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Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Dasyaceae
Selected citations: Silva et al. 1996: 444.
Synonyms
Dictyurus australasicus Sonder 1855: 527.
Dictyurus australis Sonder 1881: 31.
Thuretia teres Harvey 1862: pl. 191; 1863, synop.: xv. De Toni 1903: 1176; 1924: 436. De Toni & Forti 1923: 50. Falkenberg 1901: 674. Lucas 1912: 157. Lucas & Perrin 1947: 309. May 1965: 394. Womersley 1950: 183.
Dictyurus teres (Harvey) J. Agardh 1863: 1244.
Thallus (Fig. 233C) erect, tufted, with terete axes 3–7 cm high and 2–4 mm in diameter bearing alternate and more or less distichous laterals 3–10 mm long, with obtuse to truncate apices. Holdfast discoid, 1–4 mm across, usually with several axes; epilithic or epiphytic. Structure. Apices of axes and laterals sympodial, forming alternately distichous pseudolaterals which become semicircular with laterals developing to similar length and thus producing the terete network of monosiphonous filaments, with outer, free, short filaments (Fig. 234A, F) 200–500 µm long. Cells of network 20–50 µm in diameter and L/D 1–4, those of outer free filaments 40–60 µm in diameter and L/D (0.2–) 0.6–1. Pericentral cells 4, formed in alternating sequence, becoming corticated from close to the apex, the thick mature cortex (Fig. 234A) enveloping the basal cells of the pseudolaterals. Lateral axes arise from basal cells of pseudolaterals. Rhodoplasts discoid, becoming elongate or chained in larger cells.
Reproduction: Gametophytes dioecious. Procarps (Fig. 234B) occur on lower cells of the pseudolaterals, with 5 pericentral cells the fourth of which (occasionally also the fifth) is the supporting cell and cuts off the carpogonial branch and 2 groups of sterile cells. Post-fertilization the fusion cell (Fig. 234C) develops from the auxiliary cell, central cell of the fertile segment, sterile pericentral cells and lower gonimoblast cells, and the sterile groups divide. The much branched gonimoblast bears terminal clavate to ovoid carposporangia (Fig. 234E) 20–25 µm in diameter. Cystocarps (Fig. 234D) lie within the monosiphonous network, urceolate and 0.6–1.2 mm in diameter with a relatively long protruding neck, opening straight to flared; the pericarp arises pre-fertilization from the sterile pericentral cells and becomes 4–5 cells thick. Spermatangial branches (Figs 233D, 234F) ovoid, 60–100 µm in diameter, borne terminally on short monosiphonous stalks within the network, 3–6 cells long (Fig. 234G) with each cell forming 4–5 pericentral cells which cut off initials each of which produces 3–4 spermatangi a.
Tetrasporangial stichidia (Fig. 233E, 234H) develop from lower branched parts of the pseudolaterals, becoming 300–500 µm and 10–15 segments long, with each central cell cutting off 6–10 pericentral cells most of which form tetrasporangia (Fig. 2341) 25–50 µm in diameter and 3 pre-sporangial cover cells.
Type from Wilsons Prom., Victoria (Mueller, June 1853); holotype in MEL, 1006620.
Selected specimens: Hopetoun, W. Aust., on Hormosira, low eulittoral (Parsons, 20.xi.1968; AD, A33364). Eleven-mile Beach, Esperance, W. Aust., upper sublittoral (Parsons, 20.xi.1968; AD, A32598). Head of the Great Australian Bight, S. Aust., on Amphibolis antarctica (Womersley, 4.ii.1954; AD, A19153). Venus Bay, S. Aust., sublittoral fringe (Womersley, 17.i.1959; AD, A15174). Pennington Bay, Kangaroo I., S. Aust., sublittoral fringe (Womersley, 26.xii.1948; AD, A 10466). West Beach, Robe, S. Aust., 7–8 m deep (Baldock, 15.v.1967; AD, A34410). Blackfellows Caves, S. Aust., drift (Hotchkiss, 3.xi.1997; AD, A67347). Queenscliff, Vic., drift (Wollaston, 17.viii.1956; AD, A20560). Flinders, Vic., drift (Gordon-Mills, 9.xii.1983; AD, A55445). Walkerville, Vic., uppermost sublittoral (Sinkora A2665, 23.xi.1979; AD, A61063).
Distribution: Hopetoun, W. Aust., to Wilsons Prom., Victoria.
Taxonomic notes: Thuretia australasica occurs just below low tide level and deeper on rough-water coasts, both on larger algae or Amphibolis or directly on rock.
References:
AGARDH, J.G. (1863). Species Genera et Ordines Algarum. Vol. 2, Part 3, pp. 787–1291. (Gleerup: Lund.)
DE TONI, G.B. & FORTI, A. (1923). Alghe di Australia, Tasmania e Nouva Zelanda. Mein. R. Inst. Veneto Sci., Lett. Arti 29, 1–183, Plates 1–10.
DE TONI, G.B. (1903). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 3, pp. 775–1521 + 1523–1525. (Padua.)
DE TONI, G.B. (1924). Sylloge Algarum omnium hucusque Cognitarum. Vol. 6. Florideae. (Padua.)
FALKENBERG, P. (1901). Die Rhodomelaceen des Golfes von Neapel und der angrenzenden Meeres-abschnitte. Fauna und Flora des Golfes von Neapel. Monogr. 26. (Friedlander: Berlin.)
HARVEY, W.H. (1862). Phycologia Australica. Vol. 4, Plates 181–240. (Reeve: London.)
HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)
LUCAS, A.H.S. & PERRIN, F. (1947). The Seaweeds of South Australia. Part 2. The Red Seaweeds. (Govt Printer: Adelaide.)
LUCAS, A.H.S. (1912). Supplementary list of the marine algae of Australia. Proc. Linn. Soc. N.S.W. 37, 157–171.
MAY, V. (1965). A census and key to the species of Rhodophyceae (red algae) recorded from Australia. Contr. N.S.W. natn. Herb. 3, 349–429.
PARSONS, M.J. (1975). Morphology and taxonomy of the Dasyaceae and Lophothalieae (Rhodomelaceae) of the Rhodophyta. Aust. J. Bot. 23(4), 549–713.
SILVA, P.C., BASSON, P.W. & MOE, R.L. (1996). Catalogue of the Benthic Marine Algae of the Indian Ocean. (University of California Press: Berkeley, Los Angeles & London.)
SONDER, O.W. (1855). Algae annis 1852 et 1853 collectae. Linnaea 26, 506–528.
SONDER, O.W. (1881). In Mueller, F., Fragmenta Phytographiae Australiae. Supplementum ad volumen undecinum: Algae Australianae hactenus cognitae, pp. 1–42, 105–107. (Melbourne.)
WOMERSLEY, H.B.S. (1950). The marine algae of Kangaroo Island. III. List of Species 1. Trans. R. Soc. S. Aust. 73, 137–197.
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 233 C–E, 234.
Figure 233 enlarge
Fig. 233. A, B, Thuretia quercifolia (A, AD, A32229; B, AD, A20110). A. Ovoid spermatangial heads. B. Stichidia developed from intercalary linking cells of the network. C–E. Thuretia australasica (C, AD, A 10892; D, AD, A67347; E, AD, A 10466). C. Habit, on stem of Amphibolis. D. Ovoid spermatangial heads. E. Branched stichidia.
Figure 234 enlarge
Fig. 234. Thuretia australasica (A, B, D, H, I, AD, A10466; C, E–G, AD, A34410). A. Transverse section of main axis and part of network. B. Mature procarp. C. Fusion cell and young gonimoblast filaments. D. Mature cystocarp with neck protruding through the network. E. Mature carposporangia on gonimoblast filaments. F. Spermatangial heads on network filaments. G. Longitudinal section of spermatangial head. H. Mature stichidia on a pseudolateral. I. Longitudinal section of a stichidium. (All as in Parsons 1975, courtesy of Aust. J. Bot.)
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