Azure or Variable Damselfly

[MPC]

This issue was raised recently, but my images have been bugging me for some time. Is it a female Azure (blue form) or female Variable? The Pronotum can be seen edge-on and shows a change of form in the centre and then resumes a straight edge. Is this typical of Azure or Variable. The field guides show the Pronotum from above, but is it possible to separate the two species with the view I am showing?

I am aware that there is no bar between the post-ocular spots, but that does not appear to be diagnostic feature anyway.

Any help will be appreciated.

MPC.

[Jason Green]

Morning MPC,

Variable Damselfly I believe.

Take care,

Jason

[GuyF]

Hi MPC, welcome to wab!
I think this is quite a tricky one, I've only seen Variable Damselflies once though, earlier this year in Somerset. When you get a good view the shape of the pronotum is very distinctive, here's one of the female Variables that I saw

However, the lobe in your picture could possibly be misleading, here is a cropped photo of a female Azure Damselfly, the pronotum is almost flat but there is a pale patch underneath which, from a distance, could appear to be a lobe.


Whereabouts was your photo taken? That could possibly narrow it down a bit, although not if both species occur at the site!
Guy

[MPC]

Thanks for your reply Guy. My images were taken in Worcestershire which is yet to record Variable Damselfly.

My interest in the images came about because of the form the edge of the Pronotum takes ie the edge appears to double-back on its self before resuming a straight line. I think that only a similar image taken from the same view point for both species would provide a true comparison.

Thanks again.


MPC

[RoyW]

Hi MPC,

Your photo looks like a blue form female Azure to me. As you know, the angle of the shot is not the best one for typical shape comparisons of the pronotum, but even from this angle I would expect to see a more obviously indented shape on Azure (& it would be quite likely for the pale rear border of the pronotum to be clearly broken at the indentations).
The lack of a bar between the post occular spots might not completely eliminate Variable, but it is generally a good pointer towards Azure.

Unfortunately the females of these two species are not always easy to tell apart - and the features visible in your photo are (IMO) certainly not good enough to identify this as a Variable (especially a first county record).

Roy.

[MPC]

Thanks Roy W. It's as I suspected, but it's good to get other opinions on one of the more testing of Damselflies.


MPC.