Hidden in plain sight: Didelphis albiventris (Didelphimorphia: Didelphidae) might not be a single species

The white-eared opossum, Didelphis albiventris Lund, 1840, is one of the most widely distributed South American marsupials. As currently defined, the species ranges from northeastern and central Brazil through Paraguay and central Bolivia, all of Uruguay, and in Argentina, from the north to northern Patagonia. Previous phylogeographic analyses found two haplogroups, one corresponding to northeastern and central Brazil and the other to southern Brazil, Bolivia, and Paraguay. In those studies, differentiation was based on the geographic distance between both regions and the presence of geographic barriers among populations. The aims of the present contribution were to perform population-genetic analyses using the mitochondrial markers cytochrome c oxidase 1 (COI) and cytochrome b (cyt b) in order to elucidate the phylogeographic history of this species by incorporating samples from Argentina into the published datasets, and to evaluate whether there is more than one taxonomic entity under the name Didelphis albiventris . We studied the craniodental morphology of the species and used environmental niche modeling (ENM) as an additional methodology to investigate the environmental factors affecting its distribution. Our molecular, morphological, and ENM results strongly suggest the existence of two taxonomic entities under Didelphis albiventris , one in southern Brazil, Argentina, Paraguay, Uruguay, and Bolivia, and the other in central and northern Brazil. Data from specimens in the missing middle part of the taxon’s range and evidence from nuclear markers are needed before formalizing a taxonomic split.