The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.
Range & Status
A rare and very localised species recorded from Cornwall, Devon, Dorset, Wiltshire and the New Forest. A national distribution map is provided by Foster (1983).
First recorded from The Lizard in 1919 by J.H. Keys; subsequent records are from Gwithian in 1938 by R.T. Bannister and again in 1981 by A.P. Foster, and Porthtowan in 1962 (Eve, 1963). Attempts to locate the species at these sites have failed in recent years, and it is now apparently restricted to a stream near Portreath, where it is uncommon and highly localised.
Habitat & Ecology
Inhabits small stony and gravelly streams, some of which may dry out.
Habitat loss; pollution of watercourses by point and diffuse sources; scrub encroachment of small watercourses.
This species is listed on the UK BAP Priority species list (2007) and was listed (middle list) as a globally threatened/declining species (BSGR, 1995).
I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.
The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.