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.

Abstract
1. INTRODUCTION
2. MATERIALS AND METHODS
    2.1. Morphological analyses
    2.2. Molecular analyses
3. RESULTS AND DISCUSSION
CRediT authorship contribution statement
Declaration of Competing Interest
ACKNOWLEDGEMENTS
REFERENCES

• Gwan Woung Kim(Department of Biological Science, Chosun University, Gwangju 61452, Republic of Korea)
• Tae Oh Cho(Department of Biological Science, Chosun University, Gwangju 61452, Republic of Korea)
• Boo Yeon Won(Department of Biological Science, Chosun University, Gwangju 61452, Republic of Korea) Corresponding author
• So Young Jeong(Australian Rivers Institute-Coast & Estuaries and Coastal and Marine Research Centre, School of Environment and Science, Nathan Campus, Griffith University, Nathan, Queensland, Australia)