Pseudorhabdosynochus inversus sp. nov. (Monogenea, Diplectanidae) from the halfmoon grouper Epinephelus rivulatus (Perciformes, Serranidae) off New Caledonia

Pseudorhabdosynochus inversus sp. nov. is described from three specimens found in a halfmoon grouper, Epinephelus rivulatus, from the external slope of the barrier reef, New Caledonia, South Pacific. The new species is characterised by the structure of its sclerotised vagina, which resembles that of P. epinepheli (Yamaguti, 1938) but has its primary chamber inverted, and by its measurements. The diplectanid fauna of E. rivulatus shows the same pattern as in other groupers, probably belonging to a clade in which fish species harbour both an abundant species of the ‘Pseudorhabdosynochus cupatus group’ (here P. calathus Hinsinger et Justine, 2006) and a rare species (here P. inversus).

Pseudorhabdosynochus bacchus sp. nov. (Monogenea, Diplectanidae) from Epinephelus coeruleopunctatus (Perciformes, Serranidae) off New Caledonia

Pseudorhabdosynochus bacchus sp. nov. (Diplectanidae) is described from the gills of the whitespotted grouper Epinephelus coeruleopunctatus collected off New Caledonia, South Pacific, and is the first monogenean reported from this fish. It has a characteristic quadriloculate male organ, with both cone and tube of similar short length (10–12 μm). The morphology of its sclerotised vagina, with two chambers of equal size, differentiates it from all other species of the genus. Other rare Pseudorhabdosynochus species and specimens of an undescribed species of Haliotrema (Ancyrocephalidae) were also found, but in insufficient number to allow description.