Contributions of a small collection of terrestrial microsnails (Pupilloidea, Hypselostomatidae) from Myanmar with description of three new species.

Land snails were collected for the project 'Conserving Myanmar's Karst Biodiversity' from the limestone karsts in Mon, Kayin, and Shan states and in the regions of Tanintharyi and Mandalay between 2015 and 2017, through cooperation with Fauna and Flora International (FFI) and the Forestry Department of Myanmar. Here, we report on a portion of the collection, and list 17 species from seven genera of the Hypselostomatidae microsnails. Three new species from two genera are described as Bensonellataiyaiorum Tongkerd & Panha, sp. nov., B.lophiodera Tongkerd & Panha, sp. nov., and Gyliotrachelaaunglini Tongkerd & Panha, sp. nov. All new species are known only from the type locality in Shan State (Bensonella) and Kayin State (Gyliotrachela). A new combination of Acinolaemusdayanum and three newly recorded species, namely A.cryptidentatus, B.anguloobtusa and G.hungerfordiana are discussed. The low morphological variability of the widely distributed G.hungerfordiana is discussed, and two species are proposed for formal synonymisation. Constituting the first records for Myanmar, five species of Bensonella and two species of Acinolaemus were collected.

Systematic revision of the snorkel snail genus Rhiostoma Benson, 1860 (Gastropoda, Caenogastropoda, Cyclophoridae) with descriptions of new species.

The snorkel snail genus Rhiostoma Benson, 1860 is comprised of terrestrial cyclophorid snails with wide-ranging 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. ? amarapuraensesp. nov., R.anceyisp. nov., R.breviocollarsp. nov., R.ebenozosterasp. nov., R.cheliopegmasp. nov., R.furfurosumsp. nov., R.gnomus, sp. nov., R.lannaensesp. nov., R.laoensesp. nov., R.platymorphasp. nov., R.rhothonotaphrosasp. nov., and R.tigrinasp. 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.rhothonotaphrosasp. 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.

Phylogeny and biogeography of Indochinese freshwater mussels in the genus Pilsbryoconcha Simpson, 1900 (Bivalvia: Unionidae) with descriptions of four new species.

The body of knowledge regarding the classification and evolution of freshwater mussels in the family Unionidae (Bivalvia) in Indochina has recently increased. However, the taxonomic revision of all extant taxa in the region is still ongoing. In this study, the genus Pilsbryoconcha was revised based on an integrative analysis of shell morphology, biogeography, and molecular data. Multi-locus phylogeny indicated the availability of eight species within the genus. Four previously recognized species are P. exilis (Lea, 1838), P. schomburgki (Martens, 1860) stat. rev., P. linguaeformis (Morelet, 1875), and P. carinifera (Conrad, 1837), while four other species are described herein as P. acuta sp. nov., P. mekongiana sp. nov., P. kittitati sp. nov., and P. hoikaab sp. nov. In addition, the neotype of P. carinifera is also designated to clarify its long taxonomic ambiguity. Divergent time estimation and historical biogeography analysis revealed that Pilsbryoconcha originated in the area now called the Khorat Plateau around the middle of the Eocene (mean age = 43.12 Mya), before its range was expanded across Indochina through a series of complex geomorphological changes of river systems, which also led to diversification of the genus.

Untangling a mess of worms: Species delimitations reveal morphological crypsis and variability in Southeast Asian semi-aquatic earthworms (Almidae, Glyphidrilus).

Semi-aquatic freshwater earthworms in the genus Glyphidrilus from Southeast Asia are characterized by both an extreme morphological crypsis among divergent phylogenetic lineages and a high morphological variability within the same phylogenetic lineages. The present study provides a new taxonomic framework for this problematic genus in SE Asia by integrating DNA sequence and morphological data. When single-locus and multilocus multispecies coalescent-based (MSC) species delimitation methods were applied to DNA sequence data, they usually yielded highly incongruent results compared to morphology-based species identifications. This suggested the presence of several cryptic species and high levels of intraspecific morphological variation. Applying reciprocal monophyly to the cytochrome c oxidase subunit 1 (COI) gene tree allowed us to propose the existence of 33 monophyletic species. Yet, often substantially more molecular operational taxonomic units (MOTUs) were obtained when species delimitation was based on COI and 16S rRNA sequences. In contrast, the ITS1 and ITS2 sequences suggested fewer MOTUs and did not recover most of the monophyletic species from the Mekong basin. However, several of these latter taxa were better supported when MSC species delimitation methods were applied to the combined mtDNA and ITS datasets. The ITS2 secondary structure retrieved one unnamed Mekong basin species that was not uncovered by the other methods when applied to ITS2 sequences. In conclusion, based on an integrative taxonomic workflow, 26 Glyphidrilus candidate species were retained and two remained to be confirmed. As such, this study provides evidence to suggest nine species new to science and to synonymize 12 nominal morphospecies. It also illustrates that the uncritical use of COI as a universal DNA barcode may overestimate species diversity because COI may be unable to distinguish between divergent conspecific lineages and different candidate species.

Two new Cambodian semi-aquatic earthworms in the genus Glyphidrilus Horst, 1889 (Oligochaeta, Almidae), based on morphological and molecular data.

Combining morphological and molecular data is a powerful approach to support the discovery of new species. Here, two new species of the semi-aquatic earthworm genus Glyphidrilus, G. jamiesoni sp. n. and G. kralanhensis sp. n., are described from the Mekong Basin in Cambodia. They are morphologically distinguished by the respective locations of wings and spermathecae; furthermore, G. kralanhensis sp. n. has three pairs of ovaries, probably an autapomorphic trait. In addition, two mitochondrial gene fragments (COI and 16s rRNA) were sequenced of types of the new species and of five further Glyphidrilus species described recently from the Mekong basin in Thailand and Laos. They revealed a high level of genetic divergence of the new species compared to the other earthworm taxa. The evolutionary relationships among the Mekong Glyphidrilus members is discussed with reference to the recent paleogeography of the Mekong River drainage.

Allozyme variation in the camaenid tree snails Amphidromus atricallosus (Gould, 1843) and A. inversus (Müller, 1774).

We examined allozyme variation in two camaenid tree snails, Amphidromus atricallosus and A. inversus, across two principal regions of Thailand and from Singapore, plus for A. inversus, one site in peninsular Malaysia. Using horizontal starch gel electrophoresis, 13 allozyme loci (11 polymorphic) were screened for A. atricallosus and 18 (5 polymorphic) for A. inversus. Heterozygosity was higher in A. atricallosus (Hexp=0.018-0.201, mean=0.085) than in A. inversus (Hexp=0-0.023, mean= 0.002). Genetic heterogeneity among samples was higher in A. inversus (Fst=0.965) than in A. atricallosus (Fst=0.781). Within A. atricallosus, populations were more differentiated in southern Thailand (Fst=0.551) than in eastern Thailand (Fst=0.144). The high Fst and low Hexp in populations of A. inversus suggest that this species is likely to have experienced a series of strong bottlenecks, perhaps occurring chiefly on offshore continental-shelf islands. The low Fst values of A. atricallosus in eastern Thailand suggest frequent gene flows among populations in this region. The southern and eastern samples of A. atricallosus exhibited fixed allele differences at four loci and great genetic distance (Nei's D=0.485-0.946), suggesting that these two samples may actually represent, or else be evolving into, separate species.