Rosser's Sac-spider (Clubiona rosserae)
Key Details
| Taxonomic Groups: | Invertebrate > spider (Araneae) > Spider |
| Red List Status: | Vulnerable (Not Relevant) [VU(nr)] |
| D5 Status: | Included in the baseline Red List Index for England (Wilkins, Wilson & Brown, 2022) |
| Section 41 Status: | (not listed) |
| Taxa Included Synonym: | (none) |
| UKSI Recommended Name: | Clubiona rosserae |
| UKSI Recommended Authority: | Locket, 1953 |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Harvey et al., 2017 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | VU, criteria: D2: Recorded in GB only from E. Anglia, and only reliably from a single site. Targeted searches have not re-found it again at a second site, where single individual was recorded in 2000. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Apparently occupying very little of its highly fragmented habitat. |
| Question 3: | At a landscape scale, would the species benefit from untargeted habitat management to increase habitat mosaics, structural diversity, or particular successional stages? |
| Response: | No |
| Justification: | This species would not benefit from untargeted management |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 2. Biological status assessment exists |
| Recovery potential/expectation: | Low - Combination or other (detail in comments) |
| National Monitoring Resource: | Combination - insufficient |
| Species Comments: | Confined to E. Anglian Fens where it is most easily found in cut litter piles. Distribution suggests low dispersal ability and narrow niche requirements, still awaiting full characterisation. Desiccation of fens due to climate change likely to limit and recovery but extinction debt can't be excluded. |
Key Actions
Key Action 1
Proposed Action: Re-assess status by repeating the unsuccessful 2002/04 (Buglife) surveys in the light of more recent knowledge of microhabitat requirements and phenology.
Action targets: 2. Biological status assessment exists
Action type: Status survey/review
Duration: 2 years
Scale of Implementation: ≤ 10 sites
High priority sites:
Comments: Cover all fens previously surveyed. To be done in peak activity period of Oct/Nov.
Key Action 2
Proposed Action: Autecological research to better characterise habitat requirements and inform management
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 3-5 years
Scale of Implementation: 1 site
High priority sites: Chippenham Fen, Cambs.
Comments: Include any other sites identified as a result of status survey (Action 1)
Key Action 3
Proposed Action: If no further populations found by 2025 (Action 1), start 3 year process of evaluating possible translocations (informed by Action 2)
Action targets: 7. Best approach adopted at appropriate scales
Action type: (Re-)introduction
Duration: 3-5 years
Scale of Implementation: ≤ 5 sites
High priority sites:
Comments: Potential receptor sites will be identified as part of the evaluation process
Acknowledgment:
Data used on this website are adapted from Threatened species recovery actions 2025 baseline (JP065): Technical report and spreadsheet user guide (Natural England, 2025). Available here.