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lists have never been systematically revised from the colonial period to the present, so these classifications are outdated.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.
A new species of the megascolecid earthworm genus Pontodrilus Perrier, 1874, Pontodrilus longissimus sp. n., is described from seashores of Thailand and Peninsular Malaysia. The new species differs from congeners, especially the cosmopolitan P. litoralis (Grube, 1855) in the size of the body, number of segments and the shape of the spermathecae. P. litoralis is redescribed, based on specimens collected from the same region and the same type of habitat. DNA fragments of the mitochondrial cytochrome oxidase subunit I of both species were sequenced. Morphological as well as DNA sequence-based comparisons confirm that P. longissimus sp. n. is a lineage distinct from P. litoralis and in fact a new species. The illustrated descriptions are accompanied by a key to species of Pontodrilus.
The luminous earthworm Pontodriluslitoralis (Grube, 1855) occurs in a very wide range of subtropical and tropical coastal areas. Morphometrics on size variation (number of segments, body length and diameter) and genetic analysis using the mitochondrial cytochrome c oxidase subunit 1 (COI) gene sequence were conducted on 14 populations of P.litoralis from Southeast Asia and Japan. Statistical inference on morphometric data revealed significantly different size variations in the body length and diameter among these 14 populations of P.litoralis. However, discordance between the morphometric and mitochondrial COI gene-based phylogenetic analyses was evident, where the size variations in P.litoralis showed a different pattern from the COI genetic differences. The update on the current distribution of P.litoralis is reported and revealed different aspects of the littoral habitat characteristics between Southeast Asia and Japan.
Three new species of semi-aquatic freshwater earthworms of the genus Glyphidrilus Horst, 1889 are described from Malaysia.Glyphidrilus bisegmentus sp. n. was collected from Air Banun Pandig, Perak, Glyphidrilus kotatinggi sp. n. from Kota Tinggiwaterfall, Johor, and Glyphidrilus peninsularis sp. n. from Sungei Bantang, Johor. For comparison, type and non-type materialof five morphologically similar species was reinvestigated. The descriptions of the new species include illustrations of the external and internal morphological characteristics.
Specific status and species boundaries of several freshwater prawns in the Macrobrachium pilimanus species group remain ambiguous, despite the taxonomic re-description of type materials and additional specimens collected to expand the boundaries of some species. In this study, the “pilimanus” species group of Macrobrachium sensu Johnson (1958) was studied using specimens collected from montane streams of Thailand. Molecular phylogenetic analyses based on sequences of three molecular markers (COI, 16S and 18S rRNA) were performed. The phylogenetic results agreed with morphological identifications, and indicated the presence of at least nine putative taxa. Of these, six morphospecies were recognised as M. malayanum, M. forcipatum, M. dienbienphuense, M. hirsutimanus, M. eriocheirum, and M. sirindhorn. Furthermore, three morphologically and genetically distinct linages were detected, and are described herein as M. naiyanetri Siriwut sp. nov., M. palmopilosum Siriwut sp. nov. and M. puberimanus Siriwut sp. nov. The taxonomic comparison indicated wide morphological variation in several species and suggested additional diagnostic characters that are suitable for use in species diagnoses, such as the shape and orientation of fingers, the rostrum form, and the presence or absence of velvet pubescence hairs and tuberculated spinulation on each telopodite of the second pereiopods. The “pilimanus” species group was portrayed as non-monophyletic in both ML and BI analyses. The genetic structure of different geographical populations in Thailand was detected in some widespread species. The species delimitation based on the four delimitation methods (BIN, ABGD, PTP and GMYC) suggested high genetic diversity of the “pilimanus” species group and placed the candidate members much higher than in previous designations based on traditional morphology. This finding suggests that further investigation of morphological and genetic diversity of Southeast Asian freshwater prawns in the genus Macrobrachium is still required to provide a comprehensive species list to guide efforts in conservation and resource management.
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