Aphthona nonstriata
I'm not quite sure if the leaf I found this on (in the photo below) was Yellow Iris (which it's typically found on) or Common Reed, but both were in the immediate vicinty.
female Aphthona nonstriata showing pronotum and spermatheca, Wendling Beck Environment Project (Norfolk, UK), 26th May 2023
This one was defintely on Yellow Flag Iris, at a different site within the same project area.
female Aphthona nonstriata showing frons, elytral humeri, pronotum, hind tarsal claw and spermatheca, Wendling Beck Environment Project (Norfolk, UK), 14th May 2022
This was also on Yellow Flag Iris, at the same place as the first. I've sometimes found it difficult to decide whether or not the tibial spur is placed at the middle of the lower apical margin or the outer edge of the apical margin, but I found that relatively easy to determine on this one looking at it ventrally.
female Aphthona nonstriata showing hind left tibia tip (and tarsus) from below and spermatheca (2 views), Wendling Beck Environment Project (Norfolk, UK), 17th April 2025