What nocturnal primate from Southeast Asia is the only venomous primate?

The nocturnal Southeast Asian primate known as the only venomous primate is the slow loris. Slow lorises are members of the genus Nycticebus, and their toxic bite is an exceptionally rare defense among mammals.

A slow loris produces the main secretion in a gland on its upper arm, called the brachial gland. It licks this secretion and mixes it with saliva, creating a venomous compound that can be delivered through a bite. The toxin may help deter predators, parasites, and rival lorises. In humans, bites can cause severe pain and, in rare cases, dangerous allergic reactions including anaphylaxis.

Slow lorises range from parts of India and Bangladesh across mainland Southeast Asia and into Indonesia and the Philippines. They move slowly and quietly at night, gripping branches with specialized hands and feet. The name is a broad group label rather than one single species; several species are recognized, including the Bengal, Sunda, Javan, and pygmy slow lorises. They are often mistaken for harmless pets, but illegal wildlife trade and habitat loss threaten them.