Muscidideicus praetextatus
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: | Muscidideicus praetextatus |
| UKSI Recommended Authority: | (Haliday, 1855) |
| 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: | Repeated records in two areas of England; Dawlish Warren (VC3) in Devon and coastal saltmarshes in Norfolk (VC27,28) but not any other well surveyed similar habitats. (other records in Wales and Scotland are equally isolated/spaced without records between the sites). |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Any actions are most likely going to be site specific, the fly seems to be scarce, so targeted actions at known sites would be necessary. |
| 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: | The fly is found in saltmarshes but the areas are isolated with areas between of seemingly similar habitat, being uninhabited. This would intimate that the fly has specific (unknown) requirements and/or a low potential for dispersal. |
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: | The fly is an obligate saltmarsh occupant, distribution is sparse in England and a full understanding of the flies requirements beyond 'saltmarsh' is unknown. |
Key Actions
Key Action 1
Proposed Action: Tailored surveys of habitat in known localities to determine the population and species distribution, thus identifying whether M. preatextatus is present or absent so that further targeted actions can be implemented.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: ≤ 10 sites
High priority sites: Dawlish Warren (VC3) in Devon and coastal saltmarshes in Norfolk (VC27,28)
Comments: Targeted surveying to establish whether populations remain both within sites and if they have spread to adjacent areas of similar habitat.
Key Action 2
Proposed Action: Assessment of occupied sites and those adjacent unoccupied sites to explore habitat niche and any see if any specific requirements can be identified.
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 2 years
Scale of Implementation: ≤ 5 sites
High priority sites: Dawlish Warren (VC3) in Devon and coastal saltmarshes in Norfolk (VC27,28)
Comments: Essential to understand the water chemistry here as well as the other habitat resources.
Key Action 3
Proposed Action: Actions designed to improve or enhance site condition based on previous site assessment and action 1 & 2.
Action targets: 5. Remedial action identified
Action type: Habitat management
Duration: Unknown
Scale of Implementation: ≤ 10 sites
High priority sites: Dawlish Warren (VC3) in Devon and coastal saltmarshes in Norfolk (VC27,28)
Comments: Targeted actions would soley be dependent on the results of the previous survey/assessment. Projected actions could be maintenance of current tidal processes and controlling of grazing intensity to maintain site quality.
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.