Tricula valenasi, Grego, Jozef, 2018

Grego, Jozef, 2018, First record of subterranean rissoidean gastropod assemblages in Southeast Asia (Mollusca, Gastropoda, Pomatiopsidae), Subterranean Biology 25, pp. 9-34 : 20-21

Tricula valenasi sp. n. Figs 23-24

Type locality.

Laos; Khammouane Province, Ban Na village 20 km NNE of Thakhek, Tham Khon Dôn Cave 17°33.82'N; 104°52.30'E, 161 m a.s.l., Earthquake Dome 3 km from the south entrance, sand sediments at cave river banks (Fig. 2B).

Type material.

Holotype: type locality: J. Grego and M. Olšavský leg. 11-12 February 2017 (NHMUK 20180008). Paratypes: type locality (coll. Grego F0877 - 3 specimens).

Measurements.

Holotype: H 3.25 mm; W 1.65 mm; BW 1.05 mm; BH 1.25 mm; AH 1.15 mm; AW 0.95 mm; H/W 1.97; AH/AW 1.2; W/BW 1.57; H/BH 2.60; H/AH 2.83; W/AW 1.74.

Diagnosis.

Tricula valenasi sp. n. is similar to syntopic T. lenahani sp. n., from which it differs by its elongate shell with a less open umbilicus and an aperture more prominent at the shell periphery outline. It differs significantly from syntopic T. davisi sp. n. by its longer, more elongated shell shape, its more inflated whorls and its proportionally smaller aperture with a straight columellar margin rather than the columellar sinuation characteristic of T. davisi sp. n. From T. bollingi Davis, 1968 it differs by the aperture shape, which extends beyond the shell periphery outline and by its more open umbilicus and more blunt apex. It can be distinguished from T. burchi Davis, 1968, by its more slender and more conical shape with a smaller aperture, a more prominent umbilicus and a less blunt apex.

Description.

The whitish shell has five rounded convex whorls with a semi-deep suture and a blunt apex. The surface is smooth and shiny. The shell is narrow-conical with prominent body whorl. Umbilicus is tiny opened. In frontal view, the outer part of the aperture protrudes from the shell periphery outline. Aperture is ovoid ear-shaped, separated from the body whorl by a very weak furrow and an adapical gap. The peristome margin is blunt, slightly reflexed outwards. The outer lip is slightly callous and has a straight lateral profile.

Etymology.

Named after my friend Liviu Valenas (Nuremberg, Germany), an avid speleologist born in Romania, who spent 10 years exploring the cave system Pha Soung, which, with its currently documented 20.4 km, is the third largest cave system in Laos.

Distribution.

Only known from the type locality.

Ecology.

The same as Pseudoiglica pseudoiglica sp. n.