Sidymella trapezia
Trapezoid Crab Spider Identification Australia
Small square-ended crab spider found on foliage, bark and garden plants, with long front legs and a trapezoid body outline.
First aid / what to do now
- Move away from the spider and avoid handling it.
- Wash the bite area with soap and water.
- Use a cold pack for pain or swelling.
- Call 13 11 26 or seek medical advice if symptoms are severe, spreading, infected-looking, allergic, or you are unsure what bit you.
This site cannot diagnose a bite. In an emergency call 000. For poisoning advice in Australia call 13 11 26.
How to identify the Trapezoid crab spider / trapezium crab spider
- Small crab-spider shape on foliage, bark or garden surfaces
- Front legs longer and held out to the sides
- Squared or trapezoid abdomen rather than a round orb-weaver body
- Sits still to ambush insects instead of using a capture web
Danger level
Usually low risk
What to check next
Check for the crab-like stance, long front legs and squared body outline. Compare with red-tipped square-ended crab spiders if the abdomen has red humps, and with flower crab spiders if it was on a blossom.
When to seek medical help
This spider is not usually considered dangerous. Seek medical advice for severe pain, allergic symptoms, infection signs, spreading symptoms or uncertainty after any bite.
Where the Trapezoid crab spider / trapezium crab spider is usually seen in Australia
Garden foliage, shrubs, bark, native vegetation, leaves and low plants across Australia, where small insects pass close enough for ambush hunting.
How it differs from lookalikes
These comparisons are clues, not a confirmed species ID. Use several features together: body shape, size, location, web type and behaviour.
- Red-tipped square-ended crab spiderMay overlap because of same region, similar size, similar colour. For this spider, check: Check for the crab-like stance, long front legs and squared body outline. Compare with red-tipped square-ended crab spiders if the abdomen has red humps, and with flower crab spiders if it was on a blossom. For the other possibility, check: Check whether it was sitting still on foliage, especially Dianella-like strappy leaves, with long front legs held crab-style. Compare with flower crab spiders and small jumping spiders if the photo is not close enough.
- Giant bark jumping spiderMay overlap because of same region, similar size, similar colour. For this spider, check: Check for the crab-like stance, long front legs and squared body outline. Compare with red-tipped square-ended crab spiders if the abdomen has red humps, and with flower crab spiders if it was on a blossom. For the other possibility, check: Check for the jumping-spider stance, short stalking movements and bark or wall setting. Compare with generic jumping spiders, peacock spiders and tiny wall spiders if the photo is unclear.
- Knobbly crab spiderMay overlap because of same region, similar size, similar colour. For this spider, check: Check for the crab-like stance, long front legs and squared body outline. Compare with red-tipped square-ended crab spiders if the abdomen has red humps, and with flower crab spiders if it was on a blossom. For the other possibility, check: Check for the crab-like stance, lumpy bark camouflage and no capture web. Compare with trapezoid crab spiders, flower crab spiders and small jumping spiders if the photo is not close enough.
Common comparisons
People often compare this spider with similar Australian spiders. These quick links help you check the closest alternatives.
Compare this spider by state
Use the state guides to compare this spider with other local possibilities.
Similar spiders to compare
Compare this spider with these likely lookalikes before settling on an identification.
Red-tipped square-ended crab spiderUsually low risksame region, similar size, similar colour
Giant bark jumping spiderUsually low risksame region, similar size, similar colour
Knobbly crab spiderUsually low risksame region, similar size, similar colour
Flower spider / crab spiderUsually low risksame region, similar size, similar colourNext useful checks
Still trying to identify this spider?
Use these quick paths if the Trapezoid crab spider / trapezium crab spider is only one possible match. They help compare photo clues, local spider pages, bite guidance and similar Australian spiders.
Reference notes
How this guide stays cautious
Spider Identifier Australia uses visible clues to suggest likely possibilities. It is not a medical diagnosis or a formal species determination.
- Australian Museum spider informationAustralian spider identification, biology and dangerous spider context.
- Australian Museum funnel-web spidersFunnel-web range, identification and bite-safety context.
- Poisons Information CentreCall 13 11 26 for poisons advice from anywhere in Australia.
Common questions
Trapezoid crab spider / trapezium crab spider FAQ
Is the Trapezoid crab spider / trapezium crab spider dangerous?
Danger level: Usually low risk. This spider is not usually considered dangerous. Seek medical advice for severe pain, allergic symptoms, infection signs, spreading symptoms or uncertainty after any bite.
How do I identify the Trapezoid crab spider / trapezium crab spider?
Check the visible body shape, size, colour, markings, location and web or hiding place. Key clues include: Small crab-spider shape on foliage, bark or garden surfaces; Front legs longer and held out to the sides; Squared or trapezoid abdomen rather than a round orb-weaver body; Sits still to ambush insects instead of using a capture web.
What should I do if I think I was bitten by a Trapezoid crab spider / trapezium crab spider?
Clean the area, use a cold pack for pain, and seek medical advice if pain is severe, symptoms spread, infection signs appear, or you are unsure what bit you.
Where is the Trapezoid crab spider / trapezium crab spider usually found?
Garden foliage, shrubs, bark, native vegetation, leaves and low plants across Australia, where small insects pass close enough for ambush hunting.
What spiders look similar to the Trapezoid crab spider / trapezium crab spider?
Common lookalikes can overlap in colour, size, web type or habitat. Use the similar spiders and common comparisons on this page to check alternatives before settling on a match.
Can I identify the Trapezoid crab spider / trapezium crab spider by photo?
A photo can help if it shows the whole spider, markings, size and where it was found. For the Trapezoid crab spider / trapezium crab spider, also compare the checklist clues and what to check next rather than relying on colour alone.