Light Orange Underwing Archiearis notha

Formerly placed in the genus Boudinotiana. Only known to occur at one site in Norfolk. I don't think there's any great secrecy about this site any more but I won't reveal the name of the site here.

This very tatty specimen was found when looking specifically for Light Orange Underwing. After an initial flight view it rested on a sapling in the woodland ride where we had been searching. In order to check the identification the moth was captured temporarily, but it turned out to be difficult to confirm. The wings were very worn and the critical part of the hindwing was completely missing. It was a female so the differences in male antennae were not useful. After careful examination of multiple photos of UK examples of both Light Orange Underwing and Orange Underwing Archiearis parthenias I thought I could find other differences in the wing pattern between the two species, and that seemed to confirm it was Light Orange Underwing. However the German website Lepiforum had several images that did not support these differences, so I was not completely convinced.

We considered retaining the specimen in order to check the genitalia, but I was reluctant to do so as this is a Nationally Scarce species at its only Norfolk site. On the other hand it was clearly near the end of its life, and in a wider context its conservation status is Least Concern. We took multiple in-pot photos hoping that we would be able to resolve the ID subsequently, without retaining the specimen. It was meant to be released shortly afterwards, but the member of our party responsible for doing so discovered that it had died while still potted up (confirming our suspicion that it was near the end of its life). The specimen was later passed back to me and my subsequent examination confirmed that it was not gravid so, assuming it had mated successfully during its life, it had already laid its eggs. I therefore don't feel too bad about it having not been releaesd before its demise, although that had not been my intention.

The genitalia resemble photos of female Light Orange Underwing genitalia at the Moth Dissection website. Unfortunately this website does not currently have any photos of female Orange Underwing genitalia, and I can't find any photos elsewhere, so I am unable to categorically state that this definitely rules out Orange Underwing. However, the male genitalia are very obviously different between the two species (perhaps this is why the two species were formerly considered to be in different genera?). Given that the male genitalia need to link together with the female genitalia it seems unlikely that there would not also be fairly obvious differences between the female genitalia. So my working assumption is that this is indeed a female Light Orange Underwing, though if anyone can point me to what female Orange Underwing gentilia look like I would be grateful.

female Light Orange Underwing Archiearis notha showing field views (2 photos), in-pot views (5 photos) and dissected wings after death (from above and below) and genitalia, mid Norfolk (Norfolk, UK), 13th April 2024