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Wilson's Camaenid Land Snail (Prince Regent) (Hadra wilsoni)

Wilson's camaenid land snail is a terrestrial land snail now placed in Youwanjela, endemic to the Kimberley of Western Australia. Its records are concentrated in a small part of the region, while its habitat and ecology are poorly documented, so works near potential records warrant careful checks and a precautionary approach. It is listed as DBCA Priority 2 in Western Australia, a DBCA priority category rather than a listing under the Biodiversity Conservation Act 2016.

Conservation status

Western Australia, WA Threatened and Priority Fauna List: Priority 2.

Seasonal planning

Seasonal activity, breeding and survey timing have not been documented. Plan precautionary checks year-round rather than treating any period as confirmed inactive.

Species-specific timing: Not documented.

Planning approach: The activity row is a general planning window, not a claim about seasonal activity.

No species-specific seasonal information is available. Do not infer that the snail is absent or inactive at any time of year.

  • Precautionary survey and works checks: Year-round planning window only. Species activity and detectability by season are unknown.

Identification: Appearance and size

Use the shell description as a guide, but do not rely on appearance alone to confirm an identification.

The shell is described as comparatively large, thin, broadly subglobose and almost uniform brown. No measurements, other external features or colour variation have been documented.

Identification: Similar species and field signs

No similar species or distinguishing field signs have been documented. The species was originally described in Hadra, but was placed in the new genus Youwanjela following study of shell and genital features and molecular data.

As general land-snail survey practice, record live snails and shells separately and photograph specimens in place. A shell alone may not allow a reliable field identification.

Distribution: Known range

The known range is in the Kimberley of Western Australia, with the named type locality at Prince Regent Nature Reserve.

The species is endemic to Western Australia and is described as an endemic camaenid of the Kimberley. The type locality is the valley of Youwanjela Creek, Prince Regent Nature Reserve, in the north-western Kimberley.

Distribution: Records and region

Atlas of Living Australia records show 15 Western Australian records at four distinct 0.1-degree locations, between latitude -15.6 and -15.5 and longitude 125.3 and 125.5, under the name Youwanjela wilsoni. Records outside Western Australia were excluded from that summary as likely errors.

The WA priority list flags the Kimberley region. The available records do not establish occupancy throughout the region or beyond the reported locations.

Habitat: Documented setting

The type locality is known, but the snail's habitat requirements are poorly documented.

Topotypic material was examined from the valley of Youwanjela Creek in Prince Regent Nature Reserve. The vegetation, landform, substrate and moisture conditions used by the species have not been documented.

Habitat: Habitat uncertainty

The creek valley description does not mean the snail is aquatic or restricted to creek margins. Its particular habitat associations have not been documented.

Foraging habitat: Diet

Diet and feeding locations have not been documented.

Food plants and other food sources have not been documented.

Foraging habitat: Foraging areas

Where and when Wilson's camaenid land snail forages is unknown. Avoid assigning a foraging habitat from the type locality alone.

Breeding habitat: Breeding information

Breeding habitat and reproductive timing are poorly known.

Breeding sites, reproductive behaviour, egg or clutch details, and breeding months have not been documented.

Breeding habitat: Precaution

Do not use an assumed breeding season to rule out impacts. Treat potential habitat as relevant year-round unless site-specific evidence supports a different approach.

Sheltering habitat: Shelter information

Sheltering behaviour and responses to dry conditions are poorly known.

Sheltering places and behaviour, including any use of vegetation, rocks, litter or crevices, have not been documented.

Sheltering habitat: Search implications

As general land-snail survey practice, examine suitable ground-level refuges carefully where present, without assuming that the species uses any particular refuge type.

Threats: Known pressures

Threats specific to Wilson's camaenid land snail have not been documented.

No species-specific threats, population trend or impact assessment have been documented. Its DBCA Priority 2 status reflects that it is poorly known and known from few locations, with some locations on conservation lands.

Threats: Works-related caution

As a general precaution for terrestrial land snails, avoid unnecessary crushing, handling and disturbance of ground-level habitat during works. These are precautionary measures, not documented species-specific threats.

Survey methodology: 1. Desktop assessment

Survey design should account for limited species-specific information and the absence of documented seasonal activity or habitat preferences.

Check project coordinates against the known Kimberley range and the Atlas of Living Australia records summary. Treat records as a guide to where to investigate, not as a complete distribution map.

Survey methodology: 2. Field inspection

As general land-snail survey practice, inspect ground-level refuges and search for live snails and shells in areas that may be disturbed. A survey method, best conditions, detectability and seasonal window have not been established for this species.

Photograph observations in place, record coordinates and micro-site details, and seek expert confirmation for uncertain identifications. Do not collect specimens unless authorised.

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 the work area

Plan checks around the known range and acknowledge that habitat requirements are poorly documented.

Review available records and determine whether the development site lies near the reported Kimberley locations. Arrange a suitably timed fauna assessment before clearing where records or uncertainty warrant it. No species-specific survey season is known.

Before habitat disturbance: 2. Brief the crew

Explain the species' Priority 2 status, the limits of current knowledge and the stop-work process for a suspected snail or shell. Mark agreed no-go areas and avoid unnecessary ground disturbance before survey results are reviewed.

During habitat disturbance: 1. Work to agreed limits

Use cautious work practices and respond promptly to any possible observation.

Keep clearing and vehicle movements within approved boundaries. As a general land-snail precaution, minimise crushing and avoid disturbing ground-level refuges outside the required footprint.

During habitat disturbance: 2. Respond to finds

If a possible individual or shell is found, pause work in the immediate area, prevent further disturbance and notify the site ecologist or fauna spotter catcher. Photograph and record the location. Identification and any handling or relocation should follow the project approval and advice from an appropriately qualified person.

After habitat disturbance: 1. Record and report

Document outcomes and check that work boundaries and response procedures were followed.

Keep records of survey effort, conditions, search locations, observations and identification confidence. Report confirmed or suspected records through the project's required channels and seek expert review where needed.

After habitat disturbance: 2. Review controls

Check that disturbed areas did not extend beyond the approved footprint and that any exclusion areas remain intact. No species-specific post-disturbance monitoring protocol has been established.

Rehabilitation actions: 1. Restore the work area

Rehabilitation should account for the limited information about this species' habitat features.

Reinstate disturbed areas in line with the project rehabilitation plan and retain or restore local ground-level features where this is compatible with approved works. Avoid describing any feature as essential habitat for this species without supporting evidence.

Rehabilitation actions: 2. Check recovery

Record rehabilitation actions and any subsequent snail observations. Specific restoration targets or monitoring methods for Wilson's camaenid land snail have not been established.

Sources