Boreolithothamnion astragaloi, a coralline algal species belonging to the family Hapalidiaceae and order Hapalidiales, has been reported from British Columbia, Canada in northeastern Pacific. In this study, we report B. astragaloi for the first time from Korea, representing its initial record in the northwestern Pacific. Morpho-anatomical and molecular analyses of Lithothamnion-like specimens collected in Korea revealed that some individuals correspond to B. astragaloi. This species is characterized by flattened, flared epithallial cells; subepithallial initials as long as or longer than the cells immediately subtending them; cell fusions; multiporate tetrasporangial conceptacles; and tetra/bisporangial conceptacles developed from small groups of subepithallial initials. Phylogenetic analyses based on the COI-5P, psbA, and rbcL datasets place B. astragaloi firmly within the Boreolithothamnion clade, supporting its identification and extending the known distribution of the species to the northwestern Pacific.

A crustose red alga, Lithophyllum neo-okamurae A.Kato, D.Basso, Caragnano, Rodondi, V.Peña & M.Baba, is reported a new record from Korea and its biogeographic distributions are extended in Korea. Lithophyllum neo-okamurae has been known as endemic species in Japan. Despite the resemblance between L. neookamurae and L. okamurae, our molecular and morphological analyses have revealed the simultaneous presence of both species in Korea. Although L. neo-okamurae and L. okamurae share morphological similarities, there are notable variations in gene sequences, with a range of 9.1-11.3% in psbA and 14.8-15.3% in rbcL. Specifically, while L. neo-okamurae is distributed throughout the entire coastline of Korea, L. okamurae is predominantly found in southern region. Furthermore, our analyses have revealed their detailed distributions in Korea.

Neoporphyra kitoi Ma. Abe, N. Kikuchi, Tamaki, Tom. Sato, Murase, Fujiyoshi & Mas. Kobayashi has been known as an endemic species in Japan. Its high temperature tolerance suggests that it could be advantageous for cultivation. In this study, we collected it from the Ulleungdo island, Korea and transferred it into Pyropia for a new combination, identified as Pyropia kitoi (Ma. Abe, N. Kikuchi, Tamaki, Tom. Sato, Murase, Fujiyoshi & Mas. Kobayashi) D.J. Kim, T.O. Cho & B.Y. Won comb. nov. based on morphological and molecular analyses. Pyropia kitoi is also reported as a new record species in the list of Korean macroalgal flora. Although we didn’t observe the emergence of new blades from the rhizoidal cells, which is a key character for this species, our molecular analysis of rbcL revealed that our samples from Korea were congruent with “Neoporphyra kitoi” from Japan and were nested within the clade of Pyropia. The gene sequence divergence between the Korean and Japanese samples was 0-0.2%.