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Electronic Flora of South Australia Genus Fact Sheet

Genus THURETIA Decaisne 1844: 236

Phylum Rhodophyta – Order Ceramiales – Family Dasyaceae

Thallus erect, terete or with flat and complanate branches. Axes sympodially developed, becoming polysiphonous are soon corticate, with rhodoplastic pseudolaterals forming a network surrounding the axes; holdfast discoid, rhizoidal. Structure. Axes with 4 pericentral cells produced in alternating sequence. Pseudolateral s arising from each segment of the axes, subdichotomous and linking by cell adhesion to form the network, with outer filaments unbranched.

Reproduction: Gametophytes dioecious. Procarps formed on basal cells of the pseudolaterals, with a 4-celled carpogonial branch and 2 groups of sterile cells, the supporting cell being the fourth pericentral cut off on the fertile segment; the sterile pericentral cells divide before fertilization to form the pericarp initials. Post-fertilization, fusion between the carpogonium and auxiliary cell occurs via a connecting cell, and the auxiliary cell, residual supporting cell, adjacent pericentral cells and lower gonimoblast cells contribute to the fusion cell. Carposporangia are terminal, with further ones developing laterally from below. Cystocarps have an urceolate pericarp, usually with a prominent neck. Spermatangial branchlets are subglobose and terminal on lateral monosiphonous branches within the pseudolateral network; 4–5 axial cells divide to form small initials and ultimately a surface layer of spermatangia.

Tetrasporangial stichidia develop from lower parts of the pseudolaterals, with each axial cell cutting off in alternating sequence usually 6 pericentral cells which divide to form 2–3 presporangial cover cells and the tetrasporangium.

Type species: T. quercifolia Decaisne 1844: 236.

Taxonomic notes: A genus of 3 species, the type and T. australasica from southern Australia and T. bornetii Vickers (1905, p. 63) from the West Indies (see Parsons 1975, p. 650).


DECAISNE, J. (1844). Note sur quelques algues à frondes réticulées. Ann. Sci. Nat., 3 Sér. Bot. 2, 233–236.

PARSONS, M.J. (1975). Morphology and taxonomy of the Dasyaceae and Lophothalieae (Rhodomelaceae) of the Rhodophyta. Aust. J. Bot. 23(4), 549–713.

VICKERS, A. (1905). Liste des algues marines de la Barbade. Ann. Sci. nat. bot. Ser. 9, 1, 45–66.

The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.

Author: M.J. Parsons and H.B.S. Womersley

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


1. Thallus network flat, 5–25 mm broad; stichidia ovoid, in transverse rows across the thallus forming sori at the branch tips; mature cystocarps covered by corticate filaments of the network

T. quercifolia

1. Thallus network terete or only slightly compressed, up to 4 mm broad; stichidia branched, fan-shaped, distichous on the main axis; mature cystocarps covered by ecorticate filaments of the network.

T. australasica

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