Controversial snake relationships supported by reproductive anatomy

Since the advent of molecular character sets in phylogenetic systematics our understanding of the evolutionary history of snakes has changed considerably. In some cases the novel topologies reconstructed from molecular datasets have left researchers puzzled, as no morphological feature seems to support the new relationships found. This is the case for 'Amerophidia'sensu Vidal et al. (2007; Biology of the Boas and Pythons, Eagle Mountain: Eagle Mountain Publishing; Aniliidae + Tropidophiidae), a grouping of the Red Pipesnakes and Neotropical Dwarf Boas. We contend that in some cases the apparent lack of historical morphological support for the molecular phylogenies is due to our poor understanding of the organisms as a whole, and not the complete lack of morphological support for controversial clades. For example, we found novel evidence from reproductive anatomy that demonstrates a unique association of the oviducts and cloaca in Amerophidia. Whereas in all other female squamates the oviducts communicate directly with the cloaca, the oviducts of Aniliidae and Tropidophiidae communicate with diverticuli of the cloaca. At present this is the only unambiguous synapomorphy for the Amerophidia. We feel that confirmation of controversial molecular relationships will revolve around the investigation of non-traditional morphological characters such as reproductive anatomy.