Native
4
Gyge branchialis is a parasite of the mud lobsters Upogebia deltaura and U. stellata and, occasionally, of the squat lobster Galathea squamifera. The larger female (up to 12 x 9 mm) is oval shaped with distinct pleon segments and small, uniramous pleopods. The uropods are small projections. The smaller male (up to 5 mm) has distinct pleon segments and small simple uropods.
This parasitic isopod inhabits the gill chamber of its host species, all three of which are widespread around Britain and Ireland, though in the case of Upogebia mostly sublittorally. There are intertidal records in mud at low water from south Devon and the Channel Islands.
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.
World Register of Marine Species (WoRMS): https://www.marinespecies.org/aphia.php?p=taxdetails&id=118216
Ocean Biodiversity Information System (OBIS) distribution map: https://mapper.obis.org/?taxonid=118216