Tachytrechus ripicola
Key Details
| Taxonomic Groups: | Invertebrate > insect - true fly (Diptera) > Long-legged fly |
| Red List Status: | Critically Endangered (Not Relevant) [CR(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: | Tachytrechus ripicola |
| UKSI Recommended Authority: | Loew, 1857 |
| 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: | There is only a single English record in the past 42 years, from Studland, Shell Beach (SZ037861) in 2014 where two females were collected. The site was a SSSI and NNR so hopefully protected. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | If an existing population can be found in previous known areas (or adjacent to these) then targeted interventions may be possible. Surveying of known areas and specific habitats i.e freshwater seepages and flushes in sandy coastal areas could be protected from recreational pressures. |
| 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): | 4. Autecology and pressures understood |
| Recovery potential/expectation: | Low - Relict or natural rarity |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | The fly is a large and conspicuous Dolichopodid, thus if recording has been in place at suitable locations as it was prior to the 2018 NERC review and still only a singe record found this would imply that it is naturally rare in England. It should also be noted that the biology of the species 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 T. ripicola is present or absent so that further targeted actions can be implemented as necessary to protect the habitat.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: ≤ 5 sites
High priority sites: As a starting point: Studland, Shell Beach (SZ037861) and Arne.
Comments: Targeted surveying to establish whether populations remain both within sites and if they have spread to adjacent areas of similar habitat. Distribution appears to always have been limited in England with Dorset (VC9) the main areas being Studland and Arne
Key Action 2
Proposed Action: Where populations are discovered, implement habitat management the specific habitat the fly appears to need (based on outcomes of Action 1).
Action targets: 4. Autecology and pressures understood
Action type: Habitat management
Duration: >10 years
Scale of Implementation: ≤ 5 sites
High priority sites: As a starting point: Studland, Shell Beach (SZ037861) and Arne.
Comments: Management of the environment to protect freshwater streams and seepages the feed pools in coastal areas
Key Action 3
Proposed Action: Assessment of occupied sites if found 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: 3-5 years
Scale of Implementation: ≤ 5 sites
High priority sites: As a starting point: Studland, Shell Beach (SZ037861) and Arne.
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.