Abstract

Four molluscan species‒Amicula gurjanovae Yakovleva, 1952, Nipponacmea nigrans (Kira, 1961), Coralliophila carnosa Kosuge, 1986, and Sepia furcata Ho & Lu, 2005‒are reported for the first time from Korean waters. Within the genus Amicula, only two valid species are currently recognized worldwide: A. amiculata (Pallas, 1788) and A. gurjanovae Yakovleva, 1952. A. gurjanovae is considered a rare species, previously known only from the southern Kuril Islands and southern Sakhalin. N. nigrans is distinguished by its non-protruding apex, dense riblets, and gray pigmentation on the snout and sides of the foot. C. carnosa is similar to C. pulchella and C. morishimai, both known to occur in Korean waters. However, it can be distinguished by its more slender shell, less angular shoulder, and more numerous and pronounced spiral cords. The S. furcata specimen identified in this study was slightly larger than in the original description and exhibited an arm formula of 2 > 3 > 4 > 1. For each species, we provide detailed morphological descriptions, high-resolution images, and partial mitochondrial cox1 sequences as DNA barcode references.