Description:
<jats:p> <jats:italic>Mitriostigma monocaule</jats:italic> Sonké & Dessein sp. nov., a new Rubiaceae species from south Cameroon is described and illustrated. The novelty is easily separated from the other four <jats:italic>Mitriostigma</jats:italic> species by its monocaulous growth form, the other species being shrubs, sub‐shrubs, or occasionally trees. Another typical character for the species is its supra‐axillary inflorescences paired at the nodes. The novelty is related to <jats:italic>M. barteri</jats:italic>, from which it further differs in the somewhat larger leaves with a more pronounced acumen and a higher number of secondary veins. A first conservation status for the species is given. A synopsis of the genus <jats:italic>Mitriostigma</jats:italic> with a taxonomic key is also provided.</jats:p>