Mastigusa arietina
Key Details
| Taxonomic Groups: | Invertebrate > spider (Araneae) > Spider |
| Red List Status: | Regionally Extinct (GB scale) (Not Relevant) [RE(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: | Mastigusa diversa |
| UKSI Recommended Authority: | (O. Pickard-Cambridge, 1893) |
| 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: | RE: last records from first 1/4 of last century but recent molecular phylogenetic analysis suggests that all GB Mastigusa may be the same, hitherto undescribed species (Castellucci et al. 2023). |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Extreme rarity even in relation to its specialist 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): | 1. Taxonomy established |
| Recovery potential/expectation: | Unknown |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Likely taxonomic confusion with M. macrophthalma; both may be assigned to a single new species (see Col. R). Strongly associated with two ant species in parkland/wood pasture oaks. |
Key Actions
Key Action 1
Proposed Action: Taxonomic/genetic research to further investigate taxonomy of GB Mastigusa with reference to recent paper (see Col 2018 R)
Action targets: 1. Taxonomy established
Action type: Scientific research
Duration: 2 years
Scale of Implementation: ≤ 10 sites
High priority sites: Windsor Forest and similar Berks/Surrey habitat
Comments: current taxonomic research may be possible to achieve all needed via this plus DToL work
Key Action 2
Proposed Action: Targeted survey of all recorded sites and suitable nearby habitat to update status assessment
Action targets: 2. Biological status assessment exists
Action type: Status survey/review
Duration: 2 years
Scale of Implementation: ≤ 10 sites
High priority sites:
Comments: Interpretation linked to results of taxonomic research (Action 1). Surveyors need access to canopy rot holes - implications for specialist equipment and H&S. Survey to include specimens in historical collections, linked to Action 1.
Key Action 3
Proposed Action: Site management to include veteranising younger trees to maintain succession of rot holes
Action targets: 5. Remedial action identified
Action type: Habitat management
Duration: >10 years
Scale of Implementation: ≤ 10 sites
High priority sites:
Comments: Increasingly standard management practise for a wide range of invertebrates at suitable sites.
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.