Tmarus species
Slender Crab Spider (Tmarus) Identification Australia
A cautious genus-level guide to slender, twig-like Australian Tmarus crab spiders: laterigrade front legs, vegetation ambush and no prey-catching web.
Usually low risk“Slender crab spider” is a useful field label for a narrow, stem- or twig-like crab spider, but it is not a formal species name. This page uses Tmarus at genus level. Australian Tmarus are true crab spiders (Thomisidae), yet a photo often cannot distinguish one named Tmarus species from another, or reliably separate a narrow crab spider from a different hunter with a similar outline.
Quick identification
- A small-to-medium, narrow crab-spider outline on vegetation; record body length separately from the much wider leg span
- The first one or two leg pairs held forward or sideways in a laterigrade crab-spider posture, often more conspicuous than the rear legs
- An oval-to-elongate abdomen that may resemble a stem, leaf edge or plant debris, but is not a diagnostic shape by itself
- A still waiting posture on foliage, a leaf tip, grass or a twig rather than a spider occupying an orb, sheet, funnel or messy prey-catching web
- A sharp full-body upper view, front view, locality and habitat image; adult genital characters are needed to name a Tmarus species securely
What to check next
Photograph the top, side and front of the spider, then include a scale beside the plant and a wide view of the stem, leaf or shrub. If the laterigrade posture is clear but the narrow outline or adult detail is not, stop at Thomisidae or crab spider rather than forcing Tmarus or a named species.
When to seek medical help
Tmarus is not among the Australian spiders healthdirect identifies as medically important. Do not handle a spider to test an identification. For a minor witnessed bite, wash with soap and water and use a wrapped cold pack for local pain. Seek medical advice for severe or persistent pain, worsening swelling, infection signs or illness; call 000 for breathing difficulty, collapse or anaphylaxis. If the spider could instead be a funnel-web or mouse spider, use emergency first aid and call 000 rather than relying on an uncertain photograph.
Where it is usually seen
Vegetation: stems, leaves, shrubs, grass heads, garden plants and woodland-edge foliage. The exact microhabitat varies by species, so a single leaf, flower or twig is supporting context rather than proof of Tmarus.