In July 2004 Emma Costello of Igrox Ltd, a pest control
company based in Worlingworth, contacted me. A container from Angola had
arrived at Felixstowe docks and, when it was found to contain some large spiders,
Igrox were called in to fumigate it. Although this is not the standard method
for collecting and killing spiders for taxonomic study, I received three
specimens from Emma in a reasonably good condition for identification. 
One
spider was immature and I have been unable to get anywhere with naming it: I
have not been able to identify even the family it belongs to. The other two
spiders were adults, a male and a female. Even on a preliminary examination it
was clear that these adult spiders were of a species within the family
Pholcidae, the daddy-longlegs spiders, but they were obviously bigger than all
of the British representatives of this family.
Pholcid spiders mainly occur in the warmer regions of the world, either in caves or in association with man. They often feed on other spiders such as Tegenaria house spiders, the ones that you find in the bath. Their venom is a powerful neurotoxin, one of the most powerful spider venoms known, according to some authorities. However, they have very weak jaws incapable of piercing human skin and their venom glands contain only small doses of the poison, too small to pose a risk to a human.
There are only two species of Pholcid that have been recorded from Britain and both are normally found in and around buildings where there is human activity. The most frequently seen is the long-legged spider, Pholcus phalangioides, which can grow to 10mm in length but is normally only three quarters of this size. I described the appearance and discussed the Suffolk distribution of this species in this White Admiral several years ago (Lee, 2000). In the same article I also mentioned the second species, Psilochorus simoni, a miniature version of P. phalangioides growing to only 2.5mm in length. Although similar in body length to the very largest P. phalangioides, the specimens from Felixstowe had longest leg lengths in excess of 55mm. The body was also more globular than in Pholcus and therefore gave the spiders a much bulkier appearance as well.
In addition to their overall appearance (Fig. 1), I had placed the spiders in the Pholcidae on the basis of their eye pattern. The eight eyes were in the typical Pholcid arrangement of two lateral groups of three with an anterior median pair (Fig. 2). Confident in the identification of the family, I turned to the Internet for help with determining the species. There I came across the website of an Austrian arachnologist, Dr Bernhard Huber, who specialises in the Pholcidae (http://b.a.huber.bei.t-online.de/homepage/). Dr. Huber kindly agreed to look at the Felixstowe spiders but rather than send the actual specimens by post, I sent drawings of the male palpal organs and chelicera by e-mail. From these drawings he was able to identify the species as Artema atlanta.
Artema atlanta was originally described as a species new to science 168 years ago. The specimens described had been collected in Brazil but Brignoli (1981) suggests that the species was introduced to the Americas from the Old World. Thus, even early in the nineteenth century, this tramp species appears to have been hitching a lift with man on his travels around the globe. It has now been reported from all the continents except Antarctica and has become an established part of the fauna where warmer temperatures allow. In 2001 it was reported as being imported into Antwerp (van Keer & van Keer, 2001), not that far from Felixstowe as the ferry sails!
The presence of two specimens of Artema atlanta in a container on Felixstowe Docks hardly merits an addition to the county checklist. However, it does further demonstrate the potential for the introduction of alien species and the risk of their becoming established should climatic change be favourable.
Fig. 1 Male Artema atlanta seen from above. Only coxae and trachanters of legs are shown. Scale bar is 5mm.
Fig. 2 Anterior of carapace of Artema atlanta showing typical Pholcid eye pattern. Scale bar is 1mm
References
Brignoli, P. M. 1981. Studies on the Pholcidae, I. Notes on the genera Artema and Physocyclus (Araneae).
Bull. Amer. Mus. Nat. Hist. 170(1): 90-100.
Lee, P. 2000. Further notes on the long-legged spider, Pholcus phalangioides. White Admiral. 45: 39.
van Keer, K., & van Keer, J. 2001. Ingeburgerde exotische trilspinnen (Araneae: Pholcidae) in Antwerpse haven en enkele algemene bedenkingen bij spinnenmigratie. Nwsbr. Belg. Arachnol. Ver. 16(3): 81-86.
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