Campylospermum zanaganum (Ochnaceae), a new species from the Massif du Chaillu, Republic of the Congo

Summary Campylospermum zanaganum Cranham & I.M.Turner (Ochnaceae), from mid-elevation evergreen forest near Zanaga, in the Lékoumou Department of the Republic of the Congo, is described and illustrated. Specimens of this species were previously identified as C. descoingsii Farron, with which it shares some morphological similarities, most notably the slender leaves with impressed lateral venation resulting in a distinctly bullate adaxial surface, but it differs from C. descoingsii in embryology, stature, leaf size and inflorescence form. Notes on the ecology and extinction risk of C. zanaganum are provided: it is considered to be Endangered under IUCN criterion B1 and B2 because of its extremely limited range. Although there are limited current threats, the proposed iron ore mining project in the area could pose a plausible and more severe threat in the future.