A multigene phylogeny of the Gelidiales including nuclear large-subunit rRNA sequence data

Partial sequences (1032 bp) of the nuclear-encoded large ribosomal RNA gene (LSU) were determined for 16 gelidialean species, and analyzed separately and in combination with plastid rbcL and nuclear SSU gene sequences. The nu mber of informative characters and levels of sequence divergence among taxa are intermediate in LSU sequences as compared to that for rbcL and SSU. An alyses of the separate LSU, and a combined LSU, SSU, and rbcL data sets hav e identified early-diverging lineages within the Gelidiales including Gelid iella, Pterocladia, Pterocladiella, and a lineage including Gelidium and sp ecies classified in other genera. The relationships among most gelidialean taxa are well-resolved and well-supported by analyses of the combined data; however, the relationships of Ptilophora and Capreolia remain unclear. It is speculated that these two lineages have diverged from a common ancestor over an evolutionarily short period of time.