Two species in Britain, Pediacus depressus (Herbst) and P. dermestoides (Fabricius).  Both are small (3.5-4.5mm) red-brown beetles, dorso-ventrally flattened as an adaptation to life beneath bark on a range of trees in various states of decay.  Pediacus dermestoides is widespread across southern England while P. depressus is a rare species with only a scattering of recent records.