Thamkhondonia moureti, 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 : 16-17

Thamkhondonia moureti sp. n. Figs 13-14

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 on cave river banks (Fig. 2B).

Type material.

Holotype: type locality: J. Grego and M. Olšavský leg. 11-12 February 2017 (NHMUK 20180005). Paratypes: type locality (NHMUK 20180018 - 2 specimens; HNHM 102771 - 2 specimens; OSUM 42384 - 2 specimens; coll. Grego F0874 - 33 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 F0865 - 2specimens); 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 F0855 - 1 specimen) (Fig. 2A).

Measurements.

Holotype: H 4.48 mm; W 1.42 mm; BW 0.80 mm; BH 1.55 mm; AH 1.01 mm; AW 0.91 mm; H/W 3.15; AH/AW 1.11; W/BW 1.78 H/BH 2.89; H/AH 4.44; W/AW 1.56.

Diagnosis.

Compared to the most closely related syntopic species, Thamkhondonia vacquiei sp. n. and T. smidai sp. n., T. moureti sp. n. has a much higher and more slender shell with much coarser spiral sculpture and a proportionally smaller aperture.

Description.

The milky whitish, elongated turritiform shell has nine slightly convex whorls with a weak suture. The surface sculpture consists of 4-5 coarse spiral cords crossed by very fine axial ribs. The aperture is oval ear-shaped and extends beyond the shell periphery outline; the peristome is sharp and expands only at its columellar side. The lateral profile of the labral lip is straight and a characteristic axial varix is parallel to the labral lip. The umbilicus is closed.

Etymology.

Named after my friend, a renowned French geologist and speleologist Claude Mouret (Magnac-Bourg, France), who in 2006 discovered and for the first time explored the Tham Khon Dôn cave system, the largest cave in Laos, and led annual expeditions to explore caves of Khammouane. Without his substantial help, the sampling of the type locality in cave Tham Khon Dôn would not have been possible.

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.