I am grateful to Dr James Whitehead for allowing me to reproduce this image.
No interactions present.
In fact the antennae are NOT clubbed in Silpha atrata, although they are in some of the other species in this family.
There's a good key to this group in Beelte News, available to download from:
Look for Issue 3, October 2009.
Entomologist and biological recorder
Lat/Lng: 51.3901, -2.4033
OS grid ref: ST720657
Newbridge slopes Donkey Field.