Chromosomes of the tan-handed titi (Callicebus torquatus, Hoffmannsegg, 1807).

Two new specimens of Calicebus torquatus confirm the previously reported unusually low diploid number of 2n = 20. Banding studies and radioautography identify the X chromosome and compare the karyotype with that of Callicebus moloch cupreus. The latter species has considerably less C-banded heterochromatin. A comparison of Giemsa bands establishes only few comparable chromosome segments.