THE NAUTILUS 101(1):25-32, 1987 Page 25 . North American Hydrobiidae (Gastropoda: Rissoacea): Redescription and Systematic Relationships of Tryonia Stimpson, 1865 and Pyrgulopsis Call and Pilsbry, 1886 Robert Hershler Fred G. Thompson Department of Invertebrate Zoology Florida State Museum National Museum of Natural History University of Florida Smithsonian Institution Gainesville, FL 32611, USA Washington, DC 20560, USA ABSTRACT scribed) in the Southwest. Taylor (1966) placed Tryonia in the Littoridininae Taylor, 1966 on the basis of its Anatomical details are provided for the type species of Tryonia turreted shell and glandular penial lobes. It is clear from Stimpson, 1865, Pyrgulopsis Call and Pilsbry, 1886, Fonteli- cella Gregg and Taylor, 1965, and Microamnicola Gregg and the initial descriptions and subsequent studies illustrat- Taylor, 1965, in an effort to resolve the systematic relationships ing the penis (Russell, 1971: fig. 4; Taylor, 1983:16-25) of these taxa, which represent most of the generic-level groups that Fontelicella and its subgenera, Natricola Gregg and of Hydrobiidae in southwestern North America. Based on these Taylor, 1965 and Microamnicola Gregg and Taylor, 1965 and other data presented either herein or in the literature, belong to the Nymphophilinae Taylor, 1966 (see Hyalopyrgus Thompson, 1968 is assigned to Tryonia; and Thompson, 1979). While the type species of Pyrgulop- Fontelicella, Microamnicola, Nat ricola Gregg and Taylor, 1965, sis, P. nevadensis (Stearns, 1883), has not received an- Marstonia F. C. Baker, 1926, and Mexistiobia Hershler, 1985 atomical study, the penes of several eastern species have are allocated to Pyrgulopsis. been examined by Thompson (1977), who suggested that The ranges of both Tryonia and Pyrgulopsis include parts the genus may be a nymphophiline. The scant published of eastern and western America and northern Mexico. Tryonia is closely related to a group of North and Central American morphological data do not, however, allow meaningful littoridinine genera having an elongate-conic shell and (mam- comparisons of the above with other Hydrobiidae. miform) glandular penial lobes, and Pyrgulopsis (Nympho- Our anatomical study of the type species of Tryonia philinae) is closely allied to Cincinnatia Pilsbry, 1891 from and Hyalopyrgus Thompson, 1968 showed that Hyalo- eastern North America. pyrgus, endemic to Florida (and placed in the Littori- dininae by Davis et al., 1982), should be allocated to Tryonia. Similarly, study of type species and published INTRODUCTION accounts indicated that Fontelicella, Nat ricola, Mi- croamnicola, as well as Mexistiobia Hershler, 1985 (from Prosobranch snails of the family Hydrobiidae comprise northern Mexico) and Marstonia F. C. Baker, 1926 a major faunal element of North American freshwaters, (widespread in eastern North America) should be allo- numbering some 28 genera and 148 species (Burch, cated to Pyrgulopsis. In this paper we redescribe Tryon- 1982). Despite their diversity and ubiquity, North ia and Pyrgulopsis and briefly discuss their affinities. American Hydrobiidae are poorly understood in terms of systematics, as the anatomy of few species is known. MATERIALS AND METHODS While recent advances have been made in the system- atic study of southeastern Hydrobiidae (Thompson, 1968, Anatomical illustrations given in this paper are based on 1969, 1977, 1984; Thompson & McCaleb, 1978), the fau- study of the following lots (representing fully relaxed na of other large expanses of territory is virtually un- alcohol material unless otherwise indicated): Tryonia studied. clathrata Stimpson, 1865, Moapa Springs, Clark County, One such fauna is that of the arid Southwest. Of the NV, USA, USNM 850291; Hyalopyrgus aequicostatus generic-group taxa found in this region, only Flumini- (Pilsbry, 1889), Lake Dora, Lake County, FL, USA, cola Stimpson, 1865 has received sufficient morpholog- USNM 847212; Alexander Springs, Lake County, FL, ical study to allow clarification of its relationships USA, UF uncatalogued lot; Pyrgulopsis nevadensis, re- (Thompson, 1984). Relatively little is known of Pyrgu- hydrated (in Bouin's solution) bodies, south end of Pyr- lopsis Call and Pilsbry, 1886, Tryonia Stimpson, 1865, amid Lake, Washoe County, NV, USA, UF uncata- and Fontelicella Gregg and Taylor, 1965, the latter two logued lot; Pyrgulopsis archimedis S. S. Berry, 1947, of which comprise more than 30 species (mostly unde- unrelaxed, Upper Klamath Lake, Klamath County, OR, Page 26 THE NAUTILUS, Vol. 101, No. 1 Figure 1. Photograph (SEM) of holotype of Tryonia clathrata Colorado Desert, CA, USA (but see Taylor, 1966: Stimpson, Figure 9. Photograph (SEM) of central radular teeth of Shell height is Figure 2. Close- 197), ANSP 27969. 4.36 mm. Tryonia aequicostata (Pilsbry), Lake Dora, Lake County, FL, Tryonia clathrata Stimpson, Moapa up photograph of shell of USA, USNM 847212. Scale bar equals 10 am. Figure 10. Springs, Clark County, NV, USA, USNM 850291, showing Photograph of protoconch of Tryonia aequicostata (Pilsbry) sculptural pattern. The height of the portion of shell photo- (from same lot as above). Scale bar equals 150 am. Figure Figure 3. Photograph of shell of Tryon- graphed is 2.36 mm. 11. Photograph of central radular teeth of Tryonia clathrata Lake Dora, Lake County, FL, USA, ia aequicostata (Pilsbry), Stimpson, Moapa Springs, Clark County, NV, USA, USNM printed to same enlargement as figure 1. Fig- USNM 847212, 850291. Scale bar equals 10 am. Figure 12. Photograph of ure 4. Photograph of paratype of Pyrgulopsis nevadensis, protoconch of Tryonia clathrata Stimpson (from same lot as County, NV, USA, USNM south end of Pyramid Lake, Washoe above). Scale bar equals 150 am. 75450, printed to same enlargement as figure 1. Figure 5. Photograph of shell of Pyrgulopsis lustrica (Pilsbry), Little Lakes, Herkimer County, NY, USA, USNM 28085, printed to 1985, small spring at Tierra Blanca, SW of Cuatro Cie- same enlargement as figure 1. Figure 6. Photograph of para- negas, Coahuila, MEX, ANSP A98881. type of Pyrgulopsis californiensis (Gregg and Taylor), Campo Snails were dissected in dilute Bouin's solution at 50 x Creek, San Diego County, CA, USA, USNM 850292, printed using a Wild M-8 dissecting microscope. Ciliation pat- to same enlargement as figure 1. Figure 7. Photograph of terns on the cephalic tentacles and penis were examined shell of Pyrgulopsis micrococcus (Pilsbry), Springdale Springs, using a Hitachi S-570 scanning electron microscope, with printed to same en- Nye County, NV, USA, USNM 850297, the animals having first been graded into 100% ETOH largement as figure 1. Figure 8. Photograph of shell of Pyr- gulopsis manantiali (Hershler), spring at Tierra Blanca, SW and dried using a Denton DCP-1 Critical Point Drier. of Cuatro Cienegas, Coahuila, MEX, ANSP A9888L, printed Shells and radulae were cleaned with Clorox and then to same enlargement as figure 1. photographed using the scanning electron microscope. USA, ANSP A602b; Pyrgulopsis letsoni (Walker, 1901), SYSTEMATICS creek W of Crenshaw Lake, Oakland County, MI, USA, Genus Tryonia Stimpson, 1865 UF 91726; Pyrgulopsis scalariformis (Wolf, 1869), Mer- amec River, 12.0 km SE of Leesburg, Crawford County, Tryonia Stimpson, 1865:54. Type species: Tryonia clathrata MO, USA, UF 91727. Fontelicella (sensu stricto) cali- Stimpson, 1865:54, by original designation; 1865:54. forniensis Gregg and Taylor, 1965, Campo Creek, San Hyalopyrgus Thompson, 1968:43. Type species: Bythinella Diego County, CA, USA, USNM 850292 (paratypes); aequicostata Pilsbry, 1889:86, by original designation; Thompson, 1968:45. Fontelicella (Microamnicola) micrococcus (Pilsbry in Stearns, 1893), Springdale Springs, Nye County, NV, Diagnosis: Shell (figures 1-3) colorless, transparent, USA, USNM 850297; Mexistiobia manantiali Hershler, elongate-conic to turreted, 1.7-7.0 mm tall with 4.0-8.0 R. Hershler and F. G. Thompson, 1987 Page 27 Figure 13. Photograph (SEM) of left tentacle of Tryonia clathrata Stimpson, Moapa Springs, Clark County, NV, USA, USNM 850291, showing ciliary tracts. Scale bar equals 176 p.m. Figure 14. Photograph of right tentacle of Tryonia clathrata Stimpson (from same lot as above). Scale bar equals 170 Aim. Figure 15. Close-up photograph of ciliary tracts on right tentacle of Tryonia clathrata Stimpson (same specimen as above). Scale bar equals 30 /2111. Figure 16. Photograph of left tentacle of Tryonia aequicostata (Pilsbry), Alexander Springs, Lake County, FL, USA, UF uncatalogued lot. Scale bar equals 176 Aim. Figure 17. Photograph of right tentacle of Tryonia aequicostata (Pilsbry) (from same lot as above). Scale bar equals 200 Atm. Figure 18. Photograph of penial tip of Tryonia clathrata, Moapa Springs, Clark County, NEV, USA, USNM 850291, showing sparse ciliation, terminal papilla, and blunt swelling on inner (left) side. Scale bar equals 50 Am. whorls; typically high-spired with rounded whorls and glandular lobes on the inner curvature. Distal portion of indented sutures. Aperture simple, unthickened, and penis ciliated (figure 18) to varying degrees, base some- complete. Umbilicus narrow or absent. Sexual dimor- times also ciliated. Tip of penis with blunt swelling on phism pronounced, with males often half of female shell inner curvature. Females ovoviviparous, with 3-15 em- height. Protoconch (figures 10, 12) flat or slightly pro- bryos brooded in enlarged capsule gland (figure 21). truding, smooth or slightly wrinkled. Teleoconch sculp- Capsule gland with muscular sphincter at anterior end.