www.ukbutterflies.co.uk

Took this at Gait Barrows this afternoon. I thought it was a Pearl Boardered Fritillary. Now based on the size I wonder if it's a Small Pearl Boardered Fritillary.

It is a Pearl Bordered Fritillary.
The heavy markings are the difference between the P B F and the Small P B F which has a lesser/lighter markings.
Nice picture!

Thanks Andrew, that a good tip.

I'm sure this is a pearl bordered, not least because it is still a little early for SPB to be on the wing. Is there anything other than the relative lightness/heavyness of the markings that gives the game away in an open wing shot such as this? I ask because there will inevitably be some variation in the markings between individuals of the same species. I've been carefully studying shots on the species pages and must admit I would be hard pressed to give a definitive answer at a time when both butterflies are on the wing.

To my eyes, apart from the variation in the lines and other darker markings, the Pearl Bordered has a richer ground colour than the SPBF. The latter's ground colour even when fresh has a faded appearance in comparison.

In a 'usual' spring and Summer, it's often late June or even early July before the SPBF appears in Gloucestershire. It occurs on the higher ground of the Cotswolds but is less frequent there than the stronger colonies in lower level Woods in the Vale of Gloucester.

Thanks Cotswold. I still feel that heavyness/lightness of markings and the relative richness of ground colour is a little vague given that there will inevitably be variation between individuals of the same species. I was wondering if there is a mark of some sort, visible in an open wing shot, that is present on one species but not the other? I've studied photos on the species pages and have to say I would struggle to give a positive identification, based on an open wing shot, if I was not presented with additional information such as location, flight time etc. And as we know, location and flight time can overlap.

A useful tip, especially in males, is that in pearl-bordered the submarginal loops are little floaty triangles that usually appear not to be attached to the marginal lines. In small pearl-bordered these marks form arches contacting the marginal lines and not infrequently enclosing a slightly different ground colour too.

Guy

I've had a look at the pictures on this site and the floaty triangle versus arches works for all of them.

There is another feature I learned from Tim Cowles (his site is http://perso.orange.fr/felixthecatalog.tim/, though I don't think he mentions it on the site). Look in space 2 on the forewing. There is a spot next to the cell, then another one out along the space, then the marginal markings. In pearl-bordered fritillary that central mark is roughly midway between the inner mark and the edge of the wing. In small pearl-bordered it is considerably closer to the edge of the wing than it is to the inner mark.

This feature works with insects in almost any state of disrepair, providing you can see the upperside pattern.

Guy

Thanks Guy. I've checked the species pages again and the floaty triangles/arches differentiation does seem to hold true, though to my eyes one shot in particular (Wayne Clinch's Bently Wood PBF) is borderline.

As regards the markings on the second wing cell, would it be possible to mark and upload a photo so I can see exactly what you mean?

I shall do just that tonight!

Guy

The top picture is a small pearl-bordered fritillary I photographed years ago in Norway and the second is pearl bordered, photographed this year in Switzerland.



I must repeat that I got the spot ratio thingy from Tim Cowles, who is a bit of a genius for noticing things like that!

G

Hmm. I would not always trust the floatines of those triangles, nor the paler color. However, the shape (triangle vs. arc) seems to be generally true here as well. See this page.

On the other hand, the spot spacing is marvellous!

Thats pritty good Guy!

Small PBF:

Several white spots in yellowish discal band on hindwing upperside

PBF:

Yellow discal band of hindwing underside enclosing only the shining silver white spot in the middle.

What a super site, JKT!! I'd like to link to it from my own. Is this the right start page?

http://www.jkt.1g.fi/Butterflies/Butterflies.htm

And yes, the floaty triangles are not infallible, and frequently not really floaty, especially in females; but somehow when you get the jizz of them (and the rest of the markings) they do seem to work.

Guy

PS - I'll link to yours, too, Dave, when your main page links up to the rest of it. When I've visited recently I've not got past the first page. May be me.

sorry Guy. I will say when its done.

Thanks for posting the photos Guy, that has cleared up the confusion.

padfield wrote:What a super site, JKT!! I'd like to link to it from my own.

By all means! Yours has been in my personal bookmarks for quite some time.

padfield wrote:Is this the right start page?

http://www.jkt.1g.fi/Butterflies/Butterflies.htm

It is for butterflies, which is the main thing.