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Group Title: Bulletin of the Florida State Museum
Title: Some Mexican land snails of the family Urocoptidae
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Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00001530/00001
 Material Information
Title: Some Mexican land snails of the family Urocoptidae
Series Title: Bulletin of the Florida State Museum
Physical Description: 126-183 p. : illus., map. ; 23 cm.
Language: English
Creator: Thompson, Fred G ( Fred Gilbert ), 1934-
Publisher: University of Florida
Place of Publication: Gainesville
Publication Date: 1968
 Subjects
Subject: Urocoptidae   ( lcsh )
Gastropoda -- Mexico   ( lcsh )
Genre: bibliography   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 183.
General Note: Cover title.
General Note: Errata slip laid in.
Statement of Responsibility: by Fred G. Thompson.
 Record Information
Bibliographic ID: UF00001530
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA0840
notis - ABS5592
alephbibnum - 000299177
oclc - 00468975
lccn - a 68007811

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Full Text


BULLETIN

OF THE

FLORIDA STATE MUSEUM


BIOLOGICAL SCIENCES


Volume 12


Number 3


SOME MEXICAN LAND SNAILS OF THE
FAMILY UROCOPTIDAE

Fred G. Thompson


UNIVERSITY


OF FLORIDA


Gainesville
1968


fJ~
Io,


41.t







Numbers of the BULLETIN OF THE FLORIDA STATE MUSEUM are pub-
lished at irregular intervals. Volumes contain about 300 pages and are not
necessarily completed in any one calendar year.


Communications concerning purchase or exchange of the publication and all
manuscripts should be addressed to the Managing Editor of the Bulletin, Florida
State Museum, Seagle Building, Gainesville, Florida. 32601.


Published June 17, 1968


UNIVERSITY

OF FLORIDA

LIBRARIES










COLLEGE LIBRARY


Price for this issue $.85






SOME MEXICAN LAND SNAILS OF THE


FAMILY UROCOPTIDAE



FRED G. THOMPSON 1






SYNOPSIS: The genus Anisospira Strebel, 1880 is redefined on the basis of
anatomical characters and divided into two subgenera. Anisospira (sensu strict)
is restricted to include only the species from the Tehuantepec region. Trachycion
n. subgen., is proposed to include the remaining western Mexican species formerly
placed in Anisospira (s.s.). Dissotropis Bartsch, 1906 is redefined anatomically,
removed from subgeneric status within Anisospira, and recognized as a distinct
genus more closely related to Coelocentrum.
A. liebmanni (Pfeiffer) and A. dalli (Martens) are redefined, and their
anatomies are described for the first time. Cylirdrella hyalina Pfeiffer, A. orcutti
Dall, and Liocentrum wilmoti Bartsch are synonymized with A. liebmanni. New
subspecies and species include: A. d. strigens n. ssp. from near Tehuantepec,
A. (T.) hadromylla n. sp. from Coastal Michoacan, D. castaneum n. sp. from
Jalisco, and D. amplaxis n. sp. from Colima. The anatomy of D. castaneum is
described, providing a basis for relating Dissotropis to Coelocentrum.
Also included are the descriptions of the following: Coelocentrum tanydeira
n. sp. from San Luis Potosi; C. stenocion n. sp. from Guerrero; and C. tomacella
adelphion n. ssp., C. tyla n. sp., C. cataclines n. sp., and Eucolodium otoides
n. sp. all from Chiapas. Coelocentrum nelsoni Dall is redescribed and its type
locality restricted. The embryonic shells of C. pfefferi Dall, C. turis (Pfeiffer), C.
tomacella clava (Pfeiffer), and Eucolodium hegewischi Bartsch are also described.
Crossostephanus Dall, 1908 is synonymized with the subgenus Coelocentrum
Crosse and Fischer, 1872. Cylindrella ghiesbreghti (Pfeiffer), 1856 is synonymized
with Eucolodium decollatum (Nyst), 1841.








Fred G. Thompson is Interim Assistant Curator in Malacology at the Florida
State Museum. His current research includes systematics, zoogeography, and
ecology of neotropical land and freshwater mollusks.


Thompson, Fred G. 1968. Some Mexican Land Snails of the Family Urocop-
tidae. Bull. Florida State Mus., vol. 12, no. 3, pp. 125-183.








TIN FLORIDA STATE MUSEUM


INTRODUCTION
Many genera and species of Mexican land snails are known only
from the shells of a few specimens, and consequently their systematic
status still remains uncertain. Such is the case of the Mexican
Urocoptidae.
While conducting field studies in Mexico during 1964-1966 I
collected a considerable amount of material referable to the genera
Anisospira, Coelocentrum, and Eucolodium. Subsequent studies of
this material emphasized the unsatisfactory state of our knowledge
of these genera. The material has been sufficient to allow a review
of the genus Anisospira. Some systematic changes are proposed
within Coelocentrum, and descriptions of some new and poorly
known species are given for this genus and Eucolodium.


ACKNOWLEDGEMENTS
I wish to express my gratitude to the following individuals who have aided
me in this study: For the loan of type specimens in their charges I am in-
debted to Joseph P. E. Morrison, U. S. National Museum (USNM) and
Henry van der Schalie, Museum of Zoology, University of Michigan (UMMZ).
James A. Peters, U. S. National Museum, answered inquiries concerning the
type locality of Dissotropis henryi (Solem). Neil Chernoff, Dennis R. Paulson,
Wayne King, and my wife Donna M. Thompson assisted me in field work
in Mexico during 1965 and 1966. Field work was supported by the National
Institutes of Health research grant GM 12300.


Genus Anisospira Strebel
Anisospira Strebel, 1880; Beitr. Kennt. Fauna Mex. Land Sussw.-Conch., IV:
77.-Pilsbry, 1903; Man. Conch., 15: 24-25.-Solem, 1957; Not. Nat.,
(298): 4-5.
TYPE SPECIES: Cylindrella liebmanni Pfeiffer, 1846 (Pilsbry, 1903: 24).
Strebel (1880: 77) proposed Anisospira to include two Mexican
species of Eucolodium-like snails that have two spiral lamellae on
the axis of the last two whorls (Cylindrella liebmanni Pfeiffer and
C. hyalina Pfeiffer). He related the genus to Holospira and similar
genera that also have spiral axial lamellae. These lamellate genera he
placed in the family Cylindrellidae (=Urocoptidae s.s.). Eucolodium
and its allies he placed in the family Eucolodiidae (=Eucolodiinae,
Urocoptidae). Pfeffer (1887: 21) expanded the concept of Ani-
sospira to include A. strebeli Pfeffer, a species from southern Oaxaca
with a single lamella. Dall (1896: 353) treated Anisospira as a


Vol. 12






THOMPSON: MEXICAN LAND SNAILS


subgenus of Eucolodium, and described a fourth species, E. (A.)
strebeli Dall (=A. dalli Martens). Martens (1890: 255) recognized
Anisospira only as a section of Eucolodium and synonymized the
family Eucolodiidae with the Cylindrellidae. Pilsbry (1903: 24-30,
298-300) followed Strebel and Pfeffer in his treatment of Anisospira,
but emphasized its close relationship to Eucolodium. He included
in the genus Cylindrella recticosta Pfeiffer and A. r. townsendi
Pilsbry and Cockerell from Colima, and gave a partial description
of the anatomy of the latter form. He also recognized the subfamily
Eucolodiinae to include most of the Mexican Urocoptidae and the
Hispaniolan genus Archegocoptis. Later (1946: 111) he placed the
Holospira-like genera in the Holospirinae, thus restricting the Eu-
colodiinae to include Eucolodium, Coelocentrum, Anisospira and
Archegocoptis. Bartsch (1906: 113-115) described Dissotropis as a
subgenus of Anisospira, including two new species with a thin blade-
like axial lamella with many uniform serrate teeth along its edge.
After Dall (1910: 34) described A. orcutti (=A. liebmanni), no
additional contributions were made to the taxonomy of the genus
until Solem (1957: 3-10) reviewed the known taxa and described
A. (Dissotropis) henry. Solem was handicapped in his review by
the small amounts of material available at the time. Thus in nearly
90 years since its inception, the genus Anisospira has come to include
2 subgcnera, 9 species, and 1 subspecies based upon only a few
shells and a single anatomical examination.
The material before me, though not exhaustive, clarifies the
identity of five specific names, brings to light one new species and
one new subspecies of Anisospira, and necessitates the recognition
of a new subgenus within Anisospira. Dissotropis is removed as a
distinct genus, with the description of two new species. This review of
Anisospira and Dissotropis is based upon 414 adult shells, many juve-
nile shells, and anatomical material of three species and one sub-
species. I have examined the types of all species of Dissotropis.
DESCRIPTION Shell medium sized to large. Color varying from
brown to white. Cylindrical, fusiform, or pupiform in shape. De-
collate, 6.5-11.0 whorls remaining in adult shells. Apical whorls
frequently differentially reduced in size. Umbilicus imperforate.
Surface sculptured with vertical ribs or threads. Spiral sculpture
absent. Juvenile shell with distinct axial ribs that appear on 2nd
half of 1st whorl and continue on following whorls with no change
in intensity or spacing (fig. 1A); 3rd juvenile whorl 3.2-3.4 mm






BULLETIN FLORIDA STATE MUSEUM


wide, 5th and 6th whorls slightly constricted. Axis of juvenile shell
very thin, but hollow, straight; smooth, without accessory sculpture
or structures (fig. 1B). Axis in adult shell smooth, narrow, straight,
or weakly twisted, especially in the last whorl or two. Axis of last
2-5 whorls with one or two simple spiral lamellae that act as spiral
guides for movement of columellar retractor muscle.
The anatomy of the genus is described below under its two
subgenera, which share a few anatomical peculiarities, that charac-
terize the genus. The most important of these is the structure of
the central (rachidial) tooth of the radula. The central tooth has
a single enlarged mesocone; ectocones are absent or very rudimen-
tary. Other genera of the subfamily have well developed ectocones
on the central tooth.
Anisospira is characterized as a genus in the family Urocoptidae,
subfamily Eucolodiinac with a cylindrical, decollate shell, a narrow,
barely perforate axis bearing one or two simple spiral lamellae
confined to the lower whorls, but lacking other sculpture of the
axis at all stages of growth, and having a single, well defined cusp
on the central tooth of the radulae.










A







B



FIcUF. 1. Anisospira liebmanni (Pfr.) A.-Embryonic shell and B. juve-
nile whorls 6-14 showing simple axial structure (UF 19073). Scale=l mm.


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


COMPARISONS WITH OTHER MEXICAN GENERA
Eucolodium. This genus contains two subgenera, which are
distinguished on the basis of axial structure. In Oligostylus the
axis is simple, solid and straight or only slightly twisted. In Eu-
colodium (s.s.) the axis is solid, twisted, and bears a spiral lamella. The
lamella extends the length of the shell and is a flattened extension of
the twist in the axis. Anisospira differs in that the axis is narrowly
perforate, and the lamellae are confined to the lower whorls and
are thick deposits on the axis. In the bilamellate species of Anisospira
the upper lamella overlies the region of the axis where a twist
would occur, and is homologous in position to the axial lamella
of Eucolodium (s.s.). The lower lamella of the bilamellate species
and the single lamella in all other species of Anisospira lie just
above the floor of the whorl and have no relationship to that part
of the axis that would be involved in tortion if such existed. The
presence and position of this lower lamella is unique to Anisospira.
Eucolodium was previously thought to be unique within the
family because of the presence of a muscular plate produced by
the fused ocular retractors over the pharynx. This feature also occurs
in Anisospira (s.s.) (fig. 9). The extent of this character in other
generic groups of the subfamily is not known; it suggests a close
relationship between Oligostylus and Anisospira.
Coelocentrum. This genus includes several subgenera, all of
which are based upon the sculpture and modified shape of the axis.
All species bear some type of axial sculpture, including granules,
spines, ribs, or knobs. This sculpture is present on the axis of the
juvenile as well as of the adult shell. All species also have a con-
spicuously hollow axis. In some species groups and subgenera the
center of the axis has a spiral inflated bulge that may be greatly
extended and lamellar-shaped, but hollow (Crossostephanus Dall,
1908), or may even bear a lamella upon the bulge (Ptychocentrum
Bartsch, 1943). Anisospira differs from these groups by its completely
smooth, very narrowly perforate axis, and by the relative position
of the lamella with respect to other axial structures.
Solem (1957: 8) suggested that Ptychocentrum is transitional
between Coelocentrum and Eucolodium because it has an axial
lamella as does Eucolodium (s.s.) (and Anisospira) and a hollow axis
and axial ribs as does Coelocentrum. This suggestion assumes that
highly developed axial sculpture and well developed spiral lamella
are primitive characters, and that evolution from this primitive
condition involved the reduction or loss of both of these structures






BULLETIN FLORIDA STATE MUSEUM


in the respective genera. This is contrary to all other evidences,
which indicate that axial sculpture and lamella become more com-
plex in specialized groups, and that similar sculpture and lamella
have evolved independently in different species groups and genera
throughout the family. The well developed axial sculpture and
lamella of Ptychocentrum are specialized characters that were un-
doubtedly derived from the more generalized type of axis of Coelocen-
trum.
Dissotropis. -This genus is characterized by having a large
hollow axis, fine granular sculpture on the axis, and a high, blade-
like axial lamella with serrate teeth along its edge. A spiral axial
bulge is usually present above the lamella. The granular sculpture
is always present on the axis of the juvenile shell, but may be
much reduced in the adult shell.
Although the axial lamellae of Anisospira and Dissotropis are
similar in position, the lamellae have different relationships to ana-
tomical structures of the body and are analogous in function. In









'p
H[ H
C
OA
R











FicuRE 2. Diagrammatic cross-sections of A.-Anisospira liebmanni (Pfr.)
and B.-Anisospira d. dalli (Martens) through first whorl above aperture showing
relationship of axial lamella to free retractor muscles (COL, columellar retractor;
LP and RP, left and right pedal retractors; PHAR, pharyngeal retractor).


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


Anisospira the whole surface of the axis in the lower 4 whorls is
overlaid by the retractor muscles (fig. 2). The columellar retractor
has longitudinally incised grooves on its ventral surface, and the
lamellac fit into the grooves in such a way that they act as guides
for the spiral movement of the muscle into and out of the shell.
The rest of the viscera and the lung overlie the retractor muscles.
In Dissotropis all of the retractor muscles and viscera are situated
against the axis and lie above the axial lamella, which acts as a
supporting shelf for the visceral mass and maintains a uniformly
distended lung (fig. 12).
The different functions of the axial lamellae in the two genera
imply independent origins and evolutionary sequences of this struc-
ture in each genus. If Dissotropis evolved from Anisospira, the
retractor muscles and the viscera must have been translocated across
the lamella at some point in its evolution. No evidence for such
a "jump" exists, and simple mechanics argue against it. Dissotropis
probably evolved from Coelocentrum, which only requires that the
muscle and the viscera become localized around and above an
axial bulge; subsequent origin and development of an axial lamella
would retain the muscle and viscera in that position and maintain
a uniformly distended lung. Such a restriction of the muscle and
viscera has probably occurred along several independent lines in
Coelocentrum, as is suggested by the spiral series of enlarged axial
spines in the subgenus Ptychodonta and the lamellalike axial bulge
in other species groups and subgenera.
Subgenus Anisospira Strebel
Shell as in genus except: Sculpture consisting of very fine threads
or riblets; 4-7 thread-riblets per mm on antepenultimate whorl. Axis
with one or two spiral lamellae.
Sole undivided longitudinally. Pallial organs long. Lung four
whorls long. Kidney long, nearly semilunar, truncate at basal end.
Sigmurethrous. Heart large, about V1, length of kidney, and lying
near middle of kidney. Aorta continuous to mantle collar, without
secondary branches.
Salivary glands long, but not surrounding esophagus. Jaw simple,
solid, chitinous, with numerous very fine vertical striations on face.
1 13 12-15
Radular formula: C L M (101-124). Teeth lying in
1 2 2
nearly straight transverse rows. Cusps simple, acuminate. Central





BULLETIN FLORIDA STATE MUSEUM


tooth without any indication of ectocones. Lateral and marginal
teeth with one mesocone and one cctocone.
Reproductive system simple. Genital atrium moderately stout
or slender. Penis small, with a basal constriction and a relatively
large apical appendix which extends beyond epiphallus and is
terminated by penial retractor muscle. Inside of penis with eight
longitudinal folds and a fleshy pad around opening of epiphallus.
Epiphallus very large and long, originating from side of penis.
Spermathecal duct long and very large in diameter. Duct with a
slender delicate appendix that is about 2/3 length of duct and
originates from duct just above vagina.
Retractor muscles simple. Ocular retractors united over pharynx.
Right ocular retractor passing between genitalia and trophic viscera.
This subgenus contains two species and one subspecies, which are
distinguished by characteristics of the shells. Very few differences
occur in the anatomy of the three forms. They are distinguished
as follows:
1. Axis of shell with two spiral lamellae ...............A. liebmanni (Pfr.)
la. Axis of shell with a single spiral lanella ................... .....- (2)
2. Size larger, 27.2-37.0 mm long, 9.5-13.0 mm wide; last few whorls
not conspicuously constricted ............... A. d. dalli (Martens)
2a. Size small, 23.6-81.3 mm long, 8.3-10.0 Imm wide; last few whorls
more tightly coiled ........ .......................A. d. stringent n. ssp.
The two species are found in southeastern Oaxaca (fig. 3) where
they occur in numerous isolated colonies with many local variations.
The variations revolve about a few parameters of the shell that are fre-
quently repeated in colonies from widely separated areas, so that
most local varieties are difficult to characterize and distinguish from
one another. These variations are due to genetic peculiarities of the
colonies and are not environmentally induced. Throughout their
distribution both species are confined to limestone terrain and show
no tolerance of igneous rocks, lateritic soils, or alluvial plains. Hence
each colony is ecologically confined to the limestone exposure on
which it occurs. The variations in ground moisture and diversity of
plant formations may be nearly as great on a single limestone hill as
they may be among many small ranges of hills over a relatively large
area. Most limestone hills in the Tchuantepec region have more
ground moisture at their bases than near their tops, and the density
and diversity of plants is also greater near their bases. Snails collected
near the bottom of these hills where it is relatively cool, shaded, and
moist are not distinguishable from specimens collected at the tops of


Vol. 12






THOMPSON: MEXICAN LAND SNAILS


FIcunE 3. Geographic distribution in southwestern Mexico of species and
subspecies of Anisospira.

the same hills where it is relatively hot and dry. Yet colonies on
nearly identical limestone hills separated by only a few hundred yards
of alluvial plains or laterites are frequently as different from each
other as from remote colonies. These local variations can only be
interpreted as isolated genetic variations and not phenotypic re-
sponses to particular physical or biotic factors.

Anisospira liebmanni (Pfeiffer)
Cylindrella liebmanni Pfeiffer, 1846; Z. Malak.; 159.
Anisospira liebmanni (Pfeiffer), Strebel, 1880; Beitr. Kennt. Fauna Mex.
Land. Sussw.-Conch., IV: 79; pl. 5, figs. 12-13; p1. 14, fig. 2.-Pilsbry,
1903; Man. Conch. 15: 28-29; pl. 10, figs. 22-27; pl. 11, figs. 1-.-Solem,
1956; Not. Nat., (298): 5-6; pl. 1, fig. 5.
Cylindrella trochaeformis Sowerby, 1843 in Reeve; Conch. Icon., XX; pl. 9,
fig. 80 (young shell).
Cylindrella hyalina Pfeiffer, 1847, in Philippi; Abbild. u. Beschreib., 2: 47; pl. 2,
fig. 2.
Anisospira hyalina (Pfeiffer), Strebel, 1880; Beitr. Kennt. Fauna Mex. Land Sussw.-
Conch., IV: 19; pl. 13, fig. 16. -Pilsbry, 1903; Man. Conch., 15:26; pl.
10, figs. 18-21.
Eucolodium (Anisospira) orcutti Dall, 1910; Naut., 24: 34-36; -Dall, 1926;
Proc. U. S. Natl. Mus., 66 (17):17; pl. 23, figs. 8, 11.
Anisospira orcutti (Dall), Solem, 1957; Not. Nat., (298): 6; pl. 1.
Liocentrum wilmoti Bartsch, 1948; Proc. Biol. Soc. Wash., 88: 52, fig. 2.





134 BULLETIN FLORIDA STATE MUSEUM Vol. 12

SHELL.-(fig. 4A-C.) Moderately large, size variable. Decollate,
generally fusiform, but of variable shape; occasionally terete, or cy-
lindrical. Imperforate. Color various shades of light brown, occasional
populations almost white or pink. Shell solid and opaque though gen-
erally not thick walled, 6.8-11.0 whorls. Whorls nearly flat sided;
generally gradually increasing in size from apex to about middle of
shell, and thereafter remaining rather uniform in size or decreasing


FIGURE 4. Anisospira liebmanni (Pfr.). Shells of seven specimens from
Lagunas, Oaxaca (UF 19072) showing variation in shape and axial lamella.





THOMPSON: MEXICAN LAND SNAILS


slightly. Occasionally the initial few whorls may be nearly uniform in
size and then rapidly expand to the size of the lower spire. Suture
weakly impressed. Surface of whorls crossed by numerous fine, re-
curved, close, vertical threads that are continuous and equally de-
veloped between the sutures. Threads about 1/ or 1/3 as wide as
their intervals, 4-7 threads/mm. Base of last whorl with a low weak
spiral crest that may be obsolete in some specimens or populations.
Aperture free from preceding whorl, projected forward slightly.
Aperture nearly circular, with its greatest diameter lying in an oblique
direction from the upper outer corner to the basocolumellar comer.
Interior of aperture white. Aperture lying at 22-280 to axis of shell in
lateral profile. Lip slightly thickened and weakly expanded around
aperture. Axis narrow, about 1/12 diameter of shell, very narrowly
perforate. Axis with two spiral lamellae that are usually confined to
last 2 whorls. One lamella located just above floor of whorl; second
lamella located near middle of axis and may occur on low twist of
axis.
Embryonic whorls (fig. 1A) not clearly demarcated from follow-
ing whorls. First whorl protruding, gradually increasing in size through
3rd or 4th whorl which is 3.2-3.4 mm wide, next 2 or 3 whorls de-
creasing slightly in size. Following whorls regularly increasing in
size to point of decollation. Rate of growth indicates about 12-15
whorls lost above decollation point of adult shell. Initial half whorl
smooth; following whorl with vertical threads that become increasing-
ly strong and thereafter are nearly equally developed. Axis of juve-
nile shell simple and very narrow (fig. 1B).
Length of shell, 25.0-41.3 mm; diameter, 8.9-13.2 mm; aperture,
6.2-9.1 mm. Measurements representing four population samples are
given in table 1.

TABLE 1. MEASUnEMENTS or 131 SPECIMENS OF Anisospira liebmanni FROM 5
LOCALITIES.1
Locality No. Length Width Whorls Apert.
width
A 16.5 mi. SE of
El Cameron 12 30.0-36.7 9.9-10.5 7.1-9.3 7.0-8.9
B Lagunas 20 31.1-41.3 9.4-11.8 8.9-11.0 6.4-8.9
C Ojo de Agua 8 32.4-40.0 10.7-11.7 8.7-10.0 6.2-7.9
D 15.3 mi. NW Presa
Benito Juarez 84 25.0-33.0 8.9-10.6 6.8-10.2 6.2-7.9
E 7.0 mi. NW
Tehuantepec 7 32.8-37.0 11.4-13.2 7.7-9.1 7.9-9.1
LStandard deviations of measurements from populations A-D are graphically illustrated in
Fig. 4.






BULLETIN FLORIDA STATE MUSEUM


The shell is highly variable in many features, including size, num-
ber of whorls, shape, color, and axial development. The most notable
variations are in size and number of whorls. Each population tends
to be characterized by a particular size class of individuals, but con-
siderable variation occurs within any given population, and all meas-
urements between different populations overlap. Quantitative charac-
ters that were statistically analyzed for standard deviations are pre-
sented graphically (fig. 5). All characters show such broad overlap
that no statistical separation of the various populations can be made.
Shape is highly variable within most populations, and no particular
shape characterizes any single population. Color tends to be more
conservative within a population, but the differences between popula-
tions are slight, and the same color hues recur among geographically
remote populations as well as in various populations of A. dalli (Mar-
tens).


LENGTH OF SHELL
LENGTH OF SHELL


A

B


C

D
S IDT II 12
WIDTH OF SHELL


1J 14


L



A

B


C


D
APERTURE WIDTH
APERTURE WIDTH


FIcuRE 5. Standard deviations of three shell parameters of Anisospira lieb-
manni (Pfr.). Four population samples same as in table 1, A-D.


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


The development of the axial lamellae is also variable, and they
vary more within populations than between different popu-
lations (fig. I). In some specimens the upper lamella is very weak
and low, and both lamellac may be confined to only the last two
whorls. In other specimens both lamellae are very well developed and
extend to the third or fourth whorl.
The characteristics of four nominate species fall within the ob-
served variation: A. liebmanni (Pfeiffer), A. hyalina (Pfeiffer), A.
orcutti (Dall), and Liocentrum wilmoti Bartsch. These species were
recognized on the basis of size, number of whorls, color, and shape.
A. liebmanni is stout, has 7-8 whorls, is brownish-yellow in color and
has a strongly truncate upper spire in the adult shell. A. hyalina is
"about 12 mm" wide, has 10-13 whorls, is white or pinkish, and is
more nearly cylindrical. A. orcutti is large, is 10-14 mm wide, has 8.5-
10.5 whorls, is pale cinnamon-brown, and is nearly cylindrical. L.
wilmoti clearly was based upon an immature specimen of A. lieb-
manni.
The variation of the material examined encompasses the distinc-
tions of these species and does not permit separation by these or any
other characters. Even though some of the measurements of diameter
and number of whorls exceed the ranges of the material that I have
examined, the cited variations broadly overlap my measurements. Un-
doubtedly other populations exist that would expand the range of
measurements I have found in the material before me and encompass
these greater dimensions. The large number of whorls originally given
for A. hyalina (Pfeiffer, in Philippi, 1847: 47) may represent an unusual
specimen, or a specimen with two plugs in which decollation has
taken place only above the upper plug, as occasionally occurs.
ANATOMY.--Holopod; sole undivided longitudinally. Sides of foot
with a single series of low pilasters along sole. Sides and tail coarsely
pebbled. Dorsal surface of tail flattened posteriorly, rounded anterior-
ly; without caudal pore. Genital opening lying below and behind
right eye stalk.
Lung four whorls long. Pneumostome consisting of two slits in
mantle collar covered with a thick fleshy fold. Pneumostome lacking
accessory valves. Rectum and ureter discharging above pneumostome
through a single slit. Kidney (fig. 6) nearly semilunar in shape, but
blunt at basal end. Sigmurethrous. Primary ureter originating below
apex and tightly appressed to side of kidney. Secondary ureter at-
tached to rectum. Pericardium about 1t length of kidney. Auricle





BULLETIN FLORIDA STATE MUSEUM


ec. ureter


ureter




kidney .

FIGURE 6. Inner view of kidney and associated organs of Anisospira lieb-
manni (Pfr.). Scale = 1 mm.

1/2 again as large as ventricle. Aorta simple, continuous to mantle
collar, lying along base of whorl.
Jaw (fig. 7) arcuate, solid. Face smooth, with numerous very fine
vertical striations, but no ribs. Posterior margin with a reinforcing
ridge that parallels curvature of cutting edge. Ridge with a long,
broad cartilaginous flange that projects posteriorly.
1 13 12-14
Radular formula: C L -- M ---- (114-124). The teeth are
1 2 2
typical in shape and structure for the subfamily Eucolodiinae. Central
tooth with a large lanceolate mesocone and no ectocones. Laterals
with a large mesocone and a single small ectocone. Marginals with
a reduced mesocone and one ectocone.


FIGURE 7. Jaw of Anisospira liebmanni (Pfr.). Scale = 1 mm.


Vol. 12






THOMPSON: MEXICAN LAND SNAILS


Salivary glands long, flat, and diffuse posteriorly where they ex-
tend over sides and dorsal surface of the esophagus. Salivary ducts
long.
Genital atrium (fig. 8A, B) moderately long and stocky. Penis
small, slightly constricted above atrium, terminated apically by a
relatively large and conspicuous diverticulum. Penial retractor
muscle inserting on tip of diverticulum. Interior of penis below basal


FIGURE 8. Reproductive system of Anisospira liebmanni (Pfr.). A.-15.3 mi.
NW Presa Benito Juarez, Oaxaca. B.-Lagunas, Oaxaca. Sca.es = rnm.





BULLETIN FLORIDA STATE MUSEUM


constriction with 8-10 low longitudinal folds. A large fleshy pad lies
along the epiphallic side of upper penial cavity. Lumen of epiphallus
discharging through central slit in pad. Remainder of upper penial
wall with eight narrow longitudinal folds. Epiphallus originating
from side of penis. Interior of epiphallus with small conical elongate
fleshy tubercles about 0.1-0.2 mm wide and high. Epiphallus long,
well developed, almost as thick as penis, gradually diminishing in
size to the vas deferens. Vas deferens lightly attached to genital at-
rium by a few fine muscular fibers. Vagina long and relatively wide.
Inner wall of vagina with eight longitudinal folds that extend into
atrium. Spermathecal duct originating from vagina shortly above
atrium. Spermathecal duct very thick, basocolumellar in position.
Spermatheca impressed against prostate immediately below albumen
gland. Spermathecal duct with an appendix about 2/ as long as
duct; appendix very thin and delicate, and originating from duct im-
mediately above vagina. Uterus and prostate tightly appressed
throughout their lengths. Albumen gland moderately long, strongly
compressed or indented on each side by intestine and esophagus.
Hermaphroditic duct convoluted near albumen gland, entering gland
shortly above prostate. Ovotestis (not illustrated) with 6-8 lobes,
each lobe consisting of about 25-40 claviform papillac.
Penial retractor muscle originating from inner wall of lung about
one whorl above mantle collar and near lower left side. Length of
muscle variable in specimens from different localities, but part of
variation also due to degree of relaxation at time snail is preserved.
Columellar retractor muscle (fig. 9A) long, extending to apex of
shell and attaching to integument; distal end thick. Left pedal re-
tractor originating along left margin of columellar retractor in 4th
from last whorl. Pharyngeal retractor originating slightly distal to
this point and from dorsal surface of colnmellar retractor. Pharyngeal
retractor divided and subdivided distally into many narrow slips that
attach to base of pharynx. Right pedal retractor originating from
columellar retractor about 1/2 whorl distal to origin of pharyngeal re-
tractor. Right and left ocular retractors originating from correspond-
ing pedal retractors, and united dorsally over pharynx by a thin
muscular sheet. Right ocular retractor passing between the genitalia
and the remaining viscera, and giving off several small fibers that
attach to wall of vagina.
GEOGRAPHIC DISTRIBUTION.-(fig. 3.) This species is known from
several localities in the Tehuantepec region (Solem, 1957: 5-6) north-


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


LP -RP LP-L -RP

SPHAR.--

















-COL. -COL.



A B

FIcGnE 9. Diagrammatic illustrations of the free retractor muscles of A.-
Anisospira liehmanni (Pfr.) and B.-Anisospira d. dalli (Martens) demonstrating
differences in structure (COL, columellar retractor; LO and RO, left and right
ocular; PHAR, pharyngeal retractor; LP and RP, left and right pedal retractor).
Scale = 10 mm.

west to the area near Camaron, which is about halfway between
Tehuantepec and Oaxaca, Oaxaca. If Dall's original locality for A.
orcutti is correct (Dall, 1910: 34), the range extends considerably
farther west to the Rio Verde Valley in southwestern Oaxaca. Solem
(1957: 6) suggested that Dall's locality was incorrect, and that the
types of A. orcutti actually came from the town of Rio Verde near
Tehuantepec. This argument cannot be resolved without additional





BULLETIN FLORIDA STATE MUSEUM


ityi'cal n ShapzO and ntruo'ra for thc zubfrmily Eutolzdiirmoza rrtal
collections from the Rio Verde Valley, but Solem's suggestion is not
necessary to explain the identity or variation of various populations
in the Tehuantepec region.
The type locality for A. liebmanni was not given, but Strebel
(1880: 79) cited specimens as having come from Juchitan. This
city lies on a low alluvial plain many miles from limestone hills, but
is situated on the Rio Juchitan, which drains several low limestone
mountain ranges. Specimens reported from Juchitan probably were
collected elsewhere or were taken from stream drift along the Rio
Juchitan, for A. liebmanni has been collected alive only on limestone
terrain.
SPECIMENS EXAMINED.-OAXACA: 16.5 mi. SE El Camaron, 3200'
elevation (14); Ojo de Agua, 5.3 mi. E Entronque La Ventosa, 200'
(8): Lagunas (20); 15.3 mi. NW Presa Benito Juarez on Rio Tehuan-
tepec, 900' (86); 7.9 mi. NW Tehuantepec (7). All material in the
Florida State Museum collections.
RELATIONSHIPS.-This species is closely related to A. dalli (Mar-
tens), and may be only subspecifically distinct from it. All features of
color, size, whorl counts, sculpture, and shape broadly overlap or are
repeated in various populations of the two species. They can be
separated consistently only on the basis of the axial lamellae within
the last few whorls. All population samples that I have examined are
consistent in the number of lamellae present, although there may be
considerable variation in their development. A. liebmanni always has
two distinct lamellae, A. dalli only a single lamella. Some specimens
of A. dalli may have a twisted axis ii the last whorl which imparts
the appearance of a lamella, but it is clearly a twisted axis and not
a raised solid deposit on the axis. Pilsbry (1903: 27) suggested that
A. hyalina (=A. liebmanni) and A. dalli might be subspecifically
related. Solem (1957) followed Pilsbry's suggestion and united the
two, though he presented no data to justify this action. I have seen
no indication that these two species intergrade in axial structure.

Anisospira d. dalli (Martens)
Anisospira strebeli Dall, 1897; Proc. U. S. Natl. Mus., 19: 353; pl. 83, figs. 7,8.
(not Anisospira strebeli Pfeffer, 1887).
Eucolodium dalli Martens, 1901; Biol. Cent. Amer.: 633.
Anisospira dali (Martens), Pilsbry, 1903; Man: Conch., 15: 26-27; pl. 1, fig. 12;
pl. 10, figs. 28, 29.
Anisospira hyalina dalli (Martens), Solem, 1957; Not. Nat., (298): 5; pl. 1, fig. 6.


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


SHELL.-(fig. 10A-F.) Moderately large, fusiform with a subequal
or pinched apex, terete or cylindrical, imperforate, decollate. Color
various shades of light brown to nearly white; live shells generally
light tan. Walls solid but not thick. Whorls, 8.3-11.7, nearly flat
sided, only slightly arched between sutures. Generally initial 1-3
whorls conspicuously smaller than following whorls; next 2-3 whorls
rapidly increase to maximum size of adult shell; last 1-2 whorls de-
creasing slightly in diameter. Occasional shells may be nearly cy-
lindrical. Surface of whorls sculptured with numerous fine raised
vertical threads that are moderately arched posteriorly and uniform
and continuous between sutures; 4-7 threads/mm. Base of last whorl
with a very faint weak spiral ridge. Aperture free from preceding
whorls and projecting forward slightly, nearly circular or ovate,
its greatest diameter lying in an oblique direction. Peristome slightly
thickened and reflected around aperture. Interior of aperture and
peristome white or grayish white. Aperture lying at 24-350 to axis of
shell. Axis narrow, about 1/12 diameter of shell, very narrowly per-
forate, nearly straight throughout most of length of shell, but moder-
ately twisted in last whorl. Axis with a single spiral lamella that is
generally confined to the last 2 whorls. Lamella located on lower
part of axis just above floor of whorl, generally low, but may flare out
considerably in last whorl.
Embryonic and juvenile shell as in A. liebmanni. Rate of growth
indicates about 12-14 whorls lost above decollation point in adult
shell.
Length of shell, 27.2-37.0 mm; width of shell, 9.5-13.0 mm; aper-
ture diameter, 6.5-8.8 mm. Measurements of four populations and
their statistical analysis are given in table 2 and fig. 11A-C. As in
A. liebmanni this species is highly variable in size, number of whorls,

TABLE 2. MEASUREMENTS OF 180 SPECIMENS OF Anisospira dalli FROM 4 LOCAL-
ITIES.'
Locality No. Length Width Whorls Apert.
width
A 8.1 mi. NW 82 27.2-37.0 9.5-13.0 7.0-9.3 6.5-8.8
Tehuantepec
B 2.2 mi. NW 30 27.5-34.5 9.7-11.7 6.5-9.3 6.8-8.0
Mixtequilla
C 0.8 mi. N Presa 16 28.8-34.3 9.6-11.1 7.7-9.3 6.6-8.1
Benito Juarez
D stringens 52 23.6-31.3 8.3-10.0 6.9-9.6 5.5-7.1
LA-C represent populations of A. d. dalli; D represents the type series of A. d. stringens
n. asp. Standard deviations of these measurements are graphically illustrated in Fig. 11.




BULLETIN FLORIDA STATE MUSEUM


FIGURE 10. A-F.-Anisospira d. dalli (Martens), 8.1 mi. W Tehuantepec,
Oaxaca (UF 19074). G-L.-Anisospira d. stringens n. ssp. G.-Holotype. H-L.-
Paratypes, hill 0.4 mi. S Presa Benito Juarez, Oaxaca.


Vol. 12


kiv


*'"
r~p~p
-r~Bili





THOMPSON: MEXICAN LAND SNAILS


D
24 2i i28 0 12 34 36 31
LENGTH OF SHELL


A A

B B

C C

D D
9 10 II 12 13 14 4 7 1 9 IS
WIDTH OF SHELL APERTURE WIDTH

FIcGRE 11. Standard deviations of three shell parameters of Anisospira dalli.
Four population samples same as in table 2. A-C.-Anisospira d. dali (Martens).
D.-Anisospira d. stringens n. ssp.

shape and color, but to a lesser extent in the development of the
axial lamella. Practically the same statements made about these
characters in A. liebmanni also apply to this species.
Some colonies have rather striking aspects of shell size and ap-
pearance that tend to characterize them. In some instances the varia-
tion may be subspecifically significant; one such population is so
described below.
ANAToMY.-This species is very similar in anatomical characters
to A. liebmanni, and only the more important features are described.
1 13 14-15
Radular formula: C L -- M ---- (101-106).
1 2 2
Reproductive system (fig. 12A) as in A. liebmanni except: Genital
atrium more slender. Interior of penis below basal constriction with
a heavy longitudinal fold. Fleshy pad along epiphallic wall of penis
well developed (fig. 12B); 8-9 narrow fleshy folds on remainder of


1968






BULLETIN FLORIDA STATE MUSEUM


FIGURE 12. A.-Reproductive system of Anisospira d. dalli, 8.1 mi. W
Tehuantepec, Oaxaca. B.-Inner view of penis showing fleshy pad with central
slit opening from lumen of epiphallus. Scale = 1 mm.

penis wall. Interior of epiphallus with numerous small oblique folds
and papillae that tend to be more elongate than in A. liebmanni.
Lumen of vagina below spermathecal duct with seven heavy folds
that extend into the atrium. Lumen of uterus above spermathecal
duct with many low folds arranged in oblique series.
Retractor muscles (fig. 9B): Left pedal retractor originating on
dorsal surface of pharyngeal retractor slightly distal to origin of latter
muscle. Pharyngeal retractor divided distally into six bands that at-
tach to base of pharynx.
GEOGRAPHIC DISTRIBUTION.-(fig. 3.) This species has been col-
lected from a relatively small area of limestone hills and mountains
west and north of Tehuantepec. Previous locality records from Huilo-
tepec (Dall, 1897: 353, type locality) and Salina Cruz and La Ventosa


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


(Solem, 1957: 5) are questionable. As with the former species A.
dalli is confined to limestone terrain. Huilotepec lies on a low alluvial
plain along the Rio Tehuantepec and is far from any limestone out-
crops. The only nearby hills are a low range of granitic mountains a
few miles to the east. The type specimens may well have been col-
lected from river drift carried downstream from farther north where
this species does occur. Salina Cruz and La Ventosa both lie on the
coast and the only stone in the immediate area is a soft crumbly
granite. Specimens reported from these two localities may have been
collected from beach drift or from farther west where limestones do
occur.
SPECIMENS EXAMINED.-OAXACA: hill 8.1 mi. NW Tehuantepec,
450' (82); hill 2.2 mi. NW Mixtequilla, 400' (30); 0.8 mi. N Presa
Benito Juarez on Rio Tehuantepec, 500' (16). All material in the
Florida State Museum.
RELATIONSHIPS.-The relationship of this species to A. liebmanni
has been discussed under that species. Its affinities to the following
form are discussed under that subspecies.
Anisospira dalli stringens new subspecies
SHELL.-(fig. 10G-L.) Relatively small, fusiform or terete; apex
occasionally pinched. Decollate. Compactly coiled; initial 1-2 whorls
small; following 2 whorls rapidly increasing in size; remaining whorls
nearly equal in size, decreasing slightly near base; last whorl notice-
ably constricted. Umbilicus imperforate. Axial puncture very small
or closed. Light brown to light tan in color, dull. Shell firm but not
thick; 6.9-9.6 whorls remaining in adult shell. Suture moderately im-
pressed; whorls nearly flat sided, only slightly arched between sutures.
Surface sculptured with numerous fine, close, oblique, recurved
vertical threads that are about 1/4 as wide as their intervals; 5-7
threads/mm. Last whorl with a nearly obsolete basal crest. Aperture
nearly circular; its greatest diameter lying at an oblique angle. Aper-
ture free from last whorl and projected slightly forward, lying at 26-
340 to axis of shell in lateral profile. Peristome only slightly thickened
and reflected. Interior of aperture and peristome white. Axis narrow,
straight, increasing slightly in diameter in lower whorls, about 1/12-
1/15 diameter of shell, very narrowly perforate. Axis with a spiral
lamella confined to last two whorls; lamella located on axis just above
floor of whorl.
Embryonic whorls not demarcated from following whorls, rapidly
increasing in size to about 3rd whorl; following 3 whorls decreasing




BULLETIN FLORIDA STATE MUSEUM


slightly in size; remaining whorls gradually increasing in size to point
where adult shell becomes decollate; 3rd whorl 2.8 mm wide. Rate
of growth indicates about 14-15 whorls lost from adult shell above
point of decollation. Initial 3/4 whorl smooth. Following whorl with
fine axial threads that become increasingly strong and thereafter are
nearly uniform in size and spacing.
Measurements of holotype: length, 27.8 mm; width, 9.3 mm; aper-
ture diameter, 6.0 mm; 8.5 whorls remaining (fig. 10G).
Measurements of paratypes: length, 23.6-31.3 mm; width, 8.3-10.0
mm; aperture diameter, 5.5-7.1 mm.
TYPE LOCALITY.-OAXACA hill about 0.4 mi. S of the Presa Benito
Juarez on the Rio Tehuantepec, about 18 mi. NW Tehuantepec.
HOLOTYPE: UF 19079; collected 15 July 1966 by Fred G. Thompson.
PARATYPES: UF 19080 (24), 19081 (3 juveniles), 19082 (23), 19083
(1 juvenile); Museo de Historia Natural de la Ciudad de Mexico (5).
The type locality lies in a narrow ravine on the north side of a hill
paralleling the road to the dam. The bottom of the ravine is wooded
with a sparse submesic forest, while the sides of the ravine and the
top of the hill are xeric. Snails were found in the ravine and on the
hillsides irrespective of the vegetational differences. Their distribu-
tions did not reflect any apparent preference for ground moisture.
DISTRIBUTION.-(fig. 3.) This subspecies is known only from the
type locality and is probably restricted to the immediate vicinity.
Typical A. d. dalli occurs on the immediately opposite side of the
Rio Tehuantepec, as it does only a few miles east on both sides of the
river, near Mixtequilla.
RELATIONSHPS.-A. d. stringens is closely related to A. d. dalli from
which it differs in its generally more terete or fusiform shape, its smal-
ler size, and its more constricted last whorl. The differences between
the two subspecies overlap, and only about 75 per cent separation
is possible with size characters.
ETYMOLOGY.-The name stringens is derived from the Latin for
constricted and refers to the nature of the last whorl.
Trachycion new subgenus
GENOTYPE: Anisospira recticosta townsendi Pilsbry and Cockerell, 1903.
Shell generally as in genus. Sculpture consisting of coarse ribs
that are uniformly developed and evenly spaced over surface of shell;
3-5 ribs per mm on antepenultimate whorl. Juvenile shell unknown.


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


Radula with 27-1-28 rows. Central tooth barely tricuspid. Meso-
cone broad, lanceolate; ectocones very small and appearing only as
lateral tubercles at base of mesocone. Lateral and marginal teeth
bicuspid with a mesocone and a small ectocone.
Genital atrium very short (?), Penis very short and globose, with
a broad, flat apex. Epiphallus originating from apex of penis. Penial
retractor muscle inserting on apex of penis around origin of epiphal-
lus. Inner wall of penis with a very short, high pilaster. Epiphallus
about 4 times as long as penis, well differentiated, but not approach-
ing size of penis. Spermathecal duct very long, but not noticeably
swollen below spermatheca. Spermathecal appendix unknown. (Ana-
tomical data from Pilsbry, 1903: 298-299).
Trachycion is found from southern Oaxaca northwest at least to
Colima (fig. 3) and contains three species and one subspecies. The
forms are represented by very few specimens, and little is known
about local distributions and variation. The new species described
below is the only new material that has been reported since Solem
(1957) reviewed the genus.
ETYMOLOGY.-The name Trachycion is derived from the Greek
trachys + cion and refers to the rough pill j or ai s. The gender of
the name is neuter.
Key to the Species of Trachycion
1. Sculpture consisting of coarse vertical ribs; 2-3 ribs/mm........................ 2
la. Sculpture consisting of fine vertical ribs; 4-5 ribs/mm......................
2. Axial lamella thin and wide. Peristome conspicuously thickened.
Color white. Umbilicus imperforate...............-...........A. hadromylla n. sp.
2a. Axial lamella rounded, no higher than wide. Peristome moderately
thickened. Flesh-colored. Umbilicus rimate ............ A. strebeli (Pfeffer)
3. Whorls narrow, middle whorl of adult shell 4 mm wide...........................
A. r. tounsendi (Pils. and Cock.)
3a. Whorls wider, middle whorl of adult shell 5 mm wide...........................
A. r. recticosta (Pfeiffer)
Anisospira recticosta recticosta (Pfeiffer)
Cylindrella recticosta Pfeiffer, 1847, in Philippi; Abbild. u. Beschreib.; 2: 48;
pl. 2, fig. 3.
Eucolodium recticosta (Pfeiffer), Crosse and Fischer, 1872; Miss. Scient. Mex.,
Moll., 1: 386; pl. 14, figs. 12-12b.-Pilsbry, 1903; Man. Conch., 15:
16; pl. 3, figs. 21-23.
Anisospira r. recticosta (Pfeiffer), Pilsbry, 1903: Man. Conch., 15: 299.
The type locality of this species is not known. It has been record-
ed from Cualata, Colima, but those specimens probably belong to
the following subspecies (Pilsbry, 1903: 299).


1968




BULLETIN FLORIDA STATE MUSEUM


Anisospira recticosta townsendi Pilsbry and Cockerell
Anisospira recticosta var. townsendi Pilsbry and Cockerell, in Pilsbry, 1903; Man.
Conch., 15: 298-300; pL 63, figs. 51-55 (anatomy); vol. 16, pl. 11,
fig. 85, 86 (shell).
This subspecies is known only from the holotype (ANSP 84385),
which came from Cualata, Colima (fig. 3).
Anisospira strebeli Pfeffer
Anisospira strebeli Pfeffer, 1887; Verh. Ver. Naturw., Hamburg: 21.-Pilsbry,
1903: Man. Conch., 15: 29-30; pl. 10, figs. 30-34; pl. 11, fig. 4.-
Solem, 1957; Not. Nat., (298): 5; pl. 1, figs. 3, 4.
Eucolodium strebeli (Pfeffer), Martens, 1900; Biol. Cent. Amer., 265; pl. 16,
figs. 31-34.
This species is known only from Cerro de Plumas (type locality),
and Puerto Angel, Oaxaca (fig. 3).
Anisospira hadromylla new species
SHELL.-(fig. 13A-D.) Large; cylindric-terete; solid, opaque; dull
white. Periostracum absent. Apical puncture absent. Umbilicus im-
perforate. Base of last whorl rounded, marked with a weak, nearly
obsolete basal keel. Decollate, adult shell consisting of 6.6-8.1 whorls.
Suture impressed, whorls moderately arched between sutures. Apical
whorl 0.52-0.59 times diameter of shell. Initial 1-2 whorls uniform in
size, following 2-3 whorls rapidly increasing in size, rest of shell nearly
cylindrical. Aperture broadly elliptical or broadly ovate, about as
high as wide, usually free from preceding whorl, but may be adnate
in some specimens. Aperture slightly oblique in lateral profile.
Peristome conspicuously thickened and reflected around aperture.


FIGURE 13. Anisospira hadromylla n. sp. A.-Holotype. B-D.-Paratypes.


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


Interior of aperture and peristome shiny white. Apical plug coarsely
granular. Whorls with numerous moderately coarse, weakly recurved
ribs, slightly stronger near bottom of whorl than top. Ribs about 1/2
as wide as their intervals and equally spaced over surface of shell;
99-104 ribs on antepenultimate whorl. Axis solid, smooth, very
slightly sigmoid; increasing in diameter in lower whorls, about 1 mm
wide in last 2 whorls. Axis with a smooth flat spiral lamella confined
to the last 1 1/2 whorls. Lamella located about 1/4 of distance above
floor of whorl. Width of lamella less than diameter of axis. Lamella
visible within aperture as a columellar bulge.
Juvenile shell unknown.
Measurements of the type: length, 42.0 mm; width, 13.8 mm;
aperture height, 11.5 mm; aperture width, 10.8 mm; diameter of
apical whorl, 7.6 mm; 7.6 whorls remaining.
Measurements of the paratypes: length, 34.6-42.2 mm; width,
13.2-14.8 mm; aperture height, 9.6-10.8 mm; aperture width, 9.9-10.9
mm.
TYPE LOCALrTY.-MICHOACAN: 10.0 mi. SE San Vicente; 200' alti-
tude. HOLOTYPE: UF 19055; collected 31 May 1966 by Fred G.
Thompson.
PARATYPES: UF 19056 (2), UF 19057 (5); same locality as the type.
The type locality is in a small range of limestone hills along the
Pacific coast (fig. 3). The range is a small extension of the Sierra de
Coalcoman and lies about 10 miles southeast of the Rio Coahuayana,
which forms the boundary between the states of Michoacan and
Colima. The snails were found in debris and mulch around limestone
blocks in a submesic deciduous forest.
REMARKS.-A. hadromylla is distinguished from other species of
Trachycion by its stout, heavily ribbed white shell and its thick peris-
tome. The only other forms of Anisospira known from western Mexi-
co are A. r. recticosta (Pfeiffer) and A. r. townsendi Pilsbry and Cock-
erell, both of which occur in adjacent regions of Colima. A. had-
romylla differs from recticosta and townsendi by its larger size, coarse
sculpture, and thick peristome. A. hadromylla resembles A. strebeli
(Pfeiffer) from southern Oaxaca in size and in sculpture, but differs
from that species in its white color, its thick peristome, and its im-
perforate umbilicus. A. strebeli is a large flesh colored species with a
moderately thickened peristome and a rimate shell. It also has a
thick, low axial lamella, whereas the axial lamella of A. hadromylla
is flat and blade-like.





BULLETIN FLORIDA STATE MUSEUM


ETYMOLOCY.-The name hadromylla is derived from the Greek
hadros, meaning thick, and myllon, meaning lip, and refers to the
nature of the peristome.
Dissotropis Bartsch
Dissotropis Bartsch, 1906; Proc. U. S. Natl. Mus., 31: 113.-Solem, 1957; Not.
Nat., (298): 7.
Type species by original designation: Anisospira (Dissotropis) stearnsi Bartsch,
1906.
Shell medium to large cylindric-terete, decollate. Umbilicus im-
perforate. Axis hollow, apical puncture narrow; 7.8-10.4 whorls in
adult shell. Sculpture consisting of uniformly spaced vertical ribs
or threads. Axis with a wide serrate spiral lamella confined to the
last 5 whorls of the adult shell. Spiral lamella acting as supporting
shelf for viscera and maintaining a uniformly distended lung (fig. 14).
Axis also with granular and spiny sculpture along central zone of
axis or on axial bulge. Granular sculpture most strongly developed in


FIGURE 14. Dissotropis castaneum n. sp. Diagrammatic cross-section through
2nd whorl above aperture showing relationship of axial lamella to soft anatomy
(COL, columellar retractor; ESOPH, esophagus; LP and RP, left and right pedal
retractor; PHAR, pharyngeal retractor).


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


juvenile shell (fig. 16B, C), and may be much reduced in adult shell.
Embryonic whorls not distinct from following whorls. First 1.0-1.5
whorls smooth. Following whorls with vertical ribs as in adult shell.
Sole of foot bipartite, with a medium longitudinal groove. Pallial
organs long. Lung 4.5 whorls long. Kidney semilunar in shape.
Sigmurethrous, primary ureter convoluted. Heart 12 as long as kid-
ney. Pericardium separated from middle of kidney by a gap equal
to width of heart. Aorta simple, continuous to mantle collar.
Salivary gland surrounding esophagus. Jaw simple, solid, chitinous,
with many moderate vertical ribs on face. Radular formula:
1 22
C L+M -- (84-85). Teeth arranged in slightly arched trans-
3 2
verse rows. Cusps simple, acuminate. Central tooth with a large
mesocone and a small ectocone on each side. Lateral and marginal
teeth with one large mesocone and a smaller ectocone each.
Reproductive system relatively complex for family. Genital atrium
moderately stout. Penis large, bulbous, with two large fleshy internal
pads. Epiphallus enlarged, arising from distal end of penis, with
six longitudinal fleshy folds. Vas deferens small, partially imbedded
in muscular wall of vagina. Spermathecal duct long, without ac-
cessory appendix. Vagina large, with a stout retractor muscle origi-
nating from pharyngeal retractor muscle. Talon and carrefour visible.
Retractor muscles simple. Ocular retractors not united over phar-
ynx. Right ocular retractor muscle passing between genitalia and
trophic viscera. Pharyngeal retractor with a stout ventral band that
attaches to vagina, and a secondary band running from vaginal re-
tractor to left pedal retractor.
Dissotropis is most closely related to Coelocentrum. The two
genera are anatomically alike in features of the reproductive system,
particularly the absence of a spermathecal appendix and of a mus-
cular plate formed by the ocular retractors over the pharynx. It is
difficult to make further comparisons with Coelocentrum because so
little is known about the anatomy of its many species. The anatomi-
cal peculiarities of Dissotropis suggest the two genera are not closely
related. These peculiarities include the presence of a vaginal retractor
attached to the pharyngeal retractor muscle, the bulbous penis with
two opposing internal fleshy pads, and the vas deferens imbedded in
the wall of the vagina. The shell is also peculiar in the presence of
a long wide serrate axial lamella. In other respects the shell resembles




BULLETIN FLORIDA STATE MUSEUM


that of Coelocentrum in having a hollow axis with granular sculpture.
The relationship between Dissotropis and Schizopyla cannot be
determined at present. The two groups are alike in having a thin
axial lamella, but differ in that Schizopyla has two additional lamellae
in the 3rd whorl, one on the pallial wall and one on the outer wall.
Schizopyla is anatomically unknown and is retained as a subgenus of
Coelocentrum where it was first placed (Pilsbry, 1939: 27).
Dissotropis was described as a subgenus of Anisospira because of
the presence of spiral lamellae in both genera. The location of the
lamellae is a secondary feature, for they have different functions in
the two genera. Their anatomies differ in many important aspects
and indicate relationships with other genera.
Dissotropis contains five known species. Two of these (D. stearnsi
and D. blandi) are known only from specimens in the Bland Collec-
tion in the USNM with the dubious locality of "near Mazatlan"
(Sinaloa). Recent field work near Mazatlan has failed to reveal this
genus in that region. A single specimen of Anisospira dalli (USNM
58055a) was originally catalogued with the type of D. blandi (USNM
58055b). A. dalli is known only from the Tehuantepec region. Mani-
festly either specimens and data have been mixed, or early collectors
used the locality "near Mazatlan" indiscriminately for specimens
without data. Recently Solem (1957: 7-8) described D. henryi from
coastal Michoacan, and provided the first reliable locality record for
Dissotropis. The two new species described below extend the known
range of the genus to adjacent regions of Colima and Jalisco.
Key to the Species of Dissotropis
1. Axis relatively wide, about 0.20 times diameter of shell at widest point,
straight sided or with only a very slight spiral bulge.............................. 2
la. Axis relatively narrow, about 0.08-0.10 times diameter of shell. Axis with
a noticeable raised spiral bulge that may even cause the axis to appear
twisted .............. .............. ......--- ....-...... ..... ..-- .................. 4
2. Sculpture consisting of prominent sinuous axial ribs ........................
D. henry (Solem)
2a. Sculpture consisting of fine axial threads ..................................... 3
3. Axial lamella very wide. Axis with fine granular sculpture present along
center of axis in upper whorls in adult shell. Axis with irregular, oblique
white streaks ....................................................... D. amplaxis n. sp.
3a. Axial lamella narrower. Axis smooth or with nearly obsolete granules in
uppermost whorls. Axis without oblique white streaks ....................
D. blandi (Bartsch)
4. Color brown. Sculpture consisting of prominent ribs. Axis of adult shell
with fine granular sculpture along turgid bulge ............ D. castaneum n. sp.


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THOMPSON: MEXICAN LAND SNAILS


4a. Color white. Sculpture consisting of fine axial threads. Axis of adult shell
smooth or with fine granular sculpture nearly obsolete and confined to
uppermost whorls .................. ........................... .. D. stearnsi (Bartsch)
Dissotropis stearnsi (Bartsch)
Anisospira (Dissotropis) steamsi Bartsch, 1906; Proc. U. S. Natl. Mus., 31: 113-
114; pl. 3, fig. 1.
TYPE LOCALrrY.-"near Mazatlan". HOLOTYPE: USNM 58055b.
Dissotropis henryi (Solem)
Anisospira (Dissotropis) henryi Solem, 1957; Not. Nat., (298): 7-8; pl. 1, fig.
11-14.
TYPE LOCALITY.-MICHOACAN: La Placity (Sulatillo), Sierra de Coal-
coman. HOLOTYPE: UMMZ 185499.
Dissotropis castaneum new species
SHELL.-(fig. 15.) Medium sized, decollate, cylindric-terete, shiny.
Light brown in color. Generally thin and fragile but some specimens
may be solid; commonly transparent. Umbilicus imperforate. Axial
puncture very small. Initial whorl 0.51-0.55 times diameter of shell,
7.3-9.1 whorls remaining. Apical 3-4 whorls rapidly increasing in
size to adult shell; following whorls of nearly equal size; last whorl
slightly narrower. Suture moderately impressed. Whorls moderately
















FIGURE 15. Dissotropis castaneum n. sp. A.-Holotype. B-D.-Paratypes.

arched between sutures. Aperture free from preceding whorl; pro-
jected slightly forward; slightly oblique in lateral profile. Aperture
nearly circular, 0.96-1.07 times as high as wide. Peristome slightly or
moderately thickened and reflected. Interior of aperture dusky white





BULLETIN FLORIDA STATE MUSEUM


or brownish. Columella visible within aperture. Sculpture consisting
of oblique, low, vertical ribs that are about as wide as their intervals.
Ribs weakly arched; about 4-5 ribs/mm; 120-150 ribs on antepenulti-
mate whorl. Basal keel on last whorl very weak or absent. Axis hol-
low, straight but with a low spiral bulge, increasing slightly in di-
ameter to last whorl where it becomes constricted closed. Axis about
1/6-1/7 diameter of shell. Axis with a thin wide spiral lamella on last
5 whorls just below spiral bulge on axis. Edge of lamella with about
25 low, serrate teeth per whorl. Spiral bulge on axis with numerous
small spines and granules that continue from juvenile shell.
Embryonic whorls (fig. 16A) not distinct from following whorls.
First 3 whorls rapidly increasing in size, 3rd whorl 2.9-3.1 mm wide,
5th and 6th whorls constricted, following whorls gradually increasing
in size to decollation point. First whorl smooth, next whorl with low
vertical ribs that become increasingly developed, following whorls























B C
FIGURE 16. Juvenile shells of two species of Dissotropis. A.-D. castaneum
n. sp., embryonic and early juvenile whorls showing sculpture (UF 19760).
B.-D. castaneum n. sp., juvenile whorls 7-16 showing twisted, spiny axis (UF
19760). C.-D. amplaxis n. sp., juvenile whorls 7-14 showing axis (UF 19766).
Scale = 1 nun.


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


through adult shell uniformly sculptured, with low vertical riblets.
Axis (fig. 16B) hollow, with a strong spiral bulge, which has many
large spines that point forward and continue on bulge into adult
shell. Rate of growth indicates about 14-16 whorls are lost above
decollation point in adult shell.
Measurements of holotype: length, 34.2 mm; width, 10.5 mm;
aperture height, 7.6 mm; aperture width, 7.6 mm; 8.2 whorls remain-
ing.
Measurements of paratypcs: length, 29.6-34.8 mm; width, 9.7-11.8
mm; aperture height, 6.9-7.7 mm; aperture width, 6.8-7.7 mm.
ANATOMY.-Holopod. Sole bipartite, with a medium longitudinal
furrow. Sides of sole with a single row of fleshy vertical pillasters.
Dorsal surface of foot and side of body pebbled. Dorsal surface of
tail flattened posteriorly, moderately crested anteriorly. Dorsal
caudal pore absent. Genital opening below and behind right eye
stalk.
Lung 4.5 whorls long. Kidney (fig. 18C) sigmurethrous, semi-
lunar, rounded anteriorly, truncate posteriorly, flat and thin. Heart
about 1/2 length of kidney, separated from center of kidney by a
space equal to its own width. Ventricle about 1/2 length of auricle.
Aorta simple, unbranched, extending to mantle collar. Primary ure-
ter with many loops loosely attached to kidney. Secondary ureter
closely attached to intestine.
Salivary ducts entering dorsal surface of pharynx (fig. 17B).
Salivary glands long, completely surrounding esophagus as a moder-
ately thick spongy mass.
Jaw (fig. 17A) solid, arcuate, amber colored, with a moderately
long, broad cartilaginous projection posteriorly. Face of jaw with
many moderately coarse vertical ribs.
1 22
Radula (2 examined): Radular formula C L+M -- (84-85).
3 2
The central tooth has a large mesocone and two small but well devel-
oped ectocones. The lateral and marginal teeth are not distinguish-
able from each other and each has a large mesocone and a smaller
ectocone. The teeth occur in slightly arched transverse rows.
Genitalia (fig. 18A): Genital atrium moderately stout and moder-
ately long. Penis large, bulbous, solid. Penial lumen (fig. 18B) with
two large fleshy pads that lie on opposite sides of cavity. Epiphallus
originating from top of penis. Lumen of epiphallus entering penis





BULLETIN FLORIDA STATE MUSEUM


pharynx


-:{'. :,3hOr r .,






B

FIGURE 17. Dissotropis castaneum n. sp. A.-Jaw. B.-Esophagus and associ-
ated organs. Scale = 1 mm.

between fleshy pads. Epiphallus well developed, long, abruptly con-
stricted at vas deferens. Interior of epiphallus with six low longi-
tudinal folds. Penial retractor muscles moderately stout, originating
on center of inner wall of lung about one whorl behind mantle col-
lar and inserting on top of penis near origin of epiphallus. Vas de-
ferens imbedded in wall of vagina shortly above genital atrium and
emerging again above and opposite origin of spermathecal duct.
Vagina stout, with a broad muscular band that inserts near top of
vagina and originates from ventral surface of pharyngeal retractor
muscle. Lumen of vagina with about 12 low longitudinal folds that
occasionally anastomose. Spermathecal duct long, moderately stout,
lying along basocolumellar side of prostate. Spermathecal duct with-
out an appendix. Spermatheca elongate, slightly enlarged, lying near
base of albumen gland. Uterus and prostate long, tightly attached to
each other. Carrefour visible in oviduct below albumen gland. Talon
exposed at base of hermaphroditic duct. Albumen gland slender,
relatively short, thin, fragile.
Columellar retractor muscle (fig. 19) extending 5 whorls into shell
and attached to integument, thin but broad distally. Pharyngeal re-
tractor originating from dorsal surface of columellar retractor just
below its origin. Right pedal retractor originating from right ventral
side of pharyngeal retractor. Left pedal retractor originating from
left ventral side of pharyngeal retractor distal to origin of right


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


uterus
/- /-- ,. p tate

{ *'* V '' :


albumin gland


FIGmUE 18. Anatomy of Dissotropis castaneum n. sp. A.-Reproductive sys-
tem. B.-Interior of penis showing fleshy pad on opposite side of penial lumen.
C.-Inner view of kidney and associated organs. Scale = 1 mm.

pedal retractor. Right and left ocular retractors originating from cor-
responding pedal retractors, not united over pharynx. Right ocular
retractor passing between trophic viscera and genitalia. Pharyngeal
retractor thick and stout, attached to end of pharynx with one stout
central dorsal band and numerous small thin ventral bands and
slips. A stout muscular band originates from ventral surface of pha-





BULLETIN FLORIDA STATE MUSEUM


RO


RP


FIGURE 19. Diagram of free retractor muscles of Dissotropis castaneum n.
sp. (COL, columellar retractor; LO and RO, left and right ocular retractor; LP
and RP, left and right pedal retractors; PHAR, pharyngeal retractor; VAG,
vaginal retractor).

ryngeal retractor and attaches to side of vagina; a smaller band con-
nects this muscle to left pedal retractor.
TYPE LOCALITY. JALISCO: limestone sink 6.0 mi. SW and 6.5
mi. E Pihaumo, 2200' altitude. HOLOTYPE: UF 19758; collected 3
August 1966 by Fred G. Thompson. PARATYPES: UF 19761 (14
adults), UF 19759 (1 adult), UF 19762 (10 adults), UF 19763 (5
juveniles), UF 19760 (6 juveniles), Museo de Historia Natural de la
Ciudad de Mexico (4 adults). Same locality as the holotype.
The type locality lies at the base of a large limestone sinkhole on
the south side of a road that goes from a mine to Federal Highway
110. The base of the sink is covered with blocks of limestone and
talus and has a submesic forest. Snails were found under talus,
debris, and mulch along the walls of the sink.
RELATIONSHIPS.-This species is most similar to D. amplaxis, which
it resembles in its granular and spiny sculpture on the axial bulge
of the adult shell. Other species of Dissotropis also have this axial
sculpture, but it is much finer and noticeable only on the upper
whorls.
D. castaneum differs from all other species by its brown color and
its axis. The raised spiral bulge gives the axis a twisted appearance,
and in this way it resembles D. stearnsi (Bartsch). D. stearnsi lacks


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


distinct granulation on the middle axis, it is nearly white in color,
and the ribs on the surface of the whorls are much finer. D. cas-
taneum differs from D. amplaxis by its narrower axis bearing a spiral
axial bulge, its narrower axial lamella, its brown color, and its much
stronger ribs on the whorls.
ETYMOLOcY.-The name castaneum, Latin for chestnut, refers to
the color of the snail's shell.
Dissotropis amplaxis new species
SHELL (fig. 20A-D). Large, cylindric-terete, decollate, shiny.
Light grayish brown in color. Thin and fragile. Umbilicus imper-
forate. Apical puncture very minute but open. 9.4-10.4 whorls re-
maining. Suture distinct but shallow; whorls only slightly arched be-
tween sutures. Initial whorl small, 0.44-0.47 times diameter of shell,
following 3-4 whorls gradually increasing in size to adult shell, re-
maining whorls nearly equal in size, decreasing slightly near base.
















FIGURE 20. Dissotropis amplaxis n. sp. A-B.-Holotype. C-D.-Paratypes.

Aperture free from preceding whorl and projecting slightly forward,
oblique in lateral profile. Aperture broadly ovate, 0.94-1.00 times as
high as wide. Peristome moderately thickened and moderately re-
flected. Columella visible within aperture. Sculpture consisting of
numerous low, smooth recurved vertical riblets that are about 1/2 as
wide as their intervals. Riblets nearly equally spaced over surface of
shell; 137-157 riblets on antepenultimate whorl. Basal keel absent on
last whorl or only very vaguely indicated. Axis hollow, wide, grad-




BULLETIN FLORIDA STATE MUSEUM


ually increasing in width through penultimate whorl and becoming
narrowly constricted in last whorl. Axis at its widest point about 1/
width of shell. Axis with a spiral lamella and minute granular sculp-
ture. Spiral lamella located slightly below middle of axis in last 5
whorls; low and smooth at first, but very wide in last 3 whorls where
it bears about 20 large serrate teeth per whorl. Axis with a very low
spiral bulge just above lamella. Bulge in earlier whorls with numer-
ous small granular tubercles and spines that continue from juvenile
shell to 4th from last whorl of adult shell. Axis marked with irregular
oblique white streaks.
Embryonic whorls not distinct from following whorls. First 3
whorls gradually increasing in size, 3rd whorl about 2.5 mm wide, 5th
and 6th whorls slightly constricted, following whorls gradually in-
creasing in size to adult shell. First 1.5 whorls smooth, following
half whorl with vertical threads that become increasingly strong and
intense across whorl, thereafter riblets nearly equally developed and
spaced over surface of shell. Axis of juvenile shell (fig. 16C) hollow,
twisted. Spiral axial bulge with small granules and spines that point
forward and continue on axis into adult shell.
Measurements of holotype: length, 37.0 mm; width, 12.5 mm;
aperture height, 8.4 mm; aperture width, 8.6 mm; 10.1 whorls.
Measurements of paratypes: length, 31.8-38.2 mm; width, 11.4-
11.7 mm; aperture height, 7.7-8.2 mm; aperture width, 7.7-8.7 mm.
Little variation other than size occurs among the four adult speci-
mens comprising the type lot.
TYPE LOCALITY. COLIMA: 1.9 mi. NE Tecolapa; 700' altitude.
Specimens were found under limestone slabs on a xeric hillside along
the northwest side of the highway from Colima to Tecoman. HOLO-
TYPE: UF 19764; collected 1 June 1966 by Fred G. Thompson. PARA-
TYPES: UF 19765 (3 adults), UF 19766 (3 juveniles); same data as
the holotype.
RELATIONSHIPs.-This species is most similar to D. castaneum. It
is distinguished by its fine sculpture consisting of very fine low rib-
lets, its wide straight axis, its very wide axial lamella, and its light
color. It is distinguished from other species by its granular axial
sculpture, as well as other characters outlined in the key.
ETYMOLOGY. The name amplaxis is derived from the Latin
ampliare, to enlarge, and axis, and refers to the enlarged axis of this
species.


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


Dissotropis blandi (Bartsch)
Anisospira (Dissotropis) blandi Bartsch, 1906; Proc. U. S. Natl. Mus., 31: 114-
115; pl. 3, fig. 3.
TYPE LOCALITY.-"near Mazatlan." HOLOTYPE: USNM 58055.
Coelocentrum
Subgenus Coelocentrum Crosse and Fischer
Coelocentrum Crosse and Fischer, 1872; J. Conchyl., 20: 302. Type species:
Cylindrella turris Pfeiffer, 1856.
Crossostephanus Dall, 1908; Proc. U. S. Natl. Mus., 85: 177. Type species:
Coelocentrum palmeri Dall and Bartsch, 1908.
Crossostephanus has been considered as a distinct and isolated
subgenus since it was originally proposed. Species described in this
paper indicate that recognition of this subgenus as a separate entity
from Coelocentrum (s.s.) is not justified. Coelocentrum (s.s.) has been
defined by previous authors as a subgenus with a simple hollow axis
that bears oblique axial ribs. The axis could be simple and tubular
or could possess a low spiral swelling, and the ribs could be com-
plete, broken, or modified into oblique rows of low tubercles. Crosso-
stephanus was defined as possessing a turgid spiral axial ridge with
numerous short cord-like ribs (Dall, 1908: 177). The axial modifi-
cations that occur in C. tomacella (Morelet), C. tyla n. sp., and C.
cataclines n. sp. bridge the distinctions between the two subgenera.
The short cord-like ribs on the axial swelling of Crossostephanus are
of no more than specific value, as this character is only a matter of
degree and occurs independently in C. palmeri Dall and Bartsch and
C. tyla n. sp.
Coelocentrum (s.s.) is redefined as those species of Coelocentrum
(s.l.) with a hollow axis which may bear a hollow spiral swelling. The
swelling may project far into the lumen of the whorls, and may be
compressed and lamellar in shape. The axis also bears oblique axial
ribs that extend from the top of the whorl to the periphery of the
swelling when it is present, and the ribs may be broken or modified
into oblique rows of small tubercles, elongate cords, or knobs. Other
internal barriers are absent. The axis of the embryonic shell is hol-
low and bears sculpture similar to that of the upper whorls of the
adult shell. Coelocentrum (s.s.) includes the following described
species.
1. C. anconai Bartsch, 1948
2. C. anomalum Strebel, 1880
3. C. arctispira (Pfeiffer), 1960


1968




164 BULLETIN FLORIDA STATE MUSEUM Vol. 12

3a. C. a. estephaniae Pilsbry, 1903
4. C. cataclines new species
5. C. dispar Pilsbry, 1903
6. C. fistulare (Morelet), 1849
7. C. gigas Martens, 1897
8. C. hinkleyi Pilsbry, 1909
9. C. huertae Bartsch, 1947
10. C. lundersi (Pfeiffer), 1859
11. C. nelsoni Dall, 1896
12. C. palmeri Dall and Bartsch, 1908
13. C. pfefferi Dall, 1896
14. C. pittieri Bartsch, 1906
14a. C. p. guatemalensis Bartsch, 1906
15. C. stenocion new species
16. C. tanydeira new species
17. C. tomacella (Morelet), 1849 and varieties
18. C. turris (Pfeiffer), 1856
19. C. tyla new species
Although characters for natural species groups and subgenera
have been difficult to define, features of the embryonic and juvenile
shells are of value. These characters vary little within species groups
or genera, whereas adult shells may differ radically. Our knowledge
of juvenile shells is still too meager to allow the synthesis of a natural
arrangement of species groups. Future collectors should make a con-
certed effort to collect juvenile shells whenever possible.

Coelocentrum tanydeira new species
SHELL.-(fig. 21.) Small, light brown, shiny; decollate, with 15.1-
16.4 whorls remaining. Cylindric-terete in shape; initial whorl 0.48-
0.58 times diameter of shell, reaching its greatest diameter at about
the 6th or 7th whorl, or about 1/3 of distance from top of spire. Below
this point shell nearly uniform in width until 3rd or 4th whorl from
aperture, at which point the shell tapers inward. Aperture located
on a long rounded neck that protrudes forward and slightly down-
ward for a distance about equal to diameter of last whorl (2-3 mm).
Neck rounded and without basal keel. Aperture small, nearly circular,
slightly wider than long and tending to be flattened dorsally; peri-
stome thickened and reflected all around aperture; peristome and
interior of aperture white. Umbilicus imperforate, axial puncture
generally open, occasionally closed. Whorls slightly convex. Su-




1968 THOMPSON: MEXICAN LAND SNAILS 165


FIGURE 21. Coelocentrum tanydeira n. sp. A, C.-Holotype (UF 19040). B.
-Paratype (UF 19042).

ture consisting of a narrow impressed groove accentuated by a sharp
narrow spiral thread that runs along top of whorls by suture. Whorls
sculptured with strong recurved axial ribs about 1/4 diameter of inter-
vals; ribs uniform in size throughout their length, continuous across
whorls; 61-78 ribs on 4th from last whorl; ribs nearly uniformly
spaced throughout length of adult shell. Upper ends of ribs con-
nected by chord thread that parallels suture, spiral chord lying just
below ends of ribs so that ends protrude slightly into suture, spiral
chord terminating at base of neck. Axis hollow throughout its length,
about 1/-2% diameter of shell; axial pillar concave within each whorl
and bearing about 15-20 oblique riblets per whorl; riblets occurring
throughout length of axis to penultimate whorl, confined to upper 3/4
of pillar within each whorl; riblets slightly thickened at their lower
ends and may bear or be broken into many small conical tubercles.
Embryonic shell (fig. 22A) consisting of about 2.5 small, rounded,
button-like smooth whorls 1.2 mm wide. Later whorls gradually in-
creasing in size. Sculpture beginning on 3rd whorl as small uniformly
spaced triangular knobs along suture and becoming progressively





BULLETIN FLORIDA STATE MUSEUM


longer so that at about the 9th whorl vertical riblets are continuous
across surface of whorls.
Measurements of holotype: length of shell, 27.3 mm; width of
shell, 6.1 mm; aperture height, 3.4 mm; aperture width, 3.5 mm; 16.0
whorls remaining; diameter of first whorl, 3.1 mm.
Measurements of paratypes: length of shell, 25.5-29.8 mm; width


C.0,
C


A


D-J


F
Imm.


FIGURE 22. Juvenile whorls of various species of Coelocentrum and Eucolo-
dium. A.-C. tanydeira n. sp., paratype (UF 19041). B.-C. tomacella adelphion
n. ssp., paratype (UF 19046). C.-C. turris (Pfeiffer) (UF 19035). D.-E.
hegewischi (Bartsch) (UF 19063). E.-C. stenocion n. sp., paratype (UF 19062).
F.-C. pfefferi Dall (UF 19054). G.-C. nelsoni Dall (UF 19030).


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


of shell, 6.0-6.4 mm; aperture height, 3.2-3.4 mm; aperture width,
3.5-3.6 mm.
TYPE LOCALITY.-SAN Luis POTOSI: 11.4 mi. by road E Xilitla;
1100'. The type locality lies in a deep ravine on a limestone hillside
covered by a moist tropical forest that has been converted into a
coffee grove. Snails were found in leaf mulch on the hillside near the
bases of limestone boulders. HOLOTYPE: UF 19040, collected 20 May
1965 by Fred G. Thompson. PARATYPES: UF 19042 (7), 19041 (juve-
nile shell with embryonic whorls), same data as the holotype.
REMARKS.-C. tanydeira is distinct within the subgenus Coelocen-
trum because of its long projecting rounded neck, its strong, relatively
sparse costulate sculpture with a connecting subsutural spiral thread,
its small size, and its relatively large number of whorls. Nearly all
other species within the subgenus have a much shorter neck or have
the aperture juxtapose to the preceding whorl, have finer and more
numerous riblets, lack a subsutural spiral thread, have a larger shell
diameter, and fewer whorls in shells of about the same length.
C. tanydeira is most similar to C. hinkleyi Pilsbry, which is the
nearest geographically of the related species. Both species are simi-
lar in shape and sculpture, but C. hinkleyi is longer (35-41 mm), has
a greater diameter (8-9 mm), fewer whorls (11-15.5), a narrower
axial pillar (about 1/4 the diameter of the shell), and weaker sculp-
ture on the pillar (the axial riblets being reduced to elongate gran-
ules or light streaks) (Pilsbry, 1909: 138).
ETYMOLOGY.-The name tanydeira is derived from the Greek tan-
yein, meaning stretched out, and deire, meaning neck.

Coelocentrum stenocion new species
SHELL.-(fig. 23.) Medium sized, slender, light brown, dull, luster-
less. Decollate, with 8.7-11.6 whorls remaining. Shell moderately
thick, opaque. Nearly cylindric in shape; apex slightly terete, but
lower whorls nearly uniform in width. Initial whorl 0.61-0.73 times
diameter of lower shell; following 4-5 whorls gradually increasing in
size, and thereafter shell nearly uniform in diameter. Aperture free
from and projecting slightly beyond previous whorl, slightly oblique.
Neck rounded, with a very weak basal keel. Aperture nearly circular,
weakly angulate at the parietocolumellar and parietolabial corners;
aperture about as high as wide. Peristome slightly thickened and re-
flected all around aperture. Aperture and peristome shiny, dirty white.


1968




BULLETIN FLORIDA STATE MUSEUM


FIGuRE 23. Coelocentrum stenocion n. sp. A, C.-Holotype (UF 19060).
B, D.-Paratypes (UF 19061).

Umbilicus imperforate. Axial puncture very narrow. Whorls weakly
convex. Suture weakly impressed. Whorls sculptured with weak re-
curved ribs that are continuous and nearly uniform between sutures;
nearly equally developed and spaced over whole surface of adult
shell. Ribs about 1 width of their interspaces, about 73-88 ribs on
antepenultimate whorl. Axis hollow throughout its length, about 1/8
diameter of shell. Axial pillar straight-sided within each whorl, in-
creasing slightly in diameter in upper whorls, but uniformly wide in
lower whorls. Axis sculptured with oblique irregular, rugose ribs;
about 15-20 ribs per whorl; ribs frequently broken and knobby.
Embryonic shell (fig. 22E) consisting of 4.3-4.4 whorls; 3rd whorl
2.0-3.0 mm wide, next 2 whorls decreasing in size to form a distinct
neck from rest of shell, following whorls regularly increasing in size
to adult shell. First embryonic whorl smooth, following whorls sculp-
tured with fine ribs that begin as weak threads along suture and be-
come progressively stronger through the 4th and 5th whorl, where
they become fully developed for rest of shell. Rate of growth of juve-
nile shell indicates about 16 whorls occur above point where adult
shell becomes decollate.


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


Measurements of holotype: length, 39.0 mm; diameter, 8.1 mm;
aperture height, 6.0 mm; aperture width, 6.3 mm; diameter of first
whorl, 5.9 mm; 11.3 whorls remaining.
Measurements of paratypes: length, 31.2-39.1 mm; diameter, 8.2-
8.6 mm; aperture height, 5.9-6.0 mm; aperture width, 6.0 mm.
TYPE LOCALITY.-GUERRERO: limestone cliff 5.6 mi. NNE El Ocoti-
to; 2900' elevation. HOLOTYPE: UF 19060; collected 28 June 1966 by
Fred G. Thompson. PARATYPES: UF 19061 (4), UF 19062 (7 juve-
nile fragments); same data as the holotype.
Specimens were found in debris and mulch at the base of a rug-
ged limestone ledge. The base of the ledge and the immediate
vicinity were covered with a dense scrub forest.
REMARKS.-This species is not closely related to any other known
species from the Pacific slopes of Mexico, although adults resemble
C. tanydeira and C. hinkleyi from San Louis Potosi. It differs from
both of these species by its weak sculpture and its narrow axial pil-
lar with more rugose oblique axial riblets. Its embryonic whorls are
very different in size and sculpture, and suggest relationships with
C. pfefferi and some other large species.
ETYMOLOGY. The name stenocion is derived from the Greek
stenos, meaning narrow, and cion, meaning pillar, and refers to the
narrow axis of this species.

Coelocentrum tomacella adelphion new subspecies
SHELL.-(fig. 24.) Medium sized, dark brown, dull. Cylindric-
conical, thin but solid, opaque, decollate, 12.0-14.1 whorls remaining.
Width of initial whorl 0.54-0.63 times diameter of shell; whorls slowly
increasing in diameter; greatest width of shell attained at antepenulti-
mate whorl, below which point the shell decreases slightly in di-
ameter. Aperture free from preceding whorl, extended forward on
a short neck that is about 1/5-1/6 diameter of last whorl; aperture
0.89-0.96 times as high as wide, quadrangular or subtriangular in
shape, basal and outer margins frequently rounded. Peristome
strongly reflected, about 1.46-1.68 times width of neck; not notice-
ably thickened. Interior of aperture and peristome white. Umbilicus
very narrowly but consistently perforate. Last whorl with a weak
crest around base extending to peristome. Axial perforation open,
about 1/4 diameter of first whorl. Surface of shell covered with fine
but distinct recurved axial threads that extend unbroken across the





BULLETIN FLORIDA STATE MUSEUM


surface of the whorls; 87-106 threads on antepenultimate whorl;
threads nearly equally spaced over whole surface of shell, strongest
and most distinct on early whorls, rather weak on last whorl; threads
about 1/2-2/ width of intervals. Interspaces with very fine, sparse


FIGURE 24. Coelocentrum tomacella adelphion n. ssp.
19052). C.-Paratype (UF 19046).


A, B.-Holotype (UF


granules. Spiral sculpture absent. Axis hollow, about 1/3 or slightly
less diameter of shell, weakly expanded below middle of whorl and
moderately constricted below swelling. Axis with about 15-20 ob-
lique, low, thin, occasionally serrate ribs that extend from roof of
whorl to apex of swelling where they increase slightly in size. Axis
smooth below swelling.
Embryonic whorls (fig. 22B) not demarcated from later whorls.
First 5 whorls button shaped, narrow, very convex at periphery; 2nd
whorl slightly wider than adjacent whorls, 1.8 mm in diameter; 6th
and later whorls regularly increasing in size. First 2 embryonic
whorls smooth, following whorls with weak axial crenulations ap-
pearing along sutures, becoming progressively more distinct and
longer, and by 8th or 9th whorl forming threads that extend across
surface of whorls. Rate of growth of juvenile shell indicates that


Vol. 12





THOMPSON: MEXICAN LAND SNAILS


about 20 whorls occur above point where adult shell becomes decol-
late.
Measurements of holotype: length, 28.2 mm; diameter, 7.8 mm;
aperture height, 4.8 mm; aperture width, 5.0 mm; diameter of first
whorl, 4.4 mm; 12.6 whorls remaining.
Measurements of paratypes: length, 27.3-31.1 mm; diameter,
7.7-8.0 mm; aperture height, 4.6-5.0 mm; aperture width, 5.0-5.4 mm.
TYPE LOCALITY.-CHIAPAS: ravine 4.5 mi. N Jitotol; 5400' elevation.
HOLOTYPE: UF 19052; collected 16 July 1965 by Fred G. Thompson.
PARATYPES: UF 19046 (9, including 1 juvenile), Museo de Historia
Natural de la Ciudad de Mexico (1); same data as the holotype.
Specimens were found in debris at the base of a soft limestone
ledge. The flora in the ravine consisted mostly of mesic vegetation
because of seepage and ground moisture. The hills along the ravine
were dry with sparse growths of oaks and pine.
REMARKS.-This subspecies is in nearly all respects a diminutive
version of C. t. tomacella (Morelet), which differs in having a larger
shell (length, 33-37 mm; width, 9.5-10 mm), a rimate umbilicus, and
aperture that is higher than wide. These differences also distinguish
C. fistulare (Morelet) from C. t. adelphion.
Northern Chiapas and Tabasco are inhabited by many popula-
tions of C. tomacella most of which have their own characteristics.
This infraspecific variation includes C. t. clava (Pfeiffer), C. t. rufes-
cens Martens, C. t. attenuata (Pfeiffer) and probably C. fistulare
(Morelet), as well as C. t. adelphion. Until most of these populations
have been studied, taxonomic recognition of subspecific variations is
of questionable value. Recognition of C. t. adelphion is prompted by
the necessity to refer to it in anatomical studies.
ETYMOLOGY.-The name adelphion is derived from the Greek
adflphos, meaning brother, and refers to the close relationship be-
tween this subspecies and C. t. tomacella.

Coelocentrum tomacella clava (Pfeiffer)
TABASCO: 1.0 mi. E Teapa (UMMZ 121093 [6]).
The sculpture of the embryonic shell is in most respects similar
to that of C. t. adelphion. The embryonic shell differs only in that
the second whorl is 1.7 mm wide. Rate of growth of juvenile shell
indicates about 17-18 whorls are lost above decollation point of
adult shell.





BULLETIN FLORIDA STATE MUSEUM


Coelocentrum turris (Pfeiffer)
CmAPAS: 8.2 mi. S Solusuchiapa, 1600' elevation (UF 19038 [1]).
TABAsco: hill 9.2 mi. S Tacotalpa (UF 19037 [1]); mogotes 2.4-2.6 mi. E
Teapa (UF 19034 [6], 19035 [12], 19036 [5]).
The embryonic shell (fig. 22C) is similar to C. t. adelphion. Em-
bryonic whorls not demarcated from later whorls. First 6 whorls
strongly arched, button-like, suture deeply impressed, following
whorls becoming progessively flatter; 3rd whorl wider than adjacent
whorls, 2.1 mm wide; 4th-6th whorls constricted, following whorls
regularly increasing in size. First embryonic whorl smooth, following
whorls sculptured with fine axial threads that begin on 2nd whorl as
short striations below suture and become progressively longer and
stronger until about the 9th whorl where they form fine, continuous
thread-riblets. Rate of increase in size indicates about 16-17 whorls
are lost above decollation point of adult shell.

Coelocentrum pfefferi Dall
Coelocentrum pfefferi Dall, 1896; Proc. U. S. Natl. Mus., 19: 352; pl. 33, figs. 1,
2.-Pilsbry, 1903; Man. Conch., Ser. 11, 15; 34-35; pl. 11, figs. 5, 6
(copied from Dall).-Bartsch, 1906; Proc. U. S. Natl. Mus., 31: 116.
CHIAPAs: 14.6 mi. E Cintalapa, 2000' (UF 19054 [16]).
Dalls (1896: 352) description satisfactorily characterizes the
adult shell of this species, but measurements of the specimens from
near Cintalapa add significantly to the dimensions given by Dall (l.c.)
and Bartsch (1906: 116) for the type specimens (USNM 107367).


FiGunR 25. A-D.-Coelocentrum pfefferi Dall (UF 19054).


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


Measurements for the specimens from near Cintalapa are: length,
38.7-49.4 mm; width, 14.1-16.8 mm; aperture height, 9.7-11.9 mm;
aperture width, 9.0-11.0 mm; 7.5-9.4 whorls remaining in decollate
shells; diameter of apical whorl 8.2-10.2 mm. Adult shells are
illustrated in fig. 25.
Embryonic shell (fig. 22F) consisting of 3.5 whorls, which rapidly
increase in size through the 3rd whorl; 3rd whorl about 2.8 mm wide,
next 2 whorls slightly reduced in size, remaining whorls gradually
increasing in size through adult shell. Suture weakly impressed.
First 1 1/2 embryonic whorls smooth, following whorl sculptured with
fine radial threads that first appear very weakly along upper suture,
but soon extend completely across the whorl. Threads become in-
creasingly distinct through 5th or 6th whorl where they form riblets.
These continue equally developed through about the 15th whorl;
thereafter they become much lower and less distinct; 18.8 juvenile
whorls formed above decollation point of adult shell in only complete
specimen examined.
The type specimens E. W. Nelson collected were stated to have
come from Ocozocoautla, Chiapas (Dall, 1896: 352). They could
actually have come from the immediate vicinity of the new locality
cited above. Nelson visited this region on his way east from Rancho
San Ricardo to Ocozocoautla and made varied ecological observations
there (Goldman, 1951: 106-107). Nelson frequently labelled speci-
mens collected on the way to a locality as having come from that
locality (Goldman, 1951). The specimens from 14.6 mi. E Cintalapa
are so similar to the type specimens as to suggest that they came
from the same population.

Coelocentrum nelsoni Dall
Coelocentrum nelsoni Dall, 1896; Proc. U. S. Natl. Mus., 19:352; pl. 33, figs.
5-6.-Pilsbry, 1903; Man. Conch., Ser. 11, 15:35; pl. 11, figs. 8-9.
Dall's description of this species is misleading. It is based only on
the holotype and ignores the variation shown by other specimens
from the type series. He also describes important features of the
species inaccurately and fails to mention others. Material recently
collected could only be identified questionably with Dall's description.
Thus it is advisable to redescribe the species from the holotype
(USNM 107368), paratypes (USNM 185902 [5]), and recent speci-
mens.
SHELL.-(fig. 26.) Large, stocky; cylindric-terete. Light grayish-





BULLETIN FLORIDA STATE MUSEUM


F.,
-y


4..


adLZgi


- *-I-


FIrGRE 26. Coelocentrum nelsoni Dall. A.-Chiapas, 3.0 mi. SSE Tuxtla
Gutierrez, 2700' elevation (UF 19030). B-D.-Chiapas, 8.0 mi. N. Tuxtla Gutier-
rez, 3800' elevation (UF 19027). E.-Chiapas, 7.3 mi. SE Tuxtla Gutierrez,
2700' elevation (UF 19029).


Vol. 12


L





TIIOMPSON: MEXICAN LAND SNAILS


brown or brown; dull, lusterless; thickness of shell highly variable;
opaque. Decollate, 6.6-10.0 whorls remaining. Width of initial whorl
0.44-0.68 times diameter of shell. Early whorls of adult shell rapidly
increasing in diameter until about the 4th-5th from last whorl, below
which point they are nearly uniform in size. Suture shallow, but
sharply incised. Aperture free from preceding whorl and projected
slightly forward; aperture 1.07-1.23 times as high as wide, subtrape-
zoidal in shape, basal and outer angle tending to be weakly rounded.
Peristome usually only slightly expanded; generally only moderately
thickened, although conspicuously so in the type. Interior of aperture
and peristome white. Umbilicus rimate or very narrowly and
obliquely perforate. Last whorl weakly angulate around the base.
Axial perforation very narrow, about 1/10-1/12 diameter of top
whorl. Surface of shell with weak, low, recurved axial threads that
are slightly stronger near sutures; threads nearly uniformly spaced
over most of shell, more crowded on narrow early whorl; 102-144
threads on penultimate whorl; threads about equal to half the width
of their interspaces. Periostracum with many very thin, low, ir-
regular spiral threads that are frequently lost through wear; spiral
threads most conspicuous near lower suture of whorls and usually
broken between axial threads. Axis hollow, about 1} diameter of shell;
with a low spiral swelling lying just above lower partition within
etach wbor), and about 25-30 weak low, objigue, axial threads that
may be broken into rows of small conical granules.
Embryonic whorls (fig. 22G) not demarcated from later whorls.
First 4 whorls large, dome-shaped, with a weakly impressed suture;
3rd whorl 3.2-3.4 mm in diameter; 5th-6th whorls slightly constricted.
First 1.5 embryonic whorls smooth; succeeding whorls with fine,
regularly spaced axial riblets that begin near the upper suture and
become progressively longer and stronger until by the 2nd whorl
they are continuous across the surface. Rate of growth of juvenile
shell indicates about 20-22 whorls are lost above decollation point of
adult shell.
Length, 42.9-53.9 mm; diameter, 16.1-19.1 mm; aperture height,
10.7-13.2 mm; aperture width, 9.3-11.0 mm.
SPECIMENS EXAMINED.-CHIAPAS: Tuxtla Gutierrez holotypee and
paratypes); 8.0 mi. N Tuxtla Gutierrez, 3800' elevation (UF 19027
[5], UF 19028 [5]); 7.3 mi. SE Tuxtla Guticrrez, 2700' elevation (UF
19029 [5 ); 3.0 mi. SSE Tuxtla Gutierrez, 2700' elevation (UF 19030
[28]).


1968




176 BULLETIN FLORIDA STATE MUSEUM Vol. 12

REmARKs.-Coelocentrum nelsoni is unique within the genus be-
cause of its raised spiral sculpture. It is also readily distinguished by
its large size, stocky shape, and simple axial sculpture.
The type series E. W. Nelson collected was stated to have come
from Tuxtla Gutierrez, Chiapas (Dall, 1896: 352). Actually the type
series probably came from about 3 miles south of Tuxtla Gutierrez,
the station where Nelson camped and worked during his first visit
to the area (Goldman, 1951: 115). The holotype is more similar in
size and other features of the shell to specimens from 3.0 miles SE
of Tuxtla Gutierrez than to available specimens from other localities.
The specimens from 7.3 miles SE Tuxtla Gutierrez differ from
others in that they are smaller, more slender, and have more rugose
sculpture on the outer surface of the shell. Other features of the
shell are normal. Measurements of these specimens are: length, 40.0-
43.1 mm; width, 14.9-15.8 mm; aperture height, 9.6-10.5 mm; aperture
width, 8.7-9.6 mm; 7.7-8.9 whorls.

Coelocentrum tyla new species
SHELL.-(fig. 27.) Medium-large; light brown, dull; thin; cylindric-
conical in shape. Decollate, 13.3-15.3 whorls remaining; initial whorl


FIGURE 27. Coelocentrum tyla n. sp. A, B.-Holotype (UF 19044). C.-
Paratype (UF 19045).




THOMPSON: MEXICAN LAND SNAILS


0.48-0.55 times diameter of shell; whorls gradually increase in di-
ameter to about the ninth or tenth whorl, below which point the shell
becomes more nearly cylindrical; last 1-2 whorls decreasing slightly in
diameter. Aperture extending forward on a short neck that is about
1 as long as diameter of last whorl; inner base of neck strongly angu-
late. Aperture rhomboid, higher than wide. Peristome moderately
thickened, reflected completely around aperture. Interior of aper-
ture and peristome white. Umbilicus rimate or imperforate; axial
puncture open. Whorls weakly convex. Suture shallow, narrow.
Sculpture consisting of fine flattened, irregular, occasionally indis-
tinct, oblique, recurved axial threads; 114-178 threads on 4th from
last whorl. Many very minute, flattened granules superimposed on
and between threads. Spiral sculpture absent. Axial pillar hollow,
large; pillar with axial ribs slightly less than 1/2 diameter of shell.
Pillar bearing a strongly convex spiral crest that lies slightly below
the center of the pillar within each whorl and is continuous through-
out length of shell to penultimate whorl. A relatively narrow, deep
channel lies below the crest and occupies the lower 1/ of the pillar
within each whorl. The pillar bears about 20-30 thin, oblique axial
ribs that extend from the top of the whorl to the top of the crest,
where the ribs become much higher and are titled forward. Ribs
weakly serrate and thin throughout most of shell; within antepenulti-
mate and penultimate whorls ribs become thickened into elongate
rounded nodules on top of spiral crest.
Juvenile shell unknown.
Measurements of holotype: length, 44.1 mm; width, 12.1 mm; aper-
ture height, 6.9 mm; aperture width, 6.7 mm; 14.6 whorls remaining;
diameter of first whorl, 6.3 mm.
Measurements of paratypes: length, 39.2-45.0 mm; width, 11.5-
12.6 mm; aperture height, 6.2-7.3 mm; aperture width, 6.1-6.8 mm.
TYPE LOCALITY.-CHIAPAS: 8.6 mi. E by road from Chiapa de
Corzo; 3100' elevation. The type locality lies in a wooded, semimesic
ravine. Snails were found in mulch and talus at the base of a small
limestone ledge. HOLOTYPE: UF 19044, collected 11 July 1965 by
Fred G. Thompson. PARATYPES: UF 19045 (4); same data as the
holotype. Shell characters and measurements were taken from two
other specimens that were sacrificed for anatomical studies.
REMARKS.-C. tyla is distinguished from all other species of the
subgenus Coelocentrum by its high axial ribs on the internal pillar
and their modification into relatively large knobs within the penulti-




BULLETIN FLORIDA STATE MUSEUM


mate and antepenultimate whorls. It is most similar in size and gen-
eral appearance to C. tomacella (Morelet), which differs by being
slightly smaller in all dimensions and by having uniformly low and
weak ribs on the pillar (Pilsbry, 1903: 38-39).
ETYMOLOGY.-The name tyla is derived from the Greek tylos,
meaning knot or knob, and refers to the sculpture on the axis.

Coelocentrum cataclines new species
SHELL.-(fig. 28.) Large; light brown, dull; thin, fragile; cylindric-
terete; decollate, 10.3-12.5 whorls remaining. Width of initial whorl
about 0.44-0.49 times diameter of shell, whorls gradually increasing
in size, reaching maximum width at about 7th or 8th whorl; last 1 1/2-
2 whorls decreasing slightly in diameter. Aperture extending forward


FIGURE 28. Coelocentrum cataclines n. sp. A, B.-Holotype (UF 19031).
C.-Paratype (UF 19032).

on a short neck that is about 1/4-1/ as long as diameter of last whorl;
inner base of neck strongly cristate. Aperture subrhomboid, higher
than wide; basal and outer margins rounded, parietal and columellar
margins nearly straight. Peristome slightly thickened and strongly
reflected; interior of aperture and peristome white. Umbilicus im-
perforate; apical perforation open. Surface of shell sculptured with


Vol. 12




THOMPSON: MEXICAN LAND SNAILS


many weak, occasionally indistinct, low, recurved axial threads;
threads on early whorls of spire stronger than elsewhere; about 104-
130 threads on 4th from last whorl; threads more widely spaced on
early whorls and more closely spaced on penultimate and last whorls.
Threads and interspaces finely punctate with very minute granules.
Spiral sculpture absent. Axis hollow, highly modified into a broad
flaring hollow lamella that is about 2/% diameter of shell at its widest
point. Lamella begins as a spiral swelling just below middle of
whorls at top of spire and gradually increases in size to become a
wide, flattened, sloping spiral lamella. Axis in last 6-7 whorls with
rather regularly spaced, slightly oblique low axial ribs that extend
from top of pillar to crest of lamella where they become most pro-
nounced and onto underside of lamella to its base. Remaining portion
of axis within each whorl smooth. Ribs in last 2-2.5 whorls modified
into weak knobby crests on edge of lamella.
Juvenile shell unknown.
Measurements of holotype: length, 69.1 mm; width, 18.4 mm;
aperture height, 13.2 mm; aperture width, 11.6 mm; 12.2 whorls
remaining; diameter of first whorl, 8.2 mm.
Measurements of paratypes: length, 49.7-59.9 mm; width, 15.8-
17.8 mm; aperture height, 10.0-14.0 mm; apterture width, 9.7-11.8
mm.
TYPE LOCALITY.-CHTAPAS: limestone knoll 15.8 mi. NW by road
from Ocozocoautla, 2700' elevation. Snails were collected from mulch
and debris at the ~1adf low ledges on the side and at the bottom of
the knoll. The area was covered with tropical wet forest, but was
relatively open at the ground level. HOLOTYPE: UF 19031; collected
21 July 1965 by Mary Lynn Paulson. PARATYPES: UF 19032 (2); UF
19033 (5); same locality as the holotype.
REMARKs.-C. cataclines is distinguished from all other species of
Coelocentrum by its large size, sculpture and axial modifications. It
is most similar to C. tyla new species, but is much larger and is more
extreme in the projection of the axial swelling. C. cataclines bears
some resemblance to C. palmeri Dall and Bartsch because of its axial
development, but differs from that species by having thin oblique
ribs on the spiral swelling and by lacking spiral threads along the
sutures of the whorls (Dall, 1908: 177-178).
ETYMOLOGY.-The name cataclines is derived from the Greek
cata + clinein, meaning a spiral stairway, and refers to the nature
of the axis.




180 BULLETIN FLORIDA STATE MUSEUM Vol. 12

Eucolodium (Oligostylus) hegewischi (Bartsch)
Bulimus truncatus Pfeiffer, 1841; Symb. Hist. Helic.: 43-44. (Not Bulimus
truncatus Bruguiere, 1792; Encycl. Method.: 319).
Oligostylus hegewischi Bartsch, 1947; J. Washington Acad. Sci., 37:286, 1948;
J. Washington Acad. Sci., 38: 350-351.
MICHOACAN: 1.4 mi. W Angangueo, 9000' elevation (UF 19063
[25]).
The juvenile shell is illustrated in fig. 22D. Embryonic whorls 5;
first 2 embryonic whorls rapidly enlarging, 2nd whorl 2.1-2.2 mm
wide, following 3 whorls decreasing slightly in size. Neanic whorls
increasing in size to adult shell. Embryonic whorls separated from
neanic whorls by a slight crease. Outline of juvenile shell slightly
concave. First 2 embryonic whorls smooth, remaining embryonic
whorls with weak low threads that begin along the upper suture and
become increasingly long and distinct. Following neanic whorls with
low thread-riblets that continue into adult sculpture. Rate of growth
of juvenile shell indicates about 11-12 whorls are lost above point of
decollation in adult shell.

Eucolodium decollatum (Nyst)
Pupa decollata Nyst, 1841; Bull. de 1'Acad. Roy. de Sci. Belles-Lettres de Bruxel-
les, 8:344; upper fig. of pl.
Eucolodium decollatum (Nyst), Pilsbry, 1903; Man. Conch., Ser. 11, 15:3-4; pl.
1, fig. 1; pl. 4, fig. 9.
Cylindrella ghiesbreghti Pfeiffer, 1856; Proc. Zool. Soc. London :380; pl. 36, fig. 1.
Eucolodium decollatum var. ghiesbreghti (Pfeiffer), Pilsbry, 1903; Man. Conch;
Ser. 11, 15:4-5; pl. 5, figs. 18-21.
TABAsco: mogote 2.4-2.6 mi. E Teape; UF 19047-19049 (8).
Pilsbry (1903: 4-5) noted that the only distinction between
decollatum and ghiesbreghti was the lighter color of decollatum
which could have been due to weathering of the type specimen,
but he retained the name ghiesbreghti as a variety of decollatum
because of its long standing in the literature. Fresh specimens before
me vary from reddish-chocolate to very pale yellow, and allow no
distinction between the two named forms.

Eucolodium otoides new species
SHELL.-(fig. 29.) Moderately large, solid, light yellowish gray to
light reddish brown in color. Elongate conical, approaching conical-
terete; dull, periostracum generally worn away. Decollate, 7.6-7.9
whorls remaining; first whorl 0.48-0.50 times diameter of shell. Im-
perforate. Last whorl with a very vague circumbasal ridge. Aper-




1968 THOMPSON: MEXICAN LAND SNAILS 181


FIxcur 29. Eucolodium otoides n. sp. Holotype (UF 19050).


ture free from preceding whorl, projecting forward on a short neck.
Aperture elongate auriculate, 1.26-1.40 times as long as wide; 0.29-0.30
times length of shell; upper corner strongly angulate. Outer and
basal lip evenly rounded; columellar margin and basal margin form-
ing a .weak angle, both slightly concave into aperture; columellar
lamella extending conspicuously into aperture along columellar
margin. Peristome reflected, moderately thickened, particularly along
outer lip. Aperture arched and slightly oblique in lateral profile.
Sculpture on early whorls consisting of vague, irregular, frequently
incomplete riblets spaced about 3 mm. On later whorls these be-
come obsolete and are reduced to irregular coarse incremental stria-
tions that become even finer on the last whorl. Superimposed on
axial striations, particularly along sutures, are very fine, frequently
indistinct spiral striations and threads. Columella twisted, with a
wide, flat spiral lamella that is crenulate along outer margin.
Measurements of holotype and paratype (paratype in paren-
theses): length, 58.6 (57.5) mm; width, 17.9 (18.3) mm; aperture





182 BULLETIN FLORIDA STATE MUSEUM Vol. 12

length, 16.7 (17.5) mm; aperture width, 11.9 (13.9) mm; 7.9 (7.6)
whorls.
TYPE LOCALITY. CHIAPAS: forested ravine 3.5 mi. by road S
Rayon; 5500' elevation. HOLOTYPE: UF 19050; collected 10 July
1965 by Fred G. Thompson. PARATYPE: UF 19051; same locality as
holotype.
REMARKs.-Three other species are recognized in Eucolodium
(s.s.): E. decollatum (Nyst), E. compactum Pilsbry, and E. mexi-
canum (Pfeiffer). E. otoides is most similar in size, solidity, and
sculpture to E. compactum. It differs from all three species by the
shape of its aperture, by the extent to which the columellar lamella
projects into the aperture, and by the conical nature of the spire.
The other three species have a shorter, more nearly circular aperture,
the columellar lamella does not project into the aperture nearly as
conspicuously, and they are more nearly cylindrical in shape.
ETYMOLOGY.-The name otoides is derived from the Greek otos,
meaning ear, and refers to the ear-like shape of the aperture.





THOMPSON: MEXICAN LAND SNAILS


LITERATURE CITED

Bartsch, Paul. 1906. The Urocoptid mollusks from the mainland of America
in the collection of the United States National Museum. Proc. U. S. Natl.
Mus. 31: 109-160; pls. 3-5.
Dall, William H. 1896. Report on the mollusks collected by the International
Boundary Commission of the United States and Mexico, 1892-1894. Proc.
U. S. Natl. Mus. 19: 333-379; pls. 31-33.
1908. Descriptions and figures of some land and freshwater shells
from Mexico, believed to be new. Proc. U. S. Natl. Mus. 35: 177-182; pls.
29-30.
S1910. Two new Mexican landshells. Nautilus 24: 34-36.
Goldman, E. A. 1951. Biological investigations in Mexico. Smiths. Misc. Coll.
115: i-xiii, 1-476; pls. 1-70.
Martens, E. von. 1890-1900. Biologia Centrali-Amcricana. Mollusca: i-xxviii,
1-706; pls. 1-44. London, Taylor and Francis.
Pfeffer, G. 1887. XII. Anisospira Strebelii, nov. spec. aus Mexico. Verh. d.
Vereins Naturwiss. Unterhaltung zu Hamburg 3: 117-118.
Philippi, R. A. 1874. Abbildungen und Beschreibungen Neuer oder Wenig
Gekennten Conchylien 2: 1-120. Published by the author.
Pilsbry, Henry A. 1903. Manual of conchology, Series 11, 15: i-viii, 1-323;
pls. 1-65.
S1909. New mollusks collected by Mr. A. A. Hinkley in San Luis Potosi,
Mexico. Nautilus 22: 138-140.
--- 1939. A new mexican Coclocentrum. Nautilus 53: 27; pl. 7, fig. 5.
--- 1946. Land mollusca of North America. Monogr. Acad. Nat. Sci.
Philadelphia (3); vol. 2, pt. 1: i-vi, 1-520; figs. 1-281.
Solcm, A. 1957. Notes on some Mexican land snails. Notulae Naturae (298):
1-18; pl. 1.
Strebel, H. 1880. Beitrag zur Kenntniss der Fauna Mexikanischer Land und
Susswasser-Conchylien, pt. IV. Hamburg: 1-112; pls. 1-15. Published by
the author.
Thompson, F. C. 1963. New land snails from El Salvador. Proc. Biol. Soc.
Wash. 79: 19-32; figs. 1-2.




ERRATA

BULLETIN FLORIDA STATE MUSEUM, Volume 12, number 3

P. 137, line 3: change "(fig. 3)" read "(fig. 4)"
P. 139, bottom line: add "Scale = 1 mm."
P. 142, delete first line
P. 149, line 20: for "pillar of axis" read "si;ell"
P. 166, bottom line: add "Scale 1 mm."
P. 171, line 30: for "adolphos" read "adelphos"
P. 179, line 25: change "last" to "base"







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