Search

Two new genera and three new species of freshwater mussels in the tribe Pseudodontini (Bivalvia, Unionidae) are described from the Mekong Basin in Thailand based on an integrative taxonomic study involving morphology and multi-locus phylogenetic analyses (mitochondrial COI and 16S, and nuclear 28S genes). The monotypic genus, Lannanaia kokensis gen. et sp. nov., presents unique features of being rather compressed, sub-trigonal in outline with short and high shell, and with a distinct posterior wing. Another new genus, Isannaia gen. nov., is characterized by having a thin and moderately inflated shell, with rhomboidal to ovate outline. It includes two lineages that are genetically separated by 3.54% uncorrected COI p-distance, and are herein described as I. fortunata sp. nov. and I. occultata sp. nov. Phylogenetic analyses further revealed that these two new genera were nested within a clade of subtribe Pseudodontina, and with pairwise uncorrected COI p-distance to other genera ranging from 11.42 to 15.66%. Based on the present data, Lannanaia gen. nov. is known only from the Kok River in the north of Thailand, whereas the two species of Isannaia gen. nov. are restricted to tributaries of the Mekong River in the northeast of Thailand. The discovery of rare and probably endemic freshwater mussels in the Mekong Basin thus again highlights the importance of this region among freshwater biodiversity hotspots of the world.

The taxonomy of the pill millipede genus Rhopalomeris Verhoeff, 1906, which is restricted to Indochina and currently comprises six described species, is refined and updated. An integrative taxonomic approach was employed that combines morphological examination with DNA barcoding using the cytochrome c oxidase subunit I (COI) gene for species identification and delineation. The first objective was to confirm the identity of Rhopalomeris carnifex (Pocock, 1889), a charismatic species known as the “candy pill millipede” due to its vivid coloration, based on specimens collected near the type locality in Myanmar. The second objective was to describe a new species, Rhopalomeris nigroflava Likhitrakarn, sp. nov., discovered in Linno Gu, Kayin State, Myanmar. This new species is distinguished by its small body size (5.1–9.7 mm long) and yellow body with contrasting brown to blackish markings on certain terga. In addition, the position of the telopod syncoxital lobe relative to the lateral syncoxite horns separates it from other Rhopalomeris species. The interspecific divergence between R. nigroflava Likhitrakarn, sp. nov. and other congeners ranges from 10.85% to 16.13%, based on uncorrected COI p-distances, while the intraspecific divergence was 0%–7.44%. A distribution map of and a revised identification key to all known species of Rhopalomeris are also provided.

The poorly studied leatherleaf slug genus Valiguna in Thailand was carefully investigated. Members of this genus are phenotypically similar, making their identification very challenging. This study clarifies the taxonomic status of all Valiguna species in Thailand by combining morphological and anatomical studies with DNA barcoding. Monophyly of all Valiguna species was confirmed by analysis of the mitochondrial COI data and that all Valiguna species have the acropleurocaulis type of penis. Currently, three Valiguna species are recognised: V. siamensis, V. semicerina Mitchueachart & Panha, sp. nov., and V. crispa Mitchueachart & Panha, sp. nov. that are new to science. For distinct characteristics, V. siamensis is characterised by having a cylindrical penis and honeycomb-like glans, V. semicerina sp. nov. has a lanceolate penis with half honeycomb-like glans, and V. crispa sp. nov. has a cylindrical penis with wavy-like glans. In addition, more detailed descriptions of the radula and genitalia of all three species and their distribution are also carefully presented, enhancing the understanding of this leatherleaf slug genus in Thailand.

A large amount of material of the millipede genus Zephronia Gray, 1832 was collected during 2014–2023 from many parts of eastern Thailand. An integrative study of morphological characters and genetic data (COI gene) revealed two new species: Z. chantaburiensis Srisonchai & Wesener, sp. nov. and Z. macula Srisonchai & Wesener, sp. nov. The two new species clearly differ from other congeners by their unique characteristics, especially in their colour pattern and telopod shape. The interspecific genetic distances of the 658 bp COI gene barcoding fragment between these new species and all other species of giant pill-millipede from Thailand, Laos and Cambodia are 12.01–23.49% for Z. chantaburiensis sp. nov. and 17.93–25.13% for Z. macula sp. nov. While relationships among species remain preliminary, the phylogenetic tree shows that species of Zephronia are interspersed with species of Sphaerobelum Verhoeff, 1924 and Prionobelum Verhoeff, 1924. Phylogenetic analyses place both new species in a clade termed Zephronia s.s., which receives support also from morphological data, showing a unique position of the organ of Tömösváry. Z. macula sp. nov. appears to occur over a broad distribution whereas Z. chantaburiensis sp. nov. was found only at the type locality. Given that all known records are in the eastern part of Thailand, we thus regard both species as endemic. Morphological illustrations based on SEM micrographs and a distribution map are also provided.

The Malay Peninsula has traditionally been considered to harbour a diverse land-snail fauna, both in terms of a high species richness and a wide variety of conchological traits, especially within the limacoid land snails. A recent survey along the Malay Peninsula of southern Thailand discovered an overlooked limacoid taxon “Trochomorpha” sculpticarina Martens, 1883, previously assigned to genus Trochomorpha of the Trochomorphidae. This genus is herein described as Janbinmorpha gen. nov. based on comparative studies of shell morphology, external features, genital anatomy and radular morphology, as well as analyses of partial sequences of two mitochondrial markers, COI and 16S rRNA, and of one nuclear marker, 28S rRNA. This new genus is characterised by a combination of distinct morphological and anatomical features. The most distinguishing features are a depressed trochiform shell with a keeled last whorl, gametolytic organ without a duct, gametolytic sac with two lobes, and proximal epiphallus encircled with a thick sheath and attached by the penial retractor muscle. In addition, an analysis of the differentiation in mitochondrial and nuclear markers confirmed that this new genus, first recognised by morphology, is also genetically distinct. The molecular data also confirm that J. sculpticarina comb. nov. is a member of the Ariophantidae and has a close evolutionary relationship to Hemiplecta and Maelamaodiscus.

The taxonomy of subulinid snails in Myanmar has been evaluated, resulting in the recognition of 40 species and subspecies across nine genera: Allopeas, Bacillum, Curvella, Glessula, Opeas, Paropeas, Rishetia, Tortaxis, and Zootecus. Nine species are re-described based on recently collected specimens, and two new species, Glessula mandalayensis Man & Panha, sp. nov. from Mandalay Region and Tortaxis cylindropsis Man & Panha, sp. nov. from Shan State are introduced. The genitalia and radula of Zootecus pullus was studied for the first time. This study also presents a comprehensive list of all subulinid species recorded to date from Myanmar. The type specimens and authenticated museum specimens have been illustrated with accompanying taxonomic remarks and nine species formerly assigned in Glessula are now placed in Rishetia: R. akouktoungensis, R. baculina, R. basseinensis, R. burrailensis maxwelli, R. kentungensis, R. limborgi, R. nathiana, R. pertenuis, and R. pertenuis major.

Based on several field investigations, many molluscan shells and chondrichthyan teeth, together with other invertebrate and actinopterygian remains were found from the marine Bangkok Clay deposits in Ongkharak, Nakhon Nayok, at a depth of ~ 5–7 m below the topsoil surface. Animal macrofossils recovered from these Holocene marine deposits were identified and their chronological context was investigated in order to reconstruct the paleoenvironments of the area at that time. The majority of marine fossils recovered from the site consist of molluscs, with a total of 63 species identified. Other invertebrate species include a stony coral, a mud lobster, barnacles, and a sea urchin. The vertebrates are represented by fish remains, including carcharhinid shark teeth from at least nine species, stingray and trichiurid teeth, and one sciaenid otolith. The molluscan fauna indicates that the paleoenvironments of the area corresponded to intertidal to sublittoral zones, where some areas were mangrove forests and intertidal mudflats. The fish fauna is dominated by the river shark Glyphis, indicating freshwater influences and possibly occasional brackish conditions. The carbon-14 analysis of mollusc and charcoal remains shows that deposition of the marine sediment sequence began during the mid-Holocene, spanning approximately from 8,800 to 5,300 cal yr BP. This study provides in-depth insights into the diversity of fishes, marine molluscs, and other invertebrates from the Bangkok Clay deposits, supporting the existence of a marine transgression onto the Lower Central Plain of Thailand during the mid-Holocene.

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 Bensonella taiyaiorum Tongkerd & Panha, sp. nov., B. lophiodera Tongkerd & Panha, sp. nov., and Gyliotrachela aunglini 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 Acinolaemus dayanum 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.

This paper reassesses the taxonomy and systematics of 11 arboreal snail species in the genus Amphidromus from Vietnam, Cambodia, Indonesia and Laos (A. bozhii Wang, 2019, A. buelowi Fruhstorfer, 1905, A. costifer Smith, 1893, A. haematostoma Möllendorff, 1898, A. ingens Möllendorff, 1900, A. madelineae Thach, 2020, A. metabletus Möllendorff, 1900, A. pankowskianus Thach, 2020, A. placostylus Möllendorff, 1900, A. roseolabiatus Fulton, 1896, and A. thachi Huber, 2015). The taxonomic validity of each species is supported by a phylogenetic analysis of mitochondrial COI and 16S rRNA gene fragments from 17 ingroup taxa. Amphidromus buelowi was found to comprise two populations from two distant localities, one from Mount Singgalang, West Sumatra, Indonesia and the other from southern Vietnam. The samples from southern Vietnam were previously described as A. asper Haas, 1934 and A. franzhuberi Thach, 2016, but they are now treated as junior synonyms of A. buelowi in this study. In addition, two species from Vietnam are described as new to science, viz. A. asperoides Jirapatrasilp & Lee, sp. nov. and A. ingensoides Jirapatrasilp & Lee, sp. nov., each of which is conchologically comparable to A. buelowi and A. ingens, respectively.

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.

The status of the indigenous Southeast Asian apple snails belonging to the genus Pila is of concern due to their fast rate of population decline, possibly as a result of multiple factors including habitat loss or disturbance and the introduction of globally-invasive apple snails, Pomacea spp. Conservation actions, including captive breeding of the native Pila species, have been suggested as urgent remedial practices, but the lack of knowledge regarding the fundamental reproductive biology of indigenous Pila spp. makes such practices difficult. In the present study, observations on the mating and egg-laying behaviour of an economic valuable apple snail native to Southeast Asia, P. virescens, were conducted using video recording to examine and describe their reproductive behaviour under a laboratory condition. A total of 15 types of mating and seven egg-laying behaviour were recorded. The mating sequence which subsequently resulted in egg laying was comprised of seven types of major sequential behaviour: mate probing, mounting, shell circling, positioning, insemination posture, sheath withdrawal and dismounting. Rejection of mating attempts by the female was frequently observed. Egg laying occurred during either day or night. A sequence of seven distinct types of behaviour were performed during oviposition: climbing, positioning, forming a temporary tube, mucous secreting, egg depositing, leaving and resting. Overall, these results provide an understanding of the egg-laying behavioural process and highlight its complexity in P. virescens. In addition, detailed ethograms of mating and egg-laying behaviour were derived. These will promote further systematic comparative studies of the reproductive behaviour of apple snails.

A new species of the giant pill millipede genus Sphaerobelum is described: Sphaerobelum turcosa sp. nov. from the northeastern part of Thailand. Species delimitation is based on morphological characters and COI sequence data. The new species can be clearly discriminated from congeners by its greenish-blue body color, the face mask-like appearance of the thoracic and anal shields jointly when rolled up, and the combination of the following four characters: (1) the coxa of the second leg laterally with a sharp and long process, (2) the tarsi of legs 4–21 with 6–7 ventral spines, (3) the anterior telopods consisting of four conspicuous telopoditomeres, and (4) the immovable, slender (not strongly humped) and distally curved finger of the posterior telopods without a membranous spot. The interspecific COI sequence divergence between the new species and other Sphaerobelum species ranges from 17% to 23% (mean 20%). The intergeneric COI sequence divergence between the new species and Zephronia species ranges from 18% to 21% (mean 20%). The relationships among Sphaerobelum and Zephronia species based on the COI sequence data were not resolved in this study. Sphaerobelum turcosa sp. nov. is restricted to limestone habitat in Loei province and is probably endemic for the Thai fauna.

Abstract The mysterious world of the bioluminescent molluscs in terrestrial ecosystems is mesmerizing, but Quantula striata was previously the only terrestrial mollusc known to be luminescent. Here, we document the new discovery of bioluminescence in four land snails, namely Phuphania crossei, P. globosa, P. carinata, and P. costata. Our observations establish clearly that these four species of Phuphania produce a continuous greenish light from the light-emitting cells located within the mantle and the foot, and that its bright luminescence is intracellular and is not due to any luminous secretion. Although both Quantula and Phuphania can produce a green light, the luminescence patterns are different. The luminescence displayed by Quantula is rhythmical blinking or flashing, while Phuphania glows continuously. In addition, the bioluminescence in Q. weinkauffiana is confirmed, which is similar to that in the related species, Q. striata.

This study presents a complete species list of the door snails inhabiting Myanmar, updated to now include 33 taxa, and provides taxonomic notes together with a re-description of the shell, radula, and genitalia for 13 species and subspecies, including Oospira philippiana, the type species of the genus Oospira. The snails previously treated as subspecies or synonyms of Oospira gracilior and Oospira magna are reclassified and recognized as distinct species. The lectotype of Oospira insignis has been clarified and an illustration of the original type specimen provided. A long-overlooked species, Oospira andersoniana, has been collected and redescribed herein. Two new species from the limestone karsts in the Salween River Basin are introduced: Oospira luneainopsis Man & Panha, sp. nov. and Oospira zediopsis Man & Panha, sp. nov. A synoptic view of all clausiliid taxa known from Myanmar is presented along with taxonomic information and distributional records. Photographs of the type materials for all taxa are provided for further comparison or, if unavailable, photographs of the examined specimens or the original figure from the literature.

The pill millipede genus Hyperglomeris Silvestri, 1917 is reported from Laos for the first time. Two new species, namely H. bicaudata Likhitrakarn, sp. nov. and H. inkhavilayi Likhitrakarn, sp. nov., from Houaphanh and Khammouane provinces, northern Laos, are described and illustrated based on morphological characters and molecular analyses. Sequences of COI gene were used as DNA barcoding markers, and successfully supported the accurate identification of other Glomeridae species. Interspecific divergence of the COI uncorrected p-distance between these new species and other Hyperglomeris species ranged from 7.84–13.07%, while the intraspecific divergence was 0.45% in H. inkhavilayi sp. nov. and 5.3% in H. bicaudata sp. nov. The updated status of Hyperglomeris, a map of its distribution, and identification keys for all species are given.

The Southeast Asian genus Angustopila, currently comprising 13 nominal species, encompasses the world’s tiniest land snails. This work shows that there are far more species than previously suspected, and that this genus is in fact, a very speciose group of tiny snails widely distributed in Southeast Asia. Angustopila is revised based on type material of known species as well as 211 samples newly collected in China, Laos, Myanmar, Thailand and Vietnam. Altogether, 53 species and one subspecies are recognised, of which 42 species and subspecies are new to science: A. akrodon Páll-Gergely & Hunyadi, sp. nov., A. apiaria Páll-Gergely & Hunyadi, sp. nov., A. apiostoma Páll-Gergely & Vermeulen, sp. nov., A. apokritodon Páll-Gergely & Hunyadi, sp. nov., A. antidomedon Páll-Gergely & Hunyadi, sp. nov., A. babel Páll-Gergely & Vermeulen, sp. nov., A. bathyodon Páll-Gergely & Hunyadi, sp. nov., A. bidentata Páll-Gergely & Jochum, sp. nov., A. cavicola Páll-Gergely & Dumrongrojwattana, sp. nov., A. cicatricosa Páll-Gergely & Vermeulen, sp. nov., A. coprologos uninodus Páll-Gergely & Grego, ssp. nov., A. erawanica Páll-Gergely & Dumrongrojwattana, sp. nov., A. fratermajor Páll-Gergely & Vermeulen, sp. nov., A. fraterminor Páll-Gergely & Vermeulen, sp. nov., A. gracilis Páll-Gergely & Hunyadi, sp. nov., A. halongensis Páll-Gergely & Vermeulen, sp. nov., A. hyron Páll-Gergely & Vermeulen, sp. nov., A. maasseni Páll-Gergely & Vermeulen, sp. nov., A. majuscula Páll-Gergely & Hunyadi, sp. nov., A. margaritarion Páll-Gergely & Hunyadi, sp. nov., A. megastoma Páll-Gergely & Vermeulen, sp. nov., A. occidentalis Páll-Gergely & Hunyadi, sp. nov., A. oostoma Páll-Gergely & Vermeulen, sp. nov., A. papaver Páll-Gergely & Hunyadi, sp. nov., A. parallela Páll-Gergely & Hunyadi, sp. nov., A. prolixa Páll-Gergely & Hunyadi, sp. nov., A. pusilla Páll-Gergely & Hunyadi, sp. nov., A. pustulata Páll-Gergely & Hunyadi, sp. nov., A. quadridens Páll-Gergely & Vermeulen, sp. nov., A. rara Páll-Gergely & Hunyadi, sp. nov., A. reticulata Páll-Gergely & Hunyadi, sp. nov., A. somsaki Páll-Gergely & Hunyadi, sp. nov., A. steffeki Páll-Gergely & Grego, sp. nov., A. tetradon Páll-Gergely & Hunyadi, sp. nov., A. thersites Páll-Gergely & Vermeulen, sp. nov., A. tonkinospiroides Páll-Gergely & Vermeulen, sp. nov., A. tridentata Páll-Gergely & Hunyadi, sp. nov., A. tweediei Páll-Gergely & Hunyadi, sp. nov., A. uvula Páll-Gergely & Hunyadi, sp. nov., A. vandevenderi Páll-Gergely & Jochum, sp. nov., A. vitrina Páll-Gergely & Hunyadi, sp. nov., A. vomer Páll-Gergely & Hunyadi, sp. nov., A. werneri Páll-Gergely & Hunyadi, sp. nov. Angustopila subelevata Páll-Gergely & Hunyadi, 2015 is moved to the synonymy of Angustopila elevata (F. G. Thompson & Upatham, 1997), and A. singuladentis Inkhavilay & Panha, 2016 is a junior synonym of A. fabella Páll-Gergely & Hunyadi, 2015. Three species, namely A. elevata, A. fabella and A. szekeresi, are widespread over several hundred kilometres while some other species (A. huoyani, A. parallela sp. nov., A. cavicola sp. nov.) are known from just two sites a few hundred kilometres apart. All others are small range or single-site endemics. The reproductive anatomy of A. erawanica sp. nov. is described.

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. ? 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 The cosmopolitan littoral earthworm Pontodrilus litoralis is distributed in tropical and sub-tropical coastal habitats, whereas P. longissimus is reported only in the Thai-Malay coastal line. In the present study, we examined the difference in salinity effect on the survival rate, wet weight (hereafter weight) change, behaviour, and osmolality of these two Pontodrilus species. A 28 d exposure to varying salinity concentration (0–50 ppt) revealed that P. litoralis is able to survive over a wide salinity range than P. longissimus, with the latter species exhibiting a low survival rate over the same salinity range. During short-term exposure (0–96 h) to a salinity of less than 30 ppt, P. litoralis exhibited weight gain and this was significant in the first 12 h of exposure. However, P. longissimus gained weight when exposed to salinity at under 10 ppt in the first 72 h of exposure. The two species of Pontodrilus behaved differently when exposed to different salinities. The coelomic fluid osmolarity of Pontodrilus was related to the exposure medium and was mostly maintained as hyperosmotic to the external medium over the range of salinities tested. This study shows how two different species of the littoral earthworm genus Pontodrilus respond to a change in salinity, which may explain their dispersal pattern and shape their distribution pattern throughout Southeast Asia.

Abstract 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.

Thailand is located at the crossroads of several biogeographical regions, and boasts a high level of biodiversity, especially among the malacofauna. The most recent checklist of land snail species in Thailand was compiled more than twenty years ago, and so this checklist needs revision and the addition of newly discovered taxa. This study updates the taxonomy and species list of the operculated land snail family Pupinidae from Thailand. This snail family is diverse and abundant, and can be found in various natural habitats in Southeast Asia. Although the taxonomy of some Southeast Asian pupinid genera has been reviewed, studies of Pupina Vignard, 1829, which contains the highest number of species, and a lesser-known genus Pupinella Gray, 1850 are still lacking. Herein we present an annotated checklist with an up-to-date systematic framework of the Pupinidae in Thailand based on both field investigations and literature surveys, and include the taxonomic treatment of all Pupina and Pupinella species from mainland Southeast Asia. This annotated checklist contains 30 nominal species and two subspecies from seven genera currently known to occur in Thailand. We describe two species of Pseudopomatias (P. doiangkhangensis Jirapatrasilp, sp. nov. and P. pallgergelyi Jirapatrasilp, sp. nov.), five species and one subspecies of Pupina (P. bensoni Jirapatrasilp, sp. nov., P. bilabiata Jirapatrasilp, sp. nov., P. godwinausteni Jirapatrasilp, sp. nov., P. latisulci Jirapatrasilp, sp. nov., P. stoliczkai Jirapatrasilp, sp. nov., and P. dorri isanensis Jirapatrasilp, ssp. nov.) as new to science. New records of Coptocheilus sumatranus, Pupinella mansuyi, and Rhaphaulus tonkinensis are also reported from Thailand. The mainland Southeast Asian Pupina species are classified into three species groups (Pupina artata group, Pupina arula group, and Pupina aureola group) based on the distinction of shell teeth and canals, and operculum. Three species formerly in Pupina from Vietnam are allocated to Pupinella (P. illustris comb. nov., P. sonlaensis comb. nov., and P. thaitranbaii comb. nov.) due to the presence of a funnel-like anterior canal.

Salween River basin’s karst ecosystems in southeastern Myanmar remain largely unexplored and are likely to harbour a high terrestrial snail diversity that are often associated with high levels of snail endemism. Here, an outstanding group of new karst-associated terrestrial snails, Burmochlamys gen. nov., are discovered. A study of the comparative morphological and anatomical data reveals that the reproductive tract and radula of this new genus are closely related to the helicarionid genus Sophina Benson, 1859 but shell morphology (shape, size, and sculpture) and mantle extensions are distinct from the latter genus. Burmochlamys gen. nov. now consists of four known nominal species, B. cassidula comb. nov., B. cauisa comb. nov., B. perpaula comb. nov., and B. poongee comb. nov., and five new species; B. albida sp. nov., B. fasciola sp. nov., B. moulmeinica sp. nov., B. versicolor sp. nov., and B. whitteni sp. nov. The highlight is that the members of the new genus show site-specific endemism, being restricted to karstic habitat islands of the Salween River basin. In addition, the discovery supports that the unique and complex structure of Salween River basin’s karst ecosystems are habitats in which the terrestrial malacofauna have speciated and become endemic.

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.

Species of colourful arboreal snails of the genus Amphidromus from Southeast Asia commonly exhibit high intraspecific variation in shell morphology. Although highly polymorphic Amphidromus specimens with different colouration have been collected at the same locality and were revealed to possess similar genital organs, there is yet no morphometric or DNA analyses of these different shell morphs. This study is the first to reveal that both striped and stripeless morphs of A. cruentatus from Laos and Vietnam belong to the same mitochondrial (COI and 16S rRNA) lineage. Although the shell colouration between the striped and stripeless morphs is markedly different, morphometric and shell outline-based analyses indicated an overall similarity in shell shape. We also revised the systematics of A. cruentatus, in which we treated similar related species, namely A. eudeli, A. fuscolabris, A. thakhekensis, A. gerberi bolovenensis, A. goldbergi, A. pengzhuoani, A. eichhorsti and A. pankowskiae as junior synonyms of A. cruentatus. Amphidromus daoae, A. anhdaoorum, A. stungtrengensis, A. yangbayensis and A. yenlinhae, which were formerly regarded as junior synonyms, are considered as species different from A. cruentatus based on shell morphology and morphometric analyses. Preliminary phylogenetic analyses also retrieved some Amphidromus species groups as distinct mitochondrial lineages.