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Lord Howe Flax Snail (Placostylus bivaricosus)

The Lord Howe Flax Snail is a large land snail endemic to Lord Howe Island and found in Australia only there. Damp, shaded closed forest with leaf litter on sandy or calcarenite-derived soils is important habitat, including for assessing potential impacts from development.

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

New South Wales, Biodiversity Conservation Act 2016: Endangered.

Seasonal planning

On Lord Howe Island, egg-laying probably occurs in late spring and summer, from November to February.

Seasonal evidence: From published sources for this species.

Timing varies between sites and years.

  • Breeding season: On Lord Howe Island, egg-laying probably occurs in late spring and summer, from November to February.

Identification: Appearance

This is a large, ground-dwelling snail with a pointed shell up to 8 cm long. The shell is medium to dark brown, becoming white with age, and mature animals have a thickened lip; the body is black.

This is a large, ground-dwelling snail with a pointed shell up to 8 cm long. The shell is medium to dark brown, becoming white with age, and mature animals have a thickened lip; the body is black.

Identification: Confirming identity

Confirm the identity of any suspected record with a specialist and a photograph or voucher, as required by the relevant permit.

Distribution: Known range

The species is endemic to Lord Howe Island and Rabbit (Blackburn) Island in its lagoon. Surviving populations are restricted to fragmented locations in the Settlement area and around North Bay on Lord Howe Island.

The species is endemic to Lord Howe Island and Rabbit (Blackburn) Island in its lagoon. Surviving populations are restricted to fragmented locations in the Settlement area and around North Bay on Lord Howe Island.

Distribution: National mapping

The Commonwealth species distribution model (SNES) maps where the species or its habitat is known, likely or may occur. Use it with local records and site inspection.

Habitat: Habitat

It occurs in evergreen closed forest, including Kentia Palm forest and Greybark-Blackbutt forest, often in damp, shaded places with leaf litter. Sites are mostly on calcarenite-derived or sandy soils, and Banyan trees are often nearby.

It occurs in evergreen closed forest, including Kentia Palm forest and Greybark-Blackbutt forest, often in damp, shaded places with leaf litter. Sites are mostly on calcarenite-derived or sandy soils, and Banyan trees are often nearby.

Foraging habitat: Diet

Not documented in the published sources used for this profile.

Not documented in the published sources used for this profile.

Breeding habitat: Breeding

Not documented in the published sources used for this profile.

Not documented in the published sources used for this profile.

Sheltering habitat: Shelter

The snail shelters under leaf litter on the forest floor, usually beneath canopy cover in damp, shady locations. It is often found near Banyan trees, though not exclusively.

The snail shelters under leaf litter on the forest floor, usually beneath canopy cover in damp, shady locations. It is often found near Banyan trees, though not exclusively.

Threats: Threats

Habitat clearing and modification for development threaten the species. Exotic animals, particularly Black Rats, prey on snails and disturb their habitat; other reported threats include predatory birds, domestic stock and poultry, and habitat disturbance.

Habitat clearing and modification for development threaten the species. Exotic animals, particularly Black Rats, prey on snails and disturb their habitat; other reported threats include predatory birds, domestic stock and poultry, and habitat disturbance.

Threats: Works risk

Clearing or modifying closed-forest habitat for development can remove or disturb habitat used by the snail, particularly forest with leaf litter on sandy or calcarenite-derived soils. Other construction or operational impacts are not described in the available information.

Survey methodology: 1. Species-specific methods

Use methods consistent with the Commonwealth survey guidelines and engage a specialist with the right permits.

Surveys in 1999 recorded live snails at 19 sites, fresh specimens at 9 sites, and old shells only at 26 localities.

Survey methodology: 2. Commonwealth guidance

For EPBC Act referrals, survey effort and methods should be consistent with the on-ground surveys and data for referred actions under the EPBC Act, read with the Significant impact guidelines 1.1.

Survey methodology: 3. Limits

A non-detection is not proof of absence. Match survey timing to the species and season, and record effort.

Vegetation associations: Rainforest or vine thicket

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

It occurs in evergreen closed forest, including Kentia Palm forest and Greybark-Blackbutt forest, often in damp, shaded places with leaf litter.

Automatically indexed from existing profile text. Not a verified preference, mapped occurrence or habitat requirement. Check the original source and regional qualifiers before use.

Evidence: Unreviewed profile-derived candidate

Confidence: Not independently verified

Region: Scope as described in the quoted profile text; not independently verified. Profile states: NSW.

Habitat use: general

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: Sandy soils or sand

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

Sites are mostly on calcarenite-derived or sandy soils, and Banyan trees are often nearby.

Automatically indexed from existing profile text. Not a verified preference, mapped occurrence or habitat requirement. Check the original source and regional qualifiers before use.

Evidence: Unreviewed profile-derived candidate

Confidence: Not independently verified

Region: Scope as described in the quoted profile text; not independently verified. Profile states: NSW.

Habitat use: general

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 disturbance: 1. Desktop and approvals

Confirm whether the project could affect the species before works begin.

Check national mapping, state records and recent surveys for the site. An action likely to have a significant impact on this nationally listed species needs EPBC Act referral, and state permits apply where it is state listed.

Before disturbance: 2. Plan to avoid

Design the footprint, timing and access to avoid known or likely habitat, and brief crews on what to look for and who to call.

During disturbance: 1. Controls

Keep works inside the approved footprint and conditions.

Fence or mark habitat to be retained and keep machinery, stockpiles and spoil out of it.

During disturbance: 2. Stop and report

If the species is found unexpectedly, stop work at that spot and contact the project ecologist and the relevant agency.

After disturbance: 1. Records

Record outcomes.

Record sightings, habitat lost or retained and any injury or death, and report them under the approval conditions.

Rehabilitation: 1. Restore

Restore disturbed habitat where possible.

Reinstate disturbed ground with local species, return logs, rocks and litter, and control weeds and erosion until the site is stable.

Sources