Current status of freshwater red algal diversity (Rhodophyta) of the African continent including description of new taxa (Batrachospermales)

Freshwater red algae have been collected on the African continent since the early 1800s. However, the collections have been sparse and geographically restricted. The present study sought to bring together information from the literature, herbarium specimens, and newly collected specimens to provide an updated assessment of the freshwater red algal diversity of the African continent with a focus on the species-rich Batrachospermales. DNA sequence data and morphological observations were conducted for recently collected specimens. From these analyses, four new taxa are proposed: Kumanoa bouwmanii, Sheathia murpheyi, Sirodotia kennedyi, and the form taxon 'Chantransia azurea'. DNA sequence data had been previously published for Kumanoa iriomotensis, Sirodotia aff. huillensis, and S. suecica. With this study, we have added sequence data for Torularia atra as well as a second location for S. suecica. In total, there are eight taxa with sequence data, of which five appear to be endemic. From our assessment of literature reports and herbarium specimens, we conclude that Kumanoa, Sirodotia, and Torularia have often been collected and are relatively geographically widespread with two or more species present. In addition, Montagnia, Nothocladus, Paralemanea, Sheathia, and Visia as well as Batrachospermum section Gonimopropagulum are represented in the flora. We estimate that 14 to 19 batrachospermalean taxa can be recognised for the African flora, and that with more study, that number could easily double or triple based on the diversity known from other well-studied continents.