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Margaret River Ground Beetle (Trichosternus relictus)

The Margaret River Ground Beetle is a poorly known ground beetle recorded from south-western Western Australia, with habitat information pointing to wetter, more heavily forested environments. It is listed as DBCA Priority 3 in Western Australia. Plan works in potential habitat cautiously, as its on-ground requirements are not well documented.

Conservation status

Western Australia, WA Threatened and Priority Fauna List: Priority 3.

Seasonal planning

Seasonal activity, breeding and movement have not been reported for T. relictus. Plan survey and works precautions across the year unless a specialist provides better species-specific information.

Known seasonal timing: Not recorded.

Planning approach: Use the full year as a precautionary planning window, not as evidence that the beetle is equally detectable or active in every season.

No month-specific information for this species is available.

  • Survey and works planning: No seasonal activity period is known. This is a year-round planning window only, not a species-specific activity or detectability claim.

Identification: Appearance and size

External identification details are limited. Have a suitably qualified beetle specialist confirm identification where a record could affect works.

The external appearance and body size of T. relictus have not been described. General descriptions of other Trichosternus species do not necessarily apply to this species.

Identification: Similar species

Trichosternus can be difficult to distinguish from related ground beetle genera. Nurus is particularly similar, but there is no field key for separating T. relictus from other species or genera.

  • Do not rely on colour, size or general body shape alone for a species-level identification.

Identification: Field signs

No species-specific tracks, burrows, feeding signs or other field signs have been recorded. There is no reliable field sign for confirming presence.

Distribution: Known range

T. relictus is an isolated south-western Western Australian member of a genus otherwise centred in eastern Australia. Its distribution and exact occupied sites are poorly documented.

T. relictus is a single isolated species in the south-west corner of Western Australia. Atlas of Living Australia records show 14 Western Australian records in two distinct 0.1-degree locations, between latitude -34 and -33.9 and longitude 115 and 115.1. These are coarse record locations, not precise site coordinates.

Distribution: WA regions and records

The DBCA Priority Fauna List flags the South West region. The DBCA common name refers to Margaret River, but this is not established as a precise record locality. A desktop assessment also refers to a generalised record near Gnarabup and considers coastal heath there unlikely to support the species.

Habitat: Reported habitat

The clearest habitat information associates the beetle with wetter, more heavily forested environments. Detailed site requirements are not known.

T. relictus is known from wetter, more heavily forested environments. Its vegetation type, soil, moisture thresholds and landscape position have not been specified.

Habitat: Habitat limits

Coastal heathland at the Gnarabup project area is considered unlikely to support the species, despite the proximity of a generalised record. This project-specific assessment does not mean that all coastal sites are unsuitable.

Foraging habitat: Diet and feeding

The species' diet and foraging sites have not been documented. Feeding behaviour reported for other carabids is not established for this beetle.

No prey, diet or feeding behaviour has been recorded for T. relictus. Predatory habits reported for Morion species do not establish this species' diet.

Foraging habitat: Potential foraging areas

No particular litter layer, soil surface, log, under-bark site or other foraging microhabitat has been identified for T. relictus. As a precaution, inspect suitable wetter, more heavily forested habitat rather than focusing searches on an assumed feeding substrate.

Breeding habitat: Breeding information

Breeding sites, timing and reproductive outcomes are not known. A reported anatomical feature does not establish where or when the species breeds.

The breeding season, egg numbers, larval habitat and reproductive mode of T. relictus have not been established.

Breeding habitat: Reported anatomy

A long, concertina-like internal passage has been described in the female reproductive tract. A possible relationship to viviparity was suggested in the cited literature, but its function is unknown.

Sheltering habitat: Known shelter sites

Specific shelter sites have not been recorded for this species. Where suitable habitat is present, consider the broader habitat evidence and use careful, staged inspections.

No shelter type or resting site has been identified for T. relictus, including logs, bark, litter, soil cracks or burrows.

Sheltering habitat: Precautionary search areas

In wetter, more heavily forested areas, crews can use general ground-beetle search practice to inspect accessible ground cover and woody debris carefully. This is a precautionary survey approach, not a confirmed shelter association for T. relictus.

Threats: Conservation status

The species is listed as Priority 3, meaning it is poorly known and known from several locations. It is not described as under imminent threat. Specific threats have not been documented.

DBCA lists T. relictus as Priority 3 on its Threatened and Priority Fauna List dated 1 July 2025, in the South West region. Priority 3 is a DBCA priority-list category, not a listing under the Biodiversity Conservation Act 2016. There is no national listing.

Threats: Works-related considerations

No species-specific threats have been identified. As the beetle is poorly known and associated with wetter, more heavily forested environments, avoid unnecessary disturbance to such habitat and treat uncertain records conservatively.

Survey methodology: 1. Desktop assessment

No validated survey protocol, detection period or detectability estimate has been established for T. relictus. A qualified invertebrate ecologist should lead survey design and adapt it to the habitat and project risk.

Review current DBCA and museum records, relevant project reports, and the Atlas of Living Australia record summary. Treat generalised or imprecise points as leads for assessment, not as confirmed occupied habitat.

Survey methodology: 2. Habitat inspection

Map and inspect wetter, more heavily forested parts of the survey area, noting habitat condition and any proposed clearing footprint. Record the methods, locations and effort used so that a non-detection is not mistaken for proof of absence.

Survey methodology: 3. Ground-level search

As general ground-beetle survey practice, a specialist may use careful visual searches and suitable invertebrate sampling methods in ground cover and woody debris. Select methods and any specimen handling with regard to approvals, animal welfare, biosecurity and the need for reliable identification.

Vegetation associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific vegetation association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Ecosystem associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific ecosystem association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Soil and substrate associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific soil association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Water and wetland associations

Source-checked associations and automatically indexed candidates are separated below. An association does not establish site presence, preference or dependence.

No species-specific water association has been indexed or source-checked in this evidence library. This is an evidence gap, not evidence of no association.

Fauna records and mapped habitat: Not yet analysed

Record locations can be overlaid with mapping, but record frequency alone does not measure habitat preference. No species is excluded from desktop assessments by this analysis.

No quality-controlled record-to-map analysis has been completed for this species. The existing generalised distribution dots and indicative range polygons have not been treated as precise occurrence coordinates.

A defensible run needs dated, independently attributable records, coordinate uncertainty, duplicate and captive-record checks, layer versions and regional scope. Preference and absence require additional survey-effort and detection evidence.

Habitat limitations and contrary evidence: No supported exclusion recorded

Not recorded is not the same as cannot occur. Low suitability, resident habitat, breeding habitat and occasional movement are different conclusions.

This library has not established a vegetation, ecosystem or soil-type exclusion for this species. This does not mean all habitat is suitable; the evidence needed to justify an exclusion has not been assembled.

Habitat limitations and contrary evidence: Before using a negative association

  • Confirm the taxon, geographic region, life stage and habitat function covered by the evidence.
  • Check survey methods, season, repeated effort and detectability before interpreting non-detection.
  • Investigate credible contradictory records and microhabitats absent from broad mapping.
  • Do not convert a missing map class, low record count or failed data request into species absence.

Before habitat disturbance: 1. Confirm records and habitat

Before clearing or ground disturbance, use the habitat evidence and uncertainty around records to set proportionate survey and avoidance measures.

Check whether current DBCA or museum records, project reports or new survey results indicate a potential occurrence near the works. Distinguish precise observations from coarse or generalised record points.

Before habitat disturbance: 2. Plan avoidance and controls

Where wetter, more heavily forested habitat overlaps the works area, have a suitably qualified ecologist assess the risk and recommend avoidance or further survey. Mark retained habitat and approved work limits clearly, and brief crews on stop-work and reporting procedures.

During habitat disturbance: 1. Work to marked limits

During works, keep disturbance within approved limits and respond promptly to any ground beetle that may need identification.

Keep machinery and personnel within the approved footprint. Avoid unnecessary damage to retained wetter, more heavily forested habitat and do not move woody debris or other ground cover into retained areas without ecologist direction.

During habitat disturbance: 2. Stop and seek advice

If a potentially relevant beetle is found, pause disturbance in the immediate area where safe to do so. Do not assume it is T. relictus from appearance alone; photograph or collect it only under appropriate direction and approvals, and contact the project ecologist for identification advice.

After habitat disturbance: 1. Record and report

After disturbance, document outcomes and check that agreed habitat controls remain effective. No species-specific translocation or release procedure has been established.

Record any observations, identification results, locations, habitat context and actions taken. Provide relevant records and reports to the project ecologist and, where required, the relevant agency.

After habitat disturbance: 2. Review controls

Inspect work boundaries and retained habitat for unauthorised disturbance. If a confirmed or suspected record is found, seek specialist and regulatory advice before resuming affected works.

Rehabilitation actions: 1. Restore disturbed ground

Rehabilitation should aim to restore suitable native habitat structure and minimise further disturbance, without assuming that this species' recovery requirements are known.

Use locally appropriate native vegetation and site-specific rehabilitation advice to restore disturbed areas adjoining retained forest habitat. Avoid introducing materials or organisms that could create biosecurity risks.

Rehabilitation actions: 2. Protect retained habitat

Prevent repeated access, erosion and avoidable removal of ground cover or woody material from retained areas. Monitor rehabilitation and report any beetle observations to the project ecologist. No species-specific rehabilitation method has been established.

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