Tryonia taylori 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 taylori

description: Tryonia taylori sp. nov.
(Figs 5 G–H, 9A–D, G–I, L–N)
Types: Holotype, USNM 873254, ouflow of Ojo Caliente at Rancho Ojo Caliente, south of Highway 10, Chihuahua, 29º54'10.2" N, 107º15'27.1" W, leg. J.J.L. et al., 27/viii/1971. Paratypes (from same lot), USNM 1153678.
Etymology. A patronym honoring the late Dwight W. Taylor for his pioneering taxonomic studies of Tryonia (Taylor 1987).
Referred material. CHIHUAHUA. USNM 873251, topotypes, leg. J.J.L. et al., 27/viii/1971. USNM 874047, topotypes, leg. J.J.L. and P. Hines, 18/ix/1990. USNM 1135493, topotypes, R.H. and J.J.L., 7/xii/1998. USNM 873283, El Ojo de Servin, 5.6 km west of Rancho Ojo Caliente, 0.2 km north of Highway 10, 29º54'17.2" N, 107º18'27.2" W, leg. J.J.L., 14/iv/1973. USNM 873252, USNM 873297, ibid, leg. J.J.L. et al., 27/viii/1971. USNM 874050, ibid., leg. J.J.L., 18/ix/1990. USNM 892118, ibid., leg. R.H. and J.J.L., 7/xii/1998. UTEP 978, ibid., leg. A. Metcalf and D.W. Taylor, 4/ix/1969. BellMNH 21172, BellMNH 21173, ibid., leg. D.W. Taylor and A. Metcalf, 4/ix/1969.
Diagnosis. Shell medium- to large-sized, conic or elongate-conic; penis having two distal papillae on inner edge and sometimes two–four basal papillae on inner edge and/or dorsal surface. Differentiated from closely similar T. molinae above.
Description. Shell (Fig. 9 A–D) up to 6.7 mm tall, whorls ca. 5.50–8.75, spire height 135–220% width of shell, male shells smaller than those of females. Teleoconch whorls usually weak to medium convex, rarely high convex, evenly rounded or weakly shouldered with impressed or adpressed sutures. Aperture weakly or sharply angled adapically, parietal lip usually complete, usually adnate, rarely slightly disjunct, umbilicus narrow or absent. Outer lip sometimes slightly thickened adapically, orthocline or weakly prosocline. Sculpture of strong growth lines and weak spiral threads. Periostracum tan.
Shell measurements (mean in parentheses): height 3.42–4.25 mm (3.74), width 1.54–1.84 mm (1.67), body whorl height 1.93–2.22 mm (2.09), body whorl width 1.46–1.73 mm (1.59), aperture height 1.03–1.33 mm (1.22), aperture width 0.89–1.09 mm (1.00), total number of whorls 5.50–6.50 (6.00) (USNM 1153678, n = 15).
Measurements of holotype: height 3.74 mm, width 1.59 mm, body whorl height 2.16 mm, body whorl width 1.55 mm, aperture height 1.24 mm, aperture width 1.01 mm, 6.0 whorls.
Outer side of operculum smooth (Fig. 9 G) or with edges of last 0.5 whorl frilled; inner side of operculum nearly smooth (Fig 10 H) or with edges of muscle attachment scar thickened (Fig. 9 I). Radula (Fig. 9 L-N): dorsal edge of central radular teeth concave, basal tongue rounded, median cusps elongate, distally pointed, lateral cusps four–seven, basal cusps one–three (innermost larger) (Fig. 9 M). Lateral teeth having two–five cusps on inner and three–seven cusps on outer side, length of outer wing 160–200% width of cutting edge, central cusp pointed (Fig. 9 N) or jagged-edged. Inner marginal teeth with 19–32 cusps, outer marginal teeth with 25–49 cusps. Radula data are from USNM 873283, USNM 1153678.
Animal darkly pigmented. Penis (Fig. 5 G–H) usually having two distal papillae on inner edge (46 of 56 specimens from two samples), eight specimens differed in having three distal papillae and two differed in having a single distal papilla. Ojo Caliente specimens usually lacking basal penial papillae (25 of 27 specimens), one specimen differed in having a basal papilla both on the inner and outer edges, one specimen differed in having two dorsally positioned basal papillae. Ojo de Servin specimens usually having two–three dorsally positioned basal penial papillae (27 of 29 specimens) and sometimes also having a basal papilla on the inner edge (12 of 29 specimens); one specimen had four dorsally positioned papillae and one specimen lacked basal papillae. Distal bulb of penis evenly rounded or expanded laterally on inner side, black; stylet small. Penial duct nearly straight to strongly undulating along most of length. Penial data are from USNM 873251, USNM 873252.
Distribution and habitat. Narrowly endemic in the Río Santa Maria drainage (Fig. 1, locality 7). The type locality (Ojo Caliente) is a thermal spring (36–39°C) that is enclosed in a bath house (Fig. 6 H). Tryonia taylori was found on mud, rocks and aquatic vegetation in the outflow 5–6 meters below the bath house. We did not discern a marked change in this spring from 1971–1998. The second locality, El Ojo de Servin, is a warm spring complex (23–26°C) about 5 km west of Ojo Caliente. Tryonia taylori is extremely abundant on algae and Chara in the headspring area and somewhat less common in shallow portions of the spring runs on mud. This formerly lush cienega (as observed in 1971, Fig. 6 I) is now severely overgrazed (Fig. 6 J).
Remarks. The two populations of T. taylori formed a strongly supported clade in the Bayesian tree (Fig. 2). These populations differ in shell size (3.7 vs. 5.8 mm mean shell height, t-test, t = -13.811, df = 18.6, P <0.01, n=13 for the El Ojo de Servin sample), teleoconch whorl convexity, number of cusps on the outer marginal teeth, and the number and arrangement of basal papillae on the penis. However, they do not form reciprocally monophyletic clades in the Bayesian tree and their sequence divergence ranged from 0.3 to 1.7% (Table 2). We treat these morphologically distinctive populations as conspecific based on the evolutionary lineage concept used herein.
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 18-19, DOI: 10.5281/zenodo.278442