Squamate reptiles (lizards and snakes) are a pivotal group whose relationships have become increasingly controversial. Squamates include >9000 species, making them the second largest group of terrestrial vertebrates. They are important medicinally and as model systems for ecological and evolutionary research. However, studies of squamate biology are hindered by uncertainty over their relationships, and some consider squamate phylogeny unresolved, given recent conflicts between molecular and morphological results. To resolve these conflicts, we expand existing morphological and molecular datasets for squamates (691 morphological characters and 46 genes, for 161 living and 49 fossil taxa, including a new set of 81 morphological characters and adding two genes from published studies) and perform integrated analyses. Our results resolve higher-level relationships as indicated by molecular analyses, and reveal hidden morphological support for the molecular hypothesis (but not vice-versa). Furthermore, we find that integrating molecular, morphological, and paleontological data leads to surprising placements for two major fossil clades (Mosasauria and Polyglyphanodontia). These results further demonstrate the importance of combining fossil and molecular information, and the potential problems of estimating the placement of fossil taxa from morphological data alone. Thus, our results caution against estimating fossil relationships without considering relevant molecular data, and against placing fossils into molecular trees (e.g. for dating analyses) without considering the possible impact of molecular data on their placement.

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.

The family Xenophidiidae is an extremely rare and little-known family of snakes that contains only two species, Xenophidion acanthognathus Günther & Manthey and X. schaeferi Günther & Manthey that are each known only from their holotypes. We report on the rediscovery of X. schaeferi from two new locations in southern Peninsular Malaysia. The new specimens differ markedly from the holotype of X. schaeferi in colour pattern and are more akin to the patterning of X. acanthognathus from Borneo. However, molecular analyses of one of the new specimens reveal that it only differs from the holotype of X. schaeferi by a minimum sequence divergence of 0.27%. An expanded description of the species based on these specimens is provided and phenotypic variation within the species is discussed. We also report the first record of the genus Xenophidion from West Sumatra, Indonesia. These sensational discoveries continue to underscore the fact that southern Peninsular Malaysia and upland areas of Southeast Asia in general still harbour unrealized herpetological diversity and are still in need of field research-based taxonomic studies.

Twelve new karst-adapted species of the gekkonid genus Cyrtodactylus Gray are described from the Shan Hills and Salween River Basin of Myanmar. Three species occur in rocky habitats along karst ridges and nine species are microendemics restricted to isolated karst caves and towers. This high, localized diversity underscores the archipelago-like nature and microendemism associated with karst habitat-islands. Eleven of the 12 new species are not related to other Indo-Burmese species and form four monophyletic species groups nested within a larger Indo-Chinese clade of Southeast Asian species. Phylogenetic relationships and distributions indicate Cyrtodactylus originated in the Himalayan uplands and dispersed westward through Myanmar with subsequent invasions back into eastern and southern Myanmar. These new species highlight the understudied nature of karst biodiversity in general and karst herpetology in particular. Extensive karst ecosystems throughout the massive Shan Plateau of eastern Myanmar remain largely unexplored and are likely to harbour tens—if not hundreds—of undiscovered species. The unique and complex structure of understudied limestone ecosystems throughout Southeast Asia are habitats in which amphibians and reptiles have specialized, speciated and become endemic. In an age of biodiversity crisis, managing and conserving these ecosystems throughout Southeast Asia should be given greater priority. A key to the species of Cyrtodactylus of Myanmar is provided.