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Electronic Flora of South Australia Species Fact Sheet

Polysiphonia crassiuscula Harvey 1859b: 299; 1863, synop.: xx.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Polysiphonieae

Selected citations: J. Agardh 1863: 986. De Toni 1903: 885. Guiler 1952: 103. Lucas 1909: 41; 1929a: 21; 1929b: 51. Lucas & Perrin 1947: 266. Reinbold 1897: 56. Segi 1966: 506, pl. 8A. Shepherd 1983: 83. Sonder 1880: 34. Womersley 1979: 488, fig. 8A–C.

Thallus (Fig. 84A) dark red-brown, usually 10–36 cm high, with a single basal axis and numerous laterals which may develop almost as strongly as the main axis, profusely branched on all sides with dense, often fastigiate, tufts of lesser branches with constricted bases, readily denuded leaving only the main branches. Holdfast of a cellular disc, 1–3 mm across, without formation of distinct rhizoids; usually epilithic. Structure. Lower main axes 0.5–1 (–4) mm in diameter, heavily corticated and usually denuded, mid branches commonly 0.5–1 mm in diameter, decreasing to 150–250 µm in diameter in slightly corticated branches with segments L/D (0.8–) 1.7–2.3; ecorticate branchlets 50–180 µm in diameter with segments L/D 1–1.5 (–2), usually distinctly basally constricted (Fig. 84C) and hence L/D often 2–4 in basal segments, tapering evenly to a somewhat pointed, straight, apex with profuse trichoblasts unless denuded; lateral branches arising from basal cell of trichoblasts but most branching cicatrigenous. Pericentral cells 4, elongate throughout the thallus, ecorticate in branchlets but soon becoming corticate, sometimes twisted; cortication commencing with short cells cut off usually from the posterior corners of the pericentral cells, then elongating and dividing to form rows of cells lying over the longitudinal walls of the pericentral cells, later extending to give complete coverage, and in older branches and the axis forming a cortex several to many cells thick. Trichoblasts light brown-red in colour due to rhodoplasts in the cells, slender, basal cells 15–30 (–40) µm in diameter, 2–4 times furcate, formed on every segment with a divergence of 1/4, often persistent for some distance behind the apices. Rhodoplasts discoid, densely aggregated.

Reproduction: Gametophytes dioecious. Carposporophytes with a small basal fusion cell and branched gonimoblast with ovoid to clavate terminal carposporangia 70–130 µm in diameter. Cystocarps (Fig. 84B) distinctly stalked, ovoid to globular and often broader than long when mature, non-urceolate, 280–450 (–700) µm in diameter; pericarp ostiolate, 2 cells thick, outer cells isodiametric, angular. Spermatangial branches developing as one branch of a trichoblast, cylindrical, 130–200 µm long and 50–75 µm in diameter, without a sterile apical cell when mature.

Tetrasporangia (Fig. 84C) in normally unbranched, acicular, cicatrigenous laterals, forming slightly spiral or almost straight rows decreasing regularly in size from the oldest sporangium, with mature sporangia almost as wide as and slightly bulging the branch, subspherical, ovoid, 80–230 µm in diameter when mature.

Type from East Coast, Tas. (Gunn); holotype in TCD; isotype in BM.

Selected specimens: N Spencer Gulf, S. Aust., 12–15 m deep (Shepherd, 5 and 6.ix.1973; AD, A44211 and A44459). Investigator Strait, S. Aust., 22–32 m deep (Watson, 9.i.1971; AD, A38459 and 25.i.1971; AD, A38185). Off Troubridge I., S. Aust., 14 m deep (Shepherd, 4.ii.1969; AD, A33786). Holdfast Bay, S. Aust., 24 m deep (Shepherd, 30.xii.1966; AD, A31598). 20 km WSW of Outer Harbour, S. Aust., 22–25 m deep (McFarlane, 11.ix.1975; AD, A46632). Vivonne Bay, Kangaroo I., S. Aust., 1–4 m deep on jetty piles (Kraft, 6.iv.1972; AD, A42365). Stanley Beach, Kangaroo I., S. Aust., drift (Womersley, 27.i.1957; AD, A20851). Cape Jaffa, S. Aust., drift (Womersley, 22.xi.1998; AD, A67966). Robe, S. Aust., drift (Womersley, 15.xii.1970; AD, A37820). Rocky Cape, Tas., drift (Gordon, 18.i.1966; AD, A29964). Off Satellite I., D'Entrecasteaux Ch., Tas., 12 m deep (Shepherd, 17.10972; AD, A41639).

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

Distribution: N Spencer Gulf to Robe, S. Aust., and N and SE Tasmania.

Taxonomic notes: P. crassiuscula is a distinctive species, characterised by its habit, the heavy cortication on lower branches, ecorticate and basally constricted branchlets, preponderance of cicatrigenous branches, and branching from the basal cell of trichoblasts. The type specimens of Gunn are very much denuded and virtually bare of branchlets; however the size and branching, heavy cortication of the larger branches and the few ecorticate branchlets agree well with the above collections in AD. The major branching is rather variable; in some specimens it is extensive near the base while in others there is a single percurrent axis. In one specimen (AD, A33786) this percurrent axis has apparently lasted for some time and is abnormally thick (up to 6 mm on the herbarium sheet, probably about 4 mm in life). Although the trichoblasts are slightly pigmented, sometimes with numerous rhodoplasts, all structural features agree well with those of Polysiphonia.

P. crassiuscula is clearly a deep-water species, and the type specimens were almost certainly rather old drift specimens.


AGARDH, J.G. (1863). Species Genera et Ordines Algarum. Vol. 2, Part 3, pp. 787–1291. (Gleerup: Lund.)

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

GUILER, E.R. (1952). The marine algae of Tasmania. Checklist with localities. Pap. Proc. R. Soc. Tasmania 86, 71–106.

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. III. Flora Tasmaniae. Vol. II, pp. 282–343, Plates 185–196. (Reeve: London.)

HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)

LUCAS, A.H.S. & PERRIN, F. (1947). The Seaweeds of South Australia. Part 2. The Red Seaweeds. (Govt Printer: Adelaide.)

LUCAS, A.H.S. (1909). Revised list of the Fucoideae and Florideae of Australia. Proc. Linn. Soc. N.S.W. 34, 9–60.

LUCAS, A.H.S. (1929a). The marine algae of Tasmania. Pap. Proc. R. Soc. Tasm. 1928, 6–27.

LUCAS, A.H.S. (1929b). A census of the marine algae of South Australia. Trans. R. Soc. S. Aust. 53, 45–53.

REINBOLD, T. (1897). Die Algen der Lacepede und Guichen Bay und deren náherer Umgebung (Slid Australien), gesammelt von Dr. A. Engelhart-Kingston. Nuova Notarisia 8, 41–62.

SEGI, T. (1966). The type or authentic specimens of Polysiphonia in Europe. Rep. Fac. Fish., Prefect. Univ. Mie 5, 503–516, Plates 1–25.

SHEPHERD, S.A. (1983). Benthic communities of upper Spencer Gulf, South Australia. Trans. R. Soc. S. Aust. 107, 69–85.

SONDER, O.W. (1880). In Mueller, F., Fragmenta Phytographiae Australiae. Supplementum ad volumen undecinum: Algae Australianae hactenus cognitae, pp. 1–42, 105–107. (Melbourne.)

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

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. 84 A–C.

Figure 84 image

Figure 84   enlarge

Fig. 84. A–C. Polysiphonia crassiuscula (A, AD, A37820; B, AD, A44459; C, AD, A46632). A. Habit. B. Branch with cystocarp. C. Branch with early cortication bearing tetrasporangial branchlets. D–H. Polysiphonia daveyae (D–F, AD, 32926; G, AD, A49183; H, AD, A26776). D. Habit. E. Early stage of cortication, with cicatrigenous branchlets. F. Branches with cystocarps. G. Spermatangial branches. H. Tetrasporangial branches. (All as in Womersley 1979, courtesy of Aust. J. Bot.)

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