Atheta hypnorum

This came to light and was the second beetle I identified using Duff's new volume 2, and like the first I didn't find it straightforward. Having been unable to key it successfully I checked the genitalia and matched the spermatheca against all the diagrams in Duff. Atheta hypnorum was an excellent match and nothing else was anywhere near as close. Working backwards through the key from hypnorum I found one couplet where it didn't convincingly key correctly. On the first antenna I checked the 11th segment was the same length as the 9th and 10th together whereas it's supposed to be clearly longer in hypnorum. On the other antenna it was longer, by around 10%, but this still wasn't convincing. Despite this apparent discrepancy (and the fact that there don't seem to be many records of this species in Norfolk), the spermatheca is so distinctive I think the ID must be right (though as always happy to be corrected).

female Atheta hypnorum showing head from above, front and side, pronotum (2 views), elytra, mid tibia, maxillary palp, tergites (2 views), sternites, apical sternites, antennae tips (both) and spermatheca, Wendling Beck Environment Project (Norfolk, UK), 18th August 2024