Adicella filicornis
Key Details
| Taxonomic Groups: | Invertebrate > insect - caddis fly (Trichoptera) > Caddisfly |
| Red List Status: | Endangered (Not Relevant) [EN(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: | Adicella filicornis |
| UKSI Recommended Authority: | (Pictet, 1834) |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Wallace, 2016 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | IUCN Endangered status awarded due to lack of modern records due to lack of focussed surveys. It has subsequently been re-found at many of its old sites but remains, and can be anticipated to remain, a rare species of very small sites that are vulnerable to damage. English sites are 4 near Scarborough, (2018 records) 4 in South East Devon (1981 records) and 1 Scottish record (2018) and 4 Welsh sites (2016). |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | The widely scattered records and their general isolation from neighbouring populations suggests it is a poor disperser so not able to take advantage of any increase in potential sites. It will have also have probably adapted to each site and the springs and trickles where it lives are very small and can be damaged during general larger site management e.g. culverting to prevent damage to footpaths. |
| 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 rare species seems too widely dispersed to benefit from generalised habitat diversification and its woodland spring habitat is difficult to reproduce. The cliff habitat is a product of ground instability, also difficult to reproduce. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 2. Biological status assessment exists |
| Recovery potential/expectation: | Low - Relict or natural rarity |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Whilst classifying this species as having low potential to become one of Least Concern, there can be confidence it can be maintained at its existing sites and that there will be an occasional additional population discovered. |
Key Actions
Key Action 1
Proposed Action: Advise land managers on the exact sites for the species and not to overlook their existence in management plans. This can be achieved through site visits to obtain photos and accurate grid references and in-person advice to site managers including habitat management advice. Other rare species may occur at the same site or nearby and it is very cost effective to ensure there is a meshing with plans for those species.
Action targets: 5. Remedial action identified
Action type: Advice & support
Duration: 1 year
Scale of Implementation: ≤ 10 sites
High priority sites:
Comments: One visit per site would probably suffice and they are clumped with a group near Scarborough and a group in south east Devon.
Key Action 2
Proposed Action: Provide identification materials to assist surveyors of calcareous spring complexes in woodland and soft rock cliffs to recognise this species. It will be cost effective to cover other species of the habitat in any materials produced.
Action targets: 8. Species recovering
Action type: Advice & support
Duration: 1 year
Scale of Implementation: ≤ 5 sites
High priority sites:
Comments: Finding additional modern sites reduces risk of extinction.
Key Action 3
Proposed Action: Whilst suggesting specific advice for this species it would benefit from general advice about managing and surveying this particular habitat such as the ground instability that A fiicornis and other species seem to require.
Action targets: 5. Remedial action identified
Action type: Advice & support
Duration: 1 year
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.