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Species diversity of reptiles is much higher in Sundarban than in other mangrove ecosystems in India. Presently snakes are declining in Sundarban due to habitat loss caused by tremendous population pressure. Besides, irresponsible killing to avoid snakebite both from poisonous and nonpoisonous varieties is another reason for the gradual declining snake population. According to an intensive household survey in 35 villages in Sundarban, about 22 species (five poisonous and 17 non-poisonous) of snakes have been identified and there appears to have been a general decline in densities. On the contrary, a large number of people are bitten and die from snakebite every year with 0.57 and 0.34 vulnerability and mortality rate per 10,000 people, respectively. The two most commonly observed poisonous species are the common krait, Bungarus caeruleus (51 %) and common cobra, Naja naja (40 %), and that of non-poisonous varieties are the Ptyas mucosus (41 %), Typhlina bramina (34 %), Xenochrophis piscator (12 %), and Amphiesma stolata (10 %). Apart from killing of snakes out of fear; habitat loss, unscientific handling of snakes by snake catchers and charmers, and netting by fisherman contributes to snake mortality to a large extent; 72 % killed snakes are of poisonous varieties, 60 % of which are B. caeruleus, the most venomous snake in Sundarban. This paper is an attempt to highlight some of the important conservation efforts like the introduction of snake firms, alternative employment channels for the snake charmers and catchers, and mass awareness campaign through panchayet (village level governing body) and local NGOs.

Unresolved phylogenetic relationships within the subfamily Natricinae continue to exist, including the position of the genus Xenochrophis. In the present study, two mitochondrial genes (cytochrome b, 12S rRNA) and one nuclear gene (c-mos) were used to infer the phylogenetic relationships among the members of Natricinae, with a special emphasis on the position of the genus Xenochrophis. Two statistical methods, Maximum Likelihood and Bayesian Inference, were used for phylogenetic reconstruction. Both the mitochondrial and nuclear datasets produced sufficiently resolved and congruent topologies. Our findings placed the genus Xenochrophis within Natricinae consistently with strong nodal support. Findings also revealed a close association between two Indian natricid snakes, Xenochrophis piscator and Xenochrophis schnurrenbergeri. However Xenochrophis vittatus, from Indonesia, does not cluster with the remaining species of Xenochrophis, suggesting a nonmonophyly of this genus. Overall Natricinae was found to be monophyletic because the two genera, Psammodynastes pulverulentus and Amplorhinus multimaculatus, are now known to be members of the Lamprophiidae. This study also finds a close relationship between the endemic species Lycognathophis seychellensis with the African natricids.

Recent studies have demonstrated that thermoregulatory behavior occurs not only in posthatching turtles but also in turtles prior to hatching. Does thermoregulatory behavior also occur in the embryos of other reptile and bird species? Our experiments show that such behavior is widespread but not universal in reptile and bird embryos. We recorded repositioning within the egg, in response to thermal gradients, in the embryos of three species of snakes (Xenochrophis piscator, Elaphe bimaculata, and Zaocys dhumnades), two turtles (Chelydra serpentina and Ocadia sinensis), one crocodile (Alligator sinensis), and four birds (Coturnix coturnix, Gallus gallus domesticus, Columba livia domestica, and Anas platyrhynchos domestica). However, we detected no significant thermoregulation by the embryos of two lizard species (Takydromus septentrionalis and Phrynocephalus frontalis). Overall, embryonic thermoregulatory behavior is widespread in reptile as well as bird species but may be unimportant in the small eggs laid by most lizards.

The Asiatic water snake (Xenochrophis piscator) is a small-sized snake and can be found in or near freshwater lakes or rivers. This species is listed in Appendis III of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. We isolated and characterizated 9 polymorphic microsatellite loci in this species to evaluate their population polymorphism using 176 individuals collected from Quanzhou in southern China. These markers revealed a high degree of genetic diversity (20–50 alleles per locus) and heterozygosity (H O ranged from 0.137 to 0.944 and H E ranged from 0.884 to 0.953). No locus exhibited significant deviations from Hardy–Weinberg equilibrium. There was no evidence of linkage disequilibrium among pairs of loci. These microsatellite markers will be useful for future study of gene flow, population structure, and evolutionary history of X. piscator.

Morphological variation was investigated across the entire geographic range of the snakes of the Xenochrophis piscator species group. Our results, based on morphological univariate analyses, show the existence of several well-definedclusters identified as species. Xenochrophis flavipunctatus (Hallowell, 1861) is distinct from X. piscator (Schneider, 1799)and sympatric with it over a large area. Xenochrophis tytleri (Blyth, 1863) is confirmed as the valid combination for thepopulation living on the Andaman Islands. Xenochrophis asperrimus (Boulenger, 1891) is confirmed, with species status,for populations from Sri Lanka. Xenochrophis melanzostus (Gravenhorst, 1807) is accepted, as a distinct species mostprobably endemic to Java. Xenochrophis schnurrenbergeri Kramer, 1977 is confirmed for populations from Nepal,southeastern Pakistan, and northern and eastern India. Tropidonotus sanctijohannis Boulenger, 1891 seems to be amontane colour morph of X. piscator and is not regarded here as valid. The second population of “X. piscator“ on SriLanka is regarded as different from that of the mainland, but it is not named here due to the uncertain relationships amongpopulations of southern India and Sri Lanka. The variation of X. piscator sensu stricto is discussed. All taxa areredescribed on the basis of new material. The history of all synonyms is discussed and neotypes are designated for Hydrus palustris Schneider, 1799, Coluber melanzostus Gravenhorst, 1807 and Amphiesma flavipunctatum Hallowell, 1861. The holotype of Hydrus piscator Schneider 1799 has been rediscovered and is discussed.