Comparative chromosome morphology in three Callitrichid genera: Cebuella, Callithrix, and Leontopithecus

A G-band karyotypic analysis was carried out in individual species groups of three Callitrichid primate genera: Cebuella, Callithrix, and Leontopithecus. Within Callithrix, the karyotypes of the morphologically distinct and geographically isolated morphotypes C. jacchus jacchus and C. jacchus penicillata were identical. Within the lion tamarin genus, Leontopithecus, the karyotypes of the three morphotypes (L. rosalia rosalia, L. rosalia chrysomelas and L. rosalia chrysopygus) were also indistinguishable from one another. These results are consistent with the taxonomic designation of subspecies rank to the different morphotypes. A comparison of type specimens among the three Callitrichid genera showed that their phyletic radiation has been paralleled by a limited number of chromosome rearrangements and a relatively high amount of karyotypic invariance. A fusion/fission event has been postulated to account for the difference in diploid number between Cebuella (2n = 44) and the other species (2n = 46). The karyotype of Callithrix jacchus was found to be more directly derived from Cebuella than was that of Leontopithecus. These findings differ from the previous proposition that Leontopithecus might have diverged from a common Callitrichid ancestor before the emergence of the genus Callithrix.