Topographical Anatomy of the Blunthead Treesnake, Imantodes cenchoa (Linnaeus, 1758) (Colubridae: Xenodontinae)

Abstract

Imantodes cenchoa (Duméril, 1853) is an arboreal, nocturnal and oviparous xenodontine snake, which feeds on amphibians and lizards. It is found in Central and South America, including northern and central Brazil. In this work, we investigated the relationship between topographic anatomy and habitat in I. cenchoa. Twenty specimens (13 non pregnant females and 7 males) were examined. The topographic anatomy study was realized through observations of the internal anatomy, particularly the position and size of lung, heart, liver, left and right gonads and left and right kidneys. Results showed that all the organs are located in a posterior position in relation to the snout vent length (SVL). The centre of gravity is found at about 74% of SVL in both males and females. In males, no positive allometry was observed among the positions of the organs. Negative allometry in females was observed regarding the position of the anterior tip of the left kidney, the anterior and posterior tips of the right kidney and in both ovaries. In males, negative allometry is present in the position of all the or gans. The distance between the last follicle and the cloaca was 8.78% of SVL. Our data corroborate the idea that the posterior position of all internal organs is linked to a habitat specialization of a snake, linking the arboreal species I. cenchoa with a relatively posterior internal topography.