Pyrgulopsis marilynae Hershler, Ratcliffe, Liu, Lang and Hay

Hershler, Robert, Ratcliffe, Victoria, Liu, Hsiu-Ping, Lang, Brian & Hay, Claire, 2014, Taxonomic revision of the Pyrgulopsis gilae (Caenogastropoda, Hydrobiidae) species complex, with descriptions of two new species from the Gila River basin, New Mexico, ZooKeys 429, pp. 69-85 : 74-76

Taxon classification Animalia ORDO Hydrobiidae

Pyrgulopsis marilynae Hershler, Ratcliffe, Liu, Lang and Hay sp. n. Figs 3, 4 A–B

Pyrgulopsis gilae (clade II).-Liu et al. 2013.

Types.

Holotype, USNM 1135068 (a dry shell), spring 0.48 km north, 0.48 km west of Jordan Canyon, Catron County, New Mexico, 33.2909°N, 108.2681°W, 1 October 2009, Michelle Christman. Paratypes, USNM 1231474 (from same lot).

Referred material.

NEW MEXICO. Catron County: USNM 1123432, USNM 1123588, spring 0.8 km north, 0.64 km west of Jordan Canyon (33.2889°N, 108.2683°W), USNM 1135067, spring 0.97 km north, 0.64 km west of Jordan Canyon (33.2924°N, 108.2696°W), USNM 883175, Jordan Hot Spring (33.2927°N, 108.2692°W).

Diagnosis.

Distinguished from Pyrgulopsis gilae and the species described next ( Pyrgulopsis similis ) by its narrower shell (mean shell width/shell height 0.613 vs. 0.682, t=-9.6588, df=36.2176, P<0.0001, n=30 for Pyrgulopsis gilae ; 0.613 vs. 0.734, t=-16.3617, df=18.9656, P<0.0001, n=11 for Pyrgulopsis similis ), more pronounced whorl shoulders, and broad overlap of the ventral surface of the penis by the terminal gland (probably reflecting fusion with a distal ventral gland). Further differs from Pyrgulopsis gilae in its smaller size (mean shell height 2.77 vs. 3.47 mm, t=-11.3848, df=21.9544, P<0.0001) and (basal) extension of the outer penial gland to mid-line or left edge of penis. Further differs from Pyrgulopsis similis in its larger size (mean shell height 2.77 vs. 2.36 mm, t=7.3691, df=15.3701, P<0.0001), smaller number of dorsal glands on the penis, and larger size of the terminal and ventral glands on the penis.

Description.

Shell (Fig. 3 A–B) narrow-conic, whorls 4.5-5.0. Teleoconch whorls convex, shoulders narrow, angular, sutures impressed. Aperture ovate, angled above, parietal lip complete, usually slightly disjunct, umbilicus narrow. Outer lip thin, orthocline.

Operculum (Fig. 3 C–D) as for genus; edges of last 0.5 whorl weakly frilled on outer side; portion of muscle attachment margin thickened on inner side. Radula (Fig. 3 E–G) as for genus; dorsal edge of central teeth concave, lateral cusps four–five, basal cusp one. Lateral teeth having two–three cusps on both inner and outer sides. Inner marginal teeth with 14-20 cusps, outer marginal teeth with 17-22 cusps. Radula data are from USNM 1135067.

Penial filament and penial lobe about equal in length (Fig. 4 A–B). Filament having two (penial) glands on dorsal surface; inner gland shorter. Outer penial gland curving to mid-line (10/24 specimens) or left edge of penis (14/24 specimens), the latter condition probably represents fusion with a gland on the left edge (Dg2). Terminal gland elongate, horizontal, broadly overlapping ventral surface of penis. Dorsal surface of penis having gland along right edge of lobe (Dg3) and 2-3 additional glands (22/24 specimens); one specimen did not have any additional glands and one specimen had four additional glands. Ventral gland positioned near centrally. Penial data are from USNM 1135067.

Etymology.

The specific epithet is a patronym honoring Marilyn Myers (United States Fish and Wildlife Service, retired) for her dedicated efforts to survey Pyrgulopsis habitats in the upper Gila River basin.

Distribution.

A series of seeps and springs along the north side of short reach (ca. 0.25 km) of the Middle Fork Gila River just below Jordan Hot Spring (Fig. 1). The type locality is a seep wall which is the lower-most occurrence of Pyrgulopsis marilynae along the Middle Fork Gila River; the water temperature at this site was 25°C on 1 October 2009.

Remarks.

Pyrgulopsis marilyane was resolved as sister to Pyrgulopsis gilae (100% posterior probability) in the molecular phylogenetic analysis (Fig. 2). The apparent fusion of the terminal and distal ventral glands of the penis that characterizes this species (in part) was previously reported for Pyrgulopsis sadai ( Hershler 1998, fig. 39I). The sample attributed to Jordan Hot Spring (USNM 883175) may have been collected instead from a closely proximal spring as Pyrgulopsis gilae has not been found at the former locality during recent surveys ( USFWS 2011b).