This is a family with a good representation in the British fauna. Unfortunately many of the species are very similar to one another. In addition there does not appear to be any up to date key to the British species so this is an attempt to put this right. The first file below is a key to genus and contains keys to species of all the genera except for the big two - Atomaria and Cryptophagus. The second file is a key to the British species of genus Cryptophagus. A key to genus Atomaria is in preparation.
If you trial these keys please contact me with comments. I want them to be a useful resource for British entomologists. An error in the numbering of the second file was passed to be by Bruce Philip - many thanks. That has now been rectified.