Pyrgophorus thompsoni, Grego, Jozef, Angyal, Dorottya & Beltran, Luis Arturo Lievano, 2019

Grego, Jozef, Angyal, Dorottya & Beltran, Luis Arturo Lievano, 2019, First record of subterranean freshwater gastropods (Mollusca, Gastropoda, Cochliopidae) from the cenotes of Yucatan state, Subterranean Biology 29, pp. 79-88 : 82-84

Pyrgophorus thompsoni sp. n. Figures 11-16

Diagnosis.

Compared to the most closely related Pyrgophorus coronatus (L. Pfeiffer, 1840), found in other cenotes and surface waters of Yucatán (Figs 17-19), the new species differs by its smaller and more pyramidal shell shape with blunter apex and finer surface sculpture, whitish periorostracum, flat protoconch and less numerous whorls, more opened umbilicus, smaller and more numerous nodules and different shape of the aperture with a characteristic sinuation at its columellar edge.

Type locality. Mexico, Yucatán state, Cenotillo Municipality, Cenote Xoch, at 46 m deep by SCUBA, buried in cave sediments, 20,997565°N; 87,936659°W.

Type material.

Holotype, Type locality: leg. Angyal and Liévano, 5 Jan. 2017. (HNHM 104157). Paratypes, same data (coll. Grego 1 specimen); type locality, leg. Angyal and Liévano.

Measurements.

Holotype: H 1.58 mm; W 1.56 mm; WB 1.08 mm; AH 0.90, AW 0.70 (holotype). Figs 11-13. Paratype: H 1.56 mm; W 1.30 mm; WB 1.06 mm; AH 0.84, AW 0.66 (holotype). Figs 14-16.

Etymology.

Named after renowned malacologist and good friend Fred Thompson from University of Florida, Gainesville, who contributed much to the knowledge of Cochliopidae of US and Mexico and compiled the first checklist of terrestrial and freshwater gastropods of Mexico and Central America ( Thompson 2008).

Description.

The milky whitish, translucent conical shell with 3 inflated convex whorls with a deep suture, blunt apex, and flat protoconch. The first teleoconch whorls rapidly expanding, forming a characteristic depressed, sometimes umbilicated appearance. The surface finely lirated, crossed by very fine axial ribs. The spiral lirated sculpture gradually coarsened towards the upper suture of the body whorl, on which the prominent carina-like spiral rib with fine regular conical spines. In some specimens only nodules or only faint knobs present (paratype 1). The body whorl broadened near the aperture. The aperture axially elongated and oval; the columellar peristome reflexed and characteristically sinuated. Umbilicus broad and open.

Habitat.

See Mexicenotica xochii sp. n.

Distribution.

Only known from the type locality. Within the type locality the new species was found together with the Mexicenotica xochii sp. n. and cf. Pisidium sp.