Search

The black lion tamarin, Leontopithecus chrysopygus, is endemic to the Atlantic Forest of the interior of the state of São Paulo in Brazil. Since the discovery of the species, authors have described variations in the pelage of L. chrysopygus, but the nature of this variation has remained unknown. We examined museum specimens and living animals to see if the pelage of L. chrysopygus varies individually, geographically or ontogenetically. We reviewed all known locality records of the species, and concluded that the pelage of L. chrysopygus varies individually and ontogenetically, but not geographically. The extent of the golden chromogenetic fields is larger in younger individuals, and the pelage becomes darker after successive moults. We examined 2 juveniles that presented a pelage similar to adult L. caissara. Geographically, there is a clear break in the phenotypes attributed to L. caissara and L. chrysopygus, precluding clinal variation and corroborating the specific status of the former. The separation between these 2 species is coincident with a tectonic fault known as the ‘Guapiara lineament', and may have been caused by a recent activation of this geological formation. We also suggest a historical contact zone between L. chrysopygus and the marmoset Callithrix aurita in the upper Rio Tietê region.

The ability of a population to evolve in a changing environment may be compromised by human-imposed barriers to gene flow. We investigated the population structure and the possible occurrence of a genetic bottleneck in two isolated populations of the black-faced lion tamarin (Leontopithecus caissara), a species with very reduced numbers (less than 400) in a very restricted range in the Atlantic Forest of southeast Brazil. We determined the genotypes of 52 individuals across 9 microsatellite loci. We found genetic divergence between the populations, each exhibiting low genetic diversity. Analysis revealed broad- and fine-scale population structuring. Both populations have evidently experienced population reduction and a genetic bottleneck without presenting any apparent detrimental effect. Anyway, measures should be taken to effectively protect the forests where L. caissara occurs in order to allow its populations to increase and counteract the eventual effects of genetic impoverishment.

A survey of craniodental variability of the three allopatric populations of Leontopithecus reveals that they are morphologically heterogeneous and individually distinctive, with a nonclinal distribution of characters and pattern similarities. These observations correspond with their better known, starkly different coat coloration, and imply important ecological-adaptive differences. Leontopithecus chrysomelas contrasts markedly in its robust physique, relatively massive and anatomically modified incisors, comparatively small cheek teeth and unique cranial shape. Leontopithecus rosalia is smallest and most gracile, with a highly abbreviated premaxilla and reduced anterior dentition. Leontopithecus chrysopygus is quite the largest in most bodily and cranial dimensions yet is more similar to Leontopithecus rosalia in anterior tooth size and proportions, and has a massively built face. Phyletically, Leontopithecus is most closely related to Callithrix (incl. Cebuella) among the callitrichines. Protection of their habitats is urged for there are three times as many species of endangered Lion Tamarins as we had thought.

Three different arch displays are described in captive lion tamarins (Leontopithecus rosalia rosalia) at the National Zoological Park. Analysis of social behaviours including huddling, sexual activity, territorial encounters and arch displays suggests that arch displaying is motivated by conflicting tendencies of a nonaggressive nature and may function as a regulator of social contact, thus maintaining homeostasis within and between a social group.