Electronic Flora of South Australia Species Fact Sheet

Ectocarpus siliculosus (Dillwyn) Lyngbye 1819: 131, pl. 43B,C.

Phylum Phaeophyta – Order Ectocarpales

Selected citations: Abbott & Hollenberg 1976: 128, fig. 90. Hamel 1931: 21, fig. 3. Harvey 1848: pl. 162. Milner 1967: 39; 1979: 312. Russell 1966: 275, figs 3,4. Womersley 1967: 190.

Synonym

E. confervoides (Roth) Le Jolis. Cardinal 1964: 14, figs 2–5. Hamel 1931: 23, fig. 4. Rosenvinge & Lund 1941: 14, figs 1–5.

Thallus (Fig. 2D) medium brown, 1–25 cm long, much and irregularly branched from the base with laterals throughout (Fig. 5A), older branches often subdichotomous, sometimes secund above but not with fasciculate lateral branch systems, attached by rhizoids from lower cells; epiphytic or epilithic, occasionally free-floating. Branches tapering gradually from the base, normally into long false hairs (Fig. 5B) with few phaeoplasts and without a basal meristem. Lower filaments 20–38 (–45) µm in diameter, cells L/B (0.5–) 1–2; branchlets 10–15 µm in diameter, cells L/B (0.5–) 1–2; false hairs 8–12 (–16) µm in diameter. Growth diffuse. Cells with several elongate or ribbon-like, simple or branched and usually relatively broad phaeoplasts, each with several pyrenoids (Fig. 5C–E).

Reproduction: Reproduction by pedicellate or occasionally sessile plurilocular sporangia (or gametangia?) scattered on the branchlets, elongate-conical (Fig. 5C,D) to narrow-linear (Fig. 5E) and sometimes surmounted by a hair, apically tapering or broader in their centre, 70–160 µm long and (12–) 20–35 (–50) µm in diameter; some plants also bearing ovoid to subspherical, sessile or pedicellate unilocular sporangia, (18–) 25–38 µm in diameter (Fig. 5D).

Type from England; in K(BM)?

Selected specimens: Point Valliant, Two People Bay, W. Aust., mid eulittoral pool (Womersley, 30.viii.1979; ADU, A50976). Wanna, Port Lincoln, S. Aust., lower eulittoral (Womersley, 21.viii.1967; ADU, A31858-"Marine Algae of southern Australia" No. 29). Pennington Bay, Kangaroo I., S. Aust., lower eulittoral (Womersley, 28.vii.1947; ADU, A5794). Petrel Cove, Victor Harbor, S. Aust., mid eulittoral pools (Womersley, 10.x.1983; ADU, A54422). N.W. of Bluff, Victor Harbor, S. Aust., mid eulittoral pools (Clarke, 23.vi.1983; ADU, A54169). Point Roadknight, Vic., low eulittoral pools (Womersley 11.iv.1959; ADU, A22595). Apollo Bay, Vic., on Scytosiphon, mid eulittoral pools ( Womersley, 31.viii.1971; ADU, A39482-"Marine Algae of southern Australia" No. 148). Southport, Tas., drift (Gordon, 14.i.1966; ADU, A30020).


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

Distribution: Widely distributed in temperate and tropical seas, usually in the intertidal or uppermost sublittoral.

In southern Australia, along the whole coast from Rottnest I. (probably further north), W. Aust., through Victoria and Tasmania, into N.S.W. and to southern Queensland. E. siliculosus is characteristically a winter species (often replaced by Bachelotia in summer) with occasional specimens in other seasons.

Taxonomic notes: Ectocarpus siliculosus is a common winter species in both rough-water and sheltered conditions. Typically the branchlets taper gradually into long false hairs, but in some, apparently young, plants such hair endings are not developed. The plurilocular sporangia vary greatly in proportions between different collections.

References:

ABBOTT, I.A. & HOLLENBERG, G.J. (1976). Marine Algae of California. (Stanford Univ. Press: Stanford.)

CARDINAL, A. (1964). Étude sur les Ectocarpacees de la Manche. Nova Hedwigia 15, 1–86, Figs. 1–41.

HAMEL, G. (1931). Phéophycées de France. Fasc. I, pp. 1–80. (Paris.)

HARVEY, W.H. (1848). Phycologia Britannica. Plates 145–216. (Reeve: London.)

LYNGBYE, H.CH. (1819). Tentamen Hydrophytologiae Danicae. (Copenhagen.) McCULLY, M.E. (1966). Histological studies on the genus Fucus I. Light microscopy of the mature vegetative plant. Protoplasma 62, 287–305, Fig. 1. MacLENNAN, I.G. (1956). A brown alga (Petrospongium rugosum) new to Victoria. Proc. R. Soc. Vict. 69, 1–3.

ROSENVINGE, L.K. & LUND, S. (1941). The marine algae of Denmark. Vol. II. Phaeophyceae. I. Ectocarpaceae and Acinetosporaceae. K. Dan. Vidensk. Selsk. Biol. Skr. 1(4), 1–79.

RUSSELL, G. (1966). The genus Ectocarpus in Britain. I. The attached forms. J. mar. biol. Ass. U.K. 46, 267–294.

WOMERSLEY, H.B.S. (1967). A critical survey of the marine algae of southern Australia. II. Phaeophyta. Aust. J. Bot. 15, 189–270.

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: FIGS 2D, 5 A–E.

Figure 2 image

Figure 2   enlarge

Fig. 2. A. Asteronema ferruginea on Hormosira (ADU, A52853). B. Bachelotia antillarum (ADU, A49210). C. Kuckuckia spinosa on Amphibolis (ADU, A39457). D. Ectocarpus siliculosus (ADU, A54422). E. Ectocarpus fasciculatus on Ecklonia (ADU, A32006).

Figure 5 image

Figure 5   enlarge

Fig. 5. A–E. Ectocarpus siliculosus (A–C, ADU, A54422; D, ADU, A54169; E, ADU, A30020). A. Branching pattern. B. Branches with false hairs and plurilocular sporangia. C. Cells and plurilocular sporangia. D. Branch with plurilocular and unilocular sporangia. E. Plurilocular sporangia, one with a slight hair. F–H. Ectocarpus fasciculatus (ADU, A31777). F. Branching pattern. G. Branch with laterals and plurilocular sporangia. H. Cells and plurilocular sporangia.


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