Electronic Flora of South Australia Species Fact Sheet

Dictyopteris acrostichoides (J. Agardh) Boergesen 1935: 36.

Phylum Phaeophyta – Order Dictyotales – Family Dictyotaceae – Tribe Zonarieae

Selected citations: Womersley 1967: 217.

Synonym

Haliseris acrostichoides J. Agardh 1882: 133.

Thallus (Fig. 78A) medium to dark brown, usually 10–40 cm long with one to a few fronds arising from a matted, rhizoidal holdfast 0.2–1.0 cm across and 0.2–2.0 cm long; epilithic. Growth from a group of several apical cells, margin behind the rounded apices entire. Fronds sparsely alternately branched above, with numerous proliferous branches arising from or near the midrib, of fairly uniform width but often increasing slightly towards the apices, (3–) 4–8 mm broad, with a central midrib but no lateral veins, with the wing becoming lacerate above and usually denuded below. Structure (Fig. 79A,B) of wing 2 cells thick at the margin, increasing to (4–) 5–6 cells thick in fertile parts, and the midrib 12–18 cells thick with smaller, more regular cells centrally; cortical cells (10–) 15–20 µm across in surface view, L/B I -2 (–3). Hair tufts scattered or tending near apices to occur in recurved lines, with hairs arising from small lateral derivatives of cortical cells, 15–20 µm in diameter.

Reproduction: Sporangia (Fig. 79C,D) scattered, usually densely, in elongate sori along the blades, leaving sterile zones over the midrib and a broad marginal zone; sporangia external to the cortex, with 1–2 laterally elongate stalk cells, subspherical to ovoid, 80–110 µm in diameter. Sexual reproduction unknown.

Lectotype from Tasmania (Gunn); in Herb. Agardh, LD, 48628.

Selected specimens: Warrnambool, Vic., drift (Womersley, 13.iv.1959; ADU, A22909). Queenscliff, Vic., drift (Clayton & Gordon-Mills, 4.xii.1983; ADU, A55432). Hyams Beach, Jervis Bay, N.S.W., upper sublittoral (Womersley, 16.i.1964; ADU, A27455).

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

Distribution: From Warrnambool, Vic. to Rockingham, Qld, and the north coast of Tasmania. The records from Bombay (Boergesen 1935, p. 36) and from Karachi (Nizamuddin & Saifullah 1967, p. 172) are doubtful, especially the latter.

Taxonomic notes: Dictyopteris acrostichoides is characterised by its proliferous branching from or near the midrib and sporangia arranged in longitudinal sori with a broad sterile margin. The distribution is unusual in that it covers the Victorian and northern Tasmanian coasts and the east coast of Australia to northern Queensland.

References:

AGARDH, J.G. (1882). Till algernes systematik. Acta Univ. lund. 17, 1–136, Plates 1–3.

BOERGESEN, F. (1935). A list of marine algae from Bombay. K. Dan. Vidensk. Selsk. Biol. Meddr 12, 1–64, Plates 1–10.

NIZAMUDDIN, M. & SAIFULLAH, S.M. (1967). Studies on marine algae of Karachi: Dictyopteris Lamouroux. Bot. Mar. 10, 169–179.

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 78A, 79 A–D.

Figure 78   enlarge

Fig. 78. A. Dictyopteris acrostichoides (ADU, A55432). B. Dictyopteris muelleri (ADU, A31658). C. Dictyopteris nigricans (ADU, A2296, holotype).

Figure 79   enlarge

Fig. 79. A–D. Dictyopteris acrostichoides (ADU, A55432). A. Transverse section of edge of wing. B. Transverse section of mid wing. C. Tetrasporangial thallus showing broad sterile zone between sporangia and margin. D. Transverse section with undivided tetrasporangia. E–J. Dictyopteris muelleri (ADU, A57063). E. Transverse section of edge of wing. F. Transverse section of part of midrib and lateral wing with rhizoids on both sides of midrib. G. Tetrasporangial thallus with midrib and hair tufts. H. Transverse section of thallus with tetrasporangia and a phaeophycean hair tuft. I. Male thallus with antheridial sori and hair tufts. J. Transverse section of thallus with antheridia. K,L. Dictyopteris nigricans (ADU, A4345). K. Transverse section of wing from edge to a phaeophycean hair tuft. L. Transverse section with an undivided sporangium.

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