Lesula Monkey

The Lesula Monkey (Cercopithecus lomamiensis) is a relatively recently discovered species of Old World monkey found in the central forests of the Democratic Republic of the Congo (DRC). Officially described in 2012, the Lesula is notable for its distinct facial features, unique colouring, and restricted geographic distribution within the Congo Basin. Its discovery was significant because it represented one of the few new African primate species identified in the 21st century, highlighting the biological richness and continuing scientific importance of the Congo rainforest.

Discovery and Classification

The Lesula monkey was first recognised as a new species in 2007, when researchers working in the Lomami Basin in central DRC observed an unusual monkey kept as a pet by villagers in the town of Opala. Further field studies and genetic analyses confirmed it as a distinct species of guenon, closely related to the Owl-faced monkey (Cercopithecus hamlyni).
After years of research, including morphological and DNA comparisons, the species was formally named Cercopithecus lomamiensis in 2012 by biologists John and Terese Hart and their team from the Lukuru Wildlife Research Foundation and Yale University’s Peabody Museum of Natural History. The species name lomamiensis is derived from the Lomami River, which runs through the heart of its natural habitat.

Physical Characteristics

The Lesula monkey exhibits distinct physical traits that differentiate it from other members of the genus Cercopithecus:

• Facial Appearance: The most striking feature is its pale, hairless face with a light blue-grey tone and a pinkish nose and lips, giving it an almost human-like expression.
• Body Colouration: It has a golden-brown crown and back, with greyish limbs and a creamy-yellow chest and collar.
• Size: Adult males are larger than females, averaging about 45–65 cm in body length, with an additional long tail that aids in balance.
• Distinctive Features: Males possess a bright blue perineum, a trait common among guenons, used for social and sexual signalling.

Overall, the Lesula combines characteristics of forest-adapted monkeys with distinctive markings that make it easily recognisable among African primates.

Habitat and Distribution

The Lesula is endemic to the Lomami and Tshuapa river basins in the central Democratic Republic of the Congo, specifically within the TL2 region — the area bounded by the Tshuapa, Lomami, and Lualaba Rivers. This remote and largely uninhabited forest region is characterised by dense lowland rainforests, swamp forests, and riparian woodlands.
The rivers act as natural barriers, isolating the Lesula from closely related species and limiting its range. Such geographic isolation likely contributed to its distinct evolution.

Behaviour and Ecology

Although the Lesula remains one of the least-studied primates, available field observations provide insight into its behaviour and ecology:

• Diet: It is primarily frugivorous, feeding on fruits, seeds, leaves, and occasionally invertebrates.
• Activity: Like other guenons, it is diurnal (active during the day) and arboreal (living mainly in trees), though it may descend to the ground to forage.
• Social Structure: Lesula monkeys live in small family groups consisting of one adult male, several females, and their young. Their communication involves vocal calls, body postures, and facial expressions typical of guenons.
• Reproduction: Limited data exist, but reproductive patterns are likely similar to those of related species, involving year-round breeding with a gestation period of around 5–6 months.

Conservation Status

According to the International Union for Conservation of Nature (IUCN), the Lesula monkey is classified as Vulnerable. Its restricted range and growing human pressures make it particularly susceptible to population decline.
Major threats include:

• Bushmeat Hunting: The species is frequently hunted for food in local communities, a widespread threat to many forest mammals in central Africa.
• Habitat Loss: Logging, mining, and agricultural expansion are degrading the Lesula’s rainforest habitat.
• Isolation: Its limited geographic range makes recovery difficult if populations decline.

Efforts to protect the species are underway through the creation of the Lomami National Park (established in 2016), which includes significant parts of the Lesula’s habitat and aims to protect the biodiversity of the TL2 region.

Scientific and Ecological Importance

The discovery of the Lesula has great scientific significance:

• It underscores that large, previously unknown mammal species still exist in relatively unexplored parts of Africa.
• It provides valuable insights into African primate evolution, particularly speciation driven by riverine barriers.
• Its genetic and behavioural traits help researchers better understand the diversity and adaptive strategies of guenon monkeys in tropical ecosystems.

From an ecological perspective, the Lesula plays an important role in seed dispersal, contributing to the regeneration and stability of rainforest ecosystems.

Cultural and Local Perspectives

In local communities of central Congo, the Lesula is known by names such as lesula or “lokoso”, and has been familiar to indigenous people for generations, though unknown to the scientific community until recently. Local traditions regard the monkey as shy and elusive, and it is occasionally depicted in folklore.