A new karyotype in Callicebus torquatus (Cebidae, Primates)

We describe a new karyotype of Callicebus torquatus using conventional stai ning, G-banding with Wright Stain, CBG. Ag-NOR staining and fluorescence in situ hybridization (FISH) with human telomere probes and comparative analy sis with the previously reported karyotype of C. torquatus torquatus (2n = 20). We studied a Female specimen maintained in captivity at the Centro Nac ional de Primatas (Para, Brazil). This titi monkey presented Zn = 22, with Four large biarmed and six acrocentric autosome pairs: the X chromosome is a medium submetacentric. C-bands were revealed at the centromeric region of all acrocentrics and X chromosome; punctual C-bands also are visualized at the centromeric region in the large biarmed pairs. The NOR site was locate d at the long arm of pair 4, at the position of a conspicuous secondary con striction. Hybridization signals were detected exclusively at the terminal region of all chromosomes. The karyotype described here has one acrocentric pair more than that found in the literature and also differs by amount and distribution of constitutive heterochromatin. Our data support the notion that the torquatus group may be composed of distinct species, each with its own karyotype.