PERICENTRIC-INVERSION AND X-CHROMOSOME POLYMORPHISM IN RHIPIDOMYS SP (CRICETIDAE, RODENTIA) FROM BRAZIL

Specimens of Rhipidomys collected in the states of Goias and Sao Paulo were analyzed cytogenetically and three karyotypes were identified, a ll with 2n = 44. A heterozygous pericentric inversion in pair 10, resp onsible for the variation in the fundamental number (FN = 48 and 49), was detected. Three types of X chromosomes were found: a large acrocen tric (Xa) and two large submetacentrics (Xb and Xb+). Comparisons betw een the G-banding patterns of our sample and of animals collected in o ther states allowed the conclusion that fourteen pericentric inversion s are responsible for the karyotypical differences found.