Common Green Sawfly Tenthredo mesomela

This individual was found on Mullein, but that isn't listed among its various larval foodplants.

Common Green Sawfly Tenthredo mesomela, North Elmham Cathedral Meadows (Norfolk, UK), 29th May 2019

This one was potted off an Oak leaf. I had some difficulty identifying it. It clearly looked like this species (and ObsIdentify was 100% sure it was, for what that's worth), but I like to make sure by keying it and there I encountered some challenges. Firstly with the genus key, the hind femora didn't extend beyond the abdomen and the labrum was flat (both pointing to Tenthredo), but the hind femur was about the same length as the hind tibia (which was meant to be wrong for Tenthredo). Then it seems the main confusion species for mesomela is Tenthredo mioceras (an upland species which I don't think is likely in Norfolk) and I struggled to make sense of some of the differences. Firstly I couldn't see any difference in the texture of the top and bottom of the mesopleura (supposedly coriaceous above and shining below). Secondly mesomela is supposed to have fuscous hairs on the head whereas mioceras has silvery hairs on the head. On this the hairs on the top of the head, indeed pretty much everywhere that was black, were black (fuscous maybe I suppose) and the hairs on the green bits of the head were silvery. I also wasn't sure if the shape of the labrum was quite right. So I thought I'd settle it by checking the penis valve, but that confused matters even more. The side view diagram in the RES key matched up (with mesomela) pretty well, but the view from above didn't. Lacourt doesn't show the penis valve for mesomela but his diagram of the penis valve for mioceras looks completely different to the diagrams in the RES key. So all a bit confusing, but all things considered I think it must be mesomela.

Common Green Sawfly Tenthredo mesomela showing forewing, hind femur and tibia, basal antennal segments, head from in front, hairs on lower/rear head, hairs on top of head, labrum, abdomen tip and penis valve (flat and from side), North Elmham Cathedral Meadows (Norfolk, UK), 24th May 2024