The genus Ptilothamnion (Ceramiaceae, Rhodophyta) in South Africa, with the description of P. goukammae spec. nov

The genus Ptilothamnion Thur. in Le Jolis is represented in South Africa by three, or possibly four species: P. codicolum, P. polysporum, P. goukammae spec. nov., and reportedly P. subsimplex, all recorded after 1983. An earlier record of P. pluma is probably erroneous. The new species differs from known representatives of the genus by producing strictly one involucral filament from the hypogenous cell and additionally one from the subhypogenous cell. Ptilothamnion is a widespread genus, but rarely with more than two species in any given regional flora. A critical comparison of the c. 12 species shows that very few characters are shared by all of them.