First record of subterranean rissoidean gastropod assemblages in Southeast Asia (Mollusca, Gastropoda, Pomatiopsidae) Author Grego, Jozef text Subterranean Biology 2018 25 9 34 http://dx.doi.org/10.3897/subtbiol.25.23563 journal article http://dx.doi.org/10.3897/subtbiol.25.23563 1314-2615-25-9 9F789679CD744D54A7F2B0087E154571 Tricula spelaea sp. n. Figs 33-36 Type locality. Laos; Khammouane Province, Ban Na village 20 km NNE of Thakhek, Tham Khon Don 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 bank (Fig. 2B). Type material. Holotype: type locality: J. Grego and M. Olsavsky leg. 11-12 February 2017 (NHMUK 20180011). Paratypes: type locality (Grego F0880 - 3 specimens); Laos, Khammouane Province, Ban Na village 20 km NNE of Thakhek, Tham Pha Soung Cave, 17°33.052'N ; 104°52.410'E , 155 m a.s.l., sandy sediment on the bottom of Frog Lake at central part of the cave (coll. Grego F0886 - 2 specimens). Measurements. Holotype: H 2.80 mm; W 1.65 mm; BW 1.05 mm; BH 1.80 mm; AH 1.10 mm; AW 0.95 mm; H/W 1.70; AH/AW 1.16; W/BW 1.57; H/BH 1.56; H/AH 2.55; W/AW 1.74. Diagnosis. This new species is similar to syntopic Tricula lenahani sp. n., from which it differs by its more conical shell with less inflated whorls, a closed umbilicus and the different shape of the aperture. It differs significantly from syntopic T. valenasi sp. n. by its shorter, more inflated shell shape, more flattened whorls, straight lateral labral profile and closed umbilicus. From the T. bollingi Davis, 1968 it differs by its shell and aperture shape, position of the aperture and a more blunt apex. From T. burchi Davis, 1968, it differs by its more conical shape with a smaller aperture. The labral lateral profile of T. spelaea sp. n. is straight, and no sinuation is present on its columellar side. Description. The shell shape is conical with five somewhat flattened but still convex whorls with a weak suture and blunt apex. The surface is milky whitish and smooth. The aperture is oval tear-shaped; the peristome slightly callous expanding outwards. The labral lip lateral profile is straight, and no sinuation is present at the apical inner lip. The umbilicus is closed. Etymology. Named after its type locality inside the Cave Tham Khon Don in Khammouane. Distribution . Only known from the type locality and nearby sites in Tham Khon Don Cave as well from the related source of Nam Don River. Ecology. The same as Pseudoiglica pseudoiglica sp. n.