Bark Gnawing Beetle

This beetle is actually very interesting for a little black thing. It is somewhat flattened, has protruding mandibles with 2 teeth and clubbed antennae in which the 3 club segments are asymmetrical. It is 8 mm long and of the Family Trogossitidae. They are called the Bark Gnawing Beetles, but are actually mini-predators on and under bark. This one had a whole family of mites living on the underside (last 2 pictures). The larger darker ones seem to be the adults and there are dozens of nymphs of all sizes. The smallest ones are in a group under the proleg. Because all sizes are present, I would guess these live permanently on the beetle.