XVI International Botanical Congess

The red algae, Division Rhodophycota, class Rhodophyceae, presently consists of two subclasses, a paraphyletic Bangiophycidae and a monophyletic Florideophycidae. Phylogenetic trees obtained from nucleotide sequences of nuclear 18S rRNA, plastid rbcL and mitochondrial genes support new classifications based on morphological, cytological and biochemical evidence. Molecular data have been used to: test hypotheses about pit-plug ultra-structure and evolution, and their significance for classification, to demonstrate from cell wall chemistry that agar-type, carrageenan-type and intermediate-type phycocolloids correlate with recent molecular phylogenies, to support hypotheses about biogeographic distribution patterns shaped by vicariant and dispersal events and species ecophysiology, and to establish that red algal parasites have evolved monophyletically and polyphyletically from their red algal hosts.