-SIGMODONTINE RODENTS (RODENTIA, CRICETIDAE) FROM QUATERNARY CAVE DEPOSITS OF SERRA DA CAPIVARA, NORTHEASTERN BRAZIL. The Serra da Capivara National Park, State of Piauí, Brazil, and surrounding areas preserves a rich archeological and paleontological record of South American mammals. It includes a great amount of sigmodontine rodent remains recovered from limestone caves and rock shelters. We studied sigmodontine material from three caves, named Toca do Gordo do Garrincho, Toca do Barrigudo, and Toca do Serrote das Moendas, and identified the following taxa: Bibimys sp., Necromys lasiurus, Pseudoryzomys simplex, Holochilus sciureus, Cerradomys sp., Calomys sp., and Wiedomys sp. This is the first record of Bibimys for the Quaternary of northeast Brazil, which suggests that the paleobiogeographic distribution of this genus was different from its currently known range. Thus, we contribute to the knowledge of Quaternary sigmodontine rodents through these new taxonomic records and highlight the great potential of Serra da Capivara paleontological deposits for clarifying the biogeographic dynamics of this group during this period. Key words:Bibimys, Pleistocene, Holocene, caves, mammals, paleobiogeography.RESUMO -Na região do Parque Nacional Serra da Capivara, Estado do Piauí, Brasil, conhecida pelas descobertas arqueológicas e paleontológicas, numerosos restos de roedores Sigmodontinae foram recuperados de grutas e abrigos calcários. O material aqui estudado provém de três cavernas da região: Toca do Gordo do Garrincho, Toca do Barrigudo e Toca do Serrote das Moendas. Foram identificados os táxons Bibimys sp., Necromys lasiurus, Pseudoryzomys simplex, Holochilus sciureus, Cerradomys sp., Calomys sp. e Wiedomys sp., sendo o registro de Bibimys inédito para o Quaternário do nordeste brasileiro, sugerindo uma distribuição paleobiogeográfica diferente da atualmente conhecida para este táxon. Assim, contribuímos para o conhecimento dos sigmodontíneos do Quaternário do Brasil com novos registros do grupo para a Serra da Capivara, mostrando que os materiais recuperados na região apresentam grande potencial para fornecer esclarecimentos sobre a dinâmica biogeográfica destes roedores ao longo do Quaternário.

The rare cricetid rodent Bibimys Massoia, 1980 contains three extant species that are distributed in the lowlands of eastern South America between 35°S and 20°S and distinguished mostly by subtle morphological and genetic features. Several fragmented jaws belonging to this genus were recovered from Late Quaternary deposits located in northeastern Brazil, forming part of a rich archaeological and paleontological small mammal assemblage that has been recovered from caves in the Serra da Capivara, state of Piauí. This material is described herein as belonging to a new species, the most hypsodont member of the genus. The specimens also represent an extralimital occurrence of this sigmodontine, as the nearest extant population of Bibimys is ~1,200 km to the south. Because there are few reliable records of extinct small mammals from the Pleistocene–Holocene transition on the South American continent, in describing this new sigmodontine we extend the records of past biodiversity preserved in the Quaternary deposits of tropical South America. This new species likewise highlights that the Serra da Capivara deposits are promising for understanding the evolutionary history of cricetid rodents.