This taxonomic study sought to detect and describe diatom species not yet recorded in Korea. The study was conducted at three islands located off the western coast of Korea, Wido Island near Buan, Wonsando Island near Boryeong and Dekjeokdo Island near Incheon. Diatoms were collected from the bottom, stone, macrophytes and other substrates in water bodies, which are affected by seawater. Fifteen naviculoid taxa are described. Of these, 13 are novel to Korea. The genus Navicula has nine species; Navicula alineae Lange-Bertalot, N. ammophila Grunow, N. cariocincta Lange-Bertalot, N. elegantoides Hustedt, N. longicephala Hustedt, N. normaloides Cholnoky, N. notha Wallace, N. novaesiberica Lange-Bertalot, N. riediana Lange-Bertalot & U. Rumrich. The genus Craticula has four species; Craticula buderi (Hustedt) Lange-Bertalot, C. halophila (Grunow) D.G. Mann, C. riparia (Hustedt) Lange-Bertalot and C. riparia var. mollenhaueri Lange-Bertalot.

• Gyeongje Joh(Department of Environmental Science and Engineering, Inje University) Corresponding author