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Suffolk Natural History, Vol. 53
Keep an eye out for this cellar spider new to Suffolk The Marbled Cellar Spider (Holocnemus pluchei) is a native of the Mediterranean region where, despite its name, it has been found in open habitats on scrub and cactus as well as in rock crevices, cellars and houses (Le Peru, 2011). Over the last few decades the spider has been introduced much more widely across Europe and into America (Rozwalka & Stachowicz, 2010). It was first reported from Britain in 2004 (Daws, 2005) and a second population was found two years later (Taylor, 2006). More recently the spider was reported from near York on 29 July 2017 (Peter Harvey, pers. comm.) and on 12 October 2017 Rob Garrod observed what Paul Lee confirmed to be a population of the spider from a factory in Hadleigh (Grid Reference TM031434). In cooler climes, where the spider has been introduced, it becomes almost exclusively associated with man, often in heated buildings such as houses and garden centres. The Hadleigh factory is very warm all year round. Rob believes the species may have gone unrecorded here for up to two years having been overlooked as another colony of the Daddy long-legs spider Pholcus phalangioides. This latter species is believed to be of Asian origin and has become widespread across Suffolk in the last 30 years. It is found in cooler outbuildings as well as heated locations. Although superficially similar in appearance, Marbled Cellar Spiders can be distinguished from Daddy long-legs spiders on the basis of several readily observed characters. The most obvious is that the abdomen of the latter is a uniform grey to grey-brown colour (see Plate 1) but the abdomen of Marbled Cellar Spiders is patterned on both upper and lower sides (see Plates. 2 and 3). The underside is especially strikingly marked with a broad dark band. The sternum (underside of the forebody) is also dark, much more so than in Daddy long-legs spiders and the first segment of each leg, the femur, is spotted with brown. These features are shown in the images (Plates 2 & 3) of the Hadleigh spiders. It is possible that the Marbled Cellar Spider is present in other heated buildings in Suffolk, perhaps even in your own home, having been dismissed as yet more of those pesky Daddy long-legs spiders. Paul would be keen to hear from anyone who thinks they have seen the spider, especially if they can provide a good quality photo and information on when and where they saw it. References Daws, J. (2005). Holocnemus pluchei in Leicestershire. S.R.S. News. No. 51: 11 In Newsl. Br. arachnol. Soc. 102. Le Peru, B. (2011). The Spiders of Europe, a synthesis of data (volume 1) Atypidae to Theridiidae. Mémoires de la Société linnéenne de Lyon 2: 1-522. Rozwalka, R. & Stachowicz, J. (2010). Holocnemus pluchei (Scopoli, 1763) new for Poland introduced species of pholcid spider (Araneae: Pholcidae). Annales UMCS, sec. C 65(2): 73-78. Taylor, P. (2006). Discovery of Holocnemus pluchei colony at Welford, Stratford upon Avon S.R.S. News. No. 56: 16 In Newsl. Br. arachnol. Soc. 107. Rob Garrod and Paul Lee
Trans. Suffolk Nat. Soc. 53 (2017)
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Plate 2: Marbled Cellar Spider (Holocnemus pluchei) showing patterned abdomen (p. 36).
R. Garrod
Plate 1: Daddy long-legs spider Pholcus phalangioides showing uniform grey to grey-brown abdomen (p. 36).
Plate 3: Marbled Cellar Spider (Holocnemus pluchei) showing dark sternum (underside of the forebody) and underside marked with a broad dark band. The first segment of each leg, the femur, is spotted with brown (p. 36). Trans. Suffolk Nat. Soc. 53 (2017)