Five New Records of Endophytic Fungi Isolated from Sargassum spp. in Korea.

Five endophytic fungal species were isolated from the brown macroalgae Sargassum muticum and Sargassum thunbergii collected from coastal regions of Korea. The isolates were identified based on morphological characteristics and phylogenetic analyses using combinations of internal transcribed spacer (ITS), large subunit ribosomal RNA (LSU), β-tubulin (TUB), translation elongation factor 1-alpha (TEF), calmodulin (CaM), and RNA polymerase II second largest subunit (RPB2) gene sequences. The identified species were Hypoxylon cinnabarinum, Neopestalotiopsis asiatica, Allophoma hayatii, Sclerostagonospora cycadis, and Aspergillus occultus. Phylogenetic analyses based on multilocus sequence data supported the taxonomic placement of all isolates, and their morphological characteristics were consistent with those of previously described species. This study represents the first report of H. cinnabarinum, N. asiatica, A. hayatii, S. cycadis, and A. occultus in Korea. These findings expand the known diversity of endophytic fungi associated with Sargassum species and provide baseline taxonomic information for future studies of seaweed-associated fungal communities in Korean coastal ecosystems.