Rhipidomys Tschudi

Rhipidomys Tschudi

The genus Rhipidomys is one of the least known arboreal mammals of the Neotropics (Tribe 2005) and Patton et al. (2000) suggests that species of this genus are either difficult to trap or generally uncommon in Amazonia. Knowledge on Rhipidomys from central Brazil is even sparser. Species of this genus from states of Pará and Mato Grosso were allocated by Tribe (1996) to R. nitela and R. emiliae, and treated only as R. nitela by Costa (2003). According to Voss et al. (2001), R. nitela is confined to Amazonia, east of the Negro and Madeira Rivers.

During this study, 24 specimens of Rhipidomys were captured, and thorough comparisons of morphological characters (detailed below) and molecular analyses allow us to recognize a new species within this genus. This new species is genetically distinct in terms of mtDNA sequences, and represents a well-supported clade (Fig. 13). It shows an average genetic divergence of 5.1% to its sister species, R. emiliae from states of Pará and Mato Grosso, and an average divergence of 9.5% to R. nitela from French Guiana, the species to which it was previously assigned (Costa 2003). Clades of R. mastacalis and R. leucodactylus correspond to the same of those from the previous work of Costa (2003), and the clade of R. cariri correspond to a topotype captured at Crato, state of Ceará, type locality of this species (Tribe 2005). Rhipidomys sp. 2 and R. sp. 3 (Fig. 13) are currently being described (Costa et al. in press).