• Animal Systematics, Evolution and Diversity
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• v.39 no.4
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• pp.284-288
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• 2023

In this article, a phyllidiid nudibranch which is distributed widely in the Indo-Pacific region, Phyllidia varicose Lamarck, 1801, is reported based on a specimen collected from Seopseom Islet, Jeju Island, Korea. This species is characterized by bluish-gray dorsal tubercles with a yellow cap and three distinct ridges consisting of dorsal tubercles going from the anterior to posterior region, the presence of bluish-black pigment between the dorsal ridges, and a characteristic black longitudinal stripe along the midline of the sole. In this study, we provide a key to species belonging to the genus Phyllidia discovered in Korea, the morphological descriptions, photographs, and a sequence of partial mitochondrial cytochrome c oxidase subunit I of P. varicosa. Currently, four species of the genus Phyllidia have been reported to be present in Korea, including P. varicosa.