A universally accepted ID feature that is perhaps worthless?

I do still look at birds honestly but have not really had much to write about recently. And even though I have not been looking at butterflies this post will once again be about one - the same one - that has featured in my last two posts.

I did write that I hoped that I would be writing a further post on the skipper I photographed at Fornebu and here is that post although it is not how I hoped it would be.

As I said I would I have gone through pictures of Essex Skippers in the Norwegian and Swedish national reporting systems. I found none with orange antenna tips in the Norwegian database (which didn’t have very many pictures) but in the Swedish one it was quite easy. Unless they are misidentified Small Skippers which seems very unlikely then it is clear that THE feature which is stated in the literature as the way to separate the two species is far from as absolute as it is stated to be.

This was further confirmed today when I spoke with PK Slagsvold from the Oslo Natural History Museum who along with Reidar Voith had gone through the museums collection of Essex and Small Skippers. Their conclusion is that orange and black antenna tips can be found on both species and that only males can be safely identified using the shape of the black sex brand on the upper forewing. For females their conclusion is that there are no reliable consistent differences other than genitalia although this of course is not a field character. 

This doesn’t mean I didn’t unwittingly take a photo of Norway’s first Small Skipper but it seems extremely unlikely and as it is now clearly within the normal variation of Essex Skipper then that it was it is unless

proven otherwise which means a specimen and either Dna or genitalia check.

So we now have a few questions:

• how has the antenna tips colour become used as such an absolute character to separate the two species?
• where both species occur does this mean that there are lots of misidentifications especially of females.
• do we need publish an article to correct what appears to be a glaring mistake in the established literature?

Here are three Essex Skippers from Sweden this year showing orange antenna tips. After finding these so quickly I stopped searching for more:

This female is very similar to my one https://artportalen.se/image/6783618

A male I believe https://artportalen.se/image/6836646

And another female https://artportalen.se/image/6782465