Descripción: “...In the torquatus group there were no detectable differences between a “lugens” phenotype from Florencia, Caquetá and a C. t. lucifer from the Colombian trapezium (both were 2n=20), increasing the distribution of the species with that karyotype in the Colombian Amazon.Although initially we supposed that C. lugens (2n=16) was not present in the Colombian Amazon, the discovery of a C. lugens (2n=16) in the Matacaña Zoo strongly suggests the presence of this species in the Colombian Orinoco, although this must be confirmed with field studies.Based on our results a discussion of the evolutionary process in chromosomes is presented for this monogamous, territorial primate genus and some hypotheses regarding the evolution of this group are proposed.Key Words: karyotype, chromosome evolution, Callicebus, cytotaxonomy. ...”