Leptoplana limnoriae is a polyclad flatworm described from several specimens collected, symbionts of the introduced woodboring isopod Limnoria spp. from the California Yacht Club, Los Angeles Harbor, in 1950, by Hyman (1953). The origin of this flatworm is unknown, as is that of its hosts, probably Limnoria quadripunctata and L. tripunctata (Hyman 1953; Carlton 1979).