Thames Ramshorn (Gyraulus acronicus)
Key Details
| Taxonomic Groups: | Invertebrate > mollusc > Mollusc (non-marine) |
| 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: | Gyraulus (Gyraulus) acronicus |
| UKSI Recommended Authority: | (A. Férussac, 1807) |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Seddon et al., 2014 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | In England on Red List as VU (but now probably CE). It has not been found living in last 3 years despite searches in many pre-known localities. Whole of GB location is on Upper Thames catchment |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Due to the lack of knowledge on current status or distribution a complete re-survey in all previously known river catchments is required to establish whether the species is still extant. |
| 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 - Pathogen, hybridisation, INNS |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Control of NNS (Signal crayfish) on a landscape scale may be key as there is circumstantial evidence that significant declines (extinction?) are due to Signal Crayfish |
Key Actions
Key Action 1
Proposed Action: Re-survey all previously known sites to establish if species is still present or it has gone extinct.
Action targets: 3. National Monitoring Plan agreed and implemented
Action type: Targeted monitoring
Duration: 2 years
Scale of Implementation: ≤ 50 sites
High priority sites: Upper Thames Catchment (esp. the rivers Evenlode, Windrush, Pang, Back Water
Comments: The whole of the Upper Thames requires re-surveying and could be completed in 2 field seasons. It should be repeated several times to establish whether it is extinct.
Key Action 2
Proposed Action: Following on from Action 1, update the Red list from VU (vulnerable) to at least EN (endangered) or if surveys continue to find no live populations the Cr (critically endangered)
Action targets: 2. Biological status assessment exists
Action type: Status survey/review
Duration: Unknown
Scale of Implementation: National
High priority sites: Upper Thames Catchment (esp. the rivers Evenlode, Windrush, Pang, Back Water
Comments:
Key Action 3
Proposed Action: In addition to establishing current distribution under Action 1, assess site characteristics, ownerships and management of such sites to inform pressures on species. This analysis could be done as part of a survey, in conjunction with Environment Agency information on the presence of non-native crayfish.
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 2 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.