Taxonomy of Chlorocyathus (Apocynaceae: Periplocoideae)

The genus name Chlorocyathus was coined by Oliver [Oliver, D., 1887. Chlorocyathus monteiroae. Hooker, Icones plantarum 16, t. 1557 and 1591.] for a specimen collected at Maputo, Mozambique. [Brown, N.E., 1907. Raphionacme monteiroae. In: Thiselton-Dyer, W.T. (Ed.), Flora Capensis, vol. 4. Lovell Reeve and Co, London, pp. 533-534.] sunk the monotypic Chlorocyathus into Raphionacme Harv. However, new information shows that Oliver was correct in regarding Chlorocyathus as different from Raphionacme. The name Chlorocyathus is thus reinstated, and the monotypic Kappia Venter, A.P. Dold and R.L.Verh., which resembles Chlorocyathus closely, becomes a synonym of it. Chlorocyathus will therefore include two species, C. monteiroae Oliv. and C. lobulata (Venter and R.L.Verh.) Venter. Nomenclature, descriptions, distribution patterns, ecology, and a key to the two species of Chlorocyathus are provided. Chlorocyathus is, furthermore, compared with selected African genera of Periplocoideae, and a key is provided to the tuberous-rooted African periplocoid genera.