Chaetocnema concinna

Found on Common Nettle this little beetle had a damaged left elytron. I didn't immediately recognise it as a Chaetocnema as it's a very different beast to the only member of the genus that I was familiar with (hortensis) but the outer tooth on the mid and hind tibia pointed me to the genus. Getting it to concinna/picipes was straightforward but eliminating picipes took a little more effort. The shape of the 11th antennal segment seemed to be almost as pointed as shown in Duff for picipes but it was slighly asymmetrical which pointed to concinna. Antennomeres 2-4 were clearly pale dorsally which is not normally the case for picipes but the way this is worded suggests it's not diagnostic. The spermatheca is not quite as bulbous-bottomed as Duff shows for concinna, but clearly broader in the bottom half than the top half unlike picipes which is shown as being barely any wider at the bottom half than the top half. Not a totally straightforward identification but all characters pointed, if not as clearly as I would have liked, to the commoner species so I think it's safe to name it as such.

female Chaetocnema concinna showing its hind tibial tooth, head (from front to show median keel and from above to show punctures around eye), antennal tips (two angles), antenna base and spermatheca, Wendling Beck Environment Project (Norfolk, UK), 29th April 2023