An accidental attachment of Elthusa raynaudii (Isopoda, Cymothoidae) in Etmopterus sp. (Squaliformes, Etmopteridae)

A female Elthusa raynaudii was found attached on the roof of the mouth facing inward in a lantern shark, Etmopterus sp. in Taiwan. This was backwards to all known cymothoid attachments in the mouths of fishes. This isopod naturally occurs in the gill chamber of fishes. The attachment must have occurred accidentally. This is only the fourth time this isopod has been collected in the northern hemisphere and the first for Taiwan and this host.