Updated keys to the non-geniculate coralline red algae (Corallinophycidae, Rhodophyta) of South Africa

• The taxonomy of the non-geniculate coralline red algae (NGCA) is globally in flux.
• There have been new records and changes to the taxonomic status of many SA species.
• An updated key to the South African NGCA species is provided.
• Comments on the diversity of the South African NGCA are made.

The South African rocky subtidal and intertidal habitats are rich in diversity and abundance of non-geniculate coralline red algae. Despite their ubiquity, they are still a comparatively poorly known group of marine organisms. Ongoing taxonomic changes have meant that the classification and characterisation of these algae have been in constant flux. In light of these ongoing changes, the aim of this paper was to reconcile the most recent publications with previous consolidated records to produce the most up-to-date keys to the non-geniculate coralline red algae of South Africa. As a consequence of ongoing taxonomic changes and additional, more focused collections, currently 45 species of non-geniculate coralline red algae, belonging to three orders (Corallinales, Hapalidiales, Sporolithales), three families (Corallinaceae, Hapalidiaceae, Sporolithaceae), seven subfamilies (Choreonematoideae, Hydrolithoideae, Lithophyloideae, Mastophoroideae, Melobesioideae, Metagoniolithoideae, Neogoniolithoideae) and 18 genera are now recognised to occur along the South African coast. South Africa has representative species from more than half of the currently recognised extant genera of non-geniculate coralline red algae, with the order Corallinales best represented. Nearly one in four species are endemic to the South African coastline and nearly one in three species are endemic to the region. Recent molecular evidence has pointed to a large number of cryptic species, suggesting that the true diversity for South Africa is substantially greater than what is currently recognised based solely on morphology and anatomy.