GB rarity status: Nationally Scarce
This is an attractively mottled pill-woodlouse (to 9mm). It shares its distinctive mottling and the dark patch on the 7th epimera with A. pulchellum and females can be difficult to separate. A. vulgare is never as attractively mottled, and lacks the dark patch on the 7th epimera (See Gregory & Richards, 2008).
Distribution and Habitat
This is a very rare woodlouse, known from cluster of sites in the English Lake District, the Pennines and the Welsh/English border counties. It is probably under-recorded. It is exclusively associated with semi-natural habitats, typically in hilly areas, including ancient deciduous woodland, rough and/or shady grassland and grikes in limestone pavement.
Although usually found under moss carpets and stones, amongst scree or within red-rotted timber, it can be beaten from shrubs and may occur under loose bark and within rot holes high on mature trees. Alexander (2010) provides some additional comments on its habitat associations.
This summary is based on the detailed account in Gregory (2009).
Gregory, S. (2009) Woodlice and Waterlice (Isopoda: Oniscidea & Asellota) in Britain and Ireland. Field Studies Council/Centre for Ecology & Hydrology.
Gregory, S. & Richards, P. (2008) Comparison of three often mis-identified species of pill-woodlouse Armadillidium (Isopoda: Oniscidea). Bulletin of the British Myriapod & Isopod Group, 23: 9-12.