Summary details for Neon valentulus Falconer, 1912

Distribution

This species is restricted to a few fenland sites in a relatively small area of East Anglia. It has been recorded from Cambridgeshire (Wicken and Chippenham Fens), West Norfolk (Foulden Common), East Norfolk (Roydon Fen), West Suffolk (Pashford Poors Fen) and East Suffolk (Redgrave Fen). An early record from Essex (Hull 1948) is unlikely and a record from Box Hill (Surrey) has proved on re-examination to be N. reticulatus. In Europe the species has been recorded from France, Belgium, the Netherlands, Sweden, Germany, Switzerland, Austria, the Czech Republic, Romania and Poland.

Habitat and ecology

The spider is found in grass and moss in sedge fens. At Redgrave Fen it has also been recorded in Molinia, Cladium and Juncus. Adults are normally found in May and June but females were taken at the end of July at Roydon Fen.

Status

Although the spider has been reported regularly in the past at Wicken and Chippenham Fens, Cambridgeshire and Foulden Common, West Norfolk, the only recent records are from Roydon Fen, Diss in 1990 and from Wicken Fen in 1999. There appears to have been a serious decline in area of occupancy from six hectads prior to 1992 to just one after that date.

Threats

All the sites at which this spider has been recorded are either National or Local Nature Reserves and four (Wicken Fen, Pashford Poors Fen, Redgrave Fen and Foulden Common) are SSSIs. As with other fenland species, drainage of the East Anglian fens for agriculture has lowered the water table over a wide area. This, together with water abstraction for irrigation and public water supplies has decreased flows of water from springs on which many of the valley fens in the area depend. At many of these sites, drying out of soils has been accompanied by invasion of open fen communities by willow and birch scrub and, eventually conversion to carr woodland.

Management and conservation

At Wicken, Chippenham and Redgrave Fens, the hydrology of the sites is being manipulated in an effort to maintain high water tables. At these sites, revival of sedge cutting has begun to reverse the encroachment of scrub and carr woodland onto open fen communities. While one solution might be to divert water from fenland rivers onto sites, the high nutrient load of these rivers (derived from agricultural fertilizers) can cause problems of eutrophication of soils and consequent changes to the vegetation. Text based on Dawson, I.K., Harvey, P.R., Merrett, P. & Russell-Smith, A.R. (in prep.).