On the Morphological Distinctiveness of Callithrix

The dwarf marmoset, described as Callithrix humilis by van Roosmalen et al. (1998), is an anomaly among Amazonian marmosets for its size, morphology and behavior. We compare cranial and mandibular characters of the dwarf marmoset with representatives of four other callitrichid genera. C. humilis displays qualitative differences in skull morphology when compared to other callitrichids, and a discriminant analysis of quantitative characters suggests that the dwarf marmoset is strongly distinct from all other Amazonian genera, including Callithrix. These differences are most pronounced in the morphology of the lower jaw and may refl ect specialized feeding adaptations, although little is known of the dwarf marmoset’s behavior in the wild.