Heydrichia woelkerlingii gen. et sp. nov., a newly discovered non-geniculate red alga (Corallinales, Rhodophyta) from Cape Province, South Africa

Heydrichia woelkerlingii gen. et sp. nov., a new non-geniculate coralline alga from South Africa, has some affinity with Sporoltihon. Heydrichia and Sporolithon have many vegetative characters in common, but Heydrichia differs in its reproductive characters: cruciately divided tetrasporangia subtended by one or more stalk cells, and housed in sporangial complexes which are themselves within sori; dendroid spermatangial branches restricted to the floor of the gametangial conceptacles; carpogonial branches consisting of a single carpogonium on a support cell; lack of a fusion cell and carposporangia are formed across the floor of the cystocarp. The new taxon shows tetrasporangial and post-fertilization characters not described previously in the Corallinales. In order to accommodate both Heydrichia and Sporolithon within the Corallinales, we propose an emendation of the order to include all genera of red algae with calcite walls and sporangial sori. Heydrichia is an ecologically important member of the algal flora of Cape Province, South Africa, and is endophytized by many organisms including a marine ascomycete.