Gambierdiscus dokdoensis sp. nov. (Gonyaulacales, Dinophyceae), a new benthic-epiphytic dinoflagellate from Dokdo, Korea: morphology and phylogeny

An epiphytic dinoflagellate belonging to the genus Gambierdiscus was isolated from macroalgae collected around Dokdo, East Sea of Korea, and a clonal culture was established. Morphological characterization revealed anteroposteriorly compressed cells (52.0 ± 3.7 μm in length, 87.4 ± 7.6 μm in width, 80.7 ± 6.1 μm in depth), a thecal plate formula of Po, 3′, 7′′, 6c, 6s, 1p, 5′′′, 2′′′′, a centrally located nucleus, and a distinct 1p plate morphology, including a length-to-width ratio of 1.38 ± 0.08. Phylogenetic analyses based on concatenated small subunit-large subunit rRNA gene sequences placed the Korean isolate within the clade comprising G. bagnisii, G. carolinianus, G. holmesii, G. polynesiensis, and G. silvae (Clade III). In the large subunit D8–D10 phylogeny, which provided the primary specieslevel molecular evidence, the Korean isolate clustered with Japanese strains previously referred to as Gambierdiscus sp. type 3 with maximum support (maximum likelihood, 100; Bayesian inference, 1.00), and the uncorrected p-distances between them were low (0.0019–0.0021). These results indicate that the Korean isolate and the Japanese type 3 strains represent the same previously recognized but undescribed species-level lineage. On the basis of combined morphological and molecular evidence, this lineage is described here as Gambierdiscus dokdoensis sp. nov. The present study established the first formal taxonomic record of Gambierdiscus from Dokdo, East Sea of Korea, and contributes to the documentation of Gambierdiscus diversity in temperate Korean waters.