My previous encounter with the family Rhysodidae was during a trip through California. This encounter of a series of 12 from Arkansas makes for another special experience for me.
Rhysodidae are one weird family. To me, they look just like a funky subcorticular carabid. Although they give off a colydiid vibe, this sort of convergence is seen in many subcorticular staphylinids, often obscuring subfamilial and intratribal relationships.
In this family, the entire body is covered in pilose sulci that escape my imagination for a feasible functional purpose. The mentum completely overshadows the mouthparts, and the mandibles are apparently functionless.
Adult characters clearly ally the rhysodids within the carabids, possibly near the scaratines, but larvae with their loss of maxilla and such further obscure actual relationship between rhysodids and carabids.
I get the impression that these beetles are not commonly picked up but can be locally abundant. They seem to like pine.