Bibimys
As with most of the species in the South American Sigmodontinae, Bibimys has been arranged as a genus based mainly on morphological differences from the other living genera.Bibimys belongs to the tribe Scapteromyini, first informally described by P. Hershkovitz in 1966 and formally introduced later by E. Massoia in 1979.One of the greatest challenges lying with sigmodontine systematics is that there is much confusion and disagreement amongst authors regarding the relationship between their tribes.In a broad phylogenetic study, Smith and Patton found that the scapteromyine genera Kunsia and Scapteromys formed a clade closely related to the Akodontini.Given the inadequacies of sample size and geographic representation, however, they acknowledged that morphological, karyotypic, and genetic evidence for their separation is unpersuasive.