A Rare Collection of a Small Species of Gymnodoris (Nudibranchia : Polyceridae) Held Alive by the Chelipeds of the Crab, Lybia hatagumoana (Brachyura : Xanthidae), from the Bottom off Kanayama Bay, Kii, Japan

Abstract

A small nudibranch species Gymnodoris sp., is described. The specimens were found being held alive between the fingers of the chelipeds of two different individuals of a xanthid crab, Lybia hatagumoana Sakai, 1961, obtained from 62 m depth off Kanayama Bay, Kii, Japan. The nudibranch, when separated from the host crabs, moves very rapidly like a turbellarian worm, but internally it displays a radula characteristic of the genus Gymnodoris.