Scientists discover a ‘remarkable’ new monkey species with orange lips and a froglike roar

A “remarkable” African monkey with a distinct orange patch around its mouth and a deep, croaky roar, found in the Democratic Republic of the Congo (DRC), is in fact a new species—and possibly already endangered.

The new species, Colobus congoensis, or Likweli, was discovered in Congo’s Lomami National Park and is closely related to its “sister” species, the black colobus. Before now, the monkey was a familiar sight to local communities, but scientists had never formally described it.

Now, in a new paper published on Wednesday in PLOS One, researchers have confirmed with genetic analyses that C. congoensis is a new species. It is just the fifth new African monkey species identified in the past 75 years.

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C. congoensis is small—adults typically weigh about 15 pounds (seven kilograms)—and is recognizable by a “striking orange cream patch” around its mouth and a thatch of fine white hair on its butt, the study authors write. To the untrained ear, its call sounds a bit like a frog or pig snorting.

This discovery was nearly two decades in the making. The hunt began in 2008, when a research crew exploring the forest captured the first known photo of the monkey.

Something was “strange” about its face, explains Junior Amboko, a co-author on new study and a Ph.D. student in the Department of Biological Sciences at Florida Atlantic University.

But the photo was blurry, and at the time, scientists couldn’t be sure it was a new species.

Later, more pictures showed the monkey didn’t have a thumb, revealing another clue to the primate’s identity—the lack of this digit is characteristic of Colobus monkeys. “But we didn't know if it was a [new] species or a subspecies,” Amboko says.

In 2020 Amboko and his colleagues launched the Likweli Project, a research effort to classify the mysterious monkey. They collected more pictures, documented its calls and analyzed samples from dead monkeys confiscated from illegal hunting activity in the park.

It was the genetic analysis of tissue samples that finally confirmed it was a new species. “We were shocked with the genetic data because it gave us such a signal of deep divergence,” says Kate Detwiler, senior author of the new study and an associate professor of biological sciences at Florida Atlantic University. Amboko suggested the name Colobus congoensis to recognize the rich biodiversity of the DRC.

C. congoensis is already under threat, in part because of hunting and human population growth. In the new paper, the researchers propose it be listed by the International Union for Conservation of Nature (IUCN), which tracks at-risk animal species, as Endangered.

“Protection of Lomami National Park, within which most of the C. congoensis range occurs, and engagement of local communities in not hunting the species are the most important actions needed to ensure the conservation of C. congoensis,” the authors write in the study.