Morphological adaptations to arboreal habitats and heart position in species of the neotropical whipsnakes genus Chironius

The evolution of arboreality in snakes is accompanied by modifications that are remarkably similar across species. Gravity is one of the most important selective agents, and arboreal snakes present adaptations to circumvent the gradient of pressure, including modifications on heart position (HP) and body slenderness (BS). However, the degree to which different life-history traits influence the cardiovascular system of snakes remains unclear. Here, we used an ecological and a phylogenetic approach to explore the relationship between habitat, HP, BS, and heart size (HS) in five species of the neotropical whipsnakes genus Chironius that occupy terrestrial, semiarboreal, and arboreal habits. Our ecological comparison indicated that the arboreal species have the most posterior-positioned heart, the most slender body, and the smallest HS, whereas the terrestrial representative of the group exhibited the most anterior heart, the less flattened body, and the largest HS. After removing the phylogenetic effect, we found no difference in HP and BS between terrestrial and arboreal species. Habitat only differed when contrasting with HS. Body slenderness and HS were correlated with HP. Our results suggest that different restrictions, such as anatomical constraints, behavior, and phylogenetic inertia, may be important for the studied species. © 2013 The Royal Swedish Academy of Sciences.

Ecomorfologia e uso de recursos das espécies de Chironius (Serpentes, Colubridae) na Serra do Mar

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

TAXONOMIC STATUS OF CHIRONIUS MULTIVENTRIS AND CHIRONIUS COCHRANAE (SERPENTES)

Recently four subspecies of Chironius multiventris were recognized as valid distinct species: C. in. foveatus, C. in. multiventris, C. in. cochranae, and C. m. septentrionalis. Although C. foveatus and C. septentrionalis clearly deserve specific status, a re-evaluation of the characters pointed in the literature as diagnostic of C. multiventris and C. cochranae does not support their recognition as valid distinct taxa. Additionally, our analysis of the scutellation pattern, continuous characters, and hemipenial morphology of 34 specimens, and of the available data in literature, shows that there are no significant differences between them. We therefore suggest that C. cochranae should be synonymized with C. multiventris.

Snakes from coastal islands of State of São Paulo, Southeastern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Composição faunística, ecologia e história natural de serpentes em uma região no sudoeste da Amazônia, Rondônia, Brasil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)