Order Artiodactyla Author Wilson, Don E. Author Reeder, DeeAnn text 2005 The Johns Hopkins University Press Baltimore Mammal Species of the World: a Taxonomic and Geographic Reference (3 rd Edition), Volume 1 637 722 book chapter 0-8018-8221-4 10.5281/zenodo.7316519 Cephalophus callipygus Peters 1876 Cephalophus callipygus Peters 1876 , Monatsb. K. Preuss. Akad. Wiss. Berlin , 1876: 483 . Type Locality: "Africa occidentalis ( Gabun )" ( Gabon , Gabon River). Vernacular Names: Peters' Duiker . Distribution: West of Congo and Ubangi Rivers in S Cameroon , S Central African Republic , Republic of Congo , and Gabon . Conservation: IUCN – Lower Risk (nt). Discussion: Thought possibly to be conspecific with natalensis and/or adersi ( Ansell 1972:33 ) but callipygus is not closely related to natalensis ( Groves and Grubb, 1974 ) .