Pseudorhabdosynochus regius n. sp. (Monogenea, Diplectanidae) from the mottled grouper Mycteroperca rubra (Teleostei) in the Mediterranean Sea and Eastern Atlantic.

Pseudorhabdosynochus regius n. sp. is described from the gills of the mottled grouper Mycteroperca rubra caught off Senegal, Tunisia and Libya (type-locality: off Dakar, Senegal). The species is distinguished from its congeners by the structure of its sclerotised vagina (length 26-35 μm), which exhibits a trumpet in continuity with the primary canal, a straight primary canal, and primary and secondary chambers included in a common sclerotised mass along the primary canal. The species is also characterised by small squamodiscs (length 20-40 μm) with 10-11 rows of rodlets. Its closest relatives (based on the structure of the sclerotised vagina) are species mostly found in the Mediterranean Sea and parasites on species of Mycteroperca. A second species of Pseudorhabdosynochus Yamaguti, 1958 is reported from the same host and localities but not described. A list of diplectanids from groupers in the Mediterranean Sea is provided. We point out that a recent article was not compliant with the new Article 8.5.3 of the International Code of Zoological Nomenclature; for this reason, three species, P. nhatrangensis Dang, Bristow, Schander & Berland, 2013, P. vietnamensis Dang et al., 2013 and P. brunei Dang et al., 2013, are invalid.