Electronic Flora of South Australia Species Fact Sheet

Erythroclonium sedoides (Harvey) Kylin 1932: 36.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Areschougiaceae

Selected citations: Min-Thein & Womersley 1976: 79, fig. 60A.


Areschougia (?) sedoides Harvey 1859a: pl. 117. J. Agardh 1872: 26; 1876: 283. Kylin 1932: 36.

Erythroclonium pyriferum J. Agardh 1872: 25; 1876: 279. Kylin 1932: 36.

Thallus (Fig. 115B) medium to dark red, 10–25 cm high, much branched above with elongate segments 2–4 mm long and 1–1.5 mm in diameter, branching from their apices; all except uppermost branches becoming heavily thickened (1–2 mm in diameter) and terete, and developing clusters at the nodes of short-stalked, adventitious, clavate segments 1–2 (–3) mm long and 0.7–1 mm in diameter. Holdfast discoid, with a single stipe soon becoming branched; epilithic. Structure uniaxial with the axial filament conspicuous throughout, with each axial cell bearing two periaxial filaments at right angles, alternating on adjacent cells, with rhizoids twisted around the axial filament in young segments; medulla with lax periaxial filaments above, becoming filled with rhizoids in thickened branches (Fig. 115C). Cortex pseudoparenchymatous, 2–3 cells thick in upper segments, 3–6 cells thick in adventitious segments, inner cells ovoid and (10–) 15–20 µm in diameter, outer cells 8–16 µm in diameter, L/D 1–2; outer cortical cells in lower branches cutting off files of elongate cells L/D (1–) 2–3,10–20 cells long.

Reproduction: Early sexual reproduction unknown. Cystocarps (Harvey 1859a, pl. 117) within the medulla of adventitious segments, with chains of ovoid carposporangia.

Tetrasporangia (Fig. 115D) scattered in the cortex of adventitious segments, developed from a mid cortical cell and without outer cortical cells, lying in the cortex and pit-connected basally, ovoid, 40–50 µm long and 20–32 µm in diameter, zonately divided.

Type from Fremantle, W. Aust. (Clifton); holotype in Herb. Harvey, TCD; probable isotype in MEL, 44736.

Selected specimens: Dongara, W. Aust., drift (Baird, Feb. 1944; UWA, A1339). Point Peron, W. Aust., drift (Smith, 6.vi.1947; UWA, 178 and AD, A5686) and (Summerhayes, 4.vi.1947; AD, A11926). Geographe Bay, W. Aust., drift (Feb. 1880; MEL, 44739). Augusta; W. Aust., drift (Smith, Aug. 1966; UWA, A1338).

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

Distribution: Dongara to Augusta, W. Aust.

Taxonomic notes: Erythroclonium sedoides is distinctive in habit and most specimens lack the upper much branched segmented parts. It is probably a deep water species, just extending to southern Australia, and the reproductive details still await investigation.

Although details of the sexual reproduction are unknown, it agrees well in vegetative, structural and tetrasporangial features with Erythroclonium.


AGARDH, J.G. (1872). Bidrag till Florideernes Systematik. Acta Univ. hind. 8, 1–60.

AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 - Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)

HARVEY, W.H. (1859a). Phycologia Australica. Vol. 2, Plates 61–120. (Reeve: London.)

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

MIN-THEIN, U. & WOMERSLEY, H.B.S. (1976). Studies on southern Australian taxa of Solieriaceae, Rhabdoniaceae and Rhodophyllidaceae (Rhodophyta). Aust. J. Bot. 24, 1–166.

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

Author: 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.

Illustration in Womersley Part IIIA, 1994: FIG. 115 B–D.

Figure 115 image

Figure 115   enlarge

Fig. 115. A. Erythroclonium muelleri (AD, A46348). Habit. B–D. Erythroclonium sedoides [B, C, UWA, A1339 (AD, A44584); D, AD, A11926]. B. Habit. C. Transverse section of older branch. D. Section of cortex with tetrasporangia. E. Erythroclonium angustatum (AD, A43965). Habit. F, G. Erythroclonium sonderi (F, AD, A33101; G, AD, A52489). F. Habit. G. Section of cystocarp. [B as in Min-Thein & Womersley 1976.]

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