Ongoing declines for the world's amphibians in the face of emerging threats.

Systematic assessments of species extinction risk at regular intervals are necessary for informing conservation action1,2. Ongoing developments in taxonomy, threatening processes and research further underscore the need for reassessment3,4. Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize immediate conservation action, scaled-up investment is urgently needed to reverse the current trends.

Two new karst-adapted species in the Cyrtodactyluspulchellus group (Reptilia, Gekkonidae) from southern Thailand.

The exploration of unsurveyed areas in southern Thailand discovered two new karst-adapted species, Cyrtodactylussungaiupesp. nov. and Cyrtodactyluswangkhramensissp. nov., from Thung Wa and La-ngu Districts, Satun Province, respectively. These new species are members of the C.pulchellus group that occur along the Thai-Malay Peninsula. The new species can be distinguished from all other congeners by their key morphological characters and genetic divergence. Morphologically, Cyrtodactylussungaiupesp. nov. and Cyrtodactyluswangkhramensissp. nov. can be diagnosed from other members by having a combination of differences in body size; degree of dorsal tuberculation; absence of tubercles on ventral surfaces; number of ventral scales, paravertebral tubercles and femoroprecloacal pores in males only; deep precloacal groove only in males; absence of a scattered pattern of white dorsal tubercles; number of dark body bands; and the extent of caudal tubercles on an original tail. Although the two species are sister taxa and have nearly identical morphologies, they are considered to be different species, based on a relatively high uncorrected pairwise genetic divergence of the mitochondrial ND2 gene (6.59-6.89%), statistically significant univariate and multivariate morphological differences (PERMANOVA and ANOVA) and diagnostic characteristics of caudal tuberculation on the original tail. Moreover, Cyrtodactylussungaiupesp. nov. and Cyrtodactyluswangkhramensissp. nov. are currently restricted to their karstic type localities which may serve as a geographic barrier to dispersal and gene flow.

Comments on the taxonomic status of Cyrtodactylus zebraicus Taylor, 1962 (Squamata: Gekkonidae) from Northern Peninsular Malaysia.

The taxonomic status of Cyrtodactylus zebraicus in Peninsular Malaysia has been plagued with uncertainty over the last three decades owing to a lack of vouchered material. Recent collections confirmed the presence of this species in the northernmost state of Perlis and for the country. An expanded description of the newly collected Peninsular Malaysian specimens as well as the holotype of C. zebraicus is provided along with a comparison with other Cyrtodactylus species in the country. This study adds to the growing number of herpetofaunal species with Indo-Burmese affinities discovered in northern states of the country and the biogeographic importance of this region for the exchange of fauna and flora. The findings also highlight the importance of continued field work along the biogeographic interchange of the Banjaran Nakawan that separates southwestern Thailand from northwestern Peninsular Malaysia and the need to sample and collect voucher specimens that can be deposited in proper scientific collections for current and future research.

A new species of the Cyrtodactylusbrevipalmatus group (Squamata, Gekkonidae) from the uplands of western Thailand.

An integrative systematic analysis recovered a new species of the Cyrtodactylusbrevipalmatus group from the uplands of Thong Pha Phum National Park, Kanchanaburi Province in western Thailand. Cyrtodactylusthongphaphumensissp. nov. is deeply embedded within the brevipalmatus group, bearing an uncorrected pairwise sequence divergence of 7.6-22.3% from all other species based on a 1,386 base pair segment of the mitochondrial NADH dehydrogenase subunit 2 gene (ND2) and adjacent tRNAs. It is diagnosable from all other species in the brevipalmatus group by statistically significant mean differences in meristic and normalized morphometric characters as well as differences in categorical morphology. A multiple factor analysis recovered its unique and non-overlapping placement in morphospace as statistically significantly different from that of all other species in the brevipalmatus group. The description of this new species contributes to a growing body of literature underscoring the high degree of herpetological diversity and endemism across the sky-island archipelagos of upland montane tropical forest habitats in Thailand, which like all other upland tropical landscapes, are becoming some of the most imperiled ecosystems on the planet.

Hidden diversity of rock geckos within the Cnemaspissiamensis species group (Gekkonidae, Squamata): genetic and morphological data from southern Thailand reveal two new insular species and verify the phylogenetic affinities of C.chanardi and C.kamolnorranathi.

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 Cnemaspissiamensis species group. Cnemaspissamui 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 4th 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. Cnemaspissimilan 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 4th 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. Cnemaspissamui sp. nov. is found along granitic rocky stream outcrops of Hin Lad Waterfall, Ko Samui, Gulf of Thailand, while Cnemaspissimilan 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.

A new species in the Cyrtodactylusoldhami group (Squamata, Gekkonidae) from Kanchanaburi Province, western Thailand.

Cyrtodactylusmonilatus 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%. Cyrtodactylusmonilatus 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.

Integrative taxonomy delimits and diagnoses cryptic arboreal species of the Cyrtodactylusbrevipalmatus group (Squamata, Gekkonidae) with descriptions of four new species from Thailand.

Species delimitation and species diagnosis must remain separate operations to avoid constructing taxonomies comprised of non-monophyletic species based on morphological similarity as opposed to phylogenetic propinquity. This is particularly true for highly specialized species such as the range-restricted upland taxa in the Cyrtodactylusbrevipalmatus group of Indochina where strong selection pressure for an arboreal lifestyle has contributed to morphologically similar but distantly related species. This in turn, has resulted in a history of erroneous taxonomies that have actually obscured rather than revealed the diversity within this group. A Bayesian phylogeny of the C.brevipalmatus group recovered at least 15 putative species-level lineages, at least seven of which are undescribed, and of which four are described herein. A total evidence morphological data set comprised of 16 normalized morphometric, 15 meristic, and seven categorical characters scored across 51 individuals was subjected to a multiple factor analysis (MFA) and an analysis of variance (ANOVA) to diagnose the putative species. These new species descriptions contribute to focusing attention to the unrealized diversity in upland tropical ecosystems, which due to climate change, are some of the most impearled ecosystems on the planet. Thus, it is paramount that taxonomies do not conflate species identities and underrepresent true diversity.

A new insular species of the Cyrtodactyluspulchellus group (Reptilia, Gekkonidae) from Tarutao Island, southern Thailand revealed by morphological and genetic evidence.

The bent-toed geckos of the Cyrtodactyluspulchellus group are widely distributed along the Thai-Malay Peninsula. Although taxonomic and phylogenetic studies of this species group have been continuously conducted, only some populations from Thailand have been included, resulting in hidden diversity within this group. In this study, we used morphological and molecular data to clarify the taxonomic status and describe a new population from Tarutao Island, Satun Province, southern Thailand. Cyrtodactylusstellatus sp. nov. can be distinguished from its congeners by the combination of the following morphological characters: body size; tuberculation; number of dark body bands, ventral scales, and femoroprecloacal pores in males; presence of precloacal pores in females; and scattered pattern on dorsum. Phylogenetic analyses of the mitochondrial ND2 gene recovered the new species as the sister species to C.astrum, with an uncorrected pairwise divergence of 9.78-12.37%. Cyrtodactylusstellatus sp. nov. is currently only known from Tarutao Island, Thailand. The discovery of this species suggests that the diversity within the C.pulchellus group remains underestimated and future exploration of unsurveyed areas are needed to further the understanding of this group and its geographic range.

Taxonomic reassessment and phylogenetic placement of Cyrtodactylus phuketensis (Reptilia, Gekkonidae) based on morphological and molecular evidence.

The taxonomy and phylogeny of the Cyrtodactylus pulchellus complex along the Thai-Malay Peninsular region has been the focus of many recent studies and has resulted in the recognition of 17 species. However, the majority of these studies were focused on Peninsular and insular Malaysia where there were specimens and genetic vouchers. The taxonomic status and phylogenetic relationships of the Thai species in this complex remain unresolved, due to the lack of genetic material of some species, especially C. phuketensis and C. macrotuberculatus from Thai populations. In this study, we investigated the phylogenetic relationship between C. phuketensis and its closely related species C. macrotuberculatus, using both morphometric and molecular data. Phylogenetic analyses of mitochondrial NADH dehydrogenase subunit 2 (ND2) gene revealed that C. phuketensis is embedded within a C. macrotuberculatus clade with 1.45-4.20% (mean 2.63%) uncorrected pairwise sequence divergences. Morphological comparisons showed nearly identical measurements of C. phuketensis and C. macrotuberculatus and overlapping ranges in meristic characters. Based on these data, C. phuketensis is considered to be a variant of C. macrotuberculatus, thus rendering C. phuketensis a junior synonym of C. macrotuberculatus.

A new skink of the genus emSubdoluseps/em Freitas, Datta-Roy, Karanth, Grismer amp; Siler, 2019 (Squamata: Scincidae) from southern Vietnam.

We describe a new species of the genus Subdoluseps Freitas, Datta-Roy, Karanth, Grismer Siler from a coastal area in southern Vietnam. Subdoluseps vietnamensis sp. nov. is characterized by the following morphological characters: medium size in adults (snout-vent length up to 48.7 mm); tail length/snout-vent length ratio 1.04; toes not reaching finger when limbs adpressed; 27-30 midbody scale rows, smooth; 55-57 paravertebral scales; 55-62 ventral scale rows; 64-74 subcaudal scales; frontoparietal scale single; four supraoculars; prefrontals not in contact with one another; two loreal scales; seven supralabials; ear-opening with two lobules on the anterior border; smooth lamellae beneath finger III 9 or 10 and toe IV 12-15; six enlarged precloacal scales; and four distinct black stripes on dorsum. The new species differs genetically from its closest congeners, S. bowringii (Günther) and S. frontoparietale (Taylor), by uncorrected p-distances of 10.0% and 9.5%, respectively in ND1 sequences, and clusters into the same matriline with these two congeners on the phylogenetic trees.

A New Limnonectes (Anura: Dicroglossidae) from Southern Thailand.

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.

A new species of Cyrtodactylus Gray (Squamata; Gekkonidae) from the Thai Highlands with a discussion on the evolution of habitat preference.

A new gekkonid lizard, Cyrtodactylus maelanoi sp. nov., from Mae Hong Son Province of the Thai Highlands is described using an integrative taxonomic analysis based on morphology, color pattern, and the mitochondrial gene NADH dehydrogenase subunit 2 (ND2) and its flanking tRNAs. Phylogenetic analyses place the new species within clade 1 of the C. sinyineensis group and as the sister species to C. inthanon with an uncorrected pairwise sequence divergence of 3.9%. Collection data gathered in the field indicate that C. maelanoi sp. nov. is a habitat generalist. Reconstruction of the ancestral habitat preference for the C. sinyineensis group by way of stochasitc character mapping (SCM) indicates that karstic environments were the ancestral condition out of which the general habitat preference of the ancestor of C. maelanoi sp. nov. and C. inthanon and that of C. amphipetreaus and C. doisuthep evolved three times independently. Additionally, SCM demonstrated that the evolution of a granitic habitat preference from a karst-adapted ancestor happened in C. aequalis. The discovery of a new upland species in the Thai Highlands brings into focus the understudied nature of the mountain systems of western Thailand and the need for their continued exploration and conservation.

Integrative taxonomy of the rock-dwelling gecko Cnemaspis siamensis complex (Squamata, Gekkonidae) reveals a new species from Nakhon Si Thammarat Province, southern Thailand.

The rock-dwelling gecko genus Cnemaspis is one of the most species-diverse genera of gekkonid in Thailand. Earlier studies relied on morphological data to identify species, but cryptic morphology often obscured species diversity in Cnemaspis. In this study, an integrative taxonomic approach based on morphological characters and sequences of the mitochondrial NADH dehydrogenase subunit 2 (ND2) gene were used to clarify current taxonomy of the Cnemaspis siamensis complex and delimit a new species from Lan Saka District, Nakhon Si Thammarat Province, southern Thailand. Cnemaspis lineatubercularis sp. nov. is distinguished from other congeneric species by the combination of morphological characters: (1) maximum snout-vent length (SVL) of 40.6 mm (mean 38.8 ± SD 1.4, N = 12) in adult males and maximum SVL of 41.8 mm (mean 39.5 ± SD 1.9, N = 7) in adult females; (2) 8-9 supralabial and infralabial scales; (3) gular, pectoral, abdominal, and subcaudal scales keeled; (4) rostral, interorbitals, supercilium, palmar scales, and ventral scales of brachia smooth; (5) 5-6 small, subconical spine-like tubercles present on flanks; (6) 19-21 paravertebral tubercles linearly arranged; (7) 27-29 subdigital lamellae under the fourth toe; (8) 4-7 pore-bearing precloacal scales, pores rounded arranged in chevron shape and separated only in males; (9) one postcloacal tubercles each side in males; (10) ventrolateral caudal tubercles present anteriorly; (11) caudal tubercles restricted to a single paravertebral row on each side; (12) single median row of subcaudal scales keeled and lacking enlarged median row; and (13) gular region, abdomen, limbs and subcaudal region yellowish only in males. Genetically, the uncorrected pairwise divergences between the new species and their congeners in the C. siamensis group were between 15.53-28.09%. The new species is currently known only from granitic rocky streams at Wang Mai Pak Waterfall in the Nakhon Si Thammarat mountain range. Its discovery suggests that additional unrecognized species of Cnemaspis may still occur in unexplored areas of southern Thailand.

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.

Corrigenda: Species delimitation of crab-eating frogs (Fejervarya cancrivora complex) clarifies taxonomy and geographic distributions in mainland Southeast Asia. ZooKeys 883: 119-153. https://doi.org/10.3897/zookeys.883.37544.

[This corrects the article DOI: 10.3897/zookeys.883.37544.].

Species delimitation of crab-eating frogs (Fejervarya cancrivora complex) clarifies taxonomy and geographic distributions in mainland Southeast Asia.

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.

Population demography of Oldham's leaf turtle (Cyclemys oldhamii) in protected and disturbed habitats in Thailand.

BACKGROUND: Freshwater turtle populations are vulnerable to a range of human activities because of particular life history attributes, and anthropogenic impacts can cause shifts in demographic traits, including survival, density and population structure. Asian freshwater turtles have undergone dramatic population declines in recent decades principally because of collection for food, pet, and traditional medicine markets. Despite this, few studies have been conducted on the population demography of these turtles, thereby limiting our understanding of population trends and the development of conservation actions. Oldham's leaf turtle (Cyclemys oldhamii) is one of the most commonly traded turtles in Asian markets, but previous published studies have focused solely on systematics. METHODS: We conducted a mark-recapture study of C. oldhamii at three sites in northeastern Thailand-a protected stream, a degraded stream, and human-constructed ponds-and evaluated differences in survival, density, population structure, and sexual dimorphism among sites. RESULTS: We captured 77 turtles at the protected stream, 67 at the constructed ponds, and two in the degraded stream. Survival was 12% lower and density was 35% lower in the constructed ponds than in the protected stream. Size class structure was skewed toward smaller individuals at the constructed ponds, and both sites exhibited subadult-skewed age class structure. Sex ratios were not statistically different than 1:1 at either site and did not differ between sites. We did not document sexual dimorphism in either population. DISCUSSION: Explanations for lower survival, lower densities, and skewed size class structure at the constructed ponds include collection for consumption or Buddhist prayer release locally, collection for illegal export from Thailand, predation by domestic dogs associated with humans living nearby, or lower habitat quality. Evidence from our study suggests that collection, either for local use or export, is the most likely explanation for differences in demographic characteristics between the two sites. The information gained from this study may contribute to a status assessment for C. oldhamii and development of conservation actions should they become necessary to protect populations in Thailand.

Six new species of the Cyrtodactylus intermedius complex (Squamata: Gekkonidae) from the Cardamom Mountains and associated highlands of Southeast Asia.

An integrative taxonomic analysis using color pattern, morphology, and 1449 base pairs of the ND2 mitochondrial gene and its five flanking tRNAs demonstrated that eight species-level lineages occur within the Cyrtodactylus intermedius complex (Cyrtodactylus intermedius sensu stricto, C. phuquocensis and related populations) of the Cardamom mountains and associated highlands that have a sequence divergence ranging 3.4-8.9%. Additionally, each lineage is discretely diagnosable from one another based on morphology and color pattern and most occur in specific geographic regions (upland areas, karst formations or islands) that prevent or greatly restrict interpopulation gene flow. Six of these lineages were masquerading under the nomen C. intermedius and are described as the following: Cyrtodactylus auralensis sp. nov. endemic to Phnom Aural, the highest mountain in Cambodia; C. bokorensis sp. nov. endemic to the Bokor Plateau, Cambodia; C. cardamomensis sp. nov. from the main block of the Cardamom mountains; C. thylacodactylus sp. nov. endemic to Phnom Dalai the northernmost peak of the Cardamom mountains; C. laangensis sp. nov. endemic to the Phnom Laang karst formation, Cambodia; and C. septimontium sp. nov. from the Bay Núi Hills of southwest Vietnam.

A new Limnonectes (Anura: Dicroglossidae) from southern Laos.

A new species of "fanged frog" in the genus Limnonectes resembling L. kohchangae (Smith, 1922) from southeastern Thailand and southwestern Cambodia is described from upper elevations of the Bolaven Plateau, southern Laos. However, the new species, L. coffeatus sp. nov., is not resolved to be the closest relative of L. kohchangae, and is further distinguished from this taxon by differences in skin texture and coloration. The new species is potentially threatened from extensive conversion of forest into coffee plantations on the Bolaven Plateau.