Crustaceans and Marine Heterobranchia: A New Symbiotic Relationship in the Mediterranean Sea

Abstract

The “solar-powered” Elysia timida (Risso, 1818) is an endemic Mediterranean sacoglossan living in rocky substrates at shallow water. During a scuba dive, one E. timida was photographed and collected. The observation revealed the presence of a small crustacean of the Pinnotheridae family. It was not possible to assign the crustacean to a genus, but it shares typical ecological and external morphological features with other Pinnotherinae species. This is the first report of a pea crab hosted by a non-shelled Heterobranchia and the first case of a symbiotic association between crustaceans and marine Heterobranchia reported in the Mediterranean Sea.