SYSTEMATICS AND DISTRIBUTION OF MASTOMYS (MURIDAE, RODENTIA) FROM ETHIOPIA, WITH THE DESCRIPTION OF A NEW SPECIES

Studied was morphological, allozymic, and chromosomal variation of Eth iopian Mastomys natalensis sensu late to clarify the systematics of th is species complex. Three different species of Mastomys occur in Ethio pia. A new species, Mastomys awashensis n. sp., is described and compa red with the other two, M. erythroleucus and M. natalensis which are w idely distributed throughout most of Western, Central, and Eastern Afr ica, Mastomys awashensis n. sp, is endemic to the Ethiopian Rift Valle y and is known only from two localities in the Upper Awash Valley. Thi s newly described species differs from the other two Ethiopian Mastomy s species by fixed alleles at Ldh-B and Got-1 loci and also by Hbb pat terns and by relatively shorter tail bearing smaller scales. Besides t hat, the three species co-existing in the middle part of the Ethiopian Rift Valley can be distinguished biometrically with the use of multiv ariate analysis. The karyotype of M. awashensis (2n = 32, NFa = 54) wh ich is similar to that of M. natalensis, demonstrates, nevertheless, a number of unique characteristics differing it from any known represen tative of the M. natalensis species complex. The presented results fro m different disciplines support a previous supposition of a ''mosaic'' evolution under divergence in this species group.