Despite recent progress in our understanding of diversity within the genus Trimeresurus Lacépède, 1804, the subgenus Popeia Malhotra & Thorpe, 2004, distributed across most parts of East and Southeast Asia, remains taxonomically challenging. We applied an integrative taxonomic approach including analyses of morphological data and four mitochondrial genes (12S and 16S rRNA, cytochrome b, and NADH dehydrogenase subunit 4), along with examination of available type material, to address longstanding taxonomic questions in one clade within Popeia, the T. popeiorum group, and reveal a high level of hidden diversity of these snakes in the Indo-Burma Biodiversity Hotspot. We confirm that T. popeiorum Smith, 1937 sensu stricto is restricted to Northeast India, eastern Nepal, southern Bhutan, southeastern Bangladesh, western Yunnan Province (China), and northern and southwestern Myanmar. We further confirm that the recently described species T. yingjiangensis Chen et al., 2019 is a junior synonym of T. popeiorum. In addition, we discovered that the combination Trimesurus [sic] elegans Gray, 1853 is a valid senior synonym of T. popeiorum and threatens the stability of the latter taxon. Therefore, in order to protect the nomen popeiorum and in accordance with Article 23.9 of the International Code of Zoological Nomenclature, we regard the taxon Trimesurus elegans as a nomen oblitum and render Trimeresurus popeiorum a nomen protectum. Examination of a larger series of specimens allows us to describe two new cryptic species of Trimeresurus from the Indo-Burma Region. This study brings the total number of species in the subgenus Popeia to six and also suggests that the subspecific taxonomy of the T. sabahi complex requires further investigation. We urge adequate actions regarding the conservation of the newly discovered species and recommend further studies on their toxicology.

A new species of green pit vipers of the genus Trimeresurus Lacépède, 1804 is described from the lowlands of western Arunachal Pradesh state of India. The new species, Trimeresurus salazar, is a member of the subgenus Trimeresurus, a relationship deduced contingent on two mitochondrial genes, 16S and ND4, and recovered as sister to Trimeresurus septentrionalis Kramer, 1977. The new species differs from the latter in bearing an orange to reddish stripe running from the lower border of the eye to the posterior part of the head in males, higher number of pterygoid and dentary teeth, and a short, bilobed hemipenis. Description of the new species and T. arunachalensis Captain, Deepak, Pandit, Bhatt & Athreya, 2019 from northeastern India in a span of less than one year highlights the need for dedicated surveys to document biodiversity across northeastern India.

A new cryptic species of green pit viper is described from northeast India, based on specimens collected from the state of Mizoram and Meghalaya. The new species is a member of the subgenusViridoviperaand is sister toTrimeresurus medoensisbased on molecular data for mitochondrial cytochrome b gene, whereas resemblesTrimeresurus gumprechtimorphologically. A combination of characters helps delimit the new species from its congeners. Description of the new species highlights the need for dedicated surveys across northeast India to document its reptilian diversity, as this represents the third new species of the genus to be described in the past three years.

The pit viper snake genus Trimeresurus Lacépède, 1804 sensu lato, is a diverse group of nocturnal serpents comprising over 61 species. The genus is morphologically heterogeneous and has been divided into several subgenera. We present an updated phylogeny of Asian pitvipers and propose a revised classification. Additionally, we revise the taxonomy of T. popeiorum Smith, 1937 and propose taxonomic changes with support from molecular and morphological data. We restrict T. popeiorumsensu stricto to northeastern India, Bangladesh, southern China, and northern Myanmar; populations beyond these areas require further assessment. We also synonymize T. yingjiangensisChen et al., 2019 with T. popeiorum based on overlapping morphological characters, molecular data, and distribution. The findings shed new light on the taxonomy of T. popeiorum, warranting the need for assessing the population of T. popeiorum from southeast Asia.

The gekkonid lizard genusHemidactylusOken is the second most species-rich genus of geckos with greatest diversity in the tropical regions of the world. Some species of the genus are commensal and widespread; however, there are several endemic lineages with restricted distribution. India is home to at least 35 species, with 20 endemic species and the number is steadily increasing with exploration of new habitats and integrated taxonomic approach including molecular data. We made investigations into the molecular and morphological variation throughout the distribution ofHemidactylus triedrusDaudin, 1802 based on fresh specimens, literature review, museum material and molecular data. Results from morphological, molecular and micro-CT based anatomical data are unequivocal and show thatH. triedrusis a species complex represented by three species,H. triedrussensu stricto and two undescribed taxa.H. subtriedrusJerdon, 1854 syn. nov. was found to be morphologically similar to the type specimen ofH. triedrus, and genetically embedded in a clade containingH. triedrussensu stricto and is here treated as a junior synonym ofH. triedrus, whereasH. lankaeDeraniyagala is referred to asnomen dubiumgiven that the types are presently not traceable and the original description is inadequate in diagnosing the taxon. The populations from western-central India and parts of Pakistan, and from southern Karnataka are distinct and diagnosable, and are herein described as two new species, respectively. Morphological and molecular data support the distinctiveness of the new species. The present work resolves a taxonomic turmoil that lasted over two centuries highlighting the need for studies that integrate morphological and molecular data.

The genus Cyrtodactylus has recently been classified phylogenetically into several clades, subclades, groups, and some into Sri Lankan Cyrtodactylus. Certain complexes from the Indian subcontinent have been assigned to the “C. triedrus group”. This group is comprised of medium-sized species (SVL 50.6–105.7 mm) and are composed of five major species complexes: fraenatus, triedrus, deccanensis, jeyporensis, and collegalensis. Among these complexes, the latter four are composed of ground and litter dwelling species, which were previously assigned to the genus Geckoella; and is currently being treated as a subgenus. Cyrtodactylus triedrus, an endemic species of Sri Lanka, has long been considered a widely distributed single species in this part of the world. Based on morphological and phylogenetic evidences, we demonstrate that C. (G.) triedrus is not a single species, but a species complex. We also describe a new species that is restricted to intermediate savanna-mixed dry lowland forested habitats. Furthermore, we resurrect Geckoella punctata, assign it to the genus Cyrtodactylus and designate a lectotype that we redescribe. The genetic divergence across species of the C. triedrus clade varies between 11–26% in the studied fragment of the mitochondrial NADH dehydrogenase subunit 2 gene. The molecular phylogeny of the ground dwelling radiation of the subgenus Geckoella indicates deep splits between the Indian species and Sri Lankan endemic C. (G.) triedrus sensu stricto, and between Indian dry and wet zone clades. Cyrtodactylus (G.). triedrus is restricted to the moist or submontane forests in the Central highlands of Sri Lanka and is redescribed herein based on its holotype. http://zoobank.org/urn:lsid:zoobank:org:pub:3B37037C-EE9F-4011-BEC9-47E1F3BB6779