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Polysiphonia daveyae Reinbold 1899: 49.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Polysiphonieae

Selected citations: De Toni 1903: 913. Lucas 1909: 41; 1929b: 51. Lucas & Perrin 1947: 265. Shepherd & Womersley 1981: 367. Womersley 1948: 162; 1950: 185; 1956: 82; 1979: 490, fig. 8D–H.

Thallus (Fig. 84D) brown-red, 3–16 cm high with a single, erect basal axis, profusely irregularly branched on all sides with generally patent branching, more fastigiate above.

Attachment by numerous unicellular rhizoids cut off from pericentral and cortical cells, often aggregated to form a discoid holdfast; usually epiphytic (on Posidonia, Codium galeatum and other algae). Structure. Lower main axes 1–2 mm in diameter, moderately to heavily corticated, decreasing to 500–800 µm in diameter with segments L/D 0.3–0.5 (–0.8) in mid branches which are slightly to moderately corticated, then to 150–250 µm in diameter with segments L/D 0.3–0.8 (–1) in not or scarcely corticated branches, with ultimate branchlets 50–75 µm in diameter with mature segments L/D 0.5–1, and tapering evenly and markedly to a slender, erect apex; trichoblasts usually soon lost, branches arising from the basal cell of trichoblasts and often cicatrigenously from older branches. Pericentral cells 4, more or less isodiametric in surface view throughout the thallus but often 1.5–2 times as long as broad near the apices, becoming corticated from their corners (Fig. 84E) and cortication of short cells spreading around the pericentral cells as seen in surface view, becoming complete in older branches and several layers thick on old axes; trichoblasts (or scar cells) present on every segment with a divergence of i/4, relatively slender (basal cells 20–25 µm in diameter), 2–4 times furcate. Rhodoplasts discoid and usually in chains.

Reproduction: Gametophytes dioecious. Carposporophytes with a small basal fusion cell and short gonimoblast bearing clavate terminal carposporangia 25–45 µm in diameter. Cystocarps (Fig. 84F) short-stalked, subspherical to ovoid, non-urceolate, 300–500 µm in diameter; pericarp ostiolate, 2 cells thick, outer cells angular, isodiametric. Spermatangial branches (Fig. 84G) developing as one branch of a trichoblast, cylindrical, 160–250 µm long and 50–80 µm in diameter, without a sterile apical cell when mature.

Tetrasporangia (Fig. 84H) forming gently spiral series in single branchlets, occasionally with a small lateral above, not or slightly bulging the segments and occupying about half the branch width when mature, subspherical to ovoid, 50–90 µm in diameter.

Type from Investigator Strait, S. Aust. (Davey 166); holotype (?) in Herb. Reinbold, M; isotype in AD, A1180.

Selected specimens: Frenchmans Bay, Albany, W. Aust., drift (Parsons, 18.xi.1968; AD, A33229). Venus Bay, S. Aust., drift (Womersley, 12.ii.1954; AD, A19492). Tiparra reef, S. Aust., on Lenormandiopsis, 12 m deep (Shepherd, 13.v.1982; AD, A53324). American R. inlet, Kangaroo I., S. Aust., drift at jetty (Womersley, 25.viii.1963; AD, A26776). Muston, Kangaroo I., S. Aust., 2–3 m deep (Womersley, 21.xi.1968; AD, A32926). Strawbridge Point, Kangaroo I., S. Aust., drift (Womersley, 29.x.1995; AD, A64622). Seal Bay, Kangaroo I., S. Aust., on Codium galeatum, drift (Womersley, 29.x.1966; AD, A31036). Robe, S. Aust., drift on Codium galeatum (Womersley, 12.ii.1978; AD, A49183).

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

Distribution: Frenchmans Bay, Albany, W. Aust., to Robe, S. Australia.

Taxonomic notes: P. daveyae is a distinctive species marked by its form, isodiametric or short pericentral cells throughout and considerable cortication in the lower parts. It is most closely related to P. australiensis, but the latter differs in habitat and in having elongate pericentral cells. It usually occurs in moderately deep water off coasts with moderate to strong wave action.


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

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

REINBOLD, T. (1899). Meeresalgen von Investigator Street (Süd Australien), gesammelt von Miss Nellie Davey (Waltham, Honiton). Hedwigia 38, 39–51.

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

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. (1956). The marine algae of Kangaroo Island 1V. The algal ecology of American River inlet. Aust. J. Mar. Freshw. Res. 7, 64–87, Plates 1–7.

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 D–H.

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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