Reviewed Article Folia Primatol 2000;71:387–391 The Time of Divergence between the Two Species of Uacari Monkeys: Cacajao calvus and Cacajao melanocephalus Jean Philippe Boubli a Albert David Ditchfield b a Departamento de Antropologia, Museu Nacional/UFRJ, Rio de Janeiro, and b Mastozoologia Museu de Zoologia, Universidade de Sa ˜ o Paulo, Brazil Received: September 28, 1999 Accepted after revision: June 5, 2000 Dr. Jean Philippe Boubli Departamento de Antropologia Museu Nacional/UFRJ Quinta da Boa Vista S/N Sa ˜o Cristo ´ va ˜o, BR–20940-040 Rio de Janeiro, RJ (Brazil) E-Mail boubli@qal.berkeley.edu ABC Fax + 41 61 306 12 34 E-Mail karger@karger.ch www.karger.com © 2001 S. Karger AG, Basel 0015–5713/00/0716–0387$17.50/0 Accessible online at: www.karger.com/journals/fpr Key Words Amazonia W Cacajao W Chiropotes W Mitochondrial DNA W Pithecia W Pitheciinae W Pleistocene glaciations W Uacaris Abstract It has been suggested in the literature that primates of the genus Cacajao have been restricted to flooded-forest habitats of western Amazonia since their split from the Chiropotes line in the Tertiary. It has been proposed further that the differentia- tion of the two species of this genus, Cacajao melanocephalus and Cacajao calvus, occurred during the Pleistocene period as a result of the fragmentation of the Ama- zon forest and the isolation of populations in these forest fragments or refuges. However, recent evidence has shown that at least C. melanocephalus is not depen- dent on flooded-forest habitats, and molecular analysis of mitochondrial DNA shows that the two species had already differentiated during the Pliocene, thus Pleistocene glaciations do not explain the speciation in Cacajao. Considering that C. melanocephalus and its closest relative, Chiropotes, inhabit terra firme forests, it is suggested that preference for flooded-forest habitats may be an apomorphy in C. calvus. Copyright © 2001 S. Karger AG, Basel Introduction Uacaris (Cacajao), together with bearded sakis (Chiropotes) and sakis (Pithecia), comprise the Pitheciinae, a subfamily of New World monkeys that is characterized by animals that specialize in the consumption of seeds from hard-husked fruits [1–3]. Two species and six subspecies of uacaris are recognized: the black-headed uacaris, Cacajao melanocephalus melanocephalus and C. m. ouakary, and the bald uacaris, Cacajao cal-