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Population estimates and microhabitat characteristics are widely used to support conservation decisions. However, there had been no surveys focusing on the population status of the endemic and Critically Endangered Ta Kou bent-toed gecko to inform conservation actions across its distribution range. In this study, we conducted the first field surveys to assess its population status using the mark–capture–recapture method, determine microhabitat characteristics, and identify anthropogenic threats to the species’ survival in Binh Thuan Province, Vietnam. Based on our study results, Cyrtodactylus takouensis was only recorded on granitic rocks at various elevations from 265 to 694 m a.s.l. In total, 148 individuals of C. takouensis were detected in the dry season, and 95 individuals of C. takouensis were encountered in the rainy season. Of these, 73 and 51 adults were documented during the two seasons, respectively. The estimated total population size of C. takouensis was 315 individuals in the dry season (95% confidence intervals ranging between 189 and 581 individuals), whereas it comprised 149 individuals, calculated using the Petersen–Lincoln and Schnabel formula, in the rainy season (95% confidence intervals ranging between 108 and 361 individuals). The estimated difference in total population size was probably due to several factors, such as the rapid growth of interlaced vines making parts of the surveyed transects inaccessible during the rainy season, weather variations, and differences in survey effort and detection probability. Additionally, several microhabitat variables and species behaviors were investigated in both seasons. However, humidity was the only significant environmental variable when compared between the two seasons. Moreover, we found that tourism activities and parasites could pose threats to C. takouensis on Ta Kou Mountain. However, no structured or quantitative framework was employed to assess these risks in this study. Further research is needed to quantify factors affecting the species’ survival. Full article

An integrative taxonomic study recognized a new species of the Cyrtodactylus pulchellus group from Kanchanadit District, Surat Thani Province, Southern Thailand. Phylogenetic analyses of the mitochondrial ND2 gene revealed a new species, Cyrtodactylus kanchanaditsp. nov., that is closely related to C. lekaguli. The new species differs from its sister lineage by bearing mean genetic divergence of 4.53% and significant differences in both mensural and morphometric characters (p < 0.05). Cyrtodactylus kanchanaditsp. nov. can be differentiated from the remaining members of the C. pulchellus species group because of its genetic divergence of ≥7.99% and a combination of differences in body size: 11–15 supralabial and 10–12 infralabial scales, 29–35 paravertebral tubercles, 18–23 longitudinal rows of dorsal tubercles, 32–37 rows of ventral scales, 20–23 subdigital lamellae on the fourth toe, 32–37 femoroprecloacal pores in adult males, and four or five dark body bands; weak tuberculation on body; absence of tubercles in the ventral body fold, absence of precloacal pores in females, and absence of scattered pattern of white tubercles on dorsum; presence of precloacal groove depression; and maculated white caudal bands. Cyrtodactylus kanchanaditsp. nov. is currently known from its type locality. Full article

Karstic landscapes are immense reservoirs of biodiversity and range-restricted endemism. Nowhere is this more evident than in the world’s third-largest vertebrate genus Cyrtodactylus (Gekkonidae) which contains well over 300 species. A stochastic character mapping analysis of 10 different habitat preferences across a phylogeny containing 344 described and undescribed species recovered a karst habitat preference occurring in 25.0% of the species, whereas that of the other eight specific habitat preferences occurred in only 0.2–11.0% of the species. The tenth category—general habitat preference—occurred in 38.7% of the species and was the ancestral habitat preference for Cyrtodactylus and the ultimate origin of all other habitat preferences. This study echoes the results of a previous study illustrating that karstic landscapes are generators of species diversity within Cyrtodactylus and not simply “imperiled arks of biodiversity” serving as refugia for relics. Unfortunately, the immense financial returns of mineral extraction to developing nations largely outweighs concerns for biodiversity conservation, leaving approximately 99% of karstic landscapes with no legal protection. This study continues to underscore the urgent need for their appropriate management and conservation. Additionally, this analysis supports the monophyly of the recently proposed 31 species groups and adds one additional species group. Full article

Lizards and snakes (squamates) are known for their varied sex determining systems, and gecko lizards are especially diverse, having evolved sex chromosomes independently multiple times. While sex chromosomes frequently turnover among gecko genera, intrageneric turnovers are known only from Gekko and Hemidactylus. Here, we used RADseq to identify sex-specific markers in two species of Burmese bent-toed geckos. We uncovered XX/XY sex chromosomes in Cyrtodactylus chaunghanakwaensis and ZZ/ZW sex chromosomes in Cyrtodactylus pharbaungensis. This is the third instance of intrageneric turnover of sex chromosomes in geckos. Additionally, Cyrtodactylus are closely related to another genus with intrageneric turnover, Hemidactylus. Together, these data suggest that sex chromosome turnover may be common in this clade, setting them apart as exceptionally diverse in a group already known for diverse sex determination systems. Full article