The monkey, called "lesula" by locals, was discovered in June 2007 in the Congo when field scientists spotted a female that had been adopted by a primary school director.
The species has been given the scientific distinction Cercopithecus lomamiensis. Researchers say it is closely related to the owl-faced monkey (Cercopithecus hamlyni), which is also indigenous to the region.
Since the initial find, wild lesula have been spotted in the Congo, usually in small groups.
The species is characterized as a "shy" and "quiet" herbivore that lives in remote forests.
Lesulas are well-known to local hunters, and researchers warn that uncontrolled hunting practices could quickly lead to the species' "catastrophic decline".
The findings have been published in PLOS One.