H. bonnellii is the type species of the genus. It reaches a rather large size (33 cm ML, 119 cm total length) for a histioteuthid. Its uneven distribution and variation in characters normally considered stable within species suggests that a number of separate populations exist.

Brief diagnosis

• with three series of photophores on arms III.
• with three large, dark, round photophores on the ventrolateral corner of the head.