Despite many explorations and surveys, the geographic distribution of many primate species, particularly in the neotropics, is not yet well known. In this paper, we provide evidence that extends the range of Spix's saddle-back tamarin in Peru.

As part of our study on coppery titi monkeys in the Peruvian Amazon, we observed an individual rubbing his belly with leaves from a potentially medicinal plant. He climbed down from high above and grabbed a handful of leaves from an understory tree, which made it look like a deliberate action. Sitting on a liana he then chewed on the leaves before rubbing them slowly on his belly for a couple of minutes. The plant genus is known in traditional medicine and is used for various effects.

This paper discusses the status of a tamarin specimen housed at the American Museum of Natural History that is wrongly labelled as Saguinus fuscicollis tripartitus and might represent a species or subspecies unknown so far or a hybrid.