Pseudorhabdosynochus yucatanensis
Pseudorhabdosynochus yucatanensis is a diplectanid monogenean parasitic on the gills of the red grouper, "Epinephelus morio". It was described by Vidal-Martínez, Aguirre-Macedo & Mendoza-Franco in 1997 and redescribed by Kritsky, Bakenhaster and Adams in 2015. Description. "Pseudorhabdosynochus americanus" is a small monogenean. The species has the general characteristics of other species of "Pseudorhabdosynochus", 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. 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 includes a sclerotized part, which is a complex structure. The redescription by Kritsky, Bakenhaster & Adams in 2015 includes the following: Kritsky, Bakenhaster & Adams (2015) wrote that "examination of the holotype, three paratypes, and voucher specimens from red grouper off Florida and Mississippi indicated that the original description of "P. yucatanensis" was based on specimens representing two distinct species of "Pseudorhabdosynochus"", namely "P. yucatanensis" "sensu stricto" and "P. justinella" Kritsky, Bakenhaster & Adams, 2015. They considered that "P. yucatanensis" (s. s.) most closely resembles "P.  meganmarieae" Kritsky, Bakenhaster & Adams, 2015 in the comparative morphology of their vaginal sclerites. Hosts and localities. The type-host of "Pseudorhabdosynochus yucatanensis" is the red grouper, "Epinephelus morio" and no other host has been mentioned. The type-locality is off Progreso, Yucatan, Mexico. Other localities include various places off the Yucatan Peninsula, Mexico [Celestun, Progreso, Sisal, Chelem, Telchac, Chuburna, Chicxulub, and Rio Lagartos (all Yucatan State), Campeche (Campeche State), and Chiquila (Quintana Roo State), Florida Middle Grounds, Gulf of Mexico, and an artificial reef in the Gulf of Mexico off Mississippi.