Range & Status

The distribution of this species in the National Atlas (Kerney, 1999) would imply this is a nationally scarce species in Britain. However, subsequent surveys, especially in Dorset rivers, have resulted in many new records so the species would no longer warrant this status. In Cornwall the only records are from the Bude Canal (SS20C) and from the Tamar Lake Reservoir (SS21V). Both records date from 1973 and the species has not been refound, so its current status in Cornwall is unclear.