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Saw these fritillaries at the Col de La Cayolle (2350m) in the southern Alps at the end of July. Any help working out which is which- or if they are all the same - would be much appreciated. The first 2 are photos of the same butterfly. The next 2 are photos of another butterfly. And then 2 different ones.

I find males of these two species difficult and rely on females to establish the presence or absence of a given species at a given site. Nevertheless, there are some pointers which hold good in a lot of cases.

Your second individual - pictures 3 and 4 - is classic pales. The discal spot in s.2 is straight and touches the cell, the underside markings are well defined, the wings are rather angular and the upperside forewing apex is heavily marked.

The first individual is atypical. I would tend towards napaea, but without any real confidence. The discal mark in s.2 floats off the cell but is not as linear or curved as you would usually expect, the wings are more rounded and the underside is more blurry (and generally less bright).

The third individual, in picture 5, is also atypical but I think it is napaea again. Although the spots are rather thick, they are the correct pattern for napaea and the wing shape is good.

The last one I'm really not sure about but on average I think it's pales - even though the discal spot in s.2 doesn't quite touch the cell.

Did you see any females, to confirm one or both of the species?

Guy

I suspect they are all pales, with varying degrees of confidence.
#1a/b I would say 95% pales
#2a/b 60% pales
#3 something of an aberration but the weight of the markings points toward pales
#4 90% pales.

The upperside measure I tend to rely on, apart from weight of markings, is the forewing post-discal series of spots, which are disjointed between s3 and s4 in pales and relatively straight in napaea. I feel they are all sufficiently disjointed to warrant an ID of pales, although #3 isn’t convincing and #2 leaves room for doubt.

The undersides of napaea at Cayolle are usually delicately coloured orange and beige with limited contrast. The shape of the markings on #2b slightly suggests napaea, especially discal s1 (narrow) and discal s7 (broadly regular rectangular).

If you saw them all AT the Col, I feel they are more likely to be pales. I have never seen napaea there, but it does occur on the lower reaches at around 2000m, and napaea from that location always seems to be very delicately marked. Conventional wisdom says that where pales and napaea fly together, pales usually flies at higher altitudes.

Interesting! I wouldn't put any of my percentages that high (so go with Roger! ), but strangely, the one I feel is most clearly pales is the second, which Roger expresses considerable uncertainty about.

Lafranchis points to the postdiscal spots Roger mentions as a way of separating these two but I've never seen it, and comparison of specimens across the range of the species shows it is a very variable feature in both species. That said, I've always suspected Lafranchis's criteria are geographically dependent and since he learnt the tricks of the trade in France it may well be that they work very well there.

As so often, some features are more obvious in the field - such as the size and wing shape - but I've found the position of the black spot in s.2 of the discal series to be very helpful (a criterion given in Bozano's Guide to the butterflies of the Palearctic Region).

I can easily give Roger the first individual, if he has seen pales looking like that. He agrees the second and last are most likely pales, so that's three out of the four pales. I would maintain dissent on the third, though. Despite my respect for Roger, if I were forced to wager a pint of Adnams (something that means a lot to me) I would put it on napaea.

The only way to be sure, apart from resorting to violence (genitalia, I mean), is to watch for females and their interactions with the males.



No mistaking that!

Guy

Thank you both for your very thorough and detailed replies. In answer to your questions, these were all photographed at the Col in very roughly the same area. We walked a little further down - to around the Refuge - and saw Cynthia's there but no other fritillaries like those above. To be honest, the weather was mixed to poor during our stay there, and the butterflies were not flying much. And no female fritillaries, I'm afraid. A good holiday though, with our target of 100 species reached - or was it 99?

I think #3 is so non-standard, I wouldn’t assert that it IS pales if there is evidence to the contrary. I’ve never seen one quite like that, so it is outside the range of my experience. The weight of markings suggested pales to me, but as it is an aberration, such pointers become meaningless. Also if it was AT the Col, that would be unusual in that I have been there many times (most recently the Greenwings tour in July) and only ever seen pales there. As a non-drinker, missing out on a pint of Adnams wouldn’t bother me unduly.

I wasn’t certain about #2b underside because the discal marks in s1 and s7 indicated napaea for the reasons I mentioned before. Compare these marks with #1b. These indicators seem generally reliable for the populations in the southern French Alpes. But other clues point toward pales.

In passing, I would add that the pales I see in the Valais (Switzerland) look quite different – here is a male seen this July (in a 20 minute spell of weak sun that was the only break in three days of low cloud, rain, and temperatures of 9C – the metéo was another two days of the same, so I gave up). As Guy says, females of pales/napaea are no problem. Curiously, I have been sent quite a few pales/napaea ID questions from the French Alpes, and it seems that 80% can be ID’d with confidence, some are probable and a few (like #3) just don’t fit.

I'd love to know where you photographed that last butterfly, Roger, as I would count it as almost certain napaea, not pales!! Please don't think I'm being contrary - I'm just trying to get my head round these species. By every criterion except the Lafranchis pd series thingy it is clear napaea - and if it's not napaea then the Bozano criterion (the discal spot in s.2) is completely useless. This is pales, photographed this year:



In Valais both species are very common and both fly at what you would normally call high altitudes - I've seen many napaea females at over 2400m. It would be nice to have a reliable criterion for the males, as these are usually more conspicuous - in my very few high trips this year (mostly in cloud) I've only seen males. Males are also more likely to wander vertically - maybe even to hilltop, though I've no direct evidence for this in either species.

Guy

It was near the Moiry dam. Here is a female that was flying in close proximity. I’m rather assuming the Bozano criterion (I’ve never encountered it before) must be that the pales s2 discal mark meets the intersection of the veins at the top end and napaea does not?

Roger

Roger Gibbons wrote:I’m rather assuming the Bozano criterion (I’ve never encountered it before) must be that the pales s2 discal mark meets the intersection of the veins at the top end and napaea does not?

That's one of several ups and uns criteria given there (which don't include the Lafranchis criterion - but if you find that works, Roger, I'll give it another try!). I quote:

Pales: upf the black spot of the discal row in space 2 touching (or almost so) the discoidal cell.
Napaea: upf the black spot of the discal row in space 2 usually separate from the cell.

I don't think there's any suggestion this is in any way conclusive on its own - it's just one of a number of cumulative indicators. There's no reason, of course, why there should be any conclusive criterion. The details of the markings are quite incidental to the taxon and variation within each species seems to me to be bigger than the statistical variation between the species, especially considered over their whole range.

Guy