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Electronic Flora of South Australia Species Fact Sheet

Rhodymenia cuneata Harvey 1859b: 319; 1863: pl. 295.

Phylum Rhodophyta – Class Florideophyceae – Order Rhodymeniales – Family Rhodymeniaceae

Selected citations: Sonder 1881: 18. Epymenia ?cuneata (Harvey) J. Agardh 1892: 91. De Toni 1900b: 526. Guiler 1952: 94. Lucas 1929a: 18. May 1965: 407. Sparling 1957: 348.

Thallus (Fig. 32A) medium to dark red-brown, fading to grey-red, 4–20 cm high, foliose and usually divided above into several lobes 1–8 cm across, membranous to cartilaginous, surface smooth and without proliferations, (150–) 200–350 µm thick, with a slender, terete to compressed, stipe 4–15 mm long tapering to a narrowly to broadly cuneate frond base. Holdfast discoid, 1–3 mm across, with 1–2 fronds; epilithic or on the mollusc Maoricolpus. Structure multiaxial, developing a cortex 1–2 cells thick (Fig. 32B), outer cells rounded and 5–8 µm in diameter (forming slight rosettes in surface view), grading sharply to the medulla mostly 2 cells broad when young, cells ovoid, 90–140 µm in diameter, walls (3–) 5–10 µm thick with occasional intercellular spaces or smaller cells between larger cells; medulla becoming 8–12 cells and 600–800 µm broad near and in the stipe, stipe 0.6–1.2 mm in diameter with some secondary cortical development. Rhodoplasts discoid to elongate, becoming ribbon like or reticulate.

Reproduction: Gametangial thalli probably dioecious. Carpogonial branches not observed; auxiliary cell terminating a 2-celled branch on the supporting cell, with a globular inclusion. Carposporophyte (Fig. 32C) dendroid, with an erect branched fusion cell(s) and closely adjacent lobes forming a dense subspherical to ovoid mass of carposporangia 350–600 µm across; all cells forming angular to ovoid carposporangia 10–14 µm across. Basal nutritive tissue relatively slight, erect filaments disintegrating apart from remnant stellate cells. Cystocarps (Fig. 32C) sessile, broad-based (not or slightly constricted), 1.0–1.6 mm across; pericarp 200–300 µm and 10–15 cells thick, ostiolate. Spermatangia unknown.

Tetrasporangia unknown.

Type from East coast, Tas. (Gunn); holotype in Herb. Harvey, TCD.

Selected specimens: Musselroe Bay, Tas. (Perrin & Lucas, March 1936; NSW, 10607, 10608). Sloping I., Frederick Henry Bay, Tas., 12 m deep (AIMS-NCI, Q66C 5024-A, 12.ii.1991; AD, A61375). 2 km N of Satellite I., D'Entrecasteaux Ch., Tas., 15 m deep (Shepherd, 17.ii.1972; AD, A41667). Simpson Bay, Bruny I., Tas., 11 m deep (Shepherd, 11.ii.1972; AD, A41596). Great Taylor Bay, Bruny I., Tas., 10 m deep (Shepherd, 7.ii.1970; AD, A35288) and 19 m deep (Shepherd, 14.ii.1972; AD, A42162). Sarah I., Bathurst Ch., SW Tas., 2–5 m deep (Edgar, 11.iii.1995; AD, A64252).

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

Distribution: East and SE Tasmania.

Taxonomic notes: R. cuneata is distinctive in habit and in cross section with mostly two large, relatively thick-walled medullary cells. The outer cortical cells mostly form slight rosettes around the next inner cells.

Further studies are needed, especially of male and tetrasporangial plants.

Excluded or doubtful species

Rhodymenia corallina (Bory) Greville (1830: xlviii), from South America [type from Chile (Binder); lectotype in Herb. Bornet, PC].

Harvey (1859b, p. 319) first ascribed Australian specimens to R. corallina (followed by several other authors) but later (1863, synop.: xl) referred them to his R. foliifera. The lectotype of R. corallina in PC agrees well with the figure of Bory (1828, pl. 16). It is a large plant, about 20 cm high, with a distinct stipe 3–4 cm long, broadening to branches nearly 1 cm broad, then tapering fairly evenly to the apices 2–4 mm broad. While some specimens placed in R. australis approach this, they are generally slenderer plants and for the present it seems best to exclude R. corallina from the southern Australian flora.

Rhodymenia linearis J. Agardh (1841: 13) was originally recorded from "mari australi; misit Hoffman-Bang". Both the locality and the collector are thus unknown. The type sheet (Herb. Agardh, LD, 26970, see Kylin 1931: 20, pl. 6 fig. 16) has relatively linear, subdichotomous branches 2–3 (–4) mm broad, bearing scattered, conical, external cystocarps over most of the branches. One other specimen (26969) from "East coast of New Zealand" in Herb. Agardh is similar in habit, and the species is considered in the New Zealand flora by Chapman & Dromgoole (1970, p. 133, pl. 43, upper). R. linearis was credited to "Coast of New Holland" and Tasmania by Sonder (1881, p. 18), Dawson (1941, p. 137) and others but no Australian specimens agree well with the type and it is more likely a New Zealand species only.


AGARDH, J.G. (1841). In historiam algarum symbolae. Linnaea 15, 1–50, 443–457.

AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.

BORY DE ST-VINCENT, J.B. (1828). In Duperrey, L.I., Voyage autour du monde, exécuté par ordre du Roi, sur la corvette de Sa Majesté, la Coquille, pendant les années 1822, 1823, 1824 et 1825. Botanique, Cryptogamie, pp. 1–300, Plates 1–39. (Bertrand: Paris.)

CHAPMAN, V.J. & DROMGOOLE, F.I. (1970). The marine algae of New Zealand, Part III: Rhodophyceae. Issue 2: Florideophycidae: Rhodyméniales, pp. 115–154, Plates 39–50. (Cramer: Germany.)

DAWSON, E.Y. (1941). A review of the genus Rhodymenia with descriptions of new species. Allan Hancock Pacif. Exped. 3(7), 115–181.

DE TONI, G.B. (1900b). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 2, pp. 387–776. (Padua.)

GREVILLE, R.K. (1830). Algae Britannicae. (Maclachlan & Stewart: Edinburgh.)

GUILER, E.R. (1952). The marine algae of Tasmania. Check List with localities. Pap. Proc. R. Soc. Tasm. 86, 71–106.

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. HI Flora Tasmaniae. Vol. II, pp. 282–320. (Reeve: London.)

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

KYLIN, H. (1931). Die Florideenordnung Rhodyméniales. Lunds Univ. Årsskr. N.F. Avd. 2, 27 (11), 1–48, Plates 1–20.

LUCAS, A.H.S. (1929a). The marine algae of Tasmania. Pap. Proc. R. Soc. Tasm. 1928, 6–27.

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.

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

SPARLING, S.R. (1957). The structure and reproduction of some members of the Rhodymeniaceae. Univ. Calif Pubis Bot. 29, 319–396.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (28 June, 1996)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIB. Gracilarialse, Rhodymeniales, Corallinales and Bonnemaisoniales
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIB 1996, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustration in Womersley Part IIIA, 1996: FIG. 32.

Figure 32 image

Figure 32   enlarge

Fig. 32. Rhodymenia cuneata (AD, A61375). A. Habit. B. Transverse section of thallus. C. Section of cystocarp.

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