The genus Atractus (Serpentes: Colubridae) in northeastern Argentina

Abstract

Abstract: We present a revision of Atractus in north-eastern Argentina based on the examination of newly collected specimens and most of the material available in Argentinean museums. Four species are reported: A. snethlageae, A. paraguayensis, A. reticulatus and A. taeniatus. Atractus badius was erroneously cited as occurring in Argentina based on a specimen from Las Palmas, Chaco province which is reassigned to A. snethlageae. This record represents a considerable southern extension of the known range of the species. Atractus paraguayensis is redescribed based on three new specimens. This species was previously known only from the holotype reported from "Paraguay" without definite locality data. Adult and juvenile colour patterns in life are described. The validity of some diagnostic characters is discussed, and new diagnostic characters are given for A. reticulatus and A. paraguayensis. All species examined showed noteworthy variation in colour pattern. Sexual dimorphism is reported in all species. The distributional patterns and phytogeographic areas occupied by each species in Argentina are discussed. We also characterize morphological variation for each and provide a key for the Argentinean species.