Description of Pseudorhabdosynochus justinei n. sp. (Monogenea: Diplectanidae) and redescription of P. vagampullum (Young, 1969) Kritsky & Beverley-Burton, 1986 from the gills of the longfin grouper Epinephelus quoyanus (Valenciennes) (Perciformes: Serranidae) in Dapeng Bay, South China Sea.

Pseudorhabdosynochus justinei n. sp. is reported and described from the gills of the longfin grouper Epinephelus quoyanus in Dapeng Bay, South China Sea off the town of Nan'ao, Shenzhen, Guangdong Province, China. P. justinei n. sp. is characterised by the presence of a male copulatory organ (MCO) composed of a moderately quadriloculate organ, a short cone and a long, variable internal tube, and a sclerotised vagina comprising anterior 'trumpet' with a characteristic sclerotised ring, slightly medially curved canal, heavily sclerotised principal chamber and star-shaped lateral structure with accessory chambers. It is differentiated from the most similar species, P. caledonicus Justine, 2005, by the absence of a thinly sclerotised posterior tube of the MCO and by the size and morphology of the sclerotised vagina. P. vagampullum (Young, 1969) is redescribed based on specimens collected from the same species of host and locality as P. justinei n. sp. In comparison with the original description by Young [Young, P. C. (1969). Journal of Helminthology, 43, 223-254] and the redescription by Justine [Justine, J.-L. (2005a). Systematic Parasitology, 62, 1-37; (2005b). Systematic Parasitology, 62, 39-45] based on old museum material, the new specimens of P. vagampullum clearly showed the internal anatomy of the terminal genitalia, especially the sclerotised vagina, consisting of a distal, cylindrical canal with an anterior 'trumpet' continuing as an unsclerotised, curved, bulb-shaped vaginal pore, a conical principal chamber and a star-shaped lateral structure with an accessory chambers leading to the seminal receptacle via a fine, unsclerotised duct.