Cranial osteology and molecular phylogeny of Argyrogena fasciolata (Shaw, 1802) (Colubridae: Serpentes)

Abstract

Descriptive accounts of the cranial osteology of snakes is important for systematics, functional morphology and also, to some extent, palaeontology. In the present study, we describe the skull of Argyrogena fasciolata, a south Asian colubrid snake, in detail. Bones of the snout unit of this snake are adapted for a fossorial mode of life whereas the braincase lacks any adaptations related to such an existence. We also compared its skull with other snakes belonging to sixteen other genera which together form the large clade containing Afrotropical, Palaearctic and Saharo-Arabian racers/whip snakes. The comparison shows that the cranium of A. fasciolata bears more similarity with that of Platyceps spp, differing mostly in three characteristics pertaining to premaxilla, nasal and pterygoid bones, than it does with crania of other genera. This suggests a closer relationship between those two genera. We also performed molecular phylogenetic analyses on three mitochondrial loci using Maximum Likelihood and Bayesian Inference optimality criteria. The resultant phylogenies indeed recover A. fasciolata as sister to Platyceps spp.