Background and aims – The treatment of Calycobolus Willd. ex J. A. Schult. (Convolvulaceae) for tropical Africa by Lejoly & Lisowski, published in 1985, does not work satisfactorily in the identification of specimens from western Central Africa, particularly from Gabon. A revision of their work is undertaken to solve this problem. Methods – Normal practices of herbarium taxonomy have been applied to study most of the available herbarium collections, mainly from BM, BR, GOET, K, LBV, LISC, LISU, MO, P, WAG. Key results – The number of species recognised by Lejoly & Lisowski is reduced from 25 to 13. Calycobolus hallianus Breteler from western Ghana is the only new species that is added. A new key is presented in which three new characters are introduced, namely the position of the anthers, whether being erect or pendulous at anthesis, and having long weak hairs along their slits or not, and the presence or absence of leaf domatia. All species are fully treated and distribution maps are provided. Some illustrations are added.

TAXONOMY; NEW SPECIES; TROPICAL AFRICA; CONVOLVULACEAE; CALYCOBOLUS