The genus Abrawayaomys Cunha and Cruz, 1979 (Rodentia: Cricetidae: Sigmodontinae): geographic variation and species definition

Abrawayaomys is a genus endemic to the Atlantic Forest with unique craniodental attributes within the radiation of sigmodontine rodents. Recent data hypothesized the existence of 2 species of Abrawayaomys, namely A. ruschii (from the Brazilian states of Espfrito Santo, Rio de Janeiro, and Sao Paulo) and A. chebezi (from the Argentinean province of Misiones and the Brazilian state of Parana), as well as a possible undescribed species (from the Brazilian state of Minas Gerais). Herein, based on a large series of recently collected specimens, we assessed the congruence between morphologic and molecular characters to search for discontinuities on these features across geography to delimit species within the genus, testing the aforementioned hypothesis. Morphological analyses, both qualitative and quantitative, showed that all characters are polymorphic throughout the geographic range of the genus. Results from phylogenetic analyses of cytochrome b (Cytb) data showed the topology (Misiones (Minas Gerais (Sao Paulo, Rio de Janeiro))), which is better explained as geographic rather than taxonomic variation, based on low values of genetic divergence observed between all specimens. Therefore, we reject the hypothesis of a polytypic Abrawayaomys, synonymizing A. chebezi to A. ruschii, and do not recognize specimens from Minas Gerais state as representing a distinct species.