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3 FIELD MUSEUM OF NATURAL HISTORY

Volume 51 NOVEMBER 28, 1966 No. 2

Evidence for Parthenogenesis in the Featherwing

Beetles, with a Taxonomic Review of a

New Genus and Eight New Species

(Coleoptera: PtiHidae).

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FIELD MUSEUM OF NATURAL HISTORY

Henry S. Dybas tv\. V^**^^'^^

Associate Curator, Division of Insects y^l^^^^ . \^w^

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Introduction

The new genus Eurygyne is a distinctive group of tiny feather-
wing beetles that is widespread in tropical and subtropical areas of
the world. Though no members of the genus have been recorded
previously from the United States, they seem to be rather abundant,
especially in Florida where seven new species occur. The beetles are
trim little forms, about 0.6 mm. long, that live in decaying organic
materials in the floor stratum. There they presumably feed on spores
and hyphae of fungi, as do other members of the family. In some
situations they may become very numerous, though only one rela-
tively huge egg is matured in the abdomen at a time.

Parthenogenesis has not been reported previously in the Ptiliidae,
but evidence for complete parthenogenesis is presented for at least
five of the eight new species of Eurygyne, and some possible reasons
for its high incidence are suggested. One of the parthenogenetic new
species has an anomalous geographical and ecological distribution in
the United States, which is discussed later.

The Bahama Island form, in contrast to all the mainland species,
is polymorphic with respect to the wings; most of the individuals have
the expanse of the featherwing greatly reduced by the loss of most

fe Library of Congress Catalog Card Number: 66-29127

I No. 1013 11 mnmi OF ILLINOli)

FEB 7 1968
UBRARY

12 FIELDIANA: ZOOLOGY, VOLUME 51

of the long marginal wing hairs, presumably as an adaptation against
being passively wafted out to sea.

The eight new species are all from the United States and the adja-
cent Bahamas and from Bermuda. Other undescribed species occur
in the New World and Old World tropics. Five nominal species from
the Old World, described in the genus Throscidium, very probably
belong to Eurygyne and are transferred to the genus though they can-
not be identified from the descriptions.

Materials and Methods

In a group of insects as tiny as the Ptiliidae, appropriate tech-
niques of collecting and sampling, of sorting and handling, and of
study and illustration, are especially important. I plan to treat these
techniques in a later paper; but it is adequate for the present to say
that the taxonomic treatment in this paper is based on structures
that cannot be studied from the traditional dry mounts, using stereo-
scopic microscopes and reflected light. There are external differences
between the new species described in the following pages, but I have
not used these differences for taxonomic purposes to any extent for
two main reasons which apply to the Ptiliidae in general. First, the
beetles are too small to study with the maximum magnifications and
illumination practical with stereoscopic microscopes. Details of the
antennae, legs, mouthparts, and other structures cannot be seen or
analyzed well. Second, many of the differences that can be seen —
slight species differences in color, pubescence, and general facies — can-
not be accurately communicated to other biologists either through
illustrations or through descriptions.

The only basis for a sound taxonomy in this genus, as in most
Ptiliidae, lies in structures, like those of the antenna and spermatheca,
that can only be studied and illustrated accurately from material
mounted on microscope slides. In Eurygyne, the spermatheca has
proved useful in differentiating the species. Constant differences
characterize species that would be difficult to separate on the basis
of external characters. A good example is furnished by E. frosti n. sp.
and E. suteri n. sp. which are similar brown species externally, but
which differ in the form of the spermatheca. A complex spermatheca
like that in intricata is not easy to interpret and illustrate, since it is
only about 0.1 mm. in greatest dimension. In the species with a sim-
pler spermatheca, where slight variations in form can be readily de-
tected, there is remarkably little variation within a species. In frosti,

DYBAS: FEATHERWING BEETLES 13

lutea, and fusca (fig. 4), for example, I have examined, respectively,
370, 2,500, and 630 females without seeing any variations which did
not fall clearly within one of the three spermathecal types.

This study is based upon about 11,400 specimens from the United
States and another 600 specimens from the adjacent Bahamas and
Bermuda. Except for E. lutea n. sp., all of the specimens of Eurygyne
were studied on permanent slide preparations (Euparal mounting
medium) or on temporary mounts (Hoyer's medium). In the case
of E. lutea, the number of specimens was so large (in excess of 9,100)
that they could not all be prepared as microscope slide mounts. In
this case, the smaller lots were completely mounted, while the larger
lots, all from Florida, were sampled after inspection in alcohol. Since
E. lutea can be readily separated from the other presently known
Florida species by its color and general facies, and by the triangu-
larly acuminate coxal lamina of the hind leg, I believe the sampling
procedure introduced no significant taxonomic or numerical error.
About 2500 specimens (more than 25% of the entire sample) were
studied on microscope slides, mostly in Hoyer's medium. Temporary
media are useful for thinly sclerotized and lightly pigmented forms
like most of the Eurygyne species, and they require much less time
for slide preparation. The data on egg size and number were ob-
tained from temporary mounts; the KOH stage in the preparation
of permanent mounts destroys the egg. After study of the temporary
slides, selected specimens were processed for permanent slides and the
rest of the specimens were returned to alcohol vials.

Unless otherwise stated (e.g., "sifting . . .," "at light") the speci-
mens reported in this paper were extracted by means of the insect
(Berlese or TuUgren) funnel. The use of this technique permits, for
the first time, the systematic sampling for Ptiliidae of the micro-
habitats in an area and the accumulation of adequate series for study.

Where the size of the series permits, specimens of the new species
of Eurygyne described in this paper are to be deposited in the follow-
ing collections: American Museum of Natural History (AMNH),
British Museum (Natural History) (BM), Canadian National Col-
lection (CNC), Illinois Natural History Survey (INHS), United
States National Museum (USNM), and the collection of Eivind
Sundt, Svartskog, Norway.

The Featherwing and Flight

Some data on the metathoracic wings are presented later in the
paper and a preliminary description of the wing is desirable as it has

14 FIELDIANA: ZOOLOGY, VOLUME 51

not been adequately described in the literature. The metathoracic
wings in Eurygyne and in most Ptiliidae show a characteristic feather-
wing structure which is convergent in a number of unrelated groups
of minute insects, notably Hymenoptera of the family Mymaridae.
The wing (fig. 8) consists of a very narrow, heavily sclerotized basal
strut and a much longer, narrow, membranous terminal portion which
has no distinct wing veins but which has thickenings in the mem-
brane. There is no thickened costal margin. The surface of the
membrane has patches of microtrichia. The membrane of the wing
is furnished with long marginal hairs which form the greater part of
the expanse of the wing. There is an interruption in the array of
marginal hairs, delimiting a terminal group from the proximal groups
of the anterior and posterior margins. Just before their sockets in
the membrane, the hairs are nearly transparent and are flexible
(fig. 10a). When the wings are folded under the elytra, the hairs
are appressed along the membrane and show through (in pale species)
as dark vittae on each side. The wing folding pattern in Eurygyne
is the same as described by Forbes (1926) for the genus Acrotrichis,
which is in a different subfamily of Ptiliidae. There are no longi-
tudinal folds as in most other beetles (Forbes, 1926), but only trans-
verse folds, presumably because the membrane is very narrow. The
first transverse fold is at the junction of the basal strut and the wing
membrane. As in Acrotrichis, the folds are convex — concave — con-
cave— convex (fig. 10b). This pattern may therefore be character-
istic of most Ptiliidae except Nossidium and related genera, which
have two parallel struts in the basal portion of the wing, a much
wider wing membrane, correspondingly shorter marginal hairs, and
a more complex wing-folding pattern (Forbes, 1926).

The convergent evolution of the featherwing in the most minute
members of unrelated groups suggests that the featherwing structure
is associated with the evolution of small size. It has been suggested
by a number of authors (cf . Barber, 1924) that the featherwings func-
tion for passive dispersal, as in the ciliate seeds of plants.

Two main explanations for the evolution of the featherwing have
been advanced. Rensch (1948) points out that in the evolution of
small size in the Diptera, the thorax fills with flight muscles until
finally a limit is reached when the thorax can no longer contain the
necessary muscles and normal flight is no longer possible. He regards
the convergent ciliated wing in Thysanoptera, Mymaridae, Tricho-
grammatidae, Ptiliidae, Sphaeridiidae, Clambidae, and minute Dip-
tera, as an adaptation which enables the insect to make use of the
viscosity of the air and to float.

DYBAS: FEATHERWING BEETLES 15

Horridge (1956), on the other hand, points out that size is in-
volved in the aerodynamics of an aerofoil like an insect wing. He
concludes that the featherwings of Mymaridae and Ptiliidae are
"operating in the range where the viscous drag forces are several
times any possible lift forces. It is probable that they have aban-
doned altogether the aerofoil action and that they literally swim in
the air." He points out that flight is still possible if there is some
mechanism by which drag on the upstroke is less than that on the
downstroke, for example, if the wings or bristles bend more easily on
the upstroke than the down. In any case, such flight would be effec-
tive only over microdistances in still air, and passive dispersal by
air-currents would seem to be the most important means of dispersal.

Eurygyne, new genus. Figures 1-14.

Throscidium auct. {nee Matthews 1872)

Type-species. — Eurygyne intricata new species.

Diagnosis. — A genus of Ptiliidae of oval, compact form with the
hind coxae broadly laminate, nearly contiguous. Prosternum ex-
tremely short in front of the anterior coxae, which are very prominent.
Mesosternum with a sharp median keel anterior to the mesocoxae;
the keel does not reach the anterior border, which is delimited as a
distinctly defined collar by a fine line. In one group of species, the
collar extends onto the mesopleural humeri. The sutures lateral to
the mesocoxae are straight, directed very slightly anteriorly, and are
marked internally by a heavy endoskeletal ridge. Metastemum rather
short, without 'metasternal lines' ; produced between the hind coxae
as a single pointed process. Abdomen without teeth at apex. Eyes
emarginate behind and furnished with a dorsal flange, forming a
pocket into which the anterior pronotal angles fit when the head is
retracted. Femora of all legs narrowly laminate. Eyes well devel-
oped. Males unknown in some species. Distribution primarily pan-
tropical and subtropical.

Description. — Form oval or elongate oval; head, pronotum, and elytra fairly
smoothly contoured when body is contracted. Head large, broad, inserted into
the pronotum to the eyes. Eyes large, prominent ventrally, emarginate behind,
modified dorsally into a backward projecting flange which, together with the emar-
gination, receives the anterior angles of the pronotum when the head is retracted.
Antennae moderately long, 11-segmented; middle segments sub-cylindrical, elon-
gate (shorter in E. wagneri), each slightly constricted at base and apex; segments
9-11 forming a loose, moderately enlarged club; segment 9, and more markedly
segment 10, constricted beyond middle, vase-shaped. Mentum large, trapezoidal,
sides slightly sinuate near base.

16 FIELDIANA: ZOOLOGY, VOLUME 51

Pronotum broader than long, sides evenly curved; basal angles not noticeably
prolonged; basal margin bisinuate near posterior angles, partly covering base of
elytra and the triangular scutellum.

Elytra long, humeri with a slight angulation; epipleurae extending about half
the elytral length.

Prosternum extremely short anterior to the coxae, which are very prominent.

Mesosternum short in front of coxae, extending little more than their greatest
diameter; with a sharp median keel that does not reach the anterior border. The
anterior border is delimited by a fine line as a distinctly defined collar. In one group
of species (wagneri group), the collar extends onto the mesopleural humeri. Meso-
pleural humeri prominent, rounded, without a dentate projection. Mesocoxal
acetabula broadly contiguous, the lateral sutures rather straight; directed slightly
anteriorly, and marked internally by a heavy endoskeletal ridge (less developed in
steevesi n. sp.). Metasternum short, about four times as broad as long; terminating
between the hind coxae as a short pointed process (not bifurcate as in the Nano-
sellini). Metendosternite as in Figure lb.

Abdomen nearly covered by the elytra, last segment partly exposed; 10-seg-
mented; tergites I-V membranous or lightly sclerotized, II-V with the character-
istic 'fingerprint' whorl pattern on each side; tergites I- VIII with a spiracle on each
side; tergite VII with posterior margin micro-pectinate; tergite X well developed,
separated from IX by a distinct straight suture, not dentate at apex. No sclero-
tized internal glands or row of 'glandular' pores (as in the Pterycini) visible.
Sternite III, which is interpreted to be the first visible sternite, is somewhat cari-
nate between hind coxae. Sternite IX in the female is an arcuate sclerite concealed
by VIII; in the male (where the male sex is present) it can be detected internally
as a spur projecting anteriorly to one side of the aedeagus.

Legs moderate in length; posterior coxae very broadly, subtriangularly lami-
nate; anterior coxae relatively large, all femora with a narrow lamina. Anterior
tibiae with one large spine at outer apex and two large spines before inner apex;
tarsi slender, with slender subequal claws that bear a seta between.

Spermatheca tubular, varying from a simple U-shaped tube (cf. E. lutea n. sp.)
to a highly coiled structure whose details are difl!icult to unravel (cf. E. intri-
cata n. sp.).

Aedeagus (in species with males) tubular; no ventral hooks present.

Remarks. — The genus is distinctive and does not seem to be closely
related to any other described genus in the Ptiliidae. In addition to
the eight new species described in this paper from the eastern United
States, the adjacent Bahama Islands, and Bermuda, five other nom-
inal species that were formerly placed in Throscidium of authors (not
Matthews, 1872) are tentatively assigned to Eurygyne. These species
are invisibilis Nietner, elongatula Mots., testaceum Britten, brunneum
Britten, and nidicola Paulian. The genus Throscidium Matthews,
1872, is thus left with only the two originally included species, ger-
maini Matth., and fairmairi Matth. from Chile. The genus Thros-
cidium, as restricted here by me, differs from Eurygyne in a number
of characters, following Matthews' original description and figures

Fig. 1. Eurygyne intricata n. g. and sp. a, dorsal view, b, ventral view.
c, egg. d, ventral view, enlarged, showing dorsal flange of eye.

18 FIELDIANA: ZOOLOGY, VOLUME 51

(I have not seen any specimens): The pronotum has the posterior
angles produced, the abdomen is tridentate at apex, the mesostemal
carina is bifurcate anteriorly and reaches the collar, the femora are
broadly laminate at apices, and the metasternum is proportionately
longer. These differences clearly preclude the inclusion in Throscidium
Matthews, 1872, of the species here assigned to Eurygyne n. g.

None of the five described species transferred from Throscidium
can be certainly identified from the descriptions, but they are very
probably congeneric with Eurygyne, and they thereby extend its dis-
tribution to Ceylon, the Seychelle Islands, Cape Verde Islands, Pan-
ama, Guatemala, and the Ivory Coast. There is also much unstudied
material, mostly in Field Museum of Natural History, that supports
the pattern of pan tropical geographic distribution. There are exten-
sive series from Middle and South America especially, but also from
Angola, the former Belgian Congo, Thailand, and other regions.
Judging from preliminary microscope-slide samples of these collec-
tions, the genus will contain numerous species once it is studied with
appropriate techniques on a world-wide basis.

The eight new species fall into two well-defined species groups.
The intricata group is characterized by the mesosternal collar being
restricted to the neck and not extending onto the mesopleural humeri
(fig. 6d). The included species are intricata n. sp., lutea n. sp., fusca
n. sp., frosti n. sp., suteri n. sp., and steevesi n. sp. In the wagneri
group, the collar extends onto the mesopleural humeri (fig. 6c). In-
cluded species are wagneri n. sp. and contorta n. sp.

The following is a brief historical resum^:

1857. Nietner described Trichopteryx invisibilis n. sp. from
Ceylon.

1867. Wollaston recorded Acrotrichis (= Trichopteryx) invisi-
bilis Nietner from Cape Verde Islands (based on an identifi-
cation by Rev. A. Matthews).

1872. Matthews described Throscidium n. gen. based on ger-
maini n. sp. and fairmairi n. sp. from Chile. No type of
genus designated.

1884. Matthews transferred Trichopteryx invisibilis Nietner to
Throscidium. Acrotrichis elongatula Motsch. (1868), de-
scribed from Panama, was listed as a synonym.

1888. Matthews, in the Biologia Centrali Americana, listed
the distribution of Throscidium invisibile Nietner as Guate-
mala, Panama, Ceylon, and Cape Verde Islands. A figure
(PI. Ill, fig. 25) of the general habitus was given.

DYBAS: FEATHERWING BEETLES 19

1926. Britten described two new species from the Seychelle

Islands: testaceum and brunneum n. spp.
1952. Paulian described nidicola n. sp. from the Ivory Coast.

KEY TO THE SPECIES OF EURYGYNE IN THE UNITED STATES
AND THE ADJACENT BAHAMAS AND BERMUDA

1. Ptiliidae with the hind coxae contiguous, or nearly so, mesosternum with a
sharp keel that does not reach the anterior margin, and with a sharply delim-
ited anterior collar; abdomen not dentate at apex; prosternum extremely short
in front of coxae; eyes emarginate behind and furnished with dorsal flange,
receiving the anterior angles of the pronotum when head is retracted; elytra
long Eurygyne Dybas, n. g. 2.

la. Without the above combination of characters. . . .other genera of Ptiliidae

(not keyed).

2. Mesosternal collar extending onto mesopleural humeri (fig. 6c).

(wagneri group) 3.

2a. Mesosternal collar not extending onto mesopleural humeri (fig. 6d).

{intricata group) 4.

3. Spermatheca as in figure 5b, c. Antennal segments shorter (fig. 5a) ; color pale;

male with a fovea on the frons E. wagneri Dybas, n. sp.

3a. Spermatheca as in figure 6b. Antennal segments longer (fig. 6a); color dark;
male sex unknown E. contorta Dybas, n. sp.

4. Spermatheca with numerous coils (fig. 2b, c). A yellow species; posterior mar-

gin of pronotum not sinuately notched near the angles; male sex known.

E. intricata Dybas, n. sp.

4a. Spermatheca with only one or two loops; posterior margin of pronotum sinu-
ately notched near the posterior angle; male sex unknown 5.

5. Yellow; apex of hind coxal lamina acuminate; spermatheca as in figure 4c.

E. lutea Dybas, n. sp.

5b. Brown or fuscous; apex of hind coxal lamina rounded, spermatheca not as
in 5 6.

6. Spermatheca as in figure 4a E. ftisca Dybas n. sp.

6a. Spermatheca as in figure 4f E. frosti Dybas n. sp.

6b. Spermatheca as in figure 7a, b E. suteri Dybas n. sp.

6c. Spermatheca as in figure 7c E. steevesi Dybas n. sp.

Eurygyne intricata, new species. Figures la-d; 2a-e; 3a-c; 9;
11; 13.

Color yellow above and beneath; eyes dark; body covered with fine inclined
golden setae. Posterior margin of pronotum not sinuately notched near posterior
angles. Suture lateral to mesocoxae heavily ridged internally. Metathoracic wings
polymorphic with respect to the number of marginal hairs. Form and chaetotaxy
of antennae and of legs as figured (figs. 2a; 3a-c). Mesosternal collar not extending
onto mesopleural humeri. Female with a distinctive, much coiled spermatheca
(fig. 2b-c). Male aedeagus in the form of a tube (fig. 2d), its internal sac with

FIELDIANA: ZOOLOGY, VOLUME 51

\^ y

Fig. 2. Eurygyne intricata n. g. and sp. a, antenna, male, b, spermatheca,
dorsal view, c, spermatheca, dorsal view, showing coils a little displaced, d,
aedeagus, ventral view, e, lateral view, showing emargination in eye which
receives the anterior angle of the pronotum when the head is retracted.

heavy sclerotizations which are visible through the walls of the aedeagus. No other
secondary sexual modifications noted.

Measurements: About .52 mm. long from the anterior margin of the pronotum
to the apex of the elytra; width about .33 mm. in slide-mounted specimens. In dry-
mounted specimens, the total length from the tip of the retracted head to the apex
of the abdomen is about .60 mm. long and .32 mm. wide.

Holotype. — A female, mounted on a microscope slide, from South
Bimini Island, Bahama Islands, collected August, 1951, by C. and
P. Vaurie. In the collection of the American Museum of Natural
History.

DYBAS: FEATHERWING BEETLES

,«^55:^

Fig. 3. Eurygyne intricata n. g. and sp. a, anterior leg, female, posterior face.
b, middle leg, female, anterior face, c, posterior leg, female, anterior face.

Allotype. — A male, same data as the holotype. In the collection
of the American Museum of Natural History.

Paratypes. — Same data as holotype, 1169 9,82crcr; same data
except June, 1951, collected by M. Cazier and C. and P. Vaurie,
59 9 9 , and 58 cf cf ; same data except July, 1951, collected by C. and
P. Vaurie, 158 9 9, 109cf cf. Paratypes in the collection of the
American Museum of Natural History and Field Museum of Nat-
ural History.

Remarks. — Eurygyne intricata resembles E. lutea most closely in
general appearance, but that species is slightly larger, the eyes are
larger ventrally, and the posterior coxae are distinctly more acumi-
nately triangular than in intricata. The specific name intricata refers
to the intricately coiled spermatheca, which easily distinguishes this
species from lutea and the other species in the intricata group.

The sex ratio, based on 582 sexed individuals, of which many are
fragmentary, is 249 cfd' (43%) and 333 9 9 (57%). Of the 333
females, each of 76 (23%) had a single relatively huge egg in the
abdomen. The egg measurement (from 24 measured eggs) averages
.31 by .18 mm. The size of the egg precludes the maturation of more
than one egg at a time in the abdomen.

22 FIELDIANA: ZOOLOGY, VOLUME 51

The metathoracic wings show an unusual kind of polymorphism
hitherto unreported in the family. In most of the individuals there
is a great reduction in the number of long marginal wing hairs that
normally account for much the greater part of the total wing ex-
panse in the Ptiliidae. An extremely reduced wing of intricata has a
fairly normal basal strut and terminal membrane, but the hairs in
the terminal group may number only ten or less (fig. 9) whereas seven
individuals with well-developed wings (of a sample of 107) averaged
50 hairs (fig. 11). Variation in the number of hairs in the anterior
and posterior proximal groups was concomitant with that of the ter-
minal group. This strong polymorphism and great variability con-
trasts sharply with E. lutea (fig. 11) and the other mainland Eurygyne,
all of which have full complements of marginal wing hairs and show
little variability. Additional remarks on the wing polymorphism are
deferred until the Discussion.

There is no obvious reason, unless it be ecological, why this spe-
cies should not yet be found on the Florida mainland. South Bimini
Island is only 60 miles off the coast of Florida, and the prevailing
southeast breezes during the summer should facilitate dispersal of the
fully-winged individuals of intricata to suitable habitats on the Flor-
ida coast.

A description of the type locality and collecting activities is given
by Vaurie (1952). Collected along with Eurygyne intricata were 12
female specimens of lutea, one female of frosti, large series of an Acro-
trichis sp., several species of Actidium, and a few Micridium sp. Ac-
cording to Vaurie (1952), "The Ptiliidae were the most numerous
Coleoptera taken. So many of them were in the debris from the
Berlese funnels that when the alcohol vials in which they were col-
lected were shaken the beetles formed a black cloud."

Eurygyne lutea, new species. Figures 4c, d; 8; 10a, b; 11; 12.

Color yellow above and beneath. Body covered with fine inclined golden setae.
Similar to E. intricata in form and in general appearance, but slightly larger and
the eyes more prominent ventrally. Collar of mesothorax not extending onto
humeri. The apex of the triangular metacoxal lamina is more acute than in E.
intricata, and in the other species of the genus. Female spermatheca a simple
U-shaped tube of diagnostic form (fig. 4c, d). Male sex unknown.

Measurements: in slide prepared specimens, about .58 mm. long from the an-
terior margin of the pronotum to the apex of the elytra. In dry-mounted speci-
mens, the total length from the tip of the retracted head to the apex of the abdomen
is .58 to .63 mm.; the width is .32 to .34 mm.

Holotype. — A female, mounted on a microscope slide, from Palma
Vista Hammock, Everglades National Park, Dade County, Florida,

DYBAS: FEATHERWING BEETLES

•S-:'

Fig. 4. a, Eurygyne fusca n. sp., spermatheca (Alabama) ventral view.
b, spermatheca (Illinois), ventral view, c, Eurygyne lutea n. sp., spermatheca
(Alabama), ventral view, d, spermatheca (Florida), ventral view, e, posterior
coxa. /, Eurygyne frosti n. sp., spermatheca, ventral view.

collected August 27, 1965, by Walter Suter, "floor-litter at buttress
of large tree." In the collection of Field Museum of Natural History.

Paratypes. — 414 females, same data as holotype. In the collec-
tion of Field Museum of Natural History.

Other records. — Florida: alachua county, Island Grove, pal-
metto-cypress-maple swamp, Aug. 22, 1965, W. Suter leg., "litter at
log with Passalus," 19 9 9 ; "litter in palm-cypress buttress," 31 9 9 ;
"debris under palmetto frond," 3 9 9; same, but at Orange Grove,
H. R. Steeves, Jr. leg., "debris at swamp edge," 32 9 9 ; 5 miles E.
of Micanopy, Aug. 22, 1965, W.S.' leg., "peripheral litter on sawdust
pile in buttress of oak," 38 9 9 ; Gainesville, pine-yellow poplar-
magnolia ravine forest, Aug. 22, 1965, W.S. leg., "debris in buttress
of yellow poplar," 6 9 9; "debris at pine buttress," 25 9 9 ; "forest
floor at log in lowland along stream," 108 9 9 . baker county,

1 Hereafter W.S. = Walter Suter.

24 FIELDIANA: ZOOLOGY, VOLUME 51

5 miles N. of Macclenny, Aug. 2, 1965, H.R.S.' leg., "debris under
palmettos and scrub," 2 9 9; Aug. 18, 1965, W.S. leg., "pine-pal-
metto buttress debris on river bank," 1 9 ; "debris in pseudo fork of
swamp white oak," 1 9 ; "bush fork accumulation," 3 9 9; Aug. 21,
1965, "bush fork accumulation," 1 9 . CALHOUN county, 1 mile
N.W. of Blountstown, July 25, 1965, W.S. leg., multiple sawdust
piles about 15 years old near swamp forest, "sawdust and litter from
periphery under magnolia shrubs," 12 9 9 ; "outwash leaf -litter at
edge of sawdust pile," 17 9 9 ; Scott's Ferry, "floor-litter under oak
and magnolia shrubs in pine woods," 3 9 9. collier COUNTY, East
of Ochopee, cypress-palmetto-maple swamp, June 17, 1965, W.S.
leg., "debris in Cypress buttress," 1 9 ; Collier-Seminole State Park,
Royal Palm Hammock, Aug. 28, 1965, W.S. leg., "litter under ferns
and bushes," 2 9 ; same, H.R.S. leg., "debris under banana trees,"

1 9 ; Monroe Station, 3 miles east, cypress swamp, Aug. 28, 1965,
W.S. leg., 72 9 9 ; same, H.R.S. leg., "hammock-like swamp grass
litter," 8 9 9. DADE COUNTY, Florida City, pine-palmetto woods,
Aug. 26, 1965, W.S. leg., "debris at pine buttress," 109 9 9 ; "de-
bris under banana tree," 74 9 9 ; same, no microhabitat data,
74 9 9 ; Everglades National Park, Palma Vista Hammock, Nov. 26,
1961, J. Wagner- leg., "floor duff," 26 9 9 ; June 18, 1965, W.S. leg.,
"floor pocket," 25 9 9 ; "debris at buttress of gumbo-limbo," 6 9 9;
"litter at logs with polypore fungi," 46 9 9 ; "stage 3 branch," 9 9 9;
"floor litter," 95 9 9 ; "litter in small limestone sink," 43 9 9 ; "floor
litter at log," 376 9 9 ; same, no microhabitat data, 180 9 9 ; H.R.S.
Jr. leg., "forest floor debris at fallen logs," 499 9 9 ; "forest floor
debris pockets, some with wood," 358 9 9 . DIXIE COUNTY, Old
Town, June 16, 1965, W.S. leg., "palmetto stump," 1 9 • FRANKLIN
COUNTY, Buck's Siding, July 21, 1965, W.S. leg., old sawdust pile
near stream, "sawdust under shrubs and briars at edge of north side
of old sawdust pile," 21 9 9 ; "litter under palmetto, sawdust pile,"

2 9 9; "litter under bushes on edge of sawdust pile," 12 9 9 . GULF
COUNTY, 6 miles N. of Weweahitchka, July 25, 1965, W.S. leg., "saw-
dust and leaves under bushes at edge of sawdust pile," 60 9 9 ; "oak
logs, stage 3," 4 9 9. HIGHLANDS COUNTY, Highlands Hammock
State Park, Aug. 23-24, 1949, H. S. Dybas leg., 9 9 9; "in decaying
grass pile," 1 9 ; "leaf litter," 1 9 ; June 19, 1965, W.S. leg., "palm
stump," 1 9 ; Aug. 24, 1965, W.S. leg., "oak log with Passalus," 2 9 ;

1 Hereafter H.R.S.=H. R. Steeves, Jr.
' Hereafter J.W.=J. Wagner.

DYBAS: FEATHERWING BEETLES 25

"debris at buttress ofcypress and oak," 1 9 ; "floor litter from drain-
age depression," 2 9 9 ; "pine-magnolia pseudo fork debris," 4 9 9;
H.R.S. leg., "debris inside palm logs," 4 9 9; "debris in pine-mag-
nolia buttress," 5 9 9; "forest floor debris," 399; "cypress swamp
debris at forest floor and at buttress," 50 9 9 ; Archbold Biological
Station, June 12, 1955, H.S.D.' leg., "decayed ditch dredgings,"
59 9 9 ; same, 20 9 9 ; same, 12 9 9 ; same, no microhabitat data,
5 9 9; "oak-pine leaves compost," 1 9 ; Nov. 15, 1959, S. W.
Frost leg., "at light," 4 9 9; "Parker Islands" east of Lake Placid,
Aug. 25, 1965, H.R.S. leg., "fern rhizome and woody debris, magnolia
swamp," 58 9 9 ; "forest floor debris, pine woods on lake shore,"
286 9 9 ; W.S. leg., "litter'at log, pine grove on lake shore," 89 9 9 ;
"debris among fern rhizomes," 86 9 9 ; "wet palm-palmetto pseudo
fork," 188 9 9 ; "stage 4 log," 19 9 9 ; "litter under ferns at oak,"
49 9 9 ; "stage 3 log," 1 9 ; "Osmunda rhizome clump," 1 9 ; "debris
at magnolia buttress," 1 9 ; "floor debris at fern rhizome," 8 9 9 ; no
microhabitat data, 15 9 9 ; Aug. 26, 1965, W.S., "floor debris at
logs," 50 9 9 ; H.R.S. leg., "fern rhizome and woody debris," 97 9 9 ;
Venus, 4 miles W., Fish Eating Creek, Aug. 25, 1965, W.S. leg.,
"grassy compost mixed with cypress, near water," 15 9 9 ; H.R.S.
leg., "grass mat at edge of cypress swamp," 45 9 9 ; same, 20 9 9 ;
southwest shore of Lake Istokpoga, June 14, 1955, H.S.D. leg., "de-
bris at base of cypress on lake shore," 1 9 ; southwest shore of Lake
Clay, near Lake Placid, June 14, 1955, H.S.D. leg., "leaf-litter in
thicket," 2 9 9; same, 599. JEFFERSON COUNTY, 1 mile east of
Capps, July 24, 1965, W.S. leg., "floor litter at log on slope to flood-
plain of pine-oak-sycamore forest," 1 9 . LEE COUNTY, Fort Meyers,
June 17, 1965, W.S. leg., "punk tree-buttress debris," 9 9 9. LEON
COUNTY, 5 miles west of lamonia (Tall Timbers Research Forest),
August 4, 1965, W.S. leg., "debris under beech logs," 1 9 ; "damp leaf
litter," 2 9 9; south of Chaires, July 19, 1965, W.S. leg., "sawdust
under bush," 2 9 9; Aug. 14, 1965, W.S. leg., sawdust pile, "sawdust
from bush-raspberry peripheral area of pile," 1 9 ; Aug. 29, 1965,
W.S. leg., "moss on logs and in buttress in adjacent swamp," 1 9 ;
same, H.R.S. leg., "sawdust pile," 4 9 9; Coe's Landing, Lake Tal-
quin, 10 miles west of Tallahassee, Aug. 17, 1965, W.S. leg., "debris
from walnut buttress near lake," 2 9 9. levy county. Manatee
Springs State Park, Sept. 12, 1959, W.S. leg., "pine-litter," 13 9 9 ;
Gulf Hammock, June 16, 1965, W.S. leg., "litter at moss covered
logs," 23 9 9 ; "magnolia(?) stump," 3 9 9; "pine buttress," 1 9 ;

1 Hereafter H.S.D.= Henry S. Dybas.

26 FIELDIANA: ZOOLOGY, VOLUME 51

"palmetto and log litter," 12 9 9 ; Bronson, June 27, 1965, W.S. leg.,
"live-oak tree hole," 1 9 . liberty county, Sumatra, July 21, 1965,
W.S. leg., "sawdust under small shrubs and raspberry on 15-year-old
sawdust pile," 5 9 9. MADISON COUNTY, 5 miles east of Lee, July 31,
1965, W.S. leg., "walnut branches with Passalus," 10 9 9 ; "pine
buttress," 5 9 9 ; 4 miles west of Madison, Aug. 21, 1965, W.S. leg.,
"floor litter at stage 3 pine(?) log," 3 9 9; "oak buttress," 599;
Mefford's Cave, Aug. 14, 1965, S. Peck leg., "debris," 1 9 . marion
COUNTY, 2 miles west of Silver Springs, June 27, 1965, W.S. leg.,
"palm log with Fomes fungus," 5 9 9; "sweet gum(?) log," 1 9 ;
"palmetto stump," 1 9 . monroe county, 5 miles north of Flamingo,
Everglades National Park, Aug. 27, 1965, W.S. leg., "grassy compost
in shade of bush, sawgrass area," 2 9 9; "litter under shrubs along
canal and Snake Bight Trail," 11 9 9 . orange county, Orlando,
July 31, 1965, W.S. leg., "pine buttress debris, pine-palmetto area,"
93 9 9 ; "grassy compost in field," 10 9 9 ; "debris in buttress of
cypress," 35 9 9 ; "floor litter under bush, cypress area," 18 9 9 ;
Aug. 22, 1965, W.S. leg., "debris in pine buttresses," 436 9 9 ;
"grassy compost on edge of swamp," 178 9 9 ; H.R.S. leg., "pine-
cypress swamp, buttress and stump debris," 382 9 9 . OSCEOLA
COUNTY, St. Cloud, Dec. 26, 1965, S.P.^ leg., "debris under dead oak
tree bark," 1 9 . pinellas county. Tarpon Springs, June 16, 1965,
W.S. leg., "cypress stump," 1 9 . sarasota county, Myakka River
State Park, June 16, 1965, W.S. leg., "palmetto," 3 9 9. seminole
COUNTY, 3 miles north of Longwood, Aug. 23, 1965, W.S. leg., "pine-
buttress," 241 9 9 ; "oak buttress," 480 9 9 ; "stage 3 linden branch
with termites," 37 9 9 ; "debris in oak buttress," 232 9 9 ; "debris
in oak-palmetto pseudofork," 210 9 9 ; "debris in oak-palm pseudo-
fork," 564 9 9 ; same, H.R.S. leg., "rotten log, palmetto debris,"
725 9 9 ; "debris, pine, palmetto buttress," 610 9 9 . suwanee
COUNTY, Falmouth, July 31, 1965, W.S. leg., "litter under oak leaves
on edge of sawdust pile in oak woods," 15 9 9 . TAYLOR COUNTY,
Athena, Sept. 12, 1959, W.S. and J.W. leg., "pine litter," 16 9 9 ;
Steinhatchee, 3 miles west, July 3, 1965, W.S. leg., "palm log on
swamp floor," 1 9 . VOLUSIA county, Osteen, Sept. 13, 1965, W.S.
and J.W. leg., "pine litter," 3 9 9; Enterprise, Sept. 13, 1959, W.S.
and J.W. leg., "pine debris," 15 9 9 ; 2 miles southwest of Enter-
prise, July 31, 1965, W.S. leg., "pine buttress, oak-pine forest,"
15 9 9 ; "oak log and floor debris, oak-pine-palmetto woods," 1 9 ;
"debris in oak buttress and fork," 2 9 9; "oak-palmetto pseudofork,

1 Hereafter S.P.=S. Peck.

DYBAS: FEATHER WING BEETLES 27

oak-pine forest," 85 9 9 ; "oak log, stage 3, on floor of oak-palmetto
swamp," 9 9 9; "oak branch, stage 3, oak-palmetto swamp," 799;
"palmetto axil debris, oak-palmetto swamp," 14 9 9 ; Aug. 23, 1965,
"decaying crown of fallen palm," 2 9 9; "oak log, stage 3," 110 9 9 ;
"oak tree hole," 16 9 9 ; "oak branch, stage 3," 13 9 9 ; "oak shrub
pseudofork, up-land," 84 9 9 ; "litter under magnolia bush," 49 9 9 ;
"palm log, lowland," 4 9 9; H.R.S. leg., "oak log," 37 9 9 . WA-
KULLA COUNTY, 2 miles north of Sopchoppy, July 21, 1965, W.S. leg.,
"buttress of pine stump in pine woods," 1 9 .

Georgia: brantley county, 1 mile east of Nahunta, Aug. 18,
1965, W.S. leg., "debris at pine buttress," 1 9 . charleton county,
St. George, Aug. 18, 1965, W.S. leg., "litter under chicken feathers
on edge of 20-year-old sawdust pile," 1 9 ; "debris at pine buttress
at edge of sawdust pile," 64 9 9 ; "litter under raspberry at edge of
sawdust pile," 6 9 9 ; 6 miles south of St. George, Aug. 18, 1965,
W.S. leg., "debris in pseudofork of magnolia (?) -yellow poplar," 1 9 ;
"debris at pine buttress with stage 3 oak log at swamp edge," 1 9 .
CLINCH COUNTY, DuPont, July 27, 1965, W.S. leg., "litter on sawdust
pile under fern and pine," 12 9 9 ; "debris at pine buttresses in woods
near sawdust pile," 2 9 9. DECATUR COUNTY, 1 mile northwest of
Climax, limestone sink at "The Cave," Aug. 12, 1965, W.S. leg.,
"debris in pine buttress," 35 9 9 . GLYNN COUNTY, 5 miles south of
Thalman, Aug. 18, 1965, W.S. leg., "pine-oak pseudofork," 1 9 ;
Jekyll Island, pine-oak-palmetto tangle near center of island, Aug. 18,
1965, W.S. leg., "oak buttresses," 1 9 . grady county, 5 miles
southwest of Beachton, Aug. 4, 1965, W.S. leg., "large wet oak log,
stage 3," 19. LOWNDES county, 2 miles east of Valdosta, July 27,
1965, W.S. leg., "debris at pine buttress," 9 9 9.

Alabama: mobile county. Mobile, June 16, 1959, J.W. leg.,
"leaf-litter, swamp forest," 3 9 9; June 6, 1960, W.S. and J.W. leg.,
"pine duff, swamp," 1 9 ; Sept. 10, 1959, W.S. leg., "magnolia leaf-
litter," 3 9 9; Sept. 11, 1959, W.S. leg., "maple-oak litter," 78 9 9 ;
"pine litter, swamp forest," 22 9 9 .

Louisiana: jefferson parish, Harahan, Aug. 24, 1944, H.D.
leg., "in decaying magnolia seed pods," 1 9 ; Sept. 26, 1944, F. Wer-
ner leg., "rotten magnolia fruit," 5 9 9. ascension parish, Gon-
zales, Oct. 16, 1953, H.S.D. leg., "in wood-borer sawdust beside
hollow, cut oak log," 1 9 .

Bermuda: Hamilton parish, Hamilton Sound, Jan. 3, 1964, W.
and J. H. Suter leg., "berlesed palmetto crotches," 1 9 ; same,
Dec. 30, 1963, "leaf-litter, scrub forest," 1 9 .

28 FIELDIANA: ZOOLOGY, VOLUME 51

Bahama Islands: South Bimini Island, June, 1951; M. Cazier
and C. and P. Vaurie leg., 4 9 9; same locality, July, 1951, C. and
P. Vaurie leg., 8 9 9 (1 callow).

Remarks. — Eurygyne lutea is most similar to E. intricata in gen-
eral appearance, but differs conspicuously in the form of the sper-
matheca and, externally, in its slightly larger size, more prominent
development of the eyes ventrally, and in the more acute apex of the
triangular lamina of the posterior coxae.

In the series of 2,500 females examined on microscope slide mounts,
there is very little variation in the spermatheca apart from variations
that can be attributed to accidents of preparation or to the distorted
condition of weakly sclerotized, callow individuals. All of the well-
prepared specimens could be definitely assigned on the basis of sper-
mathecal form alone without difficulty.

No males have been discovered in the large sample, which con-
sisted of 9,164 specimens collected in 169 lots in many localities in
four states and in the adjacent Bahamas and in Bermuda. The col-
lections were made in eight separate months of the year as well.
These data strongly support the hypothesis that lutea is a partheno-
genetic species in its present recorded range. The species probably
has a wider distribution in Middle America and in the West Indies,
at least, but the collections of Eurygyne from these regions have not
yet been studied in detail.

Unlike the situation in Eurygyne intricata, eggs were only rarely
detected in the very large sample of lutea (about 2,500 females)
mounted in Hoyer's medium on microscope slides. It is the devel-
oped chorion which shows through the abdomen and outlines the egg
in such preparations. The large yolk granules can also be detected
in many cases. In two females, each with a single, relatively huge
egg, the eggs measured .28 by .16 mm. and .32 by .18 mm., or approx-
imately one-half the total length of the beetle.

No reduction or polymorphism of the wings was noted in the ex-
tensive sample. In 123 females, representing 27 collections from 11
counties in Florida and 2 in Georgia, the number of marginal wing
hairs in the terminal group (fig. 8) ranged from 53-61, with a mean
of 57 (fig. 11). Three lutea females from South Bimini Island, Ba-
hamas, had a range of from 57-59 hairs, which is well within the
range of variation of the mainland sample.

Eurygyne fusca, new species. Figures 4a, b; 12.

Color brown; antennae, mouthparts, legs, yellow; body covered with fine in-
clined yellow setae. Collar of mesothorax not extending onto humeri. Posterior

DYBAS: FEATHERWING BEETLES

i^^-'^^<^^^it

Fig. 5. Eurygyne wagneri n. sp., a, antenna, female, b, spermatheca, ventral
view, c, spermatheca, dorsal view, d, aedeagus, ventral view.

margin of pronotum sinuately notched near posterior angles. Suture lateral to
mesocoxae heavily ridged internally. Females with spermatheca of diagnostic form
(fig. 4a, b). Male sex unknown.

Measurements: In dry-mounted specimens, the total length, including re-
tracted head and apex of abdomen, is .62-. 66 mm.; the width is .31-.32 mm.

Holotype. — A female, mounted on a microscope slide, from Fieldon,
Jersey County, Illinois, collected Aug. 3, 1959, by W. Suter and
J. Wagner, in "sawdust pile." In the collection of Field Museum of
Natural History.

Paratypes. — 189 9 9 , same data as holotype. In the collection of
Field Museum of Natural History.

Other records. — Illinois: same locality as type, Nov. 3, 1965,
H.S.D. leg., "in flight over large sawdust pile, 2:30 pm (cst), over-
cast," 1 9 .

30 FIELDIANA: ZOOLOGY, VOLUME 51

Alabama: talladega county, McElderry, Sept. 20, 1959, W.S.
leg., "berlesed sawdust pile," 5 9 9; Marshall county, Guntersville,
June 22, 1959, W.S. and J.W. leg., "berlesed sawdust pile," 1 9 ;
BIBB COUNTY, Brent, Sept. 9, 1959, W.S. leg., "sawdust pile," 35 9 9 .

Florida: leon county, Tallahassee, Sept. 15, 1944, J. H. Davis
leg., "berlesed oak-pine leaves compost," 6 9 9+7 fragm. 9 9 , 27
unsexed ; HIGHLANDS county, Archbold Biological Station near Lake
Placid, Nov. 15, 1959, S. W. Frost leg., "at light," 1 9 . Jefferson
COUNTY, Monticello (6 miles W.), July 24, 1965, W.S. leg., "beech
tree-hole," 1 9 ; same, "sawdust pile — sawdust under logs," 195 9 9 ;
same "litter pocket at logs on sawdust pile," 92 9 9 .

Mississippi: jackson county, 4 miles east of Ocean Springs,
Oct. 15, 1953, H.S.D. leg., "sifting floor litter in mixed pine-decidu-
ous forest," 4 9 9.

Maryland: Howard county, Woodstock, July 26, 1959, W.S.
and J.W. leg., "sawdust," 1 9 ; garrett county, 3 miles west of
Deer Park, July 25, 1959, W.S. leg., "sawdust," 2 9 9.

Pennsylvania: Westmoreland county, Seward, July 28, 1959,
W.S. leg., "sawdust," 25 9 9 ; south of Seward, July 24, 1959, J.W.
leg., "sawdust pile," 3 9 9.

Tennessee: mcnairy county, Selmer, Sept. 9, 1959, W.S. leg.,
"sawdust," 66 9 9 .

West Virginia: tucker county, north of Dryfork (near Har-
mon), Sept. 4, 1964, J.W. leg., "under boards in old sawdust, and
berlese of same," 7 9 9.

Remarks. — This species is easily distinguished by the form of the
spermatheca (fig. 4a, b) which shows remarkably little variation in
the approximately 630 females examined. All of the specimens seen
could be easily assigned by this one character alone. There are also
color and facies differences which cannot be described or figured well.
There are no males whatever in this sample of 630 specimens, which
consists of 18 collections from eight states. The specimens were col-
lected in five different months of the year. These data, like those for
E. lutea and E. frosti, suggest that fusca is a parthenogenetic species,
at least in the region from which it is recorded in the present study.

Several females each had a single large egg in the abdomen. Four
eggs measured .28 by .16 mm., .26 by .15 mm., .26 by .17 mm., and
.26 by .15 mm. The measured eggs all had the chorion well developed.

DYBAS: FEATHERWING BEETLES 31

The distribution of this species in the United States differs from
the pattern of the other species of Eurygyne. It is distributed widely
in the eastern United States but it has been found outside of the im-
mediate vicinity of the Gulf of Mexico only in sawdust piles left from
sawmill activities. This pattern of distribution will be analyzed in
more detail in the Discussion section of this paper.

Eurygyne frosti, new species. Figures 4f ; 13.

Color brown; antennae, mouthparts, legs and abdomen yellowish; body cov-
ered with fine inclined yellow setae. Collar of mesothorax not extending onto
humeri. Posterior margin of pronotum sinuately notched near posterior angles.
Suture lateral to mesocoxae heavily ridged internally. Females with spermatheca
of diagnostic form (fig. 4f). Male sex unknown.

Measurements: In slide-mounted specimens, the length from the anterior mar-
gin of the pronotum to the apex of the elytra, is about .53 mm. In dry-mounted
specimens, the total length, including the retracted head and apex of abdomen, is
.56-.58 mm.; the width is .30-. 32 mm.

Holotype. — A female, mounted on a microscope slide, from the
Archbold Biological Station, near Lake Placid, Highlands County,
Florida, collected Nov. 15, 1959, by S. W. Frost, "at light." In the
collection of Field Museum of Natural History.

Paratypes. — 150 9 9 , same data as holotype. In the collection
of Field Museum of Natural History and in the S. W. Frost Col-
lection. Numerous broken specimens not included in the type series.

Other records. — Florida: bay county, Panama City, July 10,
1965, W.S. leg., "grassy compost," 1 9 . COLLIER COUNTY, Collier-
Seminole State Park, Royal Palm Hammock, Aug. 28, 1965, W.S.
leg., "litter under fern and bushes," 1 9 ; same, H.R.S. leg., "debris
under banana trees," 1 9 ; 3 miles east of Monroe Station, Aug. 28,
1965, W.S. leg., "roadside grassy litter at edge of cypress swamp,"
15 9 9 . DADE COUNTY, Everglades National Park, Palma Vista
Hammock, Aug. 27, 1965, W.S. leg., "debris at buttress of large
smooth-barked tree," 1 9 ; same, H.R.S. leg., "forest floor debris,
with some wood," 1 9 . highlands county, Archbold Biological
Station, near Lake Placid, June 12, 1955, H.S.D. leg., "oak-pine
leaves compost," 4 9 9; same, no microhabitat data, 1 9 ; Highlands
Hammock State Park, Aug. 24, 1965, H.R.S. leg., "debris from for-
est floor and at buttress," 1 9 ; Aug. 23-24, 1949, H.S.D. leg., "in
decaying grass pile," 4 9 9 ; 4 miles west of Venus, Fish Eating Creek,
Aug. 25, 1965, W.S. leg., "grassy compost mixed with cypress nee-
dles," 30 9 9 ; H.R.S. leg., "grass mat at edge of cypress swamp,"
58 9 9 ; same, 16 9 9 ; "Parker Islands," Aug. 25, 1965, W.S. leg..

FIELDIANA: ZOOLOGY, VOLUME 51

Fig. 6. Eurygyne contorta n. sp., a, antenna, h, spermatheca, ventral view.

c, underside of meso- and metathorax showing collar extending onto humeri.

d, same, of E. intricata, collar not extending onto humeri.

"litter under ferns at oak," 1 9 ; H.R.S. leg., "fern rhizome and woody-
debris, magnolia swamp," 1 9 ; same, but Aug. 26, 1965, 1 9 . leon
COUNTY, south of Chaires, Aug. 29, 1965, H.R.S. leg., "sawdust pile,"
1 9 . MONROE COUNTY, 5 miles north of Flamingo, Everglades National
Park, Snake Bight Trail, Aug. 27, 1965, W.S. leg., "grassy compost
in sawgrass area," 6 9 9 ; 5 miles south of North Key Largo, Aug. 27,
1965, W.S. leg., "floor debris at log," 1 9 . orange county, Or-
lando, Aug. 22, 1965, W.S. leg., "grassy compost at edge of swamp,"
1 9 ; "grassy compost in field," 3 9 9.

DYBAS: FEATHERWING BEETLES 33

Bahama Islands: south bimini island, August, 1951, C. and P.
Vaurieleg., 19 (AMNH).

Remarks. — This species is dark in color, like E. fusca, but it is
easily separated by the form of the spermatheca, which is diagnostic.
Approximately 370 females (including fragmentary individuals) have
been studied on permanent or temporary slide preparations. The
spermatheca, though more variable than in lutea and fusca, is diag-
nostic and no variations were seen that created problems of identifi-
cation. Eight females each had a single egg which averaged .32 by
.17 mm. In 13 specimens, the apical group of wing hairs ranged from
53 to 63 and averaged 57, the same as in lutea.

The 23 collections are from seven counties in Florida and from the
Bahama Islands and span a period of six months of the year, yet all
of the approximately 370 specimens collected are females. Again, as
in E. lutea and E. fusca, the evidence points to complete partheno-
genesis in these populations.

The mouth-parts of the type series appear seemingly aberrant;
the palpiger of the labial palpi appears different from that of the other
collections of frosti, and the lacinia and galea seem to be absent in the
type specimens. In addition, the stipes is angled mesad. I have in-
terpreted these differences as artifacts of preservation and prepara-
tion. The type lot was collected "at light" and had been dried (and
perhaps subjected to other treatment as well) before being returned
to alcohol. Whatever the treatment, the natural elasticity of the
exoskeleton was not restored when the specimens were processed for
microscope slide mounts. In these seemingly aberrant mouth-parts,
the galea is hinged inward (dorsad) into the head capsule, and is not
visible, the lacinia is similarly out of view in most specimens, and the
labial palps are directed dorsad from the hinge line at the anterior
margin of the mentum, thereby showing a different angle of the palpi-
gers and an apparently different form. When two specimens of frosti
still in alcohol were dissected, the "missing" galea and lacinia were
found tucked behind the mentum and labial palpi, the galea being
folded on itself as well.

The largest collection was made "at light" at the Archbold Bio-
logical Station. This raises a problem of interpretation since Ptiliidae,
as stated earlier in this paper, have not been regarded as possessing
well-developed powers of directional flight. When only a few speci-
mens are encountered on a light sheet or in a light trap, one can
assume that Ptiliidae that are dispersing passively have been inter-
cepted by the light sheet or trap. The type lot of frosti, however.

34 FIELDIANA: ZOOLOGY, VOLUME 51

consists of more than 200 specimens taken "at light" in a single night.
Frost (1963) states that the Ptiliidae (=Trichopterygidae) came to
the lights at the Archbold Biological Station early when the light
traps were operated between 5:30 and 6:00 PM on Nov. 10-16, 1960.
"No counts were made of the Trichopterygidae, but observations re-
vealed that they came decidedly before 6 PM, usually within a few
minutes and sometimes in enormous numbers, striking against the
baffles of the trap like buckshot." If these actually represented an
intercepted sample of passively floating Ptiliidae, there must have
been astonishing numbers floating in the air. The "at light" sample
submitted by Dr. Frost contained four species of Eurygyne, of which
frosti accounted for most of the collection.

Eurygyne suteri, new species. Figures 7a, b; 13.

Color light brown, antennae and mouth parts yellow; body covered with fine
recumbent yellow setae. Collar of mesothorax not extending onto humeri. Suture
lateral to the mesocoxae marked for its full length by a heavy internal skeletal
ridge. Females with spermatheca of diagnostic form (fig. 7a, b). Male sex unknown.

Measurements: In slide-mounted specimens, the length from the anterior mar-
gin of the pronotum to the apex of the elytra is about .54 mm.; the width is about
.32 mm.

Holotype.—A female, mounted on a microscope slide, from Palma
Vista Hammock, Everglades National Park, Dade County, Florida,
collected August 27, 1965, by Walter Suter, from berlese sample of
floor litter in buttress of large smooth-barked tree. In the collection
of Field Museum of Natural History.

Paratypes. — Same data as holotype, 5 9 9 (1 callow); "litter in
small, limestone sink," 3 9 9; "floor litter on slope from road into
swamp," 5 9 9 ; no microhabitat data, 8 9 9 (1 callow); same data
but H. R. Steeves, Jr. leg., "pockets of forest floor debris, some with
wood," 1 9 ; "forest floor debris at fallen logs," 2 9 9. collier
COUNTY, 3 miles east of Monroe Station, Aug. 28, 1965, H. R. Steeves,
Jr. leg., "hammock-like swamp grass litter," 1 9 ; same data except
"roadside grassy litter at edge of swamp," 5 9 9. DADE COUNTY,
Florida City, Aug. 26, 1965, W. Suter leg., "no microhabitat data,"
1 9 . HIGHLANDS COUNTY, 4.5 miles west of Venus, at Fish Eating
Creek, Aug. 25, 1965, H. R. Steeves, Jr. leg., "grass mat at edge of
cypress swamp," 7 9 9; same locality, W. Suter leg., "grassy com-
post mixed with cypress needles near water," 2 9 9. ORANGE
COUNTY, Orlando, Aug. 22, 1965, "grassy compost at edge of swamp,"
1 9 ; "litter at pine buttress," W. Suter leg., 1 9 (callow).

DYBAS: FEATHERWING BEETLES

Remarks. — This species is similar to E. frosti, but is lighter in
color. It is easily separated from all the other species by the diagnos-
tic form of the spermatheca. The 46 specimens examined, from 15
collections, were all females; no males have been found. The sample

Fig. 7. a, Eurygyne suteri n. sp., spermatheca, ventral view, b, same, another
individual, showing variation, c, Eurygyne steevesi n. sp., spermatheca, ventral
view.

is not large but, in view of the pattern of parthenogenesis within the
genus, it is likely that E. suteri is also a completely parthenogenetic
species, at least in the range here recorded. One female had a single,
relatively huge egg in the abdomen that measured .32 by .20 mm.,
or half the length of the animal. In 20 females, the apical group of
wing hairs ranged from 57 to 64 with a mean of 61.

Eurygyne suteri Dybas was invariably collected in the field with
the far more abundant lutea. The 15 berlese samples in which the
46 specimens of suteri were found also contained 2,815 female speci-
mens of lutea, 190 female frosti (8 lots), 114 female contorta (4 lots),
15 specimens of wagneri (2 lots), and one female of steevesi. Thus,
it is an extremely minor component of the Eurygyne fauna of the
United States, at least in the microhabitats sampled so far.

Eurygyne steevesi, new species. Figures 7c; 13.

Color brown, collar of mesothorax not extending onto mesopleural humeri.
The suture lateral to the mesocoxae, not marked with a heavy internal skeletal
ridge except near coxa. Female spermatheca of diagnostic form, as shown in Fig-
ure 7c. Male sex unknown.

36 FIELDIANA: ZOOLOGY, VOLUME 51

Measurements: In slide-mounted specimens, the length from the anterior mar-
gin of the pronotum to the apex of the elytra is .51 mm.; the width of the pronotum
is .32 mm.

Holotype. — A female, mounted on a microscope slide, from Florida
City, Dade County, Florida, collected Aug. 26, 1965, by Walter
Suter, in debris under banana. In the collection of Field Museum
of Natural History.

Paratypes. — Same data as type, 1 9 ; DADE COUNTY, Everglades
National Park, Palma Vista Hammock, Aug. 27, 1965, H. R. Steeves,
Jr. leg., "forest floor debris at fallen logs," 1 9 .

Other recorrf.— HIGHLANDS county, Archbold Biological Station,
near Lake Placid, Nov. 15, 1959, S. W. Frost leg., "at light" (speci-
men later lost), 1 9 .

Remarks. — This species is easily distinguished by the diagnostic
form of the spermatheca. It also differs from all the species described
in this paper in the condition of the suture lateral to the mesocoxae,
which is marked internally by a heavy endoskeletal ridge only near
the coxa; laterally it is a fine surface suture. Since only four females
have been seen, it is not possible to say at present whether the spe-
cies is parthenogenetic or not. In one specimen, the number of wing
hairs in the apical group is 56 in one wing and 53 in the other.

Eurygyne wagneri, new species. Figures 5a-d; 13.

Color yellow-brown. Collar of mesothorax extending onto mesopleural humeri
(fig. 6c). Middle antennal segments short, as in figure 5a. The suture lateral to
the mesocoxae marked internally by a heavy endoskeletal ridge. Spermatheca of
female as in figure 5b, c. Male aedeagus as in figure 5d. Male with a median fovea
on front of head.

Measurements: Length from anterior margin of pronotum to apex of elytra:
in males, .45-. 50 mm.; in females, .48-. 51 mm.; width of pronotum: .27-.29 mm.

Holotype. — A female, mounted on a microscope slide, from Florida
City, Dade County, Florida, collected Aug. 26, 1965, by Walter Suter,
"debris under banana," in pine-palmetto woods. In the collection of
Field Museum of Natural History.

Allotype. — A male, mounted on a microscope slide, same data as
the holotype. In the collection of Field Museum of Natural History.

Paratypes. — Same data as the holotype, 24 9 9 , 16 cf' cf ; same,
but no microhabitat data, 4 9 9 , 10 cT d^ . Everglades National Park,
Palma Vista Hammock, Nov. 26, 1961, J. Wagner leg., "floor duff,"
2 9 9 , 1 cf ; same locality, Aug. 27, 1965, W. Suter leg., no micro-
habitat data, 1 9 .

38 FIELDIANA: ZOOLOGY, VOLUME 51

Remarks. — This species is related to Eurygyne contorta in the form
of the mesothoracic collar, the delimiting line of which extends onto
the mesopleural humeri, as in Figure 6c. The females differ from con-
torta by the pale color, and from it and all the other species described
in this paper by the shorter antennal segments (fig. 5a), and the shape
of the spermatheca. The males can be separated from the only other
males known so far, those of intricata, by the condition of the meso-
thoracic collar, the short antennal segments, and the presence of a
fovea on the frons.

One of the females had a single large egg in the abdomen that
measured .33 by .22 mm. In 43 specimens (210^0", 22 9 9), the
wing hairs in the apical group ranged from 36-49, with a mean of 44.
There was no significant variation between the sexes in the wing hairs.

Eurygyne wagneri is the only species on the mainland of the United
States in which the male sex is known. The sex ratio in the 60 speci-
mens known is 33 9 9 : 27c^ c^.

Eurygyne contorta, new species. Figures 6a-c; 13.

Color brown, shining; antennae, legs, and underside of abdomen lighter; sparsely
covered with light-colored, inclined hairs. Body elongate-oval and somewhat flat-
tened in form. Collar of mesothorax, extending onto mesopleural humeri (fig. 6c).
Suture lateral to mesocoxae marked internally by a heavy endoskeletal ridge. An-
tennae as in Figure 6a. Spermatheca (fig. 6b) more convoluted than in the related
wagneri. Male sex unknown.

Measurements: Length of slide-mounted specimens from anterior margin to
apex of the elytra, .51 mm.; width, .28 mm.

Holotype. — A female on a microscope slide, from Fish Eating
Creek, 4 miles west of Venus, Highlands County, Florida, collected
Aug. 25, 1965, by Walter Suter, "cypress swamp, in grassy compost
mixed with cypress needles near water." In the collection of Field
Museum of Natural History.

Paratypes. — Same data as holotype, 21 9 9 ; same, H. R. Steeves,
Jr. leg., "cypress swamp, grass mat at edge," 99 9 9 .

Other records.— Florida: collier county, east of Ochopee,
June 17, 1965, W.S. leg., "cypress buttress in cypress-palmetto-maple
swamp along U. S. highway No. 41," 1 9 . dade county, Everglades
National Park, Palma Vista Hammock, Aug. 27, 1965, H.R.S. leg.,
"forest floor debris at fallen logs," 1 9 . highlands county, Arch-
bold Biological Station, near Lake Placid, Nov. 15, 1959, S. W. Frost
leg., "at light," 1 9 ; same, June 19, 1965, W.S. leg., "pine buttress
in pine-palmetto stand," 2 9 9; "Parker Islands," Aug. 25, 1965,

DYBAS: FEATHERWING BEETLES

0.1 mm

Fig. 9. Eurygyne intricata n. sp., metathoi
of marginal hairs in a polymorphic population,

, metathoracic wing, showing a reduced stage

inniilat.inn.

W.S. leg., pine-oak grove, "litter under ferns," 1 9 ; "litter at log,"
1 9 ; H.R.S. leg., "forest floor debris," 1 9 ; Highlands Hammock
State Park, Aug. 24, 1965, H.R.S. leg., "forest floor debris, and at
buttress," 9 9 9. SEMINOLE COUNTY, 2 miles north of Longwood,
Aug. 23, 1965, H.R.S. leg., pine-oak-palmetto forest, "debris from
palmetto under rotten log," 1 9 ; 3 miles north of Longwood, W.S.
leg., "oak-palmetto pseudofork," 2 9 9; volusia county, 2 miles
southwest of Enterprise, Aug. 23, 1965, H.R.S. leg., "oak log," 1 9 .

Remarks. — This species is more elongate and more flattened in
form than the members of the intricata group. It is most closely re-
lated to wagneri in the condition of the collar of the mesothorax, but
differs in the form of the spermatheca and the proportions of the an-
tennal segments. Four females each had a single egg that averaged
.32 by .20 mm. In 22 females, the apical group of marginal wing
hairs ranged from 56-62, with a mean of 60.

40 FIELDIANA: ZOOLOGY, VOLUME 51

All of the 142 specimens are females; no males are known. Since
these represent 13 collections made over a span of six months in five
counties in Florida, it is very probable that contorta, too, is a com-
pletely parthenogenetic species, like most of the Eurygyne species
described in this paper.

Discussion

Though no species of Eurygyne have been previously recorded
from the United States, the genus is clearly a dominant group of
featherwing beetles in the floor stratum of Florida. To illustrate this,
I have tabulated comparable collections made in the summer of 1965
in 30 counties that span the whole state of Florida. The collections
were all made by the same person. Dr. Walter Suter of Carthage
College, and total 12,151 Ptiliidae representing at least ten genera.
Parenthetically, this is probably the finest sample of Ptiliidae of the
floor stratum of a geographic area ever made. Of this total, the speci-
mens of Eurygyne number 5,723, or 47%.

If, on the other hand, the percentages are calculated separately
for northern versus peninsular Florida, a significant difference ap-
pears. I have selected a more or less arbitrary dividing line roughly
at the point of greatest constriction near the base of the peninsula
(fig. 14). For convenience, the three counties (Levy, Marion, and
Volusia) dissected by this line are assigned to peninsular Florida.
South of this line, in peninsular Florida, there are 8,075 Ptiliidae from
13 counties in the sample. The Eurygyne number 4,975 specimens,
or 62%. North of this line there are collections from 17 Florida
counties, totalling 4,076 Ptiliidae, of which 748, or 18%, are Eury-
gyne. Thus, there is a striking drop in the proportion of Eurygyne as
one leaves peninsular Florida. The same pattern appears in the num-
ber of species of Eurygyne — all seven known U. S. species occur in
peninsular Florida, but only three of these have been collected out-
side this area in the United States. These facts merely reflect, I be-
lieve, the essentially tropical distribution of the genus Eurygyne.

Parthenogenesis has not been reported before in the Ptiliidae, but
the evidence presented in this paper strongly supports its occurrence
in five species of Eurygyne. These species are frosti, lutea, fu^ca, con-
torta, and suteri, of which I have examined 370, 2,500, 630, 142, and
46 females, respectively, without seeing a single male. Males are
known for only two of the eight species described in this paper. One
of these is wagneri from Florida, which has a roughly even sex ratio

DYBAS: FEATHERWING BEETLES 41

in the 60 specimens known; the other is intricata from South Bimini
Island off the coast of Florida, which has a sex ratio of 43% males
and 57% females in the 581 specimens that were sexed. The last new
species, steevesi, is only known from three collections totalling four
females, so judgment must be suspended as to its condition. Thus,
of the eight new species described in this paper, two are definitely
bisexual, five appear to be parthenogenetic, and the condition of one
is uncertain.

Not all the evidence, though, is consistent with the hypothesis of
complete parthenogenesis in Eurygyne. A spermatheca is a nonfunc-
tional structure in a completely parthenogenetic species. Such non-
functional structures ought to become vestigial in time, or, at least,
ought to become more variable because of less stringent selection.
Yet all the presumptively parthenogenetic species retain the sper-
matheca in apparently functional form and, moreover, exhibit little
variability in this structure.

Alternative hypotheses to that of complete parthenogenesis, are
that males are produced only at certain times of the year, or that they
have unusual habits which would prevent their being collected with
the females, but such sexual differences are unknown in any Ptiliidae.
Another possibility is that we may be sampling peripheral partheno-
genetic populations of species which have males in one part of the
range and not in another, in which case the species as a whole is not
completely parthenogenetic. Suomalainen (1962), in a recent review
of parthenogenesis in insects, cites several cases in which a given spe-
cies is bisexual in one area and parthenogenetic in another. The weevil
genus Otiorrhynchus, for example, has at least ten species of this kind
in Europe. In most of these, the bisexual races occur outside the
areas covered by ice during the Wiirm glaciation, while the partheno-
genetic races have, for the most part, spread into the areas later freed
from ice. Suomalainen suggests possible reasons for these different
distributions in the parthenogenetic and bisexual races in Otiorrhyn-
chus. A somewhat similar case has been presented by Reichle (in
press) on a species of beetle of the family Pselaphidae (Bythinopsis
tychoides Brendel) that is found in bogs in northeastern United States.
There is a roughly equal sex ratio in New York and New Jersey;
whereas west of the Allegheny Mountains, only females have been
collected.

The range of Eurygyne, on the basis of unpublished data as well
as on the localities recorded in this paper, is primarily tropical. Its
northern extension into the United States may well be a peripheral

42 FIELDIANA: ZOOLOGY, VOLUME 51

dorsal
base

apex

ventral

Fig. 10. Eurygyne liitea n. sp., a, portion of a marginal wing hair, showing
transparent, flexible basal portion, and insertion in socket in wing membrane.
b, diagram of wing-folding pattern. In the terminology of Forbes (1926) the trans-
verse folds are convex — concave — concave — convex.

one, and the main ranges of the species treated here may be in the
West Indies or in Middle and South America where the genus has not
yet been studied. When the more tropical components of Eurygyne
are studied, the pattern of parthenogenesis may appear to be different.

Returning to the problem of the 'non-functional' spermatheca, a
simple explanation for its uniformity, in view of relaxed selection,
suggests itself. The two main sources of genotypic variation in bi-
sexual species are gene flow and recombination (see Mayr, 1963, for
a recent review) . In a completely parthenogenetic species, gene flow
is precluded and recombination of genes is no longer possible, at least
between different individuals. Segregation within an individual may
be possible depending on whether the parthenogenesis is of the mei-
otic or ameiotic type (White, 1954) . In any case, mutation is left as
a main immediate source of genotypic variability in a completely
parthenogenetic form. In such a species, the accumulation of viable
mutations in the loci affecting the form and structure of the sper-
matheca may be so slow as to have little effect on its variability over
long periods of time. This alone may account for the retention of an
apparently functional spermatheca, and its low variability in the pre-
sumptively parthenogenetic species of Eurygyne.

Nothing is known, of course, of the cytogenetics of Eurygyne, but
in the Otiorrhynckus weevils, all of the parthenogenetic species stud-

DYBAS: FEATHERWING BEETLES 43

intricata ^ lutea

1 j South Bimini Island U.S. mainland

n= 107 n= 123

u. 20 :

n "' "I

NUMBER OF MARGINAL WING HAIRS IN APICAL GROUP

Fig. 11. Graph of number of marginal wing hairs in apical group in Eurygyne
intricata n. sp. and lutea n. sp.

ied to date are polyploid. In those cases, as stated by Suomalainen
(1962), "the newly arisen mutations have difficulty expressing them-
selves, as they are counterbalanced by several doses of the original
allele."

Because recombination of genes between different individuals is
no longer possible in parthenogenetic forms, their genetic systems are
presumably at a disadvantage in the long run because of the lack of
adaptability to changing circumstances. In the short run, though, a
completely parthenogenetic species may be quite successful. Most
of the parthenogenetic Otiorrhynchus weevils have larger ranges than
their bisexual relatives (Suomalainen, 1962), though here the factor
of polyploidy is also involved.

The advantages of parthenogenesis (White, 1954, and Suoma-
lainen, 1962) include these: 1) parthenogenesis permits the fixation
of genotypes particularly favorable for special situations; 2) it facili-
tates expansion into new areas because any individual at any stage
of development can establish a population in a favorable place; 3) it
increases fecundity by a factor of two because all of the eggs can pro-
duce females — none are 'wasted' (Mayr, 1963) on males. There are
also some other possible genetic advantages (Dobzhansky, 1951).

All of these advantages may apply to the parthenogenetic species
of Eurygyne; but the third point, the increase in fecundity, seems par-
ticularly relevant. Earlier, it was shown that only one relatively huge

44 FIELDIANA: ZOOLOGY, VOLUME 51

egg is matured in the abdomen at one time. This is true of the two
bisexual species, E. intricata and wagneri, as well as of five partheno-
genetic species, E. lutea, fusca, frosti, contorta, and suteri, so it very
probably holds throughout the entire genus. These mature eggs are
approximately one-half the total length of the entire body! In some
other unrelated genera in the Ptiliidae (e.g., five genera of U. S.
Pterycini, unpublished data), there is similarly only one large mature
egg at a time, indicating that this habit may be widespread in the
family. The Ptiliidae have active staphyliniform larvae (Hinton,
1941, and unpublished data) and their eggs must be provided with
enough yolk for embryogenesis to continue until the highly organized
larva is fully formed and self-sufficient. Presumably, this explains
why there must be such a relatively large egg in such a small insect.
Rensch (1948) has pointed out that one of the consequences of evo-
lution toward small size in arthropods is a reduction in the number
of eggs that can be accommodated and matured in the abdomen, be-
cause each egg must be furnished with sufficient yolk to complete
embryogenesis; in the extreme case there is room for only one egg.
Rensch regards egg number and egg size as important factors in set-
ting lower limits to the evolution of small size in arthropods.

There are no data on how long a female featherwing beetle may
live and reproduce nor on how long it takes a single egg to mature.
It would seem, though, that a low average fecundity per female must
be postulated. This is difficult to reconcile with the high densities of
Ptiliidae encountered in some temporary microhabitats, and with the
passive dispersal suggested by the structure of the metathoracic wings,
a method of dispersal that implies considerable wastage of individ-
uals. When more is known about these little animals, the apparent
discrepancies in these statements may be reconciled. For one thing,
there may have been a compensating increase in the rate of develop-
ment as evolution progressed toward small size and fewer eggs. Un-
fortunately, there is almost no information on rates of development
in the Ptiliidae. The only data in the literature (Hinton, 1941) sug-
gest a period of development of three weeks from egg to adult in
Acrotrichis fascicularis (Herbst) which is only remotely related to
Eurygyne. Featherwing beetles seem to reproduce continuously rather
than seasonally, judging by the presence of larvae and callow adults
at different periods of the year. Thus, the 'innate capacity for in-
crease' (Andrewartha and Birch, 1954) may well be substantially
greater than the minimal egg number implies.

rt.22

CO w.

• ii

C O

^ O
^ w

K3-^

•r 0)
1^

46 FIELDIANA: ZOOLOGY, VOLUME 51

In any case, the sudden doubling of a critically low fecundity
through parthenogenesis, may confer a large selective advantage on
a clone imbedded in a biparental population^ — a very large advantage,
even when compared with the magnitudes of selective pressures now
being discovered in natural populations (Ford, 1964). Though this
may be of short-range evolutionary advantage, it does not preclude
the temporary success of parthenogenetic populations in those in-
sects, with appropriate genetic potentialities. If, indeed, increased
fecundity is a major advantage of parthenogenesis, there should be a
higher incidence of parthenogenesis in groups where evolution toward
small size has greatly reduced the number of eggs produced. The
Ptiliidae, on these grounds, ought to provide a test of this prediction
once they are better known. As mentioned earlier, the genus Eury-
gyne will probably have many more species throughout its pantrop-
ical range when studied with appropriate techniques. In connection
with general problems of parthenogenesis and evolution, there is ob-
viously an advantage in studying a genus that has numbers of both
kinds of species. Patterns with respect to geographic range, micro-
habitats, variation, numbers, and other population aspects may be-
come evident when enough parthenogenetic and bisexual species with-
in a single genus are studied and compared.

There is a further point. With one exception, the genus Eury-
gyne in the United States, according to present records, is restricted
to Florida and to the southern portions of the Gulf states of Louisi-
ana, Mississippi, and Alabama (figs. 12, 13). The northern limit is
essentially defined by the winter isotherm of 50° F. The exception
to this pattern isfusca, most of whose records are from sawdust piles
left from sawmill activities north of this line; none is from a 'natural'
microhabitat. South of this line, however, in addition to records from
sawdust piles (Leon and Jefferson counties in northern Florida), there
are small collections from "oak-pine leaves compost," "at light," and
"sifting floor-litter in mixed pine-deciduous forest." These are pre-
liminary data and much more sampling needs to be done before defin-
itive conclusions can be drawn; nevertheless, they form a consistent
pattern. The genus is clearly tropical and subtropical and, in the
United States, its distribution is centered in Florida where all seven
U. S. species occur. Only two species are recorded from outside the
state of Florida; one of these, lutea, is restricted in the United States
to the vicinity of the Gulf of Mexico. The evidence, then, suggests
that the parthenogenetic species fusca is able to extend its range out-
side the main Eurygyne range into 'artificial' microhabitats provided

DYBAS: FEATHERWING BEETLES

▲ frosti

H) suteri

^ wagneri

•tr steevesi

O contorta

B intricata

Bahama Is.

South Bimini I.

Fig. 13. Distribution map of Eurygyne species. Each symbol may represent
one or several collections within a county or island. None of the species plotted
is presently known to occur outside the area shown in the map.

by sawdust piles in the woods. Perhaps its spread into these situa-
tions is facilitated by its parthenogenesis; any individual encounter-
ing a favorable sawdust pile can establish a population.

Sawdust piles, it can be assumed, provide a warm, buffered en-
vironment that is relatively stable over long periods of time. Oxida-
tion provides heat which is dissipated slowly through the well-insu-
lated mass; a large pile is quite hot in the center. It may require five
to ten years for a sawdust pile to acquire an appreciable micro-fauna,
which may then persist for a number of years, perhaps up to twenty
(Suter, personal communication). At present it is still not possible
to say from which microhabitat of the forest floor, or its extensions,
most of the sawdust pile fauna is derived. Eurygyne fusca is known
from a few collections made in forest-floor litter but most of the rec-
ords are from sawdust piles.

A new sawdust pile is a kind of sweepstakes situation, as suggested
in conversation by my colleague Dr. Monte Lloyd. The chances of a
given female finding a suitable pile are extremely small, true, but once
the pile is found, the ecological opportunity for a rapidly expanding

FIELDIANA: ZOOLOGY, VOLUME 51

Percentage of Eurygyne
Among All Ptiliidae Collected

Fig. 14. Percentage of specimens of Eurygyne in comparable collections of
Ptiliidae from the floor stratum in northern Florida, as contrasted with peninsular
Florida. The collections were all made by one person (Walter Suter) in one sum-
mer (June to August, 1965). The northern collections total 4,076 Ptiliidae from
17 counties, and the peninsular collections total 8,075 Ptiliidae from 13 counties.
There is a marked drop in the percentage of specimens of Eurygyne in the collec-
tions of Ptiliidae in northern Florida, and a similar drop in the number of species
represented.

population is great, especially for a parthenogenetic species \ikefusca.
Moreover, a large sawdust pile probably provides a favorable, stable
environment, in one part or another, over a period of many years; the
sawdust pile at the type locality near Fieldon, Illinois, still contained
fusca after six years in 1965, and one dispersing female was collected
floating in the air above the pile. Sawdust piles seem to have rela-
tively few species of beetles, mostly in the families Ptiliidae, Pselaphi-
dae, Scydmaenidae, Histeridae, and Staphylinidae, but these are char-
acteristically present in large numbers (Suter, Wenzel, Wagner, per-
sonal communications). There may be further genetic advantages
to parthenogenesis in such large populations established by single
founders. A closely inbreeding bisexual population, derived from a

DYBAS: FEATHERWING BEETLES 49

single fertilized female, provides the conditions for increasing homo-
zygosity and the expression of deleterious recessives, and may thus
result in a lower level of fitness of the population.

A similar pattern of a southern insect maintaining itself in favor-
able microhabitats in northern localities — again in sawdust piles — is
seen in Zorotypus hubbardi (order Zoraptera). The distribution of
this species has been worked out in detail by Gurney (1959), Riegel
and Ferguson (1960), and Riegel (1963). In the southern states of
Florida, Mississippi, Louisiana, and South Carolina, this species oc-
curs under the bark of stumps and in logs; but in most of its recorded
range, which extends north to Delaware and Pennsylvania in the east,
and Iowa, Kansas, and Oklahoma to the west (see map in Riegel,
1963), it occurs almost exclusively in sawdust piles. For example,
of 34 collections in eight states outside the Gulf states region, all but
one were from sawdust piles (Riegel and Ferguson, 1960), and Riegel
(1963) believes that the species can maintain itself in the north only
by chance colonizations of temporarily favorable sawdust heaps.

Finally, it has been shown that Eurygyne intricata, in contrast to
all the other species described in this paper, is strongly polymorphic
with respect to the number of marginal hairs of the metathoracic
wings (figs. 9, 11). Since the marginal hairs account for much the
greater part of the expanse of the wing, it is highly probable that the
individuals with great reduction in marginal hairs are unable to use
their wings for passive dispersal. Of 107 specimens of intricata stud-
ied, 7 or 63^% had a full complement of marginal hairs (an average
of 50 in the apical group) while the rest showed an extreme but vari-
able degree of reduction. This suggests a balanced polymorphism
resulting from conflicting selective forces (for recent reviews see
Mayr, 1963, and Ford, 1964). The polymorphic population of intri-
cata was collected on South Bimini Island in the Bahamas. The
island is only 4 by l^/^ miles in extent, has a low relief, and is sub-
jected to prevailing southeast breezes during the summer when the
collections were made (Vaurie, 1952). Under these circumstances
there is probably strong selection against fully-winged individuals
because of the hazard of being wafted out to sea and lost.^ On the
other hand, there is undoubtedly need for dispersal between habitats
on the island and between islands from time to time, hence selection

1 Since this was written, a comparable situation in wind-dispersed seeds has
been reported by Carlquist (1966). In the seeds of certain mainland Compositae,
the pappus is well developed and functions for aerial flotation, while in related
Pacific island species, the pappus is greatly reduced, with correspondingly dimin-
ished powers of dispersal.

50 FIELDIANA: ZOOLOGY, VOLUME 51

for some fully-winged individuals in the population. When other
populations of intricata are discovered, it will be of interest to com-
pare the degree of polymorphism of the wings with reference to the
habitat.

Acknowledgements

I am indebted to many individuals and institutions for specimens
and for help of various kinds. Among these are the Archbold Bio-
logical Station, Lake Placid, Florida, in the persons of Richard Arch-
bold and L. J. Brass; the American Museum of Natural History,
particularly Mrs. Patricia Vaurie, Dr. Jerome G. Rozen, Jr., and
Dr. Mont Cazier (present address: Arizona State University) and the
Illinois Natural History Survey (Drs. H. H. Ross and L. Stannard).
Dr. S. W. Frost, The Pennsylvania State University; Dr. John Wag-
ner, Kendall College; Dr. Orlando Park and Stewart Peck, North-
western University; and Dr. Floyd Werner, University of Arizona,
have provided many specimens. Harrison R. Steeves, Jr., Birming-
ham, Alabama, has provided rich collections of Eurygyne from south-
ern Florida. Above all, I am indebted to Dr. Walter Suter, Carthage
College. He has systematically and carefully sampled the micro-
habitats of the floor stratum and its extensions in many parts of the
United States over the years, and his collections form the major part
of the material upon which this study is based.

Dr. Robert Inger of Field Museum of Natural History and Dr.
Monte Lloyd, University of California (Los Angeles) have critically
reviewed parts of the paper and discussed the ideas with me. My
colleague. Dr. Rupert Wenzel has read the paper and contributed a
number of helpful suggestions. Mrs. Gail Dittmer has also read the
paper carefully and helped in many ways. I owe especial thanks to
Mr. Christian Y. Oseto for technical aid of various kinds, including
microscope slide preparations and preparation of the distribution
maps and several of the illustrations.

Finally, I wish to gratefully acknowledge the help of the National
Science Foundation (Grant GB-2697) with whose financial support
much of the work was accomplished.

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Full text of "Evidence for parthenogenesis in the featherwing beetles, with a taxonomic review of a new genus and eight new species (Coleoptera: Ptiliidae)"

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