Proctotrupes brachypterus

Both of my "comprehensive" insect guides seem to exclude the entire superfamily Proctotrupoidea so it's little wonder I had no idea what this was at first. Various keys covering what I thought were all the likely groups of Hymenoptera failed to lead me anywhere sensible and even Mike Hackston's keys, which eventually came good, caused me some difficulties at first. The forewing contains some obvious dark veins and some much fainter lines which I presume are also veins, albeit much less conspicuous; including these fainter veins there seemed to be more than 2 closed cells. Thus at Hackston's key to parasitic Hymenoptera superfamilies couplet 7 I struggled. Faced with an insect that I thought had more than 2 closed cells and was definitely more than 5mm long, I ended up at Chrysidoidea, although it seemed to be stretching it to say the hindwing had a jugal lobe. The members of Chrysidoidea that I've come across look nothing like my insect and with at least one reference describing the whole superfamily as ruby-tailed wasps, I eventually concluded that this could not be right. Eventually I worked out that my insect looked rather like some members of Proctotrupoidea, and if I were to go the other way at couplet 5 this is where I got to.

Thankfully Mike's keys to Proctotrupoidea were much more straightforward and I sailed through these relatively simply to reach Proctotrupes brachypterus. I've no idea what their status is (NBN only has 2 UK records) but I see from Twitter that Andy Musgrove has recorded the species in Norfolk before. My niggling doubts over the apparently wrong number of closed cells was laid to rest when I searched for photos of Proctotrupes online and found that they had similar venation. The length of the insect (from front of the head to tip of the wings) was 8.7mm (comparing nicely with Andy's example which he said was 8.5mm).

male Proctotrupes brachypterus showing wings, side of thorax, close-up of metapleuron and tibial claws (both hind legs), Wendling Beck Environment Project (Norfolk, UK), 12th October 2022

This second individual was with the one above, and clearly a female with a long ovipositor. The ID was complicated by the fact that the specimen had started to go mouldy when I examined it. I initially assumed it to be a different species in view of its rather different appearance (a little smaller and much darker - the abdomen looked black at a glance although it was in fact dark reddish). The nervulus was much closer to the basal vein which seems to point to genus Codrus (and the angle of the radius would make it Cordus niger) but other characters were wrong for this. I could barely make out any eye hairs - they certainly weren't as long as indicated for niger, and the other genus characters didn't seem to be present (the hind tibial spurs were too short and there was no rounded bulge on the frons to speak of). So, assuming I didn't go wrong earlier in the keys (I double-checked and couldn't see that I did) I think I'm safe to rule out Codrus despite the nervulus position - and in that case it keys to Proctotrupes.

Determining which Proctotrupes wasn't as easy as the male, as the top of the metapleuron wasn't noticeably smoother except towards the top corner, which would be ok for gravidator. The shape of the radial vein wasn't quite such a good match for the photo of brachypterus in Mike Hackston's key but I think it fits the description of brachypterus best, while the clearly curved spurs on the mid and hind tibia, the fully-hairy pronotum sides and the grooves on the ovipositor sheath all point to brachypterus rather than gravidator. Throw in the fact that it was with a male brachypterus and all things considered I think the ID must be ok, but of course I'm always happy to receive feedback from anyone who knows better.

female Proctotrupes brachypterus showing wings, Wendling Beck Environment Project (Norfolk, UK), 12th October 2022