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Mortlock River Shield-backed Trapdoor Spider (Idiosoma schoknechtorum)

The Mortlock River shield-backed trapdoor spider is a Western Australian shield-backed trapdoor spider in the genus Idiosoma. Records place it in the Wheatbelt, but its precise habitat and ecology are poorly documented. It is listed as DBCA Priority 3 in WA.

Conservation status

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

Seasonal planning

Species-specific activity and breeding months are not known. Use year-round survey and avoidance planning rather than assuming a low-risk season.

Species-specific timing: Not documented.

Planning approach: Treat all months as potentially relevant when scheduling searches and works.

No seasonal pattern for Idiosoma schoknechtorum has been established.

  • Survey and works planning: Year-round planning window only; species-specific activity and breeding periods are not known.

Identification: Appearance and size

Identification information for this species is limited. Seek expert confirmation where identification may affect a clearing decision.

The species is a shield-backed trapdoor spider in the genus Idiosoma and the nigrum-group. Its size and species-specific appearance have not been documented.

The group has enlarged, hardened abdominal structures associated with its shield-backed appearance and defence. These group-level features are not sufficient for a complete identification.

Identification: Similar species

Idiosoma schoknechtorum is closely related to I. nigrum. Simple field characters for distinguishing them or other Idiosoma species have not been documented.

Identification: Field signs

Shield-backed trapdoor spiders as a group are described as having burrows with twigs arranged in a moustache-like pattern at the entrance. This may be a useful search cue, but it is not confirmed as diagnostic for this species.

Distribution: Known range

Records indicate a limited known range in south-western WA, but do not establish the species' full distribution.

Atlas of Living Australia records comprise 27 WA records at 17 distinct 0.1-degree locations, between latitude -32.4 and -31.5 and longitude 116.3 and 117.5. Records outside WA were excluded as likely errors.

A published caption identifies the species as found in the Wheatbelt. Precise collection sites have not been named.

Distribution: WA regions and records

No DBCA regions are specified for this species on the WA priority list. Its Wheatbelt record does not establish presence in any particular DBCA region.

Distribution: Range limits

The plotted record extent is not a confirmed range boundary. The species is poorly known, and its dispersal and population connectivity have not been described.

Habitat: Available habitat context

The species' habitat requirements have not been documented.

Shield-backed trapdoor spiders as a group are described as restricted to patches of remnant vegetation. This is group-level context, not a confirmed habitat description for I. schoknechtorum.

Habitat: Site assessment

Do not assume a site is unsuitable because it differs from this limited group-level description. Record vegetation, soils, ground cover and nearby remnant vegetation during site assessments, and seek advice where burrow-like signs are present.

Foraging habitat: Diet and activity

The species' feeding behaviour and foraging habitat have not been documented.

What I. schoknechtorum eats, where it forages and when it is active are not known. Shield-backed trapdoor spiders are generally described as predators, but prey details for this species are not known.

Foraging habitat: Precaution

When searching, inspect the ground and burrow entrances carefully without disturbing possible shelters. Do not infer the spider's absence from a lack of visible foraging activity.

Breeding habitat: Known information

Breeding sites, timing and reproductive details for this species are not known.

Information on mating, egg laying, young and breeding habitat is not available. Do not apply timing or reproductive details from other Idiosoma species to this one.

Breeding habitat: Site precautions

Treat occupied or suspected burrows as potential shelter and breeding sites during works planning. Avoid unnecessary disturbance while the species' breeding ecology remains unknown.

Sheltering habitat: Burrow context

The species' sheltering ecology is not documented, although group-level burrow information offers a cautious search cue.

Shield-backed trapdoor spiders as a group are described as having burrows with twigs arranged around the entrance in a moustache-like pattern. Hardened abdominal structures used in defence are also described across the group. These details are not a complete species-specific account.

Sheltering habitat: Finding possible shelters

As general trapdoor-spider search practice, scan the ground closely for small burrow entrances and attached material. Do not probe, open or block suspected burrows during routine surveys.

Threats: Status and knowledge

The species' specific threats have not been established.

The species is listed as DBCA Priority 3, meaning it is poorly known, known from several locations and not under imminent threat. This is a DBCA priority category, not a listing under the Biodiversity Conservation Act 2016.

No national listing is given. Species-specific threatening processes have not been identified.

Threats: Development context

Shield-backed trapdoor spiders as a group are described as restricted to remnant vegetation, and clearing has affected important habitat for some species in the group. This does not establish a species-specific threat assessment for I. schoknechtorum.

As a precaution, assess proposed clearing for burrows and remnant vegetation, and avoid disturbance to confirmed or suspected individuals where practicable.

Survey methodology: 1. Desktop assessment

The species is poorly known, and no validated survey method has been established. Use cautious ground searches and document uncertainty.

Review available records, the WA priority status, proposed disturbance boundaries and nearby retained vegetation. Atlas of Living Australia records indicate 17 distinct 0.1-degree locations, not exact burrow positions.

Survey methodology: 2. Ground search

As general practice for trapdoor spiders, search slowly on foot and inspect the ground for burrow entrances and attached twigs. Give particular attention to remnant vegetation, while noting that the species' specific habitat is unknown.

Survey methodology: 3. Record and verify

Map suspected burrows with coordinates, photographs and brief habitat notes. Do not identify the species from a burrow cue alone. Arrange expert verification where records may affect works.

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. Review records

Plan surveys and avoidance measures before clearing, allowing for uncertainty in the species' habitat and detectability.

Check current project records and relevant fauna databases, and consult a suitably experienced arachnologist if the species may occur. Treat the broad Atlas extent as a guide to the known record area, not a site-level prediction.

Before habitat disturbance: 2. Survey the footprint

Have a qualified fauna spotter or ecologist conduct a careful ground search of the disturbance footprint and areas that may be indirectly affected. Include nearby remnant vegetation where it can inform avoidance planning.

Before habitat disturbance: 3. Set out controls

Mark confirmed or suspected burrows and establish practical no-go areas before machinery enters. Brief clearing crews on search cues, the reporting process and the requirement to stop work if a suspected spider or burrow is found.

During habitat disturbance: 1. Maintain controls

Use staged, supervised work and respond cautiously to burrows or spiders encountered during disturbance.

Keep machinery and personnel out of marked avoidance areas. Maintain clear communication between the spotter, ecologist and equipment operators.

During habitat disturbance: 2. Stop and check

If a suspected burrow or spider is found, stop work in the immediate area and prevent further disturbance. Notify the fauna spotter or ecologist for assessment and identification.

During habitat disturbance: 3. Avoid handling

Do not excavate, probe or relocate a suspected burrow as a routine response. Consider handling or relocation only under appropriate approvals and with specialist direction.

After habitat disturbance: 1. Update records

After works, document findings and check that agreed avoidance measures remain effective.

Record sightings, suspected burrows, search effort, identification confidence and any disturbance. Submit verified records through the appropriate project and agency reporting channels.

After habitat disturbance: 2. Review controls

Check that retained areas and marked avoidance zones have not been disturbed. Report any accidental impacts promptly and follow the project's incident and approval requirements.

Rehabilitation actions: 1. Protect retained areas

No species-specific rehabilitation requirements are known. Prioritise protection of retained habitat and do not assume rehabilitation will replace occupied burrow habitat.

Prevent unnecessary traffic, soil disturbance and material storage in retained vegetation and around known or suspected burrows.

Rehabilitation actions: 2. Restore disturbed ground

Where rehabilitation is required, use the site's approved methods and locally appropriate vegetation objectives. Whether restored areas will provide suitable habitat for this spider is unknown.

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