In 2005 I published in British Wildlife (Jones 2005) an identification guide to the land flatworms (terrestrial planarians) then known in Britain and Ireland. More species have since been recorded and this article details these, updates information on the previously known ones and corrects some errors.
Able to hide in the smallest of spaces, there are few more successful stowaways than flatworms and alien species routinely reach Britain with imported plants and soil; Hugh D. Jones provides a rollcall of the species recorded to date with tips on identification.