Two genera of colubroid snakes are known to swallow eggs whole, slit the shell, swallow the contents of the egg, and spit out the remains of the shell. In Africa, there are 13 species of egg-eating snakes of the Genus Dasypeltis. In India, there is one species in the genus Elachistodon, the Indian Egg-eater, Elachistodon westermanni. Because of their similar diet and morphological adaptations and the shared biogeographic history between the Indian sub-continent and the continent of Africa it has long been assumed that the two genera shared a common ancestor. Mohan et al. (2018) amplified three mitochondrial genes and one nuclear gene from E. westermanni and reconstructed molecular phylogeny utilizing published sequences to understand the evolutionary relationships between the African, and the Indian egg-eating snakes. They used morphological characters to reinforce our inferences on phylogenetic relationships. Surprisingly, they show that the Indian egg-eater is sister to cat snakes of the Genus Boiga, and it does not share recent ancestry with the African egg-eating snakes. Morphological character states point at similarities between Elachistodon and Dasypeltis only in characters associated with their feeding behavior. Elachistodon westermanni was similar to the Boiga spp. in several other morphological characters, and they provisionally assign E. westermanni under the genus Boiga. Compilation of records of E. westermanni across the Indian subcontinent over the years revealed a positive “Lazarus” effect. The authors conclude that the egg-eating behavior and the associated morphological characters in the snake genera Dasypeltis and Elachistodon are a result of convergent evolution. Based on the conservation status of E. westermanni, it could serve as a flagship species to conserve important wildlife habitats that are being lost rapidly in India.
Mohan AV, Visvanathan AC, Vasudevan K. 2018. Phylogeny and conservation status of the Indian egg-eater snake, Elachistodon westermanni Reinhardt, 1863 (Serpentes, Colubridae). Amphibia-Reptilia 2018 May 31.