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SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 612

Systematics of the North and Central American Aquatic Snail Genus Tryonia (Rissooidea: Hydrobiidae)

Robert Hershler

Smithsonian Institution Press

Washington, D.C.

2001

ABSTRACT

Hershler, Robert. Systematics of the North and Central American Aquatic Snail Genus Tryonia (Rissooidea: Hydrobiidae). Smithsonian Contributions to Zoology, number 612, 53 pages, 29 figures, 2 maps, 2001.—Morphological variation among members of the genus Tryonia (and its subgenus Paupertryonia) is congruent with a recently published phylogenetic analysis based on mtDNA sequences that showed that these taxa are polyphyletic assemblages of ecologically similar snails. Tryonia is reconstituted as a North and Central American monophyletic subunit of the subfamily Cochliopinae based on a synapomorphy of posterodorsal insertion of the vas deferens into the prostate gland. Presumably derived modifications of the shell, radular teeth, and genitalia unite groups of species within this genus.

Tryonia is redefined and 18 species are recognized in the genus. Congeners are T. aequicostata (Pilsbry, 1890a), distributed in the Florida peninsula; T. cheatumi (Pilsbry, 1935) and T. circumstriata (Leonard and Ho, 1960), Rio Grande basin; T. hertleini (Drake, 1956), interior drainage of northeast Mexico; T. clathrata Stimpson, 1865, and T. gilae Taylor, 1987, lower Colorado River basin; T. angulata Hershler and Sada, 1987, T. elata Hershler and Sada, 1987, T. ericae Hershler and Sada, 1987, T. margae Hershler, 1989, T. monitorae Hershler, 1999, T. rowlandsi Hershler, 1989, T. salina Hershler, 1989, and T. variegata Hershler and Sada, 1987, southern Great Basin; T. porrecta (Mighels, 1845), lower Colorado River basin, Great Basin, Hawaii; T. quitobaquitae Hershler in Hershler and Landye, 1988, Rio Sonoyta basin; T. imitator (Pilsbry, 1899), southern California coast; and T, exigua (Morelet, 1851), Lake Petén Itza, Guatemala. Tryonia protea (Gould, 1855) is found to be a junior synonym of Paludina porrecta Mighels, 1845.

Tryonia kosteri Taylor, 1987, from the Pecos River basin, is found to be a member of the genus Durangonella Morrison, 1945, which was previously known only from the Mexican Plateau. A new North American genus, Pseudotryonia Hershler, is erected for three species previously placed in Tryonia. Pseudotryonia is diagnosed by a combination of genitalic characters. Its congeners are P. brevissima (Pilsbry, 1890b), Florida panhandle; P. adamantina Taylor, 1987, and P. alamosae Taylor, 1987, Rio Grande basin; and an undescribed species from the Tombigbee River basin. A new monotypic genus, Ipnobius Hershler, is erected for Tryonia robusta Hershler, 1989, from Death Valley, California. Ipnobius is diagnosed by genitalic autapomorphies. Lectotypes are designated for Melania exigua Morelet, and Amnicola protea Gould.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded in the Institution's annual report, Annals of the Smithsonian Institution. SERIES COVER DESIGN: The coral Montastrea cavernosa (Linnaeus).

Library of Congress Cataloging-in-Publication Data

Hershler, Robert

Systematics of the North and Central American aquatic snail genus Tryonia

(Rissooidea: Hydrobiidae)/ Robert Hershler.

p. cm. — (Smithsonian contributions to zoology ; no. 612)

Includes bibliographical references (p. )

1. Tryonia-Classification. I. Title. II. Series.

QL1.S54 no. 612 [QL430.5.H9] 590 s-dc2l [594′.32]

2001020792

The paper used in this publication meets the minimum requirements of the American National Standard for Permanence of Paper for Printed Library Materials Z39.48—1984.

Contents

Introduction

Material and Methods

Acknowledgments

Family HYDROBIIDAE Troschel, 1857

Subfamily COCHLIOPINAE Tryon, 1866

Genus Tryonia Stimpson, 1865

Tryonia aequicostata (Pilsbry, 1890)

Tryonia angulata Hershler and Sada, 1987

Tryonia cheatumi (Pilsbry, 1935)

Tryonia circumstriata (Leonard and Ho, 1960)

Tryonia clathrata Stimpson, 1865

Tryonia elata Hershler and Sada, 1987

Tryonia ericae Hershler and Sada, 1987

Tryonia exigua (Morelet, 1851)

Tryonia gilae Taylor, 1987

Tryonia hertleini (Drake, 1956)

Tryonia imitator (Pilsbry, 1899)

Tryonia margae Hershler, 1989

Tryonia monitorae Hershler, 1999

Tryonia porrecta (Mighels, 1845), new combination

Tryonia quitobaquitae Hershler in Hershler and Landye, 1988

Tryonia rowlandsi Hershler, 1989

Tryonia salina Hershler, 1989

Tryonia variegata Hershler and Sada, 1987

Genus Durangonella Morrison, 1945

Durangonella kosteri (Taylor, 1987), new combination

Pseudotryonia Hershler, new genus

Pseudotryonia adamantina (Taylor, 1987), new combination

Pseudotryonia alamosae (Taylor, 1987), new combination

Pseudotryonia brevissima (Pilsbry, 1890), new combination

Pseudotryonia sp

Ipnobius Hershler, new genus

Ipnobius robustus (Hershler, 1989), new combination

Figures

Literature Cited

Requirements for Smithsonian Series Publication

Systematics of the North and Central American Aquatic Snail Genus Tryonia (Rissooidea: Hydrobiidae)

Robert Hershler

____________

Robert Hershler, Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C., 20560.

Review Chairman: Kristian Fauchald, Department of Invertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, D.C., 20560.

Reviewers: Terrence J. Frest, Deixis Consultants, 2517 NE 65th Street, Seattle, Washington, 98115; and one anonymous reviewer.

Introduction

The gastropod subfamily Cochliopinae (family Hydrobiidae), composed of 31 genera and more than 260 Recent species, is one of the largest groups of aquatic mollusks in the New World (Hershler and Thompson, 1992). As is the case for hydrobiids generally, the systematics of cochliopine snails is in an early stage of refinement. Monophyly of the Cochliopinae has not been rigorously established, although diagnostic features include several possible synapomorphies within the context of the Hydrobiidae, notably the posterior folding of the female glandular oviduct (Hershler and Thompson, 1992). Phylogenetic structure of the Cochliopinae has not been evaluated, and most of its species are still known only by their shells. In what was intended as a first step toward revising the Cochliopinae, Hershler and Thompson (1992) redefined its genera based on shell and anatomical characters, but this study focused largely on type species only.

Tryonia Stimpson, 1865, is the fourth largest cochliopine genus, with 23 Recent species currently placed in the group (Hershler and Thompson, 1992; Hershler, 1999). Tryonia ranges across southern North America, with most congeners concentrated in the major drainages of the American Southwest. Although present in the Rio Grande basin and Gulf Coastal and Atlantic drainages in Florida, Tryonia is absent from the intervening southern Great Plains and Mississippi River basin. Although most Tryonia species are restricted to springs, which often are thermal and highly mineralized, some congeners also live in lakes (Thompson, 1968, as Hyalopyrgus), and one species is restricted to brackish, coastal waters (Kellogg, 1985). When present, these tiny snails are typically among the more abundant members of the invertebrate benthos (e.g., Meffe and Marsh, 1983). The genus also is of interest in terms of reproductive biology because one species is parthenogenetic (Mulvey and Hershler, ms), and many congeners have skewed sex ratios and marked sexual dimorphism in body size (Thompson, 1968 (as Hyalopyrgus); Taylor, 1987). Owing to their typical narrow distributions and small habitats, western congeners are especially vulnerable to perturbations relating to water development: one species (T. alamosae) is currently listed as endangered by the United States Fish and Wildlife Service (USDI, 1991), and three others (T. adamantina, T. kosteri, T. stocktonensis (= T. circumstriata)) are candidates for addition to this list (USDI, 1997).

Most species of Tryonia are readily distinguished by shell and penial characters, and their taxonomy has been little confused at the specific level; however, the scope and content of the genus has been unstable and continues to rest on a shaky foundation. Tryonia was established as a monotypic genus by Stimpson (1865) for his new species, T. clathrata, which was described from material that probably originated from the White River trough in southeast Nevada (Stearns, 1893, 1901; Morrison, 1940; Taylor, 1966b). Although Tryonia is considered exclusively North American in the most recent literature (Taylor, 1987; Hershler and Thompson, 1992), Central and South American taxa previously have been placed in the genus, beginning with Tate (1870) and especially by Taylor (1966b). Allocations of Neogene fossils from tropical America to Tryonia remain controversial (Nuttall, 1990; Wesselingh, 1996). Whereas Hershler and Thompson (1987) and Thompson (1999) allocated snails from the southeast United States to Tryonia, Taylor (1987) treated the genus as exclusively western.

Stimpson (1865) originally diagnosed Tryonia by the narrow, ribbed shell of its type species. A simple conchological definition of Tryonia remained in place for more than 100 years until a limited anatomical context was provided by Taylor (1966b), who placed the genus in the subfamily Littoridininae (= Cochliopinae), which he characterized in part by penial ornament of bulbous or elongate lateral lobes. In a subsequent publication, Taylor (1987) diagnosed Tryonia by features that included a penis ornamented with a small number of glandular papillae and having a bulbous, pigmented distal portion, with a terminal stylet (Figure 1); however, neither these nor the additional female genitalic features used by Hershler and Thompson (1992) to diagnose Tryonia are unique to the group. The concept of Tryonia also is vague because the anatomy of only five congeners has been described in detail (T. angulata, Hershler and Sada, 1987; T. clathrata, Hershler and Thompson, 1987, 1992; T. gilae, T. quitobaquitae, Hershler and Landye, 1988; T. monitorae, Hershler, 1999). Most other congeners are known only in terms of shell and external morphology (e.g., species described by Taylor, 1987) or only by their shells (e.g., T. hertleini, T. imitator).

During the past decade alcohol-preserved material was acquired for 22 of the 23 extant species assigned to Tryonia in recent treatments. A survey of morphological variation has revealed that only 17 of these congeners conform to the anatomical groundplan of the type species, and it suggested a basis for recognizing this subset of taxa as a monophyletic unit. The purposes of the present study are to (1) redefine and revise the content of Tryonia, (2) briefly describe the Recent species of Tryonia s.s., and (3) transfer five species incorrectly identified as Tryonia in the recent literature to three other genera, two of which are newly described herein. This revision of Tryonia-like snails is completely congruent with a phylogenetic analysis based on mtDNA sequences, which revealed this genus as composed of four distinct lineages that together do not form a monophyletic group (Hershler, Liu, and Mulvey, 1999, fig. 3). This paper is the third and final part of a series reviewing the larger genera of western North American hydrobiid snails (Hershler, 1994; Hershler and Frest, 1996).

MATERIAL AND METHODS

Tryonia brunei Taylor, 1987, was the only extant species of Tryonia s.l. for which anatomical material could not be obtained, because this snail could not be found at its only known locality in west Texas. In the wake of the present study, available data (Taylor, 1987) are not sufficient to confidently assign this species to a genus. For the same reason, the various fossil and subfossil species that have been assigned to Tryonia are not treated in this study.

Snails used for anatomical study were fixed in dilute formalin (10% of stock solution) and were preserved in 70% ethanol. Unless otherwise specified, dissected specimens were relaxed with menthol crystals (prior to fixation) so that the head-foot and penis were extended. Prior to dissection of snails, shells were removed by immersion in dilute hydrochloric acid. Sections were cut at 4 μm and stained with hematoxylin and eosin. Methods of preparation of material for scanning electron microscopy follow Hershler (1998). All drawings were made with a camera lucida. Penial drawings were of whole-mounted preparations that were stained in hematoxylin and then cleared.

In referring to size of shells, the following states were recognized: small (shell height<2.0 mm), medium (2.0–5.0 mm), and large (>5.0 mm). Other character states are either keyed to an illustration or follow those described and illustrated by Hershler and Ponder (1998). Length of the outer wing of the lateral radular tooth was measured along its long axis, rather than parallel to the dorsal edge of the tooth face (fide Hershler and Ponder, 1998, fig. 9a), so that this feature could be described independently of wing flexure (e.g., angling of the wing relative to the tooth face).

Inasmuch as most congeners have been well described in terms of traditional characters (Thompson, 1968; Hershler and Sada, 1987; Taylor, 1987; Hershler, 1989, 1999), all of this information is not reiterated herein, but instead capsule summaries are provided that focus on diagnostic and newly acquired data. Owing to the limited alcohol-preserved material available for most species, sexual dimorphism in body size was not analyzed within the context of this study. Note that shape of the wings on the marginal radular teeth may provide useful information for discriminating among species of Tryonia-like taxa, but it was not studied in sufficient detail for utilization herein.

All type specimens cited have been examined. Holotypes for species described by Taylor (1987) are alcohol-preserved specimens whose shells are now softened. Paratype shells are instead figured for these taxa. This study is largely based on material reposited at the National Museum of Natural History (NMNH) (which houses the collections of the former United States National Museum (USNM), Smithsonian Institution), although type specimens and additional material from the Academy of Natural Sciences of Philadelphia (ANSP), Bernice P. Bishop Museum (BPBM), California Academy of Sciences (CAS), Florida Museum of Natural History (UF), Los Angeles County Museum of Natural History (LACM), The [British] Natural History Museum (BMNH), Santa Barbara Museum of Natural History (SBMNH), and University of Michigan Museum of Zoology (UMMZ) also were examined. In the “Material Examined” section of each species account, reference is only made to material figured in this paper and to alcohol-preserved material used for dissection.

ACKNOWLEDGMENTS

The following individuals and institutions loaned specimens: G. Rosenberg (ANSP), R. Cowie (BPBM), T. Gosliner and E. Kools (CAS), F.G. Thompson (UF), L. Groves and J.H. McLean (LACM), P. Mordan (BMNH), P.V. Scott (SBMNH), and J.B. Burch (UMMZ). Art Metcalf (University of Texas, El Paso) greatly facilitated the study of species described by Taylor (1987) by distributing paratypes of these taxa to the NMNH. Fred G. Thompson and J.J. Landye generously provided live or freshly preserved material for various species. Yolanda Villacampa (NMNH) gathered radular data, prepared scanning electron micrographs, and prepared photographic prints. Kary Darrow (NMNH) inked anatomical drawings and Molly Ryan (NMNH) prepared shell drawings and assisted with the preparation of plates. Dan Cole (NMNH) generated the base map of North and Central America. This study was partly supported by awards from the Bureau of Land Management (United States Department of the Interior), Biological Resources Division of the United States Geological Survey, and the Smithsonian Institution's Scholarly Studies Program. Terrence J. Frest and an anonymous reviewer are thanked for their constructive comments on a draft version of this paper.

Family HYDROBIIDAE Troschel, 1857

The name is preoccupied in Coleoptera (Newton and Thayer, 1990); see Giusti et al. (1998) for a proposal to remove the homonymy.

Subfamily COCHLIOPINAE Tryon, 1866

Genus Tryonia Stimpson, 1865

Tryonia Stimpson, 1865:54 [type species: Tryonia clathrata Stimpson, 1865, by original designation].—[Not Tryonia Stephenson, 1941:331; Mollusca: Buccinidae?]

Calipyrgula Pilsbry, 1934:15 [type species: Calipyrgula carinifer Pilsbry, 1934, by original designation].—Hershler and Thompson, 1992:107 [synonymized with Tryonia.]

Hyalopyrgus Thompson, 1968:43 [type species: Bythinella aequicostata Pilsbry, 1890a; by original designation].—Hershler and Thompson, 1987:26 [synonymized with Tryonia].

Paupertryonia Taylor, 1987:38 [type species: Potamopyrgus cheatumi Pilsbry, 1935, by original designation; proposed as subgenus of Tryonia].—Hershler and Thompson, 1992:107 [synonymized with Tryonia.]

DIAGNOSIS.—Shell ovate-conic to turriform, smooth or variously sculptured. Penis ornamented with 2–6 glandular papillae borne singly along edges; distal penis often swollen along inner edge. Females ovoviviparous. Bursa copulatrix and seminal receptacle present; renal oviduct a large coil, usually pigmented; sperm duct coiled, opening to bursal duct behind pallial wall; sperm tube variable in length.

DESCRIPTION.—Shell (Figure 4) gray or clear, 1.2–7.5 mm tall, ovate-conic to turriform, whorls 3.75–9.75. Periostracum thin. Protoconch (Figure 5) small (<1.0 whorl), blunt, typically smooth; teleoconch smooth or variably sculptured. Aperture usually small, inner lip usually complete across parietal wall, umbilicus variable. Operculum (Figure 6) thin, ovate or ellipsoidal, multispiral, nucleus eccentric, inner side usually without pronounced muscle scar. Ctenidium well developed, connected to pericardium by short efferent vein (Figure 2B); lateral surfaces of ctenidial filaments often bearing low ridges (pleats). Osphradium small (Hershler and Landye, 1988, fig. 42), narrow, usually centrally positioned along ctenidial axis. Kidney having small pallial portion (Hershler and Landye, 1988, fig. 44a), opening slightly muscularized. Pericardium bulging slightly into pallial cavity (Hershler and Landye, 1988, fig. 44a). Style sac about as long as remainder of stomach, posterior caecum of stomach absent or small (Figure 2C). Rectum straight, anus near mantle edge. Radula with 35–55 tooth rows, cusps generally narrowly pointed. Central teeth trapezoidal, with 1–3 pairs of basal cusps (Figure 7). Lateral teeth with enlarged central cusp; basal tongue usually well developed; outer wing longer than width of tooth face (Figure 8). Inner (Figure 9) and outer (Figure 10) marginal teeth with numerous (15 to 37) cusps borne largely or entirely on outer side; teeth with well-developed wings on outer edge and narrow, raised area extending from face to base. Large testis of numerous (>10) stalked lobes; seminal vesicle exiting from and tightly coiled against left side of anterior portion of testis (Figure 2D). Prostate gland usually small, largely or entirely visceral (Hershler and Landye, 1988, fig. 44a). Visceral vas deferens opening to posterodorsal edge of prostate gland, pallial vas deferens exiting from anterior edge of prostate gland. Penis medium to large (Taylor, 1987, fig. 17d), narrow, base slightly expanded; terminal portion densely ciliated (Hershler and Landye, 1988, fig. 45), usually bulbous, often with swelling along inner edge (Figure 1). Penial-duct opening through well-developed stylet. Edges of penis ornamented with 2–6 glandular papillae borne singly. Penis usually darkly pigmented with melanin distally, variably pigmented elsewhere. Females ovoviviparous, brooded young few to many (2–30), of different sizes (having up to 2.5 shell whorls). Ovary a small, simple sac. Glandular oviduct large, mostly consisting of thin-walled brood pouch, usually with a single posterior fold, anterior opening muscular (Figure 3). Albumen gland very small relative to brood pouch (Figure 3C), positioned partly or entirely on right side of bursa copulatrix. Bursa copulatrix small relative to brood pouch (Figure 3A–C), duct exiting anterior edge. Seminal receptacle usually smaller than bursa copulatrix, positioned along anteroventral portion of bursa copulatrix, duct usually short (Figure 3D). Sperm duct entirely visceral, of two overlapping loops, opening to bursal duct. Oviduct issuing small gonopericardial duct proximal to coiled section. Renal oviduct a single, large, almost vertical loop; epithelium of loop usually invested with pigment. Distal to loop, oviduct connecting to seminal receptacle duct by a very short duct and opening to posterior edge of albumen gland. Sperm tube narrow, opening either in posterior or anterior portion of pallial cavity (opening fused with that of brood pouch in one species).

DISTRIBUTION.—Tryonia is disjunctly distributed in southern North America, with congeners living in the Florida Panhandle and in a western region extending from the Rio Grande basin to the Pacific Coast (Map 1). With the reallocation of Melania extended into northern Central America. This Guatemalan species is broadly disjunct from northern congeners, although this gap may be narrowed upon completion of ongoing taxonomic study of undescribed Tryonia-like snails (e.g., Williams et al., 1985; Minckley and Minckley, 1986) of northern Mexico. A clearer indication of the southern extent of the range of Tryonia must await further study of the poorly known hydrobiid fauna of Tropical America, which includes two Recent Brazilian species (described by Haas, 1938, 1949) that were allocated to the genus by Taylor (1966b). The allocation of a European fossil to Tryonia by Sandberger (1875:672) is disregarded herein following Fischer and Crosse (1891:256).

MAP 1.—Type locality areas of Tryonia species and junior synonyms thereof: 1, Lake Panasoffkee, Florida (T. aequicostata); 2, Oklawaha River drainage, Florida (Fontigens oxybeles=T. aequicostata); 3, upper Amargosa River drainage, Nevada (T. angulata, T. elata, T. ericae, T. variegata); 4, Phantom Lake, Texas (T. cheatumi); 5, late Pleistocene deposits, Pecos River drainage, Texas (T. circumstriata); 6, Pecos River drainage, Texas (T. stocktonensis=T. circumstriata); 7, White River drainage, Nevada (T. clathrata); 8, Lake Petén Itza, Péten, Guatemala (T. exigua); 9, Gila River drainage, Arizona (T. gilae); 10, interior drainage, Chihuahua, Mexico (T. hertleini); 11, coastal drainage, Santa Cruz, California (T. imitator); 12, Pleistocene deposits, San Pedro, California (Paludestrina curta=T. imitator); 13, lower Amargosa River drainage, California (T. margae, T. rowlandsi); 14, Monitor Valley, Nevada (T. monitorae); 15, Salton Sea basin (Amnicola protea, Pyrgulopsis imminens, Pyrgulopsis blakeana, Pyrgulopsis cahuillarum, all synonyms of T. porrecta); Rio Sonoyta drainage, Arizona (T. quitobaquitae); 17, lower Amargosa River drainage, California (T. salina). The Hawaiian type locality for T. porrecta is not shown.

REMARKS.—Live animals of three species (T. aequicostata, T. clathrata, T. gilae) were examined for details of head-foot morphology, which are as follows: snout rectangular, slightly expanded distally; cephalic tentacles slightly longer to about 150% length of snout, slender, tapering but little distally; snout and tentacles variably pigmented with melanin and scattered white or yellow granules, granules concentrated around eye-spot and along edges of “neck.” Ciliation of penis, head, and floor of pallial cavity was not studied in detail, but it is a possible source of additional characters. Previous work on four species has shown that the cephalic tentacles bear several longitudinal ciliary tracts, and the left tentacle has a few transverse bands of cilia along the outer edge basally (Hershler and Thompson, 1987, figs. 13–17; Hershler and Landye, 1988, fig. 41a–e). Note that in Tryonia (and the other genera reviewed below) the small protoconch is well demarcated only in uneroded embryonic shells (Figure 5E), and the transition between the end of growth in the brood pouch and the remainder of the teleoconch is usually indistinct.

In all members of Tryonia s.s. (except parthenogenetic T. porrecta), the visceral portion of the vas deferens inserts into the posterodorsal edge of the prostate gland (Figure 2A). The generalized condition in hydrobiid snails is for the visceral vas deferens to instead open to the ventral edge of the prostate gland. This condition apparently is unique to Tryonia within the Cochliopinae (and perhaps the Hydrobiidae generally) and therefore is hypothesized to be synapomorphic for the genus. A phylogenetic analysis of mtDNA sequences (Hershler, Liu, and Mulvey, 1999) also indicated monophyly (with high bootstrap support) of this group (minus T. exigua and T. hertleini, which were not included in the study). Tryonia is further distinguished from Mexipyrgus, which is closely similar morphologically (Hershler and Thompson, 1992) and has been identifed as the sister taxon to this genus based on mtDNA sequences (Hershler, Liu, and Mulvey, 1999), by the combination of a simple pattern of posterior looping of the glandular oviduct, and the small size of the bursa copulatrix relative to the brood pouch (compare Figure 3 with Hershler, 1985, figs. 41–43).

Although variation within Tryonia is not marked, several subunits of the genus are recognizable on the basis of morphology (and variously supported by mtDNA sequences; Hershler, Liu, and Mulvey, 1999). In two California congeners (T. imitator, T. salina), the basal tongue of the central radular teeth is weakly convex (Figure 7B), whereas in all other congeners, and in cochliopines generally, the basal tongue is V- or U-shaped (Figure 7A,D–F). These two species are further united by their relatively squat shells and broad central cusps of the central radular teeth. In 12 Tryonia species the terminal, bulbous portion of the penis has a pronounced swelling along the inner edge (e.g., Figure 1), whereas in the remaining six congeners, all from the Amargosa River and Gila River drainages (T.angulata, T. elata, T. ericae, T. gilae, T. rowlandsi, T. variegata), the bulb is evenly rounded (e.g., Figure 25F) as in other cochliopines. Therefore the distal swelling of the terminal bulb is hypothesized as a synapomorphy for this large group of congeners. In two congeners from the Amargosa River basin (T. elata, T. ericae), the long sperm tube abuts or is fused with (e.g., Figure 3A) the opening of the brood pouch. In all other congeners, the sperm tube opens in the posterior half of the pallial cavity (Figure 3B,C). Although both conditions occur among other cochliopines (Hershler and Thompson, 1992), Mexipyrgus, the presumed sister taxon to Tryonia (fide Hershler, Liu, and Mulvey, 1999) has a short tube; thus, the elongate condition is interpreted as a derived feature uniting these two congeners. Two congeners from the Great Basin (T. margae, T. monitorae) share a narrow, generally turriform shell (Figure 23G, H), whereas other congeners, Mexipyrgus, and cochliopine snails generally have a broader shell.

As pointed out by Kabat and Hershler (1993), early treatments of Tryonia as synonymous with one or more genera of Lake Baikal (Asia) hydrobioids (Dall, 1877; Tryon, 1883) were erroneous, as there are no anatomical features suggesting a close phylogenetic relationship between these broadly disjunct groups. Instead, Tryonia is related most closely to North American snails (Hershler, Liu, and Mulvey, 1999). Taylor (1966b) placed three genera of Neogene fossils from the Amazon basin of South America (Liris Conrad, 1871; Dyris Conrad, 1871; Conradia Wenz, 1925) in synonymy with Tryonia. These synonomies were rejected by Parodiz (1969), who instead compared the South American fossil taxa to Calipyrgula (which is now considered a synonym of Tryonia). Nuttall (1990) also maintained that Tryonia is distinct from these Neogene taxa, given the differences in their shells and their broadly disjunct temporal and geographic distributions. Wesselingh (1996), however, identified putative fossil Tryonia in intervening portions of central and northernmost South America. Given that Tryonia is diagnosed by an anatomical character and Recent Tryonia- like snails represent a phylogenetic mosaic (Hershler, Liu, and Mulvey, 1999), generic placement of these fossils probably will remain controversial until a stronger phylogenetic signal can be extracted from the shells of hydrobioid snails.

Taylor (1987) erected the subgenus Paupertryonia for five species from the Rio Grande basin, which he diagnosed by the absence of basal papillae on the penis. Based on the results of the current study, only the type species of this subgenus (T. cheatumi) is retained in Tryonia, whereas other members are allocated to Durangonella and a new genus described below. MtDNA sequences (Hershler, Liu, and Mulvey, 1999) congruently indicated that Paupertryonia consists of three distinct lineages (which together do not form a monophyletic group).

Tryonia aequicostata (Pilsbry, 1890)

Bythinella aequicostata Pilsbry, 1890a:86, pl. III: fig. 16 [type locality, Sumter County, Florida].—Baker, 1964:171 [lectotype selection].

Fontigens oxybeles Pilsbry, 1950:37–38, pl. 3: figs. 1, 1a. 1b [type locality, Silver Spring Run, Lake George, Marion County, Florida].—Thompson, 1968:46 [synonymized with Hyalopyrgus aequicostatus].

Hyalopyrgus aequicostatus.—Thompson, 1968:46–52, figs. 5, 25C, D, 29F, 32B, 39A–F, 49A–E, 59D–F, tables 2, 3 [reassignment; suggested type lot probably from Lake Panasoffkee, Florida].

Tryonia aequicostata.—Hershler and Thompson, 1987:26, figs. 3, 9, 10, 16, 17, 20, 24 [reassignment].

DIAGNOSIS.—Shell medium- to large-sized, conical. Penial ornament of 2 distal papillae along inner edge and an enlarged basal papilla on outer edge.

DESCRIPTION.—Shell (Figures 4G, 22A,B) 3.8–6.0 mm tall. Males much smaller than females (Thompson, 1968, tables 2, 3). Whorls, 4.5–7.5, medium convexity; teleoconch often sculptured with numerous low, collabral varices (up to 20 on body whorl); early portion also often lined with few, regularly spaced spiral lirae. Aperture ovate, lip very thin, incomplete across parietal wall except in largest specimens; shell imperforate or narrowly umbilicate. Operculum ovate, inner side with weak rim along outer edge. Ctendial filaments about 35, pleated. Stomach without posterior caecum. Radula with about 55 rows of teeth, length/width of ribbon 500%. Dorsal edge of central radular teeth well indented, basal tongue broadly V- shaped, central cusps narrowly pointed, lateral cusps 3–6; basal cusps 1 or 2, outer cusps often weakly developed. Lateral teeth having 2–4 cusps on inner side and 4–6 cusps on outer side; outer wing strongly flexed, length 200% width of tooth face; basal tongue weakly developed. Inner marginal teeth with 20–25 cusps, outer marginal teeth with 21–30 cusps.

Prostate gland very small, globular, pallial section 33% of total length. Distal penis pigmented, with pronounced swelling on inner edge, penial duct undulating (Figure 25A). Oviduct loop anterior-oblique, pigmented. Brood-pouch opening terminal, slightly muscularized; posterior portion with additional loop on left side of bursa copulatrix (Figure 3B); brooded embryos about 30, often forming 2 rows in posteriorly folded section. Albumen gland largely dorsal to bursa copulatrix. Bursa copulatrix small, narrowly ovate; seminal receptacle slightly smaller than bursa copulatrix, ovate. Sperm-duct opening to base of bursal duct. Sperm-tube opening in posterior 33% of pallial cavity.

DISTRIBUTION.—Upper Florida peninsula (Atlantic Ocean and Gulf of Mexico coastal drainages).

REMARKS.—Tryonia aequicostata is distinguished from other congeners by the typically incomplete parietal lip of the shell (Figure 4G) and by the massive basal papilla on the outer edge of the penis (Figure 25A). The looping of the brood pouch onto the left side of the bursa copulatrix (Figure 3B) also is unique in the genus.

MATERIAL EXAMINED.—UNITED STATES. Florida: Lake Eustis, Lake County, USNM 892070; Silver Spring Run, Lake George, Marion County, ANSP 186751 (holotype of Fontigens oxybeles); Wekiwa Springs, Seminole County, USNM 874831; Sumter County, ANSP 27985 (lectotype of Bythinella aequicostata).

Tryonia angulata Hershler and Sada, 1987

Tryonia angulata Hershler and Sada, 1987:810, 814–817, figs. 39a, 40, 41, 42a,d, 43, 44, table 2 [type locality, Fairbanks Spring, Ash Meadows, Nye County, Nevada].—Hershler, 1989, table 2.

DIAGNOSIS.—Shell medium-sized, ovate-conic to conic. Penial ornament of 2 distal and 1 basal papillae along inner edge and an occasional basal papilla on outer edge.

DESCRIPTION.—Shell (Figures 4F, 22C) 2.7–4.0 mm tall. Whorls, 5.0–7.0, weakly convex, with flattened, subsutural zone; early teleoconch often sculptured with a few prominent spiral lirae; body whorl sometimes having a few weak spiral lines. Aperture ovate-pyriform, lip complete, usually adnate, columellar lip slightly thickened; shell imperforate or narrowly umbilicate. Operculum ovate, inner side smooth. Ctenidial filaments about 40, pleated, rather small. Stomach with small posterior caecum. Radula with about 40 rows of teeth; length/ width of ribbon 430%. Dorsal edge of central radular teeth (Figure 7E) well indented, basal tongue U-shaped, central cusps narrowly pointed, lateral cusps 3–6; basal cusps 1 or 2, outer cusps poorly developed. Lateral teeth with 2 or 3 cusps on inner side and 3 or 4 cusps on outer side; outer wing strongly flexed, length 180% width of tooth face. Inner marginal teeth (Figure 9A) with 15–18 cusps, outer marginal teeth with 23–35 cusps.

Prostate gland small, bean-shaped, pallial section 33% of total length. Distal penis usually pigmented, swelling weak along inner edge, penial duct nearly straight (Figure 25B). Oviduct loop vertical or posterior-oblique, pigmented. Brood-pouch opening terminal, slightly muscularized; brooded embryos about 15. Albumen gland on right side of bursa copulatrix. Bursa copulatrix large for genus, narrowly ovate; seminal receptacle much smaller than bursa copulatrix, narrowly ovate. Sperm-duct opening to proximal portion of bursal duct. Sperm-tube opening to near middle of pallial cavity.

DISTRIBUTION.—Endemic to Ash Meadows, Amargosa River drainage, Nevada.

REMARKS.—This species is distinguished from other congeners by the flattening of the teleoconch whorls immediately below the suture (Figure 4F).

MATERIAL EXAMINED.—UNITED STATES. Nevada: Fairbanks Spring, Nye County, USNM 859151 (holotype), USNM 850299; Big Spring, Ash Meadows, Nye County, USNM 883304.

Tryonia cheatumi (Pilsbry, 1935)

Potamopyrgus cheatumi Pilsbry, 1935:91, fig. 4 [type locality, Phantom Lake, near Toyahvale, Reeves County, Texas].

Lyrodes cheatumi.—Berry, 1947:68 [reassignment].

Littoridina (Lyrodes) cheatumi.—Baker, 1964:171 [lectotype selection; reassignment].

Tryonia cheatumi.—Taylor, 1966b:196 [reassignment]; 1987:38–41, fig. 19, tables 43, 44 [placement in new subgenus Paupertryonia].

DIAGNOSIS.—Shell medium-sized, conical. Penial ornament of 2 distal papillae along inner edge.

DESCRIPTION.—Shell (Figure 22D) 2.8–4.2 mm tall. Males smaller than females (Taylor, 1987, table 43). Whorls, 4.75–6.0, weakly convex; teleoconch sometimes sculptured with weak spiral threads. Aperture ovate-pyriform, lip complete but very thin across parietal wall; shell imperforate or narrowly umbilicate. Operculum (Figure 6B) ovate, border of attachment area slightly thickened. Ctenidial filaments about 27, pleated. Stomach with very small posterior caecum. Radula with about 51 rows of teeth, length/width of ribbon 550%. Dorsal edge of central radular teeth slightly convex to indented, basal tongue U-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 4–6; basal cusps 1 or 2, outer cusps weakly to well developed. Lateral teeth (Figure 8B) with 3 cusps on inner side and 3 or 4 cusps on outer side; outer wing broad, well flexed, length 167% width of tooth face. Inner marginal teeth with 18–26 cusps, outer marginal teeth with 31–41 cusps.

Prostate gland small, ovate, pallial section 33% of total length. Distal penis blunt, pigmented, swelling along inner edge small, penial duct nearly straight (Figure 25C). Oviduct loop posterior-oblique, pigmented. Brood-pouch opening subterminal, slightly thickened; brooded embryos about 13. Albumen gland on right side of bursa copulatrix. Bursa copulatrix medium to large for genus, narrowly ovate; seminal receptacle much smaller than bursa copulatrix, ovate. Sperm-duct opening to base of bursal duct. Sperm-tube opening in posterior 33%–50% of pallial cavity.

DISTRIBUTION.—Drainage of Toyah Creek, Pecos River basin, Texas.

REMARKS.—Tryonia cheatumi is distinguished from other congeners by the absence of basal papillae on the penis (Figure 25C).

MATERIAL EXAMINED.—UNITED STATES. Texas: Phantom Lake, Reeves County, ANSP 16388 (lectotype); Phantom Lake spring, Reeves County, USNM 883952, USNM 883955, USNM 883957.

Tryonia circumstriata (Leonard and Ho, 1960)

Calipyrgula circumstriata Leonard and Ho, 1960:125–127, pl. 12: figs. 1–3 [type locality, late Pleistocene terrace deposits in right bank of Pecos River, one-fourth mile [0.4 km] above mouth of Independence Creek, on Chandler Ranch, Terrell County, Texas].

Tryonia circumstriata.—Taylor, 1966b: 196–197 [reassignment].

Tryonia stocktonensis Taylor, 1987:37–38, fig. 18, table 42 [type locality. Diamond Y Draw, nine miles [14.4 km] north of Fort Stockton and 0.5 mile [0.8 km] west of State Highway 18, Pecos County, Texas].—Hershler and Thompson, 1992:110 [synonymized with Tryonia circumstriata].

DIAGNOSIS.—Shell medium- to large-sized, conical. Penial ornament of 2 distal papillae along inner edge and single, large, basal papillae on inner and outer edges.

DESCRIPTION.—Shell (Figures 4H, 22E,F) 3.0–5.5 mm tall. Shell apex shown in Figure 5A,C. Whorls, 5.0–7.0, medium convexity; teleoconch almost smooth or sculptured with 10–15 regularly spaced spiral lirae, sometimes crossed by weak collabral ribs. Aperture ovate-pyriform, lip complete, thin, adnate; shell imperforate or narrowly umbilicate. Operculum ovate, border of attachment area weakly thickened (Figure 6D). Ctenidial filaments about 25, pleated. Stomach without posterior caecum. Radula with about 36 rows of teeth; length/width of ribbon 450%. Dorsal edge of central teeth (Figure 7F) weakly indented, basal tongue broadly V-shaped, central cusps broadly triangular, lateral cusps 4–6; basal cusps 2 or 3, outer cusps sometimes weakly developed. Lateral teeth with broad central cusp, 3–5 cusps on inner side and 5–7 cusps on outer side; outer wing strongly flexed, length 170% width of tooth face. Inner marginal teeth (Figure 9D) with 23–31 cusps, outer marginal teeth with 28–39 cusps.

Prostate gland large, bean-shaped, pallial section 33%–50% of total length. Terminal portion of penis blunt, pigmented, pronounced swelling along inner edge, penial duct undulating (Figure 25D). Oviduct loop posterior-oblique, pigmented. Brood-pouch opening terminal, slightly muscularized, brooded embryos 7–10. Albumen gland on right side of bursa copulatrix. Bursa copulatrix large for genus, narrowly ovate; seminal receptacle much smaller than bursa copulatrix, globular. Sperm-duct opening to base of bursal duct. Sperm-tube opening in posterior one-third of pallial cavity.

DISTRIBUTION.—Pecos River drainage, Texas.

REMARKS.—This species is distinguished from T. cheatumi (the only other congener present in the Pecos River drainage) by its narrower, more strongly sculptured shell and by its more numerous penial papillae. Extant populations are variable in sculpture and include weakly lirate and nearly smooth-shelled individuals (Figure 22F), but nonetheless they intergrade completely with Pleistocene material, which was the basis for earlier placement of T. stocktonensis in synonymy with T. circumstriata (Hershler and Thompson, 1992).

MATERIAL EXAMINED.—UNITED STATES. Texas: Diamond Y Draw, Pecos County, LACM 2090 (holotype, Tryonia stocktonensis), USNM 854092 (paratypes, Tryonia stocktonensis), USNM 883406, USNM 883958; Diamond Y Spring, Pecos County, USNM 892020; late Pleistocene deposits along Pecos River, Terrell County (holotype, Calipyrgula circumstriata), USNM 440734.

Tryonia clathrata Stimpson, 1865

Tryonia clathrata Stimpson, 1865:54, pl. 8: fig. 1 [type locality, basin of the Colorado Desert],—Baker, 1964:172 [lectotype selection],—Hershler and Thompson, 1987, figs. 1, 2, 11–15, 19, 21–23; 1992, figs. 71a,c-e, 72.—Hershler, 1999:331–332. fig. 14 [distribution map].

DIAGNOSIS.—Shell medium- to large-sized, conical. Penial ornament of 4 medial to proximal and 1 basal papillae along inner edge, and occasional basal papilla arising from near midline (rather than from penis edge).

DESCRIPTION.—Shell (Figures 4E, 22G) 2.9–7.0 mm tall. Whorls, 5.75–8.75, weakly convex; collabral sculpture varying from low ribs to almost spinose projections, beginning at about 1.5 whorls, becoming strong at whorl 3.0; sculptural elements about 15 on body whorl. Aperture ovate-pyriform, lip complete in larger specimens, thin, adnate; shell imperforate or narrowly umbilicate. Operculum (Figure 6C,F) ellipsoidal, nucleus highly eccentric, inner side smooth. Ctenidial filaments about 42, pleated. Stomach with small posterior caecum. Radula with about 56 rows of teeth; length/width of ribbon 550%. Dorsal edge of central radular teeth (Figure 7D) weakly indented, basal tongue U-shaped, central cusps narrowly pointed, lateral cusps 6–8, basal cusps 2 or 3. Lateral teeth (Figure 8A) with 3 or 4 cusps on inner side and 4–6 cusps on outer side; outer wing strongly flexed, length 150% width of tooth face. Inner marginal teeth with 22–29 cusps, outer marginal teeth with 28–32 cusps.

Prostate gland large, bean-shaped, pallial section 33% of total length. Distal penis pigmented, well-developed swelling on inner edge, penial duct gently undulating (Figure 25E). Oviduct loop posterior-oblique, pigmented. Brood-pouch opening terminal, slightly muscular; brooded embryos about 15. Albumen gland on right side of and partly dorsal to bursa copulatrix. Bursa copulatrix large for genus, ovate; seminal receptacle much smaller than bursa copulatrix, ovate. Sperm-duct opening to proximal portion of bursal duct. Sperm-tube opening in posterior 33%–50% of pallial cavity.

DISTRIBUTION.—White River trough, southern Nevada.

REMARKS.—Tryonia clathrata is distinguished from other congeners by its strong collabral shell sculpture (Figure 4E), ellipsoidal operculum (Figure 6C,F), and more numerous papillae on the inner edge of the penis (Figure 25E). Hershler (1999) reviewed the literature concerning the type locality of this species, which should be attributed to the White River drainage of southern Nevada.

MATERIAL EXAMINED.—UNITED STATES. Nevada: White River drainage, ANSP 27969 (lectotype); spring west of Oasis Spring, Moapa Valley, Clark County, USNM 850291, USNM 873192; six miles [9.6 km] northwest of Moapa, USNM 791488.

Tryonia elata Hershler and Sada, 1987

Tryonia elata Hershler and Sada, 1987:831, figs. 39b, 42c, 44, 53e-h, 56, table 2 [type locality. Point of Rocks Springs, Ash Meadows, Nye County, Nevada].—Hershler, 1989, table 2.

DIAGNOSIS.—Shell small- to medium-sized, narrow-conic. Penial ornament of 2 distal and 1 basal papillae along inner edge.

DESCRIPTION.—Shell (Figures 4I, 22H) 1.8–2.9 mm tall. Whorls, 5.25–6.75, medium convexity, sutures impressed. Aperture ovate, lip complete, slightly thickened, often separated from body whorl; umbilicus rimate. Operculum ovate, inner side smooth. Ctenidial filaments about 17, without pleats. Stomach without posterior caecum. Radula with about 34 rows of teeth; length/width of ribbon 510%. Dorsal edge of central radular teeth weakly indented, basal tongue U-shaped, central cusps narrowly pointed, lateral cusps 5 or 6; basal cusps 1 or 2, outer cusps weakly developed. Lateral teeth (Figure 8D) with 3 or 4 cusps on inner side and 4 or 5 cusps on outer side; outer wing weakly flexed, length 150% width of tooth face. Inner marginal teeth (Figure 9C) with 19–22 cusps, outer marginal teeth with 23–28 cusps.

Prostate gland very small, subglobose, pallial section very short. Distal penis pigmented, without swelling along inner edge, penial duct nearly straight (Figure 25F). Oviduct loop posterior-oblique, pigmented. Brood pouch not extending into posteriorly folded section of glandular oviduct; opening of brood-pouch terminal, slightly thickened; brooded embryos about 4. Albumen gland extending posterior to bursa copulatrix. Bursa copulatrix large for genus, ovate; seminal receptacle much smaller than bursa copulatrix, ovate. Sperm-duct opening to proximal portion of bursal duct. Sperm tube long, opening alongside brood-pouch opening.

DISTRIBUTION.—Endemic to Ash Meadows, Amargosa River basin, Nevada.

REMARKS.—Tryonia elata is distinguished from other congeners by the combination of small size and narrow-conic shell (Figures 4I, 22H). This species also is unique within the genus in lacking a posteriorly folded component of the brood pouch.

MATERIAL EXAMINED.—UNITED STATES. Nevada: Point of Rocks spring, Nye County, USNM 859159 (holotype), USNM 850309.

Tryonia ericae Hershler and Sada, 1987

Tryonia ericae Hershler and Sada, 1987:826–831, figs. 39c,d, 42f,i, 44, 53a-d, 54, 55, table 2 [type locality, North Scruggs Spring, Ash Meadows, Nye County, Nevada],—Hershler, 1989, table 2.

DIAGNOSIS.—Shell small, conical. Penial ornament of 2 distal and 1 basal to medial papillae along inner edge.

DESCRIPTION.—Shell (Figure 22I) 1.2–1.9 mm tall. Shell apex shown in Figure 5F. Whorls, 3.75–6.0, medium convexity, sutures impressed. Aperture ovate, lip complete, often slightly thickened all around, often separated from body whorl; umbilicus rimate to broadly open. Operculum ovate, whorl edges slightly flared on outer side. Ctenidial filaments about 14, without pleats. Stomach without posterior caecum. Radula with about 42 rows, posteriormost 12 rows weakly developed; length/width of ribbon 410%. Dorsal edge of central radular teeth weakly indented, basal tongue V-shaped, central cusps narrowly pointed, lateral cusps 5 or 6, basal cusps 2. Lateral teeth having 3 cusps on inner side and 4 or 5 cusps on outer side; outer wing weakly flexed, length 175% width of tooth face. Inner marginal teeth with 14–25 cusps, outer marginal teeth with 21–28 cusps.

Prostate gland very small, bean-shaped, pallial section 33% of total length. Distal penis pigmented, weak swelling along inner edge, penial duct with several weak undulations (Figure 26A). Oviduct loop posterior-oblique, pigmented. Brood-pouch opening terminal, slightly raised (Figure 3A); brooded embryos 1 or 2. Albumen gland on right side of bursa copulatrix. Bursa copulatrix large for genus, ovate; seminal receptacle much smaller than bursa copulatrix, globular. Sperm-duct opening to base of bursal duct. Sperm tube long, fused with brood-pouch opening.

DISTRIBUTION.—Endemic to Ash Meadows, Amargosa River basin, Nevada.

REMARKS.—This snail is distinguished from other congeners by its small size and conical shell with impressed sutures and frequently thickened aperture (Figure 22I). Tryonia ericae also is unique in the genus in that the female sperm tube and brood pouch are fused (Figure 3A) instead of opening separately.

MATERIAL EXAMINED.—UNITED STATES. Nevada: North Scruggs Spring, Nye County, USNM 859162 (holotype), USNM 850312.

Tryonia exigua (Morelet, 1851)

Melania exigua Morelet, 1851:23 [type locality, Lake Petén Itza (=Laguna de Flores), Petén Department, Guatemala] [not Melania exigua Conrad, 1855].

Melania minuta Brot, 1862:43 [unnecessary replacement name for Melania exigua Morelet, 1851].

Tryonia exigua.—Fischer and Crosse, 1891:275–276, pl. L: fig. 2, 2a, 2b [reassignment],—Taylor, 1966b: 197.

Paludestrina exigua.—Goodrich and van der Schalie, 1937:36 [reassignment].

Pyrgophorus exiguus.—Hershler and Thompson, 1992:93 [reassignment].

DIAGNOSIS.—Shell medium- to large-sized, conic to elongate-conic. Penial ornament of 2 or 3 distal and 1 basal papillae on inner edge.

DESCRIPTION.—Shell (Figures 4J, 23A) 4.2–7.3 mm tall. Whorls, 6.5–7.5, weakly convex; teleoconch sculptured with narrow costae (about 13 per whorl); sculpture beginning at 2.5 whorls, weakening on body whorl. Aperture narrowly ovate, lip complete, usually thickened all around, broadly adnate; shell imperforate or narrowly umbilicate. Operculum ovate, border of attachment area often thickened. Ctenidial filaments about 30, pleated. Posterior caecum of stomach large for genus. Radula with about 50 rows of teeth, the posteriormost 14 incompletely developed; length/width of ribbon 525%. Dorsal edge of central radular teeth straight or weakly indented. Basal tongue broadly V-shaped, central cusps elongate, narrowly pointed, lateral cusps 3 or 4, basal cusps 2 or 3. Lateral teeth having 3–5 cusps on inner side and 4–6 cusps on outer side; outer wing weakly flexed, length 180% width of tooth face. Inner marginal teeth with 19–26 cusps, outer marginal teeth with 19–29 cusps.

Prostate gland small, ovate, entirely visceral. Distal penis without pigment, well-developed swelling along inner edge, penial duct undulating (Figure 26B). Oviduct loop anterior-oblique, pigment not evident. Brood-pouch opening terminal, forming well-developed sphincter; brooded embryos about 17, mostly packed into posteriorly folded section of duct. Albumen gland protruding slightly posterior to bursa copulatrix. Sperm pouches minute, ovate; seminal receptacle slightly smaller than bursa copulatrix. Sperm-duct opening to base of bursal duct. Sperm-tube opening in posterior 33%–50% of pallial cavity.

DISTRIBUTION.—Lake Petén Itza, interior drainage, Guatemala.

REMARKS.—Tryonia exigua is distinguished from other congeners by the combination of its large size, collabral shell sculpture (Figure 4J), and very small penial papillae (Figure 26B).

An adult syntype with complete aperture and well-developed collabral shell sculpture is designated as the lectotype for Melania exigua (BMNH 1893.2.4.1769). This species has been sparsely treated in the literature, which, along with its varied generic placement, is indicative of it only having been studied previously as empty shells. USNM 874034 (from the northeast corner of Lake Petén Itza), however, includes live-collected specimens of a narrow-shelled snail consistently sculptured with collabral costae that closely corresponds to the type series of Melania exigua and to the figures of Morelet's material provided by Fischer and Crosse (1891). The anatomy of this snail clearly conforms to Tryonia. (Body pigment has probably faded in this 1978 sample.) Note that the broad-shelled specimen figured by Reeve (1861, pl. LVIII, species 460) more closely resembles the species of Pyrgophorus that also lives in this lake.

MATERIAL EXAMINED.—GUATEMALA. Petén: Lake Petén Itza, BMNH 1893.2.4.1769 (lectotype), BMNH 1893.2.4.1770–1773 (paralectotypes); northeast corner of Lake Petén Itza, USNM 874034.

Tryonia gilae Taylor, 1987

Tryonia gilae Taylor, 1987:36–37, fig. 17, tables 40, 41 [type locality, unnamed spring on north side of Gila River about two miles [3.2 km] north of Bylas, in T 3S, R 22E, 25,000 feet [7750 m] west and 15,500 feet [4800 m] north of the township line, Graham County, Arizona].

Tryonia gilae Hershler in Hershler and Landye, 1988:43, 47–49, 58 [synonymized with T. gilae Taylor noted], figs. 14c,f, 39a-e, 40, 41a-c, 42, 43d-i, 44, 45, 46a, 47b, table 2 [type locality, small spring near Bylas, Graham County, Arizona].

DIAGNOSIS.—Shell small- to medium-sized, conical. Penial ornament of 2 small distal papillae on inner edge and 1 basal papilla on outer edge.

DESCRIPTION.—Shell (Figures 4C, 23B,C) 1.6–3.4 mm tall. Males smaller than females (Taylor, 1987, table 40). Shell apex shown in Figure 5E. Whorls, 4.0–6.0, low to medium convexity; teleoconch often sculptured with weak spiral striae. Aperture ovate, lip complete, thin, adnate or slightly disjunct; shell imperforate or narrowly umbilicate. Operculum ovate, inner side smooth. Ctenidial filaments about 21, pleated. Stomach with very small posterior caecum. Radula with about 42 rows of teeth; length/width of ribbon 470%. Dorsal edge of central radular teeth slightly indented, basal tongue broadly V-shaped, central cusps narrowly pointed, lateral cusps 4–6, basal cusps 2. Lateral teeth having 4 or 5 cusps on inner side and 4–6 cusps on outer side; outer wing well flexed, length 200% width of tooth face. Inner marginal teeth with 21–26 cusps, outer marginal teeth (Figure 10A) with 25–29 cusps.

Prostate gland very small, globose, often entirely visceral. Distal penis pigmented, without swelling along inner edge, penil duct straight (Figure 26C). Oviduct loop anterior-oblique, pigmented. Brood-pouch opening terminal, forming small papilla; brooded embryos 4 or 5. Albumen gland on right side of bursa copulatrix. Bursa copulatrix small, ovate; seminal receptacle a little smaller than bursa copulatrix, ovate. Sperm-duct opening to proximal portion of bursal duct. Sperm-tube opening in posterior 33% of pallial cavity.

DISTRIBUTION.—Upper Gila River basin, Arizona.

REMARKS.—This snail is distinguished from other congeners by the combination of small size of the penial papillae and the absence of a distal swelling on the inner edge of the penis (Figure 26C).

MATERIAL EXAMINED.—UNITED STATES. Arizona: unnamed spring on north side of Gila River about two miles [3.2 km] north of Bylas, Graham County, LACM 2187 (holotype, Tryonia gilae Taylor), USNM 854074 (paratypes, Tryonia gilae Taylor); small spring near Bylas, Graham County, USNM 859059 (holotype, Tryonia gilae Hershler); Cold Springs, Graham County, USNM 847253; spring northwest of Bylas, Graham County, USNM 883956; spring slightly north of above, USNM 883267.

Tryonia hertleini (Drake, 1956)

Lyrodes hertleini Drake, 1956:44–46, pl. 15 [type locality, springs at Las Palomas, Chihuahua, Mexico].

Fontelicella hertleini.—Taylor, 1975:95 [reassignment].

Tryonia hertleini.—Hershler and Thompson, 1992:110 [reassignment].

DIAGNOSIS.—Shell medium-sized, conical. Penial ornament of 2 distal and 1 massive basal papillae on inner edge.

DESCRIPTION.—Shell (Figures 4D, 23D) 2.5–3.2 mm tall. Whorls, 4.75–5.5, medium convexity; teleoconch sculptured with a few spiral lines. Aperture ovate, lip complete, thin, adnate; shell imperforate or narrowly umbilicate. Operculum ovate, inner side smooth. Ctenidial filaments about 33, pleated. Stomach without posterior caecum. Radula with about 36 rows of teeth, the posteriormost 10 weakly developed; length/width of ribbon 460%. Dorsal edge of central radular teeth weakly indented, basal tongue broadly V-shaped, central cusps narrowly pointed, lateral cusps 4 or 5, basal cusps 2. Lateral teeth with 2 cusps on inner side and 4 or 5 cusps on outer side; outer wing strongly flexed, length 260% of tooth-face width. Inner marginal teeth with 15–17 cusps, outer marginal teeth with 26–32 cusps.

Prostate gland large, thick, subglobose, pallial section 33% of total length. Distal penis without pigment, well-developed swelling along inner edge, penial duct undulating (Figure 26D). Oviduct loop anterior-oblique, pigmented. Brood-pouch opening terminal, slightly thickened; brooded embryos about 18, forming 2 rows in posteriorly folded section. Albumen gland on right side of bursa copulatrix. Bursa copulatrix large for genus, ovate; seminal receptacle much smaller than bursa copulatrix, ovate. Sperm-duct opening to distal portion of bursal duct. Sperm-tube opening to posterior 33% of pallial cavity.

DISTRIBUTION.—Las Palomas, interior drainage of northeast Mexico. This species may be extinct because its only known locality dried more than 25 years ago (Landye in Hershler, 1994).

REMARKS.—Tryonia hertleini is distinguished from other congeners by the massive basal papilla on the inner side of the penis (Figure 26D). The highly elongate outer wing of the lateral radular teeth of this species also is unique in the genus.

The holotype of this species has a broken aperture, so a paratype was figured instead (Figure 23D). Note that the UMMZ alcohol-preserved material studied was collected during an ichthyological survey and was not relaxed.

MATERIAL EXAMINED. MEXICO. Chihuahua: springs at Las Palomas, CAS 64918 (holotype), CAS 64919 (paratypes), USNM 600498 (paratypes); spring-fed pond 3.6 miles [5.8 km] south of Las Palomas, UMMZ uncataloged.

Tryonia imitator (Pilsbry, 1899)

Paludestrina imitator Pilsbry, 1899:124 [type locality, Santa Cruz, California].—Taylor, 1966b: 197.

Paludestrina curta Arnold, 1903:305 [type locality, San Pedro bluffs (California), Upper San Pedro Series (Pleistocene)].—Woodring et al., 1946:66 [synonymized with Hydrohiaprotea=Tryonia protea].—Taylor, 1966b:197 [synonymized with T. imitator].

Hydrobia imitator.—Berry, 1948:59 [reassignment].

Amnicola imitator.—Baily and Baily, 1952:51 [reassignment].

Tryonia imitator.—Taylor, 1966b:197 [reassignment]; 1981:153 [distribution].

DIAGNOSIS.—Shell medium- to large-sized, ovate-conic. Penial ornament of 2 distal and 1 basal papillae on inner edge.

DESCRIPTION.—Shell (Figure 23E,F) 2.5–5.5 mm tall. Shell apex shown in Figure 5B. Whorls, 4.25–6.0, medium convexity, teleoconch sculptured with 10–15 strong spiral lines interspersed between weaker threads. Aperture ovate, lip complete, thin, adnate; umbilicus rimate. Operculum ovate, inner side with weak rim along border. Ctenidial filaments about 35, pleated. Stomach with small posterior caecum. Radula with about 45 rows of teeth, length/width of ribbon 580%. Lateral margins of central radular teeth weakly flared (teeth almost square), dorsal edge medium indented, basal tongue slightly convex to V-shaped, central cusp broad, spoon-like, lateral cusps, 6–9, basal cusps 1 or 2, weakly developed. Lateral teeth (Figure 8C) having 3 or 4 cusps on inner side and 5–7 cusps on outer side; outer wing well flexed, length 150% of tooth-face width. Inner marginal teeth with 21–25 cusps, outer marginal teeth with 26–33 cusps.

Prostate gland small, ovate, pallial section 33% of total length, pallial vas deferens broad. Distal penis pigmented, well-developed swelling along inner edge, penial duct weakly undulating (Figure 26E). Oviduct loop anterior-oblique, pigmented. Brood-pouch opening subterminal, raised (Figure 3C); brooded embryos 25 to 30. Albumen gland largely posterior to bursa copulatrix. Bursa copulatrix small, ovate, pigmented; seminal receptacle a little smaller than bursa copulatrix, ovate or elongate (Figure 3D). Sperm-duct opening to distal portion of bursal duct. Sperm-tube opening in posterior 33% of pallial cavity.

DISTRIBUTION.—Southern California coast.

REMARKS.—This species is distinguished from closely similar T. salina by its typically larger, broader shell and weaker spiral sculpture. Tryonia imitator also is unique in the genus in having a pigmented bursa copulatrix (Figure 3D).

MATERIAL EXAMINED.—UNITED STATES. California: Pleistocene deposits, San Pedro Bluffs, USNM 162542 (holotype, Paludestrina curta); Santa Cruz, Santa Cruz County, ANSP 62670 (lectotype, Paludestrina imitator); Morro Bay, San Luis Obispo County, USNM 892057.

Tryonia margae Hershler, 1989

Tryonia margae Hershler, 1989:202–205, figs. 48–50, 51a, 52, table 2 [type locality, (upper) warm spring on limestone bench, Grapevine Springs, Death Valley, Inyo County, California].

DIAGNOSIS.—Shell small- to medium-sized, conic to turriform. Penial ornament of 2 distal and 1 basal papillae on inner edge and an occasional basal papilla on outer edge.

DESCRIPTION.—Shell (Figures 4L, 23G) 1.5–3.5 mm tall. Whorls, 4.5–8.5, weakly convex, sutures impressed. Aperture ovate, lip complete, thin, adnate or slightly disjunct; shell imperforate or narrowly umbilicate. Operculum ovate, inner side smooth. Ctenidial filaments about 28, without pleats. Stomach without posterior caecum. Radula with about 37 rows of teeth, length/width of ribbon 390%. Dorsal edge of central radular teeth weakly indented, basal tongue U-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 4 or 5, basal cusps 1 or 2. Lateral teeth having 3 cusps on inner side and 4 or 5 cusps on outer side; outer wing strongly flexed, length 167% tooth-face width. Inner marginal teeth with 20–25 cusps, outer marginal teeth (Figure 10C) with 25–31 cusps.

Prostate gland small, thick, bean-shaped, pallial section about 33% of total length. Distal penis pigmented, narrow swelling along inner edge, penial duct weakly undulating (Figure 27A). Oviduct loop posterior-oblique. Brood-pouch opening terminal, slightly thickened; brooded embryos 3 or 4. Albumen gland on right side of bursa copulatrix. Bursa copulatrix large, narrowly ovate; seminal receptacle much smaller than bursa copulatrix, ovate. Sperm-duct opening to proximal portion of bursal duct. Sperm-tube opening in posterior 33% of pallial cavity.

DISTRIBUTION.—Endemic to type locality area, Amargosa River basin, California.

REMARKS.—Tryonia margae is distinguished from other congeners by the combination of small size and narrow shell.

MATERIAL EXAMINED.—UNITED STATES. California: (upper) warm spring on limestone bench, Grapevine Springs, Inyo County, USNM 860408 (holotype), USNM 857952 (paratypes); Grapevine Springs, Inyo County, USNM 854599, USNM 883308.

Tryonia monitorae Hershler, 1999

Tryonia monitorae Hershler, 1999:332, 334, figs. 3D, 13D–G, 14, 15, table 1 [type locality, Hot Springs, Potts Ranch, Monitor Valley, Nye County, Nevada].

DIAGNOSIS.—Shell medium-sized, elongate-conic. Penial ornament of 2 distal and 1 basal papillae on inner edge and 1 basal papilla arising between midline and outer edge.

DESCRIPTION.—Shell (Figure 23H) 3.0–4.6 mm tall. Whorls, 6.25–7.5, weakly to moderately convex; spiral threads sometimes prominent on shells retaining periostracum. Aperture ovate, lip usually complete, thin, adnate; shell imperforate. Operculum ovate, inner side smooth. Ctenidial filaments about 35, pleated. Stomach without posterior caecum. Radula with about 47 rows of teeth; length/width of ribbon 590%. Dorsal edge of central teeth slightly indented, basal tongue V-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 5–7, basal cusps 1 or 2. Lateral teeth with 4 cusps on the inner side and 5 or 6 cusps on the outer side; outer wing well flexed, length 175% width of tooth face. Inner marginal teeth with 19–25 cusps, outer marginal teeth with 22–27 cusps.

Prostate gland small, ovate, pallial section slightly less than 33% of total length. Distal penis pigmented, well-developed swelling on inner edge, penial duct undulating for most of length (Figure 27B). Oviduct loop anterior-oblique, pigmented. Brood-pouch opening terminal, slightly muscularized; brooded embryos about 12. Albumen gland on right side of bursa copulatrix. Bursa copulatrix large, ovate; seminal receptacle much smaller than bursa copulatrix, ovate. Sperm-duct opening to distal portion of bursal duct. Sperm-tube opening in posterior 33% of pallial cavity.

DISTRIBUTION.—Endemic to Monitor Valley, Great Basin, Nevada.

REMARKS.—This snail is distinguished from closely similar T. margae by its larger size and more rounded shell whorls.

MATERIAL EXAMINED.—UNITED STATES. Nevada: Hot Springs, Potts Ranch, USNM 892046 (holotype), USNM 860760 (paratypes).

Tryonia porrecta (Mighels, 1845), new combination

Paludina porrecta Mighels, 1845:22 [type locality, Oahu (Hawaii)].—Küster, 1852:34–35, pl. 7: figs. 25, 26.

Amnicola protea Gould, 1855:129–130 [type locality, Colorado Desert (Gran Jornado)].—Gould, 1857:332, pl. XI: figs. 6–9.

Melania exigua Conrad, 1855:269 [type locality, Colorado desert, California].—Binney, 1865:72, fig. 141 [synonymized with T. protea].—Baker, 1964:172 [lectotype selection; transferred to Tryonia].

Hydrobia porrecta.—Frauenfeld, 1863:1024 [reassignment].

Tryonia protea.—Binney, 1865:71–72, figs. 140, 142.—Bequaert and Miller, 1973:213 [emendation of type locality to near Salton View, Riverside County, California].—Taylor, 1981:153–154 [distribution]; 1985, fig. 35 [distribution map].—Hershler, 1999:334–335, fig. 14 [distribution map], table 2.

Bythinella protea.—Stearns, 1893:278–281 [reassignment].

Paludestrina porrecta.—Sykes, 1900:396 [reassignment].

Paludestrina protea.—Stearns, 1901:277–284, fig. 1, pls. XIX–XXI [reassignment].

Hydrobia protea.—Wenz, 1922:153 [reassignment].

Pyrgulopsis imminens Taylor, 1950:28, figs. 1–3 [type locality, shore of Salton Sea by Fish Springs [=Desert Shores], Imperial County, California].—Hershler and Thompson, 1992:111 [synonymized with T. protea].

Pyrgulopsis blakeana Taylor, 1950:30–31, figs. 4–6 [type locality, shore of Salton Sea by Fish Springs, Imperial County, California]; 1966b:196 [synonymized with T. protea].

Pyrgulopsis cahuillarum Taylor, 1950:31–32, fig. 7 [type locality, fifty yards [46 m] northeast of the so-called Fish Traps, 7.9 miles [12.6 km] west of Mecca, Riverside County, California]; 1966b: 196 [synonymized with T. protea].

DIAGNOSIS.—Shell medium- to large-sized, conical. Males absent.

DESCRIPTION.—Shell (Figures 4K, 24A–F) 2.75–7.4 mm tall. Whorls, 5.0–7.5, almost flat to well rounded, sometimes having pronounced subsutural angulations. Teleoconch smooth or sculptured with about 10 regularly spaced spiral ridges (beginning on second whorl) and/or weak collabral ridges (about 10 on last 0.5 whorl), sometimes producing cancellate appearance. Aperture ovate, lip complete, usually thin, adnate or disjunct; shell imperforate or narrowly umbilicate. Operculum ovate, border of attachment area slightly thickened. Ctenidial filaments about 24, without pleats. Posterior caecum of stomach large for genus. Radula with about 45 rows of teeth, length/width of ribbon 500%. Dorsal edge of central radular teeth (Figure 7C) medium indented, basal tongue U-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 4 or 5, basal cusps 2 or 3. Lateral teeth with 4 or 5 cusps on inner side and 6 or 7 cusps on outer side, outer wing strongly flexed, length 160% width of tooth face. Inner marginal teeth (Figure 9B) with 32–37 cusps, outer marginal teeth with 30–38 cusps.

Oviduct loop anterior-oblique, weakly pigmented. Brood-pouch opening terminal, slightly thickened; brooded embryos 11–20. Albumen gland extending slightly posterior to bursa copulatrix. Bursa copulatrix small, elongate. Seminal receptacle slightly smaller than bursa copulatrix, elongate, darkly pigmented; duct slightly longer than body of seminal receptacle. Sperm-duct opening to distal portion of bursal duct. Sperm-tube opening in posterior one-third of pallial cavity.

DISTRIBUTION.—Lower Colorado River basin, Great Basin, and Hawaii. Hawaiian populations may have been introduced (Athens and Ward, 1993; Cowie, 1997), but this would have to have occurred prior to 1845.

REMARKS.—In the absence of information on the insertion of the visceral vas deferens into the prostate gland (which is not available for this parthenogenetic snail), this species is assigned to Tryonia on the basis of its coiled sperm duct, which further distinguishes this genus from other Tryonia-like snails. Note that in the phylogenetic analysis of mtDNA sequences this snail grouped within the “true” Tryonia clade (Hershler, Liu, and Mulvey, 1999). Tryonia porrecta is distinguished from other congeners by the absence of males. This snail also is unique within the genus in having a darkly pigmented seminal receptacle.

The type material for Paludina porrecta has been assumed to be lost (Cowie, 1997). Although most of Mighel's collection, which was reposited at the Portland (Maine) Society of Natural History, was destroyed by fire during the middle part of the 18th century (Norton, 1927), types for some of the species that he described were distributed to other institutions, and some Hawaiian material was sent to private collector Hugh Cuming (Johnson, 1949). The Cuming Collection (now housed in The Natural History Museum, London) contains a six-specimen lot of Paludina porrecta, one of which is shown in Figure 24A. The handwriting on the original label of this lot is suggestive of that of Mighels (fide Johnson, 1949:215), and the BMNH label lists this as possible type material, but there is no further indication that these shells represent part of the type series. A lectotype of Amnicola protea (Figure 24B) is designated that closely resembles the specimens figured by Gould (1857) and that was in the best condition of the seven syntypes (several of which are highly worn).

The close similarity between Paludina porrecta and Tryonia protea has been noted previously (Cowie, 1995; Hershler in Cowie, 1997). The possible syntype lot of P. porrecta and other samples from the Hawaiian Islands closely conform in all respects to western North American snails referred to T. protea. Alcohol-preserved material of the Hawaiian snail (BPMNH uncat.) also conforms closely to T. protea in female anatomical details (and in the absence of males), hence these taxa are treated as synonymous.

Two of the three species of Pyrgulopsis that Taylor (1950) described from the Salton Trough were subsequently treated by him as synonyms of T. protea (e.g., Taylor, 1981). The third species (P. imminens) is distinguished by its thicker shell and more angular aperture, which presumably led Taylor (1985, fig. 17) to retain it in the genus Pyrgulopsis. Alternatively this feature may be viewed as the endpoint of a continuum of variation within T. porrecta (see Figure 24D–F) The impressive shell variation within broadly distributed T. porrecta was well described by Stearns (1901). Although Taylor (1966a:53–54) suggested that extant forms referable to T. protea may represent several species, recognition of a single species nonetheless is indicated by the invariant anatomy of these animals, and by the genetic uniformity of populations in the American Southwest (Hershler, Liu, and Mulvey, 1999; Hershler, Mulvey, and Liu, 1999; Mulvey and Hershler, Ms).

MATERIAL EXAMINED.—UNITED STATES. California: Colorado Desert, ANSP 27965 (lectotype and paralectotypes, Melania exigua); shore of Salton Sea by Fish Springs, Imperial County, SBMNH 35497 (holotype, Pyrgulopsis imminens), SBMNH 35500 (holotype, Pyrgulopsis blakeana)., near Salton View, Riverside County, USNM 120174 (lectotype, Amnicola protea), USNM 860867 (paralectotypes, Amnicola protea); Hunters Spring, Riverside County, USNM 874194; 7.9 miles [12.6 km] west of Mecca, Riverside County, SBMNH 35503 (holotype, Pyrgulopsis cahuillarum); Oasis Spring, Riverside County, USNM 854744, USNM 873441. Hawaii: Waiakea, BPMNH uncat., Oahu, BMNH 1995123.

Tryonia quitobaquitae Hershler in Hershler and Landye, 1988

Tryonia quitobaquitae Hershler in Hershler and Landye, 1988:50, figs. 39f-h, 41d–f, 43a–c, 46a, 47a, table 2 [type locality, Quitobaquito Springs, Organ Pipe National Monument, Pima County, Arizona].

DIAGNOSIS.—Shell small, conical. Penial ornament of 1 medial to distal and 1 basal papilla on inner edge.

DESCRIPTION.—Shell (Figures 4B, 24G) 1.4–2.1 mm tall. Shell apex shown in Figure 5D. Whorls, 3.5–4.5, medium convexity, shoulders well developed; teleoconch occasionally sculptured with weak spiral lines. Aperture ovate, lip complete, thin, adnate or disjunct; shell imperforate or narrowly umbilicate. Operculum ovate, inner side smooth. Ctenidial filaments about 22, pleated. Stomach without posterior caecum. Radula with about 46 rows of teeth, length/width of ribbon 540%. Dorsal edge of central radular teeth medium indented, basal sockets V-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 4–6, basal cusps 1. Lateral teeth having 3 cusps on inner side and 3–5 cusps on outer side; outer wing well flexed, length 167% width of tooth face. Inner marginal teeth with 20–23 cusps, outer marginal teeth with 26–31 cusps.

Prostate gland small, ovate, almost entirely visceral. Distal penis without pigment, prominent swelling on inner edge, penial duct sometimes undulating proximally (Figure 27C). Distal penial papilla smaller than basal unit. Oviduct loop posterior-oblique, pigment not evident. Brood-pouch opening terminal, slightly muscularized; brooded embryos about 10. Albumen gland on right side of bursa copulatrix. Bursa copulatrix small, narrowly ovate; seminal receptacle slightly smaller than bursa copulatrix, elongate, with rather long duct. Sperm-duct opening to base of bursal duct. Sperm-tube opening in posterior 33% of pallial cavity.

DISTRIBUTION.—Endemic to the type locality area, Rio Sonoyta basin, interior drainage, Arizona.

REMARKS.—This snail is distinguished from other congeners by its unique pattern of penial ornament, consisting of two papillae along the inner edge (Figure 27C). Note that the body pigment may have faded in the old alcohol material studied.

MATERIAL EXAMINED.—UNITED STATES. Arizona: Quitobaquito Springs, Pima County, USNM 859061 (holotype), USNM 847256.

Tryonia rowlandsi Hershler, 1989

Tryonia rowlandsi Hershler, 1989:211–215, figs. 51b, 52, 59, 60, table 2 [type locality, Grapevine Springs, (upper) warm spring on limestone bench, Inyo County, California].

DIAGNOSIS.—Shell small- to medium-sized, conical. Penial ornament of 1 distal and 1 basal papilla on inner edge and 1 medial papilla on outer edge.

DESCRIPTION.—Shell (Figure 24H) 1.7–2.3 mm tall. Whorls, 4.0–4.75, well-rounded, sutures impressed; upper teleoconch whorls sculptured with a few, regularly spaced spiral lines. Aperture ovate, lip complete, usually thin, adnate; shell imperforate. Operculum ovate, inner side smooth. Ctenidial filaments about 18, without pleats. Stomach with very small posterior caecum. Radula with about 44 rows of teeth, length/width of ribbon 580%. Dorsal edge of central radular teeth (Figure 7A) well indented, basal tongue U-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 4–7, basal cusps 1. Lateral teeth with 3–5 cusps on inner side and 4 or 5 cusps on outer side; outer wing weakly flexed, length 150% of tooth-face width. Inner marginal teeth with 21–28 cusps, outer marginal teeth (Figure 10B) with 23–31 cusps.

Prostate gland small, subglobular, pallial section up to 33% of total length. Distal penis pigmented, without swelling on inner edge, penial duct nearly straight (Figure 27D). Oviduct loop posterior-oblique, pigmented. Brood-pouch opening terminal, muscularized; brooded embryos about 10. Albumen gland extending posterior to bursa copulatrix. Bursa copulatrix very small, ovate; seminal receptacle slightly smaller than bursa copulatrix, ovate. Sperm-duct opening to base of bursal duct. Sperm-tube opening in posterior 33% of pallial cavity.

DISTRIBUTION.—Endemic to type locality area, Amargosa River basin, California.

REMARKS.—Tryonia rowlandsi is distinguished from other congeners by the medial position of the papilla on the outer edge of the penis (Figure 27D).

MATERIAL EXAMINED.—UNITED STATES. California: Grapevine Springs, Death Valley, Inyo County, USNM 860409 (holotype), USNM 857953.

Tryonia salina Hershler, 1989

Tryonia salina Hershler, 1989:215–216, figs. 51e, 52, 61, 62, table 2 [type locality, spring in Cottonball Marsh, Inyo County, California].

DIAGNOSIS.—Shell medium-sized, ovate-conic. Penial ornament of 2 distal and 1 basal papillae on inner edge and 1 basal papilla on outer edge.

DESCRIPTION.—Shell (Figures 4A, 24I) 2.4–3.3 mm tall. Whorls, 4.5–5.25, highly convex, sutures impressed, teleoconch sculptured with numerous spiral lirae (about 15–18 on body whorl). Aperture broadly ovate, lip complete, thin, adnate or disjunct; umbilicus perforate. Operculum (Figure 6A) ovate, inner side smooth. Ctenidial filaments 28, pleated. Stomach with very small posterior caecum. Radula with about 44 rows of teeth, length/width of ribbon 550%. Dorsal edge of central radular teeth (Figure 7B) weakly indented, basal tongue weakly convex, central cusp broad, lateral cusps 4–7, basal cusps 2 or 3 (with occasional hint of fourth cusp). Lateral teeth having 3 or 4 cusps on inner side and 5–7 cusps on outer side; central cusp broad; outer wing strongly flexed, length 170% of tooth-face width. Inner marginal teeth with 23–25 cusps, outer marginal teeth with 26–32 cusps.

Prostate gland small, subglobular, pallial section <33% of total length. Distal penis pigmented, well-developed swelling on inner edge, penial duct weakly undulating (Figure 27E). Oviduct loop posterior-oblique, pigmented. Brood-pouch opening terminal, muscularized; brooded embryos 8. Albumen gland extending posterior to bursa copulatrix. Bursa copulatrix small, narrowly ovate; seminal receptacle a little smaller than bursa copulatrix, narrowly ovate. Sperm-duct opening to medial portion of bursal duct. Sperm-tube opening in posterior 33%-50% of pallial cavity.

DISTRIBUTION.—Endemic to the type locality area, Amargosa River basin, California.

REMARKS.—This species is distinguished from other congeners by its ovate-conic shell with large aperture and strong spiral sculpture (Figure 4A).

MATERIAL EXAMINED.—UNITED STATES. California: Cottonball Marsh, Inyo County, USNM 860410 (holotype), USNM 883326; spring in Cottonball Marsh, Inyo County, USNM 857998.

Tryonia variegata Hershler and Sada, 1987

Tryonia variegata Hershler and Sada, 1987:817, 819, 822–826, figs. 39e-g, 42b,e,g,h, 44–52, table 2 [type locality, Five Springs, Nye County, Nevada].—Hershler, 1989:216–219, 221, 222, figs. 51c, 52, 63, 64, table 2.

DIAGNOSIS.—Shell medium- to large-sized, conic to elongate-conic. Penial ornament of 2 or 3 distal and 1 basal papillae on inner edge and occasional basal papilla on outer edge.

DESCRIPTION.—Shell (Figure 24J) 2.8–7.5 mm tall. Whorls, 5.25–9.75, weakly convex, sometimes narrowly shouldered. Aperture pyriform, lip complete, slightly thickened, adnate; umbilicus rimate. Operculum (Figure 6E) ovate, inner side smooth. Ctenidial filaments 30, pleated. Stomach without posterior caecum. Radula with about 46 rows of teeth, length/width of ribbon 560%. Dorsal edge of central radular teeth medium indented, basal tongue U-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 4–6, basal cusps 2. Lateral teeth with 3 or 4 cusps on inner edge and 4 or 5 cusps on outer edge; outer wing weakly flexed, length 140% width of tooth face. Inner marginal teeth with 21–25 cusps, outer marginal teeth (Figure 10D) with 28–35 cusps.

Prostate gland small, bean-shaped, almost entirely visceral. Distal penis pigmented, swelling along inner edge weak or absent, penial duct weakly undulating (Figure 27F). Oviduct loop posterior-oblique, pigmented. Brood-pouch opening terminal, slightly muscularized; brooded embryos 4–11. Albumen gland extending slightly posterior to bursa copulatrix. Bursa copulatrix large, ovate; seminal receptacle much smaller than bursa copulatrix, globular. Sperm-duct opening to base of bursal duct. Sperm-tube opening in posterior 33%—50% of pallial cavity.

DISTRIBUTION.—Upper Amargosa River basin, California-Nevada.

REMARKS.—This species is distinguished from other congeners by its narrow, smooth, medium to large shell with evenly rounded whorls.

MATERIAL EXAMINED.—UNITED STATES. Nevada: Five Springs, Nye County, USNM 859166 (holotype), USNM 850314.

Genus Durangonella Morrison, 1945

Durangonella Morrison, 1945:18 [type species, Hydrobia seemani Frauenfeld, 1863, by original designation].

DIAGNOSIS.—Shell ovate-conic to turriform, smooth or with weak spiral sculpture. Penis ornamented with single nonglandular lobe; distal penis evenly rounded. Females ovoviviparous. Bursa copulatrix and seminal receptacle present; renal oviduct a small, unpigmented coil; sperm duct straight, opening to sperm tube in pallial cavity; sperm tube elongate.

DESCRIPTION.—Shell 2.3–5.8 mm tall, gray or clear, sexually dimorphic (males smaller; Hershler, 1985, table 33; Taylor, 1987, table 50), whorls 4.25–8.5. Periostracum thin. Protoconch small (<1.0 whorl), surface coarsely roughened; teleoconch smooth or weakly sculptured with spiral lines. Aperture small, inner lip complete across parietal wall, adnate or slightly disjunct, umbilicus rimate to broadly open. Operculum thin, ovate, multispiral, nucleus eccentric. Ctenidium well developed, connected to pericardium by short efferent vein; lateral surfaces of ctenidial filaments often pleated. Osphradium variably sized, narrow, almost centrally positioned along ctenidial axis. Kidney having small pallial portion, opening slightly muscularized. Pericardium bulging slightly into pallial cavity. Style sac about as long as stomach, posterior caecum small or absent (Hershler, 1985, fig. 36A). Rectum straight, anus near mantle edge. Radula with about 45–48 tooth rows, cusps generally narrowly pointed. Central teeth trapezoidal, with 1 or 2 pairs of basal cusps. Lateral teeth with enlarged central cusp, well-developed basal tongue; outer wing longer than width of tooth face. Inner and outer marginal teeth with numerous (1934) cusps borne largely or entirely on outer side; teeth with well-developed wings on outer edge and narrow, raised area extending from face to base (Figure 12C,D). Large testis of few (∼5) stalked lobes; seminal vesicle exiting from and coiled against left side of anterior portion of testis. Prostate gland large, banana-shaped, with about 50% of length in pallial roof. Visceral vas deferens opening to ventral edge of prostate gland slightly behind pallial wall, pallial vas deferens exiting from ventral edge of prostate gland at or just behind anterior edge. Penis medium-sized, rectangular, base slightly expanded; terminal portion densely ciliated, bulbous, without swelling on inner edge. Penial-duct opening through well-developed stylet. Penis ornamented with single, medial or distal, nonglandular lobe along inner edge. Penis pigmented with melanin distally, pigment also sometimes present on penial lobe. Females ovoviviparous, brooded young few to many (1–20), of different sizes (embryos having up to 2.0 shell whorls). Ovary a small sac (Hershler, 1985, fig. 36A). Glandular oviduct large, mostly consisting of thin-walled brood pouch, with a well-developed posterior fold, anterior opening muscular. Albumen gland very small relative to brood pouch (Hershler, 1985, fig. 36A), positioned entirely on right side of bursa copulatrix. Bursa copulatrix ovate, small relative to brood pouch, positioned well anterior to posterior edge of brood pouch, duct exiting anterior edge. Seminal receptacle ovate or globular, smaller than bursa copulatrix, positioned along anteroventral edge of bursa copulatrix, duct short or medium length. Sperm duct straight, opening to sperm tube in posterior 33% of pallial cavity. Oviduct issuing small gonopericardial duct proximal to coiled section. Renal oviduct a single, small, almost vertical loop; epithelium unpigmented. Distal to loop, oviduct connecting with seminal receptacle duct by a very short duct (Hershler, 1985, fig. 36D) and opening to posterior edge of albumen gland. Sperm tube rather broad, extending near to or abutting brood-pouch opening (Hershler, 1985, fig. 36F,G).

DISTRIBUTION.—The transfer of Tryonia kosteri to Durangonella extends the range of the latter genus from the Mexican plateau (Hershler and Thompson, 1992, map 5) into the Rio Grande drainage of New Mexico.

REMARKS.—Morrison (1945) erected Durangonella for four Mexican species that he distinguished from Tryonia by their weaker shell sculpture and different pattern of penial ornament. Taylor (1966b) added a fifth species (D. coahuilae), also from Mexico, which was later studied in detail by Hershler (1985) and Hershler and Thompson (1992). Durangonella coahuilae and D. kosteri are closely similar anatomically and well differentiated from Tryonia not only by the absence of penial papillae (e.g., the penial lobe of these species is nonglandular), but also by the smaller coil of the renal oviduct, absence of pigment on this coil, and the elongate sperm duct. More generally, Durangonella is distinguished from other cochliopines by the single, nonglandular, medial or distal lobe on the inner curvature of the penis. Because other congeners have not been collected alive (two were described from subfossils), the scope and content of Durangonella will require further study as this genus is closely similar in shell to Tryonia, which also ranges into northern Mexico.

Durangonella kosteri (Taylor, 1987), new combination

Tryonia (Paupertryonia) kosteri Taylor, 1987:45–47, fig. 23, tables 50, 51 [type locality, Sago Spring, 900 feet [280 m] west, 2,400 feet [740 m] south, sec. 5, T 10S, R 25E, Chaves County, New Mexico].

DIAGNOSIS.—Shell medium-sized, conical. Penial lobe positioned distally along inner edge.

DESCRIPTION.—Shell (Figures 11A, 28A) 2.5–5.0 mm tall. Males smaller than females (Taylor, 1987, table 50). Whorls, 4.25–5.75, slight to medium convexity, teleoconch sometimes sculptured with weak spiral lines. Protoconch (Figure 11B) about 0.75 whorl. Aperture ovate-pyriform, lip thin, adnate; umbilicus perforate. Operculum shown in Figure 11C,D; border of attachment region thickened. Ctenidial filaments about 27, pleated. Stomach with small posterior caecum. Radula with about 48 rows of teeth, length/width of ribbon 430%. Dorsal edge of central radular teeth (Figure 12A) weakly indented, basal tongue broadly V-shaped, central cusp broadly pointed, lateral cusps 3–6; basal cusps 1, small. Lateral teeth (Figure 12B) having 4 or 5 cusps on inner side and 5 or 6 cusps on outer side; outer wing very narrow, moderately flexed, length 180% width of tooth face. Inner marginal teeth with 24–30 cusps (Figure 12C), outer marginal teeth with 30–34 cusps (Figure 12D).

Pallial section of prostate gland 50% of total length. Pallial vas deferens exiting from ventral edge of prostate gland just behind anterior edge. Penial lobe club-like (Figure 29A). Ovary weakly branched. Oviduct loop sometimes containing sperm. Brood-pouch opening terminal, forming a well-developed, muscular sphincter (Figure 13A); brooded embryos 12–20. Seminal receptacle smaller than bursa copulatrix, duct short (Figure 13A,B). Sperm tube abutting brood-pouch opening.

DISTRIBUTION.—Vicinity of Roswell, Pecos River drainage, New Mexico.

REMARKS.—Durangonella kosteri is distinguished from its congeners by its broader shell. This snail further differs from D. coahuilae in the more distal position of the penial lobe. Taylor's (1987:45, fig. 23C) observation that this species has a penial papilla apparently was in error as the numerous males that were examined for this study all had a simple, nonglandular lobe.

MATERIAL EXAMINED.—UNITED STATES. New Mexico: Sago Spring, Chaves County, LACM 2252 (holotype), USNM 854091 (paratypes), USNM 854957; Lost River, Chaves County, USNM 854727; spring, Roswell Country Club, Chaves County, USNM 883771.

Pseudotryonia Hershler, new genus

TYPE SPECIES.—Tryonia alamosae Taylor, 1987.

DIAGNOSIS.—Shell trochoid to conic, smooth. Penis ornamented with 1–3 glandular papillae borne singly along edges; distal penis evenly rounded. Females ovoviviparous. Bursa copulatrix present (except in one species), seminal receptacle present; renal oviduct a small, unpigmented coil; sperm duct straight, opening to sperm tube in pallial cavity; sperm tube elongate.

DESCRIPTION.—Shell (Figure 15A–D) gray or clear, 1.2–5.0 mm tall, trochoid to conic, whorls 3.0–6.5. Periostracum thin. Protoconch (Figure 15E–H) small (<1.0 whorl), blunt, typically smooth; teleoconch smooth, whorls usually well rounded, widest above midpoint. Aperture usually small, inner lip complete across parietal wall, umbilicus variable. Operculum (Figure 16) thin, ovate, multispiral, nucleus eccentric, inner side usually smooth. Ctenidium well developed, connected to pericardium by short efferent vein; lateral surfaces of ctenidial filaments pleated. Osphradium usually small, narrow, centrally positioned along ctenidial axis. Kidney having small pallial portion, opening slightly muscularized. Pericardium bulging slightly into pallial cavity. Style sac about as long as remainder of stomach, posterior caecum of stomach small or absent. Rectum straight, anus near mantle edge. Radula with about 40–50 tooth rows, cusps generally narrowly pointed. Central teeth trapezoidal, with 1–3 pairs of basal cusps (Figure 17). Lateral teeth with enlarged central cusp, well-developed basal tongue; outer wing longer than width of tooth face (Figure 18A,D,E). Inner (Figure 18B,C) and outer (Figure 18F,G) marginal teeth with numerous (17–30) cusps borne largely or entirely on outer side; teeth with well-developed wings on outer edge and narrow, raised area extending from face to base. Large testis of numerous stalked lobes; seminal vesicle exiting from and tightly coiled against left side of anterior portion of testis. Prostate gland usually small, partly pallial. Visceral vas deferens opening to posteroventral edge of prostate gland, pallial vas deferens exiting from near anterior edge of prostate gland. Penis medium-sized, narrow, base expanded, terminal portion ciliated, blunt, without swelling along inner edge. Penial-duct opening through well-developed stylet. Edges of penis ornamented with 1–3 glandular papillae. Penis usually darkly pigmented with melanin distally, variably pigmented elsewhere. Females ovoviviparous, brooded young few, of different sizes (having up to 2.5 shell whorls). Ovary a small, simple sac. Glandular oviduct large, mostly consisting of thin-walled brood pouch, with a single posterior fold, anterior opening muscular (Figure 14A,C,D). Albumen gland very small, usually positioned entirely on right side of bursa copulatrix. Bursa copulatrix small (absent in one species) relative to brood pouch, positioned near pallial wall, with duct exiting anterior edge. Seminal receptacle usually smaller than bursa copulatrix, positioned along anteroventral portion of bursa copulatrix; duct short. Sperm duct elongate, opening to sperm tube in posterior 33% of pallial cavity. Proximal to coiled section oviduct issuing small gonopericardial duct. Renal oviduct a single, small, posterior-oblique loop; epithelia unpigmented. Distal to loop, oviduct connecting with seminal receptacle duct by a very short duct and opening to posterior edge of albumen gland. Sperm tube variable in width, opening in anterior half of pallial cavity, sometimes abutting or fused with opening of brood pouch.

ETYMOLOGY.—Referring to the similarity between these snails and members of the genus Tryonia. Gender feminine.

DISTRIBUTION.—Broadly disjunct in the southern United States, with species living in the Rio Grande basin and coastal drainages of Alabama and Florida (Map 2).

REMARKS.—Live animals of one species (P. brevissima) were examined for details of head-foot morphology, which are as follows: snout rectangular, distal lobes well developed; cephalic tentacles about 150% length of snout, slender, tapering distally; snout and tentacles variably pigmented with melanin and scattered yellow granules, granules concentrated around eyspots.

No synapomorphies defining this genus have been identified, and the group is distinguished from other cochliopines instead by a combination of an elongate female sperm duct and penial ornament consisting of one to three glandular papillae borne along the edges of this organ. Pseudotryonia is further distinguished from Tryonia by the absence of pigment on the renal oviduct, consistent opening of the sperm tube in the anterior portion of the pallial cavity, and the evenly rounded condition of the terminus of the penis in all species. Note that mtDNA evidence revealed Pseudotryonia as a well-supported clade (Hershler, Liu, and Mulvey, 1999).

Pseudotryonia adamantina (Taylor, 1987), new combination

Tryonia (Paupertryonia) adamantina Taylor, 1987:41–42, fig. 20, table 45 [type locality, Diamond Y Spring. Pecos County. Texas]

DIAGNOSIS.—Shell small- to medium-sized, conical. Penial ornament of 1 distal papilla on inner edge and 1 medial papilla on outer edge.

DESCRIPTION.—Shell (Figures 15A, 28B) 1.8–3.8 mm tall. Shell apex shown in Figure 15E. Whorls, 4.75–5.75, medium to highly convex, with well-developed shoulders, body whorl sometimes sculptured with weak spiral lines. Aperture ovate, lip complete, usually adnate, columellar lip usually straight, sometimes thickened; umbilicus usually perforate. Operculum shown in Figure 16A,E; whorl edges weakly frilled on outer side, inner side smooth. Ctenidial filaments about 22, black. Stomach with small posterior caecum. Radula with about 47 rows of teeth, length/width of ribbon 525%. Dorsal edge of central radular teeth (Figure 17A) weakly indented, basal tongue broadly V-shaped, central cusps much longer than laterals, narrowly pointed, lateral cusps 5–7, basal cusps 1 or 2. Lateral teeth having 4 or 5 cusps on inner side and 4–6 cusps on outer side; outer wing strongly flexed, length 170% width of tooth face. Inner marginal teeth with 19–24 cusps, outer marginal teeth (Figure 18F) with 23–30 cusps.

Prostate gland very small, bean-shaped, pallial section 50% of total length. Distal penis weakly pigmented, stylet large, penial duct nearly straight (Figure 29B). Oviduct loop posterior-oblique. Brood-pouch opening terminal, slightly muscularized; brooded embryos 7–10. Albumen gland sometimes exposed posterior to bursa copulatrix. Bursa copulatrix very small, ovate, lightly pigmented; seminal receptacle slightly smaller than bursa copulatrix, globular, lightly pigmented. Sperm-tube opening in anterior 50%-66% of pallial cavity.

DISTRIBUTION.—Endemic to type locality area, Pecos River basin, Texas.

REMARKS.—This species is distinguished from other congeners by its penial ornament, consisting of single papillae on the distal inner edge and medial outer edge (Figure 29B). Pseudotryonia adamantina also is unique within the genus in having pigmented sperm pouches.

MAP 2.—Type locality areas of Pseudotryonia species and junior synonyms thereof: I, Pecos River drainage, Texas (P. adamantina); 2, Rio Grande drainage, New Mexico (P. alamosae); 3, coastal drainage, Florida (P. brevissima); 4. Lake Panasoffkee, Florida (Amnicola harperi = P. brevissima); 5, Tombigbee River drainage, Alabama (Pseudotryonia sp.).

MATERIAL EXAMINED.—UNITED STATES. Texas: Diamond Y Spring, Pecos County, LACM 2089 (holotype), USNM 854075 (paratypes), USNM 873125, USNM 874915, USNM 892120.

Pseudotryonia alamosae (Taylor, 1987), new combination

Tryonia (Paupertryonia) alamosae Taylor, 1987:42–44, fig. 21, tables 46, 47 [type locality, Ojo Caliente, 700 feet [220 m] west, 1,700 feet [530 m] south, sec. 31, T8S, R 7W, unsurveyed, Socorro County, New Mexico].

DIAGNOSIS.—Shell medium-sized, ovate-conic to conic. Penial ornament of a single, distal, broadly conical papilla on inner edge.

DESCRIPTION.—Shell (Figures 15B, 28C) 2.1–4.6 mm tall. Males smaller than females (Taylor, 1987, table 46). Shell apex shown in Figure 15F. Whorls, 3.25–5.25, medium convexity, shouldered, teleoconch sometimes sculptured with weak spiral lines. Aperture ovate, lip complete, thin, usually adnate; umbilicus rimate to perforate. Operculum whorls weakly frilled on outer side (Figure 16C), border of attachment region slightly thickened all around (Figure 16G). Ctenidial filaments about 22. Posterior caecum of stomach small or absent. Radula with about 50 rows of teeth, length/width of ribbon 580%. Dorsal edge of central radular teeth (Figure 17B) well indented, basal tongue U-shaped, central cusps narrowly pointed, lateral cusps 4–6, basal cusps 1. Lateral teeth (Figure 18E) having 3 cusps on inner side and 4–6 cusps on outer side; outer wing well flexed, length 167% width of tooth face. Inner marginal teeth (Figure 18C) with 17–19 cusps, outer marginal teeth with 18–24 cusps.

Prostate gland small, bean-shaped, pallial section 33% of total length. Distal penis weakly tapering, weakly pigmented, stylet small, penial duct nearly straight (Figure 29C). Oviduct loop almost vertical. Brood-pouch opening terminal, slightly muscularized (Figure 14A); brooded embryos 6 or 7. Albumen gland on right side of bursa copulatrix. Bursa copulatrix minute, ovate; seminal receptacle ovate, about as large as and broadly overlapping bursa copulatrix (Figure 14B). Sperm tube fused anteriorly with brood-pouch opening (Figure 14A).

DISTRIBUTION.—Endemic to type locality area, Rio Grande basin, New Mexico.

REMARKS.—This snail is distinguished from other congeners by its penial ornament, consisting of a single papilla along the inner edge.

MATERIAL EXAMINED.—UNITED STATES. New Mexico: Ojo Caliente, Socorro County, LACM 2188 (holotype), USNM 854072 (paratypes), USNM 873231, USNM 883959.

Pseudotryonia brevissima (Pilsbry, 1890), new combination

Bythinella brevissima Pilsbry, 1890b:64 [type locality, Haulover Canal, at the head of the Indian River, Florida].

Amnicola harperi Dall, 1910:2 [type locality, swamp at south end of Lake Panasoffkee, six feet [2 m] below the present surface, Sumter County, Florida],—Thompson, 1968:52, 54 [lectotype selection, synonymized with Hyalopyrgus brevissimus].

Paludestrina brevissima Walker, 1918:137 [reassignment].

Hydrobia brevissima.—Baker, 1964:171 [reassignment].

Hyalopyrgus brevissimus.—Thompson, 1968:54, 56, figs. 6, 29G, 32C, 39G,H, 49F–I, 58C [disputed type locality; reassignment].

Tryonia brevissima.—Hershler and Thompson, 1992:110 [reassignment].

DIAGNOSIS.—Shell small- to medium-sized, trochiform to ovate-conic. Penial ornament of a small distal papilla along inner edge and a massive, almost basal papilla on outer edge.

DESCRIPTION.—Shell (Figures 15C, 28D,E) 1.3–4.4 mm tall. Shell apex shown in Figure 15G. Males much smaller than females (Thompson, 1968:52–53). Whorls, 3.0–5.0, medium to highly convex, widest above midpoint, sutures impressed, teleoconch sometimes sculptured with faint spiral striae. Aperture narrowly ovate, lip complete, very thin, usually adnate; umbilicus perforate or broadly open. Operculum shown in Figure 16B,F; inner side smooth. Ctenidial filaments about 28, ctenidium abutting pericardium. Stomach with very small posterior caecum. Radula with about 39 rows of teeth, length/width of ribbon 530%. Dorsal edge of central radular teeth (Figure 17C) moderately indented, basal tongue broadly convex, cusps small, central cusps broadly pointed, lateral cusps 5–7, basal cusps 1–3. Lateral teeth (Figure 18A) having 4 cusps on inner side and 4–6 cusps on outer side; outer wing weakly flexed, length 215% width of tooth face. Inner marginal teeth with 18–21 cusps, outer marginal teeth with 16–20 cusps.

Prostate gland small, subglobular, mostly visceral. Distal penis blunt, pigmented, stylet small, penial duct undulating (Figure 29D). Oviduct loop almost vertical. Brood-pouch opening subterminal, slightly muscularized (Figure 14D); brooded embryos 10. Albumen gland on right side of sperm pouch. Posterior bursa copulatrix absent, small bud-like sac on sperm tube in posterior pallial cavity possibly representing anterior vestige. Seminal receptacle globular, with narrow duct continuous with sperm tube (Figure 14E). Sperm tube very narrow, opening adjacent to brood-pouch opening.

DISTRIBUTION.—Central region of Florida Panhandle (Atlantic and Gulf Coastal drainages).

REMARKS.—Pseudotryonia brevissima is distinguished from other congeners by its squat shell and unique penial ornament, consisting of a distal papilla on the inner edge and a massive, almost basal papilla on the outer edge. This snail also is unique in the genus in only having a single female sperm pouch.

Thin sections of this species indicate that the female sperm pouch has a thin, muscular wall lacking an inner glandular component, which together with its short duct and typical connection with the oviduct suggests that this structure is homologous with the seminal receptacle and not the bursa copulatrix. Oriented sperm were not seen in the several specimens sectioned, although loose sperm were present in this pouch (and in the renal oviduct). The possibility that the minute anterior sac (opening to the sperm tube) is a remnant of the bursa copulatrix could not be confirmed in section.

MATERIAL EXAMINED.—UNITED STATES. Florida: Haulover Canal, at the head of the Indian River, Orange County, ANSP 62418 (holotype, Bythinella brevissima); Lake Panasoffkee, Sumter County, USNM 211011 (lectotype, Amnicola harperi), USNM 892069.

Pseudotryonia sp.

DIAGNOSIS.—Shell medium-sized, conical. Penial ornament of 2 distal, basally fused papillae on inner edge and 1 medial papilla on outer edge.

DESCRIPTION.—Shell (Figures 15D, 28F) 3.5–5.0 mm tall. Males smaller than females (Thompson, in press, tables 1, 2). Shell apex shown in Figure 15H. Whorls, 5.5–6.5, strongly convex, shouldered, widest above midpoint. Aperture subovate, lip complete, thin, adnate; umbilicus rimate. Operculum shown in Figure 16D,H; inner side smooth. Ctenidial filaments about 28. Stomach with medium-sized posterior caecum. Radula with about 51 rows of teeth, length/width of ribbon 580%. Dorsal edge of central radular teeth (Figure 17D) medium indented, basal tongue broadly convex or V-shaped, central cusps narrowly pointed, lateral cusps 4–6, basal cusps 1. Lateral teeth (Figure 18D) having 3 cusps on inner side and 4–6 cusps on outer side; outer wing medium flexed, length 170% width of tooth face. Inner marginal teeth (Figure 18B) with 17–19 cusps, outer marginal teeth (Figure 18G) with 18–24 cusps.

Prostate gland small, bean-shaped, pallial section 50% of total length. Distal penis rounded, pigmented, stylet small, penial duct undulating (Figure 29F). Oviduct loop posterior-oblique. Brood-pouch opening terminal, muscular (Figure 14C); brooded embryos 7. Albumen gland on right side of bursa copulatrix. Bursa copulatrix small, ovate; seminal receptacle much smaller than bursa copulatrix, ovate or globular (Figure 14F). Sperm duct with small proximal kink. Sperm-tube opening adjacent to brood-pouch opening.

DISTRIBUTION.—Endemic to a single spring in the Tombigbee River basin, Alabama.

REMARKS.—This novelty, which is being described by Thompson (in press), is distinguished from other congeners by the presence of two glandular papillae on the inner edge of the penis. The basally fused condition of these glands is unique among Tryonia-like snails.

MATERIAL EXAMINED.—UNITED STATES. Alabama: Salt Spring, Clarke County, UF 271517, USNM 860751, USNM 860752, USNM 860755.

Ipnobius Hershler, new genus

TYPE SPECIES.—Tryonia robusta Hershler, 1989.

DIAGNOSIS.—Shell ovate-conic to conic, smooth. Penis ornamented with single glandular papilla along outer edge; distal penis evenly rounded. Females ovoviviparous. Bursa copulatrix absent, seminal receptacle present, opening to renal oviduct by an elongate duct; renal oviduct a large, pigmented coil; sperm tube short.

DESCRIPTION.—Shell (Figures 20A, 28G) gray or clear, 1.1–2.2 mm tall, ovate-conic to conic, whorls 3.75–4.75, medium to high convexity. Periostracum thin. Protoconch (Figure 20B) small (<1.0 whorl), blunt, smooth or slightly roughened. Teleoconch smooth, whorls sometimes separated. Aperture small, inner lip complete across parietal wall, umbilicus broadly open. Operculum (Figure 20C,D) thin, ovate or subcircular, multispiral, nucleus eccentric or subcentral, inner side usually with well-developed muscle scar. Snout rectangular, slightly expanded distally; cephalic tentacles narrow, elongate (about 200% length of snout), weakly tapered distally, snout (apart from clear distal lips) and tentacles darkly pigmented with blue-black melanin, eyebrow of yellow granules well developed (from live animals). Ctenidium well developed, abutting pericardium posteriorly; lateral surfaces of ctenidial filaments pleated. Osphradium small, narrow, almost centrally positioned along the ctenidial axis. Kidney having small pallial portion, opening slightly muscularized. Pericardium bulging slightly into pallial cavity. Style sac about as long as remainder of stomach, posterior caecum of stomach absent. Rectum straight, anus near mantle edge. Radula with moderate number of tooth rows, cusps generally narrowly pointed. Central teeth (Figure 21A) trapezoidal, with 1 or 2 pairs of basal cusps. Lateral teeth (Figure 21B) with enlarged central cusp, well-developed basal tongue; outer wing longer than width of tooth face. Inner (Figure 21C) and outer (Figure 21D) marginal teeth with numerous (19–28) cusps borne largely or entirely on outer side; teeth with well-developed wing on outer edge and narrow, raised area extending from face to base. Large testis weakly lobate; seminal vesicle very small, exiting from and tightly coiled against left side of anterior portion of testis. Prostate gland small, ovate. Visceral vas deferens opening to postero-ventral edge of prostate gland, pallial vas deferens exiting from antero- dorsal edge of prostate gland. Penis medium-sized, narrow, base expanded; terminal portion ciliated, slightly tapering, rounded and slightly expanded distally, without swelling along inner edge (Hershler, 1989, fig. 58). Penial-duct opening through small stylet. Penis ornamented with single medial, broadly conical papilla along outer edge. Penis pigmented distally with melanin. Females ovoviviparous, brooded young few, of different sizes (having up to 2.0 whorls). Ovary a small, simple sac. Glandular oviduct large, mostly consisting of thin- walled brood pouch, with a posterior fold followed by a broad, circular loop, anterior opening muscular (Figure 19A). Small albumen gland extending posterior to seminal receptacle. Bursa copulatrix absent; seminal receptacle minute, issuing an elongate duct opening to renal oviduct. Proximal to coiled section, oviduct issuing a small gonopericardial duct. Renal oviduct a single, large, posterior-oblique loop; epithelium pigmented. Sperm tube narrow, opening in posterior 33% of pallial cavity.

ETYMOLOGY.—From Classical Greek, ipnos, “oven,” “furnace;” and bios, “life.” Referring to endemism of this genus in Death Valley, one of the hottest regions on earth. Gender masculine.

REMARKS.—This monotypic genus is differentiated by the uniquely elongate duct connecting the seminal receptacle and the renal oviduct (Figure 19B), which appears to have lengthened (relative to the typical condition in Tryonia-like snails) by splitting in a posterior direction. The penial ornament of this species, a single papilla on the outer edge (Figure 29F), also is unique among cochliopine snails.

The single sperm pouch of this species is considered a seminal receptacle as thin sections reveal thin, muscular walls, absence of a thick inner glandular layer, and presence of oriented sperm (also seen in portions of the renal oviduct).

Ipnobius robustus (Hershler, 1989), new combination

Tryonia robusta Hershler, 1989:208–211, figs. 51d, 52, 55–58. table 2 [type locality, Nevares Springs, spring on travertine mound. Inyo County. California].

DESCRIPTION.—Shell (Figures 20A, 28G) 1.1–2.2 mm tall. Shell apex shown in Figure 20B. Whorls, 3.75–4.75, shouldered. Aperture ovate-pyriform, lip medium thickness, adnate or disjunct. Operculum shown in Figure 20C,D; whorl edges slightly frilled, inner side smooth. Ctenidial filaments about 17, without pleats. Radula with about 54 rows of teeth; length/width of ribbon 580%. Dorsal edge of central radular teeth well indented (Figure 21A); basal tongue broadly V- or U-shaped, central cusp broadly triangular, lateral cusps 5–7, basal cusps 1 or 2 or 2 (Figure 21A). Lateral teeth (Figure 21B) with 2–4 cusps on inner side and 4 or 5 cusps on outer side; outer wing weakly flexed, length 160% width of tooth face. Inner marginal teeth (Figure 21C) with 19–24 cusps, outer marginal teeth (Figure 21D) with 21–28 cusps.

Penial duct nearly straight (Figure 29F). Brooded embryos 3. Albumen gland comprising a semicircular loop posterodorsal to seminal receptacle. Seminal receptacle pigmented, ovate (Figure 19B).

DISTRIBUTION.—Endemic to type locality and nearby Travertine Springs, lower Amargosa River basin, California.

REMARKS.—Samples collected in the early 1970s (illustrated herein) differ from more recent (1985) collections of this species (Hershler, 1989, figs. 55, 56d) in that shells are smaller, more loosely coiled, and have a more circular aperture (the operculum also is subcircular rather than ovate). This temporal variation may be attributable to intervening modifications of the type locality associated with spring development.

MATERIAL EXAMINED.—UNITED STATES. California: Nevares Springs, Inyo County, USNM 860411 (holotype), USNM 883311, USNM 883313.

Figures

FIGURE 1.—Distal penis (dorsal side) of Tryonia clathrata: A, whole mount, USNM 873192 (bar=96 μm); B, scanning electron micrograph, USNM 850291 (bar=86 μm). (Ds=distal swelling, Pa=glandular papilla, St= stylet).

FIGURE 2.—Anatomical details of Tryonia clathrata. USNM 850291 (bars=250 μm): A, prostate gland (right side), showing insertion of vas deferens; B, contents of posterior section of pallial cavity, viewed from right side; C, stomach (dorsal side); D, anterior section of testis and abutting seminal vesicle. (Ast=anterior stomach chamber, Cae=posterior caecum, Ct=ctenidium, In=intestine, Ki=kidney, Odg=opening of digestive gland into stomach, Oe=oesophagus, Pc=pericardium, Pr=prostate gland, Pst=posterior stomach chamber, Re=rectum, Ss= style sac, Sv=seminal vesicle, Ts=testis, Vdl =visceral vas deferens, Vd2=pallial vas deferens.)

FIGURE 3.—Distal female genitalia (viewed from left side) of Tryonia species (bars=200 μm) (gonopericardial- duct not shown): A, Tryonia ericae, USNM 850312; B, Tryonia aequicostata, USNM 874831; C,D, Tryonia imitator, USNM 892057. (Ag=albumen gland. Bp=brood pouch, Bu=bursa copulatrix, Dag=connection between oviduct and albumen gland, Ro=renal oviduct, Sd=sperm duct, Sr=seminal receptacle, St=sperm tube.)

FIGURE 4.—Shell diversity among Tryonia species: A, Tryonia salina, USNM 857998 (shell height, 2.7 mm); B, Tryonia quitobaquitae, USNM 847256 (2.1 mm); C, Tryonia gilae, USNM 883956 (2.6 mm); D, Tryonia hertleini. USNM 600498 (2.8 mm); E, Tryonia clathrata, USNM 791488 (5.5 mm); F, Tryonia angulata, USNM 883304 (3.0 mm); G, Tryonia aequicostata, USNM 892070 (5.2 mm); H, Tryonia circumstriata, USNM 883958 (3.4 mm); I, Tryonia elata, USNM 850309 (2.2 mm); J, Tryonia exigua, USNM 874034 (6.0 mm); K, Tryonia porrecta, USNM 854744 (5.4 mm); L, Tryonia margae, USNM 854599 (3.4 mm).

FIGURE 5.—Scanning electron micrographs of shell apices of Tryonia species: A, Tryonia circumstriata (embryo from brood pouch), USNM 883958 (bar= 150 μm); B, Tryonia imitator (embryo from brood pouch), USNM 892057 (bar=150 μm); C, Tryonia circumstriata, USNM 883958 (bar=92 μm); D, Tryonia quitobaquitae. USNM 847256 (bar=75 μm); E, Tryonia gilae. showing well-demarcated protoconch, USNM 883956 (bar=75 μm); F, Tryonia ericae, close up of protoconch, USNM 850312 (bar=45 μm)

FIGURE 6.—Scanning electron micrographs of opercula (A–C, outer side; D–F, inner side) of Tryonia species: A, Tryonia salina, USNM 857998 (bar=300 μm); B, Tryonia cheatumi, USNM 883957 (bar=333 μm); C,F, Tryonia clathrata, USNM 850291 (bars=300 μm); D, Tryonia circumstriata, USNM 883406 (bar=240 μm); E, Tryonia variegata, USNM 850314 (bar=214 μm).

FIGURE 7.—Scanning electron micrographs of central radular teeth of Tryonia species: A, Tryonia rowlandsi, USNM 857953 (bar=12 μm); B, Tryonia salina, USNM 857998 (bar=15 μm); C, Tryonia porrecta, USNM 873441 (bar= 15 μm); D, Tryonia clathrata,USNM 850291 (bar= 12 μm); E, Tryonia angulata, USNM 883304 (bar= 11 μm); F, Tryonia circumstriata, USNM 883406 (bar= 12 μm).

FIGURE 8.—Scanning electron micrographs of lateral radular teeth of Tryonia species: A, Tryonia clathrata, USNM 850291 (bar=12 μm); B, Tryonia cheatumi, USNM 883957 (bar= 17 μm); C, Tryonia imitator, USNM 892057 (bar=15 μm): D, Trvonia elata USNM 850309 (bar= 10 um)

FIGURE 9.—Scanning electron micrographs of inner marginal radular teeth of Tryonia species: A, Tryonia angulata, USNM 883304 (bar= 12 μm); B, Tryonia porrecta, USNM 873441 (bar=17 μm); C, Tryonia elata. USNM 850309 (bar=8 μm); D, Tryonia circumstriata. USNM 883406 (bar= 13 μm)

FIGURE 10.—Scanning electron micrographs of outer marginal radular teeth of Tryonia spccies: A, Tryonia gilae. USNM 883956 (bar=9 μm); B, Tryonia rowlandsi. USNM 857953 (bar=10 μm): C, Tryonia margae. USNM 883308 (bar=10μm); D, Tryonia variegata. USNM 850314 (bar= 13 μm).

FIGURE 11.—Morphology of Durangonella kosteri: A, scanning electron micrograph of shell, USNM 854727 (shell height, 3.2 mm); B, scanning electron micrograph of shell apex, USNM 854727 (bar=133 μm); C,D, scanning electron micrographs of opercula (outer and inner sides, respectively), USNM 883771 (bar=90 μm); E, whole mount of distal section of penis showing non-glandular lobe, USNM 854957 (bar=96 μm). (Pl=penial lobe.)

FIGURE 12.—Scanning electron micrographs of radula of Durangonella kosteri, USNM 883771: A, central teeth (bar=12 μm); B, lateral teeth (bar=15 μm); C, inner marginal tooth (bar=13 μm); D, outer marginal teeth (bar= 17 μm).

FIGURE 13.—Distal female genitalia (viewed from left side) of Durangonella kosteri. USNM 854957 (bar=500 μm) (gonopericardial duct not shown): A, brood pouch and associated structures; B, bursa copulatrix and associated structures, with brood pouch removed. (Bp=brood pouch, Bu=bursa copulatrix, Dag=connection between oviduct and albumen gland, Ro=renal oviduct, Sd=sperm duct, Sr=seminal receptacle, St=sperm tube.)

FIGURE 14.—Distal female genitalia (viewed from left side) of Pseudotryonia species (bars=250 μm) (gonopericardial duct not shown): A,B, Pseudotryonia alamosae, USNM 883959; C,F, Pseudotryonia sp., USNM 860751; D,E, Pseudotryonia brevissima, USNM 892069. (Note the minute sac opening to sperm tube in pallial cavity. Bp=brood pouch, Bu=bursa copulatrix, Dag=connection between oviduct and albumen gland, Ro=renal oviduct, Sd=sperm duct, Sr=seminal receptacle, St=sperm tube.)

FIGURE 15.—Scanning electron micrographs of entire shells (A–D) and shell apices (E–H) of Pseudotryonia species: A, Pseudotryonia adamantina, USNM 874915 (shell height, 2.3 mm); B, Pseudotryonia alamosae, USNM 883959 (2.1 mm); C, Pseudotryonia brevissima, USNM 892069 (3.4 mm); D. Pseudotryonia sp., USNM 860755 (3.5 mm); E, Pseudotryonia adamantina, USNM 874915 (bar=100 μm); F, Pseudotryonia alamosae, USNM 883959 (bar=100 μm); G, Pseudotryonia brevissima. USNM 892069 (bar=75 μm); H, Pseudotryonia sp., USNM 860752 (bar=75 μm).

FIGURE 16.—Scanning electron micrographs of opercula (A–D, outer side; D–H, inner side) of Pseudotryonia species: A,E, Pseudotryonia adamantina. USNM 874915 (bars=222, 214 μm, respectively); B,F, Pseudotryonia brevissima, USNM 892069 (bars=360, 400 μm, respectively); C,G, Pseudotryonia alamosae, USNM 873231 (bars=222, 231 μm, respectively); D,H, Pseudotryonia sp., USNM 860752 (bars=360 μm).

FIGURE 17.—Scanning electron micrographs of central radular teeth of Pseudotryonia species: A, Pseudotryonia adamantina, USNM 874915 (bar=8.6 μm); B, Pseudotryonia alamosae, USNM 873231 (bar=8.6 μm); C, Pseudotryonia brevissima, USNM 892069 (bar=12 μm); D, Pseudotryonia sp., USNM 860752 (bar=15 μm).

FIGURE 18.—Scanning electron micrographs of lateral (A,D,E), inner marginal (B,C) and outer marginal (F,G) radular teeth of Pseudotryonia species: A, Pseudotryonia brevissima, USNM 892069 (bar=10 μm); B,D,G, Pseudotryonia sp., USNM 860752 (bars=15, 15, 20 μm, respectively); C,E, Pseudotryonia alamosae, USNM 873231 (bars=11 μm); F, Pseudotryonia adamantina, USNM 874915 (bar=15 μm).

FIGURE 19.—Distal female genitalia (viewed from left side) of Ipnobius robustus, USNM 883313 (bar=250 μm) (gonopericardial duct not shown): A, brood pouch and associated structures; B, seminal receptacle and associated structures. (Ag=albumen gland, Bp=brood pouch, Dag= connection between oviduct and albumen gland, Ro= renal oviduct, Sr=seminal receptacle, St= sperm tube.)

FIGURE 20.—Scanning electron micrographs of morphology of Ipnobius robustus, USNM 883313: A, shell (height, 2.2 mm); B, shell apex (bar=86 μm); C, outer side of operculum (bar=230 μm); D, inner side of operculum (bar=207 μm).

FIGURE 21.—Scanning electron micrographs of radula of Ipnobius robustus, USNM 883313: A, central teeth (bar = 12μm); B, lateral tooth (bar = 11μm); C, inner marginal tooth (bar= 12μm); D, outer marginal teeth (bar= 15μm).

FIGURE 22.—Type specimens of Tryonia species and junior synonyms thereof (shells not drawn to same scale): A, holotype,T. aequicostata, ANSP 27985 (shell height, 6.0 mm); B, holotype, Fontigens oxybeles (=T. aequicostata), ANSP 186751 (5.5 mm); C, holotype, T. angulata, USNM 859151 (3.6 mm); D, lectotype, T. cheatumi, ANSP 16388 (3.9 mm); E, holotype, T. circumstriata, USNM 440734 (5.3 mm); F,paratype, T. stocktonensis (=T. circumstriata), USNM 854092 (3.3 mm); G, lectotype, T. clathrata, ANSP 27969 (5.0 mm); H, holotype, T. elata, USNM 859159 (1.8 mm); I, holotype, T. ericae, USNM 859162 (1.7 mm).

FIGURE 23.—Type specimens of Tryonia species and junior synonyms thereof (shells not drawn to same scale): A, lectotype, T. exigua, BMNH 1893.2.4.1769 (shell height, 7.3 mm); B, paratypec, T. gilae Taylor, USNM 854074 (3.0 mm); C, holotype, T. gilae Hershler, 1988= T. gilae Taylor, 1988), USNM 859059 (3.4 mm); D. paratype, T. hertleini, CAS 64919 (2.6 mm); E, lectotype, T. imitator, ANSP 62670 (2.5 mm); F, holotype, Paludestrina curta (=T. imitator), USNM 162542 (3.5 mm); G, holotype, T. margae, USNM 860408 (3.5 mm); H, holotype, T. monitorae, USNM 892046 (3.0 mm).

FIGURE 24.—Types and other historical specimens of Tryonia species and junior synonyms thereof (shells not drawn to same scale): A, possible syntype, T. porrecta. BMNH 1995123 (shell height, 6.7 mm); B. lectotype, Amnicola protea (=T. porrecta). USNM 120174 (5.4 mm); C, lectotype. Melania exigua (=T. porrecta), ANSP 27965 (4.6 mm); D, holotype, Pyrgulopsis imminens (=T.porrecta), SBMNH 35497 (3.8 mm); E, holotype, Pyrgulopsis blakeana (= T. porrecta), SBMNH 35500 (4.2 mm); F, holotype. Pyrgulopsis cahuillarum (= T. porrecta), SBMNH 35503 (5.7 mm); G, holotype, T. quitobaquitae, USNM 859061 (2.0 mm); H, holotype, T. rowlandsi, USNM 860409 (2.2 mm); I, holotype, T. salina. USNM 860410 (3.3 mm); J. holotype, T. variegata. USNM 859166 (4.0 mm).

FIGURE 25.—Penes (dorsal side) of Tryonia species (bars=250µm): A, Tryonia aequicostata, USNM 874831; B, Tryonia angulata. USNM 850299; C, Tryonia cheatumi. USNM 883952; D, Tryonia circumstriata. USNM 892020; E, Tryonia clathrata. USNM 873192; F, Tryonia elata. USNM 850309. (Pigmented areas indicated by dense stipple; penial ducts indicated by stippled lines.)

FIGURE 26.—Penes (dorsal side) of Tryonia species (bars=250μm): A, Tryonia ericae, USNM 850312; B, Tryonia exigua, USNM 874034; C, Tryonia gilae, USNM 847253; D, Tryonia hertleini, UMMZ uncat.; E, Tryonia imitator. USNM 892057. (Pigmented areas indicated by dense stipple; penial ducts indicated by stippled lines.)

FIGURE 27.—Penes (dorsal side) of Tryonia species (bars = 250µm): A, Tryonia margae. USNM 857952; B, Tryonia monitorae. USNM 860760; C, Tryonia quitobaquitae. USNM 847256; D, Tryonia rowlandsi, USNM 857953; E, Tryonia salina. USNM 883326; F, Tryonia variegata. USNM 850314. (Pigmented areas indicated by dense stipple; penial ducts indicated by stippled lines.)

FIGURE 28.—Type and other representative specimens of species of Durangonella, Pseudotryonia, and Ipnobius, and junior synonyms thereof (shells not drawn to same scale): A, paratype, Durangonella kosteri, USNM 854091 (shell height, 4.0 mm); B, paratype, Pseudotryonia adamantina, USNM 854075 (3.3 mm); C, paratype, Pseudotryonia alamosae, USNM 854072 (3.2 mm); D, holotype, Bythinella brevissima (= P. brevissima), ANSP 62418 (3.0 mm); E, lectotype, Amnicola harperi (=P. brevissima), USNM 211011 (1.3 mm); F, Pseudotryonia sp., UF 271517 (4.2 mm); G, holotype, Ipnobius robustus USNM 860411 (1.9 mm).

FIGURE 29.—Penes (dorsal side) of species of Durangonella, Pseudotryonia, and Ipnobius (bars=200 μm): A, Durangonella kosteri, USNM 854957; B, Pseudotryonia adamantina, USNM 873125; C. Pseudotryonia alamosae, USNM 873231; D, Pseudotryonia brevissima, USNM 892069; E, Pseudotryonia species, USNM 860751; F, Ipnobius robustus, USNM 883313.

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First page of text should carry the title and author at the top of the page; second page should have only the author's name and professional mailing address, to be used as an unnumbered footnote on the first page of printed text.

Center heads of whatever level should be typed with initial caps of major words, with extra space above and below the head, but no other preparation (such as all caps or underline, except for the underline necessary for generic and specific epithets). Run-in paragraph heads should use period/dashes or colons as necessary.

Tabulations within text (lists of data, often in parallel columns) can be typed on the text page where they occur, but they should not contain rules or numbered table captions.

Formal tables (numbered, with captions, boxheads, stubs, rules) should be submitted as carefully typed, double-spaced copy separate from the text; they will be typeset unless otherwise requested. If camera-copy use is anticipated, do not draw rules on manuscript copy.

Taxonomic keys in natural history papers should use the aligned-couplet form for zoology and may use the multi-level indent form for botany. If cross referencing is required between key and text, do not include page references within the key, but number the keyed-out taxa, using the same numbers with their corresponding heads in the text.

Synonymy in zoology must use the short form (taxon, author, year: page), with full reference at the end of the paper under “Literature Cited.” For botany, the long form (taxon, author, abbreviated journal or book title, volume, page, year, with no reference in “Literature Cited”) is optional.

Text-reference system (author, year: page used within the text, with full citation in “Literature Cited” at the end of the text) must be used in place of bibliographic footnotes in all Contributions Series and is strongly recommended in the Studies Series: “(Jones, 1910:122)” or “…Jones (1910:122).” If bibliographic footnotes are required, use the short form (author, brief title, page) with the full citation in the bibliography.

Footnotes, when few in number, whether annotative or bibliographic, should be typed on separate sheets and inserted immediately after the text pages on which the references occur. Extensive notes must be gathered together and placed at the end of the text in a notes section.

Bibliography, depending upon use, is termed “Literature Cited,” “References,” or “Bibliography.” Spell out titles of books, articles, journals, and monographic series. For book and article titles use sentence-style capitalization according to the rules of the language employed (exception: capitalize all major words in English). For journal and series titles, capitalize the initial word and all subsequent words except articles, conjunctions, and prepositions. Transliterate languages that use a non-Roman alphabet according to the Library of Congress system. Underline (for italics) titles of journals and series and titles of books that are not part of a series. Use the parentheses/colon system for volume (number): pagination: “10(2):5–9.” For alignment and arrangement of elements, follow the format of recent publications in the series for which the manuscript is intended. Guidelines for preparing bibliography may be secured from Series Section, SI Press.

Legends for illustrations must be submitted at the end of the manuscript, with as many legends typed, double-spaced, to a page as convenient.

Illustrations must be submitted as original art (not copies) accompanying, but separate from, the manuscript. Guidelines for preparing art may be secured from Series Section, SI Press. All types of illustrations (photographs, line drawings, maps, etc.) may be intermixed throughout the printed text. They should be termed Figures and should be numbered consecutively as they will appear in the monograph. If several illustrations are treated as components of a single composite figure, they should be designated by lowercase italic letters on the illustration; also, in the legend and in text references the italic letters (underlined in copy) should be used: “Figure 9b.” Illustrations that are intended to follow the printed text may be termed Plates, and any components should be similarly lettered and referenced: “Plate 9b.” Keys to any symbols within an illustration should appear on the art rather than in the legend.

Some points of style: Do not use periods after such abbreviations as “mm, ft, USNM, NNE.” Spell out numbers “one” through “nine” in expository text, but use digits in all other cases if possible. Use of the metric system of measurement is preferable; where use of the English system is unavoidable, supply metric equivalents in parentheses. Use the decimal system for precise measurements and relationships, common fractions for approximations. Use day/month/year sequence for dates: “9 April 1976.” For months in tabular listings or data sections, use three-letter abbreviations with no periods: “Jan, Mar, Jun,” etc. Omit space between initials of a personal name: “J.B. Jones.”

Arrange and paginate sequentially every sheet of manuscript in the following order: (1) title page, (2) abstract, (3) contents, (4) foreword and/or preface, (5) text, (6) appendixes, (7) notes section, (8) glossary, (9) bibliography, (10) legends, (11) tables. Index copy may be submitted at page proof stage, but plans for an index should be indicated when manuscript is submitted.