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Service Notice

The Western Australian Herbarium’s collections management system, WAHerb, and DBCA’s flora taxonomic names application, WACensus, have been set to read-only mode since 1 October 2025. Recent taxonomic changes are not currently being reflected in Florabase, herbarium collections, or the census. Due to the rapidly approaching holiday season and associated agency and facility soft closures, along with the substantial work involved in data mapping, cleaning, and verification, the migration to the new collection management software is not expected to occur before 1 March 2026, when a further update will be provided. Please reach out to us if you have any questions or concerns.

The notice period started at 9:45 am on Friday, 12 December 2025 +08:00 and will end at 12:00 pm on Monday, 2 March 2026 +08:00.

Ulva rigida C.Agardh

Reference
Spec.Alg. 410-411 (1822)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current

Scientific Description

Habit and structure. Thallus dark green below, lighter above, epilithic or on seagrasses (e.g. Amphibolis), 4–20(–30) cm high, with several broad fronds from the holdfast, usually much and irregularly divided and lacerate or lobed, 1–6 cm across, margin entire, surface smooth. Cells in surface view arranged in short rows above, soon becoming irregularly arranged, isodiametric to elongate, 10–20(–25) µm broad and 20–25(–30) µm long, basal rhizoid-producing cells larger; pyrenoids 1(–2) per cell. Thallus 45–60(–70) µm thick in upper parts with cells in sectional view L/B about 1(–1.5) and 18–25 µm long, 80–110 µm thick in mid and lower parts with cells L/B 1.5–2(–2.5) and 22–40 µm long, and (120–)200–250(–300) µm thick near the base with a broad central mass of dense rhizoids, with cells L/B 1–1.5(–2) and 25–40 µm high.

Reproduction. Not recorded.

Distribution. Common in southern Australia, from Whitfords Beach (Perth), W. Aust., to Avoca Beach, N.S.W. and around Tasmania.

Habitat. On coasts of strong to moderate wave action, just above and below low tide level.

[After Womersley, Mar. Benthic Fl. Southern Australia I: 141-142 (1984) as Ulva australis]

John Huisman & Cheryl Parker, 3 August 2021

Distribution

IBRA Regions
Carnarvon, Swan Coastal Plain, Yalgoo.
IBRA Subregions
Cape Range, Edel, Perth.
IMCRA Regions
Central West Coast, Leeuwin-Naturaliste.
Local Government Areas (LGAs)
Ashburton, Cambridge, Cockburn, Shark Bay.