Two species of the coralline red algal genus Mesophyllum (Corallinaceae, Melobesioideae) are reported from the southernmost coral reefs in the western Indian Ocean at Sodwana Bay, Natal, South Africa. Specimens attributed to Mesophyllum erubescens (Foslie) Lemoine were compared with the type specimens of Lithothamnion erubescens Foslie and L. erubescens f. madagascariensis Foslie [= M. madagascariensis (Foslie) Adey]. The comparison showed that the local material and the type specimens are all conspecific, confirming previous suggestions that M. madagascariensis should be subsumed in M. erubescens. Mesophyllum funafutiense (Foslie) Verheij was also recorded. These species are distinguishable on the basis of the structure of the roof and the pore of the tetrasporangial conceptacles, and on the size of tetrasporangial conceptacles and tetrasporangia.