A monkey with a distinctive mask-like face, found in a remote part of the Democratic Republic of the Congo, has been declared a new species – only the fifth new species of monkey documented from Africa in the past 75 years.
The monkey is known as likweli to local people who hunt it for bushmeat, and it has been given the scientific name Colobus congoensis. It lives in one of the most inaccessible parts of Africa, without paved roads or infrastructure.
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“A typical expedition involves multiple modes of transportation: a flight, followed by a motorcycle ride, two days of hiking on foot and finally travel by dugout canoe to reach the monkey’s range,” says Kate Detwiler at Florida Atlantic University.
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One of the most intriguing features of likweli is its facial appearance, says Detwiler. The light-coloured skin around the mouth and beneath the nose is unlike that of any other African colobus species, but resembles the facial pattern seen in some Asian colobine monkeys.
Detwiler and her colleagues believe the species’ mask-like face may represent ancestral traits that were present before the African and Asian colobine lineages diverged over 8 million years ago. “If so, likweli may have retained characteristics that were subsequently modified or lost in the other African colobus species,” says Detwiler.
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Like other colobus monkeys, likweli also has a distinctive body odour that defies description, she says.
Scientists first became aware of the species in 2008 when a team surveying on the banks of the Lomami river, in what is now Lomami National Park, took a photo that showed only a part of a monkey that had not been seen before, high in the canopy.
Then, in November 2018, another group again spotted the monkey, which is about 1.3 metres long and weighs around 7 kilograms. Between 2018 and 2022, there were 114 recorded observations of the new species, 25 of which were from vocalisations.
In 2021, several monkeys that had been killed by hunters for bushmeat were confiscated and handed over to researchers. Detailed morphological and genetic analysis confirmed they were indeed a wholly separate species. Genetic tests and recordings of their vocalisations also added to the evidence of their uniqueness.
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“The genetic analyses revealed that likweli is a deeply divergent lineage that split from its closest known relative, Colobus satanas, approximately 4 to 5 million years ago,” says Detwiler. “That was much older than we expected and provided strong evidence that likweli represents a distinct species.”
Likweli is isolated from C. satanas by more than 1200 kilometres and several major river barriers. Unlike most other members of the genus, which have habitats exceeding 60,000 square kilometres, likweli is only known to exist in 1700 square kilometres of rainforest.
“Hunting is one of the primary threats facing likweli, particularly because the species has such a small known range and appears to occur at low densities,” says Detwiler.
Because of the risk of poaching and the monkey’s small population and home range, the team is proposing that the species should be listed as endangered. “Now that likweli has been recognised as a distinct species, another important step would be to grant it protected status under national law,” says Detwiler. “This would make it illegal to hunt the species, including in the buffer zone surrounding the park.”
Journal Reference:PLOS One: DOI: 10.1371/journal.pone.0349857