I know, but why should I accept this change? Kuhn (1967), Napier (1981), Oates (1988 and 2011), Kingdon (1997), Sheila E. Curting (2002, in the book "The Guenons"), Grubb et al (2003), Gonedelé, Koffi, Bitty, Kassé, N’Guessan, Akpatou and Koné (2013), E Debra (2013) (and me (to the present)) considered both taxa to be subspecies of the same species, as well as WAZA (to the present) (while indicating that the taxonomy of this species is still unresolved), iNaturalist (to the present) and many other websites. IUCN in 2008 (after the Groves's spilt) still considered both as the same species. Altough Schreber in his original descritpion regarded roloway as a different species from the beginning, most authors always considered both as the same species, as it's logic to do just by looking at both and comparing with the other species of Cercopithecus. Just a slight difference in the shape and colour of the beard and eyebrow and other slight colour differences are not more remarkable than a difference of shape and colour between your beard (assuming that you have one...?) and my beard (when I'm not shaved...). The fact that these differences correspond precisely to different populations only means that they are different, but not necessarily different species.