In 2008, biologists working through a little-known block of forest in the central Democratic Republic of Congo came away with a single out-of-focus photograph of a black monkey that matched nothing in their field guides. Eighteen years later, the animal has a name.
Writing in PLOS One, a team led by John Hart of the Lukuru Wildlife Research Foundation in Kinshasa has described it as Colobus congoensis. Specialists count it as only the fifth monkey species formally described in Africa in the past 75 years — an unusual event in an order that includes humans and has been combed over more thoroughly than almost any other branch of the mammal family.
Its coat is glossy and almost entirely black. What sets it apart is the face: a bare patch of pink-to-orange skin rings the mouth and reaches up to the base of the nostrils, like a mask. At around seven kilograms it is smaller than other colobus monkeys, and its voice carries — a deep roar audible through much of the day, recognisable by its rapid pulse and by the grunt that punctuates each sequence. In a handful of villages people know it as likweli, and as kasaba nkoni, the twig shaker.
Local knowledge is what cracked the case. The 2008 image was shelved while the same researchers pursued another unknown primate from these forests, the lesula, described in 2012. The trail reopened in 2018, when the Congolese field researcher Jean Pierre Kapale photographed the black monkey repeatedly on survey patrols and insisted it was new to science. He was right. Over the years that followed, the team logged 114 sightings, recorded its calls, gathered DNA and examined carcasses confiscated from hunters.
The genetics held a surprise. The nearest known relative, the black colobus Colobus satanas, lives more than 1,200 kilometres away in western Central Africa, and the two lineages parted four to five million years ago — among the earliest divisions known within the colobus group, according to co-author Kate Detwiler of Florida Atlantic University.
Named, and already at risk
The monkey appears to occupy roughly 1,700 square kilometres east of the Lomami River, and to depend on closed-canopy forest growing on nutrient-rich loamy soils. Hart estimates fewer than 1,000 individuals survive. It is naturally scarce rather than hunted into scarcity, he said, though hunting continues and settlements are pushing further into the basin. The team has applied to have the species listed as endangered on the IUCN Red List. Most of the known population sits inside Lomami National Park — no guarantee of safety, cautions Terese Hart, the foundation's director.
For Detwiler, the find is a triumph and a warning at once: a reminder that some of the rarest animals on Earth may vanish before anyone knows they were there.