Metatrichoniscoides leydigii (Weber, 1880)


GB IUCN status: Data Deficient
GB rarity status: Nationally Rare

ID Difficulty



Metatrichoniscoides is a difficult genus and only male specimens of M. leydigii can be distinguished from M. celticus or preserved specimens of Trichoniscoides.  Identification is made by microscopic examination of male pleopods.

M. celticus is very small (up to 2.5mm long), pure white, entirely lacking ommatidia and the dorsal surface is covered in coarse tubercles.

J.P. Richards
J.P. Richards
J.P. Richards
Tom Hughes

Distribution and Habitat

It was first discovered in Britain in 1989 in the grounds of a garden centre in Oxford city where it occurred deep among peaty compost accumulated within stones and gravel (BISG Newsletter 28, pg.1).

In 2011 a second site was discovered in Kent, under a stone on peaty soil beside the River Medway. This habitat is akin to that noted in The Netherlands, where this species is native, suggesting that it may be an overlooked native species in eastern Britain (Gregory, 2012).

Subsequently, it has been recorded from an ornamental garden in Derbyshire (Richards, 2016) and the coast of the Ribble estuary, western England (Hughes, 2020).

It has been found associated with other soil dwelling trichoniscids, such as Haplophthalmus mengii, Trichoniscoides albidus and T. sarsi and T. saeroeensis.



Hughes, T. (2020) The occurrence of Metatrichoniscoides leydigii (Weber, 1880) (Isopoda: Oniscidea) on the Ribble Estuary, Lancashire. Bulletin of the British Myriapod & Isopod Group 32: 56-58.

Richards, P. (2016) A third British site for Metatrichoniscoides leydigii (Weber, 1880). Bulletin of the British Myriapod & Isopod Group 29: 34-36.

Gregory, S.J. (2012) The occurrence of two elusive woodlice, Metatrichoniscoides leydigii (Weber, 1880) and Trichoniscoides sarsi Patience 1908, in semi-natural habitat in Kent. Bulletin of the British Myriapod & Isopod Group 26: 37-40.

Gregory, S. (2009) Woodlice and Waterlice (Isopoda: Oniscidea & Asellota) in Britain and Ireland.  Field Studies Council/Centre for Ecology & Hydrology.



BRC Code