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Accurately delimiting species and their geographic ranges is imperative for conservation, especially in areas experiencing rapid habitat loss. Southeast Asia currently has one of the highest rates of deforestation in the world, is home to multiple biodiversity hotspots, and the majority of its countries have developing economies with limited resources for biodiversity conservation. Thus, accurately delimiting species and their ranges is particularly important in this region. We examined genetic and morphological variation in the widespread frog species Sylvirana nigrovittata (and its long-treated junior synonym S. mortenseni) with the goal of clarifying its taxonomic content and geographic range boundaries for conservation. We present evidence that the current concept of S. nigrovittata contains at least eight species, two of which are each known from only two localities, but that S. mortenseni is more geographically widespread than currently realized. Five of these species are described as new to science.

A new karst-dwelling bent-toed gecko of the Cyrtodactylus intermedius group is described from Khlong Hat District, Sa Kaeo Province, eastern Thailand, based on an integrative taxonomic analysis of genetic data and morphological characteristics. Phylogenetic analyses using the mitochondrial NADH dehydrogenase subunit 2 (ND2) gene revealed that topotypes of C. intermedius were sister to a clade containing C. kulenensis from Cambodia, an unnamed lineage from Sakaerat Biosphere Reserve in Nakhon Ratchasima Province, Thailand, and the Khlong Hat lineage described here as Cyrtodactylus khlonghatensis sp. nov. Multivariate analyses of morphometric and meristic characters showed that C. khlonghatensis sp. nov. is morphologically distinct from all other species in the group by having the combination of SVL 76.5–82.8 mm in adult males and 88.5 mm in an adult female; eight supralabial and nine infralabial scales; 30–32 paravertebral tubercles; 20 or 21 longitudinal rows of dorsal tubercles; 43 or 44 ventral scales; seven or eight expanded subdigital lamellae on the 4 th toe; 12 unmodified subdigital lamellae on the 4 th toe; 19 or 20 total subdigital lamellae on the 4 th toe; 31 or 32 total number of enlarged femoral scales; enlarged femoral and precloacal scales continuous; 6–8 pore-bearing precloacal scales in males; three or four rows of enlarged post-precloacal scales; 1–3 postcloacal tubercles; proximal femoral scales less than one-half the size of distal femoral scales; absence of interdigital pocketing between digits of forefeet and hindfeet; and posterior border of the nuchal loop rounded. Uncorrected pairwise genetic divergences ( p -distances) between the new species and other species of the intermedius group ranged from 4.73–22.55%. The discovery of this new species exclusively in isolated karst formations from the Thai-Cambodia border suggests that there may be further undiscovered Cyrtodactylus in unexplored karst landscapes along the border of eastern Thailand and western Cambodia.

Divergence dating analyses in systematics provide a framework to develop and test biogeographic hypotheses regarding speciation. However, as molecular datasets grow from multilocus to genomic, sample sizes decrease due to computational burdens, and the testing of fine-scale biogeographic hypotheses becomes difficult. In this study, we use coalescent demographic models to investigate the diversification of poorly known rice paddy snakes from Southeast Asia (Homalopsidae: Hypsiscopus ), which have conflicting dates of origin based on previous studies. We use coalescent modeling to test the hypothesis that Hypsiscopus diversified 2.5 mya during the Khorat Plateau uplift in Thailand. Additionally, we use ecological niche analyses to identify potential differences in the niche space of the two most widely distributed species in the past and present. Our results suggest Hypsiscopus diversified ~ 2.4 mya, supporting that the Khorat Plateau may have initiated the diversification of rice paddy snakes. We also find significant niche differentiation and shifts between species of Hypsiscopus , indicating that environmental differences may have sustained differentiation of this genus after the Khorat Plateau uplift. Our study expands on the diversification history of snakes in Southeast Asia, and highlights how results from smaller multilocus datasets can be useful in developing and testing biogeographic hypotheses alongside genomic datasets.

A new species of the Cnemaspis siamensis group is described from Wang Khrachae District, Kanchanaburi Province, western Thailand based on morphological and molecular data. The new species, Cnemaspis enneaporus Rujirawan, Aksornneam & Aowphol, sp. nov. , is distinguished from other species in the C. siamensis group by having the combination of SVL 42.2 mm in adult male ( n = 1), 43.7 mm in adult female ( n = 1); eight supralabials; seven or eight infralabials; ventral scales smooth; nine continuous precloacal pores in male; 17 or 18 paravertebral tubercles linearly arranged; tubercles on lower flanks present; lateral caudal furrows present; no caudal tubercles in the lateral furrows; ventrolateral caudal tubercles present on original portion of tail; caudal tubercles not encircling tail; subcaudals smooth; no enlarged median subcaudal row; two postcloacal tubercles on each side of tail; no shield-like subtibial scales; subtibial scales smooth; no enlarged submetatarsal scales; 26–28 subdigital lamellae on the fourth toe; sexually dimorphic for dorsal and ventral colour pattern; prescapular marking absent; gular marking absent; and yellow colouration in life on all ventral surfaces of head, body and tail in adult male. Phylogenetically, the new species is recovered as the sister taxon to C. huaseesom , but the two species are separated by 8.3–9.4% uncorrected pairwise genetic divergences in the mitochondrial NADH dehydrogenase subunit 2 gene and flanking tRNAs.

The taxonomy and geographic distributions of species of crab-eating frogs ( Fejervarya cancrivora complex) in mainland Southeast Asia have been highly uncertain. Three taxonomic names are used in recent literature ( F. cancrivora , F. raja , and F. moodiei ) but the applications of these names to localities has been inconsistent, especially owing to the lack of available molecular data for F. raja . Morphometric and mitochondrial DNA variation was examined in these frogs, including name-bearing types and topotypes of all three species. Findings corroborate evidence for the existence of two species in coastal mainland Southeast Asia, with F. moodiei having a wide geographic distribution and F. cancrivora sensu stricto occurring only in extreme southern Thailand and peninsular Malaysia. Fejervarya raja is shown to be only a large-bodied population of F. cancrivora sensu stricto and is synonymized with that species. Revised descriptions of F. moodiei and F. cancrivora sensu stricto are provided.

The disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused dramatic amphibian population declines and extinctions in Australia, Central and North America, and Europe. Bd is associated with >200 species extinctions of amphibians, but not all species that become infected are susceptible to the disease. Specifically, Bd has rapidly emerged in some areas of the world, such as in Australia, USA, and throughout Central and South America, causing population and species collapse. The mechanism behind the rapid global emergence of the disease is poorly understood, in part due to an incomplete picture of the global distribution of Bd. At present, there is a considerable amount of geographic bias in survey effort for Bd, with Asia being the most neglected continent. To date, Bd surveys have been published for few Asian countries, and infected amphibians have been reported only from Indonesia, South Korea, China and Japan. Thus far, there have been no substantiated reports of enigmatic or suspected disease-caused population declines of the kind that has been attributed to Bd in other areas. In order to gain a more detailed picture of the distribution of Bd in Asia, we undertook a widespread, opportunistic survey of over 3,000 amphibians for Bd throughout Asia and adjoining Papua New Guinea. Survey sites spanned 15 countries, approximately 36° latitude, 111° longitude, and over 2000 m in elevation. Bd prevalence was very low throughout our survey area (2.35% overall) and infected animals were not clumped as would be expected in epizootic events. This suggests that Bd is either newly emerging in Asia, endemic at low prevalence, or that some other ecological factor is preventing Bd from fully invading Asian amphibians. The current observed pattern in Asia differs from that in many other parts of the world.

Aim: To infer the colonization history of reed frog species endemic to the oceanic islands of São Tomé and Príncipe, Hyperolius molleri and H. thomensis, we quantified phylogeographical structure in the closely related H. cinnamomeoventris species complex, which is broadly distributed across continental Central Africa. Location: The Lower Guineo-Congolian Forest and the Gulf of Guinea islands of São Tomé and Príncipe, Central Africa. Methods: We combined gene and species tree analyses to investigate diversity and divergence among H. cinnamomeoventris populations, to identify the most likely dispersal route to the islands, and to infer the order in which the islands were colonized. One of the endemics (H. molleri) is distributed on both islands and we quantified genetic divergence between populations. Results: We recovered three clades in H. cinnamomeoventris corresponding to West-Central, North/East-Central and South-Central Africa. The island endemics form a monophyletic group most closely related to the West-Central African H. cinnamomeoventris clade. Populations of H. molleri on São Tomé and Príncipe are reciprocally monophyletic at mitochondrial loci but nuclear gene trees do not support this divergence. Main conclusions: Genetic structure in the H. cinnamomeoventris species complex coincides with biogeographical barriers identified in previous studies of Central African rain forest taxa. Individual gene tree and species tree analyses support a single dispersal event from the Ogooué or Congo river basins (West-Central Africa) to the island of São Tomé, with subsequent divergence within São Tomé and dispersal to Príncipe.

Cyrtodactylus monilatus sp. nov. is described from Si Sawat District, Kanchanaburi Province, in western Thailand. The new species superficially resembles C. zebraicus Taylor, 1962 from southern Thailand. However, differences between the new species from C. zebraicus and other congeners were supported by an integrative taxonomic analysis of molecular and morphological data. Phylogenetic analyses based on the mitochondrial NADH dehydrogenase subunit 2 (ND2) gene showed that the new species is a member of the C. oldhami group and closely related to Cyrtodactylus sp. MT468911 from Thong Pha Phum National Park, Thong Pha Phum District, Kanchanaburi Province. Uncorrected pairwise genetic divergences ( p -distances) between the new species and its congeners, including C. zebraicus , ranged from 7.7–17.7%. Cyrtodactylus monilatus sp. nov. can also be distinguished from all members of the C. oldhami group by having a unique combination of morphological characters, including a snout to vent length of 53.7–63.3 mm in adult males and 58.6–75.8 mm in adult females; 22–34 paravertebral tubercles; 34–42 ventral scales; 30–39 enlarged contiguous femoroprecloacal scales; femoral pores and precloacal pores absent in both sexes; four or five rows of postprecloacal scales; enlarged median subcaudal scales absent; weak ventrolateral folds present; 4–7 rows of paired, paravertebral, dark-brown blotches edged in yellow or yellowish white; and two rows of small, diffuse, yellow or yellowish white spots on flanks. The new species occurs in a narrow range of forest at mid to low elevations associated with karst landscapes in the Tenasserim mountain range.

A new species in the dicroglossid frog genus Limnonectes is described from Ko Pha-ngan, Ko Samui, and Ko Lanta Yai Islands in southern Thailand. Males of Limnonectes pseudodoriae sp. nov. lack a caruncle on top of the head and very closely resemble L. doriae (Boulenger, 1887) from Myanmar and western and southern Thailand. However, the new species is distinguished from L. doriae and its congeners using an integrative taxonomic approach of morphology, mitochondrial DNA, and bioacoustics. Limnonectes pseudodoriae sp. nov. differs from L. doriae and its congeners by having a unique combination of morphological characters, including body size; skin texture of the interorbital region, dorsum, and shank; toe webbing; relative size of the inner metatarsal tubercle; and coloration of the tympanum, venter, and ova. The advertisement call of the new species is also readily differentiated from that of L. doriae in temporal parameters. Limnonectes pseudodoriae sp. nov. is highly divergent in mitochondrial DNA from L. doriae and its congeners, but its phylogenetic position within the genus is not resolved. The natural history of the new species is presented, and the geographic range of L. doriae in Thailand is clarified.

Two new insular rock geckos in the genus Cnemaspis are described from Ko Samui in Surat Thani Province and Ko Similan in Phang-nga Province, southern Thailand, based on a combination of morphological and mitochondrial NADH dehydrogenase subunit 2 (ND2) data. Both new species represent divergent lineages within the Cnemaspis siamensis species group. Cnemaspis samui sp. nov. is distinguished from other species in the group by having eight or nine supralabial and infralabial scales; 5–8 pore-bearing precloacal scales in males, pores rounded; 25–27 paravertebral tubercles, arranged randomly; 22–25 subdigital lamellae under 4 th toe; enlarged median subcaudal scale row present; gular region, abdomen, limbs and subcaudal region yellowish only in males, and uncorrected pairwise divergences of 8.86–26.83% from all other species in the C. siamensis species group. Cnemaspis similan sp. nov. is distinguished from other species in the group by having eight or nine supralabial and seven or eight infralabial scales; one pore-bearing precloacal scale in males, pore rounded; 24 or 25 paravertebral tubercles, arranged randomly; 23 or 24 subdigital lamellae under 4 th toe; no enlarged median subcaudal scale row; pale yellow reticulum on head, neck, flanks, belly and limbs in male only, and uncorrected pairwise divergences of 9.34–27.11% from all other species in the C. siamensis species group. Cnemaspis samui sp. nov. is found along granitic rocky stream outcrops of Hin Lad Waterfall, Ko Samui, Gulf of Thailand, while Cnemaspis similan sp. nov. occurs in granitic rocky outcrops near Ao Nguang Chang Bay, Ko Similan, Andaman Sea. The phylogenetic analyses confirmed that C. chanardi and C. kamolnorranathi are also nested within the C. siamensis species group, as previously hypothesized from morphology and color pattern characters.