A large leech that may be over 80 mm contracted when mature, and up to 200 mm extended. Whilst immature leeches are orangey-red they turn dark grey-green at maturity.

It inhabits fresh water, even where there is sewage contamination, although the adults will also forage on land in moist soil. In water they attach themselves under stones, particularly at the edges of the stream.

Adults are amphibious, leaving the water to forage on land for earthworms. Immature specimens do not appear to leave the water.

The few records available all come from the southern half of Britain.

Common in Leicestershire and Rutland.