Subspecific morphological variation in the saddle-back tamarin (Saguinus fuscicollis).

Hershkovitz (Living New World, Volume 1. Chicago, University Press of Chicago, 1977, pp. 618-627, 634-666) identified 13 subspecies of Saguinus fuscicollis based on coat color variation on the head, neck, and shoulders. Other morphological differences among the subspecies are unknown. It has been suggested, however, that several of the taxa may be distinct at the specific level. In this report, we examine the level and pattern of facial morphological variation among the subspecific populations to evaluate their taxonomic status. Eleven facial measurements were recorded from the left side of 104 saddle-back tamarin crania. Significant morphological variation among the subspecies in facial heights and depths was detected with discriminant function analysis. Analyses of morphological differences between subspecies and among individual specimens relative to geographical and evolutionary distances (based on the metachromatic theory) were performed by using quadratic assignment procedures. These analyses indicate an absence of geographically related morphological variation across the species range while phylogenetic relationships are reflected in morphological similarities among groups and individuals. This finding is consistent with the formation of subspecific populations by relatively small founding populations budding off from a larger parent population, invading a new interfluvial basin, and then remaining relatively isolated, as suggested by Hershkovitz (Living New World Monkeys, Volume 1. University of Chicago Press, Chicago, 1977).