A rosette by any other name: species diversity in the Bangiales (Rhodophyta) along the South African coast

The Bangiales is an order of Rhodophyta, widely distributed around the globe and best known for its economic value in the nori industry. The morphological simplicity of the group offers limited distinguishing characters for species identification. We therefore delimited species of the Bangiales along the South African coast based on two unlinked loci, the mitochondrial cox1 gene and the plastid rbcL gene, supplemented with additional sequence data from a third gene, the nuclear nSSU. Application of DNA-based species delimitation methods including the Automatic Barcode Gap Discovery (ABGD), General Mixed Yule Coalescent (GYMC) and Poisson Tree Processes (PTP), resulted in the recognition of 10 Porphyra and three Pyropia species in South Africa, only three of which had been previously described. Additional species of Bangiales previously recorded along the South African coast were added to our final species list despite not being found in the present study, resulting in an estimate of 14–16 Bangiales species occurring along this shoreline. Most of this extensive genetic diversity has been misidentified as the commonly rosette-forming species P. capensis. The name P. capensis currently refers to a species complex and cannot be attached to any one species with certainty. All species in this complex, confirmed using genetic data, are endemic to South Africa. Our results compare well with other Southern Hemisphere countries, such as Chile and New Zealand, where high genetic diversity, species richness and endemicity have also been found.