KARYOLOGICAL DIFFERENTIATION OF RATS OF THE GENUS MASTOMYS (RODENTIA, MURIDAE) FROM THE CENTRAL PART OF ETHIOPIAN RIFT-VALLEY

Mastomys rats are represented by three distinct partly sympatric (in the Koka area) karyomorphs in the central part of Ethiopian Rift Valley: 38-chromosomal M. erythroleucus, 32-chromosomal M. huberti, and new 32-chromosomal M. sp. C- and G-banded chromosomes of these Mastomys forms are described. The karyotype of the new 32-chromosonial M. sp. is characterized by the specific mainly pericentromeric autosomal heterochromatin revealed with G-banding, thus being different from the sympatric 32-chromosomal M. huberti, which besides pericentromeric heterochromatin has also significant amount of marked heterochromatin in the additional short arms of 5 autosomes. The distribution of he Mastomys forms is discussed.