Philip Hershkovitz’s research while affiliated with Field Museum of Natural History and other places

Thalpomys Thomas, endemic to the cerrado of central Brazil, is a strikingly distinct genus of the akodont assemblage (Sigmodontinae, Cricetidae, Rodentia). The genus and the two included species, one new, are described and compared. The validity of the names of the genus and type species T. lasiotis Thomas, 1916, is elucidated. The little known about habitat, relative population numbers, and karyotype is included.

The proximal portion of a subfossil monkey femur found in a Jamaican cave shares all the femoral characters of a mature male Cebus apella.The fragment alone, however, does not prove conspecificity. The Jamaican femur is also of a size that could belong to the extinct Xenothrix mcgregoriof the same island. In contrast, the distal portion of a monkey tibia recovered from a kitchen midden in the Dominican Republic cannot be identified with that of any known living platyrrhine or catarrhine monkey. Geological age, geographic locality, and size of fragment point to probable alignment of the tibia with the recently extinct cebid Saimiri bernensis.Although no conclusive identifications are made, the distinctive characters of the two limb bones are described on the basis of comparisons with femurs and tibias representing all genera of living platyrrhines, most genera of catarrhine monkeys, and some strepsirhines.

The two known species of uacaries, inhabitants of the upper Amazonian region, are the black head Cacajao melanocephalus with subspecies C. m. melanocephalus Humboldt and C. m. ouakary Spix, and the larger bald head uacari C. calvus with subspecies C. c. ucayalii Thomas, C. c. rubicundus I. Geoffroy and Deville, C. c. calvus I. Geoffroy, and C. c. novaesi described as new. The diagnostic generic characters described are the external, cranial, dental, some postcranial, and cytogenetic. The species are described and compared and their geographic distribution plotted with those of their subspecies delimited. Sexual differences are outlined. Apart from size-related characters, the species and subspecies are distinguished by pelage pattern of head and coloration in general. It is shown that both species could have diverged from a hairy-headed melanistic ancestral form. Pelage divergence in the descendants was expressed by the more pilose head of C. melanocephalus, and less pilose of C. calvus. Coloration differentiation was geographic and followed metachromic lines with mutation from eumelanism to partial pheomelanism (reddish or golden) in C. melanocephalus and to virtually complete pheomelanism in C. calvus. The subspecies of each species are distinguished by color patterns resulting from selective bleaching or dilution of the pheomelanin fields. The most saturate pheomelanic subspecies of C. calvus is C. c. ucayalii and the most dilute is the albinotic C. c. calvus. Correlation between coloration and environment is not evident. A gazetteer identifies all locality records plotted by numbers on the geographic distribution maps.

The report begins with a key based on external characters and a tabulation of diagnostic cranial characters for separating Pithecia from Chiropotes and Cacajao of the subfamily Pitheciinae. The description of Pithecia is based on external, cranial, dental, and certain postcranial characters with particular attention to limb proportions and the femoral third trochanter. The species of Pithecia are arranged in the Pithecia pithecia group with P. p. pithecia and P. p. chrysocephala, and the Pithecia monachus group with P. m. monachus, P. m. milleri, P. irrorata irrorata, P. i. vanzolinii (new subspecies), P. aequatorialis (new species), and P. 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] as Pithecia monachus proves to be the new species P. aevuatorialis, whereas the sympatric species he called P. hirsut Spix (1823)s the same as true P. monachus É. 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 of Pithecia is 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 forms Pithecia aequatorialis and P. irrorata vanzolinii. Comparable descriptions of all taxa are contained in Volume 2 of Living New World Monkeys, currently in preparation. The gazetteer, however, includes complete data for all saki collecting and recorded localities plotted on the range maps.

Two groups of squirrel monkeys, genus Saimiri, are distinguished by external characters. The first, or Roman type, contains Saimiri boliviensis of upper Amazonia south of the Rio Marañón-Amazonas, with two subspecies of which S. boliviensis peruviensis is described as new. The second group, or Gothic type, contains three species: Saimiri sciureus with four subspecies distributed over much of tropical South America, Saimiri ustus of Brazil between the south bank Amazonian Rios Purús and Xingu, and S. oerstedi isolated on a Pacific coastal area straddling Costa Rica and Panamá. The geographic range of S. sciureus overlaps parts of those of S. ustus and S. boliviensis. Incomplete karyotypic data indicate that the diploid number of chromosomes for the genus is 44. Geographic variation is characterized by reduction from seven to six or five paired acrocentric autosomes through pericentric inversion with reciprocal increase in number of paired submetacentric or subtelocentric autosomes. Geographic distribution, behavior, sexual dimorphism including dichromatism, and hybridization are discussed. Ventral guide hairs for orientation of subprecocial newborn toward the maternal mammae are described. Distinguishing characters of species and subspecies are provided in a key. The taxons are listed with the taxonomy of each discussed, their geographic distribution plotted and mapped.

Two groups of squirrel monkeys, genus Saimiri, are distinguished by external characters. The first, or Roman type, contains Saimiri boliviensis of upper Amazonia south of the Rio Marañón‐Amazonas, with two subspecies of which S. boliviensis peruviensis is described as new. The second group, or Gothic type, contains three species: Saimiri sciureus with four subspecies distributed over much of tropical South America, Saimiri ustus of Brazil between the south bank Amazonian Rios Purús and Xingu, and S. oerstedi isolated on a Pacific coastal area straddling Costa Rica and Panamá. The geographic range of S. sciureus overlaps parts of those of S. ustus and S. boliviensis. Incomplete karyotypic data indicate that the diploid number of chromosomes for the genus is 44. Geographic variation is characterized by reduction from seven to six or five paired acrocentric autosomes through pericentric inversion with reciprocal increase in number of paired submetacentric or subtelocentric autosomes. Geographic distribution, behavior, sexual dimorphism including dichromatism, and hybridization are discussed. Ventral guide hairs for orientation of subprecocial newborn toward the maternal mammae are described. Distinguishing characters of species and subspecies are provided in a key. The taxons are listed with the taxonomy of each discussed, their geographic distribution plotted and mapped.

The little-worn deciduous fourth premolar and first molar of a mandibular fragment of Homunculus sp are compared with the cast of a previously described deciduous lower fourth premolar of Homunculus grandis and with lower molariform teeth of Alouatta and Stirtonia. Lower molars of Alouatta can be derived from those like Homunculus, but because of the fragmentary nature of the fossils, it cannot be demonstrated that Alouatta evolved from Homunculus or is even closely related. Comparison of mandibles and upper and lower molariform teeth of Alouatta with those of Stirtonia indicate wide divergence from some distant, possibly basic platyrrhine stock.

The nine allopatric species of Aotus recognized represent two natural groups distinguished by karyotype, color, and pelage patterns. Correlated with these group characters are reported differences in serum proteins and degrees of susceptibility or immunity to experimental infection with malarial parasites. The primitive gray-neck species group of Aotus contains A. brumbacki (new species), A. lemurinus (with subspecies lemurinus and griseimembra), A. trivirgatus, and A. vociferans. The derived red-neck group contains A. nancymai (new species), A. miconax. A. infulatus, and A. azarae (with subspecies azarae and boliviensis). Only the two new species are described but a key to the species and subspecies gives the diagnostic characters of each. The gray-neck group occurs almost entirely north of the Amazon, the red-neck group almost entirely south. The distributional exceptions are enclave populations resulting from river bend cutoffs. Formation of an enclave population of A. nancymai is discussed and available information on the biology of this species is reported.