Oligoryzomys Bangs

Rocha, Rita G., Ferreira, Eduardo, Costa, Barbara M. A., Martins, Iracy C. M., Leite, Yuri L. R., Costa, Leonora P. & Fonseca, Carlos, 2011, Small mammals of the mid-Araguaia River in central Brazil, with the description of a new species of climbing rat, Zootaxa 2789, pp. 1-34 : 20

Oligoryzomys Bangs

Oligoryzomys was the smallest mammal encountered in the area. The dorsal pelage is tawny yellow-brown streaked with black hairs, sides become lighter and the ventral pelage varies from buff to light orange. Heads of both species captured in the study area are grayish and ears are covered by small light hairs. The tail is longer than the head and body length and is self-colored. Hind feet are narrow and very long. Females have four pairs of mammae.

Phylogenetic analyses based on cyt-b sequence data allow us to recognize two species among PEC specimens ( Fig. 10 ). Specimens of O. fornesi form a monophyletic clade, grouping samples from the study area (UFES 1371– 1373 and UFES 1440–1441) and those from the Cerrado areas in the state of Goiás (MN 36746 and MN 36928, Miranda et al. 2009), with an average intraclade divergence of 1.6% among them. The specimen that we treat here as Oligoryzomys sp. groups with O. microtis from state of Amazonas, Brazil (Patton et al. 2000) and from Peru, but with high divergence between them (7.7%). This high divergence probably reflects two distinct species, but with limited samples, we are unable to rule out the possibility of isolation by distance in a geographically structured species. More samples of these species from eastern Amazonia are needed to clarify their taxonomic identities. Nevertheless, our molecular data corroborates previous authors, who found that O. fornesi and O. microtis belong to distinct and divergent evolutionary lineages ( Myers et al. 1995).

Figures

FIGURE 10. Bayesian tree of cyt-b haplotypes from specimens of Oligoryzomys rooted using Hylaeamys and Thomasomys. Bayesian posterior probabilities are in bold and percentages are average Kimura two-parameter distances.