Sphaeroma rugicauda Leach, 1814
Members of the Lekanesphaera genus are pill isopods, the identification of which is somewhat more complicated than indicated in Naylor & Brandt (2015) and Hayward & Ryland (2017), not least because Naylor & Brandt do not include Lekanesphaera levii, whilst Hayward & Ryland leave out Lekanesphaera monodi. Although the patterning of tubercles on the pleotelson can be indicative of species, determination should be based on the presence and patterning of setae on the first pereopod of mature specimens (Jacobs 1987).
Small tubercles cover the surface of the pleotelson of L. rugicauda. The first pereopod has up to 30 smooth setae on the ischium, about 20 on the merus, and 2 (or occasionally 1) distodorsal setae on the propodus. Males are up to 10.0mm, females up to 7.5mm.
Distribution and Habitat
This species occurs on most coasts of Britain and Ireland in suitable habitat. It is found in estuaries and saltmarsh pools, under driftwood and burrowed into the mud cliffs of creeks.
Jacobs, B. J. M. 1987. A taxonomic review of the European, Mediterranean and NW. African species generally placed in Sphaeroma Bosc, 1802 (Isopoda: Flabellifera: Sphaeromatidae). Zoologische Verhandelingen 238, 3-71.
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.