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Suffolk Natural History, Vol. 48 SPIDER RECORDER’S REPORT 2012 PAUL LEE

It is several years since I submitted a report on the Suffolk fauna and there have been a number of important discoveries and events during that period. As well as the usual additions to the county checklist there have been interesting new records for some uncommon species and an important conservation exercise involving captive breeding and the establishment of new colonies of the Fen Raft Spider Dolomedes plantarius (see p. 5). I suspect most people reading this are aware of the importance of Redgrave and Lopham Fen as the home of the Fen Raft Spider although fewer may be aware of the decline in the population there as the habitat degraded, largely as a result of water abstraction, through the second part of the twentieth century. The Biodiversity Action Plan for the spider identified captive breeding as a method of building up stocks for reinforcing the existing population and translocating to new locations. A survey of potential habitat in the Waveney Valley was undertaken by volunteers in 2008 and 2009 to make sure that small populations of the spider had not gone overlooked and to identify those sites most likely to support a successful translocation. Captive breeding work in 2010 was very successful and included some cross breeding of individuals from Redgrave and Lopham with others from the population on the Pevensey Levels in Sussex. It was feared that the genetic diversity of the Suffolk spiders may have declined too far as a result of the shrinking population and the cross breeding introduced hybrid vigour that should be beneficial to any new colonies. The first translocation took place in October 2010 when captive bred spiders were released at Suffolk Wildlife Trust’s Castle Marshes reserve near Beccles. Other spiders were released in uncolonised, but suitable, habitat at Redgrave and Lopham Fen. A further release at Castle Marshes along with one at the Trust’s Carlton Marshes reserve followed in 2011. The Fen Raft Spider is related to the common Nursery Web Spider Pisaura mirabilis and, like that species, builds a tent like structure, the nursery web, to house her eggs in the later stages of development. She guards the eggs and then the young spiderlings for a week or so after they have hatched. In July 2012, nursery webs were found at Castle Marshes indicating successful breeding and pointing to a brighter future for the species. An excellent website www.dolomedes.org.uk provides background, photos and up-to-date news on the Fen Raft Spider project. New discoveries have raised the number of species of spider known from Suffolk to 448, of which 424 species are known from v.c. 25 and 347 from v.c. 26. In 2009, during the Fen Raft Spider survey in the Waveney Valley, Pip Collyer, a Norwich based recorder, collected the comb-foot spider Enoplognatha tecta from Castle Marshes. Not only was this a first record for Suffolk, but the spider is even rarer than the target of the survey. Pip’s find was only the third British specimen of a spider previously known only from a couple of adjacent sites in Dorset. The spider was listed as Endangered (RDB1) by Bratton (1991) and had not been recorded since 1974. It will be interesting to see if the on-going conservation work with the Fen Raft Spider results in more records of this species.

Trans. Suffolk Nat. Soc. 48 (2012)


FRESHWATER SPIDER REPORT INVERTEBRATES 2012

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In September 2010, Adrian Knowles found a number of small, green spiders in his garden at Capel St Mary. These turned out to be Nigma walckenaeri, yet another new species for the county. This spider may have been introduced to Britain relatively recently. Adrian considers it possible the spider may have hitched a lift to Suffolk when he moved from his previous home in Colchester. When Sue Telling purchased a bunch of grapes from an Ipswich supermarket in 2010 she got more than she bargained for. Once at home she noticed a silken retreat attached to the stem of the grape bunch but did not see the spider that had spun it. When Colin Hawes passed the grapes to me the recently dead (squashed) male spider in the bottom of the bag proved to be a Pantropical Jumper Plexippus paykulli. This spider would not have survived our climate, but has been spread around the world by man. Another jumping spider found for the first time in Suffolk in 2010 was Synageles venator. Ray Ruffell collected a female of this ant mimic running around with Black Ants Lasius niger agg. on shingle at Bawdsey Manor. This spider is nationally scarce and probably native to coastal habitats such as sand dune and shingle but also occurs in brownfield sites. Almost a year to the day after his discovery at Bawdsey, Ray added another species to the county list when he discovered one of the pirate spiders Ero aphana on gorse at Suffolk Wildlife Trust’s Newbourne Springs reserve. Pirate spiders are only 3 or 4 mm long but have evolved a very specialized feeding technique. They prey exclusively on other spiders much larger than themselves. They lure a spider out of its retreat and onto its web by plucking the strands to simulate a potential mate. The unsuspecting victim is bitten in the leg and the pirate spider quickly retreats until its venom has paralysed its prey. The pirate spider then returns to suck out the liquefied body contents through the punctured leg. Alan Thornhill added this species and Ero tuberculata to the v.c. 26 list when he recorded them from Hinderclay Fen and Cavenham Heath respectively in 2012. Lakenheath Fen is one of only two sites in the country where Rosser’s Sac Spider Clubiona rosserae has been found but it has not been seen there for more than a decade. Buglife asked Alan Thornhill to undertake some surveys of the Botany Bay area of the reserve in 2011. Unfortunately, Alan could not find the target species, but he did collect a small money spider Carorita paludosa that was new to the county. This spider was not known to science until 1971 since when it had been collected most commonly from several places within the Norfolk Broads. Otherwise it is known from a handful of sites, just one other in Britain, making the Lakenheath population of international importance for the conservation of the spider. In June 2011, the British Arachnological Society returned to Suffolk for their annual weekend field meeting at Belstead House. One of the main aims of the meeting was to search for Midia midas, a small money spider found in

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Suffolk Natural History, Vol. 48

old bird nests, squirrel dreys and similar accumulations of debris in trees in ancient woodland. Captain’s Wood, a Suffolk Wildlife Trust reserve near Sudbourne was visited during the weekend, but unfortunately the spider could not be found. A number of rare species were collected such as the RDB1 money spider Trichoncus affinis at Shingle Street, but these were well known from previous visits to the sites. What came as a complete surprise was the collection by Greg Hitchcock of a female money spider that seems to be not just a new Suffolk species, but a new British species. The spider was found in litter below heather on Upper Hollesley Common, but has not been identified as yet. Although a provisional identification has been made, comparison of the Suffolk specimen with Finnish material is not conclusive and further survey work is needed to search for male spiders. As a general rule, male spiders have more distinct characteristics that can be used in identification so this is not an unusual situation. References Bratton, J. H. (ed.) (1991). British Red Data Books 3: invertebrates other than insects. Peterborough: JNCC. Paul Lee 33 Lawford Place Lawford Manningtree CO11 2PT

Trans. Suffolk Nat. Soc. 48 (2012)

SPIDER RECORDER’S REPORT 2012  

Paul Lee

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