Morphological And Molecular Approaches To The Diversity Of Digenean Parasites In Two Sparid Fishes, Diplodus Vulgaris (g, 1817) And Sparus Aurata L. 1758 Along The Algerian Coasts Of The Western Mediterranean

Résumé: The present study focuses on the application of an integrative approach to the identification of trematode parasites recovered in two sparid fish species, Diplodus vulgaris (Geoffroy Saint- Hilaire, 1817) and Sparus aurata L. along the Algerian coasts of the Western Mediterranean, an unexplored area regarding fish helminth diversity. A total of 810 fishes (390 D. vulgaris and 420 S. aurata), were examined at three localities (off Bouzedjar, Algiers and Annaba). Profiting from large sample sizes and fruitful collaboration, we have generated a sequence database for the mitochondrial cox1 and nuclear ITS1-5.8S-ITS2 gene cluster and/or partial 28S rDNA sequences for a total of 15 trematode species. Detailed morphological characterisation is provided for these species representing 11 families: Opecoelidae (5 species of 2 genera); Acanthocolpidae, Aephnidiogenidae, Aporocotylidae, Derogenidae, Hemiuridae, Heterophyidae, Lepocreadiidae, Monorchiidae, Strigeidae (one species each), and a single species of the Aspidogastridae (Subclass Aspidogastrea). Three species new to science were described from the studied material: Macvicaria gibsoni, Rima, Marzoug, Pérez-del-Olmo, Kostadinova, Bouderbala & Georgieva, 2017; a new species of Cardicola; and a putative new species of Monorchis. Linking sequence data with detailed morphological assessments helped clarify species delineation within the species complexes of two groups, i.e. the "crassigula" species complex of Macvicaria and "Monorchis parvus" species complex of Monorchis. Morphological and molecular insights into the diversity of marine fish digeneans are provided in the light of phylogenies for the Opecoelidae, Aporocotylidae, Hemiuroidea, and a broadly built phylogeny for the Digenea. The large number of trematode species recovered in the two fish hosts and the finding of three species new to science suggest that the diversity of these parasites in the region may be higher than currently known. The novel sequence data gathered during the present study will advance further studies on the diversity, host ranges and distribution of these important parasites. The present results highlight the importance of the application of morphological and molecular methods in the assessment of parasite diversity in the Mediterranean.

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