Crepidodera plutus

The sharp contrast between the pale 1st to 4th antennal segments and the dark 5th to 11th segments is important to this species' identification. Compared to the Willow Flea Beetle Crepidodera aurata which I'm more familiar with it also seemed to have longer/narrwer elytra and the pronotum lacked the pink that is typically present on aurata. The photos suggest orangey sides to the elytra and pronotum but this is just the light - in fact the elytra, pronotum and head were uniformly shiny metallic green. This individual was found on oak, however this was presumably coincindental as the species is normally found on willow and sometimes poplar (both of which were present in the immediate vicinity).

Crepidodera plutus, Blackhall, North Elmham (Norfolk, UK), 11th September 2021

Both Duff and Hackston say only the 1st to 4th antennal segments should be pale but on the following beetle the base of the 5th was pale too. I think it must nevertheless be plutus as the border between the pale and dark is sharp, with no gradual darkening towards the tip. Just to make doubly sure I checked the spermatheca. That seems to help, although it isn't a perfect match to the diagram in Duff. The collum (the tubey bit extending out from the bottom and up the right side) is relatively broad and extends up to nearly the top of the nodulus and the position of the ramus near the top of this is also correct. The nodulus itself (the big bit in the middle) is broader than shown in Duff but is widest at the top with a bit of a bulge to the right, which is as shown in Duff. The cornu (the top bit) is longer than shown in Duff, and narrower at the base. Overall, of the five Crepidodera spermathecae illustrated in Duff, the one for plutus is the closest, despite some differences. Based on the various beetle spermathecae I've looked at so far it seems the exact shape varies between individual, so I don't think the slight differences from the diagram in Duff are anything to worry about.

This individual showed a distinct coppery tint at some angles, strongest on the pronotum (looks more pinky in the photos).

Crepidodera plutus, North Elmham Cathedral Meadows (Norfolk, UK), 20th May 2021