and 
Tinamotis. Chicks of Taoniscus (not available) presumably fall into the second group. 
These groups correspond to the subfamilies Tinaminae and Nothurinae, respectively, of 
Miranda-Ribiero (1938). The downy young provide no evidence for von Boetticher's 



300 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

(1934) subdivision of the Nothurinae into two subfamilies, Rhynochotinae {Rhynochotus, 
Nolhura, Nothoprocta, Taoniscus) and Eudromiinae {Eudromia, Tinamotis). 

Because the Tinaminae are forest dwellers whereas the Nothurinae are birds of the 
grasslands, pattern similarities within these groups might be attributable to convergence. 
This seems unlikely because patterns in the Tinaminae are complex, and the Tinamus 
pattern can be easily transformed into the more uniform pattern of Nothocercus through a 
small series of steps such as are represented in existing species oT Crypturellus (Figs. 5, 6). 
Chicks of the Nothurinae are united by similarities in back pattern and feature structure; 
differences between color patterns of Rhynchotus and Eudromia are largely bridged by in- 
termediate patterns within Nothoprocta (Figs. 7, 8). 

Interrelationships of tinamou genera diagrammed by von Boetticher (1934; also re- 
produced in Ward, 1957: 336) are largely supported by Ward's study of mallophagan par- 
asites on tinamous. Ward's suggestion that Nothocercus is more closely related to 
Crypturellus than to Tinamus, however, is also indicated by the similarity of chick color 
patterns. In addition, chick plumages suggest that Nothoprocta may be somewhat more 
closely allied to Eudromia (and Taoniscus) than von Boetticher postulated. In the species 
that I have examined there are no close similarities between patterns in the Tinaminae 
and Nothurinae. 

The attempt to establish a phylogenetic hnk between the ratites and tinamous, and 
particularly between the rheas and tinamous, dates at least to the early 19th century, and 
the downy young have been used to give some support to that view. Salvadori (1895: 494) 
stated that newly hatched tinamous "... are covered with down, and more or less closely 
resemble the young of some of the Ratitae." While I agree with Salvadori's implicit 
thesis— that the downy plumages of birds may be of great taxonomic value— I differ with 
his conclusion. Nowhere among the tinamous that I have examined, nor in species whose 
chicks are described by Salvadori, are there patterns resembling those of rheas or any 
other ratite. This evidence, of course, cannot be used to refute the possibility that ti- 
namous may be more closely related to rheas than to any other living taxon, but neither 
does it provide any support for that hypothesis. Whether analyses of other taxa with pre- 
cocial young might suggest alternate relationships for the Tinamiformes (e.g., Galli- 
formes, see Verheyen, 1960; Chandler, 1916) is problematical but worthy of investigation. 

ACKNOWLEDGMENTS 

Specimens used in this study were borrowed from or examined at tiie American Museum of Natural His- 
tory, Carnegie Museum, The University of Kansas Museum of Zoology, The University of Michigan Museum of 
Zoology, Peabody Museum, Museum of Vertebrate Zoology, Field Museum of Natural History, Philadelphia 
Academy of Sciences, Los Angeles County Museum, and San Diego Natural History Museum. I am indebted to 
the curators of these collections for their assistance. I am also grateful to K. C. Lint and James Dolan for mak- 
ing the facilities of the San Diego Zoo available to me. 

K. C. Parks, R. W. Storer. J. Strauch, G. A. Clark, Jr., W. Bock, P. Devillers, and J. Cracraft provided use- 
ful criticisms of the manuscript. 

LITERATURE CITED 

Beebe, W. 

1925. The Variegated Tinamous Crypturus variegatus variegatus (Gmelin). Zoologica 6(2): 195-227. 
Bock, W. J. 

1963. The cranial evidence for ratite affinities. Proc. XIII Intern. Ornithol. Cong.: 39-54. 
Boetticher, H. von. 

1934. Beitrage zu einem phylogenetisch begrundeten naturlichen System der Steisshuhner (Tinami) auf 
Grund einer taxonomisch verwarbaren Charaktere. Jenaische Zeits. fur Naturwiss. 69: 169-192. 
Brodkorb, P. 

1963. Catalogue of fossil birds. Bull. Florida State Mus. 7(4): 179-293. 



1971 JEHL: RATITES ANDTINAMOUS 301 

Chandler, A. C. 

1916. A study of the structure of feathers, with reference to their taxonomic significance. Univ. California 
Publ. Zool. 13(11): 243-446. 
de Beer, G. 

1956. The evolution of ratites. Bull. Brit. Mus. (Nat. Hist), Zool. 41: 59-70. 

1964. Ratites, phytogeny of the, p. 681-685. In A. L. Thomson (ed.), A new dictionary of birds. McGraw- 
Hill, New York. 

Delacour, J., and E. Mayr. 

1945. The family Anatidae. Wilson Bull. 57: 3-55. 
de Schauensee, R. M. 

1966. The species of birds of South America with their distribution. Livingston Publ. Co., Narberth, Penn- 
sylvania, 577 p. 
Glenny, F. H. 

1965. Main cervical and thoracic arteries of some flightless birds. Ann. Zool. 5(1): 1-8. 
Jehl, J.-R., Jr. 

1968. Relationships in the Charadrii (shorebirds): a taxonomic study based on color patterns of the downy 
young. San Diego Soc. Nat. Hist. Memoir 3. 
Miranda-Ribiero, A. de. 

1938. Notas ornithologicas (XIII). Tinamidae. Rev. do Mus. Paulista 23: 667-788. 
Oliver, W. R. B. 

1957. New Zealand birds. 2nd ed. A. H. and A. W. Reed, WeHington, N. Z. 661 p. 
Parkes. K. C, and G. A. Clark, Jr. 

1966. An additional character linking ratites and tinamous, and an interpretation of their monophylv. Con- 
dor 68: 459-471. 

Peters, J. L. 

1931. Check-list of birds of the world. Vol. 1. Harvard University Press, Cambridge, Mass. 345 p. 
Rand, A. L., and E. T. Gilliard. 

1967. Handbook of New Guinea birds. Wiedenfeld and Nicholson, London. 612 p. 
Salvadori, T. 

1895. Catalogue of Chenomorphae (Palamedeae, Phoenicopteri. Anseres), Crypturi, and Ratite in the col- 
lection of the British Museum. Brit. Mus. (Nat. Hist.), London. 
Sauer, E. G. P., and E. M. Sauer. 

1966. The behavior and ecology of the South African ostrich. Living Bird. Fifth Annual, p. 45-47. 
Short, L. L., Jr. 

1967. A review of the genera of grouse (Aves, Tetraoninae). Amer. Mus. Novitates 2289. 
Sibley, C. G. 

1960. The electrophoretic patterns of avian egg-white proteins as taxonomic characters. Ibis 102: 215-284. 
Storer, R. W. 

1967. The patterns of downy young grebes. Condor 68: 469-478. 
Verheyen, R. 

1960. Les Tinamous dans les systemes omithologiques. Bull. Inst. Roy. Sci. Nat. de Belgique 36( 1): 1-11. 
Ward, R. A. 

1957. A study of the host distribution and some relationships of mallophaga parasites on birds on the Order 
Tinamiformes. Part I. Ann. Ent. Soc. Amer. 50: 335-353. 



San Diego Natural History Museum, P. O. Box 1390, San Diego, California 92112 




J/1U:d. CuiviP. ^.k^u; 
LIBRARY 

FEB 1 8 1972 

HARVARD 
UNIVERSITY 



CENOZOIC CALCAREOUS NANNOFOSSILS 
FROM THE PACIFIC OCEAN 



DAVID BUKRY 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 

VOL. 16, NO. 14 7 DECEMBER 1971 



CENOZOIC CALCAREOUS NANNOFOSSILS 
FROM THE PACIFIC OCEAN 

DAVID BUKRY 



ABSTRACT.— The typical stratigraphic ranges of key Cenozoic calcareous nannofossil taxa in Pacific 
Ocean cores are presented. Two new genera and 16 new species from Pacific Ocean cores are described; 
these include: CoccoUihus magnicrassus. C. miopelagicus. Coccolithus? orangensis. Cyclicargolithus n. gen., 
Cvcloliihella kariana. Discoaster bifax. D. intercalaris, D. loehlichii. D. neorectus, Fasciciilithiis clinalus. He- 
licoponiosphaera heezcnii, H. rhomba. Sphenolithus coniciis, S. obtiisus, S. spiniger, Strialococcolilhus n. 
gen., Siriatococcolithus pacificanus, and Triquetrorhabdulus milowii. 

INTRODUCTION 

Calcareous nannofossils are microscopic calcite skeletal elements produced largely 
by Coccolithophyceae— marine, planktonic, one-celled, golden-brown algae. These 1-50 
micron skeletal elements, composed of many still smaller calcite crystallites, have been 
preserved in marine strata since their earliest known occurrence in deposits of Early Ju- 
rassic age. Owing to their great abundance and evolutionary structural diversification, 
nannofossils can be used to subdivide marine strata into a sequence of biostratigraphic 
zones. The planktonic life-style of fossil nannoplankton in the light-penetrated and there- 
fore current-influenced layer of the ocean ensured rapid dispersal of new forms. This fac- 
tor contributes to the utility of nannofossils in transoceanic stratigraphic correlation. 

Light microscopes set at magnifications of 250-1000 X and electron microscopes at 
1000-20,000 X are used in the identification of nannofossils. For rapid comparison of 
many samples and for stratigraphic zonation utilizing assemblages, the light microscope is 
most convenient. For delineation of detailed surficial crystallite patterns that aid in phy- 
logenic and taxonomic studies, the electron microscope is useful. But the internal crystal- 
lographic orientation of the individual crystallites provides important distinctions for 
taxonomic discrimination, and this information comes only from cross-polarized light mi- 
croscopy. 

Approximately 3000 species of Cenozoic nannofossils have been described. The most 
important forms for zonation are the star-shaped discoasters, the placoliths (shaped like 
sewing-machine bobbins), and the cone-shaped sphenoliths (examples in Plate 1). Tax- 
onomic distinctions within these groups are based for discoasters on the number and form 
of the rays and on accessory ornamentation of the rays and central area as seen in plan 
view; for placoliths on the crystallite crystallographic orientation, on relative proportions 
and circularity of the central area and rims of the upper and lower shields, and on any 
distinctive central-area ornamentation; for sphenoliths on the orientation of basal and 
apical spines as seen in cross-polarized light at various angles to the polarization. 

ZONATION 

The potential of calcareous nannofossils for biostratigraphic zonation was first in- 
dicated by Bramlette and Riedel (1954), and in 1967 the first general sequence of Ceno- 
zoic calcareous nannofossil zones was published (Bramlette and Wilcoxon, 1967; Hay et 
al., 1967). These zones were based on study of stratigraphic type stages in Europe, the Ci- 
pero and Lengua Formations of Trinidad, long cored sequences from the JOIDES Blake 
Plateau drilling, and numerous short cores taken on oceanographic expeditions. This 
tYamework has provided useful guidelines for later studies based on the Deep Sea Drilling 
Project cores and on restudy of type-stage sections using the ranges of many newly de- 
scribed species. Recent studies furthering zonal refinement include: Gartner, 1969, 1971; 



SAN DIEGO SOC. NAT. HIST.. TRANS. 16 (14): 303-328, 7 DECEMBER 1971 



304 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Bukry and Bramlette, 1970: Milow, 1970; Roth, 1970; Bukry, 1971; and Martini and 
Worsley, 1971. Because nannofossils are small and occur in vast numbers in a given 
sample, the whole assemblage can be scanned in a few minutes. Therefore, it is conven- 
ient to base zonal identifications on the character of the whole assemblage. Boundaries of 
zonal units (table 1) can usually be identified by closely spaced first and last occurrences 
of several species. Some of the key species used to recognize zone and subzone boundaries 
are indicated in tables 2 and 3. A full discussion of the character of these zonal units is 
given in the report on nannofossil stratigraphy for Deep Sea Drilling Project Leg 16 that 
explored the eastern equatorial Pacific Ocean (Bukry, in press). 

NANNOFOSSIL DISSOLUTION 

The diversity of species that compose nannoplankton assemblages is, to a large ex- 
tent, controlled by selective dissolution of skeletal elements between the time of death in 
surface water and the time of final burial below the ocean bottom. Skeletal elements that 
bypass or survive ingestion by nannoplankton herbivores— microscopic, planktonic proto- 
zoans such as foraminifers and radiolarians (Tappan, 1971)— owing to their calcite com- 
position are subjected to increased inorganic dissolution rates in progressively more 
calcite-undersaturated water at progressively greater ocean depth (Peterson, 1966). Al- 
though Berger (1970) has estimated that about four-fifths of the calcite supphed to the 
ocean floor is being redissolved, nannoplankton skeletons are more resistant to this effect 
than are other calcite microplankton skeletons. Part of their resistance to dissolution may 
be the result of incorporation of acid-resistant, fibrillar, cellulose-like polysaccharide ma- 
terial with the skeletal calcite (Franke and Brown, 1971). Chave and Suess (1967) have 
stated that organic coatings inhibit the precipitation of calcium carbonate on carbonate 
surfaces. Such coatings that inhibit carbonate-sea water interactions probably also retard 
dissolution of calcium carbonate particles in undersaturated water (Smith et al., 1968; 
Pytokowicz, 1969). 

In addition to the possible organic coatings, variation in nannoplankton skeletal 
thickness relative to optic-axis orientation apparently accounts for some of the solution 
resistance of nannoplankton. Some of the most resistant taxa have a similar relation be- 
tween the exposed surfaces and optic-axis orientation of their calcite crystallites. Dis- 
coaster and the upper shields of the placoliths Coccolithus and Cvclococcolithina are 
typically the last remnants of a strongly dissolved fossil nannoplankton assemblage. In 
cross-polarized light, all of these appear dark because of the vertical orientation of the 
principal optic axis of their crystallites. Diff'erences in dissolution rates along dilTerent 
crystallite axes, in conjunction with variation in crystallite thickness, could cause a signifi- 
cant range of structural differences to explain selective solution along taxonomic group- 
ings. 

The most diverse assemblages, those from warm-water areas that are little affected 
by calcite undersaturation, occur in deposits from the sublittoral shelf to the basal conti- 
nental slope (approx. depths 50-2000 m). Such assemblages, which may contain common 
pentagonally-shaped Braarudosphaera or Micrantholithus (JOIDES Blake Plateau cores, 
for example), have been characterized as "nearshore'' (Bramlette and Martini, 1964). As 
these nannoplankton are distinctively shaped, their general absence in deep-ocean (2000- 
6000 m) sediment is easy to determine. Indeed, some of these presumed nearshore in- 
dicator taxa have been reported in mid-ocean plankton and island samples, for example, 
Braarudosphaera in North Atlantic water (Hulburt, 1962; Hulburt and Rodman, 1963) 
and Braarudosphaera and Micranihohthus in shallow-water sediment from the Tonga Is- 
lands (Bramlette, 1970), suggesting that they are not restricted to inshore areas by envi- 



1971 



BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 



305 



ronmental factors while they are alive. Instead, these forms are probably poorly resistant 
to solution. Their spotty and far-flung distribution suggests that they are preserved in 
shallow (near-saturated) depositional areas and dissolved in deep (undersaturated) areas. 

Table 1. Cenozoic calcareous nannoplankton zones and subzones. Approximate ages of series and subseries in 
million years from Berggren ( 197 1 ). 



SERIES OR 

SUBSERIES 


AGE 
M. Y. 


ZONE 


SUBZONE 


HOLOCENE 


0.01 

1.85 
3.7 

5.1 

- 10.5 

- 14 

- 22.5 

- 38 

- 45 

- 49 

- 53.5 

- 65 


Errrlliania huxleyi 






Gephyroaapsa oaeaniaa 


PLEISTOCENE 


Cocaolithus doroniooides 


Gephyrocapsa aaribbeaniaa 




Emiliania annula 


UPPER 
PLIOCENE 


Disaoaster brouueri 


Cyaloaoaaolithina maaintyrei 


Disaoaster pentaradiatus 


Disaoaster tamalis 




Re tiouto fenestra pseudownbilioa 


Disaoaster asyrnmetriaus 


LOWER 


Sphenolithus neoabies 


PLIOCENE 


Ceratotithus trioorniculatus 


Ceratolithus rugosus 




Ceratolithus amplifiaus 




Triquetrorhabdulus rugosus 




Disaoaster quinqueramus 


Ceratolithus primus 


UPPER 


Disaoaster berqgrenii 


MIOCENE 


Disaoaster neohamatus 


Disaoaster neoreatus 




Disaoaster bellus 




Disaoaster hamatus 


MIDDLE 


Catinaster aoatitus 


MIOCENE 


Disaoaster exitis 


Disaoaster kugleri 




Cocaolithus miopelagiaus 




Sphenolithus heteromorphus 




Heliaopontosphaera ampliaperta 


LOWER 


Sphenolithus belemnos 


Triquetrorhabdulus aarinatus 


Disaoaster druggii 


MiOCENb 


Disaoaster deflandrei 




Diatyoaoaaites abisectus 




Sphenolithus aiperoensis 


OLIGOCENE 


Sphenolithus distentus 


Sphenolithus predistentus 




Heliaopontosphaera retiaulata 


Cyaloaoaaolithina formosa 




Cocaolithus subdistichus 


UPPER 


Disaoaster barbadiensis 


Cyaliaargolithus reticulatus 


EOCENE 


Disaoaster tani tani 




Retiaulofenestra umbiliaa I 




Nannotetrina quadrata 


Cocaolithus staurion 


MIDDLE 


Chiasmolithus gigas 


EOCENE 


Disaoaster mirus 




Disaoaster sublodoensis 




Disaoasteroides kuepperi 




Disaoaster lodoensis 


LUwhK 


Tribraahiatus orthostylus 


EOCENE 


Disaoaster diastypus 




Disaoaster multiradiatus 


Campy losphaera eodela 




Chiasmolithus bidens 




Disaoaster nobilis 


PALEOCENE 


Disaoaster mohleri 




Heliolithus kleinpellii 




Fasaiaulithus tympaniformis 




Cruaiplaaolithus tenuis 




1 
. — J 



306 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



Comparison of fossil nannoplankton assemblages from Deep Sea Drilling Project 
cores taken from many ocean depths shows that the most solution-resistant genera— Z)/5- 
coaster, Coccolithiis, Cyclococcolithina, Reticulofenestra, and Dictyococcites—occ^xx in 
nearly all samples, shallow and deep. In fact, these taxa persist in some deep-ocean red- 
clay deposits after all other calcitic microfossils have been dissolved. On the contrary, 
such taxa as Braanidosphaera, Micrantholithus, Transversopontis, Scyphosphaera, and He- 
licopontosphaera are absent from red-clay deposits. By comparing many different coeval 



Table 2. 
dashed. 



Typical ranges of some key late Cenozoic calcareous nannoplankton. Rare or sporadic occurrence 



MIOCENE 



PLIOCENE 



PLEISTOCENE > 
AND HOLOCENE M 



C3'3<3Co&:Coejt)rit)t)t)i3o^<^<^<J3t)t)t3r^triQ:i£::i ct] 



ft U5 



ft 

ft 



TO 

o 
3 
o 

/s 
ha 

s- 
s; 

Co 



3 

O 
h3 

TO 

ft 

K 

Co 






S" 



iyxj 



o 

Co 



TO 
s 

d- 

ft 

^S 

ft 

ft. 

r>. 

ft 

<M- 

s; 

Co 




Emiliania huxleyi 



Gephyrocapsa oceaniaa 



G. aaribheaniaa 



Ceratolithus cristatus 

Cyctoaoccolithina maaintyrei 

Ceratolithus rugosus 

Discoaster brouweri 

D. pentaradiatus 

D. sur cuius 

D. asymmetricus 

D. tamalis 

D. variabilis decorus 

Reticulofenestra pseudoumbiliaa 
Sphenolithus neoabies 



Ceratolithus tricomiculatus 



C. amplificus 



C. primus 



Triquetrorhabdulus rugosus 
Discoaster quinqueramus 



D. berggrenii 



D. neorectus 



D. neohamatus 



D. bellus 



D. hamatus 



Catinaster coalitus 



Discoaster exilis 



Discoaster kugleri 



Coccolithus miopelagicus 

Sphenolithus heteromorphus 

Cyclicargolithus floridanus 
Helicopontosphaera ampliaperta 
Sphenolithus belemnos 



Discoaster druggii 



Triquetrorhabdulus carinatus 
Dictyococcites abisectus 



1971 



BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 



307 



assemblages, a general order of selective solution can be determined that reflects the rela- 
tive depth of ancient ocean areas. The following list ranks lower Cenozoic nannofossil 
genera from those least common in deep-ocean sediment, at the beginning, to those most 
characteristic of very deep sediment at the end: Transversopontis, Syracosphaera, Rhab- 
dosphaera, Discolithina [perforate], MicranthoUthiis, Braarudosphaera, Lophodolil/ms, 
Scvphosphaera, Helicopontosphaem, Discolithina [imperforate], Sphenolithus, Chiasmo- 
lithus, Reticulofenestra, Dictyococcites, Cyclococcolithina, Coccolithus, Discoaster. 

Coeval samples from two nearby Pacific Ocean sites of greatly differing water depth 
are cited below as specific examples of taxonomically selective dissolution. Assemblages 
from the deep-water site of the pair are always less diverse. The species common to both 
the shallow site (DSDP 62: depth 2591 m, lat 1°52.2'N., long 141°56.0'E.) and the deep 
site (DSDP 63: depth 4472 m, lat 0°50.2'N., long 147°53.5'E.), are excluded, and the taxa 
listed below for each geologic subseries and zone are those solution-prone forms that oc- 

Table 3. Typical ranges of some key early Cenozoic calcareous nannoplankton. 



PALEOCENE 


EOCENE 


OLIGOCENE 


AGE 


TO 
S 
K 

Co 


• 

1 
ft 
s 

Co 


• 

TO 
TO 


1 

S" 
TO 

>^ 


s 
o 

^. 

Co 


cy 

ft. 
TO 
3 
Co 


pi 

TO 
O 

TO 
^~» 
ft 


a. 
ft 

Co 

n- 

Co 


O 

Co 

s; 

Co 


t3 

O 

TO 
S 
Co 

Co 


?^ 
K 

TO 
t3 

TO 
"^ 


Co 
S 

C3- 
^^ 

o 

§^ 

TO 
S 
Co 

Co 


3 

Co 


Co 


Co 

ri- 
ft 

^. 
O 


to 

c;) 
ft 


t3 

ri- 
ft 
S 

rf 
ft 
S 


TO 

C1- 

Ci 
K 

ft 

n- 

Co 


p 

Co 

s; 

C3^ 

r^. 

Co 
<r1- 

Ci 

Co 


pi 

i 

Co 

a 


Co 

13 

TO 
C^ 
r^ 
Co 

rl- 

TO 

n- 
K 

Co 


Co 

ft. 

Co 
TI- 
TO 

s 

d- 
Co 


"C 
TO 

O 

TO 
S 
Co 

Co 


Cfi tsi / 
GOO / 

ro » z / 

O / o 

Z / en Q 

w / Tj n 

/ wo 

/ no 

/ M f 
/ MM 

/ Crt H 

/ ^ 


X 


X 
X 


X 
X 
X 
X 


X 
X 
X 


X 
X 
X 
X 


X 
X 
X 
X 
X 


X 
X 
X 


X 
X 


X 
X 

X 
X 
X 


X 
X 

X 
X 
X 


X 

X 
X 

X 

X 
X 
X 


X 

X 
X 
X 

X 
X 
X 


X 

X 
X 
X 
X 

X 


X 

X 
X 
X 
X 
X 
X 


X 

X 
X 
X 
X 


X 
X 

X 
X 


X 
X 
X 
X 

X 


X 
X 
X 
X 

X 
X 


X 
X 
X 
X 
X 


X 
X 

X 

X 


X 
X 


X 


X 
X 


Sphenolithus aiperoensis 
Diatyoaoaaites abiseatus 
Sphenolithus distentus 
Discoaster tani tani 
Sphenolithus predistentus 


Reticulofenestra umbiliaa 


Cyclococcolithina formosa 


Coccolithus subdistichus 
Cyclicargolithus reticulatus 


Discoaster barbadiensis 


Chiasmolithus grandis 


Coccolithus staurion 


Nannotetrina quadrata 


Chiasmolithus gigas 
Discoaster mirus 


D. sublodoensis 


Rhabdosphaera inflata 


Coccolithus crassus 


Discoasteroides kuepperi 


Discoaster lodoensis 


Tribrachiatus orthostylus 


Discoaster diastypus 


Campy losphaera eodela 


Discoaster multiradiatus 


D. nobilis 


D. mohleri 


Chiasmolithus bidens 


Fasciculithus tympaniformis 


Heliolithus kleinpellii 


Cruaiplacolithus tenuis 





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1971 BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 309 

cur at the shallow site alone. 

Lower Pleistocene Coccolithus doronicoides Zone: 

Discoaster perplexus, Helicopontosphaera sellii, Oolithotus antillarum, Rhabdosphaera 
clavigera, Umbilicosphaera mirahilis. 

Upper Pliocene Discoaster brouweri Zone: 

Discoaster perplexus, Helicopontosphaera sellii, Oolithotus antillarum, Scyphosphaera 
apsteinii, S. intermedia, Thoracosphaera spp. 

Lower Pliocene Ret iculo fenestra pseudoumbilica Zone: 

Discoaster perplexus, Discolithina japonica, Helicopontosphaera kamptneri, H. sellii, 
Oolithotus antillarum, Scyphosphaera apsteinii, S. globulata, S. pulcherrima, Thora- 
cosphaera spp. 

Upper Miocene Discoaster quinqueramus Zone: 

Discoaster perplexus, Discolithina japonica, Helicopontosphaera kamptneri, Scyphos- 
phaera intermedia, Sphenolithus abies, Thoracosphaera spp. 

Middle Miocene Discoaster hamatus Zone: 

Discoaster perplexus, Helicopontosphaera kamptneri, Scyphosphaera sp. cf. 5". pulcher- 
rima, Sphenolithus abies. 

Establishing the relative order of nannofossil dissolution is important to provide in- 
formation for interpretating the paleoecology of the assemblages (Douglas. 1971; Law- 
rence, 1971), and to improve precision in stratigraphic zonation. 

SYSTEMATIC PALEONTOLOGY 

Genus Coccolithus Schwarz, 1894 

Coccolithus magnicrassus n. sp. 

PI. 2, figs. 1-5 

Description.— This large, elliptic placolith is characterized by a small central area and 
a broad finely striate rim. In light-microscope examination, the central area is prominent 
and the rim faint, being at high and low relief with respect to the mounting medium 
(n= 1.518). In cross-polarized light the central area is bright, forming a small elliptic col- 
lar around an elliptic central opening: whereas the rim is faint, with diffused strongly 
curving extinction bands. The upper rim has 55-80 radial crystallites, and is distinctly 
larger than the lower rim. 

Remarks.— Coccolithus magnicrassus is distinguished from other similar placoliths by 
the combined characters of (1) large overall size; (2) small, high relief central area with 
simple central opening; (3) broad upper rim, composed of many elements, that is only 
moderately bright in cross-polarized light and has diffuse, strongly curving extinction 
bands. Toweius craticulus Hay and Mohler is smaller with a narrower rim; Reti- 
culofenestra hillae Bukry and Percival has a larger central opening and in cross-polarized 
light a fully bright rim with broader less curved extinction bands; Coccolithus crassus 
Bramlette and Sullivan is distinctly smaller, and the upper, larger rim is dark in cross- 
polarized light. A comparison of C. crassus with C. magnicrassus is shown in PI. 2, fig. 2. 

Plate I. Electronmicrographs of carbon-platinum replicas showing surface crystallite patterns of some typical 
forms of Cenozoic calcareous nannofossils. 1. Svracosphaera pulchra Lohmann, Pleistocene, Shatsky Rise, 
DSDP 47.0-1-4, 77-78 cm. 11,000 X. 2. Helicoponiosphaera kamptneri Hay and Mohler, Pleistocene, Shatsky 
Rise. DSDP 47.0-1-4, 77-78 cm. 7,000 X. Diatom fragment at lower right corner. 3. Rhabdosphaera clavigera 
Murray and Blackman, Pleistocene, Shatsky Rise, DSDP 47.0-1-4, 77-78 cm. 8,000 X. 4. Group of placoliths 
and discoasters. Pliocene, Caroline Ridge. DSDP 57.2-1-6, 0-3 cm. 1,700 X. 5. Group of placoliths and a dis- 
coaster. Miocene, Caroline Ridge, DSDP 55.0- 1 1-5, 78-80 cm. 4,000 X. 6. Group with placolith, discoaster, and 
sphenolith. Eocene, Horizon Ridge, DSDP 44.0-3-5, 145- 150 cm. 3,000 X. 



310 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Occurrence.— Coccolithus magnicrassus occurs in lower Eocene marine sediment 
cored in the North Pacific and North Atlantic Ocean and in the Donzacq Marl of France. 
It does not range as high as C. crassus, for it is recognized only from the Discoaster lo- 
doensis Zone thus far. 

^/ze. — 16-20 microns. 

Holotvpe.-\JS^U 176883 (PI. 2. figs. 1-2). - 

Paratvpe.-\J'S^M 176884-176886. 

Type locality.-\:>^D? 47.2-7-3, 104-105 cm, Shatsky Rise, northwestern Pacific 

Ocean. 

Coccolithus miopelagicus n. sp. 

PI. 2, figs. 6-9 

Description.— This large placolith has a medium-sized central area and a broad dis- 
tinctly striate rim. In light-microscope examination, both the rim and central area are 
prominent. In cross-polarized hght the central area is bright with distinct extinction 
bands; the lower (smaller) rim is bright, but the upper rim is dark. A small simple ellipti- 
cal opening or sht in the central area is aligned with the long axis of the placolith. 

Remarks.— The similarly constructed species, Coccolithus eopelagicus (Bramlette and 
Riedel) is distinguished from Coccolithus miopelagicus by several criteria: (1) Rim counts 
for C. eopelagicus are higher, 50 to 61 instead of 40 to 49; (2) Measurement often typical 
specimens shows that the central area of C. eopelagicus occupies a greater percentage of 
the long axis, 59+ 1 percent instead of 50 + 5 percent; (3) The central area also occupies a 
greater percentage of the short axis, 49 + 2 percent instead of 42 + 3 percent. The general 
distinction of C. miopelagicus from C. eopelagicus and large specimens of the younger C. 
pelagicus (Wallich) s.s. is the distinctly smaller central area of C. miopelagicus with respect 
to the rim area. Large specimens of C miopelagicus are 20 microns in major axis length, 
but as indicated by Bramlette and Riedel (1954) these middle Tertiary forms, similar to C. 
eopelagicus. are generally smaller. 

Occurrence.— Coccolithus miopelagicus is most common in lower and middle Miocene 
sediment from the Atlantic and Pacific Oceans and Caribbean Sea. The appearance of C. 
miopelagicus populations near the Oligocene- Miocene boundary is probably a gradual 
transition from C. eopelagicus resulting from increasing temperatures. Some tropical 
middle Eocene C. eopelagicus populations have a fair percentage of associated C. sp. cf. 
C. miopelagicus, whereas lower Oligocene (cooler temperatures) and high latitude middle 
Eocene assemblages contain only C. eopelagicus. The disappearance of C. miopelagicus at 
the Catinaster coalitus Zone is abrupt. 

Size. — \2> to 18 microns. 

Holotvpe.-\JS^U 176888 (PI. 2, figs. 7-8). 

ParatYpe.-\]?>^U 176887, 176889. 

Type /ofa//7v.— DSDP 63.0-3-4, 80-81 cm. East Caroline Basin, western equatorial 
Pacific Ocean. 

Plate 2. Photomicrographs: 2,000 X. 1-5. Coccolithus magnicrassus. n. sp. ( 1) holotype USNM 176883, DSDP 
47.2-7-3, 104-105 cm; (2) holotype at left, Coccolithus crassus Bramlette and Sullivan at right, cross-polarized, (3) 
USNM 176884, (4) USNM 176885, cross-polarized, (5) USNM 176886, DSDP 47.2-7-2, 100-101 cm, cross-polar- 
ized. 6-9. Coccolithus miopelagicus, n. sp. (6) USNM 176887, DSDP 63.1-8-3, 80-81 cm. (7) holotype USNM 
176888, DSDP 63.0-3-4, 80-8f cm, (8) holotype, cross-polarized, (9) USNM 176889, DSDP 70.0-3-3. 63-64 
cm. 10-11. Coccolithus? orangensis, n. sp. (10) holotype USNM 176890, DSDP 55.0-13-1, 120-121 cm, (11) 
holotype, cross-polarized; three small Cvclicargolithus sp. cf. C floridamts (Roth and Hay) with straight extinc- 
tion lines are present below the holotype. 



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312 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Coccolithus? orangensis n. sp. 

PL 2. fig. 10; PI. 3, figs. 1-3 

Description— This small elliptic placolith has exceptionally high relief with respect to 
the mounting medium (n= 1.518). Individual crystallites are not discernible by light mi- 
croscope. In cross-polarized light, the coccolith is bright except for a small central open- 
ing. The extinction bands are strongly curved and become abruptly diffused in a narrow 
margin at the outer perimeter that is slightly brighter than the rest of the nannofossil. 

Remarks.— Coccolithus? orangensis is not readily assignable to any presently de- 
scribed genus. What might be a side view of this species is shown at the right side of fig- 
ure 1-2 of Plate 3. The exceptionally high relief, characteristically exceeding that of 
discoasters, small size, and bright perimeter help to distinguish C? orangensis from other 
elliptic nannofossils. There appears to be a narrow, high relief collar structure around the 
small central opening, resulting in a ring-like depression between the perimeter and col- 
lar. C? orangensis is distinguished from Cyclicargolithus fhridanus (Roth and Hay) by its 
elliptic outline, high relief, and bright perimeter. 

Occurrence.— Coccolithus? orangensis is never abundant but is a consistent low-fre- 
quency member of upper Oligocene and lower Miocene assemblages assigned to the 
Sphenolithus ciperoensis Zone and Triquetrorhahdulus carinatus Zone. It occurs in both 
Pacific and Atlantic Ocean deep-sea cores. 

Size.— A to 6 microns. 

Holot\pe.-\JS^U 176890(P1. 2, figs. 10-11). 

Paratypes.-\JSNU 176891-176892. 

Type locality — DSDP 55.0-13-1, 120-121 cm, Caroline Rise, western equatorial Paci- 
fic Ocean. 

Cyclicargolithus n. gen. 

Description.— CirculaT to subcircular placoliths constructed of two shields connected 
by a central tube that may be closed or open. In plan view, the upper shield is bright in 
cross-polarized light. 

Type species.— Coccolithus floridanus Roth and Hay in Hay and others, 1967, Gulf 
Coast Assoc. Geol. Socs. Trans., v. 17, p. 455, PI. 6, figs. 1-4. 

Remarks.— J\\Q genus Cyclococcolithina Wilcoxon (1970) included circular to sub- 
circular forms of two kinds— those with dark upper shields and those with bright upper 
shields when viewed in cross-polarized light. The significant difference in the orientation 
of the optic axis of the shield crystallites that accounts for this distinction is considered to 
be of generic rank. Therefore Cyclococcolithina Wilcoxon is herein restricted to those 
forms having dark upper shields such as Cyclococcolithina formosa and the type species 
Cyclococcolithina leptopora. Forms with bright upper shields are transferred to Cycli- 
cargolithus. The circular to subcircular outline of this genus distinguishes it from elliptical 
Coccolithus Schwarz, which has a dark upper shield in cross-polarized light. 

Cyclicargolithus floridanus (Roth and Hay) n. comb. 

Coccolithus floridanus Roth and Hay in Hay and others, 1967. Gulf Coast Assoc. Geol. Socs. Trans. 17: 455. PI. 

6, figs. 1-4. 
Cyclococcolilhus neo^ammalion Bramlette and Wilcoxon, 1967. Tulane Studies Geol. 5: 104. PI. 1. figs. 1-3; PI. 4, 

figs. 3-5. 
Cvclococcolilhus floridanus (Roth and Hay), ot^ Mulier, 1970. Geologica Bavarica 63: 1 13, PI. 2, figs. 1-3. 
Cyclococcolithus fhridanus {Roth and Hay), of Roth. 1970, Eclogae Geo!. Helv. 63: 854, PI. 5, fig. 6. 

^£'m^//A:.v.— The original definition of Coccolithus floridanus Roth and Hay describes a 
small (3.6 to 5 micron) eUiptic placolith. The original definition of Cyclococcolithus neo- 



1971 BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 313 

gammation Bramlette and Wilcoxon describes a medium sized (6 to 12 micron) circular 
placolith. According to Roth ( 1970) the electronmicrograph paratypes of these two species 
show the same construction and number of rim elements. The slight difference in size and 
shape noted in the written descriptions probably resulted from the description of end 
members of the same species and from the use of different instrumentation. 

CvcIicargoUthiis luminis (Sullivan) n. comb. 

Cvclococcolithus luminis Sullivan. 1965, Univ. Calif. Puhi. Geol. Sci. 53: 33, PI. 3, figs. 9a, b. 

CyclicargoUthus reticulatus (Gartner and Smith) n. comb. 

Cvclococcolithus reticulatus Gartner and Smith, 1967, Univ. Kansas Paleont. Contr., Paper 20, p. 4, PI. 5, figs. I- 
4.' 

Genus Cvclolithella Loeblich and Tappan, 1963 
Cyclolithella kariana n. sp. 

PI. 3. figs. 4-5 

Description.— J\\\s small circular coccolith has a small circular central opening that 
occupies about a quarter to a third of the diameter. The thick upper shield is composed of 
about 12 to 20 curving crystallites that are strongly imbricated, indicated by the spiralling 
effect as focus is raised or lowered through the coccolith. The margin of the central open- 
ing and outer perimeter is generally smooth, but the perimeters of a few etched(?) speci- 
mens appear slightly scalloped. In cross-polarized light, no sharp black extinction bands 
are seen; instead, four light-gray rays each occupy two or three crystallites. 

Remarks.— Cyclolithella kariana is distinguished from other species of Cvclolithella by 
the small central opening. It is further distinguished from the most similar species, Cvcl- 
olithella pactilis Bukry and Percival, by curved, gray extinction bands instead of straight 
black ones, when viewed in cross-polarized light. 

Occurrence.— Cvclolithella kariana occurs commonly in lower Eocene sediment as- 
signed to the Discoaster lodoensis Zone at DSDP 47.2 on the Shatsky Rise of the north- 
western Pacific Ocean. 

Size.— 6 to 9 microns. 

Holotvpe.-VSl<\M 176893 (PI. 3. figs. 4-5). 

Type' locality.-DSDP 47.2-7-3, 104-105 cm, Shatsky Rise, northwestern Pacific 
Ocean. 

Genus Discoaster Tan, 1927 
Discoaster bifax n. sp. 

PI. 3. figs. 6-11 

Description.— This small species is constructed of 10 to 15 (typically 14) approx- 
imately radial rays that are appressed and terminate in broad points. High central stems 
extend from each side of the discoaster. The stem on one side is slender, occupying only 
25 percent of the shield diameter, whereas the stem on the other side is consistently twice 
as wide, occupying 50 percent of the shield diameter. No birefringence is seen in cross- 
polarized light. 

Remarks.— Discoaster bifax is distinguished from other compact discoasters, Dis- 
coaster barbadiensis Tan, D. circularis Hoffmann, D. multiradiatus Bramlette and Riedel, 
D. saipanensis Bramlette and Riedel, and D. salisburgensis Stradner, by tall central stems 



314 



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1971 BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 315 

on both sides of the discoaster shield instead of only on one side. It is distinguished from 
other double-stemmed forms such as D. diastypus Bramlette and Sullivan and D. bollii 
Martini and Bramlette by stems of strongly contrasting width on opposite sides of the 
same specimen. 

Occurrence.— Discoaster bifax occurs commonly in Stetson 21 at 147-152 cm from the 
Atlantic Ocean. Associated nannofossils in this sample such as Chiasmolithus grandis 
(Bramlette and Riedel) and Reticulofenestra umbilica (Levin) indicate a middle Eocene 
age. D. bifax is sparse in coeval Pacific Ocean sediment from the Reticulofenestra umbilica 
Zone of the East Pacific Rise, DSDP 74.0-12-3, 24-25 cm. 

Size.— 5 to 10 microns. 

Holotvpe.-VSNM 176895 (PI. 3, figs. 7-8). 

Paratvpes.-VSNM 176894. 176896-176897. 

T}pe locality: Stetson 21, 147-152 cm, northwestern Atlantic Ocean. 

Discoaster intercalaris n. sp. 

PI. 3, fig. 12; PI. 4, figs. 1-2 

Discoaster brouweri Tan, of Stradner and Papp, 1961, (partim). Jahrb. Geol. Bundesanst. [Wien], v. 7, p. 85, PI. 
20, fig. 6. 

Description.— This medium-sized, six-rayed species has a large central area and a cen- 
tral stem. The symmetric radially arrayed rays show a distinct tapering and terminate in 
simple rounded points. Some specimens have a small indentation at the tip. 

Remarks.— Discoaster intercalaris is a simple form that is distinguished from the Dis- 
coaster variabilis group by a single-pointed termination of the rays instead of a broadly 
flaring bifurcation. It is distinguished from Discoaster brouweri brouweri Tan, emended, 
by the wide central area and marked taper of the rays. It is distinguished from Discoaster 
neorectus Bukry by its smaller size and the straight to slightly concave sides of the rays. 

Occurrence.— Discoaster intercalaris is common in upper Miocene to upper Pliocene 
marine sediment cored by the Deep Sea Drilling Project during Leg 5 at sites off" northern 
California. The cool-water aspect of the associated nannofossil assemblages and the sim- 
ilarity in form of D. intercalaris and D. variabilis variabilis suggest that D. intercalaris may 
be a cool-water relative of D. variabilis variabilis that failed to develop bifurcations. This 
possibility is indicated by the small size of the bifurcations of D. variabilis variabilis speci- 
mens associated with D. intercalaris. More southerly populations of D. variabilis variabilis 
have larger, more robust terminations (see Martini and Bramlette, 1963, PI. 104, figs. 4-8). 

Size. — \Q to 16 microns. 

Holotvpe.-\}^^M 176899(P1. 4. fig. 1). 

Paraiypes.-\J'S>NU 176898, 176900. 

Type /oca//7v.— DSDP 36-12-5. 77-78 cm, western flank of Gorda Rise, northeastern 
Pacific Ocean. 

Discoaster loeblichii n. sp. 

PI. 4, figs. 3-5 

Plate 3. Photomicrographs: 2.000 X. 1-3. Coccolithus? orangensis n. sp. (1) USNM 176891, DSDP 74.0-4-4, 
63-64 cm, cross-polarized, plan view on left, (2) same, bright field, (3) USNM 176892, DSDP 77B-37-4, 65-66 
cm. cross-polarized. 4-5. Cvclolithella kariana n. sp. (4) holotype USNM 176893, DSDP 'M. 1-1-7,. 104-105 cm, 
(5) holotype, cross-polarized. 6-11. Discoaster bifax n. sp. (6) USNM 176894, STETSON 21, 147-152 cm, tilted, 
(7) holotype USNM 176895, high focus, (8) holotype, low focus, (9) USNM 176896, tilted, (10) USNM 176897, 
high focus, (11) same, low focus. 12. Discoaster intercalaris n. sp. (12) USNM 176898, DSDP 36-12-5, 77-78 
cm. 



316 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Description.— This small- to medium-sized, six-rayed species has a central area oc- 
cupying about a third of the total discoaster diameter. It has a small central knob, and the 
rays are distinctly tapered, being widest near the central area. The tips of the rays have 
distinctive unequal bifurcations that are bent slightly out of the plane of the rays. Both 
limbs of the bifurcation taper to points, but all six sets show one Umb that is consistently 
more than twice as long as the other. The sense of direction of the resulting asymmetric 
bifurcation is always the same for all six rays of a given specimen. 

Remarks.— Besides Discoaster loeblichii, the only other six-rayed discoaster with or- 
dered, therefore primary, crescent-forming bifurcations is Discoaster calcaris Gartner, 
which is a large form more comparable in size, proportions, and occurrence to five-rayed 
D. hamatiis Martini and Bramlette. Discoaster loebichii is distinguished by a proportio- 
nally larger central area, by shorter, broader, and more tapering rays, and by a smaller 
average size (12 to 16 microns instead of 16 to 22 microns). It appears to have been de- 
rived from the Discoaster variabilis group, and differs from D. variabilis variabilis Martini 
and Bramlette by the unequal bifurcations that form an asymmetric crescent at the ray 
tips. 

Occurrence.— Discoaster loeblichii was a limited stratigraphic range in the early late 
Miocene Discoaster neohamatus Zone, where it is most common in the middle to upper 
part of that zone. Geographically, D. loeblichii is known from the tropical Pacific Ocean 
areas cored during Deep Sea Drilling Project Legs 7 to 9. 

Size. — \ 1 to 16 microns. 

Holotvpe.-XJS^M 176902 (PI. 4, fig. 4). 

Paraiype.-\}^^U 176901, 176903. 

Type locality. —DS>D? 83A-15-6, 130-131 cm, Panama Basin, eastern equatorial Paci- 
fic Ocean. 

Discoaster neorectus n. sp. 

PL 4, figs. 6-7 

Description.— This gigantic six-rayed species has a small central stem but no sepa- 
rately marked central area. The rays are long and symmetrically arranged, with sides that 
are straight or slightly convex. The rays have a slight taper and terminate in simple sharp 
points. 

Remarks.— Discoaster neorectus has simple, pointed terminations that distinguish it 
from Discoaster brouweri brouweri Tan, emended, which has rays bent like umbrella ribs, 
and D. brouweri rutellus Gartner, which has blade-like wedges at the end of each ray. Dis- 
coaster neorectus is distinguished from D. intercalaris by the narrower taper of the rays 
and by the lack of a significant central area. 

Occurrence.— \n nannofossil assemblages from the Pacific Ocean, Discoaster neorectus 
is common in only a limited stratigraphic horizon of the upper Miocene, upper Discoaster 
neohamatus Zone to lower Discoaster quinqueramus Zone. The unusually large size of this 
species makes it a convenient guide. Slightly less robust specimens than those of the Paci- 
fic, but equally large, are common in Core DSDP 3-10 from the Gulf of Mexico. 

Size.—2Q to 38 microns. 

Plate 4. Photomicrographs: 2,000 X. unless noted otherwise. 1-2. Discnaster intercalaris n. sp. (1) holotype 
USNM 176899, DSDP 36-12-5, 77-78 cm, (2) USNM 176900. 3-5. Discoaster loeblichii n. sp. (3) USNM 
176901, DSDP 83A-16-4, 64-65 cm, (4) holotype USNM 176902. DSDP 83A-15-6, 130-131 cm. (5) USNM 
176903, DSDP 83A-16-4, 64-65 cm. 6-7. Discoaster neorectus n. sp. (6) USNM 176904, DSDP 72.0-3-4, 63-64 
cm, magnification LOOO X, (7) holotype USNM 176905. 8-9. Fasciculithus clinatus n. sp. (8) holotype USNM 
176906, DSDP 47.2-9-5, 77-78 cm, (9) holotype, cross-polarized. 






1971 



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^: '* 


% 




-1 

'i 

1 








318 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Ho/ofvpe.-VSNM 176905 (PI. 4, fig. 7). 
Pararype.-VSNM 176904. 

Type locality— DSDP 72.0-3-4, 63-64 cm, western flank East Pacific Rise, equatorial 
Pacific Ocean. 

Genus Fasciculithus Bramlette and Sullivan. 1961 

Fasclculithus clinatus n. sp. 

Pi. 4, figs. 8-9 

Description.— This small simple species has a short conical form with a slightly 
rounded top that produces an almost triangular outline in side view. The base line is es- 
sentially straight in side view and is slightly longer than the upper sides, which are 
straight to slightly convex. In cross-polarized light, a single median extinction band bi- 
sects the triangular outline. 

Remarks.— Fasciculithus clinatus is distinguished from other species of Fasciculithus 
by its small size and almost triangular outline. The only comparable small form, F. tym- 
paniformis Hay and Mohler, is cylindric, with parallel instead of inclined sides. Fascicu- 
lithus ma^nus Bukry and Percival may have inclined sides for only half of its height and is 
much larger than F. clinatus. Also, F. clinatus lacks the pit-and-ridge ornamentation de- 
veloped in several other species, such as F. involutus Bramlette and Sullivan. 

Occurrence.— Fasciculithus clinatus is common in upper Paleocene sediment of the 
Shatsky Rise in the northwestern Pacific Ocean. 

^'/ze.— height. 4 to 6 microns. 

Holotype.-VSNM 176906 (PI. 4, figs. 8-9). 

Type locality.— DSDP 47.2-9-5, 77-78 cm, Shatsky Rise, northwestern Pacific Ocean. 

Genus Helicopontosphaera Hay and Mohler, 1967 
Helicopontosphaera heezenii n. sp. 

PI. 5, figs. 1-5 

Description.— This large species has a long bar, aligned with the long axis of the nan- 
nofossil. that dominates the central area. The length of the bar is 53 to 61 percent of the 
total nannofossil length. The bar is rounded at the ends, and although the sides are nor- 
mally smooth, some etched specimens show irregularities suggesting small perforations. 
In cross-polarized light, the central bar is brightest when aligned with a polarization di- 
rection. 

Remarks.— Helicopontosphaera heezenii is distinguished from similar forms such as 
Helicopontosphaera lophota (Bramlette and Sullivan) and H. papillata Bukry and Bram- 
lette by the greater length and the axial alignment of the central bar. It is distinguished 
from H. reticulata (Bramlette and Wilcoxon) by its non-rhomboid shape and non-diago- 
nal central bar. 

Occurrence.— Helicopontosphaera heezenii is common in the upper middle Eocene at 
DSDP 44 on Horizon Ridge in the northwestern Pacific Ocean, where it was first recog- 
nized. It also occurs in coeval sediment of Stetson 21, northwestern Atlantic Ocean. 

Plate 5. Photomicrographs: 2,UUU X. 1-5. Helicopontosphaera heezenii n. sp. ( 1 ) USNM 176907. DSDP 44.0-4- 
6, 145-150 cm. 45°, (2) holotype USNM 176908, 45°. (3) holotype. cross-polarized, 0°, (4) USNM 176909, 45°, 
(5) same as hgure 1. cross-polarized 90°. 6-9 Helicopontosphaera rhomba n. sp. (6) USNM 176910, DSDP 54.0-2- 
I, 67-68 cm, 45°, (7) holotype USNM 17691 1, DSDP 54.0-2-4, 81-82 cm, 45°, (8) holotype. cross-polarized. 90°. 
(9) same as figure 6. cross-polarized, 90°. 10-12. Sphenoliihus conicus n. sp. ( 10) holotype USNM 176912. DSDP 
80-5-2. 63-64 cm, 90°, (11) holotype, cross-polarized, 90°. ( 12) holotype, cross-polarized. 45°. 



1971 



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320 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

Size. — \3 to 18 microns. 
Holotvpe.-VSNM 176908 (PI. 5, figs. 2-3). 
Paratypes.-VSNM 176907, 176909. 

Tvpe localitv.—DSDP 44.0-4-6, 145-150 cm. Horizon Ridge, northwestern Pacific 
Ocean. 

Helicopontosphaera rhomba n. sp. 

PL 5, figs. 6-9 

Description.— This large species has a large elongate central opening that is bridged 
by a diagonal bar oriented at about 45° to the long axis of the nannofossil. In cross-polar- 
ized light, the diagonal bar is bright when the long axis of the nannofossil is aligned with 
a polarization direction, but it is dark at 45°. The short-axis extinction bands are broad 
and diffuse when the nannofossil is at 90°. The bar is not in optical continuity with the 
rim. 

Remarks.— Helicopontosphaera rhomba is distinguished from Helicopontosphaera loph- 
ota (Bramlette and Wilcoxon) by its more elongate shape, larger central opening, and 
more diffuse short-axis extinction bands. It is distinguished from H. intermedia (Martini) 
by its larger, non-sigmoid bar; from H. parallela (Bramlette and Wilcoxon) by its more 
open central area and diagonally aligned bar; and from H. bramlettei Mtiller ( = H. wilcox- 
onii Gartner) by its more elongate outline and diagonal (approx. 45°) bar. 

Occurrence.— Helicopontosphaera rhomba is presently known only from the Philip- 
pine Sea in lower middle Miocene deposits cored during DSDP Leg 6. 

Size. — \5 to 18 microns. 

Holotvpe.-\]S^U 17691 1 (PI. 5, figs. 7-8). 

ParatYpes.-\}^^U 176910. 

Type locality. -r>S\:>? 54.0-2.4, 81-82 cm, Philippine Sea. 

Genus Sphenolithus Deflandre, 1952 
Sphenolithus conicus n. sp. 

PI. 5, figs. 10-12 

Description.— This large species is characterized by its tall triangular outhne in side 
view. The several apical spines are partly coalesced to form the triangular to rounded 
triangular upper section of the nannofossil. In cross-polarized light, the base is divided 
into quadrants by the extinction bands when the long axis of the nannofossil is ahgned 
with a polarization direction. The height of the lower quadrants is equal to or slightly 
greater than the upper quadrants. The apical complex is bright when oriented at 45° to 
the polarization directions. 

Remarks.— Sphenolithus conicus could be mistakenly identified as a large Spheno- 
lithus heteromorphus Deflandre but is distinguished by the greater proportion of the fossil 
that is formed by the basal quadrants instead of by the apical complex. It is distinguished 
from S. moriformis (Bronnimann and Stradner) by its triangular instead of hemispheric 
outline. 

Occurrence.— Sphenolithus conicus occurs in lower lower Miocene sediment of the 
lower Triquetrorhahdulus carinatus Zone from the Pacific Ocean. 

Size.—l to 12 microns. 

//o/o/v/7e.-USNM 176912(P1. 5, figs. 10-12). 

Type locality.-U^D? 80-5-2, 63-65 cm, East Pacific Rise, eastern equatorial Pacific 
Ocean. 



1971 BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 321 

Sphenolithus obtusus n. sp. 

PI. 6, figs. 1-9 

Description.— This species has a short cycle of small basal spines and a large tapering 
apical spine constructed of two vertically matched halves. The apical spine halves are 
flush and terminate together. Seen in side view and cross-polarized light, the contact be- 
tween the two spine crystallites is planar, because (1) a black median line appears when 
the median plane of the spine is aligned to a polarization direction, (2) a solid black or 
white spine appears if a specimen is rolled so that the median plane is parallel to the mi- 
croscope stage and thus perpendicular to the polarization directions, and (3) oblique ori- 
entations produce an off-center black line. In bright field, with a single polarizer, the 
apical spine is at low relief when aligned to a polarization direction, and the basal cycle is 
at high relief When aligned perpendicular to a single polarization direction, the broad 
base of the apical spine shows a round outline. In cross-polarized light this contributes to 
the diagnostic obtuse angle made by the extinction line between the apical spine and the 
basal spine cycle. The basal cycle is short and simple. No side-oriented spines lie between 
the apical spine and the downward, proximally directed basal cycle. 

Remarks.— Sphenolithus obtusus is distinguished from S. furcatoUthoides Locker by 
the consistent obtuse angle formed between the apical spine and the extinction line be- 
tween the basal spine in cross-polarized light. Sphenolithus furcatoUthoides has a single 
straight extinction fine that is perpendicular to the nannofossil axis; it also has divergent 
halves of the apical spine. Sphenolithus obtusus is distinguished from S. distentus (Mar- 
tini) by the three-line extinction pattern of the basal spines, which are also longer than 
those of 5'. distentus. 

In its most typical orientation on prepared slides, S'. obtusus has the median plane of 
the apical spine perpendicular to the slide surface. In cross-polarized light at 15° to 25° 
one whole side of the nannofossil— the base and apical side— is dark. At 45°, the extinction 
line is missing from the apical spine: instead a light blue line is present that marks the 
trace of the median plane. 

Occurrence.— Sphenolithus obtusus is common in upper middle Eocene sediment from 
Horizon Ridge, northwestern Pacific Ocean. Sphenolithus furcatoUthoides occurs with S. 
obtusus only in the lower part of the range of 5'. obtusus. This distribution, together with 
the similarity in construction, suggest the derivation of 5'. obtusus from S. furcatoUthoides. 

Size.— 6 to 12 microns. 

Holotvpe.-VSNM 176913 (PI. 6, figs. 1-6). 

Paratypes.-USNM 176914-176915. 

Type locality.— DSDP 44.0-4-2, 145-150 cm, Horizon Ridge, northwestern Pacific 
Ocean. 

Sphenolithus spiniger n. sp. 

PL 6, figs. 10-12; PI. 7, figs. 1-2 

Description.— This small species is dominated by a basal ring of spines. In cross-polar- 
ized light, the lower basal quadrants are about twice as tall as the upper basal quadrants. 
The apical structure appears to be a single small spine that is bright at 45° and dark 
black, when oriented parallel with a polarization direction. When the nannofossil axis is 
oriented parallel with a polarization direction, the median extinction band is flared near 
the base of the specimen, giving the large lower quadrants a rounded appearance. At 45° 
to the polarization directions, the area occupied by the dark flare of 0° or 90° contains 
two bright spines that form an inverted "v'' and that are outlined by black extinction 



322 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



1971 BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 323 

bands. 

Remarks.— Sphenolithus spiniger is distinguished from other species of Sphenolithus 
by the unique optical pattern of the basal spines in cross-polarized light and also by the 
small size and vestigial apical structure. It is distinguished from S. dissimilis Bukry and 
Percival by the triangular outline, the smaller apical structure, and the smaller upper 
quadrants of the basal structure. 

Occurrence.— Sphenolithus spiniger is common in upper middle Eocene sediment of 
Horizon Ridge in the northwestern Pacific Ocean. 

^/ze.— width, 4 to 5 microns; height. 5 to 6 microns. 

//o/o/i/?e.-USNM 176916 (PI. 6, figs. 10-12). 

Paraiype.-XJ^^U 176917. 

Type locaUty.—D'bD? 44.0-4-6, 145-150 cm, Horizon Ridge, northwestern Pacific 
Ocean. 

Striatococcolithus n. gen. 

Description.— These circular and subcircular placoliths are composed of two simple 
shields connected at the center by a small tube. Each shield is composed of a single cycle 
of narrow essentially radial elements. In cross-polarized light either both the shields and 
the small central area are dark to faintly visible, or the shields are dark, but a tiny central 
area is bright. The lower shield is distinctly smaller than the upper shield. 

Type species.— Striatococcolithus pacificanus n. sp. 

Remarks.— Striatococcolithus is distinguished from other genera constructed of two 
shields and having small simple central areas by the consistent crystallographic alignment 
of its shield and central area crystallite elements that results in a typical dark appearance 
of the entire placolith in cross-polarized light. Of the most similar genera, Cyclococcoli- 
thina Wilcoxon is distinguished by the bright appearance of its smaller shield in cross- 
polarized light. Markalius Bramlette and Martini has strongly inchned and imbricated 
rim elements and a central area that is consistently bright in cross-polarized light. 

Striatococcolithus pacificanus n. sp. 

PI. 7, figs. 3-8 

Description.— This circular to subcircular placolith has two distinct shields, each com- 
posed of a single cycle of 40 to 60 narrow, radial crystallites. The diameter of the larger 
shield is 1.6 to 1.7 times that of the smaller shield. The central area is small, occupying 
only 15 percent or less of the diameter of the larger shield. In cross-polarized light both 
shields and the central area are typically dark or only faintly visible. A few specimens 
have a small, vestigial, elliptic, central area that is bright. 

Remarks.— Striatococcolithus pacificanus differs from other circular to subcircular 
placoliths by lacking birefringence in both shields and in the central area. The radial crys- 
talhtes appear as prominent bands extending from the margins to the centers of the 
shields. Specimens of S. pacificanus that have a small bright central area are distinguished 
from Markalius inversus (Deflandre) by their thin, radial, slightly imbricate shield con- 
struction. 

Plate 6. Photomicrographs; 2,000 X. 1-9. Sphenolithus obtusus n. sp. ( 1) holotype USNM 176913, DSDP 44.0- 
4-2, 145-150 cm, cross-polarized, 0°, (2) holotype, cross-polarized, 45°, (3) holotype, cross-polarized, 22°, (4) 
holotype 0°, (5) holotype, 45°, (6) holotype. 90°, (7) USNM 176914, 45°, (8) cross-polarized, 20°, (9) USNM 
176915, cross-polarized, 45°, median plane perpendicular to polarization directions. 10-12. Sphenolithus spin- 
iger n. sp. (10) holotype USNM 176916, DSDP 44.0-4-6, 145-150 cm, 90°, (11) holotype, cross-polarized, 45°, 
(12) holotype, cross-polarized, 0°. 



324 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 





^^^^^^^^^^^^^^L JI^^^^^^^^^^^^^^^^^Hl * 1 




9 






1971 BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 325 

Occurrence.— StriatococcoUthus pad ficanus occurs through lower Eocene sediment of 
the Shatsky Rise in the Pacific Ocean. 
Size.~\Q to 14 microns. 
Holotype.-\JS^M 176919 (PI. 7, figs. 4-5). 
Paratvpes.-XJS^M 176918, 176920-176921. 
Type locality.— DSDP 47.2-7-3, 82-83 cm, Shatsky Rise, northwestern Pacific Ocean. 

Genus Triquetrorhabdulus Martini, 1965 
Triquetrorhabdulus milowii n. sp. 

PI. 7, figs. 9-12 

Description.— This small species is constructed of three blades joined symmetrically at 
a common axis. Oriented in side view, the nannofossil outline, which is formed by two of 
the blades, is elliptic to rounded rhomboid. In this same orientation, the third blade is 
seen in edge view. Maximum relief above the mounting medium (n= 1.518) and max- 
imum birefringence occur at 45° to the polarization directions. In cross-polarized light, 
the typical color pattern ofyellow for the two blades in profile, red for the area next to the 
third blade (edge view), and blue for the third blade, is a measure of the various thick- 
nesses of the nannofossil at this orientation. Minimum relief and birefringence (dark) for 
the whole nannofossil is parallel with the polarization directions. Typically the width of 
the nannofossil is equal to one half or more of the length. 

Remarks. — Triquetrorhabdulus milowii is distinctly shorter than any other species of 
Triquetrorhabdulus. It is distinguished from T. inversus Bukry and Bramlette and T. ru- 
g<95z/5 Bramlette and Wilcoxon by the orientation of the optic axis of the three blades. It is 
distinguished from T. carinatus Martini, with which it shares the same optic-axis pattern, 
by a shorter more "inflated" profile. T. milowii is typically one half or two thirds as wide 
as long and blade margins tend to be curved, whereas T. carinatus is only one third or one 
fourth as wide as long. Younger specimens of T. milowii tend to be shorter and more ellip- 
tic in outline than older specimens, with one end slightly wider than the other. This nan- 
nofossil has been recorded as T. carinatus [short] in Deep Sea Drilling Project reports on 
the tropical Pacific Ocean. The stratigraphic utility of this species was suggested by Dean 
Milow (pers. comm., 1969). 

Occurrence. — Triquetrorhabdulus milowii is common to rare in lower Miocene sedi- 
ments of the Pacific Ocean and Cipero section of Trinidad. Early forms of T. milowii over- 
lap the upper range of T. carinatus in the Triquetrorhabdulus carinatus Zone, but T. 
milowii persists upward into the Sphenolithus belemnos Zone and possibly into the lower 
Helicopontosphaera ampliaperta Zone, which are above the range of T. carinatus. 

Size.— 6 to 12 microns. 

Holotvpe.-VS^M 176922 (PI. 7, figs. 9 and 12). 

Paran/7e.-USNM 176923. 

Type locality.— DSDP 74.0-4-4, 63-64 cm, western flank East Pacific Rise, equatorial 
Pacific Ocean. 



Plate 7. Photomicrographs: 2,000 X. 1-2. Sphenolithus spiniger n. sp. ( 1) USNM 176917. DSDP 44.0-4-6, 145- 
146 cm, cross-polarized, 45°, (2) cross-polarized. 0°. 3-8. StriatococcoUthus pacificanus n. sp. (3) USNM 
176918. DSDP 47.2-7-2, 100-101 cm. (4) holotype USNM 176919, DSDP 47.2-7-3, 82-83 cm, (5) holotvpe, cross- 
polarized, (6) USNM 176920, DSDP 47.2-7-3, 104-105 cm, cross-polarized, (7) USNM 176921. DSDP 47.2-7-3, 
82-83 cm, (8) cross-polarized. 9-12. Triquetrorhabdulus milowii n. sp. (9) holotype USNM 176922, DSDP 74.0- 
4-4, 63-64 cm, 45°, ( 10) USNM 176923, 45°, ( 1 1) cross-polarized, 45°, ( 12) holotype, cross-polarized, 45°. 



326 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



SAMPLE LOCALITIES 



DSDP3 (23°OrN., 77°43'W.) 
DSDP36 (40°59'N., I30°07'W.) 
DSDP44.0(19°19'N., I69°00'W.) 
DSDP47.0(32°27'N.. 157°43'E.) 
DSDP47.2(32°27'N., 157°43'E.) 
DSDP54.0(15°37'N.. 140°18'E.) 
DSDP55.0( 9°18'N.. 142°33'E.) 
DSDP57.2( 8°4rN.. 143°32'E.) 
DSDP63.0( 0°50'N., 147°53'E.) 
DSDP63T( 0°50'N., I47°53'E.) 
DSDP70.0( 6°20'N.. I40°22'W.) 
DSDP72.0( 0°26'N., 138°52'W.) 
DSDP74.0( 6°14'S., 136°06'W.) 
DSDP77B( 0°29'N.. 133°I4'W.) 
DSDP80 ( 0°58'S., 12I°33'W.) 
DSDP83A( 4°03'N., 95°44'W.) 
STETSON 21, (38°58'N., 72°28'W.) 
Sample provided by M. N. Bramlette. 



ACKNOWLEDGMENTS 

The majority of the samples examined in this study were provided by the National Science Foundation 
through the Deep Sea Drilling Project. 

I wish to thank M. N. Bramlette, Scripps Institution of Oceanography, R. G. Douglas, Case Western Re- 
serve University, A. D. Warren, Mobil Oil Corporation, and G. W. Moore, U.S. Geological Survey for helpful 
discussions on various aspects of this paper. Publication has been authorized by the Director of the U.S. Geolog- 
ical Survey. 

LITERATURE CITED 

Berger. W. H. 

1970. Biogenous deep-sea sediments; Fractionation by deep-sea circulation. Geol. Soc. America Bull. 81: 
1385-1402. 

Berggren, W. A. 

1971. Tertiary boundaries and correlations. ///, Funnell, B. M., and W. R. Riedel (eds.) The micro- 
paleontology of oceans. Cambridge University Press, p. 693-809. 

Bramlette, M.N. 

1970. Calcareous nannoplankton. U.S. Geol. Surv. Prof. Paper 640-A: 18. 

Bramlette, M. N., and E. Martini 

1964. The great change in calcareous nannoplankton fossils between the Maestrichtian and Dan- 
ian. Micropaleontology 10: 291-322. 

Bramlette, M. N.. and W. R. Riedel 

1954. Stratigraphic value of discoasters and some other micro fossils related to recent coccolithophores. J. 
Paleont. 28: 385-403. 

Bramlette, M. N., and J. A. Wilcoxon 

1967. Middle Tertiary calcareous nannoplankton of the Cipero section, Trinidad, W. 1. Tulane Studies 
Geol. 5:93-131. 

Bukry, D. 

1971. Coccolith stratigraphy Leg 7. Deep Sea Drilling Project. Deep Sea Drilling Proj. Initial Repts. 7: 
1513-1528. 

Coccolith stratigraphy Leg 16, Deep Sea DriUing Project. Deep Sea Drilling Proj. Initial Repts. 16, 
in press. 

Bukry, D., and M. N. Bramlette 

1970. Coccolith age determinations Leg 3, Deep Sea Drilling Project. Deep Sea Drilling Proj. Initial 
Repts. 3: 589-611. 

Chave, K. E., and E. Suess 

1967. Suspended minerals in seawater. New York Acad. Sci. Trans. 29: 991-1000. 



1971 BUKRY: CENOZOIC PACIFIC NANNOFOSSILS 327 

Douglas, R. G. 

1971. Cretaceous Foraminifera from the northwestern Pacific Ocean: Leg 6, Deep Sea Drilling Proj- 
ect. Deep Sea Drilling Proj. Initial Repts. 6; 1027-1053. 

Franke. W. W., and R. M. Brown, Jr. 

1971. Scale formation in Chrysophycean algae. III. Negatively stained scales of the coccolithophorid Hy- 
menomonas. Archiv Mikrobiologie 77: 12-19. 

Gartner, S., Jr. 

1969. Correlation of Neogene planktonic foraminifer and calcareous nannofossil zones. Gulf Coast As- 
soc. Geol. Socs. Trans. 19: 585-599. 

1971. Calcareous nannofossils from the JOIDES Blake Plateau cores, and revision of Paleogene nannofos- 
sil zonation. Tulane Studies Geol. Paleont. 8: 101-121. 

Hay, W. W., H. P. Mohler, P. H. Roth, R. R. Schmidt, and J. E. Boudreaux 

1967. Calcareous nannoplankton zonation of the Cenozoic of the Gulf Coast and Caribbean-Antillean 
area, and transoceanic correlation. Gulf Coast Assoc. Geol. Socs. Trans. 17: 428-480. 

Hulburt, E. M. 

1962. Phytoplankton in the southwestern Sargasso Sea and north equatorial current, February 1961. Lim- 
noi. Oceanogr. 7: 307-315. 

Hulburt, E. M.. and J. Rodman 

1963. Distribution of phytoplankton species with respect to sahnity between the coast of southern New 
England and Bermuda. Limnol. Oceanogr. 8: 263-269. 

Lawrence, D. R. 

1971. The nature and structure of paleoecology. J. Paleont. 45: 593-607. 

Martini, E.. and M. N. Bramlelte 

1963. Calcareous nannoplankton from the experimental Mohole drilling. J. Paleont. 37: 845-856. 

Martini, E., and T. R. Worsley 

1971. Tertiary calcareous nannoplankton from the western equatorial Pacific. Deep Sea Drilling Proj. In- 
itial Repts. 7: 1471-1507. 

Milow, E. D. 

1970. Tentative nannofossil zones and subzones and their radiometric age, northeast Pacific. Deep Sea 
Drilling Proj. Initial Repts. 5: 8-10. 

Peterson, M. N. A. 

1966. Calcite: rates of dissolution in a vertical profile in the central Pacific. Science 154: 1542. 

Pytkowicz, R. M. 

1969. Chemical solution of calcium carbonate in seawater. Amer. Zool. 9: 673-679. 

Roth. P. H. 

1970. Oligocene calcareous nannoplankton biostratigraphy. Eclogae Geol. Helvetiae 63: 799-881. 

Smith, S. v., J. A. Dygas, and K. E. Chave 

1968. Distribution of calcium carbonate in pelagic sediments. Mar. Geol. 6: 391-400. 

Tappan, H. 

1971. Microplankton, ecological succession and evolution. North Amer. Paleont. Convention Proc. H: 
1058-1103. 

Wilcoxon, J. A. 

1970. Cvclococcolithina Wilcoxon nom. now (nom. subst. pro Cyclococcolithus Kampter, 1954). Tulane 
Studies Geol. Paleont. 8: 82-83. 



U.S. Geological Survey, Scripps Institution of Oceanography, LaJolla, California 92037. 




MUS. COIVIP. ZUUi- 
LIBRARY 

FEB 1 8 197^ 

HARVARD 
UNIVERSITY 



AN UPPER PLEISTOCENE MARINE FAUNA 
FROM MISSION BAY, 
SAN DIEGO, CALIFORNIA 



J. PHILIP KERN, TOM E. STUMP, 
AND ROBERT J. DOWLEN 



TRANSACTIONS 

OF THE SAN DIEGO 
SOCIETY OF 
NATURAL HISTORY 

VOL. 16, NO. 15 29 DECEMBER 1971 



AN UPPER PLEISTOCENE MARINE FAUNA FROM MISSION BAY, 
SAN DIEGO, CALIFORNIA 

J. PHILIP KERN. TOM E. STUMP, AND ROBERT J. DOWLEN 



ABSTRACT.— Sixty-nine invertebrate species and one chordate have been collected from the upper Pleisto- 
cene Bay Point Formation on the northeast shore of Mission Bay in San Diego, California. This protected- 
bay assemblage lived in water depths of 1 to 2 m. Rocky-shore species at the base of the section were re- 
placed bv mudflat species as the initially deposited gravel and boulders were covered by sand and mud. The 
fauna includes three or four southern extrahmital species; their paleoclimatic implications are not clear. 

INTRODUCTION 

The upper Pleistocene Bay Point Formation crops out in a number of small, isolated 
exposures on the lowest well-developed, emergent marine terrace (Nestor terrace of Ellis, 
1919: pi. 6; La Jolla terrace of Hanna, 1926: 194-195) and at corresponding elevations in 
coastal embayments from Oceanside, California to northern Baja California. Marine fos- 
sil assemblages are preserved in several outcrops of this formation in the area of Mission 
Bay in northern San Diego (Fig. 1). Exposed-coast faunas occur at Pacific Beach (Valen- 
tine, 1961: 359-361. tables 19. 20) and Sunset Chfts (Valentine and Meade. 1961: 11-13, 
table 2). Fossils at Crown Point, the type locality of the Bay Point Formation, hved on or 
near a barrier beach that protected the Pleistocene Mission Bay to the east from strong 
wave action (Valentine. 1959: 687); the present-day barrier is a mile farther west. Two 
small, sheltered-water faunas were reported by Stephens (1929: 253. 255). one from the 
northeast shore of Mission Bay (the railroad cut locality) and one from the south shore. 
Another sheltered-water fauna was described by Emerson and Chace (1959) from Teco- 
lote Creek on the east shore. All the above localities are shown in Figure 1. 

The sheltered-water fauna reported by Stephens (1929: 253) from the northeast 
shore of Mission Bay (railroad cut locality) has been referred to subsequently by Valen- 
tine (1959: 687: 1961: 359) and by Emerson and Chace (1959: 340). but this fauna has 
never been adequately studied. The locality is near the base of the steep northeastern 
slope of the present embayment, and the sediments here clearly were deposited close to 
the eastern shore of the Pleistocene Mission Bay. The purpose of this paper is to describe 
this fauna and discuss its paleoenvironmental implications. 

San Diego State College locahty 2276 (Figs. 1-3) is 230,600 ft. north and 1.704,800 ft. 
east in zone 6 of the California coordinate system (U.S. Geol. Surv. 7.5 minute La Jolla, 
California quad.. 1967 ed.). It is in a low cut on the east side of the tracks of the Santa Fe 
Railroad between Morena Boulevard and Interstate 5. Fossils should not be collected 
from this locahty without the permission of officials of the Santa Fe Railroad. 

STRATIGRAPHY 

At this locahty the Bay Point Formation lies unconformably on Pliocene rocks of the 
San Diego Formation. From the lower part of the exposed Bay Point Formation we col- 
lected reworked Pliocene fossils including Astrangia sp.. Opalia varicostata Stearns, and 
two unidentified species of the gastropod families Turridae and Thaididae. 

The exposed Pleistocene section is approximately 2 m thick and is fossiliferous for a 
lateral distance of about 30 m (Figs. 2 and 3). At the base of the section are 60 to 70 cm of 
poorly sorted conglomerate containing sub-rounded boulders up to 60 cm in diameter. 
The matrix of the conglomerate is poorly consolidated, poorly sorted, predominantly 
coarse-grained, brown sand. The fossiliferous upper part of this bed is finer-grained, and 

SAN DIEGO see. NAT. HIST.. TRANS. 16(15): 329-338. 29 DECEMBER 1971 



330 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 




Figure \. Map of the Mission Bay area showing the location of San Diego State College locality 2276 (Stephens' 
railroad cut locality) and other Bay Point Formation fossil localities at Pacific Beach (1), Crown Point (2), Teco- 
lote Creek (3), south Mission Bay (4), and Sunset Cliffs (5). Inferred late Pleistocene land areas are shaded. The 
extension of the barrier beach south of Crown Point is based on the presence of sheltered-bay fossil faunas be- 
hind the barrier and the typical development of such barriers today. Probably the barrier was alternately open 
and closed. 



1971 



KERN. STUMP AND DOWLEN: PLEISTOCENE MARINE FAUNA 



331 



the conglomerate grades rather abruptly upward into somewhat better sorted, poorly con- 
solidated, fine-grained, brown sand. There is a slight upward decrease in grain size 
through the upper part of the section. Grain-size analyses for the beds described below 
are shown in Table 1. 



Table 1. Sediment grain-size analyses made by the dry sieve method described by Folk (1968: 
Ranges are given because two or more samples from each bed were analyzed. 



34-36). 



coarser than sand 



coarse sand 
-l</>to 1</) 



medium sand 
l4>to 24> 



fine sand 
2(|)to4</) 



silt and clay 
>4</) 



bed 3 


1-4% 


5-12% 


12-22% 


53-70% 


9-12% 


bed 2 


2-6 


4-7 


22-31 


54-60 


4-12 


bed 1 


30-32 


14-16 


21-22 


24-31 


4-6 


conglomerate 


70 


8 


9 


10 


3 



Fossils are distributed irregularly throughout the section above the lower part of the 
conglomerate. Collections were made from three rather arbitrarily defined stratigraphic 
intervals in order to evaluate temporal changes in the fauna. Bed 1 is a highly fossiliferous 
stratum in the upper 15 to 30 cm of the conglomerate (Fig. 3). Bed 2 is a poorly defined 
fossiliferous interval tYom 30 to 45 cm thick directly overlying bed 1. Bed 3 is an irregular 
stratum 30 cm thick and 15 cm above the top of bed 2. 



rf^^m^^ ^. 



if^S 





Figure 2. San Diego State College locality 2276 viewed from the southwest. The tracks of the Santa Fe Railroad 
are in the foreground, and the houses in the background are east of Morena Boulevard. Exposure A is the exca- 
vation in the bank directly below the street sign near the left edge of the view; exposure B is the smaller excava- 
tion at the right edge of the view. The lower parts of both excavations were filled in after the collections were 
made and before this photograph was taken. Fossils that have weathered out on the bank are visible between the 
two exposures. 



332 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL. 16 

METHODS AND FAUNAL LIST 

Each bed was sampled at two exposures, designated A (at the northern end of the 
outcrop) and B ( 10 m to the south of A; Fig. 2). We collected 18 to 22 kg of sediment and 
fossils in each sample except the one from 2A, which was twice that size. Each sample was 
washed through a 10-mesh (2 mm) screen, and all identifiable fossil specimens were 
picked from the material retained in the screen. Sediment passing through the screen was 
examined for microfossils but none were found. 

Sixty-seven species of mollusks, one chordate species, and borings of unidentified 
species of Polydora, an annelid, and Cliona, a sponge, have been identified. The distribu- 
tion and abundance in the three beds of those species collected during this study are 
shown in Table 2. Also indicated in Table 2 are species present in earlier San Diego State 
College collections from this locality and in the collections of the San Diego Natural His- 
tory Museum. The latter include at least part of Stephens' ( 1929: 253) collection from this 
locality, though we have not been able to find two of the species he listed, Macoma cal- 
carea and Phacoides californica. His Macoma probably is Psammotreta viridotincta, which 
is common in his collection, but that collection now contains no specimens likely to be 
confused with Phacoides [ = Lucina] californica. 

AGE OF THE FAUNA 

Odostomia diegensis is the only species in this fauna not known to be living. Addicott 
and Emerson (1959: 24) suggested that all essentially modern fossil faunas preserved at 
the lowest emergent terrace level in southern California probably are correlative with the 
regional type upper Pleistocene Palos Verdes Sand at San Pedro. The Bay Point Forma- 
tion, which is deposited in part on this terrace, probably is correlative, then, with upper 
Pleistocene deposits at San Pedro, Cayucos, and San Nicolas Island that have been dated 
radiometrically at between 95,000 ± 15,000 and 140,000 ± 30,000 years (see discussion 
in Kern, 1971: 812). These faunas may have lived during Sangamon interglacial time or 
during an earlier interglacial episode. 

ENVIRONMENT OF DEPOSITION 

Environmental interpretations are based on distribution data for living species from 
Berry (1922), Oldroyd (1927), Grant and Gale (1931), Burch (1944-1946), Hertlein and 
Strong (1955), Morris (1966), Ricketts and Calvin (1968), McLean (1969), and Keen 
(1971). The fossil fauna is characteristic of the protected-bay environment, consistent with 
the probable paleogeographic setting of the locality (Fig. 1). However, the inferred coast- 
line suggests that this shore was exposed to over a mile of open water behind the barrier 
beach, and several moUuscan species also suggest that the fauna lived in a somewhat ex- 
posed part of the bay. Littorina scutulata, a common species at this locality, is most abun- 
dant today in the less protected parts of bays (Ricketts and Calvin, 1968: 237). Lottia 
gigantea and Mopalia ciliata, rare species in this fauna, are characteristic of a protected 
outer coast (Ricketts and Calvin, 1968: 26, 138), but they may occur rarely in the rela- 
tively exposed parts of bays. 

ORIGIN OF FAUNAL ASSEMBLAGE 

The composition of the fossil fauna and the abundance of worn and broken shells 
that are concentrated in irregular beds, lenses, and pockets reflect local reworking of sedi- 
ment and mixing of shells from slightly different depth zones. Littorina planaxis, L. scutu- 
lata. Assiminea translucens, Melampus olivaceus, and Heterodonax himaculatus live at or 



1971 



KERN. STUMP AND DOWLEN: PLEISTOCENE MARINE FAUNA 



333 



Table 2. Distribution and abundance of fossil species in beds 1. 2, and 3 in two exposures at San Diego State College locality 2276. Numbers 
are pairs of bivalves and individual specimens of other fossils. The first two columns indicate species present m other collections at San Diego 
State College ISDSC) and at the San Diego Natural History Museum (SDNHM). Data on abundance and on distribution within the outcrop are 
not available for these collections. 



Collections 



Species 



SDNHM SDSC lA IB 



2A 



2B 3A 3B 



Porifera 

Cliona sp. 

Annelida 

Polydora sp. 

Polyplacophora 

Mopalia ciliata (Sowerby, 1840) 

Gastropoda 

Acnwea insessa (Hinds, 1843) 
Acmaea instabilis (Gould, 1846) 
Acnwea scabra (Gould, 1846) 
Lottia gigantea (Sowerby, 1833) 
Lucapinella callomarginata (Dall, 1871) 
Tegula gallina (Forbes, 1850) 
Liotia fenestrata (Carpenter, 1864) 
Epitonium indianorum (Carpenter, 1864) 
Littorina planaxis (Philippi, 1847) 
Littorim scutulata (Gould, 1849) 
Lacuna sp. 

Assiminea translucens (Carpenter, 1864) 
?Solariorbis sp. 

Alabina tenuisculpta (Carpenter, 1864) 
Cerithiopsis carpenteri (Baitsch, 1911) 
Cerithidea californica (Haldeman, 1840) 
Hipponix lumens (Carpenter, 1864) 
Creptdula perforans (Valenciennes, 1846) 
Crepidula sp. 

Crepipatella lingulala (Gould, 1846) 
Eupleura muriciformts (Broderip, 1833) 
Morula lugubris (C. B. Adams, 185 2) 
Anachis coronata (Sowerby, 1832) 
Mttretla carinata (Hmds, 1844) 
Nassarius tegula (Reeve, 1853) 
Olivella biplicata (Sowerby, 1825) 
Conus californlcus (Hinds, 1844) 
Odostomia diegensis (Dall & Bartsch, 1903) 
Peristichia pedroana (Dall & Bartsch, 1909) 
Pyramidella adamsi iCMpentei. 1864) 
Turbonilla sp. 

Acteoclna culcitella (Gould, 1853) 
Acteon punctocoelata (Carpenter, 1864) 
Melampus olivaceus (Carpenter, 1856) 
Pedipes liratus (Binney. 1860) 

Bivalvia 

Nucula aff . A', exigua (Sowerby, 1833) 
Anadara multicostata (Sowerby, 1833) 
Septlfer bifurcatus (Conrad, 1837) 
Ostrea lurida (Carpenter, 1864) 
Argopecten circularis (Sowerby, 1835) 
Leptopecten latiauratus (Conrad, 1837) 
Lima sp. 

Anomia peruviana (Orbigny, 1846) 
Crassinella branneri (Arnold, 1903) 
Lucina nuttallii (Conrad, 1837) 
Here excavata (Carpenter, 1857) 
Diplodonta sericata (Reeve, 1850) 
Laevicardium substriatum (Conrad, 1837) 
Pilar newcombianus (Gabb, 1865) 
Chione californiensis (Brodenp, 1835) 
Chione fluctifraga (Sowerby, 1853) 
Chione gnidia (Broderip & Sowerby, 1829) 
Callithaca staminea (Conrad, 1837) 
Mactra californica (Conrad, 1837) 
Spisula cf. 5. hemphilli (Dall, 1894) 
Tellina bodegensis (Hinds, 1844) 
Tellina meropsis (DaU, 1900) 
Macoma nasuta (Coruad, 1837) 
Psammotreta viridotincta (Carpenter, 1856) 
Cumingia californica (Conrad, 1837) 
Donax californlcus (Coniid, 1837) 
Heterodonax bimaculatus (Linnaeus, 1758) 
Tagelus calif ornianus {Qontzi, 1837) 
Cryptomya californica (Conrad, 1837) 
Corbula luteola (Carpenter, 1864) 
Corbula sp. 

Chorda ta 

Myliobatis sp. 



X 
X 



X 
X 



X 
X 



X 
X 
X 



X 
X 
X 
X 



X 
X 

X 
X 



X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 



X 
X 
X 

X 
X 

X 
X 

X 
X 
X 
X 
X 
X 



X 
X 
X 
X 
X 

X 
X 

X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 

X 
X 
X 
X 
X 



10 



31 



48 



12 
35 

1 



1 

27 
12 

61 



13 



26 



25 



25 



70 



66 





2 










3 








24 

1 


428 


112 


25 


28 




1 
4 


13 
5 




1 




3 


2 








10 

2 


10 
10 


5 


9 

2 


17 
15 
2 


1 

5 
3 
4 


2 

6 
10 

2 


1 

1 


1 

1 

10 

1 


1 
26 


1 

6 

133 


7 
7 


2 


3 


5 


190 


415 


75 


42 


38 
35 


2 

89 

9 

15 
1 


70 
2 
3 
43 


3 
9 


2 
13 

15 


2 
8 


1 
42 


110 


22 


18 




25 


28 




1 

1 


1 


110 


45 
2 
2 


65 

1 


18 
1 



334 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



near high tide level where few other marine species live, and Cehthidea californica is most 
common on middle intertidal mud and sand flats where few other species are abundant. 
Yet at this locality these species are part of a rather diverse assemblage of invertebrates, 
most of which extend from the lower part of the intertidal zone into deeper water. Be- 
cause of the relative turbulence of the intertidal zone, even in sheltered environments, 
such mixing of species from diflerent intertidal levels is not unexpected. 




■y 






Figure 3. Exposure A at San Diego State 
College locality 2276. The lower part of 
the excavation has been covered since the 
collections were made, and the basal con- 
glomerate and bed I are no longer ex- 
posed. The abundant fossils in the lower 
part of the exposure are in bed 2, and the 
small lens of fossils higher in the exposure 
is in bed 3. The irregularity and dis- 
continuity of these beds is evident. The 
pencil is 13 cm long. 



However, in spite of this evidence for turbulent conditions and local reworking of 
sediment, there apparently was no large-scale sediment transport. With the few excep- 
tions described below all the species in this fauna live in the intertidal zone of sheltered 
bays; thus there was no mixing of shells from widely different environments. In situ pres- 
ervation of the majority of species is suggested by the presence of approximately equal 
numbers of right and left valves of several bivalve species and by high percentages of ar- 
ticulated specimens of Lucina nuttalUi, Diplodonta sehcata, Chione californiensis, Psam- 
motreta viridotincta, and Tagelus californianiis. The deeply burrowing T. californianus 
commonly is preserved in life orientation in these beds. 

WATER DEPTH 

This fauna clearly lived in sediments deposited in or very near the intertidal zone. 
The shoreline angle of the Nestor terrace in this area is not more than 2 or 3 m higher 



1971 KERN, STUMP AND DOWLEN: PLEISTOCENE MARINE FAUNA 335 

than the fossil-bearing beds. Littorina scutulata, Cerithidea californica, Melampus oli- 
vaceus, Pedipes liratus, and Septifer bifurcatus are relatively abundant and they are re- 
stricted today to the intertidal zone, as are the less abundant Lottia gigantea, Lucapinella 
callomarginata, Littorina planaxis, Assiminea translucens, and Heterodonax bimaculatus. 
All but four of the other species range from the intertidal zone into deeper water. 

One of the four exceptions, Crassinella branneri is common in this fauna, and the 
genus has a reported depth range of 2 to 40 m (Keen, 1963: 105). Psammotreta virido- 
tincta, also common, occurs today "mostly offshore in depths to 14 fathoms" (Keen. 1971: 
231). However, the depth significance of this species is not clear because its present-day 
minimum depth is not known, and the change in its geographic range since late Pleisto- 
cene time (Table 3) suggests that its environmental tolerance limits may have changed. 
The collections also include four specimens each of Nucula aff. N. exigua and Pitar new- 
combianus. The former is known to live today in depths of 1 1 to about 2000 m (Keen, 
1971: 26) and the latter in depths of 9 m or more (McLean, 1969: 78). Though these 
depth ranges are inconsistent with those described above, the few specimens of these two 
species do not warrant substantial modification of the suggested depth interpretation, es- 
pecially in light of the questionable identity of the Nucula. However, the presence of these 
four apparently subtidal species in the fauna suggests that deposition may have occurred, 
at least in part, slightly below the intertidal zone. 

Bed 3 contains fewer species than beds 1 and 2, and most of the abundant species in 
bed 3, including Littorina scutulata, Cerithidea californica, Nassarius tegula, Melampus 
oUvaceus, Chione fluctifraga, and Tagelus californianus, today are restricted to or are most 
abundant in the intertidal zone. The other common species in bed 3. Diplodonta sericata, 
Protothaca staminea, and Tellina meropsis, are more abundant in bed 2, and these species 
are not restricted to or most abundant in the intertidal zone today. The four possibly sub- 
tidal species are uncommon in bed 3. Thus bed 3 apparently was deposited in the lower 
part of the intertidal zone, perhaps 1 m below mean sea level, and bed 1 was deposited in 
water perhaps 1 m deeper. Probably sea level was stable throughout the period of depo- 
sition, and the change in water depth reflects the thickness of sediments, about 1 m, de- 
posited from bed 1 through bed 3. The base of the outcrop is approximately 14 m above 
present mean sea level, so sea level when these sediments were deposited probably was 
about 16 m higher than it is today. The shoreline angle of the Nestor terrace in this area is 
within 30 m to the east and no more than 2 or 3 m higher than locality 2276, suggesting 
that at this level the sea was close to its maximum extent on the terrace. The approximate 
position of the coastline at that sea level is shown in Figure 1. 

The terrace deposits at Tecolote Creek (Fig. 1) are at a present elevation of 6 to 8 m 
at the base of the section and 14 to 16 m at the top. The fauna (Emerson and Chace, 1959: 
table 1) includes nearly all the intertidal species present at locality 2276, though their dis- 
tribution within the section is now known. Possibly the lowest beds were deposited some- 
what offshore in depths of 8 to 10 m and the highest beds, at about the same elevation as 
the beds at locality 2276, were deposited in or near the intertidal zone after this part of 
the basin had filled with sediments. Alternatively, sea level may have been rising during 
deposition of these sediments. 

Valentine (1959: 685, 687) suggested that maximum sea level during cutting of the 
Nestor terrace at Crown Point, Pacific Beach, and Sunset Cliffs (Fig. 1) was between 60 
and 70 feet (18 and 20 m) above present sea level and that the shallow-water assemblage 
at Crown Point, at a present elevation of 5 m at the bottom of the section and 9 m at the 
top, probably lived when the sea was well below its maximum extent on the terrace. This 
apparent difference in the sea levels under which these two faunas lived suggests that they 



336 



SAN DIEGO SOCIETY OF NATURAL HISTORY 



VOL. 16 



may not have been contemporaneous. 

SUBSTRATE 

Stratigraphic faunal changes also reflect a temporal change in the substrate. Tegula 
gallina, Littorina scutulalcL Septifer hifurcatus, Ostrea hirida, and Anomia peruviana live 
only or chiefly on hard substrates, and all are very abundant in bed 1 and are either rare 
or absent in beds 2 and 3. On the other hand, the characteristic mudflat species Tagelus 
californianus, Cerithidea californica, and Melampus olivaceus are rare in bed 1 and in- 
creasingly abundant in beds 2 and 3. Thus the stratigraphic change in faunal composition 
reflects both the decrease in water depth and the change from a coarse gravel and boulder 
substrate to mud. 

CLIMATE 

Species whose present-day geographic ranges end near or do not include San Diego 
are listed in Table 3 with their ranges. Six species do not live today south of the San 
Diego-Ensenada region, and a seventh lives only as far south as Bahia San Quintin. The 
questionably identified Spisula hemphilli also lives only as far south as Ensenada. Seven 
species live only as far north as the San Diego-Los Angeles region. The overlapping pres- 
ent-day ranges of these 14 species suggest that the late Pleistocene shallow-water marine 
climate in which they lived was similar to that at the same latitude today. 

However, the assemblage also contains several southern extralimital species, species 
that do not live today as far north as San Diego (Table 3). Anachis coronata, Psammotreta 
vihdotincta, and Chione gnidia live only as far north as Laguna Scammon or Lsla de 
Cedros (28° north latitude). Eupleura muriciformis also is reported to live today only as 
far north as lsla de Cedros, though Hertlein and Strong (1955: 258) included in its synon- 
ymy Ranella triquefra Reeve, 1844 from San Diego. Both Eupleura muriciformis and 

Table 3. Species with geographic ranges that end near or do not include the San Diego area. 



Species 



Geographic Range 



Acniaea instabilis 
Hipponix tumens 
Mopalia ciliata 
Epitonium indianorum 
Assiminea translucens 
Callithaca staminea 
Spisula cf. S. hemphilli 
Cerithiopsis carpenteri 

Alabina tenuisculpta 
Nucula aff. A^. exigua 
Atwdara cf. /I. multicostata 
Morula lugubris 
Pedipes liratus 
Crassinella branneri 
Eupleura muriciformis 

Anachis coronata 

Chione gnidia 
Psammotreta viridotincta 



Alaska to San Diego (Morris, 1959: 57) 

Crescent City to San Diego (Oldroyd, 1927,2(3): 113-114) 

Alaska to Bahia Todos Santos (Berry, 1922: 449-451) 

Alaska to Bahia Todos Santos (Oldroyd, 1927, 2 (2): 58) 

Vancouver to Punta Banda (McLean, 1969: 28) 

Alaska to Bahia San Quintin (Grant and Gale, 1931: 329) 

Santa Barbara to Ensenada (McLean, 1969: 82) 

San Pedro to South Coronado Island (Oldroyd, 1927, 2 (2): 

253) 
San Pedro to Magdalena Bay (Oldroyd, 1927, 2 (3): 14) 
Los Angeles to Ecuador (Burch, 1944-1946, no. 33: 7) 
Newport Bay to Galapagos Islands (Keen, 1971: 48) 
San Diego to Panama (Keen, 1971: 554) 
San Diego to Golfo de California (Oldroyd, 1927, 2(1): 54) 
San Diego to Panama (Oldroyd, 1927, 1: 110) 
(San Diego ?) lsla de Cedros to Lobitos, Peru (Hertlein and 

Strong, 1955: 258) 
Laguna Scammon to Ecuador (San Diego Natural History 

Museum Coll.) 
lsla de Cedros to Peru (Keen, 1971: 188) 
Laguna Scammon to Costa Rica (San Diego Natural History 

Museum Coll.) 



1971 KERN, STUMP AND DOWLEN; PLEISTOCENE MARINE FAUNA 337 

Chione gnidia are rare in this assemblage, but the other two species are rather abundant. 
Two additional uncommon species, Crassinella branneri and Nucula cf. A', exigua, have 
been regarded in some studies as southern extralimital species, though there are conflict- 
ing records on their geographic ranges; both species have been reported in the San Diego 
area. Thus there apparently are three or four species in this fauna that do not live today 
in the San Diego region or in the area of overlap of the present-day geographic ranges of 
all the other species in the assemblage. 

The paleoclimatic significance of extralimital species has been discussed by Emerson 
(1956: 326-327). Valentine (1955: 465-468; 1961: 393-400), Kern (1971: 819-820; in 
press), and others. Southern extralimital species commonly have been interpreted as in- 
dicating that shallow-water marine climates have been substantially warmer in the past 
than today, at least locally. However, the presence in this fauna of seven or eight mollus- 
can species that do not live today south of the San Diego region suggests that the late 
Pleistocene marine climate in this area was not as warm as the climate at Laguna Scam- 
mon and Isla de Cedros today. The geographic ranges of these and the extralimital spe- 
cies do not overlap today, and paleoclimatic interpretations based on assumed thermal 
limitations of their ranges must involve more complex changes than simple warming or 
cooling. It must also be recognized that some of these species may have changed physio- 
logically and ecologically since late Pleistocene time, and some of them may be limited 
geographically by factors other than water temperature (see discussion in Kern, in press). 

ACKNOWLEDGEMENTS 

The fossils on which this study are based were collected and prepared by members of a graduate class in 
paleoecology at San Diego State College. In addition to the authors this class included William Cunningham, 
Dennis Dowd, Rogers Hardy III, and Michael Hart. Sediment analyses were made by Dowd and Hardy. We 
also are indebted to Willard Libby, Geological Survey of Western Australia, for reviewing the manuscript, and 
to Arnold Ross and George Radwin, San Diego Natural History Museum, who granted access to the museum's 
fossil and Recent invertebrate collections. 

LITERATURE CITED 

Addicott, W. O., and W. K. Emerson 

1959. Late Pleistocene mvertebrates from Punta Cabras, Baja California, Mexico. Amer. Mus. Novitates 
1925; 1-33. 
Berry, S. S. 

1922. Fossil chitons of western North America. California Acad. Sci., Proc. (ser. 4) 11: 399-526. 
Burch, J. Q. [ed.] 

1944-1946. Distributional list of the west American marine Mollusca from San Diego, California, to the Po- 
lar Sea. Conch. Club S. California, Minutes. 
Ellis, A. J. 

1919. Physiography, p. 20-50. In A. J. Ellis and C. H. Lee, Geology and ground waters of the western part 
of San Diego County, California. U.S. Geol. Surv., Water Supply Paper 446. 
Emerson, W. K. 

1956. Pleistocene invertebrates from Punta China, Baja California, Mexico. Amer. Mus. Nat. Hist , Bull. 
Ill: 313-342. 
Emerson, W. K., and E. P. Chace 

1959. Pleistocene mollusks from Tecolote Creek, San Diego, California. San Diego Soc. Nat. Hist Trans. 
12: 335-346. 
Folk, R. L. 

1968. Petrology of sedimentary rocks. Hemphill's, Austin, Texas. 170 p. 
Grant, U. S., IV, and H. R. Gale 

1931. Catalogue of the marine Pliocene and Pleistocene Mollusca of California and adjacent regions. San 
Diego Soc. Nat. Hist., Mem. 1. 1036 p. 
Hanna, M. A. 

1926. Geology of the La Jolla quadrangle, California. Univ. Calif Pub. Geol. Sci. 16: 187-246. 



338 SAN DIEGO SOCIETY OF NATURAL HISTORY VOL.16 

Hertlein. L. G., and A. M. Strong 

1955. Marine mollusks collected during the "Askoy" expedition to Panama, Colombia, and Ecuador in 
1941. Amer. Mus. Nat. Hi.st.. Bull. 107: 159-318. 

Keen, A. M. 

1963. Marine molluscan genera of western North America. Stanford Univ. Press, Stanford, California. 126 

P- 
Keen, A. M. 

1971. Sea shells of tropical west America. Second Edition, Stanford Univ. Press, Stanford, California. 1064 

P- 
Kern, J. P. 

1971. Paleoenvironmental analysis of a late Pleistocene estuary in southern California. J. Paleont. 45: 810- 

823. 
Kern, J. P. 

Early Pliocene marine climate and environment of the eastern Ventura basin, southern California. 

Univ. Calif Pub. Geol. Sci., in press. 
VlcLean. J. H. 

1969. Marine shells of southern California. Los Angeles Co. Mus. Nat. Hist., Sci. Ser. 24, Zool. 11. 104 p. 

Morris. P. A. 

1966. A field guide to the shells of the Pacific coast and Hawaii. Houghton Mifflin, Boston. 297 p. 
Oldroyd, I. S. 

1927. The marine shells of the west coast of North America. Stanford Univ. Pub. Geol. Sci. 1, 2 (parts 1-3). 

Ricketts, E. P., and J. Calvin 

1968. Between Pacific tides. Fourth Edition, Stanford Univ. Press, Stanford. California. 614 p. 
Stephens, F. 

1929. Notes on the marine Pleistocene deposits of San Diego County, California. San Diego See. Nat. 
Hist., Trans. 5: 247-255. 
Valentine. J. W. 

1955. Upwelling and thermally anomalous Pacific coast Pleistocene molluscan faunas. Amer. J. Sci. 253: 
462-474. 
Valentine, J. W. 

1959. Pleistocene molluscan notes, I, The Bay Point Formation at its type locality. J. Paleont. 33: 685-688. 
Valentine, J. W. 

1960. Habitats and sources of Pleistocene mollusks at Torrey Pines Park, California. Ecology 41: 161-165. 
Valentine, J. W. 

1961. Paleoecologic molluscan geography of the Californian Pleistocene. Univ. California Publ. Geol. Sci. 
34: 309-442. 

Valentine, J. W., and R. F. Meade 

196 1. Californian Pleistocene paleotemperatures. Univ. California Publ. Geol. Sci. 40: 1-46, 



Department of Geology, San Diego State College, San Diego, California 92115 



7 9Ub u92 



Date Due 



-^m^MM^r 



ACME 

BOOKBINOiNG CO.. INC. 

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