Molecular systematics of neotropical cat-eyed snakes: a test of the monophyly of Leptodeirini (Colubridae: Dipsadinae) with implications for character evolution and biogeography

The Leptodeirini has been presumed to be a monophyletic assemblage based on albumin immunological data and morphology and consisted of neotropical cat-eyed snakes (Leptodeira), blunt-headed vine snakes (Imantodes), nightsnakes (Eridiphas, Hypsiglena, and Pseudoleptodeira), and the cloud forest snake (Cryophis). In the present study, approximately 1.4 kb of mitochondrial DNA sequence data (from cob and nad4) were collected to test the monophyly of the Leptodeirini. These data were analysed using maximum parsimony, maximum likelihood, and Bayesian methods. None of the results supported the monophyly of the Leptodeirini. There was strong support for a clade containing Imantodes and Leptodeira, and another clade containing the nightsnakes, with the latter placed closer to Cryophis and other dipsadine genera (Sibon, Dipsas, and Atractus). This partial reassessment of the Dipsadinae infers the group to have an ancestral condition of being rear-fanged, mildly venomous, and feeding on ectothermal vertebrates, with a more derived radiation that has lost the rear-fanged, venomous condition and has a diet specialized on invertebrates. A brief discussion on the biogeography of the dipsadines shows the group to be much older (Palaeocene), consistent with earlier views, as opposed to a more recent (Miocene) hypothesis, as has been recently suggested.