Cloud-living Spider (Semljicola caliginosus)
Key Details
| Taxonomic Groups: | Invertebrate > spider (Araneae) > Spider |
| Red List Status: | Endangered (Not Relevant) [EN(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: | Semljicola caliginosus |
| UKSI Recommended Authority: | (Falconer, 1910) |
| 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: | EN, criteria: B2ab(ii,iv): conspicuous and continuing decline in Pennine and Lake District strongholds which have the greater part of the GB population. Scattered records from Scotland but may be under-recorded there. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Distribution more fragmented than apparently suitable upland mire 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: | Opportunistic - insufficient |
| Species Comments: | Found, sometimes in water, on the edges of Sphagnum-filled pools and drainage gulleys. Dies-out as peat dries/oxidises. Adult season throughout year but probably peaks in winter. Recovery potential likely to be limited by climate change (drought) but may also be a natural rarity. |
Key Actions
Key Action 1
Proposed Action: Targeted survey at all recorded and apparently suitable nearby sites using standardised methodology to assess current status (and establish baseline for national monitoring programme)
Action targets: 2. Biological status assessment exists
Action type: Status survey/review
Duration: 2 years
Scale of Implementation: ≤ 50 sites
High priority sites: Suction sampling is essential for any survey, and any pitfall trapping should place the traps flush with the peat floor beneath the Sphagnum acrotelm, rather than in the lawn and the trap surface flush with the vegetation.
Comments: Prioritising the 14 (/22)sites where it has not been recorded for >30 years. Survey needs to be repeated in, at least, each of 2 successive years to allow for possibility of substantial interannual differences. Use recent expertise in finding it when surveying former sites; aerial images can be used to identify possible new sites. Significant H&S issues with survey for this species - best practise for very wet sites to be strictly observed.
Key Action 2
Proposed Action: Autecological research to establish microhabitat requirements and inform management
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: >10 years
Scale of Implementation: ≤ 5 sites
High priority sites: North Pennine and central Lake District Mosses
Comments:
Key Action 3
Proposed Action: Provide targeted advice to project/land managers of peatland management/restoration/re-creation restoration projects (including palludiculture) in relevant areas, on the species location/s and habitat/management requirements (informed by actions 1 and 2) to avoid damage to current resource and maximise new colonisation opportunities.
Action targets: 5. Remedial action identified
Action type: Advice & support
Duration: 3-5 years
Scale of Implementation: ≤ 20 sites
High priority sites: North Pennine and central Lake District Mosses
Comments: A liaison action for BAS, NE and site managers.
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.