[1] Sibitrema poonui was described based on a single specimen from the bigeye tuna Parathunnus sibi (currently named Thunnus obesus [2](Scombridae), and designated as the type species of the genus.

[5][3] Sibitrema poonui was described based on 48 specimens from the gills of Cybiosarda elegans and Euthynnus alleteratus off Australia.

The differences between the Hawaiian and Australian populations were not significant, especially in view of the identical structure of the genital atrium, the clamps, the hooks and the vaginae.

The digestive organs include an anterior mouth, a pharynx larger than buccal suckers, a long wide oesophagus without diverticula and a posterior intestine that bifurcates in two lateral branches.

The reproductive organs include an anterior genital atrium armed with a single circle of curved terminally bifurcated spines, one row of ventrolateral vaginal openings on each side of the body behind the level of gonopore, each opening surrounded by muscles, a foldedovary and numerous large irregularly shaped testes pre, para and post-ovarian.