Mantle wide, cup-like, thick-walled, semigelatinous, fused with head in nuchal region. Head small, narrower than mantle. Only anterior part of nuchal cartilage present. Eyes very small. Fin very large, widely heart-shaped or transversely-oval, fin width approx. twice fin length. Arms short, subequal, with 2 rows of toothless suckers. Tentacles long, thick, robust, narrowing toward the end. Club not differentiated, without protective membranes and keel, beset with minute suckers in many (8-20) rows. No fixing apparatus. Buccal membrane weakly developed, with 7 lappets, connectives to 4th arms attached ventrally. Funnel cartilage oval, without tragus and antitragus. No photophores. Gladius strongly reduced, with rather wide fan and, in one species, thin rachis. ML up to 18 cm. Larvae with very short conical arms, tentacles long, with thick stalks, also conical, fin shorter than half of ML, tentacular suckers in approx. 6 rows.
The only described species, Promachoteuthis megaptera Hoyle, 1885, is known from the Northwestern Pacific. An undescribed species reported for the subantarctic South Atlantic and the SE Pacific. All species predominantly abyssopelagic.