A Review of the North American Freshwater Snail Genus Pyrgulopsis

ABSTRACT
Hershler, Robert. A Review of the North American Freshwater Snail Genus Pyrgulopsis
(Hydrobiidae). Smithsonian Contributions to Zoology, 554, 115 pages, 53 figures, 2 tables,
1994.—The Recent nominal species belonging to the hydrobiid snail genus Pyrgulopsis Call and
Pilsbry, 1886, are reviewed. Pyrgulopsis is a large group of 65 Recent species inhabiting diverse
inland waters of North America. This genus is distinguished from other members of the
subfamily Nymphophilinae by the combination of small size; generally simple, ovate-conic
shell; and penis ornamented with relatively few glands.
Members of this genus have a globose to elongate-conic shell with near smooth to strongly
punctate protoconch, smooth or rarely carinate teleoconch, and simple apertural lip often
loosened from the body whorl. The taenioglossate radula features a central radular tooth with
well-developed lateral angles, narrow basal process, and, usually, a single pair of basal cusps.
The operculum generally is paucispiral with eccentric nucleus. The ventral operculum is notable
for its variably thickened attachment scar margin and central callus. The caecal chamber of the
stomach is variably developed. Animal pigmentation is variable, sometimes including dark
stripes along the mantle. Cephalic tentacle ciliation generally is weak. The gonads usually are of
simple lobes, and sometimes overlap the stomach. The prostate gland usually has a small pallial
section and the vas deferens usually exits from the gland sub-terminally. The penis is generally
large and distally bifid; with a terminal filament bearing the vas deferens, and accessory lobe
(sometimes absent). The penis surface is very weakly ciliated and is variably ornamented with
dorsal and ventral glands. The albumen gland usually has a small pallial section. The capsule
gland is almost always bipartite, and contains a well-developed ventral channel. The genital
aperture is either simple or opens to an anterior vestibule. The coiled oviduct usually is simple,
and joins the bursal duct just behind, to well anterior to, the pallial wall. Both bursa copulatrix
and seminal receptacle usually are present, the former being larger and often at least partly
posterior to the albumen gland. The bursal duct is of variable size and shape, and often
embedded, sometimes deeply so, within the albumen gland. The seminal receptacle is usually
just behind the coiled oviduct and typically has a short duct. Females are oviparous, and lay
single, hemispherical egg capsules.
A cladistic analysis of relationships among 60 species was conducted using Nymphophilus
Taylor as single outgroup. Monophyly of Pyrgulopsis was supported by 15 character-state
transformations, including six non-homoplasious synapomorphies. Four large clades were
recognized: a group of nine species distributed in Mississippi River drainage and other waters
to the east, a group of six species from southern Nevada and southeastern Arizona; a group of
10 species from eastern California, northern Arizona, and Snake River drainage; and a group of
18 species scattered throughout the West. The remaining 17 western taxa included four species
occupying basal positions on the cladogram, a poorly resolved group of eight species, and two
small clades consisting of two species from northern Arizona; and three widely disjunct species
from northern Mexico, Snake River drainage, and southeastern California.
The following genera herein are added to the list of junior subjective synonyms of
Pyrgulopsis: Savaginius Taylor, 1966a, Apachecoccus Taylor, 1987, and Yaquicoccus Taylor,
1987. Fluminicola avernalis carinifera Pilsbry, 1935, is elevated to full species status herein
—this and fifteen other species are newly allocated to Pyrgulopsis. Fontelicella pinetorum
Taylor, 1987, is a junior subjective synonym of Pyrgulopsis kolobensis (Taylor, 1987); and
Pyrgulopsis wabashensis Hinkley, 1908a, is a junior subjective synonym of Pyrgulopsis
scalariformis (Wolf, 1869). A new name, Pyrgulopsis bryantwalkeri, is proposed for
Fluminicola nevadensis Walker, 1916 (not Pyrgula nevadensis Stearns, 1883).
OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is
recorded in the Institution's annual report, Smithsonian Yera. SERIES COVER DESIGN: The coral
Montastrea cavernosa (Linneaus).
Library of Congress Cataloging-in-Publication Data
Hershler, Robert
A review of the North American freshwater snail genus Pyrgulopsis (Hydrobiidae) / Robert Hershler.
p. cm.—(Smithsonian contributions to zoology ; no. 554)
Includes bibliographical references.
1. Pyrgulopsis—North America—Classification. I. Title. II. Series.
QL1.S54 no. 554 [QL430.5.H9] 591 s-dc20 [594'.3] 93-47246
® The paper used in this publication meets the minimum requirements of the American
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