Studies on Spiroboloid millipeds. IX. a second Typhlobolellid genus from Mexico

FIELDIANA "j-s 1973
Zoology

Published by Field Museum of Natural History

. ■■ J^

Volume 62, No. 3 June 15, 1973 ^^

Studies On Spiroboloid Millipeds. IX. %%^ ^

A Second Typhlobolellid Genus From Mexico ^^ '^ v

Radford College, Radford, Virginia ^

Richard L. Hoffman "^^^

In connection with a synopsis now in preparation of the known
cambaloid genera of the world, I became interested in the status of
Ergene setosus, a supposed member of the family Leioderidae de-
scribed by R. V. Chamberlin in 1943 from two female specimens
taken in Tamaulipas. As all other members of that group are con-
fined to California, it seemed possible to me that perhaps Dr. Cham-
berlin may have had material of a small species of Cambala in which
the tergal crests were suppressed, and that this notion could be veri-
fied even though the types were females.

Dr. John Kethley generously responded to my inquiry about this
material (property of Field Museum of Natural History) by promptly
loaning it for study. The one complete specimen in the vial (a second
is represented only by the head) proved to be an adult male, not of a
cambaloid form, but of a spirobolellid species which is obviously
closely related to Typhloholellus whiteheadi, described by me in 1969 ^
Although partaking of the major anatomical features of the latter
species, Ergene setosa (the generic name is actually feminine) is none-
theless endowed with a variety of distinctive characters, which I take
this occasion to illustrate and discuss. The zoogeographic anomaly of
a "leiodereid" genus in eastern Mexico is, of course, automatically
disposed of at the same time.

1 Described in the wrong order] Not the first time such a level of confusion has
occurred involving supposed cambaloids. In 1946 Chamberlin redescribed the
well-known spiroboloid Pseudospirobolellus bulhiferus (Attems) under the name
Saipanella mariana and referred it to the Cambalidae; in 1936 Graf Attems de-
scribed a species of Bollmania (Lysiopetalida: Caspiopetalidae) in his new genua.^
Apatidea which he likewise placed in the Cambalidae. ^. ««*Y \j\^n"^

Library of Congress Catalog Card Number: 73-79268 \0\ ^^

Publication 1166 29

MAR 0 8 19^

30 FIELDIANA: ZOOLOGY, VOLUME 62

Family Spirobolellidae Brolemann

Subfamily Typhlobolellinae Hoffman

The two genera referred to this subfamily have in common the
following structural features which set them apart from other spiro-
bolellids and, in fact, from all other members of the order Spirobolida:
ocelli completely absent; ozopore series beginning on the 3rd segment;
one or two of the podomeres with prominent armature on the dorsal
surface; metaterga continuous behind metasterna. Further, the
body is unusually long and slender, having the form and proportions
of a cambaloid rather than a spiroboloid milliped, and the antennae,
perhaps in compensation for the loss of ocelli, are long and slender.

These genera, each so far monotypic, are referred provisionally to
the Spirobolellidae rather than to a family of their own because of the
obvious evidence of gonopod structure, already noted for Typhobolel-
lus and now confirmed even more conclusively by Ergene. They
occupy a limited range in eastern Mexico, considerably removed from
the nearest known localities for more typical members of the family.

Ergene Chamberlin

Ergene Chamberlin, 1943, Bull. Univ. Utah, biol. ser., 8, no. 2, p. 4.

(Described as a new genus of Cambalopsidae, but compared with
Californian taxa later included in a new family Leioderidae by
Schubart).

Type species. — Ergene setosus [sic] Chamberlin, by original desig-
nation.

Diagnosis. — Generally similar to Typhloholellus but differing in
shape of the collum, which is more distinctly narrowed toward the
ends; in having the femur of the walking legs provided with a large,
falcate, retrorse dorsal spine; in having the metazonites moderately
setose ; and in the shape of the male genitalia, particularly the apically
notched sternum and spatulate telopodites of the coleopods, and
simple, laminate, unsegmented telopodites of the phallopods.

Ergene setosa Chamberlin. Figures 1-4.

Ergene setosus Chamberlin, 1943, Bull. Univ. Utah, biol. ser., 8, no. 2, p. 5,
figs. 3, 4.

Type material. — The species was originally stated to have been de-
scribed from two females taken at the intersection of "Highway No. 1
and Tropic of Cancer" about 19 miles south of Ciudad Victoria,

Figs. 1-4. Ergene setosa Chamberlin, structural details of holotype. 1. Head,
coUum, and 2nd segment, lateral aspect to show outline of collum. 2. Midbody leg.
3. Anterior gonopods (coleopods), aboral aspect. 4. Left posterior gonopod, aboral
aspect. Drawings made to different scales.

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32 FIELDIANA: ZOOLOGY, VOLUME 62

Tamaulipas, Mexico, by H. S. Dybas on June 17, 1941. Returned to
Field Museum in a vial bearing these data, and a label stating " 9
holotype" and " 9 paratype" in Chamberlin's hand\^Titing are a
complete adult male and the head of a second apparently conspecific
individual of unknown sex. The remainder of the body is perhaps still
in the Chamberlin collection at Salt Lake City. As no distinction
was made between the two ostensible "females," I herewith designate
the complete male specimen as a sort of "lecto-holotype." It has
been dissected and the gonopods and a midbody leg mounted on a
microscope slide.

Descripiion. — The holotype agrees fairly closely with the description given in
1969 for Typhloholellus whiteheadi, but it is considerably smaller — about 23 mm. in
length and about 1.0 mm. in diameter — and with 61 segments instead of 55.

Collum of the outline as shown in Figure 1, the anterior edge distinctly in-
dented in passing behind the mandibular stipes instead of almost perfectly straight
as in T. whiteheadi, and the lateral end therefore much narrower.

Body segments with prominent median constriction, longitudinally striated in
its deepest part. Most segments with moderately profuse setae on dorsal surfaces,
the setae of varying lengths and partially arranged in transverse series; prozonites
and lower sides glabrous. Segments otherwise as described for Typhloholellus.

Legs relatively short, scarcely extending laterad beyond sides of body, begin-
ning at about 23rd legpair each femur provided on the dorsal side with a large,
prominent, proximally recurved falcate spine (fig. 2). Coxa, prefemur, femur,
postfemur, and tibia each with a single apical ventral seta, tarsus with two setae;
prefemur, postfemur, tibia, and tarsus each with a lateral seta, tarsus also with
three dorsal setae, postfemur and tibia each with one dorsal seta. Tarsal claw rela-
tively large, with a small basal accessory spine. Anterior legs without modified
podomeres, their tarsal claws not reduced.

Coleopods of the form shown in Figure 3, the sternum produced medially and
apically notched; coxal endites prolonged, distally subacute, considerably exceed-
ing sternal apex; telopodites slender, spatulate, and apically rounded, equal in
length to coxal endite lobes. Coxa prolonged caudomesially and almost completely
separating telopodite from posterior extension of sternum.

Phallopods relatively simple, without evidence of complex sternal sclerites, no
trace of anatomical divisions; coxal region projecting mesad, telopodite region con-
nected at nearly a right angle, very thin and hyaline, of the outline shown in Fig-
ure 4; two small nearly transparent hyaHne projections from base of inner angle of
gonopod. Sternal apodeme long, slender, spirobolellid in form and location,
pivoted at midlength of coxal region.

Distribution. — This species is known so far only from the type
locality, between the east slope of the Sierra Madre Oriental and
Sierra Azul in southern Tamaulipas. This site is nearly 700 km.
northwest of the type locality of T. whiteheadi, and one is doubtless
justified in suspecting that a variety of these small blind millipeds
will be found in the intervening areas.

HOFFMAN: SPIROBOLOID MILLIPEDS 33

It is much to be hoped that collectors passing the type locality of
Ergene setosa will obtain additional material in order that a better
concept of the species can be formulated than is now possible from the
unique holotype. In particular, the gonopod complex requires a
careful study to verify the apparent absence of sternal elements from
the base of the phallopods.

REFERENCES

Chamberlin, R. V.

1943. On some genera and species of American millipeds. Bull. Univ. Utah,
biol. ser., 8, no. 2, pp. 1-20, figs. 1-38.

Hoffman, Richard L.

1969. Studies on spiroboloid millipeds. VII. A remarkable new genus and sub-
family of the Spirobolellidae from Vera Cruz, Mexico. Proc. Biol. Soc. Wash-
ington, 82, pp. 177-188, figs. 1-8.

UNIVERSITY OF ILLINOIS-URBAHA

590 5FI C001

FIELDIANA, ZOOLOGYSCHGO
62:1-51972