Pseudorhabdosynochus epinepheli

Pseudorhabdosynochus epinepheli is a small monogenean, about half a millimetre in length. Adults are hermaphroditic. The species has the general characteristics of other diplectanids, with a flat body and a posterior haptor, which is the organ by which the monogenean attaches itself to the gill of is host. The haptor bears two squamodiscs, one ventral and one dorsal, which are made up of numerous rows of rodlets.

The reproductive organ include a single ovary and a single testis. The sclerotized male copulatory organ, or "quadriloculate organ", has the shape of a bean with four internal chambers, as in other species of Pseudorhabdosynochus. The vagina also includes a sclerotized part, which is a complex structure. The sclerotised vagina comprises an anterior trumpet, followed by a primary canal, a primary chamber, a secondary canal, a secondary chamber and an accessory structure. The trumpet is in continuity with the unsclerotised vagina. The primary canal is thin-walled, with regular diameter and wide lumen, and is coiled once. The primary chamber is heavily sclerotised, and complex in shape: a pear-shaped cavity continued as a heavily sclerotised cylinder arising from its thinner, posterior part; the cylinder curves and runs parallel with the longitudinal axis of the pear-shaped cavity; the cylinder continuous with primary canal. The secondary canal is thin, with an indistinct central lumen. The secondary canal is inserted into the cylinder of the primary chamber. The secondary chamber is continuous with the secondary canal, sclerotised, and elongate, ventral to and much smaller than the primary chamber. The accessory structure is small, inserted into the anterior extremity of the secondary chamber. The external and internal surfaces of the primary and secondary chambers are smooth.^[1][2]