Pyrgulopsis nevadensis (Stearns 1883)

Pyrgulopsis nevadensis (Stearns, 1883)

Pyrgula nevadensis Stearns, 1883:173 [unlabeled figure, p. 173; not Fluminicola nevadensis Walker, 1916].—Call, 1884:21.—Call and Beecher, 1884: 851, figs. 1–5.—Baker, 1964:174.

Pyrgulopsis nevadensis.—Call and Pilsbry, 1886:10, pl. II: figs. 1–10.—Ancey, 1888:189.—Pilsbry, 1891c:329; 1899:122.—Hannibal. 1912b:189.—Walker, 1918:30, figs. 101, 102.—Thiele, 1928:378.—Wenz, 1939:558, fig. 1499.—Gregg, 1945:69.—Berry, 1947:77, pl. 7: fig. 7.—Baily and Baily, 1951:52, pl. 4: fig. 9.—Jacobson, 1952a:15.—Taylor, 1960a:327; 1970:33; 1975:127–128.—Burch, 1982:28, figs. 256, 270–272.—Hershler and Thompson, 1987:28, figs. 4, 25–29.—Turgeon et al., 1988:62.

Pyrgalopsis [sic] nevadensis.—Brues, 1932:278.

Pyrgulopsis nevadensis var. ecarinata Ancey, 1888:189.

Pyrgulopsis nevadensis paiutica Baily and Baily, 1951:52, pl. 4: fig. 10, right figure.—Jacobson, 1952a:16; 1952b:70.—Burch, 1982:28.

Pyrgulopsis paiutica.—Baker, 1964:175.

DIAGNOSIS.—Shell ovate-conic to turriform, usually basally carinate, medium to large-sized, weakly umbilicate. Penial filament medium length, lobe short. Penial ornament a small terminal gland, and ventral gland.

DESCRIPTION.—Shell (Figure 22a,b) ovate-conic to turriform; height, 3.5–5.7 mm; whorls, 4.5–6.0. Protoconch appearing near smooth, but usually eroded. Apical whorls well rounded, late teleoconch whorls much less so, sometimes shouldered; sculpture of strong growth lines. Strong peripheral carina usually present from beginning of third whorl to aperture, but carina development varying to weak cord or very slight angulation. Aperture ovate, broadly adnate to body whorl. Inner lip complete, thin. Outer lip prosocline. Umbilicus absent to narrowly rimate. Periostracum light brown.

Operculum (Figure 22c,d) ovate, light amber; nucleus slightly eccentric; dorsal surface smooth. Attachment scar margin near smooth, with only faint trace between nucleus and inner edge; central callus weak.

Central radular tooth (Figure 38c) with moderately indented dorsal edge; lateral cusps, 4–5; central cusp rounded to weakly pointed, considerably broader and longer than laterals; basal cusps, 1 (although occasional weak suggestion of second cusp), elongate, with strong dorsal support. Basal process medium width; basal sockets deep. Lateral margins thickened; neck absent.

Penis (Figure 49d) small (retracted specimens); filament medium length, narrow; lobe shorter than filament. Terminal gland small, borne along distal edge of lobe (on both surfaces). Ventral gland large, positioned near distal edge of penis. Filament pigmented.

TYPE LOCALITY.—Pyrgulopsis nevadensis: Walker and Pyramid Lakes, Nevada. Subsequently restricted to Pyramid Lake, Washoe County, Nevada (per Baker, 1964:174). Lectotype, ANSP 27811; paratypes, ANSP 375739. Pyrgulopsis ecarinata: Walker and Pyramid Lakes (not restricted subsequently). Location of types not known. Pyrgulopsis pauitica: Pyramid Lake, Nevada. Holotype, ANSP 187693; paratypes ANSP 396956.

DISTRIBUTION.—Pyramid Lake (Recent); Walker Lake, Winnemucca Lake (Pleistocene?). The snail persisted in Pyramid Lake at least until the very late 1800s, as evidenced by presence in museum collections of numerous live-collected specimens from this period. Recent dredging hauls from the lake have not yielded live snails (Swain and Meader, 1958; Robertson, 1978; Galat et al., 1981), suggesting that the species now is extinct.

MATERIAL EXAMINED.—USNM 63992, Pyramid Lake, Nevada.