Scientists Confirm a Striking New Monkey Species Hidden in the Congo Rainforest

A monkey science almost missed

Deep in the forests between the Lomami and Congo river systems in the Democratic Republic of Congo, researchers have formally described a previously unknown species of African monkey. Named Colobus congoensis and known locally as Likweli, it has glossy black fur, a long tail and a striking orange-cream patch around its mouth and nose.

The description, published in PLOS One on July 15, 2026, is unusually significant. It is only the fifth new African monkey species described in 75 years—an uncommon event in a mammal group that has been studied for centuries.

From a blurred photograph to a formal species

The first clue appeared in 2008, when an expedition obtained a partially obscured photograph of an unfamiliar monkey. A clearer encounter in 2018 triggered years of targeted surveys. Between 2018 and 2022, teams recorded 114 detections within an estimated range of just 1,700 square kilometres.

Formal recognition required more than unusual colouring. The researchers compared museum skulls and skins, recorded the animals’ calls, analysed mitochondrial DNA and documented their habitat and behaviour. The genetic, morphological and acoustic evidence converged on the conclusion that Likweli represents a distinct evolutionary lineage.

A relative separated by 1,200 kilometres

Likweli’s closest known relative is the black colobus, Colobus satanas, which lives more than 1,200 kilometres away in west-central Africa. Molecular dating suggests their lineages separated roughly four to five million years ago, one of the oldest splits recognized within the genus.

The new species is smaller than many related colobus monkeys, weighing around 15 pounds. Its mask-like face combines orange-cream skin around the mouth with grey cheek areas and black skin around the eyes. Its deep roaring calls resemble those of the black colobus but have a distinct acoustic structure.

Local knowledge completed the picture

Scientists also interviewed residents and hunters around Lomami National Park. People in only eight of 52 surveyed localities could accurately describe the animal, evidence of how rare and geographically restricted it is. The name Likweli comes from communities bordering its range; another local name means “branch shaker.”

This was not a story of outsiders discovering an animal that everyone nearby already knew well. Instead, field science, museum collections, genetics and limited local knowledge supplied different pieces of an elusive biological puzzle.

Discovered—and possibly already endangered

Most observations came from mature, high-canopy forest near the Lomami River. Groups averaged about six animals, and sightings were sparse despite thousands of kilometres of survey effort. The authors propose a preliminary Endangered classification because of the small known range and population, dependence on old-growth forest, hunting pressure and continuing habitat conversion.

That status is a scientific proposal, not yet a final IUCN Red List assessment. The true population size is also unknown: rarity in surveys can reflect low abundance, elusive behaviour, uneven search coverage or a combination of all three.

Why the discovery matters

Likweli expands the known diversity and evolutionary history of African colobus monkeys. It also shows that the Congo Basin still contains large mammals unknown to formal science, even while forests face growing pressure.

The result creates an immediate conservation challenge. Naming a species makes it easier to measure, protect and fund, but also reveals how little time may remain to understand it. Researchers say protecting Lomami National Park and working with surrounding communities to reduce hunting will be central to keeping Likweli from becoming a species documented only as it disappears.