New species and records of springsnails (Caenogastropoda: Cochliopidae: Tryonia) from the Chihuahuan Desert (Mexico and United States), an imperiled biodiversity hotspot Author Hershler, Robert Author Liu, Hsiu-Ping Author Landye, Jerry text Zootaxa 2011 3001 1 32 journal article 10.5281/zenodo.278442 6b9505e0-ac6e-4baa-9066-6f729d38e9e2 1175-5326 278442 Tryonia zaragozae sp. nov. ( Figs 4 E–G, J–L, P–R, 5B) Tryonia n. sp. 2.— Hershler et al . 2005 : 1757 (COI sequence). Types . Holotype , USNM 873286, springs ca. 4.8 km north-east of Ignacio Zaragoza along the south side of Highway 5, Chihuahua, 29º39'47.9" N , 107º44'25.8" W , leg. J.J.L. et al ., 25/viii/1971 . Paratypes (from same lot), USNM 873260, USNM 873289, USNM 874120, USNM 1153679. Etymology . The species name is a geographic epithet referring to the nearby town of Ignacio Zaragoza. Referred material . CHIHUAHUA. USNM 854942, topotypes, leg. R.H. and J.J.L., 8/xii/1998 . Diagnosis. Shell medium-sized, conic or turriform, apex usually eroded; penis having two distal papillae on inner edge and a basal papilla both on the inner and outer edges. Contrasted with T. peregrina above. Description . Shell ( Fig. 4 E–G) up to 6.7 mm tall, whorls 6.5–8.75, spire height 150–200% width of shell, sexual dimorphism of shells not obvious. Teleoconch whorls weakly convex to almost flat, evenly rounded or, less frequently, narrowly shouldered, with adpressed sutures. Aperture sharply angled adapically, parietal lip usually incomplete, usually adnate when complete, rarely slightly disjunct, umbilicus absent. Outer lip thin, orthocline or weakly prosocline. Sculpture of strong growth lines and well developed spiral threads ( Fig. 4 L). Periostracum tan. Shell measurements ( mean in parentheses): height 3.85–4.65 mm (4.20), width 1.60–1.78 mm (1.69), body whorl height 2.10–2.41 mm (2.21), body whorl width 1.53–1.67 mm (1.60), aperture height 1.23–1.41 mm (1.31), aperture width 0.91–1.08 mm (0.99), total number of whorls 6.50–7.25 (6.78) (USNM 1153679, n = 15). Measurements of holotype : height 4.39 mm , width 1.68 mm , body whorl height 2.30 mm , body whorl width 1.60 mm , aperture height 1.35 mm , aperture width 1.01 mm , 7.25 whorls. Edges of last operculum whorl strongly frilled on outer side ( Fig. 4 J); muscle attachment scar margins somewhat thickened on inner side of operculum ( Fig. 4 K). Radula ( Fig. 4 P-R): dorsal edge of central radular teeth concave, basal tongue rounded or V-shaped, median cusps elongate, distally pointed, parallel-sided proximally, lateral cusps five–six, basal cusps two–three (innermost larger) ( Fig. 4 Q). Lateral teeth having two–three cusps on inner and four–six cusps on outer side, length of outer wing 175–200% width of cutting edge, central cusp pointed ( Fig. 4 R). Inner marginal teeth with 24–35 cusps, outer marginal teeth with 30–40 cusps. Radula data are from USNM 1153679. Animal darkly pigmented. Penis ( Fig. 5 B) having two distal papillae on inner edge and a basal papilla both on the inner and outer edges (30 of 30 specimens ). Papilla on outer edge sometimes very small. Distal bulb of penis expanded laterally on inner side, lightly pigmented; stylet small. Penial duct undulating for most of length. Penial data are from USNM 1153679. Distribution and habitat. Tryonia zaragozae is known only from its type locality, a large (ca. 0.01 km 2) cienega and spring system ( Fig. 6 C) in the upper Río Casas Grandes drainage ( Fig. 1 , locality 4). Snails were collected (on gravel and on soft substrates) from several springs and bogs (29–30°C) within this cienega. This habit has been severely degraded by overgrazing in recent years, although one of the larger head springs is now fenced (first noted in 1998).