Mirror Spider Identification in Australia

About the Mirror spider

“Mirror spider” or “sequinned spider” is an appearance label used for Thwaitesia, not a guaranteed species identification. Australia has two formally accepted named species, T. argentiopunctata and T. nigronodosa, both documented from Queensland; contributed observations labelled only to genus extend farther south. A likely match is only a few millimetres long, has delicate comb-footed-spider legs and a high, often square or twin-peaked abdomen broken into reflective silver plates and cream, green, yellow, red or dark areas. Macro views of the abdomen, eyes, underside and adult reproductive structures are needed to move beyond genus.

How to recognise a possible Australian Thwaitesia

Start with scale and body form. The better documented Australian species, T. argentiopunctata, has females around 4 mm and males about 2.5 mm; this is body length, excluding legs. A female has a high, deep, almost square abdomen, while a male is smaller and slimmer. The upper abdomen carries sharply reflective patches arranged like irregular tiles, separated by non-reflective coloured bands. They are internal optical structures rather than metal stuck to the cuticle. Thwaitesia belongs to Theridiidae, so the legs are fine and the last pair bears the comb of serrated hairs characteristic of comb-footed spiders, although that feature usually needs magnification. Exact Australian species separation is specialist work. World Spider Catalog recognises T. argentiopunctata and T. nigronodosa from Queensland and traces both from older Argyrodes names; adult genitalia, abdominal contours, dark nodes and original diagnostic figures matter more than a single sparkling dorsal photograph.

Clues that are not enough on their own

• Any silver speck on a leaf; dew, beetles, scales and reflective silk can create the same first impression
• Shine colour in one flash photograph, because reflected surroundings alter silver, gold, green and black tones
• A fine web assumed to be diagnostic when Thwaitesia web architecture is poorly documented
• A Queensland locality used to choose between T. argentiopunctata and T. nigronodosa
• Claims that visible plates always shrink under threat used as a required behaviour test

Colour, sex and life-stage variation

Apparent colour changes dramatically with light angle, focus and flash. A silver plate can look white, gold, copper, green or almost black when it reflects a different part of the surroundings. The spaces between plates expose cream, yellow, green, red-brown or dark abdominal tissue, and the balance differs among individuals and species. Females are fuller and show the mirror field most conspicuously; males are smaller, with enlarged palps when mature. Juveniles lack adult reproductive characters and may have a simpler pattern. Feeding, egg development and posture can expand the soft abdomen and change the gaps between reflective areas. Claims that every mirror spider actively shrinks its plates when alarmed are based largely on photographic observation and should not be treated as a universal field test without controlled study.

Behaviour, web and retreat

Field accounts place Australian Thwaitesia on leaves in humid rainforest and rainforest margins, often along creeklines. Like other tiny theridiids, it uses silk, but the available Australian species sources do not establish one distinctive web architecture. A few fine lines beneath or between leaves may function as a foothold, retreat or small prey-interception web; finding the spider resting on a bare leaf does not rule it out. Do not describe every nearby strand as a capture web or assume a large tangled web belongs to the mirror spider. It probably takes very small arthropods that contact its silk or foliage, but detailed Australian diet and daily activity studies were not found. The reflective mosaic is plausibly camouflage or disruptive appearance, yet its exact predator-deterrence function remains an inference rather than a settled identification character.

Australian distribution

The Australian Faunal Directory lists Thwaitesia as a native genus with two accepted Australian species. World Spider Catalog confines both named species—T. argentiopunctata and T. nigronodosa—to Queensland. At review time the exact Atlas genus concept returned 1,968 contributed records: 884 Queensland, 780 New South Wales, 297 Victoria, two Tasmania, one ACT, one Northern Territory and three without state. Those observations explain why the profile remains useful in eastern Australia, but many are genus-level photographs and do not extend the formal range of either named species. The state filters are therefore limited to Queensland, NSW and Victoria; rare Tasmanian, ACT and NT values need record-level review, and no Western Australian genus result appeared in this query. Atlas totals show reporting effort, not abundance.

What to do if you find one

Leave the spider and its leaf in place if possible. It is easy to lose or injure an animal this small by prodding, shaking foliage or trying to catch it with fingers. Shade harsh sunlight, steady the phone against a support and photograph from several angles; a short video while changing the light angle can separate true reflective plates from water droplets. If the leaf must be moved during gardening, cut a generous section of vegetation around it and place it in nearby shaded foliage rather than peeling the spider from silk. Keep pesticides away from creekline and rainforest-edge vegetation. Submit a record with body scale, exact locality, date, habitat and multiple views to a museum or biodiversity portal; do not label it T. argentiopunctata solely because that name dominates image searches.

Compare with similar spiders

Use body shape, web or retreat, location and behaviour together before settling on a likely match.

• Red house spider — Red house spider - Nesticodes rufipes is larger, reddish-brown and usually associated with indoor or sheltered tangle webs. It lacks the tiled reflective abdomen, but a tiny dark silhouette in silk can confuse without macro detail.
• Triangular spider — Triangular spider - Arkys species have an angular or heart-shaped abdomen and enlarged spined front legs for leaf ambush, but they do not have the delicate theridiid build or mirror-tile field and do not rely on a capture web.
• Daddy-long-legs spider — Daddy-long-legs spider - pholcids have extraordinarily long legs, a much more elongated body and loose room-corner webs. Flash spots on a tiny pholcid abdomen are reflections, not sequinned plates.
• Garden jumping spider — Garden jumping spider - Opisthoncus has dominant forward-facing eyes, a compact stalking body and stop-start jumps rather than delicate theridiid legs and sparse silk. Metallic glare alone does not make a mirror spider.

Sources for this profile

These accessible authoritative sources support the identification and bite-safety context on this page.

• Australian Faunal Directory: Thwaitesia
• Atlas of Living Australia: Thwaitesia
• World Spider Catalog: Thwaitesia
• World Spider Catalog: Thwaitesia argentiopunctata
• World Spider Catalog: Thwaitesia nigronodosa
• Lucid Theridiidae key: Thwaitesia argentiopunctata
• healthdirect: Spider bites

Profile review

Published by Spider Identifier Australia. Last factual review: 12 August 2026.