Porcellionides cingendus

CRUSTACEA > MALACOSTRACA > ISOPODA > Oniscidea > Crinocheta > Porcellionidae

This is an attractive, medium-sized, up to 9mm long woodlouse with a stepped body outline and antennal flagella with two, rather than three, segments. The body colour and general appearance is varied with individuals having shades of yellow, red or brown that intermix to give different mottled effects when mature. Juveniles are equally attractive, but with a more uniform colour. Although brightly coloured, the dorsal surface is rather dull in comparison to some species where the body is noticeably shiny. At first sight, they could be confused with Philoscia muscorum, except that species has three flagella segments.

The narrowing of the body between the pereion and pleon, coupled with antennae that have two rather than three flagella segments, are combined characters only associated with Porcellionides, of which there are just two British species. Another good identification aid for this particular species are the transverse lines or ridges that run across the rear portion of each segment of the pereion separating a narrow smooth front side from the rough rear side. This detail is particularly useful when looking at juveniles like the couple featured below where the stepped body outline is far less obvious than it is in adults.

Porcellionides cingendus is a localised species that has only been recorded from the south and south west of the country, primarily from semi-natural coastal grasslands, but also from scrub and open woodland, where it is typically found beneath deadwood, large stones or mat-forming plants, within tussocks or amongst grass litter. It doesn't have many confirmed sightings, so is either considerably under-recorded or is actually quite scarce. In fact, according to both iRecord and the NBN Atlas database at the time of writing there's only been one confirmed sighting from Dorset in recent years. It is one of only a few woodlice species without a common name.

Updated, Sept.26 (v.2)