argus vs idas

[Paul]

Here are 4 different specimens from the Drome last June..... I have classed them all as argus, but wonder if there was a mixture of these and idas.... any opinions appreciated, tho' I know I can't communicate the jizz, and one doesn't have underside shot.... anyway... any thoughts??

No 1- got to be argus...




No 2.. uncertain..



No 3.. also uncertain..



and No 4 ...

[traplican]

I thing idas or argyrognomon. Here are my own photos of argyrognomon:



... and here is the common photo of P. argyrognomon with P. argus:

[Paul]

Interesting - thanks indeed...... Reverdin's is my absolute favorite, but I didn't see that in them - I was actually looking for the orange on the forewing undersides all the way through as your photos show beautifully... I did wonder when I was actually there... but my experience is VERY limited, just having seen them once or twice, somewhere else. So idas?????

[traplican]

I thing it is imposible to determine after photos. I have determined my butterflies as argyrognomon because it is more probable: According to the authorities argyrognomon is frequent on apropriate places near me while idas is rare here. But in mapping I allege it as Plebejus idas/argyrognomon.

[Padfield]

Hi Paul,

No. 2 is definite argus. The extent of the dark on the upperside hindwing rules out idas.

No. 3 is almost certainly argus. The dark extends at least as a dusting into s. 6.

No. 4 shows nothing definitive but would undoubtedly be argus if seen in Switzerland, both from the upperside and underside. I've never seen idas look anything like that.

No. 5 I don't like to call. I've seen that upperside jizz in both species but most commonly in argus.

The same goes for no. 6 - I have a preference for argus in both cases but cannot be certain. In Switzerland at least, idas has a clear blue s.6 on the upperside hindwing. Idas also rarely has the obscure inner edge to the dark forewing margin and is generally a neater insect. The problem is, both species are incredibly variable. We have at least two rather different subspecies in Switzerland alone.

Traplican, your argyrognomon are definitely that (at least, the underside views) and the argus in the last shot is also argus. Argyrognomon is the easiest of the lot to identify if a good underside view is had. Of course, pylaon can mess things up where present, because that's another very variable species (probably at least three species in Europe...). We're lucky in Switzerland that our subspecies/species trappi is easy, as Paul will remember from his last trip here.

Guy

[Padfield]

Here is a typical Swiss idas. Note how clear blue s.6 is, and how neat and narrow the forewing border is:



By contrast, this is argus:



For the record, this is argyrognomon:



Guy

[Paul]

Thanks..... I'll leave them filed as argus then... ....

[traplican]

Guy, I cannot help but on the last Paul's shot I see an orange color in the first patch of the first wing backside. Furthermore on the last three shots the black spots on the upperside of the back wings are distinctive and the black borders of the wings are thin.

I enclose shots of my Reverdins' habitat:


The place with mass occurence of Reverdin's is on this picture above the vineyard amid (to the right from the my neighbour's meadow where are lots of Weaver's, Nickerls' and Zygaena carniolica):

[Padfield]

Hi Traplican,

I'm not sure if you're suggesting Paul's last pictures are argyrognomon or that they're idas. They are very definitely not argyrognomon - no hesitation at all in my mind about that. The possibility of idas is to be taken seriously though and I don't rule it out. In Switzerland, if in doubt, I net the butterfly and examine the upperside hindwing, which seems to be definitive here.

I'm going to have a look at my own photos and see if I have any male argus with orange under the forewing. I have females like that, certainly. I must admit it had never occurred to me that males never did, but it would certainly be useful if true!!

Guy

[traplican]

I have consider soon idas regarding to similarity with some Matt Rowlings' pictures of one.

[Paul]

if it's any help... I have trawled through my SSB pics from UK where neither of the others (sadly) fly, most males do not have any underside forewing orange, where visible, but this one I think is definite, tho' could be argued a property of the way the light is shining through..



PS... lousy focus I know... pity 'cos could have been lovely

[Padfield]

Well, I certainly wouldn't want to lose any friends over this!! These two species are notoriously variable. As so often, they are usually easier in the field... I can accept idas for some of Paul's pictures, though I still feel strongly for argus with most of them.

Could that just be a tibial spine just visible in Paul's last picture... A close up of that leg might be definitive, if Paul has the original around.

Guy

[traplican]

Hmmm, I should really determine it as idas or argyrognomon ... Are they surely excluded in UK?

[Paul]

I really enjoy these discussions... really learn a lot from them.... which last picture Guy.... the last from my first set?? - I'll go enlarge the tibia, tho' that will really be fuzzy. (edit) Is that THE tibial spine they talk about ?? - Lanfrachis' diagram places it anteriorly, not posteriorly.


In any case - just want to show off my Reverdin's photos from 07...

[Padfield]

That last picture of Paul's is very definitely argus. Both the other species are excluded in the UK, but in any case it is class argus by markings. And again, it simply couldn't be argyrognomon from the underside. This is a really distinctive butterfly, that looks nothing like the other two from the underside - the books are naughty in suggesting it is difficult.

When I mentioned the tibial spine in 'Paul's last picture', I did, of course, mean the last picture in his first batch. It would be really good to have a blow-up of that leg, Paul.

Guy

EDIT - Posts crossed again! Classic argy shots, Paul. No one will dispute those!

[Paul]

aaaargh... crossed again Guy... tibial spine now ahead of argy photos... sorry!

and Traplican.... the points you raise are really those which put me in doubt before I posted.... so you're really being very helpful in making up my mind - thanks indeed

[Padfield]

I don't think that's the right spine, unfortunately - idas also has that one!!

This is guaranteed idas calliopsis from Switzerland. It was photographed on the breeding site, right next to the foodplant (sea buckthorn):



The relevant spine, which I'm not sure I've ever actually seen, is curved and points more forward. I think it will be a project for 2010 to get this sorted!!

Guy

[Padfield]

...and the relevant spine is only on the foreleg, not on the middle leg, if I understand correctly. I've never used this criterion (as you can tell) because it's hardly a field point, but I really want to get to the bottom of it now!!

Guy

[Paul]

well I've often looked on my photos of argus, but never seen it yet..... hmmmm

[Roger Gibbons]

I have looked in some detail at the so-called argus spine, and am still confused and unconvinced by what the books say. Rather than repeat myself here, this is a link to my argus page where my observations are given in some detail, together with some close-up shots of the spine.
http://www.butterfliesoffrance.com/html ... 0argus.htm

I am not 100% convinced that idas does not sometimes have a spine, too, prompted by some photos (e.g. 12968) that clearly appear to have a spine. Maybe 12968 is not idas, but that would be very surprising to me.
http://www.butterfliesoffrance.com/html ... 20idas.htm

I certainly concur that more study is needed here. I studied all my Plebejus photos a couple of months ago, but they were not entirely conclusive. I will try to get clearer photos of the legs next year.

For completeness, here is my argyrognomon page, very neatly marked specimens from eastern France showing the unf submarginal orange band extending to the apex. Another key identifier for argyrognomon is that the black chevrons are flatter (c.f. argus and idas) on the side adjacent to the orange.
http://www.butterfliesoffrance.com/html ... gnomon.htm

Roger