Hydroporus scalesianus
Key Details
| Taxonomic Groups: | Invertebrate > insect - beetle (Coleoptera) > Water beetle |
| 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: | Hydroporus scalesianus |
| UKSI Recommended Authority: | Stephens, 1828 |
| UKSI Recommended Qualifier: | (none specified) |
| Red List Citation: | Foster, 2010 |
| Notes on taxonomy/listing: | (none) |
Criteria
| Question 1: | Does species need conservation or recovery in England? |
| Response: | Yes |
| Justification: | Hydroporus scalesianus is currently known from around a dozen hectads in England, concentrated in Norfolk but with 4 far-flung outliers. Subfossil and historic records show it was once much more widely distributed (Foster et al 2016): it has been recorded from 14 hectads in England since 1980 with earlier records from 3 further hectads; subfossils have been reported from 9 additional locations. It is restricted to relict-fens and is likely incapable of dispersal other than very locally. Loss of any population, especially outside Norfolk, would increase the risk of national extinction. |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | H. scalesianus is capable of persisting indefinitely in small and isolated fens, the Durham and Dorset sites being good examples. However, such sites require active measures to protect hydrological integrity and water quality, and management to control scrub encroachment. Targeted small-scale works are likely needed. This species may be less vulnerable in larger sites in Breckland and Broadland where management to maintain overall favourable condition should ensure its survival. |
| 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: | H scalesianus is too localised to benefit from wider countryside measures. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 4. Autecology and pressures understood |
| Recovery potential/expectation: | Unknown |
| National Monitoring Resource: | Opportunistic - insufficient |
| Species Comments: | Ad hoc recording as part of GB water beetle recording scheme (Balfour-Browne Club/Aquatic Coleoptera Conservation Trust). Additional action proposed: Ensure that this species and its requirements are considered in SSSI and nature reserve management plans & prescriptions, agreements, water level management plans etc. |
Key Actions
Key Action 1
Proposed Action: Make an inventory of all protected sites with post-1980 records. Consider opportunities for listing this species as a site 'feature' (e.g. review of SSSI citations).
Action targets: 5. Remedial action identified
Action type: Site protection
Duration: 2 years
Scale of Implementation: National
High priority sites: Records have been mapped in Atlas 1 (Foster et al, 2016).
Comments: Relevant to all sites in inventory.
Key Action 2
Proposed Action: Undertake a review of this species and other water beetles dependent on relict-fens in order to promote better understanding of their conservation requirements. Hydroporus scalesianus belongs to a suite of water beetles closely associated with remnant fens; others include Agabus striolatus, Dryops anglicanus, D. auriculatus, D. griseus, Helochares obscurus, Hydrochus brevis, H. ignicollis, H. megaphallus, Hydroporus elongatulus, H. glabriusculus, Laccornis oblongus and Limnebius aluta.
Action targets: 4. Autecology and pressures understood
Action type: Scientific research
Duration: 1 year
Scale of Implementation: National
High priority sites:
Comments:
Key Action 3
Proposed Action: In consultation with local stakeholders, assess any habitat management actions necessary to maintain/restore favourable conditions at the sites in Cumbria (Biglands Bog), Durham (Hart Bog), East Yorks (Hornsea Mere) and Dorset (Morden Bog). These are likely to be small-scale works needed, for example, to prevent water loss or scrub encroachment.
Action targets: 5. Remedial action identified
Action type: Habitat management
Duration: 3-5 years
Scale of Implementation: ≤ 5 sites
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.