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Coelarthrum opuntia (Endlicher) Børgesen 1937: 333, figs 9, 10.

Phylum Rhodophyta – Class Florideophyceae – Order Rhodymeniales – Family Rhodymeniaceae

Selected citations: Huisman 1996: 100, figs 16–25.


Chondria opuntia J. Agardh 1841: 21 (nom. illegit. – see Huisman 1996: 103).

Chrysymenia opuntia Endlicher 1843: 42.

Lomentaria opuntia (J. Agardh) J. Agardh 1852: 737. Kylin 1931: 33, pl. 20 fig. 48.

Lomentaria muelleri Sonder 1853: 693.

Chylocladia muelleri (Sonder) Harvey 1860: pl. 138. J. Agardh 1876: 302. Sonder 1881: 17. Tisdall 1898: 506. Wilson 1892: 180.

Erythrocolon muelleri (Sonder) J. Agardh 1896: 91. Biswas 1945: 529, pl. 11 fig. 6. De Toni 1900b: 585. Lucas & Perrin 1947: 208, fig. 73.

Coelarthrum muelleri (Sonder) Børgesen 1931: 9, figs 6, 7. Huisman 1993: 16. Kylin 1931: 15. May 1965: 361. Womersley 1950: 175.

Lomentaria valida Kützing 1865: 30, pl. 85a, b.

Chylocladia ?valida (Kützing) J. Agardh 1890: 24. Reinbold 1897: 53.

Thallus (Fig. 18A) medium red to dark red-brown, (5–) 10–30 cm high, much branched with even-topped branches of similar height (growth usually synchronous), branches segmented with slender constrictions mostly 0.5–1 mm long and ovoid to elongate, hollow, segments bearing (1–) 2–4 branches from the apex of most segments; mature segments increasing in length below, 0.5–3 (–4) cm long and 2–7 mm in diameter, lowest segments (stipe) terete, 1–2 mm in diameter. Holdfast crustose and thick, 2–10 mm across, bearing one to several fronds; epilithic. Structure multiaxial, with a cortex 30–50 µm and 2–3 cells thick, outer cells laxly arranged, often in slight rosettes, ovoid and 5–8 (–10) µm in diameter, and a large-celled medulla 1–2 cells thick bordering the central weakly mucilaginous cavity, with the inner cells ovoid and 50–100 (–220) µm in diameter, walls 4–10 µm thick, with frequent secondary pit-connections and bearing 1–3 ovoid or pyriform secretory cells (Fig. 18C) 20–30 µm in diameter, on cells on the inner medullary cells; long surface hairs frequent. Constrictions with pseudoparenchymatous partitions 6–12 cells thick, of large and small cells intermixed with a cluster of secretory cells borne on the upper side of the partition (Fig. 18B). Rhodoplasts discoid to elongate, in chains or ribbon like in inner cells.

Reproduction: Gametangial thalli dioecious. Carpogonial branches 4-celled, borne on mid cortical cells; auxiliary cell branches 2-celled, auxiliary cell with a large, globular inclusion. Carposporophyte (Fig. 18D) with a basal fusion cell and all gonimoblast cells becoming ovoid to angular carposporangia 20–30 µm in diameter. Basal nutritive tissue moderate, erect filaments disintegrating but walls of lower cells remaining. Cystocarps scattered, external, 1–1.5 mm in basal diameter, conical to hemispherical and often beaked around the ostiole; pericarp 130–220 µm and 6–12 cells thick, cells laxly arranged, ostiolate. Spermatangia (Fig. 18E) in son, cut off from outer cortical cells, ovoid, 3–4 µm in diameter.

Tetrasporangia (Fig. 18F) scattered, transformed from inner cortical intercalary cells, subspherical to ovoid and 25–50 (–55) µm in diameter, decussately divided.

Type from the Indian Ocean; lectotype in Herb. Agardh, LD, 36065.

Selected specimens: Port Denison, W. Aust., drift (Kraft 4127, 14.xii.1971; AD, A41792). Esperance, W. Aust., drift (Firman, Dec. 1952; AD, A18947). Egg I., Isles of St Francis, S. Aust., 35 m deep (Shepherd, 7.i.1971; AD, A38098). N Spencer Gulf, S. Aust., 9 m deep (Shepherd, 13.ix.1973; AD, A44182). Wallaroo, S. Aust., 0.5–2.5 m deep (Gill, 9.xi.1980; AD, A51898). Stenhouse Bay, S. Aust., 7 m deep (Gilbert, 15.x.1988; AD, A59188). Edithburg, S. Aust., 3–4 m deep (Gowlett-Holmes, 9.ix.1995; AD, A64473). Investigator Strait, S. Aust., 26 m deep (Watson, 28.i.1971; AD, A38526). Marino, S. Aust., drift (Womersley, 26.x.1975; AD, A46643). Port Noarlunga, S. Aust., 24 m deep offshore (Ottaway, 3.ii.1981; AD, A52095). Kingscote, Kangaroo I., S. Aust., 1–2 m deep (Latz, 29.xi.1968; AD, A33001). Vivonne Bay, Kangaroo I., S. Aust., 3–4 m deep (Latz, 22.xi.1968; AD, A33018). Nora Creina, S. Aust., drift (Womersley, 4.x.1970; AD, A37342). Walkerville, Vic., drift (Sinkora A2550, 10.iii.1979; AD, A60969). Currie R., Tas. (Perrin, April 1935; AD, A49704).

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

Distribution: North Indian Ocean (see Huisman 1996).

Darwin, N.T., around western and southern Australia to Walkerville, Vic., and the N coast of Tasmania.

Taxonomic notes: C. muelleri has been shown by Huisman (1996) to be not specifically distinct from C. opuntia (Endlicher) Børgesen.

Lomentaria valida Kützing was described from Tasmania. However, what appears to be the type in L, 941, 149 ... 246 is from Lefevre Pen., S. Aust., Dec. 16, 1947 (probably a Mueller collection).


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

AGARDH, J.G. (1852). Species Genera et Ordines Algarum. Vol. 2, Part 2, pp. 337–720. (Gleerup: Lund.)

AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 — Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)

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

AGARDH, J.G. (1896). Analecta Algologica. Cont. III. Acta Univ. lund. 32, 1–140, Plate 1.

BØRGESEN, F. (1931). Some Indian Rhodophyceae especially from the shores of the Presidency of Bombay. Kew Bull. 1931(1), 1–24, Plates I, II.

BØRGESEN, F. (1937). Contributions to a South Indian marine algal flora - II. J. Indian Bot. Soc. 16, 311–357.

BISWAS, K. (1945). A general review of the marine algae of the western coast of India. J. Bombay Nat. Hist. Soc. 45, 515–530, plates I–III.

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

ENDLICHER, S.L. (1843). Genera plantarum secundum ordines naturales disposita. Suppl. 3 (Beck: Wien.)

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

HUISMAN, J.M. (1993). Supplement to the catalogue of marine plants recorded from Rottnest Island. In Wells, F.E., Walker, D.I., Kirkman, H. & Lethbridge, R. (Eds). The marine flora and fauna of Rottnest Island, Western Australia. Proc. Fifth Int. Mar. Biol. Workshop, pp. 11–18. (Western Australian Museum: Perth.)

HUISMAN, J.M. (1996). The red algal genus Coelarthrum. Børgesen (Rhodymeniaceae, Rhodyméniales) in Australian waters. Phycologia 35, 95–112.

KÜTZING, F.T. (1865). Tabulae Phycologicae. Vol. 15. (Nordhausen.)

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

LUCAS, A.H.S. & PERRIN, F. (1947). The Seaweeds of South Australia. Part 2. The Red Seaweeds. (Govt Printer: Adelaide.)

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.

REINBOLD, T. (1897). Die Algen der Lacepede und Guichen Bay und deren näherer Umgebung (Süd Australien), gesammelt von Dr. A. Engelhart-Kingston. Nuova Notarisia 8, 41–62.

SONDER, O.W. (1853). Plantae Muellerianae. Algae. Linnaea 25, 657–709.

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

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

WILSON, J.B. (1892). Catalogue of algae collected at or near Port Phillip Heads and Western Port. Proc. R. Soc. Vict. 4, 157–190.

WOMERSLEY, H.B.S. (1950). The marine algae of Kangaroo Island. III. List of Species 1. Trans. R. Soc. S. Aust. 73, 137–197.

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.

Illustrations in Womersley Part IIIA, 1996: PLATE 1 fig. 3; FIG. 18.

Plate 1 image

Plate 1   enlarge

figure 1. Gracilaria ramulosa (AD A63002). Photograph - H.B.S. Womersley.
figure 2. Cordylecladia furcellata (AD, A64395). Photograph - G. Edgar.
figure 3. Coelarthrum opuntia (AD, A64473). Photograph - K.L. Gowlett-Holmes.
figure 4. Rhodymenia leptophylla (AD, A64238). Photograph - G. Edgar.

Figure 18 image

Figure 18   enlarge

Fig. 18. Coelarthrum opuntia (A–C, E, F, AD, A46643; D, AD, A52095). A. Habit. B. Longitudinal section of a diaphragm with cluster of secretory cells on upper side. C. Filaments with secretory cells on inside of medullary cells. D. Section of cystocarp. E. Longitudinal section of spermatangial thallus. F. Section of tetrasporangial thallus.

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