Pyrgulopsis similis 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 : 76-79

Taxon classification Animalia ORDO FAMILIA

Pyrgulopsis similis Hershler, Ratcliffe, Liu, Lang and Hay sp. n. Figs 4 C–D, 5

Pyrgulopsis gilae .- Hurt 2004 (in part; Wall Lake population).

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

Types.

United States: Holotype, USNM 1135064 (a dry shell), spring along Beaver Creek, ca. 0.29 km north and 0.4 km west of confluence with Taylor Creek, Catron County, New Mexico, 33.3405°N, 108.1097°W, 21 May 2009, BKL and Marilyn Myers. Paratypes, USNM 1135065, 1231475 (from same lot).

Referred material.

NEW MEXICO. Catron County: USNM 854684, USNM 1135057, USNM 1123589, USNM 1135058, USNM 1135059, Fall Spring, 1.61 km north, 0.56 km east of Burnt Corral Canyon (33.294°N, 108.1302°W), USNM 1123590, hillside seep 1.61 km north, 0.97 km east of Burnt Corral Canyon (33.2951°N, 108.1268°W), USNM 854685, USNM 1123594, USNM 1135060, USNM 1135061, seepage along Taylor Creek, ca. 0.32 km south, 0.93 km west of Wall Lake dam (33.3457°N, 108.0904°W), USNM 854683, USNM 1123592, USNM 1135062, USNM 1135063, spring along Taylor Creek, ca. 0.81 km north, 1.13 km east of Wall Lake Dam (33.3581°N, 108.0673°W), USNM 854682, USNM 1123593, NM: Catron Co., seepage along Taylor Creek, ca. 50 m west of Whitetail Canyon (33.3613°N, 108.0576°W).

Diagnosis.

Differs from Pyrgulopsis gilae in its smaller size (mean shell height 2.36 vs. 3.47 mm, t=--22.7297, df=36.4071, P<0.0001, n=30 for Pyrgulopsis gilae ), larger number of glands on the dorsal surface of the penis, frequent extension of outer penial gland and/or Dg2 to the mid-line of the penis, and smaller size of the terminal and ventral glands on the penis. Contrasted with Pyrgulopsis similis above.

Description.

Shell (Fig. 5 A–B) ovate- to narrow conic, whorls 3.75-4.50. Teleoconch whorls medium convex, narrowly shouldered. Aperture pyriform, parietal lip complete, usually adnate, sometimes slightly disjunct, umbilicus small. Outer lip thin, orthocline.

Operculum (Fig. 5 C–D) as for genus; edges of last 0.5 whorl frilled on outer side; inner side near smooth. Radula (Fig. 5 E–G) as for genus; dorsal edge of central teeth concave, lateral cusps four–six, basal cusp one. Lateral teeth having two–three cusps on inner sides and two–four cusps on outer sides. Inner marginal teeth with 15 -20 cusps, outer marginal teeth with 16-25 cusps. Radula data are from USNM 1135059, USNM 1135064.

Penial filament longer than lobe (Fig. 4 C–D). Filament having two (penial) glands on dorsal surface; inner gland shorter. Outer penial gland sometimes extending (basally) to mid-line (4/30 specimens) or left edge (7/30 specimens); Dg2 sometimes curving (basally) to mid-line (11/30 specimens). Terminal gland transverse, rather small. Dorsal surface of penis having gland along right edge of lobe (Dg3) and 3-7 additional glands (30/30 specimens) which form long, slightly oblique strips. Ventral gland small, positioned near centrally; second gland rarely present (4/30 specimens). Penial data are from USNM 1135065.

Distribution.

Springs along a short reach (ca. 10 km) of the East Fork Gila River from just above Wall Lake to slightly above the mouth of Burnt Corral Canyon (Fig. 1). The type locality is a spring brook (ca. one m wide and 0.25 m deep) that discharges at the base of the canyon wall along the east side of Beaver Creek; the water temperature at this locality was 22.1°C on 21 May 2009. The flow at this locality is augmented by numerous small seeps.

Etymology.

The specific epithet is an adjective referring to the close resemblance between this species and both Pyrgulopsis gilae and Pyrgulopsis marilynae .

Remarks.

Pyrgulopsis similis was resolved as sister to the clade composed of P. marilynae and Pyrgulopsis gilae (100% posterior probability) in the Bayesian analysis of molecular data (Fig. 2).