Introduction

Japetella diaphana reaches about twice the length of Bolitaena pygmaea and has larger eyes. The third arms of the male have slightly enlarged suckers, but no trace of a ligula has been found. No fully mature male, however, has ever been captured.

Brief diagnosis:

A bolitaenid ...

• without a hectocotylus (ie, neither arm III with a ligula).
• with relatively large eyes on short optic stalks.