Black-spot Buff Agonopterix propinquella

Formerly given the vernacular name Black-spot Flat-body.

I was pretty sure about this one's ID based on its external appearance. Some Agonopterix subpropinquella are similar but I don't think they ever combine the dark discal spots and the darker line bordering the paler area at the base of the forewings. To make 100% sure I checked the genitalia and indeed these appear to confirm the ID. The genitalia of the two species are fairly similar and as is so often the case, references tend to refer to diagrams rather than spelling out what the differences are. As I see it, the sacculus arms (cuiller) are straigher on subpropinquella, tending to curve gently inwards - but there is variation with some images showing a slight outward twist as well. The shape of the valvae appears to differ, being narrower and tapered more triangularly on subpropinquella, broader and more rounded on propinquella. I think there is also a slight difference in the shape of the juxta.

male Black-spot Buff Agonopterix propinquella showing genitalia, North Elmham (Norfolk, UK), 7th July 2023

I had only seen this species once before. The discal spot was much less distinct, though I suspected propinquella. However I was considerably less experienced then and it was before I had started gen detting, so I passed this specimen to Jon Clifton to confirm. He confirmed the ID, I think based on external characters rather than dissection.

Black-spot Buff Agonopterix propinquella, Bawdeswell (Norfolk, UK), 31st May 2012