Systematic review of the polychromatic ground snakes Atractus snethlageae complex reveals four new species from threatened environments

We review the Atractus snethlageae species complex based on the examination of 330 specimens throughout its entire distribution, including its type series. We redefine A. snethlageae and recognize four new species previously assigned to it in the literature and natural history collections. Two of them are diagnosed through both phenotypic (meristic, morphometric, color pattern, and male genital structure) and molecular (phylogeny) evidence, while the other two are recognized on the basis of morphological characters only. We show that some Amazonian lowland species have more restricted ranges. The area covering the eastern portion of the state of Pará and western portion of the state of Maranhão in Brazil harbors restricted endemism for Atractus. This biogeographically important region is also the most threatened within Amazonia. Finally, we discuss the expected changes in the taxonomy of ground snakes with more robust hypotheses based on well-sampled phylogenies.