Two new species of Dictyota (Dictyotales, Phaeophyta) are described from the Indian Ocean, Indonesia, and Papua New Guinea. Dictyota grossedentata is a procumbent species with large, irregularly placed marginal teeth, differing from all other prostrate species by its stout habit and conspicuous dentation. Dictyota grossedentata differs from other species characterized by dentate margins by its prostrate habit and by the lack of a single, conspicuous stupose base. Dictyota rigida is a stiff, completely erect species with a single point of attachment. Because of its stiff texture, it resembles D. Fastigiata Sonder and D. Suhrii Murray but differs by its unilayered medulla. Dictyota rigida also is compared with the other slender taxa. Taxonomic problems of the genus, such as substantial morphological variation and a lack of clearly discriminating characters, are considered. |