Researchers have identified and formally described a new species of the African monkey genus Colobus living in the remote interior of the Democratic Republic of Congo, marking only the fifth new monkey species found on the continent in the past 75 years.
Colobus congoensis. Image credit: Daniel Rosengren, Frankfurt Zoological Society.
The newly described species is a small, black-furred monkey distinguished by a striking orange-cream patch around its mouth and nose, set against an otherwise black, mask-like face, along with a prominent white patch near its tail.
Named Colobus congoensis, the primate inhabits the eastern basin of the Lomami River and adjacent basin of the Upper Congo (Lualaba) River, Democratic Republic of Congo.
“This discovery is both exciting and deeply personal, highlighting the extraordinary biodiversity of my homeland and how much remains undocumented,” said Junior Amboko, a Ph.D. student at Florida Atlantic University.
“I was honored to name the species Colobus congoensis, recognizing the Congo Basin’s remarkable natural heritage and, we believe, marking the first primate named after the Democratic Republic of Congo itself — underscoring both its global importance and local pride.”
Colobus congoensis was first captured on camera in 2008 by researchers exploring the Lomami Basin, though its significance wasn’t recognized at the time.
It wasn’t until 2018, when a park ranger photographed the animal again and noted its unusual markings, that scientists began investigating in earnest.
Over the following months, park rangers documented the monkey repeatedly across the region, and Amboko and colleagues eventually matched those sightings to the decade-old photograph.
Despite living near several villages, the monkey turned out to be almost unknown to local communities — only 8 of 52 villages surveyed near its range could accurately describe it, in sharp contrast to residents’ familiarity with other local primates.
“The discovery of Colobus congoensis is reshaping our understanding of African monkey evolution,” said Dr. Kate Detwiler, also from Florida Atlantic University.
Genetic and skeletal analysis revealed that Colobus congoensis is most closely related to the Black colobus (Colobus satanas), a monkey found more than 1,200 km away in west-central Africa and on Bioko Island.
Mitochondrial DNA suggests the two lineages diverged roughly 4 to 5 million years ago, making it the deepest split between sister species anywhere in the Colobus genus.
The researchers also found that the new species’ calls share structural similarities with those of its distant relative, though with distinctive differences in pitch and pattern.
“We compared the skulls and pelts of Colobus congoensis with other species of African colobines, which underscored how unique this new species is,” said Dr. Julia Arenson, a researcher at Yale University.
“At the same time, despite being much smaller in body size, we also demonstrated it shares features of the teeth, skull and face with Colobus to the exclusion of other African colobines.”
“In order to name a new species, you have to be able to prove it,” said City University of New York’s Professor Christopher Gilbert.
“We used extensive museum collections including specimens housed at the Yale Peabody Museum and the American Museum of Natural History, and comparative datasets to compare the skulls and pelts with known African colobus monkeys.
“This robust pool of information allowed us to pretty quickly and conclusively confirm Colobus congoensis as a new species.”
Field surveys conducted between 2018 and 2022 recorded 114 sightings of Colobus congoensis across an estimated range of just 1,700 km2 — strikingly small compared to the ranges of other Colobus species, some of which exceed 60,000 km2.
The animals were typically seen in small groups averaging about six individuals, often traveling alongside other monkey species in the forest canopy.
The scientists propose a preliminary IUCN Red List classification of Endangered for Colobus congoensis based on its small range area and population size.
“We continue to be reminded that the Congo Basin remains one of the world’s last great frontiers for mammal discovery,” said Dr. John Hart, a conservation scientist with the Lukuru Wildlife Research Foundation.
“Even in regions that have been scientifically explored, entirely new species are still coming to light.”
“This discovery reinforces how much biodiversity remains undocumented in the Central Congo Basin and how this region continues to reshape our understanding of primate evolution and conservation.”
The discovery is reported in a paper in the journal PLoS ONE.
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J.A. Hart et al. 2026. Likweli: A remarkable new species of Colobus monkey from the Lomami National Park, Democratic Republic of Congo. PLoS One 21 (7): e0349857; doi: 10.1371/journal.pone.0349857
