Mirocaris keldyshi gen. nov., sp. nov. is described from the Mid-Atlantic Ridge, TAG Location (26°09′N 44°50′W). The family Mirocarididae is proposed to include the new genus. The taxonomic position and distinguishing characters (presence of hook-bearing thoracic epipods and rudimentary appendix interna on pleopods 2–4) of the new family as compared to the other families of the superfamily Bresilioidea (Bresiliidae, Disciadidae, and Alvinocarididae) are discussed, and revised diagnoses for these families are provided.