A molecular phylogeny of the Gelidiales (Rhodophyta) based on analysis of plastid rbcL nucleotide sequences

Parsimony analyses of rbcL nucleotide sequences were used to develop hypotheses of relationships among taxa in the taxonomically difficult order Gelidiales including species from seven currently recognized genera: Capreolia, Gelidiella, Gelidium, Onikusa, Pterocladia, Ptilophora, and Suhria. Nucleotide sequences of rbcL from red algae are variable and provide a large number of informative characters for phylogenetic analysis, yet the absence of insertion/deletion allows for the unambiguous alignment of sequences. Species were resolved into 10 well-supported major clades representing genera and species complexes. The topological positions of these 10 clades within trees are also well supported and indicate that Gelidium and Pterocladia as currently circumscribed are not monophyletic. These results call for a revision of the classification of the Gelidiales.