Populations of two alien spiders in a Wirral garden centre

In 2019 my wife and I discovered that Gordale Garden Centre in mid Wirral (SJ3375) had a population of the Garden Centre Spider Uloborus plumipes Lucas and we have enjoyed seeing it there on our occasional visits in subsequent years. On a recent visit we were surprised to find that the spider in the web in the armpit of the model chimpanzee was not U. plumipes but a small pholcid with markings unlike the Pholcus phalangioides (Fuesslin) at home. We thought it was probably the Marbled Cellar Spider Holocnemus pluchei (Scopoli) and are happy at that identification now having seen more of them. We observed several small, and a couple of large, Holocnemus in a visit to the garden centre on May 23rd. It seemed to us that Uloborus had become scarcer, perhaps it is losing out to Holocnemus.

Holocnemus webbing on model chimpanzee

Like most large garden centres there is a large under-cover non-plant area, however, we noticed the spiders in the indoor plant area or nearby where it is a little cooler and will be more humid, but both species may be more widespread within the complex. Their distribution in the sales area might be influenced by stock movement, for example, the model chimpanzees seem very expensive [to us] and are probably not often examined with a view to purchase, and wasp trap bait is a later season need.

The British Arachnological Society maps show that Uloborus is quite common in our area but Holocnemus seems quite a jump in range. Whilst Holocnemus pluchei seems the likely species, we have preserved an individual in pure ethanol in case DNA analysis seems desirable.