Swordtip squid

Marine cephalopod mollusc with mantle moderately stout and elongate, slender in mature males, which have a ridge along ventral midline. Fins rhombic, attaining 70% of mantle length in adults, their posterior margin slightly concave. Tentacular clubs expanded, lanceolate. Arm sucker rings with 8 to 11 distinct, squared, truncate teeth in distal, smooth or with rudimentary denticles proximally; slightly more than 1/2 of left arm IV hectocotylized by enlargement of about 50 pairs of sucker stalks into swollen papillae, each with a minute rudimentary sucker on the tip; papillae slightly larger in ventral row; a fusiform photophore on each side of rectum. Maximum mantle length 40 cm.