One of 23 specimens of the Spadenose shark, Scoliodon laticaudus (Elasmobranchii: Carcharhiniformes: Carcharhinidae), necropsied for tapeworms in Mukah, Sarawak, in Malaysian Borneo between 2002 and 2003 was found to host a new genus and species of tetraphyllidean tapeworm belonging to the family Phyllobothriidae. Ruhnkecestus latipi n. g., n. sp. is described from 4 specimens, 3 prepared as whole mounts and 1 from which the strobila was prepared as a whole mount, and the scolex prepared for examination with scanning electron microscopy. The genus is unique among phyllobothriids in that each bothridium bears 1 anterior, 3 central, and 2 posterior facial loculi. Its microthrix pattern, proglottid anatomy, and host associations suggest that its affinities are with the Phyllobothriinae. Among the Phyllobothriinae it most closely resembles species of Paraorygmatobothrium in its possession of a scutellate neck and serrated microtriches on its proximal bothridial surfaces, as well as a tetralobed ovary and vitellaria that are interrupted by the ovary. This represents the first report of a tetraphyllidean tapeworm from the monotypic shark genus Scoliodon.