Pyrgulopsis aardahli Hershler 1989

Pyrgulopsis aardahli Hershler, 1989

Pyrgulopsis aardahli Hershler, 1989:179, figs. 10–14.

DIAGNOSIS.—Shell ovate to broadly conical, medium-sized, umbilicate. Penial filament short, lobe very small. Penial ornament a weak, dot-like Dg1; small, circular terminal gland; and stalked ventral gland.

DESCRIPTION.—Shell (Figure 7a) ovate to broadly conical; height, 2.6–3.4 mm; whorls, 4. Protoconch very weakly punctate. Teleoconch whorls convex, slightly shouldered; sculpture of faint growth lines. Aperture ovate, narrowly adnate to or slightly separated from body whorl. Inner lip complete, medium thickness; columellar lip very slightly reflected. Outer lip slightly prosocline. Umbilicus rimate to open. Periostracum light brown.

Operculum (Figure 7b,c) broadly ovate, light amber, nucleus slightly eccentric; dorsal surface strongly frilled. Attachment scar margin well thickened all around (broadly so along most of perimeter). Callus well developed.

Central radular tooth (Figure 32a) with moderately indented dorsal edge; lateral cusps, S; central cusp rounded, considerably broader and slightly longer than laterals; basal cusps, 1, short, narrowly triangular, with moderate dorsal support. Basal process broad; basal sockets deep. Lateral margins thickened; neck weak.

Snout dark gray-black; neck variably pigmented. Cephalic tentacles pale other than a light gray patch proximal to eyespots. Pigment sometimes concentrated along anterior edge of foot and margins of opercular lobe. Palliai roof, visceral coil dark brown-black.

Ctenidial filaments, 23, tall, broad. Osphradium elongate (33%), centered well posterior to middle of ctenidial axis. Kidney opening white. Stomach caecum finger-like.

Testis, 1.5 whorls, overlapping stomach to edge of style sac. Prostate gland bean-shaped to near-circular, palliai section short. Palliai vas deferens weakly kinked proximally. Penis (Figure 43a) large, extending slightly beyond mantle edge; filament short, narrow, tapering; lobe short, narrow (sometimes absent). Dg1 dot-like, sometimes absent, positioned near mid-line. Terminal gland small, circular-transverse, borne on ventral surface distally (sometimes absent). Ventral gland large, elongate, borne on prominent swelling. Proximal penial filament with dark internal pigment.

Ovary, 1 whorl, overlapping posterior stomach. Palliai albumen gland short. Capsule gland slightly shorter than albumen gland. Genital aperture a broad terminal slit with very short vestibule. Coiled oviduct a short horizontal twist overlapping a near circular loop. Oviduct and bursal duct join just behind palliai wall. Bursa copulatrix ovoid, medium length and width, with about 50% of length posterior to albumen gland. Bursal duct narrow, slightly shorter than bursa copulatrix, partly embedded in albumen gland anteriorly. Seminal receptacle finger-like, usually folded, short, overlapping bursal duct.

TYPE LOCALITY.—Spring, Bramlette Ranch, Benton Valley, Mono County, California (T IS, R 32E, SW1/4 sec. 6). Holotype, USNM 860406; paratypes, USNM 857951.

DISTRIBUTION.—Known only from type locality, upper Owens River drainage.

MATERIAL EXAMINED.—USNM 857951 (paratypes).

Pyrgulopsis aardahli, commonly known as the Benton Valley springsnail, is a species of freshwater snails in the family Hydrobiidae.

This species' natural habitat is springs. It is endemic to a spring on the Bramlette Ranch, Mono County, California, United States.