Morphology, basiphyte range, and plastid DNA phylogeny of Campylaephora borealis stat. nov. (Ceramiaceae, Rhodophyta)

The ceramiaceous red algal genus Campylaephora J. Agardh includes three species that occur exclusively in the northwest Pacific Ocean. We studied the morphology, basiphyte range, and molecular phylogeny of Campylaephora borealis, considered a variety of the C. crassa complex, using material collected over its geographic range. Samples of C. borealis, C. crassa, C. hypnaeoides, and putative relatives were taken from 43 locations in Korea, Japan, and Far-East Russia, including the type localities of the first two of these species. Campylaephora borealis is distinguished by proliferous branchlets on all sides of the main branches and an alternate branching pattern. It is characteristically epiphytic on diverse plants, such as Prionitis divaricata, and occurs mostly in exposed sites. It is distributed from Maengbang, Korea to Nakhodka, Far-East Russia. Based on pairwise divergences of the plastid RuBisCo spacer region and psbA sequences, C. borealis is more closely related to C. hypnaeoides than to C. crassa. The topology of the tree constructed using the combined data shows the monophyly of C. borealis, which is clearly separated from other Campylaephora species and putative relatives. Our molecular data together with the basiphyte range and a morphological reappraisal point to the independent taxonomic position of C. borealis, isolated from Campylaephora crassa. Therefore, we propose to raise Campylaephora crassa f. borealis to the rank of species: Campylaephora borealis (Nakamura) Seo et al., stat. nov. The phylogeny of Campylaephora is also discussed.