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Electronic Flora of South Australia Species Fact Sheet

Dipterosiphonia prorepens Falkenberg 1901: 328.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Herposiphonieae

Selected citations: De Toni 1903: 1050. May 1965: 380?


Polysiphonia prorepens sensu Harvey 1855a: 541; 1862a; pl. 185B; 1863, synop.: xxi. J. Agardh 1863: 917. Kützing 1864: 12, pl. 36a-f. Sonder 1880: 35.

Herposiphonia prorepens sensu Lucas 1909: 45. Lucas & Perrin 1947: 293, fig. 136.

Thallus (Fig. 134A) dark red-brown, densely clothing the host for up to several cm, 2–6 mm high (thick) with prostrate axes producing alternate pairs of determinate laterals (Fig. 134B) which soon become more or less erect and closely adjacent on the axes, with the branches of the anterior laterals developing as well as the posterior laterals; the anterior laterals are flexed forward on the axes and the posterior one emitted more directly. Attachment by rhizoids; epiphytic, especially on the stems of Amphibolis. Structure. Axial apical cells hemispherical, 12–20 µm in diameter, segmenting transversely and the subapical cells obliquely in the pattern of the genus, with the anterior determinate lateral branched and the posterior simple (Fig. 134B), all soon flexed upwards and free from the substrate (Fig. 134E). Axes and laterals with (7–) 8 pericentral cells, axes 130–200 µm in diameter with segments L/D 0.3–0.5, determinate laterals terete, 50–120 µm in diameter with segments L/D 0.2–0.5 (–0.8), tapering slightly throughout. Trichoblasts arising from subapical cells of determinate laterals, 300–1000 µm long, much branched, basal cells 16–30 µm in diameter, L/D 1–2, longer and slenderer above. Rhizoids cut off from axial pericentral cells, unicellular with multicellular haptera. Cells uninucleate; rhodoplasts discoid to elongate, chained in larger cells.

Reproduction: Gametophytes dioecious. Procarps on subrabasal cell of trichoblasts, soon polysiphonous. Carposporophytes with a small basal fusion cell and a much branched gonimoblast with clavate terminal carposporangia 20–30 µm in diameter. Cystocarps (Fig. 134C) lateral on determinate laterals, short-stalked, ovoid, 450–650 µm in diameter; pericarp ostiolate, 2 cells thick, ecorticate, outer cells angular, isodiametric. Spermatangial organs (Fig. 134D) replacing trichoblasts, tapering, 80–180 µm long and 35–55 µm in diameter, with a sterile basal cell and usually 2–3 sterile apical cells.

Tetrasporangia (Fig. 134E, F) in determinate laterals, usually in straight series, not or slightly swelling the segments, 40–80 µm in diameter, with 2–3 cover cells.

Type from King George Sound, W. Aust., on Dicranema revolutum; lectotype Alg. Aust. Exsicc. No. 181, in Herb. Harvey, TCD.

Selected specimens: (all on stems of Amphibolis): Red Bluff, Kalbarri, W. Aust., upper sublittoral pools (Womersley, 15.ix.1979; AD, A51293-"Marine Algae of southern Australia" No. 404). Eucla, W. Aust., drift (Womersley, 5.x.1979; AD, A50696). Head of Great Australian Bight, S. Aust., upper sublittoral (Womersley, 4.ii.1954; AD, A19161). Tiparra reef, Spencer Gulf, S. Aust., 5 m deep (Shepherd, 24.ix.1971; AD, A39720). Goolwa, S. Aust., drift (Ricci, 19.v.1997; AD, A67080). D'Estrees Bay, Kangaroo I., S. Aust., outer reef pool (Womersley, 11.i.1950; AD, A12691). 3 km SW of Kingston, S. Aust., 6–7 m deep (R. Lewis, 28.xi.1972; AD, A42867).

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

Distribution: Kalbarri, W. Aust., to Kingston, S. Australia.

Taxonomic notes: The indeterminate apices show typical Dipterosiphonia structure, but this is obscured by the dense arrangement of the erect determinate laterals. D. prorepens is largely restricted to the stems of the seagrass Amphibolis, occasionally on other algae.

D. prorepens is ascribed to Falkenberg as a newly described species, distinct from Polysiphonia prorepens [= Herposiphonia prorepens (Harvey) Schmitz] from South Africa. Falkenberg (1901, p. 329) considered the illustration of Harvey (1862, pl. 185B) included both Australian and South African plants, but Wynne (1984c, p. 172) doubted this and it seems that pl. 185B is based entirely on the Australian species.


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.)

FALKENBERG, P. (1901). Die Rhodomelaceen des Golfes von Neapel und der angrenzenden Meeres-abschnitte. Fauna und Flora des Golfes von Neapel. Monogr. 26. (Friedländer: Berlin.)

HARVEY, W.H. (1855a). Some account of the marine botany of the colony of Western Australia. Trans. R. Jr. Acad. 22, 525–566.

HARVEY, W.H. (1862a). Phycologia Australica. Vol. 4, Plates 181–240. (Reeve: London.)

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

KÜTZING, F.T. (1864). Tabulae Phycologicae. Vol. 14. (Nordhausen.)

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.

MAY, V. (1965). A census and key to the species of Rhodophyceae (red algae) recorded from Australia. Contr. N.S. W. Natl Herb. 3, 349–429.

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

WYNNE, M.J. (1984c). Notes on Herposiphonia (Rhodomelaceae, Rhodophyta) in South Africa, with a description of a new species. Cryptogamie: Algol. 4, 167–177.

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. 134.

Figure 134 image

Figure 134   enlarge

Fig. 134. Dipterosiphonia prorepens (A, C, D, F, AD, A19161; B, E, AD, A50696). A. Habit, on stems of Amphibolis. B. Branching pattern of apex. C. Cystocarps on determinate branches. D. Erect branches with spermatangial organs. E. Erect determinate laterals with tetrasporangia. F. Tetrasporangia in determinate laterals.

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