Tenthredo brevicornis

I have really struggled to identify some of the yellow and black Tenthredo species - they frequently seem to show characters that aren't fully consistent with the available keys and I've had to leave a few unidentified. Even so - it seems that I have still allowed some errors to slip through - I have recently realised that some of those I have previously identified as arcuata were in fact brevicornis.

While identifying a recent arcuata I compared the saw with my photos of the saw of this one that I had identified as arcuata and they are clearly different. In fact this one appears to be spot on for brevicornis and the black scape would also support that ID. There is a black stripe along the fore femur but this is narrow and is not visible at all in the photo taken from directly above. For some reason I had badly edited the photo of the saw which made it harder to see the detail - I have now replaced the photo with a clearer version.

Tenthredo brevicornis showing saw, North Elmham Cathedral Meadows (Norfolk, UK), 1st June 2020

This one also has a black scape and the black line on the fore femur is narrow and is not visible in the photo taken from above. Although originally identified as arcuata I now think this must have been another brevicornis.

female Tenthredo brevicornis, North Elmham Cathedral Meadows (Norfolk, UK), 6th June 2018

I'm less sure about this one. This photo is all I've got to go on now but it appears to show a black scape. The black on the fore femur seems to be a bit broader than the ones above that I now think are brevicornis, but I suspect this one may be too. I'm not completely convinced though, so perhaps it would be better treated as unidentified?

possible Tenthredo brevicornis, North Elmham Cathedral Meadows (Norfolk, UK), 18th June 2018

This is another tricky one to sort out without a specimen. The scape is covered in pollen making it look partly yellow but I don't think it is. The black line on the fore tibia doesn't look as broad as it does on some arcuata but it does seem to be visible from above which wasn't the case on the ones that I more confident about reidentifying as brevicornis. Unless anyone else knows better I'm inclined to treat this one as unidentified too.

possible Tenthredo brevicornis, North Elmham Cathedral Meadows (Norfolk, UK), 25th May 2018