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 Conservation listings displayed on Florabase may also be out of date.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

Herposiphonia mermaidensis Huisman

Reference
Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae 514-515, Fig. 149A-E (2018)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Current

Scientific Description

Habit and structure. Thallus with prostrate axes bearing lateral indeterminate and dorsal determinate branches alternately, the successive indeterminate branches on alternate sides. Prostrate axes 70–90 µm diam., with 9 pericentral cells [mature segment L:B 2–2.6], attached to the substratum by elongate unicellular rhizoids arising from the ventral surface, distal on each segment. Determinate branches arising from the same dorsal position (i.e. not deflected from side to side), more than 7 mm and 40 segments long; basal segment short, with 4 pericentral cells, suprabasal segment with 7 or 8 pericentral cells, then more distal segments with 11–16 pericentral cells. Developing determinate branches strongly curved, 55–75 µm diam. [segment L:B to 1], initially lacking trichoblasts but these arising later on up to 10 apical segments in a spiral pattern. Mature branches 70–85 µm diam. [segment L:B 2–2.5]. Trichoblasts initially secund, becoming subdichotomous, to 1.2 mm long at maturity.

Distribution. Known only from Mermaid Reef, Rowley Shoals, Western Australia.

Habitat. epiphytic on Pterocladiella caerulescens in the subtidal.

[After J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 514–515 (2018)]