Two new species of Macrobothridium (Cestoda : Diphyllidea) from rhinobatidelasmobranchs in the Gulf of Gabes, Tunisia, with notes on the status of the genus

As a result of an investigation of metazoan parasites of elasmobranch fishe s in the Gulf of Gabes, Tunisia, we discovered 2 new species of diphyllidea n cestodes. Macrobothridium euterpes n. sp. is described from the spiral in testine of Rhinobatos rhinobatos, and Macrobothridium syrtensis n. sp. from the spiral intestine of Rhinobatos cemiculus. Macrobathridium euterpes is distinguished from the only other species in the genus (Macrobothridium rhy nchobati) by the number of rostellar hooks, size, genital pore position, Va gina position, and ovary shape. Mncrabothridium syrtensis is distinguished from M. rhynchobati by the hook morphology, testis number, and overall size , and from M. euterpes by the number of rostellar hooks, testis number,geni tal pore position, vagina position, and ovary shape. These are the first 2 species added to the genus since its establishment in 1989. A standardized formula for representing the number and arrangement of rostellar hooks in d iphyllidean species is presented.