Estudo sobre a folidose, morfometria e dimorfismo sexual de Philodryas patagoniensis (Girard, 1858) (Squamata, Colubridae)

Abstract

The Colubridae family encompasses the largest group of snakes, with more than 1772 described species around the world. The genus Philodryas is represented by 18 species, 13 of which occur widely distributed in Brazil. External morphology and color patterns are essential in studying sexual dimorphism and taxonomy of snake species. In this paper we intend to assess and compare, examining possible differences in folidose and morphometric aspects, the morphology between the sexes of 355 specimens Philodryas patagoniensis, from 18 Brazilian states and the Federal District, obtained in nine herpetological collections. According to the Wilcoxon test, mature specimens exhibited sexual dimorphism regarding the snout-vent length, tail length, number of ventral scales, number of subcaudal scales and head length, in mature individuals. The analysis of variance showed that mature females are larger than mature males, both in snout-vent length, as in tail length. This sexual dimorphism is considered a common pattern for colubrids, which may be related to reproduction, ensuring a body size that allows the production of larger and more numerous eggs. Females of P. patagoniensis have a greater number of ventral scales than males. Specimens that show more than 102 subcaudal scales are males; females show less than this value. This evidences sexual dimorphism. Analyzed specimens of P. patagoniensis also exhibit two distinct color patterns without, however, any geographical or sexual differences that justify these patterns.