- Reference
- Austral.J.Mar.Freshwater Res. 29:212-214, Figs 1A-B, 5A-C (1978)
- Conservation Code
- Not threatened
- Naturalised Status
- Native to Western Australia
- Name Status
- Current
Scientific Description
Habit and structure. Thallus grey-red to red, 2–12 mm high, erect filaments sparsely subdichotomous or lateral, basal filaments prostrate, attached by rhizoids from periaxial cells or their derivatives, 1–3 cells long and with multicellular pads; epiphytic on Amphibolis, Posidonia or on algae associated with these seagrasses. Structure. Branches 70–150 µm in diameter, tapering only slightly above, with relatively straight apices; axial cells usually L/D 0.7–2, with narrow nodal bands 2 cells long and internodal spaces 3–6 times as long as nodal bands. Periaxial cells usually 6, each cutting off laterally one (occasionally 2, rarely none) pseudoperiaxial cell which lies in the periaxial ring, and each cell of this ring then cutting off acropetally a single cortical cell, thus forming a nodal band 2 cells long. Each direct derivative of the true periaxial cells producing a short tapering filament (55–100 µm long) of 3–6(–7) cells (with a rounded apex) which projects outwardly and forward from the axis; the true periaxial cells usually do not produce such a filament, though both they and the acropetal derivatives of the pseudoperiaxial cells may do so; slender terminal hairs often present on these filaments. Rhodoplasts discoid in cortical cells, linear in axial cells.
Reproduction. Gametophytes dioecious. Carposporophytes globular, 120–180(–200) µm across, with angular to ovoid carposporangia 30–40 µm across, subtended by 1–3 short branchlets. Spermatangial masses cut off first from adaxial nodal cells, later developing all around the nodes. Tetrasporangia cut off from enlarged periaxial cells, usually single per node and abaxial, often with further sporangia formed later from adjacent cells, protected by slightly greater development of nodal filaments (some basally dichotomous) than in sterile plants; tetrasporangia 50–70 µm in diameter, tetrahedrally to decussately divided.
Distribution. Shark Bay, W. Aust., to Port Stephens, N.S.W. and Lord Howe I.
Habitat. Typically associated with seagrass beds, between 2.5 and 12m deep, in areas of moderate water movement.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 384–385 (1998)]