Electronic Flora of South Australia Species Fact Sheet

Cystophora platylobium (Mertens) J. Agardh 1848: 245; 1896: 49.

Phylum Phaeophyta – Order Fucales – Family Cystoseiraceae

Selected citations: Harvey 1859b: 284. Lindauer et al. 1961: 297, pl. 69, right. Nizamuddin 1964c: 42–63. Womersley 1964: 68, fig. 3, pl. 1.


Fucus platylobium Mertens 1819: 182, pl. 14.

Thallus (Pl. 8 fig. 2; Fig. 133A) medium brown, robust, complanately branched, (0.5–) 1–2 (–4) m long, with a broad primary axis bearing strongly developed secondary axes and once pinnate laterals, with broad, flat, ramuli. Holdfast discoid-conical, 0.5–2 cm across, with a single, short, terete stipe 2–5 mm in diameter; epilithic. Primary axes strongly compressed, (0.3–) 0.5–1 (–1.5) cm broad and 2–4 (–5) mm thick centrally, often slightly flexuous, alternately distichously branched from the edges; secondary axes developing in the axils of most laterals, not or slightly retroflex, of slightly less dimensions than primary axes. Laterals (Fig. 136A) mostly 10–15 cm long, complanate, alternately distichous with simple, broadly lanceolate, ramuli 0.5–4 cm long and 2–10 mm broad, costate, basally constricted and tapering to an apiculate to rounded apex; laterals usually lost below, with short, stubby residues. Vesicles

(Fig. 136A) usually present, replacing the basal ramulus of occasional laterals, spherical to slightly ovoid, 5–15 mm in diameter, mutic.

Reproduction: Thalli monoecious. Receptacles (Fig. 136A) simple, 1–3 cm long and 3–8 (–10) mm broad, lanceolate to elliptic-lanceolate, basally stalked. Conceptacles (Fig. 132H) elongate transversely to the receptacles, with ostioles on the margins, bisexual; oogonia sessile, ovoid, 80–160 µm long and 70–100 µm in diameter, with a single egg; antheridia on branched paraphyses, elongate-ovoid, 20–25 µm long and 10–15 µ in diameter; simple, slender, paraphyses present.

Type from "Novae Hollandiae littora"; in PC.

Selected specimens: 16 km E. of Eucla, S. Aust., drift ( Womersley, 3.ii.1954; ADU, A19251). Pearson I., S. Aust., 48 m deep (Shepherd, 9.i.1969; ADU, A33708). Thistle I., S. Aust., 16 m deep (Baldock, 2.i.1964; ADU, A27175). Althrope I., southern Spencer Gulf, S. Aust., 18 m deep (Retallick, 3.iii.1987; ADU, A57434). Port Elliot, S. Aust., drift (Womersley, 16.viii.1961; ADU, A26865). Vivonne Bay, Kangaroo I., S. Aust., drift (Womersley, 3.i.1946; ADU, A3356). 22 km N.W. of Robe, S. Aust., 40 m deep (Shepherd, 20.xi.1968; ADU, A33093). Robe, S. Aust., drift (Womersley, 16.xii.1986; ADU, A57321-"Marine Algae of southern Australia" No. 279). Lawrence Rock, Portland, Vic., 8–11 m deep (Watson, 2.ix.1971; ADU, A39686). Walkerville, Vic., drift (Sinkora A1582, 23.ii.-9.iii.1972; ADU, A43102). Low Head, Tas., 4–12 m deep (Perrin, Aug. 1948; ADU, A9327). Lady Bay, Southport, Tas., 0–1 m deep (Womersley, 28.x.1982; ADU, A56511).

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

Distribution: From 16 km E. of Eucla, S. Aust. around south-eastern Australia and Tasmania to Bondi, N.S.W.

New Zealand.

Taxonomic notes: C. platylobium is a distinctive species, common but largely confined to deep water (10–48 m deep) on rough-water coasts in south-eastern Australia, though found in shallower water (up to 1 m deep) in south-east Tasmania.


AGARDH, J.G. (1848). Species, Genera et Ordines Algarum. Vol. 1. (Gleerup: Lund.)

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

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. Part III. Flora Tasmaniae. Vol. 2, pp. 282–343, Plates 185–196.

LINDAUER, V.W., CHAPMAN, V.J. & AIKEN, M. (1961). The marine algae of New Zealand. II. Phaeophyceae. Nova Hedwigia 3, 129–350, Plates 57–97.

MERTENS, M. (1819). Sur plusieurs espêces de Fucus, nouvelles ou peu connues, observées dans la collection du Muséum. Mem. Mus. Natl Hist. Nat., Paris 5, 172–90, Plates 13–15.

NIZAMUDDIN, M. (1964c). The anatomy and life history of Cystophora, Acrocarpia and Caulocystis (Fucales). Bot. Mar. 7, 42–63.

WOMERSLEY, H.B.S. (1964). The morphology and taxonomy of Cystophora and related genera (Phaeophyta). Aust. J. Bot. 12, 53–110, Plates 1–16.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustrations in Womersley Part II, 1997: PLATE 8 fig. 2; FIGS 132H, 133A, 136A.

Plate 8 image

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PLATE 8 fig. 1. Caulocystis cephalornithos. A rock pool plant photographed on rock, Robe, S. Aust.
fig. 2. Cystophora platylobium 18 m deep off Althorpe I., S. Aust. (ADU, A57434) (Photo: M. Retallick).
fig. 3. Cystophora siliquosa at Point Avoid, S. Aust. (ADU, A57372).
fig. 4. Sargassum fallax. An upper sublittoral plant photographed on rock, Robe, S. Aust.

Figure 132 image

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Fig. 132. A,B. Caulocystis cephalornithos (A, ADU, A26881; B, ADU, A57286). A. Terminal branches and receptacles. B. Cross section of receptacle with bisexual conceptacles. C,D. Acrocarpia paniculata ( C, ADU, A26801; D, ADU, A57342). C. Terminal branch with receptacles. D. Cross section of receptacle with bisexual conceptacles. E–G. Acrocarpia robusta (E,F, ADU, A26473; G, ADU, A50547). E. Branch with bifurcate ramuli. F. Branch with receptacles. G. Cross section of receptacle with bisexual conceptacles each with a central columella. H. Cystophora platylobium (ADU, A57321). Cross section of receptacle with elongate, bisexual, conceptacles. I. Cystophora retroflexa (ADU, A57386). Cross section of receptacle with bisexual conceptacles.

Figure 133 image

Figure 133   enlarge

Fig. 133. A. Cystophora platylobium (ADU, A3356). B. Cystophora monihformis (ADU, A57322).

Figure 136 image

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Fig. 136. Receptacles of species of Cystophora. A. Cystophora platylobium (ADU, A26865). B. Cystophora moniliformis (ADU, A18823). C. Cystophora intermedia (ADU, A26800). D. Cystophora intermedia (ADU, A3462). E. Cystophora grevillei (ADU, A26752), axis with laterals and vesicles. F. Cystophora grevillei (ADU, A5713), receptacles. G. Cystophora xiphocarpa (ADU, A19808), axis with simple laterals.

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