Movement disorders in Indochina: Resource challenges and future solutions.

Movement disorders are a major cause of disability worldwide and their increasing prevalence predicts a substantial future burden of care. Impactful patient care requires availability of, and accessibility to, effective medications, knowledge, and disease awareness among both medical professionals and patients, driven by skilled personnel to harness and manage resources. The highest burden of movement disorders is in low-to-middle income countries where resources are often limited and infrastructure is insufficient to meet growing demands. This article focuses on the specific challenges faced in the management and delivery of care for movement disorders in Indochina, the mainland region of Southeast Asia comprising the neighboring countries of Cambodia, Laos, Malaysia, Myanmar, Thailand, and Vietnam. The first Indochina Movement Disorders Conference was held in August 2022 in Ho Chi Minh City, Vietnam, to provide a platform to better understand the situation in the region. Future management of movement disorders in Indochina will require progressive adaptation of existing practices to reflect modern approaches to care delivery. Digital technologies offer an opportunity to strengthen these processes and address the challenges identified in the region. Ultimately, a long-term collaborative approach by regional healthcare providers is key.

Mapping the Contribution of Biomass Burning to Persistent Organic Pollutants in the Air of the Indo-China Peninsula Based on a Passive Air Monitoring Network.

Biomass burning (BB) is an important source of atmospheric persistent organic pollutants (POPs) across the world. However, there are few field-based regional studies regarding the POPs released from BB. Due to the current limitations of emission factors and satellites, the contribution of BB to airborne POPs is still not well understood. In this study, with the simultaneous monitoring of BB biomarkers and POPs based on polyurethane foam-based passive air sampling technique, we mapped the contribution of BB to polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in the Indo-China Peninsula. Spearman correlations between levoglucosan and 16 PCBs (rs = 0.264-0.767, p < 0.05) and 2 OCPs (rs = 0.250-0.328, p < 0.05) confirmed that BB may facilitate POP emissions. Source apportionment indicated that BB contributed 9.3% to the total PCB and OCP mass. The high contribution of positive matrix factorization-resolved BB to PCBs and OCPs was almost consistent with their concentration distributions in the open BB season but not completely consistent with those in the pre-monsoon and/or monsoon seasons. Their contribution distributions may reflect the use history and geographic distribution in secondary sources of POPs. The field-based contribution dataset of BB to POPs is significant in improving regional BB emission inventories and model prediction.

Emission growth and drivers in Mainland Southeast Asian countries.

Mainland Southeast Asian (MSEA) countries (Cambodia, Laos, Thailand, Myanmar, and Vietnam) are likely to become one of the next hotspots for emission reduction, since CO2 emissions in this area will have a two-thirds increase by 2040 due to rapid economy growth and associated energy consumption. As one of the most vulnerable areas to climate change, MSEA countries need to develop low-carbon roadmaps based on accurate emission data. This study provides emission inventories for MSEA countries for 2010-2019, based on the IPCC territorial emission accounting approach , including emissions from five types of fuels (i.e., coal, crude oil, oil products, natural gas, and biofuels & waste) used in 47 economic sectors. The results show that the emissions in MSEA countries are on the rise, with average annual growth rates ranging from 2.5% in Thailand to 19.3% in Laos. Biomass is one of the most important sources of carbon emissions, contributing between 11.8% and 76.7% of total carbon emissions, but its share has been declining in most countries, whereas the share of emissions from coal has risen sharply in Laos, Vietnam, and Cambodia. We further examine the drivers behind the changes in emissions using index decomposition analysis. Economic growth was the strongest driver of growth in emissions, while population growth has only had a small effect on emission growth. Energy intensity varies widely across nations, but only significantly reduced CO2 emission growth in Thailand. The secondary sector considerable contributed to an increase in CO2 emissions in Laos and Vietnam, while the tertiary sector only moderately contributed to emissions in Thailand. Our study provides a better understanding of the composition and underlying factors of emission growth in MSEA countries, this could shape their low-carbon development pathway. Our results could also inform other emerging economies, which may become emission hotspots in the next decades, to develop low-carbon roadmaps, thereby contributing to the achievement of global climate change targets.

Opening a door to the spatiotemporal history of plants from the tropical Indochina Peninsula to subtropical China.

The complexity of global biodiversity in the tropical Indochina Peninsula and subtropical China bioregions has fascinated biologists for decades, but little is known about the spatiotemporal patterns in these regions. Accordingly, the aims of present study were to investigate the evolutionary and distribution patterns of Engelhardia in these regions and establish a model for examining biogeographic patterns and geological events throughout the tropical Indochina Peninsula and subtropical China. The effects of geological events occurring in the area between the Indochina Peninsula and subtropical China bioregions on the two trees species (i.e., E. roxburghiana and E. fenzelii) were evaluated. A robust phylogenetic framework of 884 individuals from 79 populations was used to generate time-calibrated cytoplasmic and nuclear phylogenetic frameworks based on cpDNA, nrDNA, and nSSR data, respectively. When considered along with ancestral area reconstructions, the genetic data were also used to assess and reconstruct the species' population genetic structure and diversity. These analyses yielded important information about the (1) historical distribution relationships between the tropical and subtropical flora of China; (2) effects of the East Asian summer monsoon (EASM) on the evolutionary history of Asia's plants; and (3) importance of biogeography in conservation planning. Although cytoplasmic-nuclear discordance indicated cpDNA and nrDNA were subject to distinct evolutionary mechanisms that reflected respective evolutionary histories of the plastid and nuclear genomes of prior demographic and biogeographic events. The tropical elements of Engelhardia occupied the Indochina Peninsula during the early Eocene, whereas the subtropical elements were transformed from the tropical elements during Miocene cooling and the onset of the EASM at the Oligocene-Miocene boundary, intensified during the late Miocene and Pliocene, facilitating the transformation of Engelhardia from the tropical Indochina Peninsula to subtropical China. Demographic history provided insights into prominent planning frameworks in conservation biology, namely that subtropical China functioned as a refugium during past climate oscillations and will continue to serve in this capacity in the future.

One northward, one southward: Contrasting biogeographical history in two benthic freshwater fish genera across Southeast Asia (Teleostei: Cobitoidea: Nemacheilus, Pangio).

Southeast Asia is one of the world's biodiversity hotspots, and the high level of diversity and endemism was reached by colonisation events as well as internal diversification. We investigate the phylogenetic relationships and biogeographic history of the loach genus Nemacheilus, which is widely distributed and common across freshwaters of Southeast Asia. In addition we present the ancestral range reconstruction of the related loach genus Pangio that commonly occurs in the same region as Nemacheilus. Our results reveal that the species currently classified as Nemacheilus in fact are a polyphyletic assemblage; most species are now retaining in a monophyletic Nemacheilus sensu stricto and five species belong to different lineages. We further indicate the existence of hidden diversity within Nemacheilus in the form of several undescribed species. Three major clades (Selangoricus, Masyae and Ornatus) are found within the genus Nemacheilus sensu stricto. These clades generally correspond to the species groups formerly defined on the basis of their pigmentation pattern. The biogeographic analyses show that Nemacheilus most likely originated in mainland Southeast Asia and subsequently expanded in a southward direction to Borneo, Sumatra and Java and the southern Malay Peninsula. In contrast, the genus Pangio originated in Sundaland, from where it extended several times northwards into Indochina and to northern India. Our results demonstrate that small freshwater fishes with restricted dispersal ability are very helpful for the reconstruction of biogeographic history. The contrasting biogeographic history of these two groups of small, benthic and related fish show how complex and case-specific the processes that lead to the biodiversity richness of Southeast Asia are.

COVID-19 and Tropical Infection: Complexity and Concurrence.

COVID-19 is a newly emerging pandemic caused by a novel coronavirus. After its first report in China in December 2019, the disease already spread and affected more than 200 countries worldwide. It correlates with different phenotypes ranging from an acute febrile illness to severe respiratory problems. Often, patients with COVID-19 suffer from metabolic disorders, and this can result in a more severe clinical course. COVID-19 might also co-occur with other common diseases in different settings. In tropical countries, COVID-19 has already affected thousands of local populations. Tropical diseases such as dengue and tuberculosis can modify the clinical presentation of COVID-19 and result in difficulty in the diagnosis and treatment of the patients. The complexity of concurrence between COVID-19 and tropical diseases is, thus, a matter of concern in tropical medicine. This chapter is devoted to discussing problems surrounding the management of COVID-19 in tropical countries. To exemplify the effects of COVID-19 on tropical countries, the authors would show how COVID-19 has affected Indochina, a large tropical area.

Investigation of multiple infections with zoonotic pathogens of rodents in northern Vietnam.

BACKGROUND & OBJECTIVES: Rodents are important reservoir hosts for several zoonotic pathogens such as Rickettsia, Leptospira and Bartonella. Studies on the prevalence of zoonotic pathogens in Vietnam are data deficient, and there is a scarcity of data on multiple co-infections of zoonotic pathogens to date. This study examined the prevalence of Rickettsia spp., Leptospira spp., and Bartonella spp. and the co-infection of these pathogens in rodents captured in three provinces of northern Vietnam - Ha Giang, Lao Cai and Cao Bang. METHODS: In total, 133 rodents of 25 species were screened for pathogen prevalence by real-time PCR. RESULTS: Very high infection rates were found for each pathogen, with 42 of 133 rodents (31.6%) positive for Bartonella and 33 of 133 (24.8%) positive for Rickettsia (5.3% were positive for Rickettsia typhi, and 19.5% were infected with Rickettsia spotted fever group). Additionally, 24 rodents (18%) were positive for Leptospira. Double infection among these three pathogens was found in 26 of 133 rodents (18.8%), with the highest dual infection rates for Rickettsia and Bartonella co-infection (40%) and Leptospira and Bartonella co-infection (up to 40%), followed by Rickettsia and Leptospira co-infection (20% of animals investigated). One case of triple infection was documented for a house rat (Rattus cf. rattus species group) trapped in Ha Giang province. INTERPRETATION & CONCLUSION: Our survey indicates that rodents in northern Vietnam may host multiple zoonotic pathogens simultaneously; thus, rodents contribute significantly to the increased risk of transmission of multiple zoonotic infections from animals to humans.

Rivers of Indochina as potential drivers of lineage diversification in the spotted flying lizard (Draco maculatus) species complex.

Southeast Asia hosts a rich concentration of biodiversity within multiple biodiversity hotspots. Indochina, a region with remarkably high levels of in situ diversification, possesses five major rivers (Ayeyarwady, Chiang Mai, Mekong, Red, and Salween), several of which coincide with phylogenetic breaks of terrestrial taxa. Draco maculatus possesses a range that stretches across Indochina, which widespread geographic distribution along with potential discrete variation within subspecies alludes to the possibility of this taxon constituting multiple divergent lineages. Using sequence data from three mitochondrial (12S, 16S, and ND2) and three nuclear (BDNF, CMOS, and PNN) genes, we provide the first estimated phylogeny of this hypothesized species complex and examine its phylogeographic architecture with maximum likelihood and Bayes factor delimitation (BFD) approaches. Our results support multiple divergent lineages with phylogenetic breaks coincident with rivers, indicating that river barriers may be contributing to the elevated levels of in situ diversification of Indochina.

Secondary contact and genomic admixture between rhesus and long-tailed macaques in the Indochina Peninsula.

Understanding the process and consequences of hybridization is one of the major challenges in evolutionary biology. A growing body of literature has reported evidence of ancient hybridization events or natural hybrid zones in primates, including humans; however, we still have relatively limited knowledge about the pattern and history of admixture because there have been little studies that simultaneously achieved genome-scale analysis and a geographically wide sampling of wild populations. Our study applied double-digest restriction site-associated DNA sequencing to samples from the six localities in and around the provisional hybrid zone of rhesus and long-tailed macaques and evaluated population structure, phylogenetic relationships, demographic history, and geographic clines of morphology and allele frequencies. A latitudinal gradient of genetic components was observed, highlighting the transition from rhesus (north) to long-tailed macaque distribution (south) as well as the presence of one northern population of long-tailed macaques exhibiting unique genetic structure. Interspecific gene flow was estimated to have recently occurred after an isolation period, and the migration rate from rhesus to long-tailed macaques was slightly greater than in the opposite direction. Although some rhesus macaque-biased alleles have widely introgressed into long-tailed macaque populations, the inflection points of allele frequencies have been observed as concentrated around the traditionally recognized interspecific boundary where morphology discontinuously changed; this pattern was more pronounced in the X chromosome than in autosomes. Thus, due to geographic separation before secondary contact, reproductive isolation could have evolved, contributing to the maintenance of an interspecific boundary and species-specific morphological characteristics.

Seismic damage to ancient monuments in Chiang Saen (Northern Thailand): implication for historical earthquakes in Golden Triangle area.

Over the last few decades, three moderate earthquakes (Mw greater than 6.0) occurred in and around the Golden Triangle area (including Myanmar, Thailand and Lao PDR) causing unprecedented damage and loss of lives in the epicentral region. In addition to the damage to modern structures, most heritage structures in Chiang Saen, a major city of the Lan Na kingdom (from the thirteenth to the eighteenth century), were also affected. This work is intended to present observed historical structure damage from recent earthquakes, which could provide evidence for the severity of historical earthquakes from the thirteenth to the eighteenth century. Based on historical records, geological evidence and observed damage to ancient monuments in this historic town, existing heritage stupas and temples constructed since the fourteenth century sustained only minor to moderate damage from these historical earthquakes. Considering the seismic vulnerability of these historical monuments, Chiang Saen might have never been subjected to severe ground shaking greater than MMI intensity VII, similar to the major earthquake in 460 A.D. along the Mae Chan fault, which was responsible for the large-scale liquefaction and inundation of ancient Yonok town. This information could be important for paleoseismological and historical earthquake research to constrain the recurrence interval of major active faults in this area. This article is part of the theme issue 'Environmental loading of heritage structures'.

Assessment of the hybridization between rhesus (Macaca mulatta) and long-tailed macaques (M. fascicularis) based on morphological characters.

OBJECTIVES: Hybridization between rhesus (Macaca mulatta) and long-tailed (M. fascicularis) macaques has become a focal point of interest. The majority of such studies have evaluated their genetics, but not their morphological characters. MATERIALS AND METHODS: We analyzed morphological characters of eight free-ranging populations of Indochinese rhesus and long-tailed macaques distributed at the proposed hybrid zone (15.75-21.58° N) in comparison with one population each of Chinese and Indian-derived rhesus macaques and three populations of Sundaic long-tailed macaques. RESULTS: Chinese and Indian rhesus macaques had a heavier body mass, longer crown-rump length, shorter relative facial length and relative tail length, and a greater contrast of reddish and yellowish dorsal pelage color than the Sundaic long-tailed macaques for which the latter three parameters could be used to visually discriminate between the two species. Although the morphological characters of Indochinese rhesus and long-tailed macaques were intermediate between the Chinese/Indian rhesus and Sundaic long-tailed macaques, they were more similar to their respective conspecifics. The species-specific characters of a shorter tail (<70%) and a bipartite pelage color pattern were retained in the Indochinese rhesus macaques while the longer tail (>90%) and no bipartite pattern was found in the Indochinese long-tailed macaques. No morphological cline was observed across the species and the variations were abrupt to some extent. DISCUSSION: The hybridization between rhesus and long-tailed macaques may be results of multiple contacts and isolations over a long period of time, thus their evolutionary history should not be drawn solely by genetic or morphological analysis.

A new species of the Cyrtodactyluschauquangensis group (Squamata, Gekkonidae) from the borderlands of extreme northern Thailand.

Phylogenetic and morphological analyses delimit and diagnose, respectively, a new population of a karst-dwelling Cyrtodactylus from extreme northern Thailand. The new species, Cyrtodactylusphamiensis sp. nov., of the chauquangensis group inhabits karst caves and outcroppings and karst vegetation in the vicinity of Pha Mi Village in Chiang Rai Province, Thailand. Within the chauquangensis group, Cyrtodactylusphamiensis sp. nov. is the earliest diverging species of a strongly supported clade composed of the granite-dwelling C.doisuthep and the karst-dwelling sister species Cyrtodactylus sp. 6 and C.erythrops. The nearly continuous karstic habitat between the type locality of Cyrtodactylusphamiensis sp. nov. and its close relatives Cyrtodactylus sp. 6 and C.erythrops, extends for approximately 200 km along the border region of Thailand and the eastern limit of the Shan Plateau of Myanmar. Further exploration of this region, especially the entire eastern ~ 95% of the Shan Plateau, will undoubtably recover new populations whose species status will need evaluation. As in all other countries of Indochina and northern Sundaland, the continual discovery of new karst-dwelling populations of Cyrtodactylus shows no signs of tapering off, even in relatively well-collected areas. This only highlights the conservation priority that these unique karstic landscapes still lack on a large scale across all of Asia.

Taxonomic revision of Camellia (Theaceae) in Thailand.

Natural plants of Camellia (Theaceae) in Thailand are taxonomically revised with a key, a distribution map, descriptions, specimens examined, and figures of living plants and/or dry specimens. Nine taxa comprising seven species and two varieties are recognized, including C.caudata, C.connata, C.furfuracea, C.kissi, C.kissivar.confusa, C.laotica, C.sinensisvar.assamica, C.suddeeana, and C.taliensis. Camelliacaudata and C.laotica are new records to Thailand, and C.connata and C.suddeeana are endemic to the country. Formerly recorded C.pleurocarpa and C.tenii are excluded from Thai flora because of misidentification, and C.oleifera and C.sinensis are merely cultivated in the country. Morphological descriptions of C.connata and C.laotica are improved based on additional collections examined.

A new species of Raorchestes (Anura, Rhacophoridae) from Yunnan Province, China.

A new bush frog species is described from Yunnan, China, based on phylogenetic analyses, species delimitation analyses, and morphological comparisons. Raorchesteshekouensissp. nov. is distinguished from all other congeners by a combination of 11 morphological characters. The new species brings the current number of Raorchestes species in China to ten, nine of which are distributed in Yunnan. Molecular analyses supported an unnamed lineage previously recorded as "Raorchestesgryllus" in northern Vietnam. Further studies including additional samples are necessary to clarify the species diversity and boundaries of Raorchestes in China and Indochina.

Biodiversity and Spatiotemporal Variations of Mecoptera in Thailand: Influences of Elevation and Climatic Factors.

Ecological analyses of the small and lesser-known insect order Mecoptera in Thailand are presented. Specimens were collected monthly over a period of 12 consecutive months, using both Malaise and pan traps, from 29 sampling sites located in 18 national parks throughout Thailand. A total of 21 species in four genera were identified from 797 specimens, including Panorpa (1 species), Neopanorpa (18 species), Bittacus (1 species), and Terrobittacus (1 species), with the latter genus representing a new genus record to Thailand. Neopanorpa harmandi, N. siamensis, N. byersi, and N. malaisei were the most abundant species, representing 27.4%, 11.3%, 10.3% and 8.8% of the total specimens, respectively. The species with the highest frequency, as indicated by the high percentage of species occurrence (%SO), was N. siamensis (51%), followed by N. byersi (34%), N. harmandi (34%), N. spatulata (27%), and N. inchoata (27%). Eleven species (52%) exhibited specific regional occurrences. N. tuberosa and N. siamensis had the widest distribution, being found in almost all regions except for western and southern regions for the first and second species, respectively. The seasonal species richness of Mecoptera was high during the rainy season in the northern, northeastern, central, eastern, and western regions, with the highest richness observed in July (15 species), followed by the hot (10 species) and cold seasons (7 species), while there was no significant difference in species richness between seasons in the southern region. Multiple regression models revealed a negative association between species richness and abundance of Mecoptera with both elevation and temperature, and a positive association between rainfall and species evenness. It is predicted that climatic changes will have a detrimental effect on the mecopteran community. The results of this study enhance the understanding of the ecological aspects of Mecoptera, offering crucial insights into its biodiversity and distribution, which are vital for conservation and forest management.

Pisachini planthoppers of Vietnam: new records of Pisacha and a new Goniopsarites species from Central Vietnam (Hemiptera, Fulgoromorpha, Nogodinidae).

Two planthopper species of the family Nogodinidae are added to the fauna of Vietnam, both from two localities in Thua Thien-Hue Province: Bach Ma National Park and Phong Dien District. The first species belongs to Goniopsarites Meng, Wang & Wang, 2014, G.mientrunganus Constant & Pham, sp. nov., and the second belongs to Pisacha Distant, 1906, P.yinggensis Meng, Wang & Wang, 2014. Pisachayinggensis was previously recorded from Hainan Island, China. These new records greatly extend the distribution of both genera, which were known from southern China, Hainan and North Vietnam, to the south, reaching the mid area of Central Vietnam. Sexual dimorphism is reported in P.yinggensis for the first time. Illustrations of habitus and male terminalia of the new species are given as well as distribution maps and photographs of live specimens and their habitat. The family Nogodinidae now comprises nine species in Vietnam, with three of them present in Bach Ma National Park.

Parahiraciini planthoppers with elongate head from Vietnam: a new genus and species Pumatiraciavenosa gen. et sp. nov. and first record of Laohiraciaacuta Constant, 2021 (Hemiptera, Fulgoromorpha, Issidae).

The new genus Pumatiraciagen. nov. is described to accommodate a new species, P.venosagen. et sp. nov. from Pu Mat National Park in Vietnam. The new genus is placed in the subtribe Parahiraciina of the Parahiraciini. It is compared with the genera Laohiracia Constant, 2021, Macrodarumoides Che, Zhang et Wang, 2012, Pseudochoutagus Che, Zhang et Wang, 2011, and Rostrolatum Che, Zhang et Wang, 2020 with which it shares possessing an elongate head. Illustrations of habitus, details, and male genitalia are given as well as a distribution map and photographs of the habitat. Laohiraciaacuta Constant, 2021 is recorded for the first time from Vietnam, Pu Luong National Park; living specimens and habitat are illustrated, and the distribution map updated. The Parahiraciini fauna of Vietnam now comprises 14 species belonging to 11 genera.

Taxonomic revision of Camellialangbianensis (Theaceae) with four new synonyms.

Based on analysis of morphologically diagnostic characters, Camellialangbianensis, a yellow camellia native to southern Vietnam, is taxonomically revised to include four new heterotypic synonyms: C.decora, C.dongnaiensis, C.oconoriana and C.tadungensis. Camelliavidalii is retained in the synonymy of C.langbianensis. Updated description and distribution map for C.langbianensis are provided.

Integrated phylogenetic analyses reveal the evolutionary, biogeographic, and diversification history of Asian warty treefrog genus Theloderma (Anura, Rhacophoridae).

Asian warty treefrogs, genus Theloderma, are morphologically variable arboreal frogs endemic to Southeast Asia and Southern China. However, integrated systematic studies are lacking, and knowledge of the genus in terms of diversity, origin, and historical diversification remains limited. To address these knowledge gaps, we used three mitochondrial and five nuclear gene fragments to reconstruct the Theloderma phylogeny, estimate divergence times, and examine the biogeography of the genus. Phylogenetic and species delimitation analyses suggest that the genus Theloderma comprises three major clades corresponding to two subgenera and seven species groups, and mPTP identified at least 12 putative cryptic species, suggesting that species diversity has been underestimated. Biogeographic analyses indicated that most recent common ancestor of Theloderma originated in the Indochina Peninsula during the Middle Oligocene (ca. 27.77 Ma) and the splitting of Clade A to C occurred in the Late Oligocene (ca. 23.55-25.57 Ma). Current biogeographic patterns result from two distinct processes: in situ diversification in the Indochina Peninsula and dispersal in multiple areas, namely southward dispersal to the Malay Peninsula and Borneo, northeastward dispersal to Southern China, northward dispersal to the Himalayas, and dispersal from Southern China to the Indochina Peninsula. Ancestral character reconstruction suggests that the ancestor of Theloderma may have possessed a small body size, rough dorsal skin, and absence of vomerine teeth and hand webbing, and that these four characters have undergone multiple evolutions. Principal component analysis based on eight bioclimatic variables did not clearly distinguish the three major clades of Theloderma, suggesting that species in these clades may occupy similar climatic ecological niches. Our research highlights the importance of orogeny and paleoclimatic changes, in shaping amphibian biodiversity in mountain ecosystems.

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.