Pseudorhabdosynochus marcellus is a diplectanid monogenean parasitic on the gills of the malabar grouper, Epinephelus malabaricus.

The species are P. maaensis, P. malabaricus, P. manifestus, P. manipulus, P. marcellus, and P. maternus.

More precisely, for this species, the name marcellus refers to Tonton Marcel, a character of a locally well-known New Caledonian comic strip series, La Brousse en folie.

The type-host and only recorded host of P. marcellus is the malabar grouper, Epinephelus malabaricus (Serranidae: Epinephelinae).

The type-locality is near Nouméa, New Caledonia[1] where it was considered a very rare species (only 1% of the diplectanids found).