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Service Notice

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 Conservation listings displayed on Florabase may also be out of date.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

Caulacanthus ustulatus (Turner) Kütz.

Reference
Phycol.General. 395 (1843)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current

Scientific Description

Habit and structure. Thallus forming a tangled mat of decumbent axes attached to the substratum by clusters of multicellular rhizoids arising from outer cortical cells, with irregularly produced upright axes to 1.5–2.5 mm tall bearing sparse short lateral branches. Axes terete to slightly flattened, 100–350 µm in diameter, tapering to 60 µm in diameter just below the distinctly pointed apices. Central axis conspicuous, with cells 35–100 µm long and 12–20 µm in diameter when mature, each bearing a pair of di-trichotomously branching lateral filaments that traverse a small cavity before forming a pseudoparenchymatous cortex of 2–3 layers. Outer cortical cells angular in surface view, 5–12 µm broad.

Reproduction. Reproductive structures not seen.

Distribution. Widespread species along tropical and warm-temperate coasts. It has been recorded from most regions, with the exception of the western Atlantic and Central and South America.

Habitat. C. ustulatus grows on intertidal rock or is epiphytic on a variety of algae and mangroves.