Comparative chromosomal study of five taxa of genus Callithrix, group jacchus (Platyrrhini, Primates).

The karyotypes of four marmoset species of the Callithrix jacchus group (C. aurita, C. kuhlii, C. geoffroyi, and C. penicillata) were investigated. The patterns of G-, C-, and NOR-bands of these karyotypes were compared with those of C. jacchus, previously described, in order to clarify the taxonomic relationships of this species group. All species present 2n = 46, 14 uni- and 30 biarmed autosomes, a median size submetacentric X chromosome, and the same NOR-band patterns. No rearrangement or constitutive heterochromatic variation differentiate these species, which differ only in the morphology of the Y chromosome. The data obtained indicate that, from the chromosomal point stand, the marmoset species of C. jacchus group constitute a homogeneous clade.