New data on the distribution and phylogenetic position of Mastomys awashensis (Rodentia, Muridae)

Abstract

M. awashensis Lavrenchenko, Likhnova, and Baskevich, 1998, is the last species to be described for the genus Mastomys Thomas, 1915. It is apparently confined to the Upper Awash Valley, in an area no wider than 15000 km (Musser and Carleton 2005; Lavrenchenko and Corti 2008). Differently from other species of the genus Mastomys, very few data are available for this species and its systematic relationships remain unclear. Furthermore, this species is currently listed as ‘‘Vulnerable’’ in the IUCN Red List (Lavrenchenko and Corti 2008) due to the lack of data concerning its distribution. M. awashensis shares the same chromosomal formula as M. natalensis but differs in that it has no large heterochromatic blocks (Lavrenchenko et al. 1998). Moreover, the karyotype of M. awashensis has considerably more metacentric elements in the group of large autosomes compared to M. natalensis. Finally, the Y chromosome in M. awashensis is a mediumsized chromosome while it is a large acrocentric in M. natalensis. On the basis of allozymic and morphometric data, Lavrenchenko et al. (1998) highlighted that