The Black-tailed Marmoset (Mico melanurus) is a species from central South America, where ranging from the south-central Amazon in Brazil, south through the Pantanal and eastern Bolivia, to the Chaco in far northern Paraguay.
It is dark brown with paler foreparts and a black tail. Unlike most of its relatives, it has a striking white or yellow-white stripe that extends down its thigh. Its ears are naked, flesh-colored, and stand out from the fur.
Black-tailed Marmosets are diurnal and arboreal, using their claws to climb trees. Originally rain forest inhabitants, plantations have caused them to expand their range. They spend the night in tree hollows or in very close vegetation. They live together in small groups and mark their territory with scent glands, driving out intruders by shouting or by facial expressions, including lowered brows and guarded lips.
The diet of the black-tailed marmoset predominantly consists of tree sap. To a lesser extent, they also eat bird eggs, fruits, insects, and small vertebrates.