AOTUS FROM THE SOUTHWESTERN AMAZON REGION IS GEOGRAPHICALLY AND CHROMOSOMALLY INTERMEDIATE BETWEEN A-AZARAE-BOLIVIENSIS AND A-INFULATUS

We described the karyotypes detected in 23 Aotus specimens captured on Southwestern Amazon region (63-degrees 30'W, 9-degrees 00'S). This re gion should be occupied by A. nigriceps. However, the animals describe d here have a fur pattern and a karyotypes similar to those of A. azar ae boliviensis and A. infulatus. The females presented 50 chromosomes and the males 49 as a consequence of fusion between the chromosome Y a nd an autosome. This sample presented polymorphisms of G- and C-bandin g and NOR-staining. These animals are karyotypically intermediate betw een A. a. boliviensis and A. infulatus. The taxonomy and karyotypic ev olution of these taxa are discussed.