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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 Conservation listings displayed on Florabase may also be out of date.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.

The notice period started at 12:00 pm on Wednesday, 1 October 2025 +08:00 and will end at 12:00 pm on Friday, 1 January 2027 +08:00.

Sebdenia polydactyla (Børgesen) M.P.Balakr.

Reference
Proc.Symp.Algol.New Delhi 1959:89 (1961)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current

Scientific Description

Habit and structure. Thallus erect, pale pink, flabellate, to 8–14 cm tall, arising from a discoid holdfast, dichotomously branched with rounded axils. Axes terete to slightly flattened, mostly soft but turgid, 2–4 mm diam. near the base and in some specimens cartilaginous, broadening to 8–12 mm wide, broadest just below dichotomies. Structure multiaxial, with a filamentous medulla of elongate cylindrical cells 15–20 µm diam. [L:B c. 10], grading to an outer medulla of stellate cells, 3 or 4 layers of large hyaline cells, then a small-celled cortex, the surface cells subspherical and 5–10 µm diam. Spherical to obovoid vesicular cells 25–35 µm diam., borne laterally on medullary filaments.

Reproduction. Reproductive structures not seen.

Distribution. Widely distributed in tropical and warm-temperate regions of the Indian Ocean.

Habitat. Epilithic, often on rocks in sandy regions of the subtidal.

[After J.M. Huisman & G.W. Saunders in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 302–303 (2018)]

John Huisman & Olga Nazarova, 3 August 2021

Distribution

IBRA Regions
Dampierland, Geraldton Sandplains, Pilbara.
IBRA Subregions
Geraldton Hills, Pindanland, Roebourne.
IMCRA Regions
Abrolhos Islands, Canning, Central West Coast, Kimberley, Leeuwin-Naturaliste, Pilbara (nearshore), Pilbara (offshore).
Local Government Areas (LGAs)
Ashburton, Broome, Cockburn, Derby-West Kimberley, Greater Geraldton, Karratha, Port Hedland, Wyndham-East Kimberley.