Electronic Flora of South Australia Species Fact Sheet
Phylum Phaeophyta – Order Ectocarpales
Selected citations: Cardinal 1964:45, fig. 23. Clayton 1974: 779, figs 21,22. King & Ducker 1971: 116. Kuckuck 1963: 374, figs 7,8. Womersley 1967: 193.
Ectocarpus mitchelliae Harvey 1852: 142, pl. 12G.
Thallus (Fig. 10D) medium to dark brown, loosely to densely tufted, (0.5–) 1–4 (–10) cm long, with the axes attached by a tuft of descending rhizoids from the lower cells, much branched (Fig. 12E) irregularly to spirally or tending to unilateral above; epilithic or epiphytic. Filaments (Fig. 12E,F) tapering gradually, 30–60 um in diameter below with cells L/B 1–2 (–2.5), mid branches 25–40 µm in diameter with cells L/B (0.7–) 1–1.6 (–2), lesser branchlets 20–30 µm in diameter with cells L/B (0.5–) 1–1.5, tapering into false hairs 8–20 µm in diameter with cells L/B 4–6. Growth from scattered meristematic regions along the main axes and meristems at the base of most branches, with further scattered intercalary divisions. Cells (Fig. 12F) with numerous discoid phaeoplasts each with a pyrenoid, and clustered physodes.
Reproduction: Plurilocular sporangia (Fig. 12E,F) scattered but often tending to be unilateral and adaxial, sessile, cylindrical and straight but usually tapering slightly to rounded ends, (50–) 60–140 µm long and 20–40 µm in diameter, L/B (2.5–) 4–6; sporangia with large or small locules reported (Clayton 1974, p. 779). Unilocular sporangia (Fig. 12G) on same plants as plurilocular sporangia, scattered, sessile, ovoid, 40–60 µm long and 16–27 Atm in diameter.
Type from Nantucket, Massachusetts, U.S.A.; in TCD.
Selected specimens: King Head, Rottnest I., W. Aust., low eulittoral on reef edge ( Womersley, 6.ix.1979; ADU, A50804). Middleton Beach, Albany, W. Aust., upper sublittoral on Amphibolis antarctica (Womersley, 29.viii.1979; ADU, A51379). Elliston, S. Aust., upper sublittoral on Codium galeatum (Parsons, 24.viii.1967; ADU, A31945). Cape Carnot, S. Aust. on Cystophora intermedia in pools (Womersley, 3.xii.1975; ADU, A46789-"Marine Algae of southern Australia" No. 171). Petrel Cove, Victor Harbor, S. Aust., upper sublittoral on rock ( Woelkerling, 15.vii.1968; ADU, A32619). Crawfish Rock, Westernport Bay, Vic., 2 m deep (Watson, 28.v.1974; ADU, A45373). Tesselated Pavement, Eaglehawk Neck, Tas., upper sublittoral pools (Parsons & Womersley, 30.x.1982; ADU, A545 l 7-"Marine Algae of southern Australia" No. 171a). Stingray Bay, Port Arthur, Tas. (Cribb 160.3, 16.x.1951; ADU, A21044).
Distribution: Widespread in temperate and subtropical seas.
In southern Australia, along the whole coast from (at least) Rottnest I., W. Aust. to southern Queensland and including Tasmania.
Taxonomic notes: G. mitchelliae is one of the commonest Ectocarpaceae along southern Australia, being found under strong wave action and also in fairly calm conditions. The plurilocular sporangia are distinctive, being straight and cylindrical but with tapering and rounded ends. Müller (1969) has reported anisogamy in European material, but only one size of plurilocular locules has been observed in Australian specimens and these are taken to be sporangial.
CARDINAL, A. (1964). Étude sur les Ectocarpacees de la Manche. Nova Hedwigia 15, 1–86, Figs. 1–41.
CLAYTON, M.N. (1974). Studies on the development, life history and taxonomy of the Ectocarpales (Phaeophyta) in southern Australia. Aust. J. Bot. 22, 743–813.
HAMEL, G. (1939b). Phéophycées de France. Fasc. V, pp. 337–432, i-xlvii. (Paris.)
HARVEY, W.H. (1852). Nereis Boreali-Americana. Part I. Melanospermae. (Smithsonian Inst.: Washington.)
KING, R.J. & DUCKER, S. (1971). In King, R.J., Black, J.H. & Ducker, S. Intertidal ecology of Port Phillip Bay, with systematic lists of plants and animals. 3. Flora of the intertidal region, pp. 112–128. Mem. Nat. Mus. Vic. 32, 93–128.
KUCKUCK, P. (1963). Herausgegeben von P. Kornmann. Ectocarpaceen-Studien VIII. Einige Arten aus warmen Meeren. Helgol. wiss. Meeresunters. 8, 361–382.
MÜLLER, D.G. (1969). Anisogamy in Giffordia (Ectocarpales). Naturwissenschaften 56, 220.
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.
Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
©Board of the Botanic Gardens and State Herbarium, Government of South Australia
Illustrations in Womersley Part II, 1997: FIGS 10D, 12 E–G.
Figure 10 enlarge
Fig. 10. A. Acinetospora crinita (ADU, A54824). B. Giffordia sordida (ADU, A55332). C. Giffordia sandriana on Posidonia (ADU, A42716). D. Giffordia mitchelliae on Cystophora intermedia (ADU, A46789). E. Giffordia granulosa (ADU, A39491).
Figure 12 enlarge
Fig. 12. A–D. Giffordia sandriana (A,C, ADU, A29269: B,D, ADU, A42716). A. Habit. B. Lateral with an adaxial series of plurilocular sporangia and young branchlets. C. Plurilocular sporangia in interrupted series. D. Unilocular sporangia. E–G. Giffordia mitchelliae (E,F, ADU, A31945; G, ADU, A21044). E. Habit, with plurilocular sporangia. F. Plurilocular sporangia. G. Unilocular and plurilocular sporangia.
State Herbarium of South Australia