Orange-Lipped Monkey Mystifies Scientists for 20 Years

In 2008, researchers in the Congo Basin captured a blurry image of a unique monkey. While it shared characteristics with the Colobus genus, its diminutive size, shiny black fur, striking facial features, and distinctive white markings on its rear differentiated it from any previously identified species. Subsequently, it vanished from sight.

After this initial observation, scientists shifted their focus to other species due to the lack of further sightings. in 2018, researchers near the original sighting location encountered the monkey once more, this time capturing much clearer photographs.

“We recognized it was something extraordinary,” stated Junior Amboko, a field conservationist from the Democratic Republic of the Congo and a PhD candidate at Florida Atlantic University, in an interview with Gizmodo. At that time, he was supervising field researchers in Lomami National Park, situated deep within the Congo Basin.

The new images indicated that the monkey lacked thumbs, confirming its classification within the Colobus genus. its unusual characteristics, particularly the pinkish-orange area surrounding its mouth and nose, led Amboko to conclude that it represented an unidentified species or subspecies. In 2020, he initiated the first formal study of this enigmatic monkey. The results, published recently in the Public Library of Science (PLOS) One, affirmed that it is indeed a newly discovered species of Colobus, now officially recognized as Colobus congoensis.

Unlocking the Mystery of the Colobus Congoensis

The breakthrough occurred in 2021 when Amboko and his team acquired specimens of C. congoensis that had been confiscated from hunters within the National Park. Before this, the researchers depended on fecal samples for genetic analysis, but tissue samples provide significantly more detailed information.

This fortunate discovery enabled them to extract DNA from the new species and compare it with all known Colobus genomes. “When we analyzed the genetics and shared our findings, we were astonished by the deep divergence we observed,” remarked senior author Kate Detwiler, an associate professor of anthropology at Florida Atlantic University, in her conversation with Gizmodo.

Through comparisons of mitochondrial DNA and fossil records, the researchers estimate that C. congoensis diverged from its closest known relative, C. satanas (the black colobus), between 4.3 million and 5.8 million years ago. This marks one of the oldest known evolutionary splits within the Colobus lineage. Presently, these two closely related species inhabit distinctly different regions, separated by about 750 miles (1,200 kilometers).

Further examinations of C. congoensis in terms of anatomy, behavior, and vocalizations provided additional evidence supporting its status as a distinct species, unraveling a mystery that had perplexed researchers for nearly two decades. numerous questions about these elusive monkeys remain unanswered.

Identifying Conservation Challenges for Colobus Congoensis

To gain insights into the distribution and behavior of C. congoensis, the researchers engaged with local communities across 52 villages bordering Lomami National Park. To their surprise, only eight of these villages recognized the species.

Even among those familiar with C. congoensis, descriptions were vague, according to Amboko. One community referred to the species as “Likweli,” while another named it “kasaba nkoni,” translating to “the branch shaker.” Locals generally noted that the species is quiet and elusive, with a restricted distribution. Between 2018 and 2022, researchers recorded 114 sightings over an estimated range of just 660 square miles (1,700 square km)—an unusually limited territory for Colobus monkeys.

Given its elusive nature, Amboko and his colleagues suspect that C. congoensis has a small range and population size, though further research is necessary to confirm this. Nonetheless, increasing hunting pressure and ongoing habitat destruction may threaten what appears to be a relatively vulnerable species. The researchers recommend classifying C. congoensis as endangered on the International Union for Conservation of Nature (IUCN) Red List.

Determining the species’ range, population size, and conservation status will enhance understanding of C. congoensis. Amboko, Detwiler, and their colleagues also have additional inquiries. Amboko intends to explore which parts of the canopy these monkeys primarily inhabit, while Detwiler is particularly interested in their reproductive biology.

The team has secured funding for further fieldwork, suggesting they could find answers to these questions soon. For the moment, they celebrate the addition of another primate species to the scientific community. This discovery underscores the remarkable biodiversity of the Congo Basin, and Amboko hopes it will encourage more researchers to explore this natural laboratory.