This is among my "marbled frit " images from Bourg St Maurice 1st week in July... now I wonder if it might be niobe, or even dk green... sadly I don't have an uns. shot...
This is definitely not Brenthis and can only be aglaja or niobe as you suggest - the weak sex brand rules out adippe, as well as the wing shape (and the curve of the submarginal spots). I strongly favour aglaja, for many little reasons, some of which I can put my finger on and some not - things like the delicacy (not) of the markings, the way the veins peter out on the forewing rather than continue neatly black all the way to the margin &c.
Guy
Last edited by Padfield on Wed Jan 30, 2008 11:57 am, edited 1 time in total.
I’m glad I’m not the only one who finds that niobe and aglaja can be confusing. The books usually group niobe and adippe together on the same page, but even though adippe can also be very lightly marked, they are easy to separate with a good sight of the forewing curvature, with aglaja on a different page and almost implying that niobe and aglaja are easy to tell apart.
In the far south of France niobe is common and always (in my experience) of the form eris and the males are very lightly marked so not too difficult to identify. I also find that the eris (and often niobe of the nominate form) hindwing round postdiscal spot in s4 is either absent or just a tiny pinprick, and I don’t think this is true for aglaja. If you can get to see it (sometimes they rest with hindwing fully extended), the spot in s6 is also visible and this is tiny in niobe but always (I think) strong for aglaja.
The main differentiator, but I do not know how indicative or reliable this is, is the solidity of the upturned V-shaped marginal marks, especially on the hindwing. In niobe, I generally find them to be quite thin Vs (sometimes more curved than pointed) but in aglaja they seem to be more solid and often almost triangular. Maybe this is an example of what Guy is saying about the delicacy of the markings, and certainly Paul’s forewing black markings are quite heavy and suggestive of aglaja.
Of course, one sight of the underside would render this discussion unnecessary…
fine images!... hope to seesome sometime.. I'm off to French Pyrenees in July.( Les Angles, - South East ).. but not the Val I think... hope something of interest shows up there for my trouble!!
The niobe eris underside is the most fantastic mix of beige and orange markings – here’s one from my local patch (in southern Var) with delicate black edging to the beige markings. The books tell you to look for the black spot within the unh small beige basal patch as being indicative of niobe, but I’ve never seen this in eris.
If you’re going to the eastern Pyrenees, the adippe form cleodoxa is quite common there and looks superficially similar to niobe eris, so you’d need to get a photo or get a good look.