GB rarity status: Nationally Scarce
Trichoniscoides is a difficult genus and only male specimens of T. helveticus can be distinguished from T. sarsi or T. saeroeensis. Identification is made by 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
First discovered in Britain in 1990 (BISG Newsletter 28). It is known from scattered localities across central southern England, but it is likely to be considerably under-recorded; Records north of this cluster need verification.
It has a strong preference for semi-natural habitats with undisturbed friable calcareous soils, including short-turf grassland, rank grassland, mixed scrub and deciduous woodland.
Specimens are typically found with difficulty by searching the underside of large stones partially embedded into soil, or from amongst chalky soil or limestone rubble. It is often associated with other soil-dwelling trichoniscids, primarily Trichoniscus pygmaeus.
This summary is based on the detailed account in Gregory (2009).