Phylogenetic Systematics Of Dispholidine Colubrids (Serpentes: Colubridae)

Abstract

Dispholidine colubrids are a group of arboreal African snakes that are distributed throughout sub-Saharan Africa. Despite their vast distribution and medical significance, the systematic relationships of this group remain poorly understood. I used molecular and morphological data in both a phylogenetic and a multivariate framework to study the evolutionary relationships and external morphology of these snakes. The results of the phylogeographic investigation based on two mitochondrial markers indicated the presence of two distinct evolutionary lineages of Dispholidus sp. in southern Africa that are largely geographically separated by the Great Escarpment and associated habitat. A study of the molecular systematics of dispholidine snakes using both mitochondrial and nuclear markers further corroborated those results, and suggest the presence of multiple distinct evolutionary lineages within the genus Dispholidus. It also provides strong support for the paraphyly of Thelotornis to the exclusion of Xyelodontophis uluguruensis. Lastly, a multivariate analysis of the external morphological characters commonly utilized in taxonomic keys and species accounts indicated that those characters are only partially able to distinguish taxa within this group. Snout-vent length, tail length, subcaudal and mid-dorsal scales were able to differentiate within the genera Thrasops and Rhamnophis, as well as specimens of Dispholidus sp. from Pemba Island.