Pseudorhabdosynochus sulamericanus

Pseudorhabdosynochus sulamericanus is a diplectanid monogenean parasitic on the gills of the snowy grouper, "Epinephelus niveatus", the Warsaw grouper, "Epinephelus nigritus" and the Haifa grouper, "Epinephelus haifensis". It has been described by Santos, Buchmann & Gibson in 2000
, redescribed by Kritsky, Bakenhaster and Adams in 2015.
and again redescribed by Chaabane, Justine, Gey, Bakenhaster & Neifar in 2016.
Description.
"Pseudorhabdosynochus sulamericanus" 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 description by Kritsky, Bakenhaster & Adams in 2015 includes the following:
Diagnosis.
According to Kritsky, Bakenhaster and Adams (2015), "P. sulamericanus" is most similar to "P. firmicoleatus" based on comparative morphology of the vaginal sclerite, male copulatory organ, and haptoral elements. The vaginal sclerite of both species has a comparatively small basal chamber and a small secondary bulge of the tube that flares at its union with the vaginal vestibule. The sclerite of "P. sulamericanus", however, differs from that of "P. firmicoleatus" by having a slightly larger chamber and irregular sclerites associated with the distal tube.
Chaabane et al. redescribed the sclerotized vagina as consisting of slightly sclerotised funnel-shaped trumpet, followed by a short primary canal with thick wall. Its primary canal is surrounded by additional sclerotised material in its proximal part, which obscures internal relationships. The posterior end of primary canal is directed to primary chamber and the junction between the two structures is visible (in specimens from "H. niveatus") or not (in specimens from "H. haifensis"). The primary chamber is small, pear-shaped. The secondary canal (junction between primary chamber and secondary chamber) was not seen. The secondary chamber is spherical and heavily sclerotised. The accessory structure has an internal canal and is looping twice and inserted on the secondary chamber.
Hosts and localities.
Type-host and other hosts in the Western Atlantic.
The type-host of "P. sulamericanus" is the snowy grouper, "Epinephelus niveatus" (or "Hyporthodus niveatus") (Serranidae: Epinephelinae). The type-locality if off Ilhas Cagarras, Rio de Janeiro, Brazil. The species has also been recorded in the same host from off Cape Canaveral, Florida, and off Pensacola, Florida. It has also been recorded from another host, the Warsaw grouper, "Epinephelus nigritus" (or "Hyporthodus niveatus"), off Naples, Florida.
A transatlantic Monogenean.
In 2016, Chaabane et al. examined specimens of Haifa grouper, "Hyporthodus haifensis", from off Tunisia and Libya. They found specimens of monogeneans belonging to the genus "Pseudorhabdosynochus", and conducted a morphological comparison between newly collected specimens and those previously deposited in museum collections by other authors. Finally, they considered their specimens to be cospecific with "Pseudorhabdosynochus sulamericanus". They wrote "Our observation that "P. sulamericanus" infects unrelated host species with putatively allopatric distributions was unexpected given the very limited dispersive capabilities and the high degree of host specificity common to members of "Pseudorhabdosynochus". This transatlantic distribution raises questions with regard to phylogeography and assumptions about the allopatry of Atlantic grouper species from the Americas and Afro-Eurasia."