The golden-backed uakari (Cacajao melanocephalus) or black-headed uakari, is a New World primate from the family Pitheciidae. It lives in the Amazon Rainforest, and is found in the countries of Brazil, Colombia, and Venezuela. It has black hair covering its body, except for a reddish abdomen, tail, and upper limbs, and a bald face. It has highly specialised teeth which allow it to eat seeds and fruits with hard shells. The name golden-backed uakari is a neotype proposed by Boubli et al. (2008). Taxonomy The species Cacajao melanocephalus was previously named the black-headed uakari and two subspecies were thought to exist: Cacajao melanocephalus melanocephalus (black-backed uakari) and Cacajao melanocephalus ouakary (golden-backed uakari). However, in 2008 a new black uakari was discovered and the species group was reassessed by Boubli et al. using morphological and molecular analyses. Cacajao melanocephalus ouakary was found to be a junior synonym of Cacajao melanocephalus but its common name, golden-backed uakari, replaced the previous one, black-headed uakari. Cacajao melanocephalus melanocephalus was elevated to species status as Cacajao hosom (the Neblina uakari), and the new species was named Cacajao ayresi (Aracá uakari). In 2014 Ferrari et al proposed an alternative taxonomy which recognizes the Aracá uakari as a subspecies of the Golden-backed uakari, and also recognized Cacajao ouakary as a separate species from C. melanocephalus, but this revision is not universally accepted. Description The golden-backed uakari is characterized by a black haired head, black hairless facial skin, black lower limbs and hands, black soles on hands and feet, and a reddish hued flank, tail, and upper limbs. They are noted for having a particularly short and non-prehensile tail and highly specialized teeth. Sexual dimorphism is present, with females being slightly smaller than the males, having a mass generally less than 3 kg compared to an overall species' mass ranging from 2.5 to 3.7 kg. Distribution It is native to north-western Brazil, south-eastern Colombia and south-western Venezuela, living in the Amazon Rainforest, especially in the seasonally flooded forests called igapos. No boundaries have been identified between the habitats of the three subspecies. Uakaris are known to travel several kilometers with the changing season in pursuit of certain fruits. Black-headed uakaris have been sighted in varying habitats apart from the igapos, including terra firme, palm swamps, low open white sand forests, rain forests, and campinarana. Diet These uakaris mainly feed on seeds and fruits, but will also eat leaves,