Hemigrammocharax rubensteini is described from the northwestern Congo River basin in the Lékoli River of the Likouala River system, Republic of the Congo. The species differs from congeners in the combination of pigmentation pattern, meristics, and position of the dorsal fin. The presence of a well-developed pseudotympanum, a feature not previously reported in the Distichodontidae, is reported for H. rubensteini and other members of Hemigrammocharax and Nannocharax.