There are 2 species recorded from Tanzania: Colobus angolensis (the Angolan Colobus) and Colobus guereza (the black and white Colobus). Both species are recognizable by the long black and white hair flowing from the body. The complex stomach of these animals allows the consumption of plant material that other animals cannot tolerate. The lack of a thumb is a characteristic of the genus.

There is still some confusion regarding this group of primates. There are forms in Zanzibar (Piliocolobus kirkii), and also in the Udzungwa Mountains (Piliocolobus gordonorum). Some biologists refer to both forms as Procolobus pennantii.