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Heterosiphonia australis (J. Agardh) De Toni 1903: 1217.

Phylum Rhodophyta – Order Ceramiales – Family Dasyaceae

Selected citations: Lucas 1912: 158. May 1965: 381. Parsons 1975: 606, figs 13, 14, 49A. May et al. 1978: 97. May & Larkum 1981: 456. Millar 1990: 436, fig. 60E. Millar & Kraft 1993:44.


Dasya australis J. Agardh 1863: 1183; 1890a: 83. Harvey 1863, synop.: xxiv. Sonder 1881: 36.

Dasya calliptera Sonder ex Kützing 1864: 28, p1. 78c-e.

Thallus (Fig. 221A) dark red, tufted, with polysiphonous, ecorticate, erect axes 2–3 cm high and 150–250 µm in diameter, arising from prostrate axes. Attachment by rhizoids; epilithic or epiphytic. Structure. Apices of axes (Fig. 222A) sympodial and distichous, developing 7–8 pericentral cells beginning 6–8 segments below apical cells, cut off in alternating sequence. Pseudolaterals 2 segments apart, each with 1–3 subdichotomies (Fig. 222B), 300–1000 µm long, cells (15–) 20–65 µm in diameter and L/D 0.8–1.5 (–2), tapering near the apices; basal segments may form 4–6 pericentral cells. Rhizoids developed from cells of pseudolaterals. Lateral sympodial axes arise from the basal cell of pseudolaterals. Rhodoplasts discoid in small cells, becoming chained in larger cells.

Reproduction: Gametophytes dioecious. Procarps (Fig. 222C) formed on lower cells of the pseudolaterals which develop 5 pericentral cells in alternating sequence, the last formed facing the axis and developing a carpogonial branch and 2 sterile groups which divide to form the pericarp initials. Post-fertilization, the auxiliary cell, central cell of the fertile segment, lower gonimoblast cells and adjacent pericentral cells contribute to the fusion cell, with the upper much branched gonimoblast bearing ultimate rows of ovoid carposporangia 20–35 µm in diameter. Cystocarps (Fig. 221B) small, urceolate, 400–600 µm in diameter, usually developing a slightly flared neck 0.5–0.8 as long as the base, sessile or shortly pedicellate; pericarp 2–3 cells thick, with slight cortication on the outer pericentral cells. Spermatangial branches (Fig. 221C, D) occurring on pseudolaterals, with a monosiphonous (rarely polysiphonous) stalk and terminated by a row of 4–6 sterile cells, 150–400 µm long and 40–85 µm in diameter, occasionally involving branches of pseudolaterals (Fig. 221D); axial cells with 4 pericentral cells producing initials which bear an outer layer of spermatangia.

Tetrasporangial stichidia (Fig. 222D) occur on cells of the pseudolaterals, sessile, basally polysiphonous, cylindrical to lanceoid and apically tapering with simple or branched apical filaments, 400–800 µm long and 120–175 µm in diameter with 15–25 fertile segments; each segment with 5 pericentral cells (Fig. 222E) formed alternately, each cell cutting off 2 pre-sporangial cover cells which divide transversely to form 4 cells covering each sporangium, and a tetrasporangium usually from each pericentral stalk cell, 35–65 (–70) µm in diameter.

Type from Port Jackson, N.S.W. (Harvey, Alg. Aust. Exsicc. 211L, as Dasya subsecunda Suhr?); holotype in Herb. Agardh, LD, 43630.

Selected specimens: Hopetoun, W, Aust., on Wilsonaea dictyuroides, drift (Parsons, 20.xi.1968; AD, A33365). Point Sinclair, S. Aust., lower eulittoral, shaded (Gordon, 3.xi.1968; AD, A33368). Greenly Beach, Eyre Pen., S. Aust., sublittoral fringe (Parsons, 15.v.1968; AD, A32562). Investigator Strait, S. Aust., 34m deep (Watson, 20.i.1971; AD, A39216). Vivonne Bay, Kangaroo I., S. Aust., mid eulittoral crevices, S side Ellen Point (Womersley, 22.xi.1968; AD, A32909). Nora Creina, S. Aust., upper sublittoral pools (Womersley, 18.viii.1953; AD, A19016). Apollo Bay, Vic. (McLennan, Aug. 1951; AD, A16497). Gabo I., Vic. on Rhodymenia, 28m deep (Shepherd, 19.ii.1973; AD, A43538). Lewisville Point, Triabunna, Tas., on Halopteris, sublittoral (Cribb 41.6, 18.iii.1950; AD, A16340).

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

Distribution: Hopetoun, W. Aust., to Coffs Harbour, N.S.W. (Millar 1990, p. 436) and E Tasmania.


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

AGARDH, J.G. (1890a). Till algernes systematik. Acta Univ. lund. 26(3), 1–125, Plates 1–3.

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

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. (1912). Supplementary list of the marine algae of Australia. Proc. Linn. Soc. N.S.W. 37, 157–171.

MAY, V. & LARKUM, A.W.D. (1981). A subtidal transect in Jervis Bay, New South Wales. Aust. J. Ecol. 6, 439–457.

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

MAY, V., COLLINS, A.J. & COLLETT, L.C. (1978). A comarative study of epiphytic algal communities on two common genera of seagrasses in eastern Australia. Aust. J. Ecol. 3, 91–104.

MILLAR, A.J.K. & KRAFT, G.T. (1993). Catalogue of marine and freshwater Red Algae (Rhodophyta) of New South Wales, including Lord Howe Island, South-western Pacific. Aust. Syst. Bot. 6, 1–90.

MILLAR, A.J.K. (1990). Marine red algae of the Coffs Harbour region, northern New South Wales. Aust. Syst. Bot. 3, 293–593.

PARSONS, M.J. (1975). Morphology and taxonomy of the Dasyaceae and Lophothalieae (Rhodomelaceae) of the Rhodophyta. Aust. J. Bot. 23(4), 549–713.

SONDER, O.W. (1881). In Mueller, F., Fragmenta Phytographiae Australiae. Supplementum ad volumen undecinum: Algae Australianae hactenus cognitae, pp. 1–42, 105–107. (Melbourne.)

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

Author: M.J. Parsons and H.B.S. Womersley

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia

Illustrations in Womersley Part IIIA, 1998: FIGS 221, 222 A–F.

Figure 221 image

Figure 221   enlarge

Fig. 221. Heterosiphonia australis (A, AD, A 19016; B, C, AD, A32562; D, AD, A43538). A. Habit. B. Cystocarp. C. Spermatangial branches. D. Spermatangia covering branches of pseudolaterals.

Figure 222 image

Figure 222   enlarge

Fig. 222. A–F. Heterosiphonia australis (A, B, AD, A32562; C–E, AD, A19016). A. Sympodial axis with developing pericentral cells and procarps. B. Mature pseudolateral. C. Mature procarp. D. Mature stichidia. E. Transverse section of a stichidium. F–J. Heterosiphonia wrangelioides (F–H, AD, A30631; I, AD, A27895; J, AD, A26944). F. Transverse sections of mature axes. G. Mature pseudolateral. H. A mature procarp. I. Spermatangial branches. J. Stichidia on a pseudolateral. (All as in Parsons 1975, courtesy of Aust. J. Bot.)

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