GLOEOPHYCUS koreanum gen. et sp. nov., a red alga belonging to the Gloiosiphoniaceae, is described from the West Coast (Yellow Sea Coast) of Korea. The thallus is uniaxial, with tetrastichous pericentral cells giving rise to determinate and indeterminate branches and corticating filaments. The procarp comprises a 3-celled carpogonial branch and a 2-celled auxiliary cell branch borne on an intercalary supporting cell of a fertile branch, the auxiliary cell being terminal and fusing directly with the carpogonium after fertilization. Two or 3 spermatangia are produced by each spermatangial mother cell. Tetrasporangia are not known. The new genus most closely approximates Thuretella but differs in the terminal position of the auxiliary cell, the development of the auxiliary cell branch after the formation of the carpogonial branch and the lack of an involucre surrounding the carposporophyte.