Idioctis species
Intertidal Trapdoor Spiders Identification in Australia
Coastal Idioctis trapdoor spiders occupy retreats in the tidal zone. A shore location is essential to this comparison.
Avoid handling; bite effects uncertainAbout Intertidal trapdoor spiders
Idioctis is a genus of mygalomorph spiders in Barychelidae. In Australia, I. yerlata is associated with the Queensland coast, while other records involve offshore islands. These spiders are unusual because their retreats can occur where seawater reaches them. They occupy protected cavities or burrows, closing an entrance door when submerged.
Use an intertidal setting, a compact mygalomorph body and a sheltered retreat together. A spider on an ordinary inland rock is not evidence of Idioctis. Nor is every spider beside salt water a trapdoor spider: Desis intertidal spiders belong to a different family and have a different body plan. The genus includes more than one species, so this guide deliberately stops at Idioctis. Photograph a visible animal and its shoreline setting from a safe distance. Leave doors, coral rubble and mangrove roots intact; opening a retreat destroys an important identification clue as well as shelter.
Identification limit: this guide is a comparison aid. A name match in the identifier does not establish a species record.
Compare similar spiders
Sources and further reading
- Churchill and Raven: systematics of intertidal Idioctis
- Australian spider identification key: Idioctis
- Healthdirect: spider-bite first aid
Reviewed 21 September 2026. Identification guide; not a confirmed species diagnosis.
Quick identification
- Tidal shore or mangrove setting
- Stocky mygalomorph body
- Protected silk-lined retreat with a closing entrance
- Not the same group as Desis marine spiders
What to check next
Photograph the whole spider and its surroundings without disturbing it. Use the clues together; a close match is not a confirmed species identification.
When to seek medical help
Do not handle or probe the retreat. If a bite could be from a funnel-web or mouse spider, call 000 and follow pressure-immobilisation first aid. Do not wait for identification. Poisons advice: 13 11 26.
Where it is usually seen
Tidal coastal habitats, including Queensland mangroves and sheltered rock or coral cavities. Offshore records should be checked against the individual species.