When Cleuson scooped out the rich organic material from inside the mucajá palm pictured in my last post, this beetle, perhaps a darkling beetle, came with it. I'm sorry that I didn't take time to get more pictures because I don't have a good view of the head. My digital camera, bless it, is so slow, the beetle had partially disappeared under the mulching material before it recorded the image. I suspect that these beetles play an important role in decomposing fallen trees. Thank you, we needed that fertilizer.
Later annotation from Ted MacRae: Beetle yes, darkling beetle no. This is a bess beetle (some people call them bessbugs or bessiebugs) - members of the scarab superfamily. Bess beetles are semi-social - rare among beetles - and colonize decaying logs. Adults and larvae both produce sqeaking noises when disturbed, but more likely this evolved for communication with each other. Adults actually feed the young - preparing decayed wood with salivary secretions beforehand. Very interesting beetles! Thanks, Ted. I copied your comment because I know that not everyone reads comments ... and this information is important.