Ventral Scales Research Articles

Integrative Taxonomy Revealed High Diversity of Hemiphyllodactylus Bleeker, 1860 (Squamata: Gekkonidae) and the Description of Three New Species from Yunnan Province, China.

The karst landform in Yunnan Province, China, represents one of the most biodiverse regions for Hemiphyllodactylus. Previous research has revealed that the karst forests in this province host a greater diversity of Hemiphyllodactylus than previously acknowledged. However, substantial fundamental data essential for taxonomic and biogeographical studies are lacking. We conducted extensive surveys for Hemiphyllodactylus in the Yunnan Province that led to the discovery of three new species from Menglian Dai, Lahu, and Wa Autonomous County and Jinghong City based on morphological and genetic data. A phylogenetic reconstruction based on the ND2 gene (1038 bp) placed the three new species into clade 3 and clade 4 of Agung et al. The uncorrected genetic pairwise distance of the Menglian specimens were greater than 5.7%, and those of the Jinghong City specimens were greater than 5.2% and 8.5%, respectively. They could be distinguished from their congeners by body size, chin scales, internasal scales, ventral scales, dorsal scales, and the total number of femoral and precloacal pores. Furthermore, we update the distributional knowledge of the known species.

Effect of Surface Morphology and Internal Structure on the Tribological Behaviors of Snake Scales from Dinodon rufozonatum.

Snakes can move freely on land, in lakes, and in other environments. During movement, the scales are in long-term contact with the external environment, providing protection to the body. In this study, we evaluated the mechanical properties and scratching performance of the ventral and dorsal scales from Dinodon rufozonatum, a generalist species that moves on both land and in streams under wet and dry conditions. The results showed that the elastic modulus and hardness of the dry scales were greater than those of the wet scales. The average scale friction coefficient under wet conditions (0.1588) was 9.3% greater than that under dry conditions (0.1453). The scales exhibit brittle damage in dry environments, while in wet environments, ductile damage is observed. This adaptation mechanism allows the scales to protect the body by dissipating energy and reducing stress concentration, ensuring efficient locomotion and durability in both terrestrial and aquatic environments. Understanding how this biomaterial adapts to environmental changes can inspire the development of bionic materials.

Morphological characterization and sexual dimorphism of saw-scaled viper (<em>Echis</em>: viperidae: ophidia) population in Sri Lanka

The Saw-scaled vipers (SSV) of the genus Echis (Viperidae: Ophidia) primarily inhabit tropics. In Sri Lanka, E. carinatus is densely populated in the Northern Province where they account for over 50% of the local snakebites. Although it was initially reported as a unique Sri Lankan subspecies named E. c. sinhaleyus, its existence was later questioned, urging the need for more detail studies. The present study examined morphological characters and sexual dimorphism in 30 specimens (17 males and 13 females) collected from Kilinochchi and Jaffna Districts in the Northern Province, using 12 mensural and 17 meristic traits, updating Deraniyagala’s report of 1951. Results showed that the adult females have longer snout to vent length (SVL) than that of males (280.34±43.32 vs. 240.88±27.03), revealing a positive sexual dimorphism index. Males had a greater TL/SVL ratio (x̄̄=13.89±0.68) than that of females (x̄̄=10.65±085). ANCOVA test retrieved most accurate and an independent significant effect of ‘sex’ on TL while SVL serving as the covariate. Males and females shared consistent meristic characters, except for number of dorsal scales at the lower part of the body, ventral and sub-caudal scales. There were more ventral scales in females (145.54±3.31) than that of males (138.41±4.08), and sub-caudal scales were higher in number in males (28.94±1.85) than that of females (25.85±2.82). Although, there were some colour pattern variations of the specimens, (head pattern and ventral pattern), they were not sex-associated and distributed evenly between males and females. This is the first study to illustrate the detail morphometric characters; mensural traits; meristic traits, and color patterns and to demonstrate the sexual dimorphism in the SSV from Sri Lanka, with noticeable differences in the snoutvent length (SVL), tail length (TL), ventral scales, and sub-caudal scales between male and female.

Armed on the back: Hidden biomineralized scales in the ventral girdle of chiton Acanthopleura loochooana

Flexible protective armors are found in large animals such as fish skins, snake skins, and pangolin scales. For small-sized invertebrates, such armors are paid less attention and overlooked. Chitons, a type of marine mollusk, possess mineralized armors covering the whole dorsal body. The dorsal scales in the girdle tissue are well known, in this study, we reported hidden mineralized scales in the ventral side of chiton Acanthopleura loochooana girdles for the first time. The ventral surface is covered with scales with ca. 40 μm in length, forming continuous but overlapped scales. Additionally, scales are formed from aragonitic spicule-like and square-like scales, embedded in the cuticle layer. Nanoindentation testing results showed that the hardness and elastic modulus of ventral scales were ∼20 % higher compared to those in the dorsal scales, exhibiting good hardness and wear resistance. The combination of the ventral scales and cuticle, along with the regular arrangement of ventral scales, may allow chitons to simultaneously address complex and variable attachment interfaces while also providing wear-resistant protection. This study provides insights for designing protective structures that balance flexibility and durability. Statement of significanceBiomineralization is universal in nature and provides protection and support for animals. However, mineralization of dermal skin is not commonly seen. Herein, for the first time, we reported hidden minerals covering the whole ventral side of skin in a small marine animal, chitons. Calcium carbonate minerals are arranged regularly and manifest different morphology in different regions. Additionally, these minerals are embedded in a continuous cuticle layer covering the whole animal. The material also indicates a higher wear-resistant property. This study extends our understanding of the diverse functionality of biominerals and provides a prototype for designing wear-resistant materials.

A New Species of Cyrtodactylus tibetanus Group (Reptilia: Squamata: Gekkonidae) from Xizang Autonomous Region, China.

A new Cyrtodactylus species, C. laevissp. nov., from the dry-hot valleys near the Yarlung Zangbo River in Re Village, Jindong Countryside, Lang County, Linzhi City, Xizang Autonomous Region, China, is described herein based upon the integrative taxonomic results combining molecular phylogenetic systematics and morphological characteristic comparisons. Our molecular phylogeny was inferred by combining three mitochondrial gene fragments (16S/CO1/ND2), and it indicated a distinct differentiation between the new species and C. tibetanus species complex, with obvious genetic distances (16S 9.9-11.8%/CO1 16.5-18.2%/ND2 16.6-18.5%) detected, supporting its validity. Morphologically, the new species can be easily distinguished from its congers by the following characters: (1) medium size (SVL 48.58-50.92 mm), (2) tubercles on dorsum sparse, (3) tail segments absent and tubercles on tails absent, (4) supralabials 10-12 and infralabials 8-10, (5) interorbital scales between anterior corners of the eyes 28-32, (6) scale rows at midbody 96-98, (7) ventral scales between mental and cloacal slit 145-153, (8) ventral scale rows 41-45, and (9) 4 to 5 white-yellow transverse bands with brown dots and black merges between the nape and sacrum. The description of C. laevissp. nov. increased the total species number of C. tibetanus group to three, and the total Cyrtodactylus species number in Xizang to six and in China to eleven. The new species is currently only known from the type locality with its extremely small populations and needs future surveys to reveal its distribution range, population status, natural history, and mechanisms so that the new species can coexist with Altiphylax medogense.

A New Species of the Genus Tropidophorus Duméril, Bibron, 1839 (Reptilia: Squamata: Scincidae) from China-Vietnam Border Region in Southeastern Yunnan Province, China

Based on morphological and genetic data, we describe a new species of Tropidophorus from the tropical karst landscape in southeastern Yunnan Province, China, close to the Vietnam border. Phylogenetically, the new species forms a clade with T. baviensis, T. murphyi, and T. hainanus, with p-distances ranging from 4.7–5.1% for the 16S gene and 3.9–6.8% for 12S gene. Morphologically, the new species shares the karst morphotype of Tropidophorus, particularly similar as T. murphyi and T. baviensis, in which all having a dorsally compressed head and body, smooth dorsal head scales, and distinctively keeled body scales. However, the new species can be distinguished from these similar species by numbers of supralabial scales, ventral scales, scales around the tail at the10th subcaudal, and a larger body size. We emphasize the urgency of conservation for the tropical karst landscape in northern Indochina.

A new species of Uropeltis Cuvier, 1829 (Serpentes: Uropeltidae) from the eastern escarpment of the southern Western Ghats, India

A new species of the uropeltid (‘shieldtail’) snake genus Uropeltis is described based on eight specimens from the southern part of peninsular India’s Western Ghats. Uropeltis caudomaculata sp. nov. is phenotypically and genetically most similar to U. pulneyensis (Beddome, 1863), but differs primarily in having more ventral scales and in being restricted to the eastern escarpment of the Western Ghats between Meghamalai and approximately 15 km East of Munnar rather than in the Palani Hills, as well as differing in DNA nucleotide sequences. From verified records, we consider U. pulneyensis to be known thus far only from the Palani Hills, and we designate a lectotype for the species. Reconsideration of the holotype of Silybura guentheri Beddome, 1878 from Meghamalai leads us to conclude that it should be removed from the subjective junior synonymy of U. pulneyensis and be considered a distinct though very poorly known species, Uropeltis guentheri comb. nov.

Decoupled evolution of ventral and dorsal scales in agamid lizards: ventral keels are associated with arboreality.

Arboreality has evolved in all major vertebrate lineages and is often associated with morphological adaptations and increased diversification concomitant with accessing novel niche space. In squamate reptiles, foot, claw, and tail morphology are well-studied adaptations shown to be associated with transitions to arboreality. Here, we examined a less well understood trait-the keeled scale-in relation to microhabitat, climate, and diversification dynamics across a diverse lizard radiation, Agamidae. We found that the ancestral agamid had keeled dorsal but not ventral scales; further, dorsal and ventral keels are evolutionarily decoupled. Ventral keeled scales evolved repeatedly in association with arboreality and may be advantageous in reducing wear or by promoting interlocking when climbing. We did not find an association between keeled scales and diversification, suggesting keels do not allow finer-scale microhabitat partitioning observed in other arboreal-associated traits. We additionally found a relationship between keeled ventral scales and precipitation in terrestrial species where we posit that the keels may function to reduce scale degradation. Our results suggest that keeled ventral scales facilitated transitions to arboreality across agamid lizards, and highlight a need for future studies that explore their biomechanical function in relation to microhabitat and climate.

A new species of green pitviper of the Trimeresurus macrops complex (Reptilia: Serpentes: Viperidae) from South Central Coastal Region of Vietnam

We describe a new species of green pitviper from southern and central parts of coastal Vietnam based on morphological and molecular (2406 bp from cyt b, ND4, and 16S rRNA mitochondrial DNA genes) lines of evidence. Trimeresurus cyanolabris sp. nov. is distinguished from its congeners by the combination of the following morphological characters: small size, maximum known SVL of 638 mm; dorsal scales in 21 (rarely 23)–21–15 rows, moderately keeled except the outermost rows; ventral scales 166–178; subcaudal scales 52–75, all paired; hemipenis forked, calyculate, reaching the 8th subcaudal; eye bright yellow in both sexes; dorsal surface deep green lacking cross-bands; postocular white stripe missing in both sexes; ventrolateral stripe faintly present on the first few dorsal scale rows in males, absent in females; throat, chin, and lower labials in shades of blue. The new species forms a distinct clade on the phylogenetic tree of the genus Trimeresurus and differs from the morphologically similar T. rubeus by a significant divergence in cytochrome b mitochondrial DNA gene sequences (p = 6.0%). The new species is currently known from low- to mid-elevations (ca. 90–400 m a.s.l.) in tropical forests of central-southern Vietnam. This discovery further underlines the importance of this area as a local center of herpetofaunal diversity and endemism, which is under great threat of deforestation.

Are Bergmann's and Jordan's rules valid for a neotropical pitviper?

AbstractMorphological variation along the spatial distribution of species has been extensively investigated in ecological studies, and several ecogeographical rules explore the relationships between morphological traits and the environment. Many morphological traits are correlated, providing an opportunity to evaluate the validity of multiple ecogeographical rules simultaneously. Bergmann's rule predicts that endothermic animals in colder locations are larger than those in warmer locations. Jordan's rule predicts that fish from colder locations have more vertebrae than those from warmer locations. We tested the validity of Bergmann's and Jordan's rules for the neotropical lancehead snake Bothrops jararaca. We evaluated three morphological characters of 342 specimens: number of ventral scales (proxy for vertebrae number), snout–vent length (a linear measure of body size) and stoutness (volumetric body size). We implemented spatial regressions to evaluate the variation of morphological dimensions using climatic predictors: the minimum temperature and evapotranspiration. SVL was poorly related to minimum temperature and evapotranspiration. However, stouter individuals were found in colder places with greater evapotranspiration, following Bergmann's rule and the water conservation hypothesis. Individuals in warmer locations also had a greater number of ventral scales, reversing Jordan's rule. We showed that different selective pressures act on different morphological dimensions. Although stoutness follows Bergmann's rule, its variation would arise from an energy storage demand rather than heat conservation. Also, stoutness variation along evapotranspiration gradients could represent a mechanism to avoid hydric stress in environments with considerable climatic variations. The variation in vertebrae number along temperature gradients could be related to ecological factors and foraging. We highlight that physioecological mechanisms to deal with climatic variation and ecological aspects could be identified in snakes through intraspecific analyses, contrasting with interspecific studies that can hardly detect general trends. Due to different environmental effects on body size, we shed new light on the importance of exploring multiple morphological dimensions in macroecological studies.

Two new species of the shieldtail snake genus Rhinophis Hemprich, 1820 (Serpentes: Uropeltidae), from the Rakwana and the Knuckles Massifs of Sri Lanka

Two new species of the uropeltid snake genus Rhinophis Hemprich, 1820 are described from Sri Lanka. Rhinophis martin sp. nov. is described from 11 type specimens from the Rakwana Massif, and another 22 specimens from the same region are referred to this new species. Rhinophis dinarzardae sp. nov. is described from eight type specimens from the Knuckles Massif, and another 64 specimens from the Knuckles and adjacent hills are referred to this new species. Rhinophis martin sp. nov. has apparently not been reported previously under any scientific name, but is distinct in scalation, colour pattern and DNA. Rhinophis dinarzardae sp. nov. has long-been confused with the superficially similar R. philippinus, from which it differs by having more ventral scales, by occurring in the northern part of the Knuckles Massif and adjacent hills to the West rather than in the Central Highlands upland region (and possibly areas to the South and West) of Sri Lanka, and in DNA sequence data. The new descriptions take the inventory of currently recognised, named uropeltid species in Sri Lanka to 20, all members of the genus Rhinophis.

Another new micro-endemic, limestone-dwelling leaf-toed gecko (Gekkonidae: Dixonius) from Phetchaburi Province, western Thailand

We describe Dixonius chotjuckdikuli sp. nov. from Khao Ebid (Mount Ibit), Khao Yoi District, Phetchaburi Province, western Thailand. The new, limestone-dwelling species differs from all currently recognized species of Dixonius by the following combination of morphological characters and pattern: maximal known snout-vent length of 45.6 mm, 18 (rarely 16) longitudinal rows of dorsal tubercles; 31 to 34 paravertebral scales; 18 (rarely 16) longitudinal rows of ventral scales across the abdomen; 20 to 22 interciliary scales; 5 or 6 precloacal pores in males, no pores in females; a marked canthal stripe extending beyond the shoulder; and a blotched dorsal pattern in males, females and juveniles. This description brings the number of Dixonius species to 17, among which seven species are endemic to Thailand.

A new species of karst-associated kukri snake (Reptilia: Squamata: Colubridae: Oligodon Fitzinger, 1826) from southern Thailand

Abstract We describe a new species of kukri snake (Oligodon Fitzinger, 1826) from the limestone karst formations of Satun and Trang Provinces in southern Thailand. Phylogenetic analyses based on three mitochondrial DNA fragments (12S–16S ribosomal rRNA and cytochrome b) recover the new species within the Oligodon cinereus species complex, where it forms a deeply divergent yet poorly supported clade sister to Oligodon saiyokSumontha et al., 2017 and another unnamed lineage currently referred to Oligodon cinereus (Günther, 1864) from southwest Myanmar. Morphologically, the new species is distinguished from all other members of the genus by the following combination of characters: ventral scales 189–193 with distinct lateral keeling; subcaudal scales 47–54, paired; anterior dorsal scale rows 17–19, with the reduction from 19 to 17 rows occurring above the 28th–30th ventral scale when present; maxillary teeth 8, blade-like and laterally compressed; dorsum olive–gray, plain; ventral surface white anteriorly, dark gray posteriorly; underside of tail dark gray, smeared with white. We briefly discuss the natural history and conservation status of this new species and provide observations of other kukri snakes inhabiting limestone karst habitats. Our study also incorporates genetic samples of four recently described Oligodon endemic to Thailand, all of which are recovered in the O. cinereus species complex. In agreement with previous studies, we demonstrate that species-level diversity within the O. cinereus species complex is underestimated, and additional sampling is necessary to revise this taxonomically challenging clade.

Two new nocturnal species of South Asian Cnemaspis Strauch, 1887 (Squamata: Gekkonidae) of the wynadensis clade from the southern Western Ghats, India

We describe two new medium-bodied, nocturnal species of South Asian Cnemaspis from the southern Western Ghats, Tamil Nadu, India in an integrative taxonomic framework. The two new species are phylogenetically and morphologically allied to the wynadensis clade and can be distinguished from other species of the wynadensis clade and each other by a combination of nonoverlapping morphological characters including body size, homogeneous dorsal pholidosis, the number of femoral pores and poreless scales separating these series, the number of ventral scales across the midbody and longitudinal scales from mental to cloaca, the number of dorsal granules around the body; and an uncorrected pairwise ND2 sequence divergence of 8.2–22.9 % (16S 4.2–12.2 %) from all other members in the clade. These are the first members of the wynadensis clade known from south of the Palghat Gap apart from C. bireticulata, a putative junior synonym of C. sisparensis that is likely to be distinct owing to morphological differences and geographic distance. Cnemaspis sanctus sp. nov. is from low coastal hills in Kanyakumari District at the southern tip of the Western Ghats and Cnemaspis persephone sp. nov. is from the Anaimalais, Anaimalai Tiger Reserve. Many more undescribed species of the wynadensis clade and South Asian Cnemaspis are likely to be found across the southern Western Ghats.

Another new species of karst-associated pitviper (Serpentes, Viperidae: Trimeresurus) from the Isthmus of Kra, Peninsular Thailand

We describe a new species of karst-dwelling pitviper from Chumphon Province of Peninsular Thailand, in the Isthmus of Kra, based on morphological and molecular data (2427 bp from cyt b, ND4 and 16S rRNA mitochondrial DNA genes). Morphologically, Trimeresurus kraensis sp. nov. is distinguished from other congeners by the following combination of morphological characters: a dark/bottle-green dorsum with reddish-brown or purple crossbands; pale green venter lacking dark dots; stripes present on the lateral sides of the ventrals; internasals generally in contact; one large supraocular scale on each side of the head; iris pale copper; tail brown with dark purplish-brown crossbars; dorsal scales in 21–21–15 rows; ventral scales 167 in a single male, 169–171 in females; subcaudal scales 62 in a single male, 52–54 in females, all paired. White vertebral spots present in males, located on approximately every two or four dorsal scales; dark brown spots forming discontinuous pattern present on 1–3 lateral dorsal scale rows; males with reddish-brown postocular stripe with jagged edges. The new species differs from the morphologically similar species Trimeresurus venustus s. str. by a notable divergence in cytochrome b mitochondrial DNA gene sequences (p = 5.9%).

Two new species of the Cnemaspisgalaxia complex (Squamata, Gekkonidae) from the eastern slopes of the southern Western Ghats.

Two new species allied to Cnemaspisgalaxia are described from the eastern slopes of the south Western Ghats, Tamil Nadu, India. Both new species are members of the ornata subclade within the beddomei clade. The two new species can be easily distinguished from all other members of the beddomei clade and each other by a combination of nonoverlapping morphological characters such as small body size, distinct colouration of both sexes, the number of dorsal tubercles around the body, the number or arrangement of paravertebral tubercles, the number of midventral scales across the belly and longitudinal ventral scales from mental to cloaca, besides uncorrected pairwise ND2 and 16S sequence divergence of ≥ 7.4% and ≥ 2.7%. The two new species are distributed from low elevation, deciduous forests of Srivilliputhur, and add to the five previously known endemic vertebrates from Srivilliputhur-Megamalai Tiger Reserve.

Another New Species of the Cyrtodactylus annulatus Complex (Squamata: Gekkonidae) from Maratua an Adjacent Island to Borneo, Indonesia

The region of Borneo is very interesting in its diversity of gekkonid lizards of the genus Cyrtodactylus. Until now, it is known to harbor 14 described species. Herein, we described a new member of this genus from the adjacent island of Maratua. Cyrtodactylus tehetehe sp. nov. is named after the specialty of the traditional cuisine of the Derawan Islands (sticky rice with coconut milk and a little salt wrapped in sea urchin skin, Echinoidea spp.). The new species forms a tight phylogenetic clade with Philippine taxa allied to C. annulatus and is sister to the Palawan species C. tautbatorum, a biogeographic surprise, given that C. jambangan and C. annulatus occur closer geographically, in the Sulu Archipelago. The new species can be distinguished from all other congeners by a combination of characters including maximum SVL, number of supralabials, infralabials, longitudinal dorsal tubercle rows, paravertebral tubercles, ventral scale rows, subdigital lamellae on fourth toe, by having tubercles on ventrolateral body folds, a single precloacal pore and enlarged precloacal scales, lacking tubercles on upper arm, enlarged femoral scales and respective pores, precloacal depression, and transversely enlarged median subcaudals.

Systematic revision of the Calotes jerdoni complex (Reptilia: Squamata: Agamidae) in the Pan-Himalaya

Abstract Owing to the harsh terrain, few biodiversity surveys have been carried out in the Pan-Himalaya Region. Among the understudied taxa from this region, Jerdon’s forest lizard, Calotes jerdoni, is believed to have a wide distribution, from northeast India to southwestern China. However, given the heterogeneous environment across its range and the lack of studies on this species, its taxonomy remains questionable. Using integrative taxonomic methods, we combined both morphological and genetic data from the type and topotypic specimens and examined the current taxonomic hypothesis of C. jerdoni across its range. Molecular data reveal that C. jerdoni as currently recognized, contains three deeply diverged lineages: one from the type locality in Northeast India, one from Western Myanmar, and another one from Southwestern China. The uncorrected genetic distances of mitochondrial coding gene ND2 among these three clades ranged over 10%. The Chinese population is sister to C. medogensis and paraphyletic to the remaining two clades of C. jerdoni. Morphological analyses confirm the results of the molecular analyses, where the Myanmar and Chinese populations can be diagnosed statistically in both univariate and multivariate space from the true C. jerdoni, as well as by a suite of reliable categorical morphological characters, including the size and shape of gular scales and ventral scales. To resolve the current taxonomic confusion, we resurrect the junior synonym, C. yunnanensis, for the Chinese population and expand its distribution to Myanmar, redescribe the elusive C. maria and C. medogensis based on its type material, and describe the remaining western Myanmar population as a new species. We further discuss the possibility of additional cryptic species within the complex in the Pan-Himalaya Region and provide a diagnostic key to all recognized members of the C. jerdoni complex.

Skin structure of the slow worm lizard Anguis fragilis (Anguidae, Sauria, Reptilia) with emphasis on the epidermal micro‐ornamentation in relation to the animal movements

AbstractSkin structure of the slow worm lizard Anguis fragilis (Anguidae, Sauria, Reptilia) with emphasis on the epidermal micro‐ornamentation in relation to the animal movements (Acta Zoologica, Stockholm). The structure of the skin and superficial micro‐ornamentation in the slow worm Anguis fragilis, a limbless lizard with a fossorial activity, was examined using histology, immunofluorescence, scanning and transmission electron microscopy. The scales, with a triangular to trapezoidal shape, are very overlapped and interlocked to form a smooth surface and are reinforced by osteoderms. The epidermis shows a thin Oberhautchen layer merged with a thicker beta‐layer that contains corneous beta‐proteins. The SEM survey detects a smooth surface made of tile‐like patterned Oberhautchen cells with irregular perimeters that form an interlocking surface. Disk‐like sensory organs of 15–20 μm diameter are observed only on the head scales, the first to sense the environment and contact the ground. Numerous Oberhautchen denticles, namely corneous thorns of about 0.2–0.3 μm, adorn the caudally directed perimeter of Oberhautchen cells in the ventral scales of the trunk and tail. This microstructure may determine gripping and increased friction with the substrate during the lateral undulating and forward movements of the slow worm. TEM observations reveal sparse short serrated protrusions of Oberhautchen cells that are largely merged with the underlying beta‐cells. Altogether, the scale surface of the slow worm efficiently suites this limbless lizard to its environment and lifestyle.

Another new species of Dibamus Dumril & Bibron, 1839 (Squamata: Dibamidae) from Nui Chua National Park, Ninh Thuan Province, Vietnam.

A new species of dibamid lizard, Dibamus deimontis sp. nov., is described based on eight specimens collected from the highlands of Nui Chua Mountain within Nui Chua National Park, Ninh Thuan Province, southern Vietnam. Dibamus deimontis sp. nov. co-occurs with the recently described Dibamus tropcentr, but is recorded at higher elevations (670700 m a.s.l. vs. 200280 m a.s.l.), and in a different habitat and microhabitats than the previous species. Our study represents the first report on the near sympatric occurrence of two Dibamus species. The new species can be distinguished from other congeners by the following combination of characters: rostral, labial and nasal sutures incomplete; two to three postoculars; three to five scales on the posterior edge of infralabial; 2225 midbody scale rows; 193225 ventral scales; 4755 subcaudal scales; 115 presacral and 27 tail vertebrae (in a single male specimen examined); and maximum snout-vent length 136.2 mm. We suggest this species should be considered as Vulnerable (VU) following the IUCNs Red List categories. Our study brings the number of species in the genus Dibamus to 26; Dibamus deimontis sp. nov. is the eighth species of Dibamus recorded in Vietnam, and underlines the importance of the country as a local center of reptilian diversity in Southeast Asia.