PNEOPHYLLUM-AMPLEXIFRONS (HARVEY) COMB-NOV A MASTOPHOROID CRUSTOSE CORALLINE RED ALGAL EPIPHYTE FROM NATAL, SOUTH-AFRICA

Pneophyllum amplexifrons (Harvey) comb. nov. is an epiphytic crustose coralline alga (Rhodophyta, Corallinaceae) of the subfamily Mastophoroideae. It occurs commonly in northern Natal, South Africa and is particularly abundant on intertidal populations of the seagrass Thalassodendron ciliatum (Forsskal) den Hartog. It agrees well with the type specimen of Melobesia amplexifrons Harvey. A germination disc with 8 central cells is present, as usually seen in Pneophyllum. The roof of the tetrasporangial conceptacle forms from filaments surrounding and filaments interspersed among sporangial initials. A pore canal lined with numerous small cells confirms that the species pertains to the mastophoroid genus Pneophyllum. Two diagnostic features of P. amplexifrons are humps of uncalcified filaments at the thallus surface and tapered pore canals in the tetrasporangial conceptacles, lined with small, upward-pointing, non-protruding filaments. Comparison with syntypes of Lithophyllum pseudolichenoides Heydrich shows this species to be conspecific and it is subsumed in Pneophyllum amplexifrons.