Electronic Flora of South Australia Species Fact Sheet

Desmarestia ligulata (Lightfoot) Lamouroux 1813: 45.

Phylum Phaeophyta – Order Desmarestiales – Family Desmarestiaceae

Selected citations: Anderson 1985: 437, fig. 31. Harvey 1847: pl. 115. Womersley 1967: 242.

Thallus (Fig. 94B) medium brown to greenish brown, usually 20–50 cm long, complanately branched, with one to a few fronds arising from a small discoid holdfast 2–5 mm across; epilithic. Growth trichothallic, with a single, uniseriate, apical filament (Fig. 96B), 30–40 µm in diameter with cells L/B 2–4 above, to each branch, bearing opposite uniseriate branches above (later lost) and below the meristem becoming corticated by rhizoidal development and later periclinal divisions. Fronds (Fig. 96A) with frequent opposite branching to 3 orders, with the axis and primary laterals mostly 2–5 mm broad, more or less linear but tapering apically and basally, dentate, and with a faint to conspicuous midrib (the axial filament); slender secondary or tertiary laterals occur as short (2–5 mm long) feathery tufts when young, often remaining as marginal dentations. Structure (Fig. 96E) of a relatively conspicuous, thick walled, central axial filament, surrounded by a medulla of large cells intermixed with slender hyphae (more prominent around the axial filament), decreasing to the small-celled cortex of angular cells, 5–10 (–12) µm across in surface view.

Reproduction: Reproduction by scattered, single, sporangia (Fig. 96C,D) formed from slightly transformed cortical cells, each producing a few motile meiospores. Gametophytes little known, probably monoecious, oogamous.

Type from Scotland; lost? (Chapman 1972, p. 17).

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

Distribution: Widespread in the cold temperate Northern and Southern Hemispheres.

In southern Australia, known from Nora Creina, S. Aust., to Western Port, Vic., and around Tasmania, but apparently rare.

Taxonomic notes: Known Australian specimens: Nora Creina, S. Aust., drift (Gordon, 26.i.1967; ADU, A31634). Port MacDonnell, S. Aust., drift (Womersley, 15.iv.1959; ADU, A22255). Bridgewater Bay, Vic., drift (Womersley, 25.i.1967; ADU, A31767). Western Port, Vic. (Harvey, Alg. Aust. Exsicc. 47H; ADU, A18370). Phillip I., Vic. (Harvey, Trav. Set. 406; MEL, 15901/2). Fluted Cape, Bruny I., Tas., 16 m deep (Shepherd, 12.ii.1972; ADU, A41993). Iron Pot, D'Entrecasteaux Ch., Tas. (Sanderson, 1.vi.1984; HO, 79665).

D. chordalis Hooker & Harvey was recorded from Burnie, Tas., by De Toni & Forti (1923, p. 80), but this record is almost certainly incorrect.

The few specimens from southern Australia agree well in habit, dimensions and sporangia (group 1 of Moe & Silva 1977b, p. 160) with D. ligulata from Britain and elsewhere, as recorded by Anderson (1985).

References:

ANDERSON, R.J. (1985). Morphological and taxonomic relationships among branched, ligulate members of the genus Desmarestia (Phaeophyceae, Desmarestiales), with particular reference to South African D. firma. Can. J. Bot. 63, 437–447.

CHAPMAN, A.R.O. (1972). Morphological variation and its taxonomic implications in the ligulate members of the genus Desmarestia occurring on the west coast of North America. Syesis 5, 1–20.

DE TONI, G.B. & FORTI, A. (1923). Alghe di Australia, Tasmania e Nouva Zelanda. Memorie R. Inst. veneto Sci. 29, 1–183.

HARVEY, W.H. (1847). Phycologia Britannica. Plates 73–144. (Reeve: London.)

LAMOUROUX, J.V.F. (1813). Essai sur les genres de la famille des thalassiophytes non articulées. Ann. Mus. Hist. Nat., Paris 20, 21–47, 115–139, 267–293, Plates 7–13(1–7).

MOE, R.L. & SILVA, P.C. (1977b). Sporangia in the brown algal genus Desmarestia with special reference to Antarctic D. ligulata. Bull. Jap. Soc. Phycol. 25, 159–167.

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 94B, 96 A–E.

Figure 94   enlarge

Fig. 94. A. Cutleria multifida (ADU, A57020). B. Desmarestia ligulata (ADU, A22255). C. Arthrocladia villosa (ADU, A52837).

Figure 96   enlarge

Fig. 96. A–E. Desmarestia ligulata (A,C–E, ADU, A22255; B, Harvey, Alg. Aust. Exsicc. 47, ADU, A18370). A. Upper branch with laterals, midrib and opposite lateral veins. B. Apex of branch with trichothallic filament and opposite branches, with cortication below the meristematic zone. C. Surface view of cortical cells (some with phaeoplasts) and unilocular sporangia. D. Transverse section of cortex with unilocular sporangia. E. Transverse section of older thallus with central axial filament (on right) and the wing region (on left). F–H. Arthrocladia villosa (ADU, A52837). F. Older branch with more or less whorled (up to four) fascicles of filaments. G. Apex of branch with trichothallic filament bearing 2-4 opposite or whorled laterals, with corticating filaments below the meristematic zone. H. Lateral filaments with chains of unilocular sporangia.

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