A redescription of the extinct snake genus Colombophis is presented, on the basis of new specimens from the late Miocene of southwestern Brazilian Amazonia, and those previously reported for the middle Miocene of Colombia and Venezuela. The reappraisal of Colombophis allows the recognition of a new species, C. spinosus sp. nov. The revised diagnosis of the genus is based on the midtrunk vertebrae, distinct from those of other snakes mainly in the features of the neural arch, position and shape of the neural spine, inclination of the zygapophyses, shape of the centrum, and development of the haemal keel. The affinities of Colombophis with “Anilioidea” are still unresolved; it is distinguished from all known extinct and extant “anilioids” due to its great vertebral size and the frequent presence of paracotylar foramina. The posterior paired apophyses of the haemal keel in some vertebrae, and the high neural spine of C. spinosus also contrast significantly with the “anilioid” genera, making the allocation of the genus into this probably paraphyletic group not well supported. Here, we recognized Colombophis as a basal alethinophidian of uncertain relationships.

Key words: Serpentes, Alethinophidia, Colombophis, Miocene, South America.

Annie S. Hsiou [anniehsiou@gmail.com] and Jorge Ferigolo [jorge.ferigolo@fzb.rs.gov.br], Seção de Paleontologia, Museu de Ciências Naturais, FZB-RS, Av. Salvador França, 1427, CEP: 90690-000, Jardim Botânico, Porto Alegre, Rio Grande do Sul, Brazil; Adriana M. Albino [aalbino@mdp.edu.ar], CONICET, Departamento de Biología, Universidad Nacional de Mar del Plata, Funes 3250, 7600 Mar del Plata, Argentina.