Hedychrum niemelai

One of the spectacular jewel-like ruby-tailed wasps.

This beauty was found on top of a wooden post in the middle of a recently-cut meadow. I keyed it using Michael Archer's key. There were a few couplets where I wasn't sure about all characters but there was always at least one that was clear enough and none that were contrary. The only slight exception is that I considered the medial vein to be slightly curved which would point to genus Hedychridium, but the claw characteristics in this couplet were very clearly pointing to Hedychrum (I did check Hedychridium just in case and that didn't lead to a satisfactory conclusion). I found the apical-medial tubercles on the third sternite very difficult to see, being black on a black background - I was pretty sure but to make quite sure I needed to macerate the abdomen and isolate the third sternite from the fourth. The high quality photos of this in the Baldock and Hawkins paper describing Hedychrum nobile were also helpful in making sure I understood what these tubercles were meant to look like.

female Hedychrum niemelai showing forwing, edges of metapleuron and propodeum, hind claws, sternite 3 (in situ and isolated), Wendling Beck Environment Project (Norfolk, UK), 13th July 2023