The land area of Laos is composed of a large variety of undisturbed habitats, such as high mountainous areas, huge limestone karsts and the lower Mekong Basin. Therefore, Laos is expected to have a high species diversity, especially for the land snails. However, with respect to research on malacology, Laos is probably the least well-researched area for land snail diversity in Indochina (including Laos) over the past few centuries. The handful of species lists have never been systematically revised from the colonial period to the present, so these classifications are outdated. Herein we present the first comprehensive annotated checklist with an up-to-date systematic framework of the land snail fauna in Laos based on both field investigations and literature surveys. This annotated checklist is collectively composed of 231 nominal species (62 ‘prosobranch’ and 169 heterobranches), of which 221 nominal species are illustrated. The type specimens of 143 species from several museum collections and/or 144 species of newly collected specimens are illustrated. There are 58 species recorded as new to the malacofauna of the country, and two new replacement names are proposed as Hemiplectalanxangnica Inkhavilay and Panha, nomen novum (Ariophantidae) and Chloritiskhammouanensis Inkhavilay and Panha, nomen novum (Camaenidae). Four recently described species of the genus Amphidromus from Laos, “thakhekensis”, “richgoldbergi”, “attapeuensis” and “phuonglinhae” are synonymized with previously described species. In addition, thirteen nominal species are listed as uncertain records that may or may not occur in Laos. This annotated checklist may inspire malacologists to carry on systematic research in this region.

Abstract. The land snail genus

The family Streptaxidae in Laos is revised. Twelve species are known, mainly from limestone areas, in the genera Discartemon Pfeiffer, 1856, Perrottetia Kobelt, 1905, Haploptychius Möllendorff, 1906, and Indoartemon Forcart, 1946. Three new species, Perrottetia unidentata sp. n. and Perrottetia megadentata sp. n. from northern and central Laos, and Indoartemon diodonta sp. n. from central Laos, are described. All eight species of these three genera previously recorded from Laos are revised and discussed based on examined material from Laos, Cambodia, Vietnam and Thailand. Type material was examined and lectotypes are designated. Details of genital anatomy and radulae are provided, including the first detailed genitalia and radula descriptions from Haploptychius. Two novelties in Streptaxidae, a vaginal caecum, and the occurrence of aphallic individuals, are reported from Haploptychius pellucens (Pfeiffer, 1863).

Two new species of Glyphiulus are described and illustrated from northern Laos. The epigean Glyphiulus subbedosae Likhitrakarn, Golovatch & Panha, sp. n. is the second member of the granulatus-group to be found in that country and it seems to be especially similar to G. bedosae Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2007. However, it differs from the latter species by a row of several strong setae near the median marginal ridge on the paraprocts, combined with the gnathochilarium being considerably less densely setose on the caudal face, and the anterior gonopods showing a pair of smaller, apical, but larger lateral teeth on the coxosternal plate. Glyphiulus semicostulifer Likhitrakarn, Golovatch & Panha, sp. n. is the fourth member of the javanicus-group to be discovered in Laos, taken from a cave. It seems to be particularly similar to G. costulifer Golovatch, Geoffroy, Mauriès & VandenSpiegel, 2007, but is distinguished by the more sparsely alveolate background fine structure of the metazonae, coupled with the gnathochilarium being considerably less densely setose on the caudal face, much stronger paramedian prongs and 4-segmented telopodites on ♂ coxae 1, the slightly longer and more slender apicoparamedian sternal projections on the anterior gonopods, and the much longer flagella of the posterior gonopods. An identification key to and a distribution map of Glyphiulus species in Laos are also presented.

Nine new species of Amynthas (Clitellata: Megascolecidae) from Mt. Phouleoi, Lao PDR: Earthworm specimens were collected on the top of Mt. Phouleoi, Viengthong District, Houaphanh province, Lao PDR. The new species belonged to pheretimoid earthworms. They have spermathecal pores in 7/8 and 8/9, corresponding to the aeruginosus-group as characterized by Sims and Easton (1972). Their names are: Amynthas bouatongi sp. nov., Amynthas hoauykanangensis sp. nov., Amynthas phimpheti sp. nov., Amynthas nametensis sp. nov., Amynthas somechanae sp. nov., Amynthas wiggeri sp. nov., Amynthas fleischmani sp. nov., Amynthas antethecus sp. nov., and Amynthas elenabondae sp. nov. With the exception of A. nametensis sp. nov., all have the first dorsal pore in an unusually anterior location close to 5/6 and very large, often coiled, prostatic ducts. Several species have slight intraparietal invaginations of the primary male pores, but the similarity of other characters leads us to include them in Amynthas rather than in a polyphyletic Metaphire. Amynthas bouatongi sp. nov. has male pores 0.20–0.24 circumference apart on reniform male pads, pair genital papillae medial and lateral to male pores in XVIII. Amynthas hoauykanangensis sp. nov. has openings of copulatory pouches 0.19–0.25 circumference apart, and paired round genital papillae on postsetal XVII and presetal XIX in line with the male pores. Amynthas phimpheti sp. nov. has male pores 0.21–0.24 circumference apart, round thickened genital papillae paired on 17/18 and 18/19 in line with male pores. Amynthas nametensis sp. nov. has male pores superficial on thickened circular pads, 0.24–0.27 circumference apart. Amynthas somechanae sp. nov. has male pores 0.20–0.33 circumference apart, and paired equatorial papillae in XVIII. Amynthas wiggeri sp. nov. has male pores 0.22–0.30 circumference apart, paired genital papillae equatorial on XVIII medial to male pores and paired papillae equatorial in XVII and XIX. Amynthas fleischmani sp. nov. has openings of copulatory pouches 0.24 circumference apart, paired conical genital papillae equatorial on XVII and XIX; paired circular papillae in intersegmental furrows of 17/18 and 18/19. Amynthas antethecus sp. nov. has openings of copulatory pouches 0.31 circumference apart, paired circular papillae in intersegmental furrow of 17/18 and equatorial on XIX, slightly medial to secondary male pores. Amynthas elenabondae sp. nov. has openings of copulatory pouches 0.19 circumference apart, crescent, convex medially; primary male pore on tubercle on lateral wall of shallow parietal invagination.

Land snail surveys conducted in northern Laos between 2013 and 2014 have led to the discovery of a living population of Trichelix horrida (Pfeiffer, 1863). This species has never been recorded from specimens other than the types, and its distribution and anatomy have remained essentially unknown. The genitalia and radula morphology are documented here for the first time and employed to re-assess the systematic position of this species: the unique morphological characters of T. horrida are a penis similar in length to the vagina, a small and triangular penial verge, gametolytic organs extending as far as the albumen gland, head wart present, and unicuspid triangular radula teeth. The type locality of this species was believed to be from “Lao Mountains, Camboja,” and is restricted herein to be Luang Phrabang Province, northern Laos. The assignment of species to either of three genera, Trichelix Ancey, 1887, Moellendorffia Ancey, 1887, and Moellendorffiella Pilsbry, 1905, based solely on information provided in their original descriptions is difficult. The type specimens of all nominal species presently placed in either of these three genera are examined and illustrated herein. Comparison with the primary type specimens will assist future revisions aiming to resolve the systematics of these taxa. In addition, we transfer Moellendorffia faberiana (Möllendorff, 1888) to the genus Moellendorffiella.

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This project also fostered local technical development as it supported research and analysis by the universities and researchers of the University Network for Wetland Research and Training in the Mekong Region. Not only did this work support greater scientific understanding of the critical challenge posed by POPs contamination, it advanced the development of greater local capability and transboundary cooperation in the field of wetland ecology in the Mekong Basin.