CHROMOSOMES OF ALOUATTA-SENICULUS (PLATYRRHINI, PRIMATES) FROM FRENCH-GUIANA

Karyotypes of 42 specimens of Alouatta seniculus from French Guiana we re analyzed by G- and/or R-banding, C-banding, and NORs Ag-staining te chniques. The samples were collected during a rescue operation perform ed at the Petit Saut dam site. All studied specimens but one possess d iploid chromosome numbers ranging from 47 to 49, this variation being due to the presence of one to three supernumerary or B-chromosomes (B' s). Males exhibit a Y;autosome translocation involving the short arm o f an individual biarmed autosome, which results in the following sex c hromosome systems: X(1)X(2)Y(1)Y(2) in males and X(1)X(1)X(2)X(2) in f emales. Different degrees of chromosome heteromorphism were observed i n pairs 9, 12, 14, 19, 21, and 22 related with variations in the amoun t of constitutive heterochromatin. Of special interest is the heteromo rphism for pair 7 (X(2)) observed in the females, whereas only one of two variants was constantly found in males. Comparisons with other A. seniculus chromosomal data reported in the literature indicate that Re d Howlers from French Guiana resemble very closely, from a taxonomic p oint of view, A. s. macconnelli from the Jari River (Brazil). These da ta could be used to estimate biodiversity and to reassess taxonomic cr iteria in this group.