Limnoria are small (up to 3-4 mm) but distinctive wood-boring marine isopods. The three species that have been recorded on British and Irish shores can be distinguished by the patterning of raised areas on the fifth pleonite and on the pleotelson, though these can be hard to discern.
L. quadripunctata can be distinguished from the other species by the presence of a Y-shaped 'carina' on the fifth pleonite and by two pairs of tubercles on the pleotelson.
Distribution and Habitat
L. quadripunctata occurs on southern and western British coasts (Jones 1963), from the Isle of Man to Kent. There are also records from the east coast of Northern Ireland. Where it co-occurs with L. lignorum, it occupies the middle zone of wood pilings, whereas L. lignorum occurs at the base of pilings and sublittorally.
Jones, L. 1963. The geographical and vertical distribution of British Limnoria [Crustacea: Isopoda]. Journal of the Marine Biological Association of the U.K., 43, 589-603.
Naylor, E. & A. Brandt. 2015. Intertidal Marine Isopods. Synopses of the British Fauna (New Series), No. 3. Field Studies Council, for The Linnean Society of London.