New records of the marine diatom parasites Lagenisma coscinodisci (Lagenismatales, Oomycetes) and Paulsenella kornmannii (Thoracosphaerales, Dinophyceae) in Korea

다국어 초록 (Multilingual Abstract)

This study presented the first record of two marine diatom parasites, Lagenisma coscinodisci (Oomycetes) and Paulsenella kornmannii (Dinophyceae), in Korea. Plankton samples were collected from Yongho Harbor, Busan, in March 2022, and diatoms infected by these parasites, Coscinodiscus wailesii by L. coscinodisci and Eucampia zodiacus by P. kornmannii, were isolated for morphological and molecular analyses. Both parasites exhibited developmental characteristics consistent with previous descriptions. The 18S rRNA gene sequences of L. coscinodisci (1,430 bp) and P. kornmannii (1,331 bp) were successfully obtained, with the latter being reported for the first time. Phylogenetic analysis placed L. coscinodisci within Oomycetes, clustering with Thraustotheca clavata, while P. kornmannii was positioned within Dinophyceae, closely related to P. vonstoschii. This study provides new insights into the biodiversity of parasitic protists in Korean waters and contributes the first molecular data for P. kornmannii.