Tryonia allendae 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 allendae

description: Tryonia allendae sp. nov.
(Figs 5 M, 11D–E, H–I, M– O)
Tryonia n. sp. 4.— Hershler et al. 2005: 1757 (COI sequence).
Types. Holotype, USNM 892115, El Ojito, southwest of Talamantes, Chihuahua, 26º54'12.6" N, 105º27'19.8" W, leg. R.H. and J.J.L., 10/xii/1998. Paratypes (from same lot), USNM 1153667.
Etymology. A geographic epithet referring to the municipality of Allende in which this species is distributed.
Diagnosis. Shell medium-sized, ovate-conic or conic; penis having two distal papillae on the inner edge and a basal papilla on the outer edge. Contrasted with conchologically similar T. minckleyi above. Differentiated from T. chuviscarae and T. julimesensis, which are also distributed in the Río Conchos basin, in having a more strongly undulating penial duct.
Description. Shell (Fig. 11 D–E) up to 5.8 mm tall, large females having 5.0–5.75 whorls, spire height 110–140% width of shell, male shells smaller than those of females. Teleoconch whorls weak to medium convex, evenly rounded, sutures impressed. Aperture angled adapically, parietal lip complete, usually adnate, rarely slightly disjunct, umbilicus narrow or absent. Outer lip thin, orthocline. Sculpture of strong growth lines, weak spiral thread also sometimes present. Periostracum tan.
Shell measurements (mean in parentheses): height 2.69–3.66 mm (2.92), width 1.40–1.76 mm (1.53), body whorl height 1.64–2.20 mm (1.82), body whorl width 1.23–1.67 mm (1.43), aperture height 0.94–1.22 mm (1.06), aperture width 0.82–1.06 mm (0.89), total number of whorls 5.00–5.75 (5.35) (USNM 1153667, n = 15).
Measurements of holotype: height 2.91 mm, width 1.44 mm, body whorl height 1.72 mm, body whorl width 1.35 mm, aperture height 0.97 mm, aperture width 0.83 mm, 5.5 whorls.
Outer side of operculum smooth (Fig. 11 H), inner side smooth or with edges of last 0.5 whorl weakly frilled (Fig. 11 I). Radula (Fig. 11 M-O): dorsal edge of central radular teeth concave, basal tongue rounded, median cusps distally pointed, parallel-sided proximally, lateral cusps four–six, basal cusps one–two (innermost larger) (Fig. 11 N). Lateral teeth having two–three cusps on inner and three–four cusps on outer sides, length of outer wing about 150% width of cutting edge, central cusp pointed (Fig. 11 O). Inner marginal teeth having 20–26 cusps, outer marginal teeth having 22–40 cusps. Radula data are from USNM 1153677.
Animal lightly pigmented. Penis (Fig. 5 M) having two distal papillae on inner edge and a basal papilla on outer edge (30 of 30 specimens). Distal bulb of penis expanded laterally on inner side, black. Penial duct strongly undulating along most of length; stylet small. Penial data are from USNM 1153667.
Distribution and habitat. Endemic to a single site (El Ojito) in an upper reach of the Río Conchos watershed (Fig. 1, locality 11). The springs at this locality have been impounded with a concrete dam for recreational purposes (Edwards et al. 2003). Tryonia allendae was abundant (on rootlets and dead leaves) in the outflow (25°C) of the impoundment (Fig. 6 O).
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 page 26, DOI: 10.5281/zenodo.278442