KARYOTYPE OF CALLITHRIX-MAUESI (CALLITRICHIDAE, PRIMATES) AND ITS RELATIONS WITH THOSE OF C-EMILIAE AND C-JACCHUS

A study was conducted on the most recently described marmoset species, Callithrix mauesi, and the results obtained were compared to those pr eviously reported for the karyotypes of C. jacchus and C. emiliae. No mechanism of chromosome rearrangement differentiates the karyotypes of C. mauesi (2n = 44) and C. emiliae (2n = 44), which diverge from C. j acchus (2n = 46) by a Robertsonian translocation and a paracentric inv ersion. C. mauesi, like C. emiliae, presents telomeric constitutive he terochromatin in various chromosomes, forming large heterochromatic bl ocks in some. This does not occur in C. jacchus, which basically prese nts centromeric constitutive heterochromatin. The karyotype of C. maue si differs from that of C. emiliae only by the amount and distribution of this telomeric constitutive heterochromatin. One of the chromosome s presenting a heterochromatic block in C. mauesi is chromosome X, a f act not previously reported in the Order Primates. The present chromos ome data show that C. mauesi is closer to C. emiliae than to C. jacchu s, in agreement with its inclusion in the C. argentata group. In the p resent paper, we describe for the first time, at the chromosome level, chimerism between fraternal twins of the same sex (XY/XY), with the h eterochromatic block of pair 2 being the marker. (C) 1994 Wiley-Liss, Inc.