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Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Antithamnieae
Thallus (Fig. 52E) medium red-brown, erect, 3–8 cm high, with several sparsely branched axes, ecorticate or only lightly corticated near the base, each axial cell with (2–) 3 whorl-branchlets. Holdfast rhizoidal, 1–5 mm across; epilithic or on cockle shells. Structure. Apical cells 6–11 µm in diameter and L/D 0.8–1.2 (–2), enlarging shortly behind the apex and to 150–240 µm in diameter and L/D 1.5–3 in lower axial cells. Whorl-branchlets (Fig. 55A) 0.4–1 mm long, usually with 1–3 simple adaxial pinnules, basal cells 35–60 µm in diameter and L/D 0.8–1.2, L/D 2–3 above, tapering to subterminal cells 15–25 µm in diameter and L/D 1–1.5, terminal cells mucronate; upper cells often with short, lateral, curved spinous cells; gland cells borne on one or both cells of special, short, 2-celled branches on cells of whorl-branchlets, ovoid to subspherical, 16–25 (–50) µm in diameter. Corticating rhizoids arising from basal cells of whorl-branchlets, becoming entwined, (20–) 25–65 µm in diameter, cells L/D 4–7. Lateral branches arising from the basal cells of whorl-branchlets. Cells uninucleate in smaller cells; rhodoplasts discoid to elongate in small cells, ribbon like in larger cells.
Reproduction: Carpogonial branches borne on basal (= supporting) cells of whorl-branchlets, up to 12 at each branch apex. Post-fertilization successive rounded gonimolobes 150–350 µm across with ovoid to angular carposporangia 25–40 µm across are produced, partly protected by whorl-branchlets from below. Spermatangia unknown.
Tetrasporangia (Fig. 55A) occur on the special short branches which often bear the gland cells, ovoid, 45–55 µm in diameter, decussately divided.
Type from South Arm, Hobart, Tas., drift on cockles (Wollaston, 28.ii.1964); holotype in AD, A28033.
Selected specimens: Sorrento, Vic., 11 m deep (Womersley, 7.iv.1959; AD, A22771). Crawfish Rock, Westernport Bay. Vic., 6–9 m deep (Watson, 15.ix.1968; AD, A32824) and 4 m deep (Watson, 29.v.1974; AD, A44406, and 17.xi.1974; AD, A46233). Arch Rock, Ninepin Point, Tas., 10–14m deep (Kraft 9836a & Scott, 16.xii.1993: MELD and AD, A67797)
Distribution: Known from the type, and Sorrento and Crawfish Rock, Westernport Bay, Victoria, and SE Tasmania.
References:
WOLLASTON, E.M. (1968).Morphology and taxonomy of southern Australian genera of Crouanieae Schmitz (Ceramiaceae, Rhodophyta). Aust. J. Bot. 16, 217–417.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
Illustrations in Womersley Part IIIA, 1998: FIGS 52E, 55A.
Figure 52 enlarge
Fig. 52. A, B. Acrothamnion preissii (A, AD, A38236; B, AD, A58608). A. Branches with upcurved whorl-branchlets. B. Branch with whorl-branchlets bearing terminal gland cells and tetrasporangia. C. Macrothamnion pellucidum (AD, A63358). Habit. D. Macrothamnion secundum (AD, A20161). Habit. E. Macrothamnion pectenellum (AD, A46233). Habit. F. Macrothamnion acanthophorum (MELU and AD, A66643). Habit.
Figure 55 enlarge
Fig. 55. A. Macrothamnion pectenellum (AD, A28033). Branches with tetrasporangia and an axis apex. B–D. Macrothamnion acanthophorum (AD, A66643). B. Branch with opposite whorl-branchlets with gland cells on short branches. C, D. Branches with opposite whorl-branchlets bearing gland cells and tetrasporangia.
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