Molecular Systematics of Neotropical Xenodontine Snakes. III. Overview of Xenodontine Phylogeny and the History of New World Snakes

Abstract

Microcomplement fixation immunological data are presented concerning the relationships of several genera of xenodontines to 2 major clades within that radiation, the previously recognized Central and South American lineages. Heterodon, Farancia, Carphophis and Conophis probably represent independent lineages. The phylogenetic placements of Diadophis and Contia are ambiguous. Comparisons with representatives of other colubrid lineages do not confirm that the xenodontine lineages discussed are monophyletic. No association can be demonstrated between any xenodontine lineage and representatives of the other lineages tested. The albumin divergence among New World colubrines strongly suggests that they are not monophyletic relative to Old World colubrines and that the diversification of New and Old World colubrine genera occurred subsequent to the separation of the major xenodontine lineages. Xenodontines may be older than the fossil record indicates and an African origin is as likely as an Asian-North American origin for the Neotropical lineages.