Tryonia julimesensis Hershler, Liu & Landye, 2011, new species
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 julimesensis

description: Tryonia julimesensis new species
(Figs 5 L, 11A–C, F–G, J–L)
Types. Holotype, USNM 874130, unnamed springs along east side of Río Conchos, south-southeast of Julimes, Chihuahua, 28º24'37.2" N, 105º25'21.6 " W, leg. J.J.L. et al., 5/v/1991. Paratypes (from same lot), USNM 1153671.
Etymology. A geographic epithet referring to the distribution of this species near the town of Julimes, Chihuahua.
Referred material. CHIHUAHUA. USNM 854940, topotype, R.H. and J.J.L., 9/xii/1998.
Diagnosis. Shell small, broad- or ovate-conic; penis having two distal papillae on the inner edge. Contrasted with T. chuviscarae and T. minckleyi above.
Description. Shell (Fig. 11 A–C) up to 2.0 mm tall, large females having 4.00–4.50 whorls, spire height 80–99% width of shell, male shells smaller than those of females. Teleoconch whorls high convex, frequently shouldered, sutures impressed, last 0.25 whorl sometimes loosened. Aperture usually rounded adapically, rarely weakly angled, inner lip complete, slightly thickened, adnate or disjunct, umbilicus narrow or open. Outer lip thin, orthocline or prosocline, weakly sinuate. Sculpture of strong growth lines, weak spiral thread also sometimes present. Periostracum light tan.
Shell measurements (mean in parentheses): height 1.54–1.98 mm (1.69), width 1.03–1.21 mm (1.09), body whorl height 1.15–1.34 mm (1.21), body whorl width 0.92–1.07 mm (0.97), aperture height 0.66–0.79 mm (0.71), aperture width 0.61–0.71 mm (0.65), total number of whorls 4.00–4.50 (4.18) (USNM 1153671, n = 15).
Measurements of holotype: height 1.90 mm, width 1.24 mm, body whorl height 1.34 mm, body whorl width 1.07 mm, aperture height 0.81 mm, aperture width 0.69 mm, 4.25 whorls.
Inner and outer sides of operculum smooth (Fig. 11 F–G). Radula (Fig. 11 J-L): dorsal edge of central radular teeth strongly concave, basal tongue rounded or V-shaped, median cusps distally pointed, parallel-sided proximally, lateral cusps four–five, basal cusps one–three (roughly equal-sized) (Fig. 11 K). Lateral teeth having three–four cusps on inner and four–five cusps on outer sides, length of outer wing about 160% width of cutting edge, central cusp pointed (Fig. 11 L). Inner marginal teeth having 16–21 cusps, outer marginal teeth having 15–20 cusps. Radula data are from USNM 1153671.
Animal darkly pigmented. Penis (Fig. 5 L) having two distal papillae on the inner edge (26 of 30 specimens), four specimens differed in having a single distal papilla. Distal bulb of penis expanded laterally on inner side, black; stylet large. Penial duct weakly undulating in medial section. Penial data are from USNM 1153671.
Distribution and habitat. Endemic to the type locality, a warm spring complex along the east side of the Río Conchos (Fig. 1, locality 10). Tryonia julimesensis was abundant (on hard substrate and in detritus) in the main spring runs (44°C) (Fig. 6 N) when first discovered in 1991. It was also found in a small rheocrene just to the west of the main spring pools (44°C) as well as in semi-aquatic habitats on exposed rootlets and stones. When visited in 2001 the springs had been draglined (excavated) and T. julimensis could not be found. We presume that this species is now extinct.
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 24, DOI: 10.5281/zenodo.278442