Designation of a New Subspecies of Angola Colobus Colobus angolensis Sclater, 1860 (Primates: Cercopithecidae) Endemic to the Mahale Mountains of Western Tanzania
By Yvonne A. de Jong and Thomas M. Butynski. Primate Conservation 37.

Read about it here: https://www.wildsolutions.nl/mahale-angola-colobus/