Megasternum concinnum

This was in a pitfall trap (in propylene glycol, so no live photos). It keyed to this species fairly straightforwardly, though at first I was a little concerned as it appeared to have a contrastingly pale pronotum whereas I couldn't find any photos or description that allowed for this. There was some varation, and on some individuals in photos it looked browner than in others, but not much browner than the elytra. I was, however, examining it in liquid and when it had dried off a bit, the contrast disappeared - it wasn't much paler than the elytra after all.

Duff only includes one species in this genus although he does mention that a second species is "awaiting formal notice" (but doesn't provide any clue as to how to identify this). The UK Beetles website recognises both this species and Megasternum immaculatum amd provides some steer as to how to tell them apart. Mine appears to be a female so I can't use the male genitalia character, but I think immaculatum would be blacker and have darker antennal clubs.

Note that in propylene glycol the head, pronotum and abdomen have become partially separated - in life (and again in death after it had dried out a but - see last photo) this would not have been so. When it dried out (last photo) it pulled itself together again. Once contracted its length was about 1.9mm.

Megasternum concinnum, Wendling Beck Environment Project (Norfolk, UK), 29th to 31st March 2024