A marine brown alga was collected from Geoje, located on the southern coast of Korea. This species shares the generic features of Dictyota and is morphologically characterized by the combined features of erect or prostrate thallus with smooth margin, dichotomous to subdichotomous branches not twisted at the terminal part, absence of surface proliferations, 1-3 cell layered cortex and unilayered medulla, and lack of involucrum in sporangia subtended by a single stalk cell. In a phylogenetic tree based on rbcL sequences, this species nests in the same clade with Dictyota bartayresiana. The genetic distance between both sequences within the clade was calculated as 1.2%, considered to be within the intra-species range for the genus. Based on these morphological and molecular analyses, this Korean alga is identified as D. bartayresiana described originally from the West Indies. This is the first record of D. bartayresiana in Korea.