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Heterocladia caudata Phillips, Choi, Saunders & Kraft 2000: 218.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Heterocladieae


Trigenia australis Sonder 1845: 54; 1848: 181; 1880: 33. J. Agardh 1863: 1248; 1890: 116; 1894: 83–87; 1899: 122. De Toni 1903: 1124. Falkenberg 1901: 583. Harvey 1847: 37; 1855a: 538. Hommersand 1963: 338. Kützing 1849: 841; 1866: 20, pl. 57a-e. Kylin 1956: 556. Lucas 1909: 47. Lucas & Perrin 1947: 305 (in part). May 1965: 384. Phillips et al. 2000: 208, figs 36–52. Schmitz 1889: 446. Schmitz & Falkenberg 1897: 454. Silva et al. 1996: 555. Tate 1882a: 22. Tisdall 1898: 513.

Rhodomela trigenia Harvey 1860: pl. 126; 1863, synop.: xviii. Tisdall 1898: 513.

Thallus (Fig. 124A) dark red-brown, erect, 20–60 cm high, with a terete to slightly compressed main axis bearing a few similar main lateral branches 5–20 cm long, all bearing a dense cover of terete, determinate, simple or occasionally branched, laterals 0.5–1.5 cm long and 300–500 µm in diameter, some bearing trichoblasts; axes denuded below, cartilaginous, 2–5 mm in diameter. Holdfast discoid with fibrous outgrowths, 2–10 mm across; epilithic. Structure. Apices tapering, apical cell dome-shaped, thick walled, axial cells cutting off 4 pericentral cells, rapidly corticated and producing abundant rhizoidal filaments from inner cells obscuring the pericentral cells; older axes have a medulla largely of entangled rhizoids (Fig. 124B) with a thin outer cortex of small cells. Trichoblasts are produced apically from each segment, 300–900 µm long, below branched 2 cells apart with adherent walls at the branchings, lower cells 35–70 µm in diameter and L/D mostly 1–1.5, rhodoplastic. Cells uni- or multinucleate; rhodoplasts discoid to elongate.

Reproduction: Procarps usually on the second cell of trichoblasts, with the supporting cell bearing a 4-celled carpogonial branch and a sterile group of 3 cells. Carposporophytes with a basal fusion cell and a short, branched, gonimoblast with clavate terminal carposporangia 50–150 µm in diameter. Cystocarps stalked or subsessile, ovoid, 800–1200 µm in diameter; pericarp ostiolate, corticated, 4–5 cells thick. Spermatangia unknown.

Tetrasporangia (Fig. 124C) borne in simple or branched, corticated, determinate laterals bearing trichoblasts, spirally arranged, single per tier, 120–250 µm in diameter.

Type from "occid. Novae Hollandiae"; holotype in MEL, 537394.

Selected specimens: Geraldton, W. Aust., drift (Kraft & Herrington, 9.x.1990; MELU, K9984). Port Denison, W. Aust., drift (Kraft 3971, 14.xii.1971; MELU and AD, A41738), and (Woelkerling, 8.xi.1968; AD, A33214). Cliff Head, W. Aust., drift (Womersley, 18.ix.1979; AD, A51231). Hopetoun, W. Aust., drift (Gordon, 20.xi.1968; AD, A34169).

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

Distribution: Geraldton to Hopetoun, W. Australia. Auckland Is? (Papenfuss 1964b: 64).

Taxonomic notes: Heterocladia caudata is only known from drift specimens and appears to be largely restricted to the west coast of Australia; the Hopetoun specimen may have been transported in an easterly current from the west coast.

Many specimens of H. umbellifera have been misidentified as Trigenia australis (H. caudata), and any of the references to T. australis referring to localities east of Western Australia are probably incorrect. Some Kangaroo I. specimens in AD had been tentatively identified as T. australis but are now referred to H. umbellifera. True H. caudata appears to not occur east of Hopetoun, W. Australia.


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

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

AGARDH, J.G. (1894). Analecta Algologica. Cont. II. Acta Univ. lund. 30, 1–98, Plate 1.

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.)

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. (1847). Nereis Australis, pp. 1–69, Plates 1–25. (Reeve: London.)

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. (1860). Phycologia Australica. Vol. 3, Plates 121–180. (Reeve: London.)

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

HOMMERSAND, M.H. (1963). The morphology and classification of some Ceramiaceae and Rhodomelaceae. Univ. Calif. Pubis. Bot. 35(2), 165–366.

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

KÜTZING, F.T. (1866). Tabulae Phycologicae. Vol. 16. (Nordhausen.)

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.

PAPENFUSS, G.F. (1964b). Catalogue and bibliography of antarctic and subantarctic benthic marine algae. Am. geophys. Un. Antarctic Res. Ser., Vol. 1, pp. 1–76.

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.G. (1845). Nova Algarum genera et species, quas in itinere ad oras occidentales Novae Hollandiae, collegit L. Preiss, Ph.Dr. Bot. Zeit. 3, 49–57.

SONDER, O.W. (1848). Algae. In Lehmann, C., Plantae Preissianae. Vol. 2, pp. 161–195. (Hamburg.)

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

TATE, R. (1882a). A list of the charas, mosses, liverworts, lichens, fungs, and algals of extratropical South Australia. Trans. R. Soc. S. Aust. 4, 5–24.

TISDALL, H.T. (1898). The algae of Victoria. Rep. 7th Meet. Aust. Ass. Adv. Sci., Sydney, 1898, pp. 493–516.

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. 124 A–C.

Figure 124 image

Figure 124   enlarge

Fig. 124. A–C. Heterocladia caudata (A, AD, A34169; B, C, AD, A33214). A. Habit. B. Transverse section of branch and tetrasporangial branch. C. Branch with tetrasporangia and trichoblasts. D, E, Heterocladia umbellifera (AD, A68393). D. Habit. E. Transverse section of young branch.

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