RESUMEN
We assessed the genetic diversity of two northern muriqui (Brachyteles hypoxanthus Primata, Atelidae) populations, the Feliciano Miguel Abdala population (FMA, n = 108) in the Brazilian state of Minas Gerais (19°44' S, 41°49' W) and the Santa Maria de Jetibá population (SMJ, n = 18) in the Brazilian state of Espírito Santo (20°01' S, 40°44' W). Fecal DNA was isolated and PCR-RFLP analysis used to analyze 2160 bp of mitochondrial DNA, made up of an 820 bp segment of the gene cytochrome c oxidase subunit 2 (cox2, EC 1.9.3.1), an 880 bp segment of the gene cytochrome b (cytb, EC 1.10.2.2) and 460 bp of the hypervariable segment of the mtDNA control region (HVRI). The cox2 and cytb sequences were monomorphic within and between populations whereas the HVRI revealed three different population exclusive haplotypes, one unique to the SMJ population and two, present at similar frequencies, in the FMA population. Overall haplotype diversity (h = 0.609) and nucleotide diversity (pi = 0.181) were high but reduced within populations. The populations were genetically structured with a high fixation index (F ST = 0.725), possibly due to historical subdivision. These findings have conservation implications because they seem to indicate that the populations are distinct management units.