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.
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.
Pseudorhabdosynochus sulamericanus