The occurrence of the dinoflagellates belonging to the ciguatera-related genus Gambierdiscus is reported for the first time from the north-western Arabian Gulf and northern Red Sea in the Indian Ocean basin. Gambierdiscus yasumotoi was recorded from two sampling sites on the southern Kuwait coast, and co-occurrence of G. cf. belizeanus and G. yasumotoi was found also in the Gulf of Aqaba in Jordan. The morphology of cells is described on the basis of light microscopy and scanning electron microscopy examination.
