Euprymna megaspadicea n. sp. collected from Nago Bight, Okinawa Island, Japan, is described. This species is characterized by its small size compared with its congeners, and by having four rows of suckers on all arms, arm II longer than the other arms and a hectocotylized left arm I in males. Modification of the hectocotylus affects almost the whole length of the arm, and is characterized by the fusion of all sucker pedicels giving the arm a peculiar massive, wavy and twisted appearance
