Researchers have identified a new type of African monkey - only the second such discovery in the last 28 years.
The Cercopithecus lomamiensis, or lesula, was first found in June 2007 in the Democratic Republic of the Congo. Research teams came across the young lesula which had been adopted by the daughter of school director in the small town of Opala.
While the young monkey looked similar to the owl-faced monkey, its colouration was like no other known species.
Researchers from the Democratic Republic of the Congo and the United States found more of the monkeys in the wild, deep in the Lomami forest basin. They determined it was genetically and anatomically distinct from other species.
The researchers described the lesula as a "medium sized, long-limbed monkey with a slender body".
The male "exhibits a bright blue scrotum and perineum", and "emits a characteristic low frequency, descending, loud call or boom," they wrote.
The scientists said the discovery is only the second identification of a new African monkey species in 28 years.
Their findings have been published today in the online journal PLOS One.
The researchers said the lesula is "not uncommon" in its habitat, an area of at least 17,000km2. However, it was probably unknown because the area has not been explored until recently.
In 19 encounters with the new species, 48 individuals were observed.
While the lesula's habitat is not currently at risk from logging or mining, the researchers said the region "urgently requires controls on hunting along with the creation of a protected area".
"The challenge for conservation now in Congo is to intervene before losses become definitive," Yale Peabody Museum of Natural History researcher John Hart said.
"Species with small ranges like the lesula can move from vulnerable to seriously endangered over the course of just a few years."