Tryonia chuviscarae 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 chuviscarae

description: Tryonia chuviscarae sp. nov.
(Figs 5 J, 10A–C, F–G, J–L)
Types. Holotype, USNM 873270, Balneario de San Diego de Alcala, Chihuahua, 28º35'17.6" N, 105º32'50.8" W, leg. J.J.L. et al., 29/viii/1971. Paratypes (from same lot), USNM 873294, USNM 905265, 1153669.
Etymology. Epithet refers to the Río Chuviscar, which is close to the type locality of this species.
Referred material. CHIHUAHUA. USNM 854941, topotypes, leg. R.H. and J.J.L., 9/xii/1998. USNM 1001750, USNM 1001756, ibid., leg. R.H. and J.J.L., 4/xii/2001.
Diagnosis. Shell small, broadly- or ovate-conic; penis having two distal papillae on the inner edge and one–two basal papillae on the outer edge. Differentiated from sympatric T. minckleyi (described next) in its smaller shells (t-test for shell height, t = -10.699, df = 24.7, P <0.01), thickened inner lip of shell, larger umbilicus, more convex dorsal edge of central radular teeth, V-shaped basal tongue of central radular teeth, narrower central radular teeth, and square-shaped face of lateral teeth; and from conchologically similar and closely related T. julimesensis (described below) in its larger shells (t-test for shell height, t = -6.666, df = 23.8, P <0.01), in having basal papillae on the penis, and in having a larger number of cusps on the outer marginal radular teeth.
Description. Shell (Fig. 10 A–C) up to 2.5 mm tall, large females having 3.75–5.00 whorls, spire height 75–95% width of shell, male shells smaller than those of females. Teleoconch whorls high convex, frequently shouldered, sutures impressed, last 0.5 whorl sometimes loosened. Aperture usually rounded adapically, rarely weakly angled, inner lip complete, usually thickened, adnate or disjunct, umbilicus narrow or open. Outer lip thin, orthocline or prosocline, weakly sinuate. Sculpture of strong growth lines, weak spiral threads also sometimes present. Periostracum light tan or absent.
Shell measurements (mean in parentheses): height 1.80–2.17 mm (1.98), width 1.21–1.43 mm (1.31), body whorl height 1.36–1.61 mm (1.48), body whorl width 1.06–1.24 mm (1.15), aperture height 0.79–0.99 mm (0.88), aperture width 0.71–0.85 mm (0.77), total number of whorls 3.75–4.25 (4.13) (USNM 1001750, n = 12).
Measurements of holotype: height 2.28 mm, width 1.45 mm, body whorl height 1.66 mm, body whorl width 1.31 mm, aperture height 0.98 mm, aperture width 0.79 mm, 4.5 whorls.
Outer side of operculum smooth (Fig. 10 F), portion of attachment scar margin slightly thickened on inner side (Fig. 10 G). Radula (Fig. 10 J-L): dorsal edge of central radular teeth strongly concave, basal tongue V-shaped, median cusps distally pointed, parallel-sided proximally, lateral cusps four–six, basal cusps two–three (outermost larger) (Fig. 10 K). Lateral teeth having two–four cusps on inner and three–six cusps on outer sides, length of outer wing about 140% width of cutting edge, central cusp pointed (Fig. 10 L). Inner marginal teeth having 18–24 cusps, outer marginal teeth having 20–28 cusps. Radula data are from USNM 1001750.
Animal darkly pigmented. Penis (Fig. 5 J) having two distal papillae on the inner edge and one–two basal papillae on the outer edge (27 of 30 specimens), two specimens differed in also having a basal papilla on the inner edge. Distal bulb of penis expanded laterally on inner side, black; stylet large. Penial duct straight or weakly undulating along most of length. Penial data are from USNM 1001756.
Distribution and habitat. Endemic to the type locality in the Río Conchos basin (Fig. 1, locality 9). This site, which is also known as Baños de San Diego de Alcala, is a warm spring complex (headspring temperatures ca. 42–45°C) that has long been used for recreation. Numerous springs discharge from a travertine mound (where a large bathhouse is situated) on the western edge of the complex (Fig. 6 L–M). Tryonia chuviscarae and T. minckleyi were found throughout the spring complex (except in the headspring vents) on mud and gravel; the highest temperature recorded for this snail habitat was 41°C.
Remarks. The occurrence of undescribed Tryonia in the Balneario de San Diego de Alcala was noted by Minckley & Minckley (1986), however it is not clear whether they were referring to T. chuviscarae, T. minckleyi, or both. Tryonia chuviscarae was delineated as a well supported lineage in the Bayesian tree (Fig. 2).
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 21-23, DOI: 10.5281/zenodo.278442