Systematics of Hypnea asiatica sp. nov. (Hypneaceae, Rhodophyta) based on morphology and nrDNA SSU, plastid rbcL, and mitochondrial cox1

Publisher Website
Google Scholar
Abstract
Hypnea is an economically and ecologically important red alga including about 53 species worldwide. Here, we describe H. asiatica sp. nov. from Korea, Japan, and Taiwan. Specimens of this species from the northwestern Pacific have often been assigned to H. charoides. Hypnea asiatica is distinguished by percurrent main axes, branches with abruptly curved adaxial branchlets, and the presence of lenticular thickening in the walls of medullary cells. It is abundant in wave‐exposed sites from summer through fall and produces tetrasporangial sori in fall. We analyzed three genes from three different genomes: nuclear SSU rDNA from 27 specimens, plastid rbcL from 51 specimens, and mitochondrial cox1 from 41 specimens, including putative relatives and H. charoides from Australia. All analyzed DNA datasets produced congruent trees in which H. asiatica was always separated from H. charoides. Network analysis of cox1 haplotypes indicated geographic structuring across the species distribution range. Although Hypnea was found to be monophyletic, the distant relationship between H. asiatica and the other species raises questions about divergence pathways within the genus.