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The Western Australian Herbarium’s collections management system and census were set to read-only mode on 1 October 2025. Taxonomic updates published since this time are not being reflected in Florabase, herbarium collections, or Western Australia’s taxonomic names census (Nomos). Conservation listings displayed on Florabase may also be out of date. Please refer to DBCA’s Threatened species and communities webpage for the most recent Threatened and Priority Flora List, noting that recent taxonomic updates are similarly not included. Our database migration is moving to a staging phase. We thank you for your patience as we ensure the integrity of our biodiversity data, develop new workflows, and train staff to use the new systems. Please reach out to us if you have any questions or concerns.

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Actinotrichia fragilis (Forssk.) Børgesen

Reference
Dansk Bot.Ark. 8:6, Pl. 1, Fig. 4 (1932)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current
Image

Scientific Description

Habit and structure. Thallus to 7 cm high, grey-pink to orange-red, forming a hemispherical or spreading clump, subdichotomously branched at intervals of 2–10 mm. Axes 250–600 µm in diameter; emergent filaments either absent, randomly arranged, or in whorls at intervals of 150–200 µm. Medullary filaments 5–12 µm in diameter. Cortex 3 or 4 cells thick; inner cells 22–32 µm in diameter, with occasional lateral fusions; epidermal cells turbinate, 20–27 µm in diameter; emergent filaments cylindrical, to 550 µm long, with cells 10–13 µm in diameter.

Reproduction. Spermatangial cavities 150–250 µm in diameter; spermatangia spherical to obovoid, c. 5 × 7 µm. Cystocarps not observed. Tetrasporangia subspherical, 25–27 × 22–25 µm.

Distribution. Known from Coral Bay, W.Aust., presumably across northern Australia to the Great Barrier Reef, Qld. Widespread in tropical seas.

Habitat. A. fragilis growson rock or coral platforms in the subtidal.

John Huisman & Cheryl Parker, 3 August 2021

Distribution

IBRA Regions
Carnarvon, Dampierland, Northern Kimberley.
IBRA Subregions
Cape Range, Mitchell, Pindanland.
IMCRA Regions
Kimberley, Ningaloo, Pilbara (offshore).
Local Government Areas (LGAs)
Ashburton, Broome, Carnarvon, Derby-West Kimberley, Exmouth, Karratha, Wyndham-East Kimberley.