Electronic Flora of South Australia Species Fact Sheet
Phylum Phaeophyta – Order Dictyotales – Family Dictyotaceae – Tribe Zonarieae
Selected citations: Womersley 1967: 227.
Zonaria interrupta sensu Harvey 1862: pl. 190.
Thallus (Fig. 90B) dark brown, (5–) 10–20 (–25) cm long, broadly flabellate when young, becoming much branched and essentially complanate, with axes and lower branches stupose and 2–5 (–8) mm broad, arising from a matted rhizoidal holdfast (2–) 5–15 mm across and 2–10 mm long; epilithic. Fronds complanate, irregularly laterally branched, branches more or less linear or with occasional short spinous laterals, 2–5 (–10) mm broad in mid and upper parts with no or slight growth zones and sometimes with a slight, darker, midrib, broader in juvenile plants near their base. Structure (Fig. 91E) 8–10 cells and 120–160 (–180) µm thick, with cells in regular rows in transverse section and the cortical cells nearly all paired (Fig. 91D), (2–) 4–6 (–7) to each medullary cell lengthwise (with the subcortical layer sometimes once subdivided), 8–14 µm across (when paired) and L/B (0.7–) 1–1.5 (–2.5). Hair tufts inconspicuous, slight.
Reproduction: Sori of sporangia (Fig. 91E) amongst paraphyses on upper and mid branches; sporangia clavate to pyriform, 90–180 µm long and 70–115 µm in diameter, with 8 spores, without a stalk cell; paraphyses 7–10 cells and 250–400 µm long, clavate with elongate-ovoid end cells 30–40 µm in diameter. Sexual reproduction unknown in Australian plants (see Lindauer et al. 1961, p. 198, under Z. angustata).
Type from Warrington, Otago, New Zealand; lectotype in Herb. Agardh, LD, 48129.
Selected specimens: Point Moore, Geraldton, W Aust., drift ( Womersley, 17.ix.1979; ADU, A51176). Cowaramup Bay, W. Aust., 2–3 m deep (Clarke & Engler, 1.ix.1979; ADU, A50661). Israelite Bay, W. Aust., drift ( Wells, 10.xii.1974; ADU, A46083). Egg I., Isles of St Francis, S. Aust., 32–38 m deep (Shepherd, 11.i.1971; ADU, A38106). Tiparra reef, Spencer Gulf, S. Aust., 11 m deep (Shepherd, 31.x.1970; ADU, A37643). Middle R., Kangaroo I., S. Aust., drift (Womersley, 8.i.1946; ADU, A3382). Nora Creina, S. Aust., reef pools (Womersley, 26.i.1967; ADU, A31640). Port Phillip Heads, Vic., 22 m deep (Watson, 29.iii.1985; ADU, A57043). Stapleton Point, Prosser Bay, Tas., 6–8 m deep (Shepherd, 10.ii.1970; ADU, A35750). Ninepin Point, D'Entrecasteaux Ch., Tas., 5 m deep (Brown & Ferris, 1.xi.1982; ADU, A56471).
Distribution: New Zealand.
In southern Australia, from Geraldton, W. Aust., to Port Phillip Heads, Vic., and around Tasmania.
Taxonomic notes: Z. turneriana appears to be typically a deep water (to 30 m) species, and deeper specimens have broader branches. It is best developed on south-east Australian coasts and in Western Australia and is not so prominent on the central coasts. Many Australian specimens match New Zealand ones well, having robust, complanate thalli usually 8 or 10 cells thick, more or less linear, with sporangia plus paraphyses in scattered sori. However, New Zealand specimens can be 12 cells thick and the paraphyses have subspherical end cells rather than elongate-ovoid ones. Z. turneriana can only be determined on the basis of mature, fertile plants, and young sterile plants, or basal parts, cannot be separated from Z. angustata or Z. spiralis. Further studies are needed on the variation in this complex of species.
AGARDH, J.G. (1871). Om Chatham-Oarnes Alger. K. Vetensk Akad. Forschandl. 5, 435–456.
AGARDH, J.G. (1894a). Analecta Algologica. Cont. I. Acta Univ. lund. 29, 1–144, Plates 1, 2.
HARVEY, W.H. (1862). Phycologia Australica. Vol. 4, Plates 181–240. (Reeve: London.)
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.
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 90B, 91D,E.
Figure 90 enlarge
Fig. 90. A. Zonaria spiralis (ADU, A27254). B. Zonaria turneriana (ADU, A57043).
Figure 91 enlarge
Fig. 91. A–C. Zonaria spiralis (ADU, A57082). A. Spiral branches with sporangial sori. B. Surface view of thallus with mostly paired cortical cells. C. Transverse section of thallus with sporangia and paraphyses. D,E. Zonaria turneriana (ADU, A57043). D. Surface view of thallus with paired cortical cells. E. Transverse section of thallus with sporangia and paraphyses. F,G. Lobophora variegata (ADU, A57111). F. Apical cell and segmentation of thallus, with phaeophycean hairs. G. Transverse section of thallus with sporangia.
State Herbarium of South Australia