The African species of Tetrorchidium have been studied in order to investigate the report of a corolla present in the female flowers of T. congolense. The study revealed that T. congolense does not have a corolla but an involucre. The same holds for T. gabonense which is described for the first time. Tetrorchidium tenuifolium is lectotypified and treated as a synonym of T. oppositifolium, which is lectotypified as well. Tetrorchidium ulugurense is maintained as a distinct species. A key to the resulting five species is given and their distribution is mapped.
Tetrorchidium, Euphorbiaceae, involucre, Gabon