OBSERVATIONS ON THE CRUSTOSE CORALLINE RED ALGA SPONGITES-YENDOI (FOSLIE) COMB-NOV IN SOUTH-AFRICA AND ITS RELATIONSHIP TO S-DECIPIENS (FOSLIE) COMB-NOV AND LITHOPHYLLUM-NATALENSE FOSLIE

South African plants of the crustose coralline red alga Spongites yendoi (Foslie) Y. Chamberlain comb. nov. are described. This species is abundant inter-tidally on rocky shores, especially in Cape Province, and is particularly associated with communities of the pear limpet (Patella cochlear Born) in the lower eulittoral zone. South African plants are compared with the type specimens of Lithothamnion decipiens Foslie, Goniolithon yendoi Foslie and Lithophyllum natalense Foslie. All three species have relatively thin thalli, mainly composed of filaments of small, squarish cells, with a lowermost layer 1-8 filaments thick which has more or less elongate cells; cell fusions are frequent. Old tetrasporangial conceptacles do not become buried in the thallus; the conceptacles are uniporate, elliptical in vertical section, with roofs up to 6 cells thick and a pore canal lined with papillate cells. All three entities pertain to the mastophoroid genus Spongites Kutzing, but Lithothamnion decipiens has a dimerous thallus with unistratose basal filaments throughout, whereas Goniolithon yendoi and Lithophyllum natalense have a monomerous thallus with a medulla 1-8 filaments thick. It is concluded that two species are present: Spongites decipiens (Foslie) Y. Chamberlain comb. nov. and Spongites yendoi (Foslie) Y. Chamberlain comb. nov. Lithophyllum natalense is subsumed in Spongites yendoi. Spore germination characteristics of S. yendoi are discussed.