Pyrgulopsis perforata Hershler, Liu & Bradford

Hershler, Robert, Liu, Hsiu-Ping & Bradford, Corbin, 2013, Systematics of a widely distributed western North American springsnail, Pyrgulopsis micrococcus (Caenogastropoda, Hydrobiidae), with descriptions of three new congeners, ZooKeys 330, pp. 27-52 : 33-35

Pyrgulopsis perforata Hershler, Liu & Bradford sp. n. Figs 4 C–D, 6

Pyrgulopsis micrococcus . - Hershler 1989 (in part).

Pyrgulopsis micrococcus clade B. - Liu et al. (2003).

Types.

United States: Holotype, USNM 853507 (a dry shell), easternmost spring from Scotty’s Castle along California Highway 72, Grapevine Canyon, Death Valley, Inyo County, California, 37.03233°N, 117.32333°W, 26 February 1985, R. Hershler. Paratypes, USNM 1204734 (from same lot).

Referred material.

CALIFORNIA. Inyo County: BellMNH 20891, USNM 857965, USNM 883371, USNM 883374, USNM 883375, USNM 883376, USNM 883377, USNM 894332, easternmost spring from Scotty’s Castle along CA Hwy 72, Grapevine Canyon, Death Valley, USNM 883369, spring east of Scotty’s Castle along CA Hwy 27, Grapevine Canyon, Death Valley (37.03259°N, 117.33118°W), USNM 883368, USNM 883379, spring just east of Scotty’s Castle, Grapevine Canyon, Death Valley (37.03205°N, 117.33715°W), BellMNH 20999, USNM 894333, spring ca. 0.8 km west of Scotty’s Castle along CA Hwy 72, Grapevine Canyon, Death Valley (37.01400°N, 117.34867°W), USNM 894334, Surprise Springs, Death Valley (36.99933°N, 117.34400°W).

Diagnosis.

A small to medium-sized congener (maximum shell height, 2.6 mm) having a broadly to ovate conic shell. Differentiated from similar regional species except Pyrgulopsis micrococcus by its low-spired, broadly umbilicate shell. Differs from Pyrgulopsis micrococcus in having a larger distal lobe and smaller gland on the penis.

Description.

Shell (Fig. 6 A–B) broadly to ovate conic, whorls 3.00-4.25. Teleoconch whorls medium convex, shouldered. Aperture ovate, parietal lip complete, narrowly adnate or slightly disjunct, last 0.25-0.5 whorl rarely loosened behind aperture, umbilicus broad (Fig. 6C). Outer lip thin, orthocline or prosocline.

Operculum (Fig. 6 D–E) as for genus; outer side smooth; inner side smooth or weakly thickened along portions of the muscle attachment margin. Radula (Fig. 6 F–H) as for genus; dorsal edge concave, lateral cusps four–eight, basal cusp one. Lateral teeth having two–four cusps on inner sides and three–six cusps on outer sides. Inner marginal teeth with 14-24 cusps, outer marginal teeth with 18-31 cusps. Radula data are from USNM 857965.

Penis (Fig. 4 C–D) medium-sized; filament medium length, narrow, tapering, oblique; lobe medium-sized, rectangular, horizontal or slightly oblique; small (terminal) gland present on ventral edge of lobe (60/60 specimens), one specimen had an additional dot-like gland on the ventral surface of the lobe and one specimen had a similar glandular unit on the dorsal surface of the lobe. Penial data are from BellMNH 20891, USNM 883371.

Distribution.

Lower portion of Grapevine Canyon, and Grapevine Mountains, lower Amargosa River basin (M3, M4, M5, Fig. 2). The type locality (Fig. 5 C–D) is the uppermost of a small series of springs to the east of Scotty’s Castle.

Etymology.

An adjective derived from the New Latin, perforare, meaning to pierce, and referring to the broad umbilicate shells of this species.

Remarks.

The relationships of Pyrgulopsis perforata were not well resolved in the molecular phylogenetic analysis (Fig. 1). Haplotype variation within this clade was relatively small (Appendix II).