The copper underwing problem

Firstly, I will put my hand up to having very little experience of these two species. Just a few caught last year and three so far this year. Last year I caught Copper Underwing Amphipyra pyramidea, once for certain, because I dissected it and then there were another two or three that either escaped or I let go. Once I've proven a species for a site I don't repeatedly take samples. I'm happy to agg. confusion species. At the time I was unaware of the palps feature, which has been given as a way of separating this species from Svennson's Copper Underwing Amphipyra berbera. 

On opening the traps yesterday I found two copper underwings within. Looking at the palps I appeared to have both species. Both moths were comparatively fresh, the A. berbera, especially so. 

Amphipyra berbera lower surface of hind wing. Note how the orange blends across the wing (or perhaps it doesn't enough...).

Svensson's Copper Underwing Amphipyra berbera - or not, this is actually A. pyramidea. Note the very dark palps with pale tips (which have no significance).

There was a bit of a discussion online about copper underwings and it appears that the palps feature is no longer considered good. This seems to be based on a 2022 paper in the Entomologist's Record and Journal of Variation. Whilst I think the overall conclusions of this paper are sound; don't entirely base your identification of either of these two species on one feature - "Many recorders refer to a single characteristic that can be viewed with ease such as the labial palpi or the contrast of the abdominal lateral chequered marking, without reference to any other or to genitalia." My own feeling is that there is a flaw in the argument within this paper because of the samples used for the analysis. Whilst very worn specimens were rejected from the analysis worn individuals were included see below.

 

  (Entomologist's Rec. J. Var. 134 2022). 

 Note with A. berbera the proportion of the sample that were classed as worn.

 What requires further investigation is if an animal that presents with black palps with white tips can it be anything other than A. berbera? (But the animal at the top is A. pyramidea). Surely, these would wear to paler, and thus it would be unwise to use the palps feature to identify A. pyramidea?

What is very useful in the paper is the list of features that are used to differentiate between the two species. What is not mentioned is how difficult some of these features are to use unless viewing from exactly 90 degrees. A number of these features, particular using dorsal views of the fore-wings, require estimation of angles and divergence of lines drawn across the wings. These analyses would have to be carried out from photographs and for them to be features that can be used reliably the photos would have to be taken using accurate management of the angles when they are taken. Whilst this is not impossible with live specimens I would suggest it can be tricky, both these species are quite lively. My photograph above is not suitable for these analyses.

The classic hindwing feature of how the coppery suffusion spreads across the ventral surface of the hindwing is hard to see unless the moth is killed (and even then it's not especially easy), they don't tend to spread their hindwings fully when in a transparent pot. I know some moth trappers are very skilled at managing live moths and seeing these tricky features, but in my experience this is difficult to do, and almost impossible to photograph unless an assistant is to hand.

I took the specimen of the moth above so the hind wing feature is easy to see. Additionally, the discal spot is more typical of A. berbera than A. pyramidea. It will be interesting to see what illumination the dissection brings, but I'm not expecting any surprises.

Here are my photos of the (presumed) Copper Underwing Amphipyra pyramidea. I didn't take the specimen as I have proven this species from the site previously.

 

Presumed Amphipyra pyramidea

What can be used to identify this moth? The palps are worn I would judge and whilst at a glance this would seem to be good for A.pyramidea a cautious approach would suggest not.

Only dorsal features of the fore-wing can be used as nothing else was photographed. Fortunately this photo would seem to be more useful for some analyses as it would appear to be close to a 90 degree view (and I do try to achieve this when I can having the camera set to give me this information when I'm taking the photos). The discal spot is perhaps more typical of A. pyramidea? Feature 10 in the paper does seem to be relatively easy to use  and helpful.

(Entomologist's Rec. J. Var. 134 2022). 

I think that this feature supports an identification as A.pyramidea for this moth. However, a word of caution, whilst A.pyramidea presents this feature consistently A. berbera can be variable so that it may on occasion show these proportions. A further feature referred to in the paper from Clancy 1997 suggests that the alignment of the peaks on the antemedial line and a continuation of that line to dissect (or closely so) the discal spot. Is also a useful feature. This can be seen in Plate 15 above. This criteria may work on the right-hand wing of my moth above, but it is not clear.

On balance I think this moth is Amphipyra pyrimidea.

Why is all this important? The paper gives a good summary of this, basically, the distribution of these two species in the UK is unclear because identification criteria are not used consistently by the various county moth recorders. Additionally, Amphipyra berbera was only recognised as a full species in 1968. In Scotland, whilst the initial colonisations appear to be clear (Leverton and Cubitt 2024), monitoring the future fortunes of these two species relies on consistent and accurate identifications.

 The Les Evans-Hill (2022) paper is available here - https://www.derbyshiremoths.org/wp-content/uploads/2024/08/Guide-to-Copper-Underwings-Les-Evans-Hill-Public.pdf?fbclid=IwY2xjawMigL9leHRuA2FlbQIxMABicmlkETFSWEhXT2VsVHNrMDM3UWJaAR4xv_nHXZS7q2gbrC8o2uYmYJ8HiDeIPzAD58zT0t2Yfxv8eHGJYUJgTVkDgg_aem_e2a-fB-yNYG9321vMVzt3w

A more general post will follow shortly.