Stenosoma are elongated Idoteids with no distinct pleon somites, so that the pleon and the telson are completely fused. S. acuminatum has a long, flattened cylindrical body up to 25 mm long and 5 mm wide. The pleotelson narrows gradually from halfway to an acute point. The coxal plates are small and not easily visible from above. It is green-brown in colour.
Distribution and Habitat
The shape and colour of this species is similar to the air bladders of the seaweed Halidrys siliquosa (Sea Oak), and it lives among the fronds of this species. It is restricted to southern and western coasts of Britain (as far as south-west Scotland) and Ireland, though it is poorly recorded on the NBN map.
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.