The Indo-West Pacific gobiid genus Taenioides Lacépède is further defined and one of the constituent species of the genus, T. purpurascens (De Vis 1884), is redescribed. Taenioides purpurascens is known only from the southeast coast of Australia and is compared to other species in the genus: T. anguillaris, distributed from India northeastward to China, and Japan, and southward to Australia; T. gracilis, distributed along the east coast of Africa and Madagascar to India, northeastward to Japan and southward to Australia; T. kentalleni, known only from Saudi Arabia and Japan; and T. snyderi, known only from southern Japan. Taenioides purpurascens is unique within the genus in having: the fewest dorsal-fin elements (41‒44 vs. 48‒72); the fewest anal-fin elements (34‒38 vs. 41‒65); the fewest vertebrae (27 vs. 28‒45); and a 2-4-2 arrangement of the barbels on the ventral surface of the head (vs. 2-2-2, 2-3-2, or 2-4-2-2). In morphometric comparisons with these other species, T. purpurascens is shown to have the shortest and deepest body. A key to these species is provided.