A new species of Cassipourea is described from the banks of the Mana River, in the southeastern boundary of the Korup National Park in Cameroon and placed provisionally within the subgenus Cassipourea. The leaves of the new species are close to those of C. afzelii, but its flowers differ from those of the latter and the rest of the species of the subgenus Cassipourea in having a glabrous ovary and a diplostemonous androceum, with filaments distinctly of two lengths. The illustration of the new species is provided and based on its narrow distribution, the provisional conservation status Vulnerable VU D1 is assigned.