Scientists name Colobus congoensis, Africa's fifth monkey new species in 75 years

A black colobus monkey from remote parts of the Congo Basin rainforest, known locally as likweli, has been declared a new species: Colobus congoensis. It is only the fifth new monkey species documented from Africa in the past 75 years, and the discovery comes with a built-in pressure valve for regulators and conservation decision-makers: poaching risk is already high, and the known living area appears extremely small.

The “why now” is straightforward. The team behind the identification says likweli is threatened by hunting for bushmeat, and because the species is known only from a limited rainforest area and appears at low densities, they are proposing it be listed as endangered. In other words, this is not a distant, hypothetical conservation scenario. It is a newly named species facing legal and enforcement questions immediately, including whether national law can make hunting illegal even in areas surrounding protected land.

For anyone who has not spent time thinking about how new species get recognized, this case shows the mix of field reality and lab confirmation that has to line up. Scientists first became aware of likweli in 2008 when a surveying team on the banks of the Lomami river, in what is now Lomami National Park, took a photo that showed only part of a monkey not seen before, high in the canopy. Then in November 2018, another group spotted it again. Researchers report that between 2018 and 2022, there were 114 recorded observations of the new species, including 25 from vocalisations. In 2021, several monkeys killed by hunters were confiscated and handed over to researchers. Those specimens became crucial inputs for morphological and genetic analysis.

The distinctive biology is part of what made the team pay attention in the first place. Detwiler and colleagues point to a mask-like facial appearance: light-coloured skin around the mouth and beneath the nose that is unlike that of any other African colobus species, yet resembles facial patterning seen in some Asian colobine monkeys. The scientists interpret this as potentially related to ancestral traits that existed before African and Asian colobine lineages diverged over 8 million years ago. Their idea is evolutionary, not marketing. If likweli did retain older characteristics, other African colobus species may have subsequently modified or lost similar traits.

But the real “lock it in” comes from the genetic and geographic evidence. 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. That split is not just old; it is also geographically isolating. Likweli is separated from C. satanas by more than 1200 kilometres and several major river barriers. Meanwhile, where most members of the genus have habitats exceeding 60,000 square kilometres, likweli is only known to exist in 1700 square kilometres of rainforest.

That combination, small range plus low densities plus active hunting, is the conservation equivalent of a cash-flow squeeze. The paper’s framing is blunt: hunting is one of the primary threats, particularly because the species has such a small known range and appears to occur at low densities. Scientists also note a behavioral and sensory detail that underscores how hard this animal is to miss once you are tuned in: like other colobus monkeys, it has a distinctive body odour that “defies description.” For the field teams, that kind of signature can help, but it does not remove the larger constraint. If you have a confined population, even modest levels of poaching can disproportionately affect survival.

From a regulatory standpoint, the next step the team proposes is clear. Now that likweli has been recognized as a distinct species, they say an important move would be to grant it protected status under national law. The goal is to make it illegal to hunt the species, including in the buffer zone surrounding the park. That detail matters because “protected area” rules often fail at the edges. Buffer zones are where enforcement can be weakest, where livelihoods and hunting pressure collide with conservation boundaries.

This is also a reminder of how discovery can accelerate urgency. Only five new African monkey species have been documented in the past 75 years, so each classification carries weight in how conservation organizations prioritize funding and how authorities update legal frameworks. Even though this is biology, the executive-level lesson is about timing: recognition triggers policy windows. When a species is newly defined and already facing poaching pressure, the gap between scientific confirmation and protective law can determine whether “endangered” is a label or a late diagnosis.

Journal Reference: PLOS One: DOI: 10.1371/journal.pone.