Philosophiae Doctor - PhD / The aim of this study was to document the intertidal and shallow subtidal species of non-geniculate coralline red algae from the South Africa south coast. The main emphasis of the study are encompassed in four research chapters and one concluding chapter focusing on: 1) the documentation of the non-geniculate coralline red algae occurring along the South Africa south coast; 2) revisiting the Leptophytum-Phymatolithon complex in order to resolve the taxonomic status of species previously ascribed to the genus Leptophytum from South African; 3) starting to prepare modern monographic accounts of the higher taxa; and 4) the production of updated keys to all the currently recognised taxa of non-geniculate coralline algae for South Africa. Although nowhere near complete, here we present our findings and report on the current biodiversity status of the non-geniculate coralline red algae after a further four years of extensive sampling.