Phylogeny of the Bryopsidaceae (Bryopsidales, Chlorophyta): cladistic analyses of morphological and molecular data

The five genera in the Bryopsidaceae, Bryopsis, Bryopsidella, Derbesia, Pedobesia and Trichosolen, as well as Ostreobium quekettii (Ostreobiaceae) and Codium fragile (Codiaceae) in the suborder Bryopsidineae (Bryopsidales), were examined to determine phylogenetic relationships. Cladistic analyses based on morphology, including reproductive and ultrastructural characters, using Caulerpa (Caulerpaceae) from the related siphonous suborder Halimedineae (Bryopsidales) as an outgroup, placed all species in Bryopsis, Bryopsidella, Pedobesia and Trichosolen in clades corresponding to their respective genera, with all such clades placed in a polytomy with the Derbesia species and Codium and Ostreobium. Analyses conducted using DNA sequences derived from the large subunit of ribulose- 1,5-bisphosphate carboxylase/oxygenase (rbcL) gene consistently placed Codium with the Bryopsidaceae, with Ostreobium as a more distantly related taxon. In analyses using only the first and second codon positions, Codium was placed as a sister taxon to Bryopsis within the Bryopsidaceae. In all rbcL analyses, the genus Bryopsis, with two species sampled, was monophyletic, as were generally Bryopsidella and Pedobesia. Relationships more generally between genera within the Bryopsidaceae, and with Codium, were not well supported.