FAMILY MALACOLEPADIDAE HIRO, 1937
Diagnosis: Parasitic inside bivalves; without shell plates; orifice large; first and second cirri short, and mandibles with six or seven teeth.
Comment: Arcalepas and Malacolepas are found attached to the inside of the shells of the bivalves Arca navicularis Bruguière, 1789 and Cucullaea labiata, (Lightfoot, 1786) respectively.
Arcalepas Jones & Morton, 2009 (one species)
Malacolepas Hiro, 1933 (one species)