Trichoniscoides albidus (Budde-Lund in Meinert, 1880)

Common name

Rough Pygmy Woodlouse


GB IUCN status: Least Concern

ID Difficulty


The pygmy woodlice of family Trichoniscidae (and Styloniscidae) are readily distinguished from other woodlice by the shape of the antennal fagellum which comprises a tapered cone (of indistinct segments) bearing a terminal bristle.

In size, shape and colour this small woodlouse (to 4 mm body length) is similar in appearance to the ubiquitous Trichoniscus pusillus agg.  Trichoniscoides albidus differs in having a coarsely tuberculate body surface, eye comprising a single ommatidium and all eye and body pigments are rapidly lost in alcohol (retained in T. pusillus agg.). Thus preserved specimens are difficult to separate from Metatrichoniscoides celticus or M. leydigii.

Video footage of a live specimen of this tiny woodlouse by Duerden Cormack can be viewed here. Note the video begins with a specimens of Trichoniscus pusillus agg. with T.albidus making its appearance after 9 seconds. 

J.P. Richards
J.P. Richards
Keith Lugg
Jane Thomas
Warren Maguire
Duerden Cormack


In southern and eastern England Trichoniscoides albidus widespread, but probably under-recorded. It appears to be rare (and very under-recorded) in Ireland with a handful of widely scattered records. 


It inhabits damp friable soils in a wide range of habitats, including wet deciduous woodland, alluvial meadows, banks of streams and ditches, seepages on ‘soft’ slumping cliffs, and occasionally churchyards and farmyards.

It is elusive and found with difficulty on the underside of embedded stones and dead wood or amongst damp rubble. It is typically found with Trichoniscus pusillus agg., T. pygmaeus and Haplophthalmus spp. 

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.

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