Search

Macrobrachium lanchesteri (De Man, 1911), a translucent freshwater prawn has a wide distribution range throughout mainland Southeast Asia. A high morphological variation and genetic divergence between different geographical M. lanchesteri populations in Thailand have peculiarly extended the uncertainty of species boundaries and blended confusingly with several Macrobrachium species. To clarify these circumstances, broad sample examinations of the morphological variation, including topotype specimens, and phylogenetic reconstruction based on the concatenated mitochondrial dataset (16s rRNA and COI genes) were performed. Broad morphological examination of M. lanchesteri has shown congruency with phylogenetic analyses by revealing prominent lineages of M. lanchesteri sensu stricto and two new sibling lineages with interspecific variation between 6.48–8.76% for COI and 3.06–4.23% for 16S. Descriptions of two new species, named herein as M. panhai Chaowvieng & Siriwut, sp. nov. and M. rostrolevatus Chaowvieng & Siriwut, sp. nov. are provided. Morphological investigation of rostral form suggested plasticity in M. rostrolevatus populations showing the morphological trait associated with their habitat preferences. Furthermore, phylogenetic positions of the three taxa affirmed the hidden diversity of Thai freshwater Macrobrachium fauna correlated with the river network in the Mekong and Chao Phraya basins, Thailand. The genetic data and distribution records obtained in this study may also assist future river conservation plans as well as the sustainable management of freshwater prawn diversity. [ABSTRACT FROM AUTHOR]

The speciose land snail genus Sarika is widely distributed throughout mainland Southeast Asia. This genus is generally recognized by a smooth and polished shell. However, we recognize four species with a ribbed shell surface (S. siamensis, S. theodori, S. costabilis sp. nov., and S. costata sp. nov.) exhibiting genital characters similar to those of Sarika s.s. and so a rearrangement in the systematics of the genus is suggested. Here, we analysed these four ribbed shell species together with Sarika s.s. by a combined morphological and molecular approach to species delineation, the latter based on both mitochondrial (coi and 16S) and nuclear (28S) markers. Our molecular phylogeny affirms the monophyly of the genus Sarika including both smooth and ribbed shell morphotypes that is statistically well supported. The ribbed shell morphotype in the land snail genus Sarika is also well defined in terms of diagnostic morphoanatomical characters that can be divided into two species groups. The S. costata species group consists of only one species, S. costata sp. nov., while the S. siamensis species group comprises S. siamensis, S. theodori and S. costabilis sp. nov. These findings provide a solid basis for the systematics of family Ariophantidae. [ABSTRACT FROM AUTHOR]

Material of the giant pill-millipede genus Zephronia Gray, 1832 recently collected from Thailand contains three new species: Zephronia enghoffi sp. nov., Zephronia golovatchi sp. nov., and Zephronia panhai sp. nov. The first Zephronia species recorded for Thailand, Z. siamensis Hirst, 1907, is also redescribed based on new specimens collected both from the type locality in Chonburi Province and from neighboring areas. Morphological characters of all new species, Z. phrain Likhitrakarn & Golovatch, 2021, and Z. siamensis are illustrated, and a distribution map of the confirmed Zephronia species occurring in Thailand is also provided. [ABSTRACT FROM AUTHOR]

The genus Hemiplecta is a group of large-sized land snails which have long been used as a food resource by Indochinese people. There are five dextral and four sinistral species currently recognized from Thailand. The dextral group is comprised of two previously recorded species (H. humphreysiana and H. distincta), two newly recorded species (H. funerea and H. esculenta), and one new species (H. nemorosa sp. nov.) from northern Thailand is being proposed. We reassessed the diagnostic characters of the genitalia, mantle edge, and radula. Specimens were classified into the genus Hemiplecta on the basis of the penial verge and shell lobe, and on the characters of a bulbous gametolytic sac without a gametolytic duct. A complete species list, together with photographs of the name-bearing types or authenticated specimens and the taxonomic status of Hemiplecta s.l. that are known from Indochina including Peninsular Malaysia and Myanmar, is provided for the first time. In total, this species list contains 39 available nominal species names described from this area. Type or authentic specimens can be located for 37 nominal species names, of which 25 are illustrated herein and the other 12 were recently illustrated. However, two available species-level names could not be traced to any type specimens. In addition, lectotypes of H. funerea and H. pluto are designated herein to stabilize the names. [ABSTRACT FROM AUTHOR]

The snorkel snail genus Rhiostoma Benson, 1860 is comprised of terrestrial cyclophorid snails with wideranging species diversity and radiation in Southeast Asia. The typical characters of the genus are a depressed shell, a detached and descending portion of the last whorl with a distinctive peristomal breathing device attached, and a calcareous cup-shaped operculum. Herein, we have revised the systematics of extant species based on shell morphology combined with COI barcoding. From these thirty recognised species, twelve are described as new to science: R. ? amarapuraense sp. nov., R. anceyi sp. nov., R. breviocollar sp. nov., R. ebenozostera sp. nov., R. cheliopegma sp. nov., R. furfurosum sp. nov., R. gnomus, sp. nov., R. lannaense sp. nov., R. laoense sp. nov., R. platymorpha sp. nov., R. rhothonotaphrosa sp. nov., and R. tigrina sp. nov. All conchological characters are provided via illustrations of type specimens and living snails, and descriptions of the shells and radulae. Phylogenetic analysis based on partial COI gene sequences strongly supports the designated morphospecies and a monophyletic Rhiostoma, confirming that all pterocyclinid snails with a calcareous, cup-shaped operculum belong to the same clade. A high intra-specific divergence was observed in R. jalorensis and R. housei populations from locations in close proximity, suggesting a lower dispersal and higher level of isolation. The low inter-specific divergence found in R. hainesi, R. samuiense, R. asiphon, and R. rhothonotaphrosa sp. nov. supports their recent diversification and local adaptation, and is congruent with their marked morphological differences. Finally, nine formerly Rhiostoma-placed species were reclassified into either the genus Cyclotus or the genus Opisthoporus. [ABSTRACT FROM AUTHOR]

The carnivorous terrestrial snail family Streptaxidae, recognized by having a regular to eccentric shell with complex apertural dentition, remains little-known and largely unexplored in Myanmar. This article presents historically recorded species and provides new data on this family. A total of eighteen species in five genera, namely Carinartemis, Discartemon, Haploptychius, Oophana, and Perrottetia from the southeastern and eastern parts of Myanmar, is examined herein. Among these, Haploptychius is the most diverse with eight species, while the remaining genera are comprised of fewer than five species each. Streptaxis birmanica and Streptaxis blanfordianus are herein synonymized with Haploptychius blanfordi, while Streptaxis hanleyanus is synonymized with Carinartemis sankeyi. Furthermore, the first genitalia and radula descriptions for three previously known species, D. tonywhitteni, C. exacutus, and C. sankeyi, are provided. Using comparative morphological and anatomical approaches, four new species are described: D. paurodeviatus sp. nov., H. heliakosus sp. nov., H. tenasserimicus sp. nov., and H. karenorum sp. nov. This present study enhances the understanding of the land snail fauna in Myanmar, specifically the streptaxids, and highlights that limestone areas are important for biodiversity conservation. [ABSTRACT FROM AUTHOR]

Four new species of terrestrial earthworms from the zebrus-group in the genus Amynthas Kinberg, 1867, are described from Nan province, north Thailand: A. phatubensis sp. n., from Tham Pha Tub Arboretum, A. tontong sp. n., from Tontong Waterfall, A. borealis sp. n., from Chaloemprakiat district, and A. srinan sp. n., from Srinan National Park. After comparing with the two closely related Laos species A. chandyi Hong, 2008 and A. namphouinensis Hong, 2008, the four new species show clear morphological diff erences, and also it is confirmed that there are no previous records of the species described here. Amynthas phatubensis sp. n. is the largest (longest) sized of these earthworms and is the only species that lives in limestone habitats. The genital characters are diff erent among them and also from the two Laotian species. Molecular systematics would be a good method for further analysis of the diversity and species boundaries in SE Asian Amynthas. [ABSTRACT FROM AUTHOR]