What is "procolobus"

Procolobus is the genus of the red colobus monkeys and the olive colobus. Some authorities restrict the genus Procolobus to the olive colobus, placing the remaining in Piliocolobus. They are found in Africa and almost entirely restricted to forests (only the Zanzibar red colobus prefers more shrubby habitats). They are mainly folivorous and most of the species are threatened.