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Electronic Flora of South Australia Species Fact Sheet

Heterocladia australis Decaisne 1842: 359. (1841: 177, 178, pl. V figs 18–22, without specific name).

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Heterocladieae

Selected citations: J. Agardh 1863: 1250; 1897: 90, pl. 2 figs 6, 7? De Toni 1903: 1126. Falkenberg 1901: 588, pl. 12 figs 16–21. Harvey 1863, synop.: xviii. Hommersand 1863: 338. Kylin 1956: 556, fig. 443B. Lucas 1909: 47. May 1965: 399. Phillips et al. 2000: 203, figs 2–35. Schmitz 1889: 447. Schmitz & Falkenberg 1897: 454, fig. 255. Silva et al. 1996: 500. Sonder 1880: 33.


Heterocladia prohfera Decaisne ex Kützing 1849: 879, nom. illegit.; 1866: 3, pl. 7a-f.

Coeloclonium gracilipes J. Agardh 1897: 47.

Dolichoscelis gracilipes (J. Agardh) J. Agardh 1899: 120. De Toni 1903: 828. Falkenberg 1901: 215. Gordon-Mills & Womersley 1987: 561. Kylin 1956: 551. Lucas 1909: 40. Lucas & Perrin 1947: 257. May 1965: 383. Silva et al. 1996: 491.

Thallus (Fig. 123A) erect, medium to dark red-brown, (10–) 20–50 cm high, with a prominent, terete to slightly compressed main axis 1–3 (–5) mm broad, bearing irregularly but usually densely lateral branches 2–15 cm long with compressed lower parts 0.5–3 cm long and 2–6 (–14) mm broad, surmounted by terete, irregularly branched, upper parts 4–14 cm long, often profusely covered with trichoblasts. Holdfast discoid, 3–6 mm across, often fibrous; epilithic or on calcareous algae. Structure. Growth apical (Fig. 123B), monopodial, apical cell dome-shaped 30–40 µm in diameter (with thick walls), axial cells with 4 pericentral cells, rapidly and extensively corticated with rhizoidal filaments (Fig. 123D) from the pericentral and inner cells, pericentral cells soon obscured, inner cortical cells large, outermost small. Trichoblasts from each segment below apices, 1–3 mm long, branched from each lower cell with the walls adherent at each dichotomy, lower cells 30–55 µm in diameter and L/D 2–3, rhodoplastic. Cells multinucleate; rhodoplasts discoid, chained in larger cells.

Reproduction: Gametophytes dioecious. Procarps usually on the second cell of trichoblasts, the supporting cell bearing a 4-celled carpogonial branch and a sterile 3-celled group. Carposporophyte (Fig. 123E) with a basal fusion cell and a short, branched, gonimoblast with clavate terminal carposporangia 80–150 µm in diameter. Cystocarps stalked, ovoid, 1–2.5 mm in diameter; pericarp ostiolate, corticated, 4–5 cells thick. Spermatangial organs (Fig. 123C) on branches of trichoblasts, elongate-ovoid, 50–70 µm in diameter and 150–200 µm long, with 4 pericentral cells and a 3–4-celled sterile apex.

Tetrasporangia (Fig. 123F) borne in lesser, simple or compound, corticated, branches, bearing abundant trichoblasts, spirally arranged and single per tier, 150–270 µm in diameter.

Type from "cotes occidentale Nova Hollandiae" (Leschenault); holotype in PC.

Selected specimens: Geraldton, W. Aust., drift (G. & R. Kraft, 9.x.1990; MELU, K9985; AD, A67880). Eyre, W. Aust., drift (Gordon, 22.xi.1968; AD, A34227). El liston, S. Aust., drift (Womersley, 27.ii.1959; AD, A22221) and 25 m deep outside bar (Shepherd, 25.x.1971; AD, A42573). 3 km SE of Troubridge I., S. Aust., 24 m deep (Shepherd, 5.ii.1969; AD, A33890). Gulf St Vincent, S. Aust., 20 fathoms (40 m) deep (AD, A1224, A16141).

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

Distribution: Geraldton, W. Aust., to Gulf St Vincent, S. Australia.

Taxonomic notes: Heterocladia australis is a rare, deep-water alga most common in the Geraldton region of Western Australia. The unusual type specimen and the species morphology and variation have been discussed by Phillips et al. 2000, p. 203.


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

AGARDH, J.G. (1897). Analecta Algologica. Cont. IV. Acta Univ. lund. 33, 1–106, Plates 1, 2.

AGARDH, J.G. (1899). Analecta Algologica. Cont. V. Acta Univ. lund. 35, 1–160, Plates 1–3.

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

DECAISNE, J. (1841). Plantes de l'Arabie heureuse. Archs Mus. Hist. nat., Paris 2, 89–199, Plates 5–7.

DECAISNE, J. (1842). Essais sur une classification des Algues et des Polypiers calcifères de Lamouroux. Ann. Sci. Nat., 2 Sér. Bot., 17, 297–380, Plates 14–17.

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.)

GORDON-MILLS, E.M. & WOMERSLEY, H.B.S. (1987). The genus Chondria C. Agardh (Rhodomelaceae, Rhodophyta) in southern Australia. Aust. J. Bot. 35, 477–565.

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

KÜTZING, F.T. (1849). Species Algarum. (Leipzig.)

KYLIN, H. (1956). Die Gattungen der Rhodophyceen. (Gleerups: Lund.)

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.

PHILLIPS, L.E., CHOI, H.-G., SAUNDERS, G.W. & KRAFT, G.T. (2000). The morphology, Taxonomy and molecular phylogeny of Heterocladia and Trigenia (Rhodomelaceae, Rhodophyta), with delineation of the little-known tribe Heterocladieae. J. Phycol. 36, 199–219.

SCHMITZ, F. & FALKENBERG, P. (1897). Rhodomelaceae. In Engler, A. & Prantl, K., Die natürlichen Pflanzenfamilien. T.1. Abt. 2, pp. 421–480. (Englemann: Leipzig.)

SCHMITZ, F. (1889). Systematische Übersicht der bisher bekannten Gattungen der Florideen. Flora, Jena 72, 435–456, Plate 21.

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

SONDER, O.W. (1880). 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 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. 123.

Figure 123 image

Figure 123   enlarge

Fig. 123. Heterocladia australis (A, E, F, AD, A34227; B, D, AD, A42573; C, MELU, K9985, by L.E. Phillips). A. Habit. B. Apex with trichoblasts. C. Spermatangial organs on trichoblasts. D. Transverse section of branch. E. Cystocarp with carposporophyte. F. Branch with tetrasporangia and trichoblasts.

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