New Congo Monkey Species Could Already Be Endangered, Study Shows

Deep in one of the most remote stretches of rainforest on Earth, scientists have confirmed the existence of a monkey that almost no one knew about, not even the people living closest to it. Meet Likweli, a newly named species of black colobus monkey found in Lomami National Park in the Democratic Republic of Congo. Only residents of eight of the 52 surveyed villages bordering its territory could accurately describe the animal, and it slipped past scientific notice for years even as researchers were active in the same region. Having finally pinned it down, the team is now racing to protect it.

Formally known as Colobus congoensis and described in the journal PLOS ONE, Likweli is only the fifth new African monkey species identified in the past 75 years, a rarity that shows how uncommon such discoveries have become. Its closest known relative lives more than 1,200 miles away, in western central Africa and on an island in the Gulf of Guinea. Those two family lines are so far apart that scientists estimate they split around 4 to 5 million years ago, around the time the earliest human ancestors began walking upright. That ancient divergence, along with Likweli’s distinct appearance and calls, marks a real addition to what science knows about African wildlife.

Perhaps the most surprising part of the story is how close Likweli came to going undiscovered. A photograph of the animal dates to 2008, but it was not recognized as something new until a park guard named Jean Pierre Kapale photographed it again in November 2018 and realized that the black monkey with pale markings around its mouth matched nothing known to science. An earlier patrol team had actually spotted and photographed the species in August 2018, but logged it as a known monkey, and that sighting was never flagged.

A Face Unlike Any Other Colobus Monkey

Likweli is a small, mostly black monkey with an unusual look. Its most recognizable feature is a patch of bare, pinkish-to-orange-cream skin around the mouth that extends up toward the nose. Both males and females share this facial pattern, along with a white patch of skin just below the tail. Communities in the Mituku area had their own name for it, kasaba nkoni, meaning “the branch shaker.” The Balanga people living near the western edge of its range called it Likweli, the name scientists adopted as its official common name.

Size sets it apart too. Likweli is smaller than every other known colobus monkey, with shorter fur, a smaller skull, and a distinct tooth shape. Those dental differences carry real meaning. Its closest relative eats a large share of seeds and has teeth built to crack them open, while Likweli’s teeth resemble those of leaf-eating monkeys, suggesting it depends far less on seeds and fills a different role in the forest.

How Scientists Confirmed a New Monkey Species in the Congo

Confirmation took years of patient fieldwork. Between 2018 and 2022, field teams recorded 114 encounters with the species across an estimated range of just 1,700 square kilometers, an area about two-thirds the size of Rhode Island. Teams relied on foot patrols, river patrols, dawn listening stations, and survey lines covering thousands of kilometers. Dawn listening sessions ran at 351 locations, yet Likweli’s calls turned up at only 10 of them, one measure of how scarce it is.

Three physical specimens, two adult females and one adult male, came from animals confiscated from hunters by park authorities. Researchers measured and photographed them and compared them against museum skeletons from 13 related monkey species held in collections across several countries. DNA from three Likweli individuals was analyzed alongside genetic data from dozens of other African and Asian colobine monkeys. That work placed Likweli on its own branch of the family tree, sitting closest to its distant western cousin.

Researchers also recorded and studied Likweli’s roaring calls, comparing them with six other colobus species. The calls share features with its western relative, including a rapid pulse rate and clear shifts in pitch, but differ in how the animal strings its sounds together. Six roaring events were captured in 2020 and 2021, three of them clear enough for detailed analysis.

Interviews across 52 villages revealed near-total unfamiliarity with the animal. One hunter who had once killed a Likweli could not name it locally, and another noted its strong odor. Several residents said its dawn calls sounded like a different colobus monkey already known in the area, which may be why it stayed hidden for so long.

A New Species Found Just in Time

Likweli’s situation is urgent. Researchers are proposing, as a preliminary recommendation rather than an official listing, that the species be classified as Endangered. Most of its known habitat sits inside the protected boundaries of Lomami National Park, which offers some cushion, though not enough. Park data cited by the authors document at least 15 new villages within or adjacent to the species’ range in the park’s buffer zone between 2015 and 2023 alone.

Human pressure keeps building. Congo has one of the fastest-growing populations on the continent, and forest loss in the province that holds much of Likweli’s range runs at about 4% per year. The monkey is picky about where it lives, favoring tall, dense forests on deep clay soils, and that fussiness leaves it exposed when its habitat shifts. Because it was barely known even to local hunters, it carries no established cultural protections, and newly arrived communities may not know or care about how rare it is.

Researchers are direct about the fix: protecting Lomami National Park and working with local communities to keep Likweli off the hunting menu. The park has now yielded three previously unknown or extremely rare monkey species, placing it among the most important and least explored primate refuges anywhere. Whether that awareness has come early enough to save Likweli is the open question.