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Taonia australasica J. Agardh 1894a: 30.

Phylum Phaeophyta – Order Dictyotales – Family Dictyotaceae – Tribe Zonarieae

Selected citations: Allender & Kraft 1983; 91, figs 9E–I, 10A,B. Womersley 1967: 223.

Thallus (Fig. 82B) light to medium brown, 5–15 (–20) cm long, complanate, flabellate when young, soon becoming lacerate and usually multifid, with a matted rhizoidal holdfast 1–7 mm across and 1–4 mm long; epilithic. Growth by an extensive marginal row of apical cells (Fig. 84A) in a usually convex apex. Fronds much branched in a subdichotomous to lateral manner by splitting, with no or few laterals from below, branches broadening upwards, 1–4 (–6) mm broad at their base, (1–) 2–6 (–20) mm broad at their apices. Structure 2 cells (Fig. 84B) and 60–100 thick in young parts, becoming (2–) 4 (–5) cells and 120–200 µm thick in older parts (Fig. 84C,D), margins slightly broader, with the outer cells the same size as inner cells in transverse section; cortical cells 20–30 (–35) µm across in surface view, L/B I -2 (–4). Hairs (Fig. 84A,D) forming more or less prominent concentric lines across the thallus, coinciding on both sides; hairs 14–24 Atm in diameter.

Reproduction: Sporangia (Fig. 84C,D) scattered, external to the blade, with 1–3 stalk cells, 110–140 µm in diameter, dividing tetrahedrally. Sexual reproduction unknown.

Type from Port Phillip Heads, Vic. (Wilson); in Herb. Agardh, LD, 48296.

Selected specimens: Cape du Couedic, Kangaroo I., S. Aust., drift (Womersley, 12.i.1948: ADU, A8252). E. side of Ballast Head, Kangaroo I., S. Aust., uppermost sublittoral (Womersley, 31.x. 1947; ADU, A6101). Christies Beach, S. Aust., 8 m deep, 4 m W. of effluent outfall (Clarke & Engler, 14.ii.1980; ADU, A50866-"Marine Algae of southern Australia" No. 259). Yilki, Victor Harbor, S. Aust., drift ( Womersley, 30.ix.1985; ADU, A56794). Nora Creina, S. Aust., drift (Womersley, 17.i.1971; ADU, A37829).

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

Distribution: From Cape du Couedic, Kangaroo I., and Christies Beach, S. Aust., to Coffs Harbour, N.S.W. Lord Howe I. (Allender & Kraft 1983, p. 91).

Kermadec Is (Lindauer et al. 1961, p. 196).

Taxonomic notes: Taonia australasica is probably more widespread than indicated by the above records.


AGARDH, J.G. (1894a). Analecta Algologica. Cont. I. Acta Univ. lund. 29, 1–144, Plates 1, 2.

ALLENDER, B.M. & KRAFT, G.T. (1983). The marine algae of Lord Howe Island (New South Wales): The Dictyotales and Cutleriales (Phaeophyta). Brunonia 6, 73–130.

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.

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 82B, 84 A–D.

Figure 82 image

Figure 82   enlarge

Fig. 82. A. Spatoglossum australasicum (ADU, A34905). B. Taonia austra/asica (ADU, A50866).

Figure 84 image

Figure 84   enlarge

Fig. 84. A–D. Taonia australasica (ADU, A50866). A. Upper part of thallus showing marginal apical cells, lines of hairs, and scattered sporangia. B. Longitudinal section showing apical cell and segmentation. C. Transverse section of thallus with an undivided sporangium. D. Longitudinal section of thallus with sporangia and phaeophycean hairs. E–H. Homoeostrichus canaliculatus (ADU, A18976). E. Upper branches. F. Surface view of cortical cell rows. G. Longitudinal section from apex to mature thallus showing segmentation. H. Transverse section with three rhizoids.

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