The karyotype of Brucepattersonius griserufescens Hershkovitz, 1998 (Rodentia, Sigmodontinae) with comments on distribution and taxonomy

We karyotyped three Oxymycterus species (O. hispidus, O. roberti, and O. ca raparoe) and Brucepattersonius griserufescens. B. griserufescens (2n = 52/F N = 52-53) differed from the other three karyologically identical species ( 2n = 54/FN = 64). Furthermore, comparisons of O. hispidus and O. caraparoe G-band karyotypes with data in the literature indicated that these species were karyologically identical with O. roberti, O. angularis, O. rutilans, O xymycterus sp., O. rufus, O. paramensis, O. nasutus, and O. akodontius. Mor phological characteristics allowed the distinction of two consistent groups , one including O. iheringi and B. griserufescens, characterized by reduced claws and a small body size, and another, of typical Oxymycterus species, with well-developed claws and medium or large body size. Finally, our data extended the distribution on the iheringi species group to Rio de Janeiro a nd Espirito Santo states in Brazil.