The bare-eared squirrel monkey (''Saimiri ustus'') is a

squirrel monkey Squirrel monkeys are New World monkeys of the genus ''Saimiri''. ''Saimiri'' is the only genus in the subfamily Saimiriinae. The name of the genus is of Tupi origin (''sai-mirím'' or ''çai-mbirín'', with ''sai'' meaning 'monkey' and ''mirím' ...

endemic to

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

and possibly eastern

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

References

Endemic mammals of Brazil Primates of Brazil Squirrel monkeys Mammals described in 1843 Taxa named by Isidore Geoffroy Saint-Hilaire {{newworld-monkey-stub