Brown Argus

[NickMorgan]

I've been enjoying Guy & Co's wonderful new Butterflies of Europe app. One thing I have learnt, that I didn't previously know was of the existence of the Southern Brown Argus, Arica cramera. These don't appear in any of my books.
I am keen to learn more. Is this a recent discovery? What are the identifying features? I see that they boundary between the Brown Argus/NBA/SBA are quite neat with little overlap. How sure are we that they each occupy these areas?
If anyone can point me towards some more information I would be very grateful.

[David M]

Me too. I've never previously heard of it.

[Padfield]

I'm delighted you're enjoying the app, Nick!

Aricia cramera was described in 1821 but most books treated it as a subspecies of agestis until relatively recently. It completely replaces agestis in Spain, the Canaries and Sardinia (our app has agestis in Sardinia, but the latest information I have suggests we need to correct that!).

It is more brightly marked than agestis, usually having complete and conspicuous lunules on the upperside forewings and also being strongly marked on the underside:


(Spain)

I only have an old picture from La Palma to illustrate the ups, but you have great pictures from Pete and Matt on the app, Nick. Here's mine from La Palma:



You can see how well developed the orange lunules are.

The other common Aricia species in Spain is montensis - though there is some dispute as to whether the Pyrenean populations are montensis or artaxerxes allous. My (fantastic!) new Spanish book (Muñoz Sariot, Biología y ecología de los licénidos españoles) calls the Pyrenean populations montensis, while Tshikolovets opts for allous.

This is montensis:



The group is very difficult, taxonomically, and changes are likely to be made to the present nomenclature. The Swiss recorder told me the situation in Switzerland is very unclear.

Guy

[Padfield]

Further: Muñoz Sariot (Biología &c.) says that the present arguments for distinguishing agestis and cramera at the specific level are based on small differences in the genitalia and that genetic studies are needed to prove the case. He notes that variation within both species mean there are individuals that cannot be ascribed from wing differences alone and concludes that the arguments of those who still regard them as subspecies must be taken seriously.

Guy

[Roger Gibbons]

Southern Brown Argus (Aricia cramera) is given as a species in its own right (c.f. A. agesits) in Higgins and Riley (published 1970) but Lafranchis refers to it as a "subspecies, sometimes considered a distinct species". However, the new European taxonomy lists it as a separate species.

Regarding Mountain Argus (A. artaxerxes), Higgins and Riley describes the three subspecies as artaxerxes (nominate form found only in the UK), allous and montensis. Lafranchis says the taxonomic relationships between the three are unclear. In the European taxonomy, montensis is listed as a separate species (Southern Mountain Argus). The other species listed is artaxerxes (Northern Brown Argus). Presumably allous is considered as a subspecies of the nominate form artaxerxes and there is no species described specifically as Mountain Argus.

There are some comments on the differences between the three artaxerxes subspecies on this page, although I am by no means confident that which are allous and which are montensis. http://www.butterfliesoffrance.com/html ... xerxes.htm

[Padfield]

It's a strangely confused situation, isn't it, Roger? Although allous is apparently universally regarded as a subspecies of artaxerxes, and montensis is now very often described as a different species, there is no agreement on which populations belong to which taxon in the south of France and the Pyrenees. The map in Tshikolovets includes all French populations as allous, as well as all populations in the entire band of the Pyrenees and west to NW Spain. For him, montensis is exclusively a species of the Iberian Peninsula, south of the Pyrenees. Muñoz Sariot, on the other hand, considers all the Spanish populations, including those in the Pyrenees, to be montensis - he doesn't include artaxerxes (allous or otherwise) in his book except to mention the controversy and say that biological and ecological considerations support the ascription of specific status to montensis. Kudrna includes just one map for all three taxa artaxerxes, allous and montensis.

I'm provisionally going with Muñoz Sariot, as he's a Spanish specialist and produced his work most recently. Unfortunately, though, he has nothing to say about the southern French populations.

Guy

[NickMorgan]

Wow, it just goes to show how much more we have to learn. So, it seems that I have only seen Southern Brown Argus and Northern Brown Argus, but no Brown Argus!

Southern Brown Argus, Algarve

Southern Brown Argus, Jalon Valley, Spain

Southern Brown Argus, Menorca

Northern Brown Argus, Scottish Borders

[David M]

Wow, it just goes to show how much more we have to learn. So, it seems that I have only seen Southern Brown Argus and Northern Brown Argus, but no Brown Argus!

Thanks for the comparative shots, Nick.

Does Northern Brown Argus always have 'blind' spots on the underside of the forewings?

[Padfield]

Yes - nice shots, Nick.

Does Northern Brown Argus always have 'blind' spots on the underside of the forewings?

No - only the Scottish subspecies is like that. In England and on the continent the underside is much more like that of agestis. Here is one from near me in Switzerland, photographed in May 2011:



Guy

[David M]

Thanks, Guy. Reliable as ever.

I'm tempted to ask why the Scottish NBA has blind spots whereas the other variants do not, but I suspect that'd be beyond even the remit of Jeremy Thomas?

[marmari]

I have found this subject very interesting and looking into my guides it seems that the Southern BA does not occur in Greece.
Therefore the attached photos taken there must either be the Northern or agestis.I do not know which, but I am sure that one of you will solve that for me.

brown Argus Greece.JPG

Brown Argus greece 2.JPG

[Padfield]

At what altitude did you photograph this butterfly, marmari?

Guy

[marmari]

200-250 metres.

[Padfield]

I would tentatively say brown argus, from the rather rounded apex and the low altitude. Typically, in southern Europe, artaxerxes is found at higher altitudes.

Guy