A. acanthoderma reaches a rather large size. The largest specimen known has a mantle length of 78 cm and long, slender tentacles. In one squid (45 cm ML) the tentacles were over 12 times longer than the mantle (i.e., about 5.5 m)(Tsuchiya and Okutani, 1993). The most distinctive feature of this species is the presence of very small, pointed cartilagenous tubercules over the surface of the head, mantle and arms.

Figure. Ventral view of A. acanthoderma, mature male, 65 cm ML, Gulf of Mexico. Note the extremely thin, long tentacles and the long arms. Photograph by Jesse Wicker.

Brief diagnosis

An Asperoteuthis ...

• with tiny, pointed tubercules in skin.
• with a Y-shaped groove in the funnel locking-apparatus.