Tricula lenahani, 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 : 21-23

Tricula lenahani sp. n. Figs 25-28

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 of cave river banks (Fig. 2B).

Type material.

Holotype: type locality: J. Grego and M. Olšavský leg. 11-12 February 2017 (NHMUK 201800010). Paratypes: type locality (NHMUK 20180021 - 5 specimens; HNHM 102774 - 5 specimens; OSUM 42391 - 5 specimens; coll. Grego F0879 - 103 specimens); Laos, Khammouane Province, Tham Nam Dôn Cave 17°33.82'N; 104°52.30'E, 161 m a.s.l., temporary side rivulet sediment at entrance passage 1.5 km from the main entrance, dry sand on the cave floor; J. Grego leg. 11 February 2017 (coll. Grego F0868 - 1 specimen); Laos, Khammouane Province, 3 km NW of Ban Na Village, sand on the bottom of Nam Dôn River source at 149 m a.s.l.; J. Grego leg. 07 February 2017. 17°33.20'N; 104°52.38'E (coll. Grego - 6 specimens) (Fig. 2A).

Measurements.

Holotype: H 2.72 mm; W 1.71 mm; BW 0.96 mm; BH 1.70 mm; AH 1.15 mm; AW 0.93 mm; H/W 1.59; AH/AW 1.24; W/BW 1.78; H/BH 1.60 H/AH 2.37; W/AW 1.84.

Diagnosis.

This species is similar to the syntopic Tricula valenasi sp. n., but differs from it by its more robust, shorter shell with a more open umbilicus as well as by its sinuated labral margin profile. It differs from syntopic T. spelaea sp. n. by its more inflated shell shape, and a different arrangement of the whorls, a larger umbilicus and a different shape of the aperture. It can be distinguished from syntopic T. davisi sp. n. by its more slender, less inflated shell and the shape of the columellar peristome. From T. bollingi Davis, 1968 it differs by its general shell shape and the position of the aperture, and by its more open umbilicus and blunter apex.

Description.

The whitish, semi-translucent shell has five convex whorls with a deep suture. The surface is smooth with fine, whitish, inconsistent axial bands. The shell is ovate-conical with whorls smoothly tapering towards the apex. The aperture is ear-shaped; the peristome expands outwards especially at the columellar side. The lateral edge of the labral lip is characteristically sinuated, as well a week sinuation is present at apical inner peristome. The umbilicus is open, partly obscured by the reflected columellar margin.

Etymology.

This species in named after my ever helpful friend Peter Lenahan, an avid caver from New York City, USA, for his great support during the field trip and for his indispensable help to Ban Na village by supporting construction of a new well and tap water supply for the villagers.

Distribution.

Only known from the type locality and nearby sites in Tham Khon Dôn Cave as well as in the related source of Nam Dôn River.

Ecology.

The same as Pseudoiglica pseudoiglica sp. n..