Flattened Bark Spider Identification in Australia

About the Flattened bark spider

Flattened bark spiders are distinctive ground-style hunters. Their unusually flattened body is the main clue, especially when one is found under bark, logs, rocks or outdoor shelter. A photo that shows the wafer-thin side profile and hiding place is more useful than brown or grey colour alone; do not peel back bark or probe a crevice to force an identification.

Exact-species hero photograph: Hemicloea rogenhoferi by Jon Sullivan, CC BY-SA 2.0, via Wikimedia Commons. This New Zealand photograph documents the exact species but is not an Australian locality record.

Exact-species specimen views

These licensed exact-taxon photographs show useful anatomy and variation. Use each caption for record and image context; no single image set represents every colour, posture or habitat.

How to identify a flattened bark spider cautiously

The first useful identification is the body plan, not the colour. Hemicloea rogenhoferi is a very flat ground spider in the family Trochanteriidae, with a wafer-thin body and legs that can tuck into narrow spaces beneath loose bark, rocks, logs or other shelter. In a sharp top or side view, the carapace and abdomen sit close to the substrate and the spider looks more like a flattened leaf or bark fragment than a normal huntsman. It is a wandering hunter rather than an orb-web or lace-web sitter. The World Spider Catalog accepts H. rogenhoferi and records Queensland and New South Wales, with an introduced population in New Zealand; several other Hemicloea species occur in Australia. A field photograph can support “flattened bark spider” or Hemicloea, but exact species should be reserved for a whole spider with a defensible locality and adult characters.

Clues that are not enough on their own

• Brown, grey or reddish colour alone, because substrate and lighting change the appearance
• A flat outline without a clear underside or substrate, because many spiders can crouch or flatten briefly
• A wall, shed or garden encounter without nearby bark, timber, rock or a whole-body view
• A rapid sideways run treated as proof of huntsman identity
• A New Zealand photograph or locality used as Australian range evidence
• The older Gnaphosidae label treated as current taxonomy without checking the World Spider Catalog
• One leg posture or cropped silhouette that hides spinnerets and body proportions
• A missing capture web treated as a species character rather than a broad hunting clue
• A phone-app match used to choose a species among several flat Australian spiders

Colour, sex and life-stage variation

Colour and apparent outline vary with substrate, sex, age and light. Individuals may be grey, tan, brown, reddish or mottled, and a spider pressed tightly beneath bark can look much darker than one on a pale rock. Females are generally larger and fuller-bodied; males and juveniles may be smaller, paler and harder to separate from other flat ground spiders. Legs can be folded under the body or spread during a rapid escape, changing the apparent width of the animal. The three exact-species photographs on this page are licensed H. rogenhoferi records from New Zealand: they document the species and its variation, but they are not Australian locality evidence. Do not use one dorsal pattern, a red-brown tint or a resemblance to a huntsman as a universal template. Record the measured body length, substrate, broad location and multiple angles.

Behaviour, web and retreat

Flattened bark spiders are active ambush hunters that use their thin profile to remain hidden in crevices and under surface layers. They can rush from bark or rock to seize small arthropods, then retreat into the same narrow shelter. No obvious capture web is expected, although short silk lines or a retreat may be present and should not be disturbed. A spider found wandering across a wall or path may simply be moving between shelters; the open surface is less informative than the body shape and nearby bark, timber or rock. Do not peel bark, lift a rock, prise open a fence gap or probe a crevice to force the spider into view. A fast sideways run is an escape response, not a diagnostic test and not evidence that the animal is a huntsman.

Australian distribution

Current World Spider Catalog taxonomy places Hemicloea rogenhoferi L. Koch, 1875 in Trochanteriidae and lists Australia (Queensland, New South Wales), with an introduced population in New Zealand. Older Australian resources may still group Hemicloea with Gnaphosidae, so a source may show conflicting family labels; the current WSC placement is retained here while the historical label is acknowledged. The state filters are deliberately limited to Queensland and New South Wales. Victoria, the ACT and Tasmania are not inferred from a generic “eastern Australia” description, and a New Zealand photograph does not extend the Australian range. Other flat spiders, including additional Hemicloea and unrelated trochanteriid or ground-spider taxa, overlap in shape. Keep locality, date, substrate and whole-body views for expert review.

What to do if you find one

Leave a flattened bark spider under its bark, rock or timber shelter whenever possible. If it is on a wall or path, photograph from above and from a low side angle, include the nearby substrate, and place a ruler or familiar object beside it rather than touching it. Do not lift bark, turn rocks or put fingers into crevices; wear gloves before gardening and move timber with tools, not bare hands. If an indoor spider must be moved and no bite has occurred, use a wide container and card only when hands can remain clear, then release it into a nearby sheltered edge. For a suspected bite, wash the area and follow current Australian health advice; seek medical care for severe or persistent pain, spreading symptoms, infection signs or uncertainty. A photo match cannot determine medical risk.

Compare with similar spiders

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

• Flat rock spider — Flat rock spider - trochanteriid flat rock spiders share the flattened ground-hunter outline; use the substrate, locality and whole body rather than assuming every flat spider is H. rogenhoferi.
• Australian flattie spider — Australian flattie spider - Karaops and related selenopids are also very flat and fast, but their laterigrade leg arrangement and rock or wall habits require a different family-level comparison.
• Victorian huntsman spider — Victorian huntsman spider - Isopedella and other huntsmans can crouch under bark, yet the broader huntsman body, leg spread and eastern locality are not enough to prove a flattened bark spider.
• Huntsman spider — Huntsman spider - a large flat spider on a wall is a common misread. Keep the result at a broad flat-spider group when the carapace, spinnerets and substrate cannot be seen clearly.

Sources for this profile

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

• World Spider Catalog: Hemicloea rogenhoferi
• Australian Faunal Directory: Hemicloea rogenhoferi
• Atlas of Living Australia: Hemicloea rogenhoferi
• World Spider Catalog: Trochanteriidae family
• Australian Museum: Ground spiders
• Australian Museum: Classifying spiders
• Australian checklist: Hemicloea and Trochanteriidae
• Bush Blitz: Hemicloea rogenhoferi record context
• Wikimedia Commons: exact Hemicloea rogenhoferi photograph
• Wikimedia Commons: second exact Hemicloea rogenhoferi photograph
• Wikimedia Commons: third exact Hemicloea rogenhoferi photograph
• healthdirect: Spider bites

Profile review

Published by Spider Identifier Australia. Last factual review: 13 August 2026.