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Theda Station Camaenid Land Snail (Torresitrachia thedana)

The Theda Station Camaenid Land Snail is an air-breathing terrestrial snail in the family Camaenidae. It is known from a small number of Kimberley records, but its habitat and ecology are poorly documented. It is DBCA Priority 1 in Western Australia, so works in or near its known range warrant careful survey and precautionary management.

Conservation status

Western Australia, WA Threatened and Priority Fauna List: Priority 1.

Seasonal planning

Seasonal activity and breeding information are unknown. Use the entries below as a planning window only, not as evidence of species phenology.

Seasonal knowledge: No species-specific active, inactive, breeding or movement months are recorded.

The season row is a general planning prompt only; it does not indicate recorded activity for T. thedana.

  • Survey and work planning: All-year planning window only. Species activity and seasonal detectability are unknown, so do not assume any period is free of risk.

Identification: Appearance and size

Species-specific identification information is very limited. Treat shell characters as clues for checking, not as a confirmed field diagnosis.

The species is an air-breathing terrestrial snail in the family Camaenidae. Its shell description, colour and size have not been documented.

The genus Torresitrachia is described as having small to medium-sized, discoidal shells, a loosely coiling umbilicus and a brownish colour, with radial ribs or periostracal hairs. These genus-level traits have not been confirmed individually for T. thedana.

Identification: Similar species

Other Torresitrachia species occur in Australia, but diagnostic differences between them and T. thedana have not been documented. A general shell resemblance alone is not enough to identify this species.

Identification: Field signs

Species-specific field signs and survey detectability have not been documented. As general land-snail practice, record any shells or live snails found, photograph them in place where possible, and seek expert identification rather than relying on shell appearance alone.

Distribution: Known range

Available records indicate a restricted and poorly documented Western Australian distribution.

The species is endemic to Australia. Atlas of Living Australia records show three Western Australian records at three distinct 0.1-degree locations, around latitude 14.8°S and longitude 126.3°E to 126.6°E. Records outside Western Australia were excluded as likely errors.

Distribution: Western Australian region

The DBCA list identifies the Kimberley region. The common name refers to Theda Station, but no precise locality or coordinates are available for a confirmed record there.

Habitat: Habitat knowledge

The species’ habitat has not been documented, so habitat suitability at a development site cannot be inferred from the known records alone.

No vegetation type, landform, soil, elevation or site-level habitat is recorded for T. thedana. The known regional context is the Kimberley.

Habitat: Site assessment

Do not assume a site is unsuitable because it lacks a particular habitat feature. Assess the full disturbance footprint and nearby undisturbed ground, and document the ground conditions and cover features present.

Foraging habitat: Diet

The species’ diet and feeding locations have not been documented.

Food plants and feeding behaviour have not been documented for T. thedana.

Foraging habitat: Field precautions

As a general precaution for land-snail surveys, inspect the ground and any natural cover features present without assuming that particular plants or substrates are food or feeding habitat for this species.

Breeding habitat: Breeding information

Breeding biology and breeding habitat are poorly known.

No breeding season, egg-laying site, clutch size, development or juvenile information is recorded for T. thedana.

Breeding habitat: Precaution

Do not schedule works on the assumption that there is a known safe season. Apply survey and avoidance measures whenever suitable land-snail survey conditions and site access allow.

Sheltering habitat: Shelter knowledge

The species’ sheltering behaviour and shelter sites have not been documented.

It is not known whether this species shelters in leaf litter, beneath rocks or logs, in crevices, or elsewhere.

Sheltering habitat: General search approach

As general land-snail survey practice, carefully inspect natural cover features within the survey area. Replace any items moved during inspection and avoid unnecessary disturbance to the ground.

Threats: Threat information

No threats specific to T. thedana have been identified.

The species is poorly known and recorded from few locations, with none on conservation lands.

Threats: Work-site risks

As a general precaution for terrestrial snails, clearing, vehicle movement and ground disturbance could directly affect individuals or their immediate surroundings. These are potential work-site pathways, not documented threats specific to this species.

Survey methodology: 1. Desktop assessment

Species-specific survey methods and detectability have not been documented. Use a cautious, documented land-snail search approach.

Check current DBCA priority fauna information, available records and project mapping. The few known records should not be treated as defining the full distribution.

Survey methodology: 2. Ground search

As general land-snail practice, search the proposed disturbance footprint and adjoining areas systematically. Inspect the ground surface and natural cover features present, taking care not to damage or remove them unnecessarily.

Survey methodology: 3. Record and verify

Record search locations, effort, conditions and the features examined. Photograph live animals and shells in place where possible. As there is no confirmed species-level field diagnosis, refer uncertain material to a suitably qualified expert.

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. Plan the footprint

Plan works around uncertainty in the species’ distribution, habitat and detectability.

Confirm whether works are in the Kimberley and near the broad area indicated by known records. Minimise the disturbance footprint and avoid unnecessary ground disturbance.

Before habitat disturbance: 2. Survey and brief crews

Arrange a targeted land-snail search before clearing where the risk assessment indicates it is warranted. Brief spotter catchers and crews that the species is poorly known and that shells or live snails requiring identification should be reported promptly.

Before habitat disturbance: 3. Set precautions

Agree on a stop-work and notification process for suspected animals or shells. Mark any retained areas and communicate access limits to all personnel.

During habitat disturbance: 1. Control clearing

Use staged, controlled work and respond cautiously to any possible land-snail finds.

Keep machinery within approved limits and avoid unnecessary movement of rocks, logs or other natural cover features. Have the spotter catcher check the active work area as disturbance proceeds.

During habitat disturbance: 2. Respond to a find

If a live snail or potentially relevant shell is found, pause work in the immediate area, prevent further disturbance and notify the environmental lead. Photograph and record the find before any handling or relocation is considered.

During habitat disturbance: 3. Follow approvals

Do not collect or relocate animals unless this is authorised and directed by an appropriately qualified person under the relevant approvals and procedures.

After habitat disturbance: 1. Review records

Keep records of searches, finds and disturbance, and use them to inform follow-up decisions.

Compile survey effort, observations, photographs and mapped disturbance areas. Submit identification queries to an appropriate specialist and retain the response with project records.

After habitat disturbance: 2. Check retained areas

Where areas have been retained as a precaution, check that they remain clearly marked and have not been disturbed by access, storage or follow-on works.

Rehabilitation actions: 1. Restore the site

Species-specific rehabilitation requirements have not been documented. Focus on restoring disturbed ground and avoiding further impacts.

Rehabilitate disturbed areas in line with project approvals and site rehabilitation plans. Avoid introducing unverified soil, plant material or other materials that could create additional ecological risks.

Rehabilitation actions: 2. Monitor outcomes

Document rehabilitation actions and any subsequent observations of land snails. Do not treat general vegetation establishment as evidence that habitat for T. thedana has been restored, because its habitat requirements have not been documented.

Sources