Garden Centre Spider (II)

Another visit to the garden centre. I spend much of it looking up most, in search for the Garden Centre Spider, Uloborus plumipes. I must have been a funny sight. My efforts are rewarded quickly. First, and most obvious I spot the webs, stretched across the plumbing by the glasshouse roof. They are laid almost horizontally and is an orb web. This one had a stabilimentum, a decoration in the centre of the web, in this case a linear one.

The spiders were a bit harder to find. After a while I saw some piece of debris hanging from some web, see the spot in the middle of the photo?

Zooming in, it revealed itself a a superbly camouflaged spider. It is hard to think it is a spider from a distance. Once I had spotted one, more followed, and I counted five in a relatively small area. 

The nicer thing, though, was to find its spiky egg sac too.

Sorry for the poor photo quality, but the spiders were 3 m above me and the light already fading.

Garden Centre Spider

Bugblog has curled under a dry leaf and enjoyed an extended period of dormancy. The new year has brought some interesting invertebrates so I foresee some blog activity in the next few days. In a trip to the garden centre, a little spider dangled from the ceiling. Something called my attention: its front legs. They were long and robust, and adorned with dark tufts of hairs. The spider held them forward, using them as feelers as it moved. It reminded me of an orb web spider, but not one I had seen before, so I posted a photo on Twitter asking for help. Within minutes, Chris @BHWWildlifeGdn answered:

@aBugBlog uloborus plumipes? commonly known as the garden centre spider
— Chris (@BHWildlifeGdn) January 19, 2015

A close up of the spider in my hand, to give you a sense of scale

And so it was! This species has been expanding in the UK since the early 90s, when it was found in garden Centres in Reading, Liverpool and Southampton. In fact, it is not even mentioned in my spider field guides. Now it is widespread through most of England and large cities in Scotland, where it is almost exclusively found in or around heated greenhouses of garden centres, and is thought to have come with plants from Holland, where it was also found. The original distributions appears to be Africa and the Mediterranean, although it is expanding worldwide thanks to its ability to thrive in garden centres.
 Uloborids are cribellate spiders, they brush their silk with a comb-like set of bristles in their rear legs making the silk sticky. This silk is so efficient immobilising prey that uloborids have lost their venom glands, not that this makes much of a difference to us, as this species is so small its fangs will be unlikely to break the skin.
 I shall keep an eye for this unusual spider every time I visit a garden centre. It builds horizontal orb webs (although it is not a member of Araneae, but of Uloboridae) and sits underneath, resembling a fragment of dead leaf and their egg sacs are white and of an unusual shape too. Chris recommended looking around the lights.

More information
Page for Uloborus plumipes at the Spider and Harvestman recording scheme. Here.
Wikipedia page.