Key to families of Oplophoroidea

1. Second maxilla with elongate proximal endite lacking submarginal papilla and lamina (Fig. 7C); first maxilliped with two-segmented endopod at least two times as long as distal endite (Fig. 7D).......................................... Hymenodoridae fam. nov.

- Second maxilla with proximal endite bearing papilla and submarginal lamina (Fig. 7G, H, L, M); first maxilliped with three-segmented endopod (if two-segmented then as long as distal endite) (Fig. 7I, N)..........................................................................2

2. Second maxilliped with distal segment subtriangular and attached diagonally to preceding segment (Fig. 7O) ............................................................................................................................................................ Acanthephyridae Spence Bate, 1888

- Second maxilliped with distal segment suboval and attached almost transversely to preceding joint (Fig. 7J) ........................... .............................................................................................................................................................................. Oplophoridae Dana, 1852