One-grooved Diving Beetle (Bidessus unistriatus)
Key Details
| Taxonomic Groups: | Invertebrate > insect - beetle (Coleoptera) > Water beetle |
| 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: | Bidessus unistriatus |
| UKSI Recommended Authority: | (Goeze, 1777) |
| 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: | Confined to England in GB and categorised CR. Also a S41/UKBAP species. There are more subfossil records as there are post 1980 hectads, so this species had a wider range in the past, though it has always been very rare in England since entomological recording began. Subfossil records for 6 hectads, pre-1980 records for 17 and 5 for 1980 onwards (Foster et al, 2016). |
| Question 2: | Does recovery/ conservation depend on species-specific actions? |
| Response: | Yes |
| Justification: | Yes response, but with the caveat that this may be a 'naturally rare' species in England. Recorded from only 5 post-1980 hectads in England (Foster et al 2016) but intensive surveys of New Forest sites in 2015-16 failed to detect the species and it may now be extinct there. |
| 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 requirements of this species are poorly understood and it is too rare to benefit from generic measures. |
Species Assessment
| Current step on the Species Recovery Curve (SRC): | 6. Recovery solutions trialled |
| 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). |
Key Actions
Key Action 1
Proposed Action: Review findings of any survey work undertaken towards UK SAP and more recent New Forest survey; identify and implement any practical conservation recommendations. This review may also identify gaps in survey coverage and gaps in knowledge of the species' conservation requirements, which could be addressed in future reviews.
Action targets: 5. Remedial action identified
Action type: Scientific research
Duration: 1 year
Scale of Implementation: Not applicable
High priority sites: Post-2000 records are from the Norfolk Broads (Hickling Broad & Catfield Fen) and the New Forest (Crockford Bridge marl pit complex). The latter area was re-surveyed in 2015-16.
Comments:
Key Action 2
Proposed Action: Subject to discussion with local experts and land owner agreement, consider management of Crockford Bridge marl pit complex to restore further ponds to create warm, sunlit, shallow muddy margins with short/patchy vegetation. The recent survey report describes most of the ponds as over-shaded.
Action targets: 6. Recovery solutions trialled
Action type: Habitat management
Duration: 2 years
Scale of Implementation: 1 site
High priority sites: Crockford Bridge marl pits complex, New Forest (SZ350990). This site has provided records of B. unistriatus from 1999-2014. It is part of the New Forest SSSI.
Comments: First seek advice from local experts including SSSI officer, NFNPA, Freshwater Habitats Trust and others.
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.