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Polysiphonia australiensis Womersley 1979: 491, fig. 9A–D.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Polysiphonieae

Selected citations: Huisman & Walker 1990: 439. Shepherd & Womersley 1981: 367. Silva et al. 1996: 537.


Polysiphonia dasyoides Zanardini sensu Womersley 1947: 245; 1948: 150, 157, 160; 1950: 184; 1953: 38. [NON P. dasyoides Zanardini 1874: 489. De Toni 1903: 954, from Georgetown, Tas. (probably Echinothamnion hookeri).]

Thallus (Fig. 85A) dark red-brown, 4–10 (–15) cm high, with one to several erect, percurrent axes from a clumped base, axes much branched above with fastigiate lateral branch systems usually not more than 1 cm long, often denuded below. Holdfast of tightly clumped rhizoids cut off from basal pericentral or cortical cells; epilithic or epiphytic on other algae. Structure. Lower axes 0.7–1.5 mm in diameter, heavily corticated, decreasing gradually to upper lightly corticated axes or branches 300–500 µm in diameter with segments L/D 0.3–0.8, within about 1 cm of branch apices; ecorticate branchlets 120–180 µm in diameter with segments L/D 0.7–1 (–1.3), decreasing to 70–100 µm in diameter with segments L/D 0.3–0.7 near the apices; trichoblasts usually profuse, branches replacing trichoblasts and commonly cicatrigenous from older branches. Pericentral cells 4, usually elongate with L/D (1–) 1.2–2 (–2.5) in ecorticate parts except near apices, becoming corticate from the sides or corners of pericentral cells with corticating filaments developing longitudinally between the pericentral cells, soon spreading as a complete surface layer, becoming several cells thick on older axes; trichoblasts or scar cells present on every segment with a divergence of 1/4, relatively robust (basal cells 35–45 µm in diameter), 2–3 (–4) times furcate. Rhodoplasts discoid, scattered.

Reproduction: Gametophytes dioecious. Carposporophytes with a small basal fusion cell and short gonimoblast bearing clavate terminal carposporangia 20–40 µm in diameter. Cystocarps (Fig. 85B) stalked, ovoid, usually becoming urceolate with a pronounced neck, 200–350 µm in diameter and 300–400 µm long (excluding stalk); pericarp ostiolate, 2 cells thick, outer cells isodiametric to elongate, angular, with the ostiolar cells considerably enlarged. Spermatangial branches (Fig. 85C) developing as one branch of a trichoblast, cylindrical to tapering, 150–300 µm long and 40–80 µm in diameter, with 1–2 sterile apical cells when mature.

Tetrasporangia (Fig. 85D) forming gently spiralling series in upper branchlets, usually extending below 1–3 branches, moderately distorting the segments and occupying 0.5–0.7 of the segment diameter when mature, subspherical, 40–60 µm in diameter.

Type from Vivonne Bay, Kangaroo I., S. Aust., mid eulittoral, south side Ellen Point (Womersley, 22.xi.1968); holotype in AD, A32913-"Marine Algae of southern Australia" No. 210.

Selected specimens: Rottnest I., W. Aust., on Sargassum (Gordon, 12.xi.1968; AD, A33131). Frenchmans Bay, Albany, W. Aust., upper sublittoral (Woelkerling, 2.ii.1978; AD, A49278). Twilight Corner, Esperance, W. Aust., on Balanus, lower eulittoral (Woelkerling, 29.i.1978; AD, A42989). Point Sinclair, S. Aust., lower eulittoral (Womersley, 26.i.1951; AD, A15225). Greenly Beach, Eyre Pen., S. Aust., lower eulittoral (Parsons, 15.v.1968; AD, A32558). Wanna, S. Aust., mid eulittoral pool (Womersley, 21.viii.1967; AD, A31865). Pennington Bay, Kangaroo I., S. Aust., in pool (Womersley, 21.xi.1968; AD, A32904). Back Beach, Little Dip Conservation Park, SE S. Aust., lower eulittoral on outer reef (Womersley, 24.iv.2000-"Marine Algae of southern Australia" No. 210a). Apollo Bay, Vic., (McLennan, Aug. 1951; AD, A16408). Blairgowrie, Vic., on Laurencia, at low tide level on ocean beach (Sinkora A2452, 23.xi.1978; AD, A60900). Curtis I., Bass Strait, Vic., lower eulittoral (King, ?; MEL, 20888; AD, A39446). Three Hummocks I., NW Tas., on Laurencia, low eulittoral (Bennett, 17.i.1954; AD, A19701).

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

Distribution: Rottnest I., W. Aust., to Curtis I., Bass Strait, Vic., and Three Hummock I, NW Tasmania.

Taxonomic notes: P. australiensis is a distinctive species, largely confined to the lower and mid eulittoral zones on sloping rock on rough-water coasts; occasionally it is epiphytic in the same habitats. Of the southern Australian corticate species it is most closely related to P. daveyae, but differs in habit, in the branches replacing trichoblasts, in having elongate rather than isodiametric pericentral cells in ecorticate parts, in its habitat and in reproductive details such as the enlarged ostiolar cells of the pericarp, in having one or two sterile apical cells to the spermatangial branches, and in that the tetrasporangia usually extend below 2 or 3 branchings.


DE TONI, G.B. (1903). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 3. pp. 775–1521 + 1523–1525. (Padua.)

HUISMAN, J.M. & WALKER, D.I. (1990). A catalogue of the marine plants of Rottnest Island, Western Australia, with notes on their distribution and biogeography. Kingia 1, 349–459.

SHEPHERD, S.A. & WOMERSLEY, H.B.S. (1981). The algal and seagrass ecology of Waterloo Bay, South Australia. Aquat. Bot. 11, 305–371.

SILVA, P.C., BASSON, P.W. & MOE, R.L. (1996). Catalogue of the Benthic Marine Algae of the Indian Ocean. (Univ. California Press: Berkeley.)

WOMERSLEY, H.B.S. (1947). The marine algae of Kangaroo Island. I. A general account of the algal ecology. Trans. R. Soc. S. Aust. 71, 228–252.

WOMERSLEY, H.B.S. (1948). The marine algae of Kangaroo Island. II. The Pennington Bay Region. Trans. R. Soc. S. Aust. 72, 143–166, Plates 10–15.

WOMERSLEY, H.B.S. (1950). The marine algae of Kangaroo Island. III. List of Species 1. Trans. R. Soc. S. Aust. 73, 137–197.

WOMERSLEY, H.B.S. (1953). The Archipelago of the Recherche. 3b. Marine Algae. Aust. Geogr. Soc. Rep. No. 1, Part 3B, pp. 36–38.

WOMERSLEY, H.B.S. (1979). Southern Australian species of Polysiphonia Greville (Rhodophyta). Aust. J. Bot. 27, 459–528.

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

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

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustration in Womersley Part IIIA, 2003: FIG. 85 A–D.

Figure 85 image

Figure 85   enlarge

Fig. 85. A–D. Polysiphonia australiensis (A, C, D, AD, A32913; B, AD, A49278). A. Habit. B. Branches with cystocarps. C. Spermatangial branches. D. Tetrasporangial branches. E–H. Polysiphonia abscissoides (E, F, H, AD, A49188; G, AD, A47589). E. Habit. F. Branches with cystocarps. G. Spermatangial branches. H. Tetrasporangial branches. (All as in Womersley 1979, courtesy of Aust. J. Bot.)

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