Trois nouveaux Heterocotyle (Monogenea, Monocotylidae) parasites branchiaux de Taeniura grabata (Euselachii, Dasyatidae) en Tunisie

Description are given for three Heterocotylina, gills parasites of Taeniura grabata collected from various locality of the tunisian coast: Heterocotyle mokhtarae n. sp., H. striata n. sp., H. forcifera n. sp. The haptor of H. mokhtarae and H. striata has numerous sinuous septal ridges and 1-1-2-3-3 configuration. The haptor of H. forcifera has only one sinuous septal ridge. H. mohtarae has a tubular penis, and an ejaculatory bulb three times as long as the penis. H. striata has a conic penis with an ovoide slide-shaped piece with a slightly striated edge. H. forcifera has an accesory piece with two jagged branches fused to the tubular penis. The limits of the criteria defining the genus Heterocotyle and the systematic importance of the characters used, the number of sinuous ridges on the septa of the haptor and the presence of an accessory piece associated with the copulatory apparatus, are discussed. Constant differences are evidenced for the number of sinuosities on the septal ridges between these three species. A key of the genus Heterocotyle is proposed.