Longitarsus flavicornis

This keyed straightforwardly to Longistarsus jacobaeae or flavicornis, with these two requiring gen det to confirm. The median lobe was clearly expanded and bulbous at the apex making it flavicornis. Duff only shows the median lobe in flat view but Hackston also shows it in side view and this shows an equally obvious (perhaps even more so) difference in the shape - much more gradually and finely tapered to a point in jacobaeae. This is supported by photos of the lobes at baza.biomap.pl.

male Longitarsus flavicornis showing close-ups of hind tibia, pronotum, elyra base and median lobe (3 views: flat, close-up of apex and side), Wendling Beck Environment Project (Norfolk, UK), 15th September 2023