The rare Andean pitviper Rhinocerophis jonathani (Serpentes: Viperidae: Crotalinae): redescription with comments on its systematics and biogeography

Rhinocerophis jonathani is one of the few species of the Neotropical pitvipers that inhabit xeric areas at elevations above 2000 m in the Andes. We redescribe the species based on new specimens found in southern Bolivia and northwestern Argentina and provide new data on lepidosis, coloration, hemipenial morphology and the first description of cranial osteology. Rhinocerophis jonathani exhibits a suite of unusual features that are of systematic value within bothropoid genera.

We compare the species with the phenotypically similar R. alternatus and the probably sympatric R. ammodytoides to address phylogenetic affinities. The new localities for Rhinocerophis jonathani extend the known range of the species southwards, provide data on its habitat and are the first records of its presence in Argentina. This pitviper occurs in a tropical-subtropical transition area in the Southern Andes and is likely to be derived from the Chacoan fauna.