Origin of species !

[Paul]

Strikes me that although Escher's blue is well separate from the Plebejus group, it's underside might suggest it's closer related than thought, or is it just I don't know the taxonomy ? The Escher's below has a silver stud!



Clockwise from top left - argus, idas, escheri, pyaelon trappi.... any comments

[Padfield]

Cryptic reply from train, via iPhone: That's not escheri...

Doubtless you'll tell me I ID'd it in the first place!

More later,

Guy

[Roger Gibbons]

I came across this Provence Chalk-hill Blue (Lysandra hispana) a couple of years ago with quite copious silver in several of the marginal lunules. It is quite like the Chalk-hill Blue (L. coridon) in nearly all respects. I have never seen any Lysandra species anything like this before or since. Anyone seen a CHB with silver scales?
http://www.butterfliesoffrance.com/html ... _-_hispana

Just seen Guy's response. If not escheri then what? Some escheri are very distinctive and though this one isn't, I can't see what else it could be, although I am not familiar with pylaon so I would not know if it was or not, except that I understood pylaon has no silver scales (one of the key identifiers?). The marginal black marks do not look right for Chapman's Blue (Polyommatus thersites) and do look spot-on for escheri. I await further comments with interest.

Roger

[Padfield]

It's not impossible that the picture shows escheri (I agree, thersites is ruled out by the submarginal markings, despite it sitting on sainfoin), but what caught my eye especially, zooming in on my iPhone, was the evident cell spot. I think we've discussed before the possibility of a cell spot very occasionally in escheri but it must be the exception rather than the rule and so prima facie evidence against that species. I would have called it icarus. The half-chequering is not too much for that species.

To get back to Paul's original question, Roger's amazing PCHB illustrates how many of these superficial features, like silver spots, that we might associate with a particular genus, are not so deeply engrained in its identity as we might think! Many of them can appear sporadically in other genera. To my eye, the predominant characteristic of underside Plebejus is the lack of the white paint stroke in ss.4-5. Instead, the white surrounding the submarginal lunules forms an even band, or is more or less evenly moulded to the lunules. In Lysandra, Polyommatus, Aricia and other polyommatine groups the white paint stroke stands out a mile.

HOWEVER, when it comes to the origins of species, biochemistry trumps morphology every time (in terms of evidential value)!! The fact that all our European Maculinea, which are morphologically so similar, are now classed in two different branches of Phengaris, with alcon and arion widely separated from each other (more closely related to butterflies that look quite different than to each other) shows how misleading appearances can be (see: http://tolweb.org/Phengaris/112250). Morphology can converge well after species separate (or diverge very rapidly if one evolutionary branch continues in a different environment) and features can be repressed or remain hidden from the outside when the potential to make them is clearly there in the genes. Although in principle biochemistry could converge it is far less likely to than morphology, and none of it is hidden.

Those are my thoughts, anyway. Silver scales very interesting, but probably not indicative of a closer relationship than previously imagined.

Guy

[Roger Gibbons]

I would have expected to see more of the cell spot for icarus. To me, it does not have the feel of icarus. Those marginal black studs look very rounded, whereas I would expect them to be more elongated in icarus and touching the orange along more of the length. The sharp black chevrons in s4 and s5 are indicative of escheri, the brownish tinge to the orange unh markings, the unf marginal markings, to my mind all point to escheri. Not totally convincingly, I would agree. More balance of probabilities than beyond reasonable doubt.

Regarding the cell spot, I agree escheri does not have one. Neither does Turquoise Blue (Polyommatus dorylas). Ever? Try this one: http://www.butterfliesoffrance.com/html ... re_10Jul08_
You might not be surprised to learn that the man who spotted this lives near Lyon.

This is a good thread for exceptions!

On the question of origin of species, a good example of Guy’s explanation is Small Tortoiseshell (Aglais urticae) and Large Tortoiseshell (Nymphalis polychloros). They look very similar but polychloros is closely related to the Camberwell Beauty (Nymphalis antiopa), which it looks nothing like, and urticae is now grouped with the Peacock, recently re-classified as Aglais io, which is also looks nothing like.

[Paul]

Well.... I'm as certain as I ever have been it was escheri, given it was larger than icarus and theristes by 2x, although I know size can be difficult, here are the uppersides of the same chap...

[Padfield]

I wonder if Paul has an ups photo? Or, alternatively, whether he remembers identifying it as escheri for some reason other than that shot. I know I get very boring, but it is of course much easier to separate these two species in the field than from a single picture of the underside (I don't think I've ever even had to ask the question in the field).

If Paul has nothing more, I'd be happy to accept it might be escheri, for the reasons you give, Roger, though I would prefer not to call it at all, given the conflicting features. If it is escheri then it is an important shot, showing a cell spot. I don't think I have seen this before, though I have noted presences and absences where they shouldn't be in several other species.

Guy

[Padfield]

Our posts crossed, Paul!!

Guy

EDIT: And it only has a cell spot on one side, apparently!

[Paul]

if you look closely on the middle shot the faint tiny cell spot is there

[Mikhail]

Here's another escheri with a cell spot. La Pobla de Segur, pre-Pyrenees, July 1977.

Misha

[Paul]

That's a definite then Mikhail... I am encouraged this was worth posting given Guy's immediate reaction it should not be escheri.... therefore those 2-3 blue scales are odd.... and NOT photoshopped in btw.
I didn't truly think it might mean escheri should be put in the SSB group but it is an interesting thought...... must be convergence rather than surfacing of repressed genetic material.... yet I would have thought the latter more common. I suppose you could use the cell spot surfacing of repressed genetic material arguement to say it is related to icarus,
I would love to see the "family tree" of Blue butterfly species... anyone know where it can be seen??

[Padfield]

Try exploring around here:

http://tolweb.org/Polyommatus/124059

Yes, I was wrong to jump to conclusions based on that cell spot!! (I still can't see it on the other side - that white dot is in the wrong place). I live and learn!

Guy

[Paul]

Brilliant... thanks Guy, once more, fascinating!

Do you fancy a day looking for asteria in Switzerland one July day, I have the transport ( semi-serious )

[Padfield]

YES - deadly serious!!

It means heading too far east for me to do in a day trip, so I've never done it...

Guy

[Paul]

Excellent... really means 7th, 8th or 9th July, early start... how would puss be? I suppose many factors influence, weather etc, but I would really like to do it... we will talk nearer the time

[Lee Hurrell]

Am I alone in having seen plenty of CHB with silver scales, or are these within the normal boundaries of variation of a very variable species (apart from the other abberation in image 3)?

Here a just a few from last year. I've just realised they are all from Denbies in Surrey, so that may imply it's restricted to a particular colony?

Image 1 to 4 - 17th July 2010 and image 5 - 15th August 2010. They don't have quite the scaling shown in Roger's hispana, but it is there.

Cheers

Lee

[Padfield]

Well done, Lee!

I shall have to check all mine now! I don't think I've ever looked...

Guy

[Lee Hurrell]

Good luck Guy, mine took ages to go through!

Cheers

Lee