The taxonomy of south American sakis, genusPithecia(Cebidae, Platyrrhini): A preliminary report and critical review with the description of a new species and a new subspecies

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Abstract
The report begins with a key based on external characters and a tabulation of diagnostic cranial characters for separatingPitheciafromChiropotesandCacajaoof the subfamily Pitheciinae. The description ofPitheciais based on external, cranial, dental, and certain postcranial characters with particular attention to limb proportions and the femoral third trochanter. The species ofPitheciaare arranged in thePithecia pitheciagroup withP. p. pitheciaandP. p. chrysocephala, and thePithecia monachusgroup withP. m. monachus, P. m. milleri, P. irrorata irrorata, P. i. vanzolinii(new subspecies),P. aequatorialis(new species), andP. albicans. The discussion on nomenclature compares the usage of names by various authors for the different taxa. The species previously identified by Hershkovitz [Hershkovitz, 1979] asPithecia monachusproves to be the new speciesP. aevuatorialis, whereas the sympatric species he calledP. hirsutSpix (1823)s the same as trueP. monachusÉ. Geoffroy (1812). Speciation among sakis is expressed, for the most part, by marked differentiation in coloration and head pelage patterns in males. Females of corresponding males diverged along the same lines but to such lesser degree that specific discrimination between them is complicated. Details of sexual dimorphism in coloration and pelage patterns are described, and those of size are documented by summaries of weights and by measurements of external, cranial, dental, and skeletal characters for each sex of each taxon. A key to the species and subspecies ofPitheciais followed by an account of each taxon that includes statements of taxonomic history or synonymy, type specimen, type locality, and geographic distribution. A full description with the addition of accounts of diagnostic characters, variation, comparisons, measurements, list of specimens examined, and other matters, is provided only or the new formsPithecia aequatorialisandP. irrorata vanzolinii. Comparable descriptions of all taxa are contained in Volume 2 ofLiving New World Monkeys, currently in preparation. The gazetteer, however, includes complete data for all saki collecting and recorded localities plotted on the range maps.