Electronic Flora of South Australia Species Fact Sheet

Zonaria crenata J. Agardh 1872: 48; 1894a: 13.

Phylum Phaeophyta – Order Dictyotales – Family Dictyotaceae – Tribe Zonarieae

Selected citations: Womersley 1967: 226.

Thallus (Fig. 88B) light to medium brown, occasionally dark brown, (5–) 10–25 (–35) cm long, much branched, branches complanate but often displaced, denuded below with stupose axes 1–3 (–5) mm thick and a matted rhizoidal holdfast 5–20 (–25) mm across and 5–15 mm long; epilithic. Fronds (Fig. 89G) irregularly branched from apical splitting, margin below the apices usually irregularly spinous, upper parts (2–) 4–10 (–12) mm broad, narrowing to 2–4 mm broad near the stupose central axis where the lateral wing has disintegrated; upper fronds covered with a network (Fig. 89G) of the hydroid Scoresbia daidala Watson. Structure (Fig. 89H,I) 6 cells and 80–120 (–150) µm thick throughout, with cells in regular rows in transverse section; cortical cells the same size as medullary cells (or becoming paired), 2–4 to each medullary cell lengthwise, 20–27 µm across (when not paired) in surface view, L/B (0.6–) 1–1.5 (–2). Hair tufts apparently absent.

Reproduction: Sori of sporangia (Fig. 89G) scattered on upper branches, irregularly ovate, 0.5–2 mm long and 0.3–1 mm across, with paraphyses 5–9 cells and 150–250 µm long, with the terminal cell subspherical, 35–45 ,um in diameter; sporangia (Fig. 89I) clavate to ovoid, 120–160 µm long and 60–85 µm in diameter, with 8 spores, without a stalk cell. Sexual reproduction unknown.

Type from Fremantle, W. Aust.; lectotype in Herb. Agardh, LD, 48069.

Selected specimens: Cosy Corner, Torbay Head, W. Aust., drift (Mitchell, 28.ix.1966; ADU, A30789). Ward I., S. Aust., 18–23 m deep (Shepherd, 3.iii.1980; ADU, A50900). Investigator Strait, S. Aust., 33 m deep, 35°29'S, 137°17'E (Watson, 20.i.1971; ADU, A38547). Marion Light, Gulf St Vincent, S. Aust., 24 m deep, 3 km S.E. (Shepherd, 5.ii.1969; ADU, A33888). 20 km W.S.W of Outer Harbour, S. Aust., 22–25 m deep (McFarlane, I 1.ix.1975; ADU, A46629). Port Noarlunga, S. Aust., 24 m deep 5 km offshore (Ottaway, 3.ii.1981; ADU, A52098). Aldinga, S. Aust., drift (Womersley, 17.ix.1966; ADU, A30714). Stanley Beach, S. coast Kangaroo I., S. Aust., drift ( Womersley, 6.ii.1957; ADU, A20912). Kingston, S. Aust., drift (Womersley, 16.xii.1986; ADU, A57343-"Marine Algae of southern Australia No. 287. Eastern Bass Str., 24 m deep (Gippsland Scallop Survey, 3.ii.1971; ADU, A39503). Byron Bay, N.S.W., 13 m deep (Clarke & Silvester, 18.viii.1973; ADU, A43978). Southport, Old, drift (Cribb 43, March 1948; ADU, A8941).

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

Distribution: From Fremantle, W. Aust. to Southport, Qld.

Taxonomic notes: Z. crenata was recorded from Chile by Etcheverry (1960, p.101) but his figures clearly apply to a different species.

Z. crenata is characterised by the moderately slender thallus 6 cells thick, by the relatively broad branch ends, and especially by the network of hydroid that is consistently present over the upper branches; only very few specimens are Z. crenata-like but with no hydroid.


AGARDH, J.G. (1872). Till algernes systematik. Ada Univ. lund. 9(8), 1–71.

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

ETCHEVERRY, H. (1960). Algas marinas de las Islas Oceanicas Chilenas. Revta Biol. mar. 10, 83–132, Plates 1–6.

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 88B, 89 G–I.

Figure 88 image

Figure 88   enlarge

Fig. 88. A. Zonaria angustata (ADU, A55364). B. Zonaria crenata (ADU, A46629).

Figure 89 image

Figure 89   enlarge

Fig. 89. A–F. Zonaria angustata (ADU, A29660). A. Branches with sporangial sori with indusia. and hair tufts. B. Transverse section of thallus with sporangia. C. Branch with oogonial sori and hair tufts. D. Transverse section of thallus with oogonia. E. Branch with antheridial sori. F. Transverse section of thallus with antheridia. G–I. Zonaria crenata (ADU, A30714). G. Surface view of thallus with hydroid network and sporangial sori. H. Longitudinal section of apex showing segmentation. 1. Transverse section of thallus with sporangia and paraphyses.

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