Electronic Flora of South Australia Species Fact Sheet

Halymenia plana Zanardini 1874: 503.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Halymeniaceae

Selected citations: De Toni 1905: 1550.

Thallus (Fig. 57A) medium red, foliose, 10–30 cm high, becoming irregularly divided into broad lobes (2–) 4–6 (–10) cm across, 250–400 (–600) µm thick, with rounded axils and apices, surface smooth and mottled with darker red, irregularly shaped, areas 1–5 mm across, often aggregated into patches 4–8 mm across, margin smooth to slightly irregular, stipe 2–10 mm long, narrow-cuneate, with one to several fronds. Holdfast discoid, 2–6 mm across; epilithic. Structure (Fig. 57C) of a cortex 3–6 cells broad with a single (–2) outer layer of isodiametric cells 3–4 (–7) µm across and L/D 1–2 in thallus section, inner cells closely packed and pseudoparenchymatous, 15–22 µm across, mostly not becoming stellate; medulla lax to moderately dense with mostly irregular filaments (many transverse in young parts), becoming dense in older parts with no or few rhizoids, and with prominent refractive ganglionic cells (Fig. 57B). Rhodoplasts discoid to elongate and lobed, becoming ribbon shaped and branched in inner cells.

Reproduction: Sexual thalli probably dioecious. Carpogonial branch ampullae (Fig. 58A) with 3–5 secondary (and occasional tertiary) filaments, converging above and extending almost to thallus surface, and a 2-celled carpogonial branch. Auxiliary cell ampullae (Fig. 58B) with several long secondary and tertiary filaments, converging above in the outer cortex, with a prominent, large, auxiliary cell. Carposporophyte lying within the medulla, 80–160 µm across with dense, ovoid, carposporangia 8–12 µm across. Involucre slight, derived from the ampullary filaments, the lower cells of which elongate and the upper cells cut off short lateral chains around the small ostiole. Spermatangia not observed.

Tetrasporangia (Fig. 58C) scattered, on mid cortical cells, 15–25 µm long and 10–12 µm in diameter, cruciately divided.

Type from Port Phillip, Vic. (F. Mueller); holotype in Herb. Zanardini, Museo Civico di Storia Naturale, Venice.

Selected specimens: 16 km E of Eucla, S. Aust., drift (Womersley, 3.ii.1954; AD, A19299). Pearson I., S. Aust., 20–23 m deep (Shepherd & Turner, 29.iii.1982; AD, A53034). 15 km S of Southend, S. Aust., 4–6 m deep (Edyvane, 28.ix.1982; AD, A60757). South West R., Kangaroo I., S. Aust., 6 m deep (Mitchell, 24.viii.1963; AD, A26811). Amphitheatre Rock, West I., S. Aust., 18 m deep (Branden, 3.x.1972; AD, A42902). Port Elliot, S. Aust., drift (Womersley, 12.iv.1958; AD, A21371). Margaret Brock Reef, Kingston, S. Aust., 3 m deep (AIMS-NCI, Q66C 2469-Y, 18.ii.1989; AD, A59713). Baudin Rocks, Guichen Bay, S. Aust., 2–3 m deep (Shepherd, 15.ii.1975; AD, A46101). Stinky Bay, Nora Creina, S. Aust., drift (Womersley, 19.viii.1957; AD, A21208). 15 km S of Southend, S. Aust., 4–6 m deep (Edyvane, 28.ix.1982; AD, A60757). Point Lonsdale, Vic., 2–3 m deep under overhang (O'Brien, Kraft & J. Lewis, 19.ii.1976; MELU, A23241). Cape Woolamai, Vic., 15–18 m deep (Goldsworthy & Berthold, 16.ii.1990; AD, A60196). Walkerville, Vic., drift (Sinkora A2313, 7.iii.1976; AD, A48485). Cape Rochon, Three Hummock I., Tas., 14 m deep (Huisman, 10.ii.1991; MELU, A38664). Granville Harbour, Tas. (Sanderson, 11.xii.1987; MELU, A38238). Isle des Phoques, Great Oyster Bay, Tas., 15 m deep (McCauley, 27.ii.1990; AD, A60461).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: 16 km E of Eucla, S. Aust., to Walkerville, Vic., and around Tasmania.

Taxonomic notes: Halymenia plana occurs from 2–23 m depth on open coasts, under heavily shaded ledges at shallow depths, and is present throughout the year.

H. plana has a denser and more irregular medulla than most other species, though in young parts many transverse filaments occur. The auxiliary cell ampullae are also more branched, with short lateral branches around the ostiole, but the lower ampulla cells elongate as they do in other species of Halymenia.


DE TONI, G.B. (1905). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 4, pp. 1523–1973. (Padua.)

ZANARDINI, J. (1874). Phyceae Australicae novae vel minus cognitae. Flora (Regensburg) 57, 486–490, 497–505.

The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.

Author: H.B.S. Womersley & J.A. Lewis

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustrations in Womersley Part IIIA, 1994: PLATE 3 fig. 3; FIGS 57 A–C, 58 A–C.

Plate 3 image

Plate 3   enlarge

PLATE 3 fig. 1. Hildenbrandia expansa at Point Bunbury, Apollo Bay, Vic. (AD, A60088). fig. 2. Sonderopelta coriacea at Erith I., Bass Strait (AD, A45218). Photo: S.A. Shepherd. fig. 3. Halymenia plana at West I., S. Aust. (AD, A42902). Photo: K. Branden. fig. 4. Codiophyllum flabelliforme at Breaksea I., Albany, W. Aust. (in Murdoch). Photo: J.M. Huisman.

Figure 57 image

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Fig. 57. A–C. Halymenia plana (A, AD, A60757; B, C, AD, A60196). A. Habit. B. Squash showing refractive ganglionic cells and cystocarps. C. Transverse section of thallus with a cystocarp. D–G. Halymenia muelleri (D, E, AD, A60589; F, AD, A59159; G, AD, A22984). D. Habit. E. Transverse section of young thallus. F. Refractive ganglionic cells in surface squash. G. Transverse section of thallus with a carposporophyte (with lobes) and involucral filaments (branched around the slight ostiole).

Figure 58 image

Figure 58   enlarge

Fig. 58. A–C. Halymenia plana (A, B, AD, A60196; C, AD, A59713). A. Carpogonial branch ampulla. B. Auxiliary cell ampulla. C. Transverse section of cortex with tetrasporangia. D–F. Halymenia muelleri (D, E, AD, A60589; F, AD, A27090). D. Carpogonial branch ampulla. E. Auxiliary cell ampulla, spread laterally. F. Transverse section of cortex with tetrasporangia.

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