We provide a molecular phylogeny of Asian pit vipers (the genus Gloydius) based on four mitochondrial genes (12S, 16S, ND4, and cytb). Sequences of Gloydius himalayanus, the only member of the genus that occurs south of the Himalayan range, are included for the first time. In addition, two new species of the genus Gloydius are described based on specimens collected from Zayu, Tibet, west of the Nujiang River and Heishui, Sichuan, east of the Qinghai-Tibet Plateau. The new species, Gloydius lipipengi sp. nov., can be differentiated from its congeners by the combination of the following characters: the third supralabial not reaching the orbit (separated from it by a suborbital scale); wide, black-bordered greyish postorbital stripe extending from the posterior margin of the orbit (not separated by the postoculars, covering most of the anterior temporal scale) to the ventral surface of the neck; irregular black annular crossbands on the mid-body; 23-21-15 dorsal scales; 165 ventral scales, and 46 subcaudal scales. Gloydius swildsp. nov. can be differentiated from its congeners by the narrower postorbital stripe (only half the width of the anterior temporal scale, the lower edge is approximately straight and bordered with white); a pair of arched stripes on the occiput; lateral body lakes black spots; a pair of round spots on the parietal scales; 21 rows of mid-body dorsal scales; zigzag dark brown stripes on the dorsum; 168–170 ventral scales, and 43–46 subcaudal scales. The molecular phylogeny in this study supports the sister relationship between G. lipipengisp. nov. and G. rubromaculatus, another recently described species from the Qinghai-Tibet Plateau, more than 500 km away, and indicate the basal position of G. himalayanus within the genus and relatively distant relationship to its congeners.

Venomous snakes often display extensive variation in venom composition both between and within species. However, the mechanisms underlying the distribution of different toxins and venom types among populations and taxa remain insufficiently known. Rattlesnakes (Crotalus, Sistrurus) display extreme inter- and intraspecific variation in venom composition, centered particularly on the presence or absence of presynaptically neurotoxic phospholipases A₂ such as Mojave toxin (MTX). Interspecific hybridization has been invoked as a mechanism to explain the distribution of these toxins across rattlesnakes, with the implicit assumption that they are adaptively advantageous. Here, we test the potential of adaptive hybridization as a mechanism for venom evolution by assessing the distribution of genes encoding the acidic and basic subunits of Mojave toxin across a hybrid zone between MTX-positive Crotalus scutulatus and MTX-negative C. viridis in southwestern New Mexico, USA. Analyses of morphology, mitochondrial and single copy-nuclear genes document extensive admixture within a narrow hybrid zone. The genes encoding the two MTX subunits are strictly linked, and found in most hybrids and backcrossed individuals, but not in C. viridis away from the hybrid zone. Presence of the genes is invariably associated with presence of the corresponding toxin in the venom. We conclude that introgression of highly lethal neurotoxins through hybridization is not necessarily favored by natural selection in rattlesnakes, and that even extensive hybridization may not lead to introgression of these genes into another species.

Snake envenoming is caused by many biological species, rather than a single infectious agent, each with a multiplicity of toxins in their venom. Hence, developing effective treatments is challenging, especially in biodiverse and biogeographically complex countries such as India. The present study represents the first genus-wide proteomics analysis of venom composition across Naja species (N. naja, N. oxiana, and N. kaouthia) found in mainland India. Venom proteomes were consistent between individuals from the same localities in terms of the toxin families present, but not in the relative abundance of those in the venom. There appears to be more compositional variation among N. naja from different locations than among N. kaouthia. Immunoblotting and in vitro neutralization assays indicated cross-reactivity with Indian polyvalent antivenom, in which antibodies raised against N. naja are present. However, we observed ineffective neutralization of PLA₂ activities of N. naja venoms from locations distant from the source of immunizing venoms. Antivenom immunoprofiling by antivenomics revealed differential antigenicity of venoms from N. kaouthia and N. oxiana, and poor reactivity towards 3FTxs and PLA₂s. Moreover, there was considerable variation between antivenoms from different manufacturers. These data indicate that improvements to antivenom manufacturing in India are highly desirable.

Background: Snakebite envenoming, classified as a neglected tropical disease, poses a significant threat to life in India, where it is estimated to cause 58 000 fatalities as well as 140 000 morbidities annually. To reduce the occurrence of snakebite, we need a comprehensive understanding of human–snake conflict ecology. Snake rescue networks represent a vital resource for gathering such ecological data. Methods: In this study, we utilised snake rescue data from 520 rescue encounters carried out by a local rescue network in Hooghly, West Bengal, from July 2020 to October 2022, to investigate patterns of human–snake conflict and the influence of climatic factors on these patterns. Results: The spectacled cobra Naja naja was the most encountered of the five venomous species involved in 365 rescues. Our analysis revealed a significant correlation between rescue location and venomous/non-venomous encounters, with non-venomous encounters being more prevalent inside built-up locations. Rainfall on the previous day significantly increased encounters and influenced the species involved, while daily minimum temperature also influenced encounters with venomous species. We also found that both Bungarus (krait) species present were mostly encountered between 18:00 h and midnight. Conclusions: This study highlights the multifaceted factors influencing human-snake conflicts in the region, including seasonality, geographic location, rainfall patterns, and temperature dynamics. It underscores the potential of snake rescue data as a valuable resource for deepening our understanding of regional variations in snake–human interactions.

Gloydius is a widespread pitviper group occurring from Eastern Europe to Korea and Siberia, with only one known species, G. himalayanus (Günther, 1864), found south of the Himalayas. We provide combined genetic and morphological data for G. himalayanus from specimens collected from Himachal Pradesh, India. Bayesian Inference and Maximum Likelihood phylogenetic analysis were performed on four concatenated mitochondrial genes, along with a multi-locus coalescent analysis of these and five additional nuclear genes. Our results indicate that G. himalayanus from the Chamba Valley, in western Himachal Pradesh, are highly distinct from the remaining studied populations. Haplotype networks of each nuclear locus showed that G. himalayanus contains high haplotype diversity with low haplotype sharing between the Chamba Valley population and populations from further west. Principal component analysis and canonical variate analysis conducted on morphological data of live and museum specimens also highlight the morphological distinctiveness of the Chamba population and we herein describe this population as a new species, Gloydius chambensis sp. nov. Recent descriptions of other new species of snakes from this valley underscores its isolation and suggests that further herpetological investigation of the highly dissected landscapes of the western Himalayas is needed to assess the true diversity of the region.

We present a genome assembly from an individual female Vipera berus (common adder; Chordata; Lepidosauria; Squamata; Viperidae). The haplotype-resolved assembly contains two haplotypes with total lengths of 1,695.0 megabases and 1,476.7 megabases, respectively. Most of haplotype 1 (98.45%) is scaffolded into 19 chromosomal pseudomolecules, while haplotype 2 is assembled to scaffold level. Haplotype 1 achieves the Earth Biogenome Project reference standard of 6.C.Q52. The mitochondrial genome has also been assembled and is 17.35 kilobases in length.