The status of Eurostus dussumierii and Hypsirhina chinensis (Reptilia, Squamata, Serpentes): With comments on the origin of salt tolerance in homalopsid snakes

Abstract

The Kerala mud snake, Enhydris dussumierii Duméril, Bibron & Duméril, has long been known only from syntypes collected in the nineteenth century, but more recent specimens have provided the opportunity for molecular work. Using Bayesian phylogenetic analysis of 2200 base pairs of cytb, 16S, and c-mos, we recovered the Kerala mud snake as the sister species to the Chinese mud snake, Enhydris chinensis (Chinese–Vietnamese endemic). The DNA results establish the position of dussumierii and chinensis as separate from the Enhydris clade, and together they form the sister group to most of the other fanged homalopsids ((Bitia+Cantoria) + (Erpeton+Gerarda+Fordonia) + (Myron+Pseudoferania) + (Enhydris punctata) + (Homalopsis+Enhydris bocourti) + (Cerberus)). Here we resurrect Ferania Gray for Enhydris sieboldii Gray, establish a new genus for the E. chinensis clade (bennettii+chinensis), and apply the generic replacement name Dieurostus Berg to E. dussumierii Duméril, Bibron & Duméril. A biogeographic scenario is proposed based on the ecology, distribution and salt tolerance of the species composing a hypothesized (not supported with molecular evidence) Asian coastal lineage that is distributed from Pakistan's Indus River delta to temperate coastal China.