Trichoniscoides is a difficult genus and only male specimens of T. saeroeensis (a predominantly coastal species) can be distinguished from T. helveticus or T. sarsi (the latter may also occurs on the coast of eastern Britain). Identification should be based on microscopic examination of male 2nd endopod.
All three are small (to 4 mm) creamy-white woodlice flushed with varying amounts of pinkish-orange. The dorsal surface is covered with weak tubercles and the eye is composed of a single pinkish-red ommatidum. All eye and body pigments are rapidly lost in alcohol, thus making preserved specimens difficult to separate from Metatrichoniscoides celticus or M. leydigii.
Distribution and Habitat
Although widely distributed around the entire coastline of Britain and Ireland, it is not confined to coastal habitats. It has been recorded up to 12km inland deep inside limestone caves and mines, and on the summits of limestone mountains.
None-the-less, it is typically found in the supralittoral zone associated with coastal erosion banks, sparsely vegetated shingle or salt marsh strandline. Here it tends to occur several centimetres below the surface, where damp peaty soil occurs and most easily collected by turning large partly embedded stones. It is often found with Haplophthalmus mengii.
This summary is based on the detailed account in Gregory (2009).