- Reference
- Mar.Benth.Fl.S.Australia 273 (1987)
- Conservation Code
- Not threatened
- Naturalised Status
- Native to Western Australia
- Name Status
- Current
Scientific Description
Habit and structure. Thallus medium brown, usually 15–50(–65) cm long, with one to a few percurrent axes (often basally denuded), densely branched radially with long laterals bearing shorter branches to 4 or 5 orders, with most branches covered with discrete tufts of assimilatory filaments giving a soft, tomentose, appearance; holdfast rhizoidal, 2–6 mm across and 1–4 mm long; epilithic. Growth apical, with a relatively small, convex branch meristem surmounted by a tuft of trichothallic assimilatory filaments 1–3(–5) mm long, each with a vague meristem 2–4 cells above their base, (6–)8–10(–12) µm in diameter with cells L/B6–12 above. Fronds terete, 1–2 mm in diameter below, tapering gradually to (50–)100–250 µm in diameter near the apices, with tufts of assimilatory filaments and short laterals scattered over the branches with smooth cortex between them. Structure haplostichous and pseudoparenchymatous, with a central medulla of elongate cells, outer medulla of shorter, broader cells decreasing in size to the 1–cell thick cortex of small, angular, phaeoplastic cells, more or less in rows, 10–16(–22) µm across and L/B(0.7–)1–1.5(–2). Tufts of assimilatory filaments developing from cortical cells, similar to the apical filaments.
Reproduction. By sessile, clavate, unilocular sporangia, accompanied by paraphyses, forming a sorus around the surface tufts of assimilatory filaments, with the sori increasing in diameter but remaining discrete; the base of each sorus slightly concave, the paraphyses forming a slightly convex cluster. Paraphyses elongate-clavate, 60–80 µm and 5–8 cells long with the terminal cell subspherical to pyriform, 10–14 µm in diameter. Sporangia clavate, 30–50 µm long and 10–16 µm in diameter. Gametophyte unknown.
Distribution.From Flinders Bay, W. Aust., to the Snowy River Mouth, Vic., and around Tas.
Habitat. A. australis is a deep water (2–41 m) and fairly common species on rough-water to sheltered coasts.
[After Womersley, Mar. Benthic Fl. Southern Australia II: 273 (1987)]