Gloucestershire Naturalists' Society

Isopod Report 2001 by David Scott-Langley

The Gloucestershire woodlice seem to produce more records than any other group for which I am county recorder. There were 195 records representing sixteen species, not as many as last year on either count. There were no new county records but several county rarities put in an appearance. The "Famous five" (Armadillidium vulgare (Pill woodlouse), Oniscus asellus, Porcellio scaber, Philoscia muscorum and Trichoniscus pusillus) are usually to be found at most sites, represented by some, if not all, of these species.

Armadillidium depressum. This close relative of the common Pill woodlouse, has a southwesterly distribution with Gloucestershire being on the edge of its range. It only rolls into a ball if absolutely necessary, preferring to cling to the surface on which it is found, as it is unable to tuck all its antennae and legs completely away. Found at eleven more sites during the year, it is certainly widespread in the county. The best place to see it is on the roadside wall of the Bisley Road Cemetery, Stroud, where it can be found in good numbers mixing with the next species.

Armadillidium nasatum. Similar to the above but with greyish markings on the body. Apart from Bisley Road, this species was also found at two other sites, both in Cheltenham. Although widespread, if sparsely recorded, over the southern half of England, its stronghold appears to be round the Severn estuary/Bristol Channel area so it ought to be more widely recorded in the county than it is at present.

Haplophthalmus mengei. This species has been quite elusive in the past, with only two records for the county (one being my garden!). However, in 2001 four new sites were found (by chance including my sister's garden in Cheltenham!) Being small, white and living in the surface layers of the soil, this species will probably continue to go unnoticed.

Ligia oceanica. Following on from my report last year, Roy Bircher e-mailed me to say that he has seen this, the Sea Slater, retreating up the beach ahead of the incoming tide at the old Frampton breakwater on the River Severn. This places it in the l0krn square that is furthest upstream from which the species has been recorded, and that record was pre 1970.

Porcellio dilatatus. This is only the 3rd county record for this species. One specimen was found in a pitfall trap during a FWAG survey by R. Wilder, near Bromsberrow in the northwest of the county. Usually associated with dairy farms and cattlesheds in particular, this one was caught on the edge of a field.

Trachelipus rathkei. Although no new sites were added to the county list for this recently-added species, I did find it at Upton-on-Severn over the border in Worcestershire (believed to be the first county record there) thus continuing the species association with the Severn flood plain. I would not be surprised if this species appeared in the Lechlade area of the Thames as it has been recorded just over the border in Oxfordshire.

My thanks go to members of the Gloucestershire Invertebrate Group who passed on specimens during the year.

Copyright © Gloucestershire Naturalists' Society:  2010. All rights reserved.

If you have any comments on or experience any problems with this page please contact R.Homan (robert.theapiary at gmail.com) (You will need to edit the word at)