Pseudorhabdosynochus williamsi is a diplectanid monogenean parasitic on the gills of the rock hind, Epinephelus adscensionis.

Dr. Williams was one of the investigators who collected the voucher specimen (a paratype of P. monaensis) of this species from rock hind in Puerto Rico.

P. williamsi most closely resembles P. justinella and P. meganmarieae based on the comparative morphology of the respective vaginal sclerites.

[1] The type-host and only recorded host of P. williamsi is the rock hind, Epinephelus adscensionis (Serranidae: Epinephelinae).

The type-locality and only locality is ca 40 miles offshore from St. Andrews Bay, Panama City, Florida.