A new species of genus Acanthobothrium Blanchard, 1848 is described from the spiral intestine of Pastinachus cf. sephen (Forsskal, 1775) from Iranian coasts of the Gulf of Oman. The morphological characteristics of specimens were analyzed with light and scanning electron microscopy. Acanthobothrium chabahariense n. sp. is a category 1 species (with <15mm total length, <50 proglottids, <80 testes and a symmetrical ovary) together with 48 other species. The new species was compared with species from the Western Indian Ocean and those reported from Pastinachus. It is distinguished from the other species from the region within the genus by a combination of the following morphological features: total length, number of proglottids, hook length, number of testes and ovarian lobe length. Pastinachus sephen is a complex group still with no taxonomic resolution; therefore, the identity of the host in this study area is in question. Because of the molecular study of specimens from the Gulf of Oman did not completely correspond with P. sephen since they were introduced as P. cf. sephen. This brings the total number of species of Acanthobothrium from Pastinachus to 11 and the total number of Acanthobothrium species described from the Persian Gulf and the Gulf of Oman to seven. In addition, an identification key to the Acanthobothrium species occurring in the Pastinachus species was provided.
