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Peltasta australis J. Agardh 1892: 102.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Dicranemataceae

Selected citations: Kraft 1977b: 235, figs 6, 7, 15, 16. Kylin 1932: 69, pl. 28 fig. 70.


Curdiea gymnogongroides J. Agardh 1901: 104. Kylin 1932: 61, pl. 26 fig. 63.

Thallus (Figs 105E, 106A) dark brown-red, erect, 5–13 cm high, cartilaginous, forming clumps of subdichotomous fronds more or less complanately branched at intervals of (2–) 4–10 (–15) mm, branches compressed, (1–) 2–3 mm broad, 250–350 µm thick. Holdfast (Fig. 106A) stoloniferous, branched, with small haptera; epilithic. Structure multiaxial, with a central medullary layer (Figs 105F, 106C) 1–3 cells broad, cells elongate and with yellow refractive contents, and a broad pseudoparenchymatous cortex of inner ovoid cells 20–30 µm in diameter and small-celled outer cortex, outer cells 4–5 µm in diameter, L/D 2–3. Rhodoplasts discoid, several per cell.

Reproduction: Sexual thalli monoecious; non procarpic. Carpogonial branches (Fig. 106D) 3-celled, straight, borne on mid cortical cells near branch apices. Auxiliary cells apparently adjacent to carpogonia, fusion cell (Fig. 106E) with numerous radiating arms of gonimoblast filaments which, with fused vegetative cells, forms a subspherical placenta (Fig. 105G) with the peripheral gonimoblast layer forming clumps of dividing cells which develop chains of 2 (–3) carposporangia 4–5 µm in diameter. Pericarp thick, ostiolate, with the cystocarp (Fig. 106B) forming a subspherical lateral knob at the branch tip. Spermatangia (Fig. 106C, F) in small, sunken clusters developed from isolated cortical cells on both sides of the branches, ovoid, 1.5–2.5 µm in diameter.

Tetrasporangia (Fig. 106G) scattered amongst cortical cells on both surfaces, near branch apices, basally attached, ovoid, 14–24 µm long and 7–12 µm in diameter, zonately divided.

Type from Port Phillip, Vic. (Wilson 21/91; 20.i.1891); holotype in Herb. Agardh, LD, 32555.

Selected specimens: Dubious Rock, West I., S. Aust., 13 m deep (Shepherd, 3.i.1966; AD, A30343). Margaret Brock Reef, Cape Jaffa, S. Aust., 4–5 m deep in caves (R. Lewis, 29.xi.1972; AD, A42921). Nora Creina, S. Aust., 5–6 m deep (Kraft & R. Lewis, 13.v.1972; AD, A44740) and 4–5 m deep (Kraft, 29.xii.1976; MELU, A23539). 9 km off Cape Northumberland, S. Aust., 38 m deep (Shepherd, 12.iii.1975; AD, A46186). Warrnambool, Vic., drift (Kraft & Herrington, 28.x.1988; MELU, A39561/62). Marengo (Apollo Bay), Vic., 6–7 m deep (Kraft & O'Brien, 18.iv.1975; MELU, A39559). Port Phillip Heads, Vic. (Wilson, 16.i.1895; AD, A8277). Cape Woolamai, Vic., 15–18 m deep (Goldsworthy & Berthold, 16.ii.1990; AD, A60192). Marion Bay, Tas., 10 m deep (Shepherd, 13.ii.1970; AD, A35668). Ninepin Point, D'Entrecasteaux Ch., Tas., 5 m deep (Brown, Ferris & Womersley, 1.xi.1982; AD, A56480).

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

Distribution: West I., S. Aust., to Cape Woolamai, Vic., and SE Tasmania.

Taxonomic notes: Peltasta australis is readily recognised by its habit and the medullary core of elongate cells with yellow refractive contents. It is usually a deep water alga (10–38 m deep) occurring in shaded areas in shallower water.


AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.

AGARDH, J.G. (1901). Species Genera et Ordines Algarum. Vol. 3, Part 4, pp. 1–149. (Gleerup: Lund.)

KRAFT, G.T. (1977b). Studies of marine algae in the lesser-known families of the Gigartinales (Rhodophyta). H. The Dicranemaceae. Aust. J. Bot. 25, 219–267.

KYLIN, H. (1932). Die Florideenordnung Gigartinales. Lunds Univ. Årsskr. N.F. Avd. 2, 28 (8), 1–88, Plates 1–28.

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

Author: G. T. Kraft & H.B.S. Womersley

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustrations in Womersley Part IIIA, 1994: FIGS 105 E–G, 106 A–G.

Figure 105 image

Figure 105   enlarge

Fig. 105. A, B. Dicranema revolutum (A, AD, A44665; B, AD, A38408). A. Habit. B. Section of carposporophyte with fusion cell (arrow). C, D. Dicranema cincinnalis (C, AD, A44737, holotype; D, AD, A44739). C. Habit, on Amphibolis stem. D. Transverse section of branch with a carposporophyte. E–G. Peltasta australis (E, AD, A46186; F, G, AD, A30343). E. Habit. F. Transverse section of thallus. G. Section of a mature cystocarp. [B–D, as in Kraft 1977b.]

Figure 106 image

Figure 106   enlarge

Fig. 106. A–G. Peltasta australis (A, B, MELU, A23539; C–F, AD, A44740; G, AD, A8277). A. Prostrate stolons with erect axes and attaching haptera. B. Cystocarps on damaged branches. C. Longitudinal section with medullary core of refractive cells and sunken spermatangial clusters in cortex. D. Section of cortex with carpogonial branches. E. Young fusion cell with gonimoblast filaments. F. Section of cortex with sunken spermatangial clusters. G. Section of cortex with tetrasporangia. H–N. Tylotus obtusatus (H–M, AD, A42228; N, AD, A41823). H. Habit of cystocarpic thallus from underside, showing basal attaching haptera and distal cystocarps. I. Longitudinal section of thallus apex. J. Section of cortex with a carpogonial branch and an auxiliary cell fused to a carpogonium. K. Fusion cell with young gonimoblast filaments. L. A carposporangial lobe from a mature carposporophyte. M. Section of cortex with sunken spermatangial clusters. N. Section of a tetrasporangial nemathecium. [A–M after Kraft 1977b.]

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