Mazarine Blue (Cyaniris semiargus)
Key Details
| Taxonomic Groups: | Invertebrate > insect - butterfly > Butterfly |
| 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: | Cyaniris semiargus |
| UKSI Recommended Authority: | (Rottemburg, 1775) |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Fox & Dennis, 2021 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | Mazarine Blue remains Regionally Extinct. The last record as a resident species in Britain was in 1904. The British foodplant is unknown, but presumed to be Red Clover, as most known, extinct sites were clover meadows and this is the principle foodplant for species in continental Europe. The reasons for extinction are unknown. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Research would be required to ascertain reasons for extinction and feasibility of reintroduction |
| 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: | Yes |
| Justification: | Assumption would be that availability of damp meadows with Red Clover is only requirement but would be dependent on understanding reasons for decline which are still unknown |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 4. Autecology and pressures understood |
| Recovery potential/expectation: | Low - Pressures acting outside England |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Currently extinct and only option for reintroduction is captive rearing |
Key Actions
Key Action 1
Proposed Action: Begin research on reasons for extinction and establish historic distribution
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: >10 years
Scale of Implementation: National
High priority sites:
Comments:
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.