UK populations

Discovery of the UK populations

Dolomedes plantarius was not discovered in the UK until 1956 when eminent arachnologist Dr Eric Duffey found it around the margins of peat pools at Redgrave and Lopham Fen, at the source of the River Waveney on the Norfolk/Suffolk border (Duffey 1958).


Fig. 1  Veteran arachnologist and conservationist Dr Eric Duffey who discovered D. plantarius in the UK and did much to save the population at Redgrave & Lopham Fen from extinction


A second UK population was discovered, 180 km away, when Peter Kirby identified D. plantarius from grazing marsh ditches on the Pevensey Levels in East Sussex in 1988 (Kirby 1990). This population had been known to biologists for several years but it was assumed to be D. fimbriatus. It had been known to local people for much longer and, in the 1950s, was reported to be common in the areas in which it is most still abundant.

In 2003, a third UK population was discovered on a disused canal near Swansea, South Wales, by local naturalist Mike Clark. Immature Dolomedes found on near-by Crymlyn Bog were subsequently also identified as D. plantarius. Although Dolomedes fimbriatus was reported from this site by Friends of the Earth campaigner Andrew Lees in 1978, the record was never verified. The lack of any reliable historical record for this species in Britain makes it impossible either to assess reliably the extent of its decline, or to account for its present highly disjunct distribution. However, its extreme rarity must result from the well-documented loss and degradation of wetlands in general, and of both lowland fens, and ditch systems in lowland grazing marsh, in particular.

Visit the following sections for further information on the three UK populations:

The Translocation section provided information on the programme to reduce this species' vulnerability in England by translocating it to suitable new sites.