Anew species of Aglaothamnion (Ceramiales, Rhodophyta) from Korea, Aglaothamnion inkyui sp. nov

The genus Aglaothamnion has been separated from Callithamnion based on several characters, most notably the presence of a single nucleus per cell in Aglaothamnion versus multi-nucleate Callithamnion. Few studies have investigated whether these genera are genetically monophyletic. Several species of Aglaothamnion have been reported from Korea, but no phylogenetic studies have been conducted on them. We collected a specimen resembling the genus Aglaothamnion from the east coast of Korea, which is characterized by alternate branching, long axial cells and uninucleate cells. Phylogenetic analyses using rbcL sequences and two DNA-based species delimitation analyses revealed that this specimen is a new species closely related to A. pseudobyssoides. Morphologically, the new species was distinguished by longer axial cells and shorter determinate branches compared to A. pseudobyssoides. The new specimen did not show any reproductive features. Our new species and A. pseudobyssoides are distantly related to other sequences used in the analysis. Our phylogenetic analyses, using our samples and sequences deposited in Genbank, suggests that the named genera, Callithamnion and Aglaothamnion, are not monophyletic, or that the samples were incorrectly named before being submitted to Genbank. While the taxonomy of these two genera requires further analysis, with more markers and type specimens sequenced, it is clear that our new sample is a distinct genetic species. Therefore, we propose the establishment of a new species of Aglaothamnion from Korea, Aglaothamnion inkyui sp. nov.