Tryonia contrerasi Hershler, Liu & Landye, 2011, new species
Creators: name: Hershler, Robert
name: Liu, Hsiu-Ping
name: Landye, Jerry
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Gastropoda
Littorinimorpha
Hydrobiidae
Tryonia
Tryonia contrerasi

description: Tryonia contrerasi new species
(Figs. 5 F, 8D–F, I–J, N–P)
Types. Holotype, USNM 874121, Ojo del Apache, south of Rancho Nuevo, Chihuahua, 30º34'27" N, 106º54'27" W, leg. J.J.L. and D. Wong, 2/iv/1991. Paratypes (from same lot), USNM 1153670.
Etymology. A patronym honoring Salvador Contreras-Balderas (Professor Emeritus, Department of Biology, Universidad Autonoma de Nuevo Leon, Monterrey, Mexico) for his dedicated efforts over many years to promote the conservation of Chihuahuan Desert aquatic biota.
Referred material. CHIHUAHUA. USNM 854951, topotypes, R.H. and J.J.L., 14/xii/1998. UTEP 881, ca. 4 km southwest of Hacienda Santo Domingo, leg. W. Strain, no date. USNM 854124, USNM 874124, USNM 874128, Ojo Carbonero, southeast of Rancho Nuevo, Chihuahua, 30º34'47.5" N, 106º52'26" W, leg. J.J.L. and D. Wong, 2/iv/1991. USNM 854952, ibid., leg. R.H. and J.J.L., 14/xii/1998.
Diagnosis. Shell medium-to large-sized, conic, rather strongly sculptured; penis having two distal and one basal papillae on the inner edge. Distinguished from other regional congeners by its more strongly sculptured shell. Further differentiated from conchologically similar T. molinae by its larger size (t-test for shell height, t = 8.892, df = 8.892, P <0.01) and evenly rounded distal bulb of the penis; and from T. ovata, which has closely similar penial morphology, by its less convex teleoconch whorls, typically incomplete parietal lip and smaller umbilicus.
Description. Shell (Fig. 8 D–F) up to 6.2 mm tall, large females having 5.75–8.75 whorls, spire height 140–200% width of shell, male shells smaller than those of females. Teleoconch whorls weak to medium convex, evenly rounded with impressed sutures. Sculpture of widely spaced collabral riblets or cords and more numerous spiral threads or cords, sometimes resulting in a cancellate appearance. Aperture strongly angled adapically, parietal lip usually incomplete or a thin glaze across the parietal wall, rarely complete and adnate or slightly disjunct, umbilicus narrow or absent. Outer lip slightly orthocline or prosocline. Periostracum brown or tan.
Shell measurements (mean in parentheses): height 4.39–6.13 mm (4.92), width 1.85–2.25 mm (2.02), body whorl height 2.39–2.97 mm (2.62), body whorl width 1.71–2.09 mm (1.89), aperture height 1.42–1.71 mm (1.56), aperture width 1.08–1.26 mm (1.15), total number of whorls 5.75–7.75 (6.54) (USNM 1153670, n = 13).
Measurements of holotype: height 5.22 mm, width 2.21 mm, body whorl height 2.90 mm, body whorl width 2.03 mm, aperture height 1.69 mm, aperture width 1.27 mm, 6.5 whorls.
Edges of last 0.5 operculum whorl sometimes frilled on outer side (Fig. 8 I), inner side of operculum smooth (Fig. 8 J). Radula (Fig. 8 N-P): dorsal edge of central radular teeth concave, basal tongue rounded, median cusps elongate, distally pointed, parallel-sided proximally, lateral cusps four–seven, basal cusps one–three (innermost larger) (Fig. 8 O). Lateral teeth having two–four cusps on inner and three–five cusps on outer side, length of outer wing about 180% width of cutting edge, central cusp hoe-shaped (Fig. 8 P). Inner marginal teeth with 16–25 cusps, outer marginal teeth with 30–40 cusps. Radula data are from USNM 874128, USNM 1153670.
Animal darkly pigmented. Penis (Fig. 5 F) having two distal papillae and one basal papilla on inner edge (56 of 57 specimens from two samples); one specimen differed in lacking a basal papilla. Distal bulb of penis evenly rounded; stylet small. Penial duct weakly undulating along most of length. Penial data are from USNM 874128, USNM 1153670.
Distribution and habitat. Tryonia contrerasi is distributed in two closely proximal (ca. 3 km) springs in the (endorheic) Bolson de los Muertos (Fig. 1, locality 8). These springs are part of a complex to the west of Villa Ahumada near Rancho Nuevo. All of these springs with the exception of Ojo Carbonero (referred to as Ojo Carbonera by Miller et al. 2005) have been highly modified. The type locality, Ojo del Apache, is a thermal spring (27°C) that has been severely degraded (trampled) by horses (Fig. 6 F). Snails were found in this spring on aquatic vegetation. Ojo Carbonero contains at least eight discrete sources that coalesce into a spring run for about 100 m (Fig. 6 G) before flowing into a canal. Snails were common in this thermal (26–27°C) spring both in detritus and on sand. UTEP 881, which consists of old, worn shells, may have been collected from a playa lake (Laguna Colorada) along the highway southwest of Hacienda Santo Domingo.
Remarks. Tryonia contrerasi was delineated in the Bayesian analysis as a well supported lineage (Fig. 2). Snails from Ojo Carbonero (Fig. 8 E–F) are slightly smaller and have more highly sculptured shells than those from the type locality (Fig. 8 D); these two populations differed by 0.6% COI divergence.
description: Published as part of Hershler, Robert, Liu, Hsiu-Ping & Landye, Jerry, 2011, New species and records of springsnails (Caenogastropoda: Cochliopidae: Tryonia) from the Chihuahuan Desert (Mexico and United States), an imperiled biodiversity hotspot, pp. 1-32 in Zootaxa 3001 on pages 16-18, DOI: 10.5281/zenodo.278442