Chrysotus collini
Key Details
| Taxonomic Groups: | Invertebrate > insect - true fly (Diptera) > Long-legged fly |
| 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: | Chrysotus collini |
| UKSI Recommended Authority: | Parent, 1923 |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Drake, 2018 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | Two records in past ten years 2016 and 2023 both on protected sites so potential for positive recovery action |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | With few records in the previous 10 years the need for at least ongoing surveying to establish whether populations at known sites persist. |
| 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: | Records from Steart Marshes WWT in Somerset show that reinstated coastal marshland may attract this species. Also found to be widespread on the PFA ashfields at Tilbury in 2024. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 2. Biological status assessment exists |
| Recovery potential/expectation: | Low - Life history factor/s |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Most sites that the fly has been recorded since 1990 have been SSSI. Latest records from Steart Marshes WWT Somerset and Elmley Marsh NNR in Kent. |
Key Actions
Key Action 1
Proposed Action: Tailored surveys of potential habitat in known or potential habitat localities to determine the populations and species distribution, thus identifying areas where C. collini is missing as well as present.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: ≤ 10 sites
High priority sites: Steart Marshes WWT Somerset and Elmley Marsh NNR Kent.
Comments: Baseline surveys of potential sites both to establish where present but also where missing.
Key Action 2
Proposed Action: Based on outcomes of Action 1, provide advice and support to guide design of coastal flood defences to ensure habitat for this species is created/managed correctly
Action targets: 4. Autecology and pressures understood
Action type: Advice & support
Duration: >10 years
Scale of Implementation: ≤ 5 sites
High priority sites: Elmley Marsh NNR Kent if populations are found to be present
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.