First integrated characterization of Microcotyle pomatomi Goto, 1899 (Polyopisthocotylea: Microcotylidae) from the Bluefish Pomatomus saltatrix (Linnaeus) off Algeria, Western Mediterranean, with resolution of its historical synonymy.

The platyhelminth Microcotyle pomatomi Goto, 1899 was originally described from the gills of the bluefish, Pomatomus saltatrix (Linnaeus) collected in Newport, Rhode Island (USA). The original description was brief and lacked detailed morphological, anatomical, and molecular information. As a result, the species has long been the subject of several taxonomic studies, with historical records often attributed to different nominal taxa due to insufficient diagnostic features. In the present study, specimens of M. pomatomi were collected from the gills of Pomatomus saltatrix (Linnaeus) off the Algerian coast in the western Mediterranean, representing the first molecular characterization of this species in this region. Parasites were carefully examined, measured, and illustrated to provide a comprehensive morphological redescription. In parallel, molecular characterization was conducted using a partial fragment of the mitochondrial cox1 gene, and host identity was confirmed through analysis of gill tissue. The integration of morphological and molecular data allowed for a more precise identification and improved understanding of the species. The obtained cox1 sequence clearly supports the validity of M. pomatomi and distinguishes it from closely related congeners. Furthermore, our findings confirm the synonymy of several previously described species. Overall, this study clarifies the taxonomic status and phylogenetic position of M. pomatomi within the Microcotylidae.