A new species of Hemiphyllodactylus (Squamata, Gekkonidae) from Ha Giang Province, Vietnam.

An integrative analysis recovered a new species of the Hemiphyllodactylustypus group from a karst formation in Lung Cu Commune, Dong Van District, Ha Giang Province, northeastern Vietnam. Hemiphyllodactyluslungcuensissp. nov. is embedded within clade 6 of the typus group, bearing an uncorrected pairwise sequence divergence of 4.6-20.2% from all other species based on a 1,038 base pair segment of the mitochondrial NADH dehydrogenase subunit 2 gene (ND2). It is diagnosable from other species in clade 6 by statistically significant mean differences in normalized morphometric, meristic, and categorical characters. A multiple factor analysis using the three aforementioned character types recovered its unique, non-overlapping placement in morphospace as statistically significantly different from that of all other species in clade 6. The description of this new Hemiphyllodactylus species contributes to a growing body of literature underscoring the high degree of herpetological diversity and endemism in karst landscapes in Vietnam as well as in the genus Hemiphyllodactylus.

Two new species of Dixonius from Vietnam and Laos with a discussion of the taxonomy of Dixonius (Squamata, Gekkonidae).

Integrated analyses using maximum likelihood (ML), Bayesian inference (BI), principal component analysis (PCA), discriminate analysis of principal components (DAPC), multiple factor analysis (MFA), and analysis of variance (ANOVA) recovered two new diagnosable species of gekkonid lizards in the genus Dixonius, one from the Central Highlands, Gia Lai Province, Vietnam and another from the Vientiane Province, Laos. Phylogenetic analyses based on the mitochondrial NADH dehydrogenase subunit 2 gene (ND2) and adjacent tRNAs showed that Dixoniusgialaiensissp. nov. is the sister species of D.minhlei from Dong Nai Province, Vietnam and is nested within a clade that also includes the sister species D.siamensis and D.somchanhae. Dixoniusmuangfuangensissp. nov. is the sister species to D.lao from Khammouane Province, Laos and is embedded in a clade with D.vietnamensis, D.taoi, and undescribed species from Thailand. Multivariate (PCA, DAPC, and MFA) and univariate (ANOVA) analyses using combinations of 15 meristic (scale counts), six morphometric (measurements), and five categorical (color pattern and morphology) characters from 44 specimens encompassing all eight species of Dixonius from Vietnam and Laos clearly illustrate Dixoniusgialaiensissp. nov. and Dixoniusmuangfuangensissp. nov. are statistically different and discretely diagnosable from all closely related species of Dixonius. These integrative analyses also highlight additional taxonomic issues that remain unresolved within Dixonius and the need for additional studies. The discovery of these new species further emphasizes the underappreciated herpetological diversity of the genus Dixonius and illustrates the continued need for field work in these regions.

A new species of the genus Achalinus (Squamata: Xenodermidae) from Son La Province, Vietnam.

A new snake of the genus Achalinus Peters, 1869 is described based on an adult male specimen from Son La Province, Vietnam. Achalinus vanhoensis sp. nov. can be distinguished from its congeners by a combination of the following characters: 1) maxillary teeth 32; 2) suture between the internasals distinctly longer than that between the prefrontals; 3) loreal fused with prefrontal, prefrontals stretch towards the supralabials; 4) dorsal scales in 252323 rows, keeled; 5) supralabials six (left) and seven (right); 6) infralabials six; 7) temporals 2+2, the two anterior temporals in broad contact with eye; 8) ventrals 176; 9) subcaudals 84, entire; 10) cloacal entire; 11) dorsum in preservative dark purple grey above; 12) venter somewhat lighter with yellow-edged scales in the chin region, including infralabials; 13) posterior edges of ventrals and subcaudals with yellow margin. In the molecular analysis, the new species is recovered as a sister taxon of Achalinus timi, a species endemic to Vietnam, and genetically the two species are around 5% divergent from each other based on a fragment of the mitochondrial COI gene. This discovery brings the number of Achalinus species known from Vietnam to nine.

On the distribution of Gonyosoma prasinum (Blyth, 1854) and Gonyosoma coeruleum Liu, Hou, Ye Htet Lwin, Wang amp; Rao, 2021, with a note on the status of Gonyosoma gramineum Gnther, 1864 (Squamata: Serpentes: Colubridae).

Based on 85 examined specimens, photographs of living specimens and illustrations published in the literature, we refine the distribution ranges of both Gonyosoma prasinum (Blyth, 1854) and of the recently described species Gonyosoma coeruleum Liu, Hou, Ye Htet Lwin, Wang Rao, 2021, which was not clearly addressed in its original description. We also redescribe the syntypes of Coluber prasinus Blyth, 1854 and the holotype of Gonyosoma gramineum Gnther, 1864, we discuss the status of this latter taxon, and we describe the hemipenial morphology of G. coeruleum.

How many more species are out there? Current taxonomy substantially underestimates the diversity of bent-toed geckos (Gekkonidae, Cyrtodactylus) in Laos and Vietnam.

Cyrtodactylus is the most diverse genus of the family Gekkonidae and the world's third largest vertebrate genus. The number of species has increased more than fourfold over the last two decades. Indochina, especially Vietnam and Laos, has witnessed a surge in new species discoveries over the last three decades. The species number reported from Laos and Vietnam has remarkably increased from five in 1997 to 71 species in 2021. However, within the genus, several taxonomic issues have not yet been fully resolved. Based on recently collected samples from Laos and Vietnam, we conducted a comprehensive molecular review of Cyrtodactylus occurring in Laos and Vietnam. Our molecular analysis with support from morphological comparisons showed that C.thuongae is a junior synonym of C.dati and C.rufford is a junior synonym of C.lomyenensis. In total, 68 described species distributed in Laos and Vietnam are undisputed with strong support from both molecular and morphological evidence. On the other hand, the molecular analyses revealed that there are at least seven undescribed species in Vietnam and Laos, one in the C.angularis group, one in the C.chauquangensis, and five in the C.irregularis group. This number will likely increase significantly, as previous work suggested that the C.angularis and C.irregularis groups harbor three and six unnamed lineages, respectively. Based on survey gaps identified in our study, it is clear that additional new species will be discovered in poorly studied regions of central Vietnam and northern and southern Laos. As many species in the genus are facing high extinction risks, several undescribed populations might already be severely threatened by human activities in both countries. Therefore, urgent taxonomic research is needed before conservation assessments of newly discovered taxa can be undertaken to protect them from anthropogenic threats.

First record of the Cyrtodactylus brevipalmatus group (Squamata: Gekkonidae) from Vietnam with description of a new species.

A new species of the genus Cyrtodactylus is described from Dien Bien Province, northwestern Vietnam based on morphological and molecular data. Cyrtodactylus ngati sp. nov. can be distinguished from remaining congeners by the following combination of characters: maximum SVL 69.3 mm; dorsal pattern consisting of six dark irregular transverse bands between limb insertions; inter-supranasals one; dorsal tubercles present on occiput, body, hind limbs and on first half of tail; 1722 irregular dorsal tubercle rows at midbody; lateral folds clearly defined, with interspersed tubercles; 3238 ventral scales between ventrolateral folds; 13 precloacal pores separated by a diastema of 5/5 poreless scales from a series of 7/7 femoral pores in enlarged femoral scales; precloacal and femoral pores absent in females; 13 postcloacal tubercles on each side; transversely enlarged median subcaudal scales absent. In the molecular analyses, the new species is shown to be the sister taxon to C. interdigitalis from Thailand. This is the 47th species of the genus Cyrtodactylus and the first member of the C. brevipalmatus species group recorded from Vietnam.

A new species of Dixonius (Squamata: Gekkonidae) from Vientiane Capital, Laos.

A new species of the gekkonid genus Dixonius is described from Huaysorn-Huaysua village, Nasaithong District, Vientiane Capital, Laos. The new species can be distinguished from all other species by a combination of the following characters: maximum SVL 47.1 mm; 1921 longitudinal rows of dorsal tubercles at midbody; 2326 longitudinal rows of ventrals across the abdomen; 7 or 8 supralabials, 6 in mid-orbital position; 5 or 6 infralabials; 5 or 6 precloacal pores in males, femoral pores lacking; precloacal and femoral pores absent in females; a canthal stripe running from rostrum through the eye and terminating at back of head; dorsum brown with irregular dark marks. In phylogenetic analyses, the species is recovered as the sister taxon to D. siamensis, which occurs in Laos, Thailand, and Vietnam. Genetically, the two species are approximately 9.4% divergent from each other based on the complete mitochondrial ND2 gene with six partial or complete adjacent tRNAs. It is the 12th species known in the genus Dixonius and the second Dixonius species described from Laos.

A new species of the Gekko japonicus group (Squamata: Gekkonidae) from Khammouane Province, central Laos.

A new species of the Gekko (Japonigekko) japonicus group from Khammouane Province, central Laos is described based on morphological characters and molecular evidence. Morphologically, Gekko khunkhamensis sp. nov. can be distinguished from the remaining congeners by a combination of the following characters: size moderate (SVL 69.775.2 mm); nares in contact with rostral; internasals absent; postmentals enlarged; interorbital scales between anterior corners of the eyes 31 or 32; dorsal tubercles absent; ventrals between mental and cloacal slit 181185; midbody scales 127138; ventral scales 4245; subdigital lamellae on first toe 13 or 14, on fourth toe 14 or 15; tubercles on upper surface of fore and hind limbs absent; precloacal pores absent in the male and females; postcloacal tubercles 2; tubercles absent on dorsal surface of tail base; subcaudals distinctly enlarged; dorsal surface of body with five dark grey bands, which become irregular posteriorly. Genetically, the new species is placed in a clade, consisting of G. bonkowskii, G. nadenensis, G. scientiadventura, G. sengchanthavongi, and G. thakhekensis and differs from other congeners by at least 13% in terms of pairwise distance based on a fragment of the mitochondrial ND2 gene.

A new species of Achalinus (Squamata: Xenodermidae) from Trang An Landscape Complex, Ninh Binh Province, Vietnam.

We describe a new snake of the genus Achalinus based on an adult female specimen from Ninh Binh Province, Vietnam. Achalinus tranganensis sp. nov. is differentiated from its congeners genetically and by a unique combination of the following characters: 1) maxillary teeth 29; 2) suture between the internasals distinctly longer than that between the prefrontals; 3) loreal distinctly wider than high, extending from the nasal to the eye; 4) dorsal scales in 25-23-23 rows, keeled; 5) two pairs of prefrontals; 6) supralabials six; 7) infralabials six; 8) temporals 2+3, the two anterior temporals in contact with eye; 9) ventrals 171; 10) subcaudals 73+, unpaired; 11) cloacal plate entire; 12) dorsum in preservative reddish to greyish brown above; 13) the lower part of head side and chin region somewhat paler than the dorsum; 14) venter greyish cream, with the anterior region of each ventral and subcaudal somewhat darker. Based on molecular comparisons using a fragment of the mitochondrial cytochrome c oxidase subunit I (COI), the new species differs from other members of the genus by at least 11.8%. This discovery increases the number of Achalinus species known from Vietnam to seven.

Two new species of Cyrtodactylus (Squamata: Gekkonidae) from northern Laos, including new finding and expanded diagnosis of C. bansocensis.

Two new Cyrtodactylus species are described from Houaphan and Luang Prabang provinces in Laos based on morphological and molecular data. Cyrtodactylus houaphanensis sp. nov. differs from all other Cyrtodactylus in the C. wayakonei species group by at least 3.3 % genetic divergence in the COI gene and can be diagnosed in morphology as follows: SVL 75.8 mm; supralabials 9 or 10; infralabials 8 or 9; ventral scales 35; dorsal tubercles in 20 rows at midbody; precloacal pores 6 in the male; femoral pores absent; subcaudals enlarged; five irregular, brown bands between limb insertions. The new species morphologically resembles C. chauquangensis and revealed to be a sister taxon to C. puhuensis according to our genetic analyses, from which it mainly differs in the absence of enlarged femoral scales. Cyrtodactylus ngoiensis sp. nov. differs from other closely related congeners by at least 11.6 % genetic divergence in the COI gene and can be diagnosed in morphology as follows: maximum SVL 95.3 mm; supralabials 6-9; infralabials 8-11; ventral scales 38-43; dorsal tubercles in 15-21 rows at midbody; enlarged femoral scales present; precloacal pores 7 in the male, 7 pitted scales in females; femoral pores 14 in the male, absent in females; five bright yellowish transverse dorsal bands; subcaudals enlarged. The new species is shown to be a member of the C. wayakonei species group, but morphologically resembles C. dumnuii from Thailand. According to our phylogenetic analyses, it is a basal taxon to a clade comprising C. spelaeus, C. chauquangensis, C. vilaphongi, C. cucphuongensis, C. puhuensis, C. houaphanensis, C. otai and C. bobrovi. Based on a new record of C. bansocensis from central Laos, which represents the first recorded female we provide a redescription of C. bansocensis including expanded diagnosis. In addition, an updated identification key for the Cyrtodactylus known from Laos is provided.

A new species of Dixonius (Squamata: Gekkonidae) from the karst forest of Khammouane Province, central Laos.

A new species of Dixonius is described on the basis of three specimens from the karst forests around Thakhek town, Khammouane Province, Laos. The new species from Laos can be distinguished from other species of Dixonius based on molecular and morphological divergences. It is characterized by a maximum SVL of 55.4 mm; 20-23 longitudinal rows of dorsal tubercles at mid-body; 23-24 longitudinal rows of ventrals across the abdomen; 8-10 supralabials, 7 or 8 in mid-orbital position; 7 or 8 infralabials; 8 precloacal pores in male; the male without femoral pores; precloacal and femoral pores absent in females; uniformly pebble brown dorsum. In phylogenetic analyses, the new species is shown to be the sister taxon to two undescribed taxa from Thailand but differs by at least 8.6% in genetic pairwise distance from the latter based on the complete sequences of the mitochondrial ND2 gene with partial or complete sequences of six adjacent tRNAs. This is the ninth known species of Dixonius, and the second recorded species from Laos.

A new species of Lycodon Boie, 1826 (Serpentes: Colubridae) from Thanh Hoa Province, Vietnam.

We describe a new species of the genus Lycodon based on an adult male specimen from Thanh Hoa Province, Vietnam. Lycodon namdongensis sp. nov. is differentiated from its congeners by a combination of the following characters: dorsal scales in 17-17-15 rows, all smooth; supralabials 8; infralabials 10; one large loreal on each side, separated from the eye; cloacal single; ventral scales 218 (plus two preventral scales); subcaudals 85, paired; a total length of 723 mm; tail / total length ratio 0.205; dorsal head pattern whitish grey; dorsal surface of body with 23 narrow greyish cream bands; dorsal surface of tail with 14 cream bands; ventral surface of body mostly cream with a few small dark spots posteriorly; ventral surface of tail dark grey. Based on molecular comparisons, Lycodon namdongensis sp. nov. is recovered as a sister species to L. futsingensis with strong support values from all three analyses. The new species is at least 6.5% genetically divergent from other species within this clade as shown by a fragment of more than 1000 pbs of the mitochondrial cytochrome b. This discovery increases the number of Lycodon species known from Vietnam to 15.

A new species of Cyrtodactylus (Squamata: Gekkonidae) from Vientiane Province, northern Laos.

A new species of the genus Cyrtodactylus from Vientiane Province, northern Laos is described based on morphological and molecular data. Cyrtodactylus muangfuangensis sp. nov. can be distinguished from remaining congeners by the following combination of characters: maximum SVL 83.9 mm; dorsal pattern consisting of dark nuchal loop, nape band and five dark transversal bands between limb insertions; intersupranasals two; dorsal tubercles present on occiput, body, hind limbs and tail base; 15 or 16 irregular dorsal tubercle rows at midbody; lateral folds clearly defined, without interspersed tubercles; 31-37 ventral scales between ventrolateral folds; six precloacal pores and 15 femoral pores in males, which are interrupted by six to eight poreless scales; six precloacal pitted scales plus in total 10-15 pitted femoral scales in females, which are separated by six to eight poreless scales; enlarged precloacal and femoral scales present; two or three postcloacal tubercles; median subcaudal scales transversely enlarged. In molecular analyses, the new species is strongly supported as a member of the Cyrtodactylus phongnhakebangensis species group, and weakly corroborated as a sister taxon to C. pageli. Pairwise genetic comparison shows that it is at least 18% divergent from other congeners in the species group based on a fragment of the mitochondrial cytochrome C oxidase subunit I gene.

A new species of the Cyrtodactylus irregularis complex (Squamata: Gekkonidae) from Gia Lai Province, Central Highlands of Vietnam.

We describe a new species of the genus Cyrtodactylus from Gia Lai Province, Central Highlands of Vietnam based on morphological and molecular differences. Cyrtodactylus gialaiensis sp. nov. is differentiated from other congeners by a unique combination of the following characters: Size small, maximum known SVL reaching 62.8 mm; dorsal pattern consisting of six or seven dark transverse bands between limb insertions; intersupranasals two or three; dorsal tubercles at midbody in 16-21 irregular rows, strongly developed on flanks; lateral folds poorly defined with interspersed tubercles; ventral scales between ventrolateral folds 38-45; precloacal pores nine or 10 in males, eight pitted scales in the adult female, in a continuous row; femoral pores absent; enlarged femoral scales present; postcloacal tubercles two or three; dorsal tubercles present to half of tail; subcaudal scales not enlarged. In molecular analyses, the new species is weakly supported as a member of the Cyrtodactylus irregularis species group with a minimum pairwise genetic distance of 13.7% from others within the group.

A new karst dwelling species of the Gekko japonicus group (Squamata: Gekkonidae) from central Laos.

A new species of the Gekko japonicus group is described from Khammouane Province, central Laos, based on morphological characters and molecular data. Morphologically, Gekko nadenensis sp. nov. is differentiated from the remaining congeners by a combination of the following characters: size moderate (SVL 61.0-77.1 mm); nares bordered with rostral; internasals absent; postmentals enlarged; interorbital scales between anterior corners of the eyes 28-30; dorsal tubercles absent; ventral scales between mental and cloacal slit 175-185; midbody scale rows 123-140; ventral scale rows 38-40; subdigital lamellae on first toes 13-15, on fourth toes 14-16; finger and toe webbing present at base; tubercles on dorsal surface of fore and hind limbs absent; precloacal pores six (3+3 or 5+1) in a discontinuous row in males, absent in the female; postcloacal tubercles 1 or 2; tubercles absent on dorsal surface of tail base; subcaudals distinctly enlarged; dorsal surface of body with greyish brown blotches. Molecular analyses demonstrated the new species is closely related to G. bonkowskii and G. thakhekensis, but separated from them by approximately 7% in genetic divergence as shown by a fragment of the mitochondrial ND2 gene.

Cyrtodactylus rufford, a new cave-dwelling bent-toed gecko (Squamata: Gekkonidae) from Khammouane Province, central Laos.

We describe a new species of the gekkonid genus Cyrtodactylus from Khammouane Province, central Laos based on morphological and molecular data. Morphologically, Cyrtodactylus rufford sp. nov. differs from its congeners by a unique combination of the following characters: medium size, SVL reaching 72.5 mm; dorsal pattern with three or four light transverse bands between limb insertions; one intersupranasal; 14-16 irregular dorsal tubercle rows at midbody, weakly developed in the paravertebral region; 27-29 ventral scale rows between ventrolateral folds; 42-43 precloacal and femoral pores in a continuous row in males, enlarged femoral and precloacal scales present; 4 or 5 postcloacal tubercles on each side; dorsal tubercles present at base of tail; medial subcaudal scales enlarged. Molecular analyses show that the new species is closely related to C. khammouanensis, which was originally described from Khammouane Province.

A new species of karst-dwelling bent-toed gecko (Squamata: Gekkonidae) from Khammouane Province, central Laos.

We describe a new species of the genus Cyrtodactylus from Khammouane Province, central Laos based on morphological features and molecular data. Morphologically, Cyrtodactylus bansocensis sp. nov. is differentiated from other congeners by a unique combination of the following characters: medium size, SVL reaching 74.0 mm; dorsal pattern consisting of four light transverse bands between limb insertions; supranasals in contact with each other; dorsal tubercles at midbody in 14-15 irregular rows; lateral folds present without interspersed tubercles; ventral scales between ventrolateral folds 34-35; precloacal and femoral pores in males 34, separated by four poreless scales in the male holotype and in a continuous row in the male paratype; enlarged femoral and precloacal scales present; postcloacal tubercles 5-7 on each side; dorsal tubercles present at tail base; and subcaudal scales transversely enlarged. Molecular analyses revealed the new species to be closely related to Cyrtodactylus rufford, which is also found in Khammouane Province.

Evolution in karst massifs: Cryptic diversity among bent-toed geckos along the Truong Son Range with descriptions of three new species and one new country record from Laos.

Species designated as 'cryptic' share a similar morphotype, and are often only clearly separable by molecular data. Cyrtodactylus, the most diverse gecko genus of the family Gekkonidae, is a prime example, because many morphologically similar taxa have only recently been identified as new species as a result of available genetic evidence. However, while cryptic diversity of Cyrtodactylus is already well documented on the Vietnamese side of the Truong Son range, only scarce data is available from central Laos. In this study, we address this issue by means of an integrative approach, which employs morphological, molecular, and ecological data to distinguish cryptic species of the Cyrtodacylus phongnhakebangensis species group primarily distributed along the northern Truong Son Range. Our analyses based on 12 selected morphological characters, a partial mitochondrial gene (COI), and five ecological parameters revealed three undescribed cryptic Cyrtodactylus species from Hin Nam No National Protected Area, which are described as Cyrtodactylus calamei sp. nov., Cyrtodactylus hinnamnoensis sp. nov., and Cyrtodactylus sommerladi sp. nov. A fourth discovered Cyrtodactylus population in Hin Nam No proved to be the first country record of C. cryptus for Laos. Our results highlight the importance of applying an integrative approach to resolving the taxonomy of complex and cryptic species groups, and the role of the Truong Son Range in maintaining the high level of biodiversity over time.

A new species of Cyrtodactylus (Squamata: Gekkonidae) from the limestone forest of Khammouane Province, central Laos.

We describe a new species of the genus Cyrtodactylus on the basis of three specimens from Khammouane Province, Laos. Cyrtodactylus soudthichaki sp. nov. is distinguished from the remaining congeners by the combination of the following characters: adult SVL 69.2-70.0 mm; dorsal head and neck with dark blotches; nuchal loop present; dorsum with five brown bands between limb insertions; 19 or 20 irregular rows of dorsal tubercles; 32 or 33 ventral scale rows; ventrolateral folds present, with distinct tubercles; dorsal surface of hind limbs with tubercles; 29 precloacal and femoral pores in a continuous row in males, precloacal pores absent in the female; enlarged femoral and precloacal scales present; 4 or 5 postcloacal tubercles; and subcaudals transversely enlarged. The new species most closely resembles Cyrtodactylus jaegeri and Cyrtodactylus roesleri in overall coloration and pattern. However, they can be clearly distinguished from each other in the number of dorsal tubercle rows, ventral scales, and femoral and precloacal pores. Cyrtodactylus soudthichaki is the 16th species of Cyrtodactylus known from Laos.

Morphological and molecular review of the Gekko diversity of Laos with descriptions of three new species.

A review of the taxonomy, phylogeny, zoogeography, and ecology of the genus Gekko in Laos is provided based on morphological and molecular datasets. Three new species, which are both morphologically distinctive and molecularly divergent from described congeners, are described from Khammouane Province, central Laos: two members of the G. japonicus group, Gekko bonkowskii sp. nov. and Gekko sengchanthavongi sp. nov., and another member of the G. petricolus group, Gekko boehmei sp. nov. Gekko bonkowskii sp. nov. is closely related to the recently described G. thakekensis, which also occurs in Khammouane Province. Gekko sengchanthavongi sp. nov. is supported as a sister taxon to G. scientiadventura and Gekko boehmei sp. nov. is recovered as a sister species to G. petricolus. In addition, a key to the currently recognized members of the genus Gekko from Laos is provided.