What's in a name? Monophyly of genera in the red algae: Rhodophyllis parasitica sp nov (Gigartinales, Rhodophyta); a new red algal parasite from New Zealand

Red algal parasites are common within red algae and are mostly closely related to their hosts, but have a reduced habit. In the past, red algal parasites, due to their reduced morphology, have been given distinct generic names, even though they are often phylogenetically nested in their host's genus. This is a problem nomenclaturally for maintenance of a taxonomy based on monophyly. This study investigates the morphology, genetic variation and distribution of an undescribed red algal parasite growing on its host Rhodophyllis membranacea, widely distributed throughout New Zealand. Microscopy, molecular markers (plastid, mitochondrial, nuclear), and herbarium investigation were used to investigate this species. The parasite is widely distributed throughout New Zealand. All molecular markers clearly show that the parasite is almost identical to the host, even though morphologically quite distinct from members of the host genus. We believe that to maintain monophyly of Rhodophyllis the parasite should be described as a new species of Rhodophyllis, Rhodophyllis parasitica sp. nov. We also recommend that in order to maintain generic monophyly most red algal parasite genera should also be transferred to their host genus.