Autumnal orb-weaver

Before you go all girly on me, she was about 5mm long, which in my book makes her a money spider. She was also considerably more frightened of me than you are of her, and so well-camouflaged against this dying Norway maple leaf that my aged eyes could barely make her out as she scuttled around. I just had to trust the camera and flash to do their thing, which luckily they did, and after four frames (three of them surprisingly well-focused) I carefully turned the leaf back over and left her to recover her composure.

My first thought was that she was an immature Garden Spider (Araneus diadematus), though I'd never seen one quite this colour before. But spiders are tricksy, and in fact there is a red form of that species - though this isn't it. Not only does this individual not have the cross pattern of paler marks on her abdomen that characterises A. diadematus, she's also the wrong shape. It's not as obvious from this angle as it is in my other photos, but her abdomen is quite triangular, broad at the front and narrow at the back, with three bumpy 'points'. According to the experts in the British Spiders group on Facebook, this is enough to identify her as Araneus triguttatus, the Deciduous Orb-weaver, which is very pleasing because she's the first of her kind I've ever found.

Araneus triguttatus is a woodland spider that spins its web amongst the foliage of broadleaved trees, especially oaks. According to my field guide it's restricted to the area south of a line drawn between the Severn and Humber estuaries, but within its range it can be quite common. There's a similar but smaller and less common (or at least, less recorded) species called Araneus sturmi, which frequents evergreen trees and bushes, and in theory the two species can't be distinguished without microscopic examination, but the British Spiders chaps seem fully confident that this one can be recorded as A. triguttatus.

That name, though, has been niggling me. "Guttatus" means spotted or speckled, which is a fair enough description, so you'd think that "triguttatus" would mean something like three-spotted, but that clearly isn't right here. But after wasting spending quite a lot of time this evening surfing the web, I think I've finally solved my problem. Many mature specimens of this species have a dark fore-edge to the abdomen, with a pale, roughly triangular mark above it, and in some individuals that triangular mark splits into three distinct pale spots. You have to go quite a long way down the iNaturalist gallery to see any of the three-spotted form, but on a French site I looked at (with a gallery that was much harder to access, unfortunately) they appeared to be very common. In fact all the photos I found of this form appear to be from continental Europe, and it would be interesting to know what proportion of the reported specimens in the UK show this 'classic' marking.