M. Weksler et al., Status of Proechimys roberti and P-oris (Rodentia : Echimyidae) from eastern Amazonia and central Brazil, J MAMMAL, 82(1), 2001, pp. 109-122
Proechimys roberti has been considered an isolate representative of the guy
annensis group of species of the genus Proechimys in the Cerrado of central
Brazil, or regarded as a member of the longicaudatus group of species. We
present new karyologic, morphometric, morphologic, and molecular data from
populations spanning the gap between the previously known isolated distribu
tion of P. roberti and the core distribution of the guyannensis group. All
specimens had the same basic karyotype, 2n = 30, with fundamental number (F
N) = 54-55. FN variation was due to a pericentric inversion affecting a sma
ll autosomal pair. Specimens from the eastern Amazon Basin and the Cerrado
did not have any differentiation in external, cranial, and dental character
s. In contrast, samples showed a significant multivariate morphometric vari
ation, with a high heterogeneity among all populations, independent of Cerr
ado or Amazon location. Our results, coupled with phylogenetic analysis of
cytochrome-b sequences, indicate that P. roberti is a valid species of the
guyannensis group and that the species of this group occurring in eastern A
mazon, P. oris, is probably a junior synonym of P. roberti.