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Mystical Pygmy Trapdoor Spider (Bertmainius mysticus)

The mystical pygmy trapdoor spider is a Western Australian mygalomorph spider in the family Migidae, described from south-western Australia. It is recorded from a small area in the Warren region and is poorly known, so works near suitable habitat should use cautious survey and clearing procedures. Its Western Australian status is DBCA Priority 2.

Conservation status

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

Seasonal planning

Seasonal activity, breeding and movement are not documented. Treat the following as a general planning window only, not a species-specific activity calendar.

Seasonal activity: Not documented.

Breeding period: Not documented.

No species-specific months are available.

  • Cautious survey and work planning: Planning window only. No season is established as a low-risk period; use suitable checks and precautions whenever works may affect potential habitat.

Identification: Appearance and size

Taxonomic information is available, but the species has no published field description or diagnostic characters.

Bertmainius mysticus is a spider in the family Migidae. Its appearance, body measurements and distinguishing field marks have not been documented.

  • Do not identify the species from size, colour or a presumed burrow form without a reliable identification.

Identification: Similar species

Other Bertmainius species occur in Western Australia, but field characters that distinguish them from B. mysticus are not documented. Record uncertain specimens or signs as an unidentified trapdoor spider and seek expert advice.

Identification: Field signs

Species-specific field signs and survey detectability are unknown. As general practice for trapdoor spiders, look carefully for possible burrow openings or doors in suitable ground, but do not treat an unconfirmed sign as evidence of this species.

Distribution: Known range

Records place the species in a restricted part of south-western Western Australia. The known records are sparse and do not define its complete range.

The species is recorded from south-western Australia, including Keystone State Forest and Walpole-Nornalup National Park. Atlas of Living Australia records show 32 Western Australian records at three distinct 0.1-degree locations, between latitudes -35 and -35 and longitudes 116.6 and 116.8.

Distribution: WA listing region

The DBCA Priority Fauna List identifies the Warren region for this species. Its occurrence throughout the region has not been established, and a complete distribution boundary is not available.

Distribution: Range uncertainty

The species is listed as Priority 2 and is poorly known, with records from few locations, some on conservation lands. No national listing is given.

Habitat: Regional setting

The species’ precise site requirements are unknown.

A study of the genus Bertmainius reports that it is endemic to the mesic zone of south-western Australia. This is genus-level context, not a detailed habitat description for B. mysticus.

Habitat: Recorded places

Species records include a state forest and a national park. The vegetation, soil, slope, moisture conditions and other microhabitat features used by this species at those places are unknown.

Foraging habitat: Known information

The species’ feeding ecology and foraging habitat are unknown.

Its diet, prey, foraging behaviour and feeding locations have not been documented.

Foraging habitat: Precaution on site

As a general precaution for an invertebrate with poorly known ecology, avoid disturbing ground features around possible shelter signs and retain undisturbed habitat where practicable. Do not infer prey or foraging requirements from the species name or family.

Breeding habitat: Known information

Breeding biology and breeding habitat are poorly known.

The breeding season, egg or brood details, juvenile development and breeding-site characteristics have not been documented.

Breeding habitat: Work planning

Do not assume that any particular season is free of breeding activity. Where works could affect potential habitat, use the same cautious checks and avoidance measures throughout the year unless reliable species-specific information becomes available.

Sheltering habitat: Known information

The species’ shelter and burrow structure have not been documented.

The species is a trapdoor spider, but its shelter sites, burrow dimensions, doors and shelter placement are unknown.

Sheltering habitat: General field precaution

When checking for trapdoor spiders, inspect the ground surface carefully and avoid probing, scraping or opening possible burrows. A suspected burrow is not a confirmed record of this species.

Threats: Reported pressures

A study of Bertmainius species identifies broad pressures but does not detail site-specific threats to this species.

A 2015 taxonomic study considered all seven species it discussed to be threatened under IUCN criteria and identified inappropriate fire regimes and climate change as major threatening processes. This is not a formal national listing for B. mysticus.

Threats: Works-related risk

The effects of particular development activities on this species have not been assessed. As a precaution, avoid unnecessary ground disturbance in potential habitat and follow the project’s approved fauna and clearing procedures.

Threats: Status

The species is DBCA Priority 2 in Western Australia. This is a DBCA priority category, not a listing under the Biodiversity Conservation Act 2016. No national listing is given.

Survey methodology: 1. Desktop assessment

Species-specific survey methods and detectability are unknown. Use cautious surveys and do not rely on a single sign or method.

Check current DBCA information, project records and available spatial data for known records and the Warren region. Known records include Keystone State Forest and Walpole-Nornalup National Park. Sparse records do not demonstrate absence elsewhere.

Survey methodology: 2. Ground inspection

As general practice for trapdoor spiders, have a suitably experienced observer inspect the ground surface in potential habitat for possible burrow signs. Work slowly, avoid damaging the surface, and do not excavate or open suspected burrows.

Survey methodology: 3. Record and escalate

Record the location, date, observer, habitat context and clear photographs of any suspected signs, without disturbing them. Seek expert identification and follow relevant DBCA and project reporting requirements. A non-detection should not be treated as proof of absence.

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 and constraints

Plan works on the basis that this poorly known species may be difficult to detect and that local records are limited.

Review DBCA priority fauna information, available survey records and known Warren region records before finalising clearing limits. Confirm the project’s approval conditions and fauna management procedures.

Before habitat disturbance: 2. Inspect potential habitat

Arrange a careful pre-clearance inspection by a suitably experienced fauna spotter catcher or ecologist. As general practice for trapdoor spiders, check the ground surface for possible burrow signs without probing or excavating.

Before habitat disturbance: 3. Set out avoidance measures

Clearly mark approved clearing boundaries and areas to be retained. Brief crews on the possibility of an unidentified trapdoor spider or burrow sign and on the stop-work and escalation process.

During habitat disturbance: 1. Maintain controls

Use careful, staged work practices and respond conservatively to any suspected spider or shelter sign.

Keep machinery and personnel within approved work areas. Avoid unnecessary scraping, tracking or storage of materials on retained ground.

During habitat disturbance: 2. Stop and assess

If a suspected spider or possible burrow is found, pause work in the immediate area, prevent further disturbance and contact the project ecologist or fauna lead. Do not handle, destroy or open the suspected shelter.

During habitat disturbance: 3. Document and follow advice

Record the observation and its location, using photographs only where this can be done without disturbance. Obtain an appropriate identification and follow project approvals and relevant agency advice before work resumes.

After habitat disturbance: 1. Check the work area

After works, document outcomes and retain any undisturbed areas identified as potential habitat.

As general fauna practice, have the responsible environmental representative check the cleared area and retained boundaries for overlooked fauna or signs, where safe and consistent with approvals. Do not excavate possible burrows.

After habitat disturbance: 2. Report records

Document any confirmed or suspected observations, the response taken and the final work outcome. Submit records through the project’s required reporting channels and seek expert review where identification is uncertain.

Rehabilitation actions: 1. Protect retained areas

Species-specific rehabilitation requirements are unknown. Rehabilitation should avoid further disturbance to retained ground.

Keep rehabilitation activities within approved boundaries and avoid unnecessary soil disturbance in retained potential habitat. Follow the project’s approved rehabilitation plan.

Rehabilitation actions: 2. Monitor and adapt

Record rehabilitation actions and any relevant fauna observations. Do not claim habitat suitability or successful establishment for this species without supporting assessment, as its specific habitat requirements are unknown.

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