The poorly known bopyrid isopod Bopyrophryxus branchiabdominalis Codreanu, 1965 is redescribed based on newly discovered material obtained from hermit crab hosts from several Indo-Pacific localities. The genus Bopyrophryxus Codreanu, 1965 is found to be closely related to the pseudionine genus Asymmetrione Codreanu, Codreanu, & Pike, 1965, with which it shares many characters of both males and females. The subfamily Bopyrophryxinae Codreanu, 1965 is found to be synonymous with the Pseudioninae Codreanu, 1967, although the junior synonym is maintained as the correct name of the taxon because of its extensive use in the literature.