Fissipedicella orientalis gen. et sp. nov. (Ralfsiales, Phaeophyceae), a new crustose brown alga from Korea based on molecular and morphological analyses

The crustose brown algal family Ralfsiaceae comprises four genera: Analipus, Endoplura, Heteroralfsia, and Ralfsia. This study provides a detailed description of Fissipedicella orientalis gen. et sp. nov. based on molecular and morphological analyses. Our phylogenetic analyses from rbcL and concatenated dataset (rbcL + 5′ region of cytochrome c oxidase subunit I [COI-5P]) reveal that specimens collected in Korea are nested in a distinct new clade within Ralfsiaceae with robust bootstrap support and Bayesian posterior probabilities. The sequence divergences for rbcL and COI-5P between F. orientalis and other genera within Ralfsiaceae are 7.4–10.1 and 17.5–21.2%, respectively. Fissipedicella orientalis is characterized by crustose thalli with a hypothallial basal layer and erect perithallial filaments, tufts of hairs in pits, a single chloroplast per cell, plurangia with 1–3 sterile cells, and unangia on stalks composed of 1–6 vertically or obliquely cleaved cells. We propose that F. orientalis can be recognized as a new genus-level taxon within Ralfsiaceae, even though a single species represents it. Our new genus, Fissipedicella, is distinguished from the other members within the Ralfsiaceae by the type of thallus, the number of chloroplasts and tufts of hairs in pits, and the development of unangia.