Thanatus formicinus
Key Details
| Taxonomic Groups: | Invertebrate > spider (Araneae) > Spider |
| Red List Status: | Critically Endangered/Possibly Extinct (Not Relevant) [CR(PE)(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: | Thanatus formicinus |
| UKSI Recommended Authority: | (Clerck, 1757) |
| 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: | CR(PE), criteria: B2ab(iv): No longer (PE) though still CR with discovery of one new population. Extremely vulnerable, apparently with only 1 extant GB population (Clumber Park, Notts) despite targeted searches in its 3 former S heathland sites. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Extremely vulnerable, apparently with only 1, very small, extant site, despite availability of other apparently suitable 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: | Structured - insufficient |
| Species Comments: | Found on wet heath margins in mature Calluna/Erica tetralix/Molinia caerulea heathland in former Ashdown Forest sites but on mid-successional, dry Calluna heathland in Nottinghamshire. Monitoring in place at extant site but reliable delivery needs more resources. Extremely vulnerable to heathland fires. Recovery potential low; likely natural rarity plus range of potential climate change impacts. |
Key Actions
Key Action 1
Proposed Action: Targeted survey of all recorded sites, similar habitat nearby and throughout E England, using standardised methodology to confirm 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: ≤ 5 sites
High priority sites: Ashdown Forest, Lincolnshire cover sands heaths, wider Sherwood/Budby Forest heaths.
Comments: Discovery at Clumber Park, 300km from former locations, opens possibility of undiscovered populations.
Key Action 2
Proposed Action: Start evaluation of translocation, in the first instance within the Clumber/Sherwood/Budby heathland complex
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: Sherwood Forest complex
Comments: 3 year assessment period following IUCN/JNCC guidelines will include input from Actions 1 and 3, and include autecological research. Costs of evaluation will depend on extent of volunteer input although it is not expected to be delivered without professional time. If eventually implemented, costs will depend on method recommended during evaluation phase.
Key Action 3
Proposed Action: Autecological research particularly to characterise microhabitat 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: Clumber Park, Long Valley
Comments: Essential to inform planned habitat recreation/connectivity for the species and the translocation evaluation (Action 2).
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.