A new species of Curtonotum Macquart is described and figured from Nouabalé-Ndoki National Park, Republic of Congo, based on the unique male holotype from disturbed Guineo-Congolian rainforest. The new species clearly belongs to the Curtonotum platyphallum species-group in sharing the synapomorphy of the basiphallus with an angulate ventrally expanded and concave process. Additional key couplets are provided to distinguish the new species from its congeners.