(Chun, 1900)
Fin in larvae oval or triangular, with straight posterior margin; in adults diamond- or broadly heart-shaped, reaching midpoint of mantle anteriorly, posteriorly not tapering into a tail. All arms in larvae and juveniles approximately equal, short, in subadult and adult males (ML >80-90 mm) ends of 2nd and 3rd arm pairs very elongated (2nd arms may be 2-3 times as long as the mantle, 3rd much shorter), tapering, whip-like and devoid of suckers. In females the ends of 2nd-3rd arms are filiform but not lengthened.
Photophores: 5 in one row on ventral side of eyeball, central one largest even in early larvae; 2 on tentacular stem (at base and at middle); 10 in mantle cavity on internal organs: 2 near rectum, 5 at level of branchial hearts (3 large along midline, 2 smaller at sides); 3 merged together in caudal part of mantle cavity. In larvae only 6 noticeable: 2 round near rectum, 2 oval near midline, and 2 round at sides at level of branchial hearts (latter lacking in earliest larvae).
On 2nd and 3rd arms in adult males, one (on 2nd) or two (on 3rd) long rows of small photophores along base of lateral keel, through whole length of 2nd and in distal half of 3rd arm (lacking in juveniles). No large globular photophores at arm ends, nor caudal photophore. ML in males up to 19 cm, females smaller, up to 11 cm. Larvae were described as Asthenoteution planctonicum Pfeffer, 1912. "Onychoteuthis lorigera" was described from an adult male, Lycoteuthis diadema from an immature female.
A nerito-oceanic species, very abundant off Namibia and over Walvis Ridge. Adults in near-bottom layer on the slope. Adult males much rarer than females.