Abstract
The red-handed howler (Alouatta belzebul) is an endemic primate in Brazil, and has been received different nominations according to its area of occurrence, which can be restricted to the north of Piauí, Maranhão and Ceará states (A. b. ululata or A. ululata); occur on the right of the Tapajós river (A. b. discolor or A. discolor); or on the right of the Xingu river with disjunct distribut…