Summary details for Rosser's Sac-spider (Clubiona rosserae Locket, 1953)

Species Details

Species name: Clubiona rosserae Locket, 1953
Common name: Rosser's Sac-spider
Taxonomy: Animalia :: Araneae :: Clubionidae
habitat: acid & sedge peats

Distribution

Only known from two sites in Britain: Chippenham Fen, Cambridgeshire - the type locality - where it has been recorded on a number of occasions since it was first found there in 1951; and a single female found in a water trap at Botany Bay, Lakenheath Fen RSPB reserve, Suffolk in April 2000. The record from Tuddenham Fen, West Suffolk mapped in the Provisional Atlas is now known to be erroneous. In Europe it is recorded from only a few countries, including the Netherlands and Poland.

Habitat and ecology

Confined to fens where it is found among cut sedge and reeds and in sedge tussocks. Adults have been collected in every month between February and October, except March and August, suggesting an extended period of adult activity.

Status

UK Biodiversity Action Plan priority species. Known from two sites, one the type locality, where it has been recorded on a number of occasions, and at the other just one specimen has been found. The population at Chippenham Fen appears to be established but dedicated survey work between 2002 and 2005 failed to refind it there or at Lakenheath Fen

Threats

Chippenham Fen is a National Nature Reserve, and Lakenheath Fen an RSPB reserve. In its principal site at Chippenham Fen, water abstraction in the surrounding area is thought to have reduced water levels in the fen.

Management and conservation

Management at Chippenham Fen is aimed at maintaining a high ground water table and preventing carr woodland encroaching on open sedge beds by a regime of annual mowing and grazing. Grazing has also been reintroduced to Botany Bay by the RSPB, and water levels are controlled to keep the site wet. Further survey work is needed to establish the continued presence of this species at these two sites, and to discover new sites, and then to carry out research on its ecology to enable best management practice to benefit the species. Text based on Dawson, I.K., Harvey, P.R., Merrett, P. & Russell-Smith, A.R. (in prep.).

Stats

First recorded: 1951
Last recorded: 2024
Total records: 38
Total visits: 32

Conservation status

Clubiona rosserae

Source	Reporting category	Designation	Date designated	Comments
A Review of the scarce and threatened spiders (Araneae) of Great Britain: Species Status No. 22 (Sep 2017)	Rare and scarce species	Nationally Rare. Includes Red Listed taxa	01/09/2017
A Review of the scarce and threatened spiders (Araneae) of Great Britain: Species Status No. 22 (Sep 2017)	Red listing based on 2001 IUCN guidelines	Vulnerable	01/09/2017	Known from just two sites. At Chippenham Fen, the type locality, it has been recorded on a number of occasions, most recently, in one small area, in 2010 after a 14 year interval. At its other site just one specimen has been found, in 2000. Potential threats include eutrophication of ditch habitat, and changes to management. Its highly restricted occurrence, and our lack of understanding of the reasons for this, mean that the species is capable of rapidly becoming Critically Endangered. Threats: Chippenham Fen is a National Nature Reserve, and Lakenheath Fen an RSPB reserve. In its principal site at Chippenham Fen, water abstraction in the surrounding area is thought to have reduced water levels in the fen. Eutrophication and changes in management are also potential threats.
Natural Environment and Rural Communities Act 2006 - Species of Principal Importance in England (section 41)	Biodiversity Lists - England	England NERC S.41	01/11/2008
UK list of Priority Habitats and Species	Biodiversity Action Plan UK list of priority species	Priority Species	28/08/2007	status on former BAP list- Species Action Plan

Photos and media

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Spatial distribution - hectad map

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Temporal distribution - records by year

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