Fischer, 1895
Mantle narrow, cup-like, with acute tail. Fins in larvae and juveniles tongue-shaped or oval, in adults semicircular, not joined and not reaching mantle end. Arms rather short but strong, 1-3 pairs with 2-5 pairs of hooks, 4th pair barren, without hooks (except in mature males). Tentacles long and thin; club compact, barely widened, in larvae with 1 row of large and 3 of small suckers; in adults with 4 rows of suckers; no hooks. Gladius narrowed caudally into acute needle.
Photophores: 8 in mantle cavity (2 large round near anus; 2 oval near brachial hearts, 3rd between the latter; 2, next to each other at level of stomach; and 1 very small ventrally on conus of gladius); 15 (rarely 14) on ventral and caudal parts of the eyeball (small and large, of variable structure, located in strict order, some large ones with green metallic glitter); 4 under skin on tentacular stem.
Anal and brachial-heart photophores begin to develop at ML approx. 2.0-2.5 and 1.5 mm resp., all photophores in the mantle cavity developing at ML >10 mm. First eye photophores appearing at ML 2 mm, at 5 mm they number 9-10. Their distribution, as well as the semicircular fins, acute tail end, tentacles with a compact bunch of very small suckers at the tip, and naked 4th arms, are characteristic for larvae and juveniles. No pink patches on tentacle in larvae. Egg size 1.0 mm. ML up to 25, rarely to 30 mm.
A circumglobal species, represented in the Atlantic by the subspecies Pterigioteuthis giardi giardi. Another Atlantic species, Pterigioteuthis gemmata Chun, 1908, distinguished by the presence of hooks (2-8, mostly 3-7) only in a ventral row on 1st-3rd arms, 2 rows of very small suckers on 4th arms (noticeable in juveniles in side view), and 14 (rarely 15) eyeball photophores; also circumglobal but predominantly anti-equatorial species, represented by a series of local forms.