Chromosomal banding patterns in Akodon arviculoides (2n=14),Akodon sp.(2n=24 and 25), and two male hybrids with 19 chromosomes.

Chromosomal polymorphism resulting from two pericentric inversions in Akodon arviculoides (2n=14) has been described (YONENAGA, 1972a). In this paper the banding patterns are presented and identification of the inverted segments of the autosomal pairs 2 and 3 is made. The karyotype of Akodon sp., which varies in diploid number (2n-24 and 25), is described and shown to be due to the presence of a small submetacentric chromosome in the 2n=25 individuals. The karyotypes of two 2n=19 males studied show that they are hybrids between Akodon arviculoides (2n=14) and Akodon sp. (2n=24).