Rainfordia opercularis was described in 1923 from a single specimen taken in Edgecumbe Bay, Queensland, Australia. The species is rare in museum collections, and the larvae have not been described. In 1999, two settlement-stage larvae (20–21 mm in standard length) were collected in light traps set off Lizard Island, Great Barrier Reef, Queensland. The smaller of the two has one thin, flexible, extremely elongate dorsal-fin spine encased in a pigmented sheath. The larger specimen lacks an elongate dorsal-fin spine and exhibits caudal-fin pigment characteristic of adults. A combination of features in one or both of the settlement-stage larvae support the placement of Rainfordia in the epinepheline-serranid tribe Liopropomini: presence of an elongate, filamentous dorsal-fin spine serially associated with the first dorsal-fin pterygiophore; presence of a spine on the inner preopercular ridge; presence of dense pigment on the frontals; absence of an elongate spine at the angle of the preopercle; and absence of supraorbital spination.