Presbytis percura is a leaf-eating monkey recorded in forests of Riau Province, Sumatra. A 2020 study recognized the Riau form, formerly treated as a subspecies of P. femoralis, as a separate species.
The older description of the Riau form says its crown, back, hands, feet, and tail are black. The underside is white, with a narrow white chest stripe and white inner arms, inner legs, and chin.
The study links the species to isolated forests in Riau Province. This describes forest patches in the Riau region of Sumatra, not a continuous forest range.
An extinction-risk assessment has not been added yet.