Taxonomy and phylogeny of the South African Plocamium species Rhodophyta, Plocamiaceae

A number of taxonomic accounts have been produced for species of the red alga Plocamium in South Africa and the rest of the world; yet, the use of phylogenetic analyses to understand relationships within the genus has only been incorporated in the last decade in Japan and Europe. We used morphological and DNA sequence characters (ITSJ-5.8S-ITS2) in both independent and combined Bayesian and parsimony analyses to investigate the relationships within South African Plocamium species and between South African Plocamium species and those from elsewhere. South African Plocamium forms a monophyletic group within the genus, and Plocamium is paraphyletic with respect to Plocamiocolax, the other genus in the family Plocamiaceae. The morphological and molecular phylogenies are incongruent; morphologically relationships resolve poorly toward the tips and several of the sister relationships resolved on the basis of the nuclear ITS marker are questionable. The results of this study revealed that phylogenetic relationships within Plocamium in South Africa are highly complex and particularly when evaluated in the context of the genus worldwide. The worldwide taxonomy of the genus is in need of full revision as this and several recent studies have highlighted incongruencies in the previous morphological taxonomic accounts of the genus