This species has been split from the Tufted Capuchin (S. apella) but a recent proposal calls for a split again from the Black-striped Capuchin (S.libidinosus) into a separate specis, Azaras's capuchin (S. cay).
References:
Lynch Alfaro, J.W.; et al. (2011). "Explosive Pleistocene range expansion leads to widespread Amazonian sympatry between robust and gracile capuchin monkeys." Journal of Biogeography 39: 272–288. [PDF]
Rylands, A.B., Boubli, J.-P., Mittermeier, R.A., Wallace, R.B. & Ceballos-Mago, N. 2015. Sapajus apella. The IUCN Red List of Threatened Species 2015: e.T39949A70610943. http://dx.doi.org/10.2305/IUCN.UK.2015-1.RLTS.T39949A70610943.en . Downloaded on 05 October 2015.
Panasonic DMC-LX5 / Nikon FS 3 / 30XWA / hand-held, no adapter.