Ligidium hypnorum (Cuvier, 1792)
GB IUCN status: Least Concern
Ligidium hypnorum is an attractively mottled woodlouse with a stepped body outline and antennal flagellum characteristically composed of numerous bead-like segments (otherwise only seen in the coastal Ligia oceanica).
It can be confused with the common Philoscia muscorum, which is of similar size and shape (but P. muscorum has just three elongated flagella segments).
Ligidium hypnorum occurs mainly south of The Wash and River Severn, being most abundant in south east England. It has not been recorded from Ireland.
[The NBN records from the north-east need to be verified, and are almost certainly erroneous.]
In south-east England it inhabits a wide range of waterlogged habitats, but further north and west, on the edge of its European range, it becomes restricted to semi-natural habitats, such as ancient woodland and fen carr.
It occurs among moss and leaf litter, within sedge and grass tussocks, or beneath dead wood and stones. It is a very fast woodlouse, and difficult to capture.
This summary is based on the detailed account in Gregory (2009).