Titi monkeys (Callicebus spp., Atelidae : Platyrrhini) in the Brazilian state of Rondonia

Five species of titi monkey (Callicebus brunneus, Callicebus caligatus, Cal licebus cinerascens, Callicebus donacophilus, and Callicebus moloch) were r ecorded in surveys of primate populations at 26 sites throughout the Brazil ian state of Rondonia. The distribution of the two species, C. cinerascens and C. donacophilus (recorded in the state for the first time), appeared to be related to that of non-forest ecosystems, the former in the cerrado woo dlands, and the latter in gallery forests of the Guapore grasslands. The re sults of the surveys also indicate that C. brunneus has a more restricted d istribution in southern Rondonia than was previously thought, whereas C. mo loch is more widespread. However, the ecological factors that determine spe cies distribution in the south of the state remain unclear on the basis of the available data. All species were observed in small social groups of no more than five individuals, which are typical of the genus, generally in th e middle and lower forest strata.