DNA barcoding of South African geniculate coralline red algae (Corallinales, Rhodophyta)

Abstract COI (cytochrome c oxidase subunit 1) barcoding has been increasingly applied to geniculate coralline red algae, and has led to many taxonomic revisions, but mainly in samples from the northern hemisphere. In the present study, COI barcoding was conducted on new collections of 63 samples of geniculate corallines from South Africa to test the currently accepted morphological classification, including species of Amphiroa , Arthrocardia , Cheilosporum , Corallina , Haliptilon and Jania . The morphological classification matched the genetic data for most genera and species. However, there were significant differences within the genus Arthrocardia . Seven probable species of this genus were suggested, including two unidentified species, showing a clear need for taxonomic revision. Four Amphiroa species each formed a clade, but South African samples of A. beauvoisii were considered to be distinct from a sample from North Carolina based on sequence differences. Seven samples of Corallina positioned near C. caespitosa but not C. officinalis. Although the latter name is commonly attributed to South African Corallina , this provides evidence that C. officinalis is absent from South Africa. A combination of morphological identification and COI barcoding has been shown to be a useful tool in the delineation of species in this ecologically important group of seaweeds.