Mastigusa macrophthalma
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: | 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: | VU, criteria: D2: apparent continuing decline with 6 (/13) hectads since 2000. Taxonomic revision likely; recent molecular phylogenetic analysis suggests that all GB Mastigusa may be the same, hitherto undescribed species (Castellucci et al. 2023). Strongly associated with the nests of several ant species in ancient woodland but also under bark and in cavities in mature/veteran trees. |
| 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. arietina; both may be assigned to a single new species (see Col. R). Strongly associated with the nests of several ant species usually in ancient woodland/wood pasture, and under bark and in tot holes in mature/veteran trees. |
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: ≤ 20 sites
High priority sites: Windsor Forest, Breckland (new sites), Charnwood Forest, Sherwood Forest, Horner and Dunsford Woods, Devon
Comments: Sample from as many isolated GB locations as possible
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: ≤ 20 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 2
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: ≤ 20 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.