Tryonia ovata Hershler, Liu & Landye, 2011, sp. nov.
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 ovata

description: Tryonia ovata sp. nov.
(Figs 5 C, 7A–B, F–G, J–L)
Types. Holotype, USNM 873264, Ojos de Arrey, western-most head spring, south of Galeana, Chihuahua, 30º3'28.3" N, 107º35'26.3" W, leg. J.J.L. et al., 25/viii/1971. Paratypes (from same lot), USNM 1153676.
Referred material. CHIHUAHUA. USNM 854944, topotypes, leg. R.H. and J.J.L., 7/xii/1998. UTEP 977, Ojos de Arrey, ca. 6.4 km south of Galeana, opposite road to Ejido Horcon, leg. A. Metcalf and D.W. Taylor, 3/ix/ 1969.
Etymology. The species name is an adjective referring to the broad shell of this snail.
Diagnosis. Shell medium-sized, ovate-conic, apex usually eroded; penis having two distal and one basal papillae on the inner edge. Distinguished from sympatric T. angosturae by its more convex teleoconch whorls, presence of a basal papilla on the inner edge of the penis and absence of a basal papilla on the outer edge of the penis.
Description. Shell (Fig. 7 A–B) up to 3.9 mm tall, whorls 4.0–5.0, spire height 85–110% width of shell, sexual dimorphism of shells not obvious. Teleoconch whorls medium to highly convex, evenly rounded or narrowly shouldered, sutures deeply impressed. Aperture sometimes weakly angled adapically, parietal lip complete, usually adnate, rarely slightly disjunct, umbilicus narrow. Outer lip thin, orthocline or weakly prosocline. Sculpture of strong growth lines. Periostracum tan.
Shell measurements (mean in parentheses): height 2.71–3.06 mm (2.87), width 1.64–1.94 mm (1.74), body whorl height 1.83–2.11 mm (1.92), body whorl width 1.55–1.70 mm (1.61), aperture height 1.04–1.15 mm (1.10), aperture width 0.90–1.08 mm (0.96), total number of whorls 4.00–5.00 (4.45) (USNM 1153676, n = 5).
Measurements of holotype: height 2.89 mm, width 1.68 mm, body whorl height 1.92 mm, body whorl width 1.57 mm, aperture height 1.11 mm, aperture width 0.95 mm, 5.0 whorls.
Inner and outer sides of operculum smooth (Fig. 7 F–G). Radula (Fig. 7 J–L): dorsal edge of central radular teeth concave, basal tongue V-shaped, median cusps elongate, distally pointed, parallel-sided proximally, lateral cusps four–six, basal cusps two–three (innermost larger) (Fig. 7 K). Lateral teeth having two–three cusps on inner and three–five cusps on outer side, length of outer wing about 200% width of cutting edge, central cusp pointed (Fig. 7 L). Inner marginal teeth with 14–26 cusps, outer marginal teeth with 29–42 cusps. Radula data are from USNM 1153676.
Animal darkly pigmented. Penis (Fig. 5 C) having two distal and one basal papillae on inner edge (29/ 30 specimens); one specimen differed in having a single distal papilla. Distal bulb of penis only slightly expanded laterally on inner side, lightly pigmented; stylet small. Penial duct near straight or undulating basally. Penial data are from USNM 1153676.
Distribution and habitat. Tryonia ovata is endemic to Ojos de Arrey, a large spring complex in the Río Santa Maria basin (interior drainage) (Fig. 1, locality 5) that is situated along the northern edge of a hill (Cerro Angostura). These springs have also been referred to as La Angostura and Ojo de los Reyes. Tryonia ovata and T. angosturae (described next) snail were collected in the (southwestern) portion of the spring complex that has been developed for recreational purposes; there are several additional springs to the northeast that have not been sampled. Both species are found below the main headspring (Fig. 6 D; also see Miller et al. 2005: plate 68) on Chara and Potamogeton and in soft sediments under submerged vegetation (26–27°C water temperature).
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 9-13, DOI: 10.5281/zenodo.278442