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Sarcodia marginata J. Agardh 1892: 98.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Sarcodiaceae

Selected citations: De Toni 1900: 415. Kylin 1932: 56, p1. 20 fig. 49.

Thallus (Fig. 101A) medium to dark red, 7–17 cm high, complanately and subdichotomously branched at intervals of 1–3 (–5) cm, branches flat, 4–10 (–15) mm broad and 250–600 (–800) µm thick (margins slightly thicker), increasing in width upwards, with rounded axils and furcate, rounded and narrower apices. Holdfast crustose, 2–8 mm across, with one to several fronds; epilithic. Structure (Fig. 101B, D) of a medulla 80–250 µm broad of loosely entangled filaments 6–8 µm in diameter, produced from stellate inner cortical cells (Fig. 101B), and a cortex 4–7 cells and 120–250 (–300) µm thick, composed of large, inner, ovoid cells 30–70 (–100) µm in diameter, decreasing to a compact layer of outer cortical cells 5–10 µm in diameter, L/D 1.5–2. Rhodoplasts discoid, several per cell.

Reproduction: Sexual thalli probably dioecious. Carpogonial branches not clearly seen. Cystocarps (Fig. 101C) marginal, globular but broad-based, 1–2 mm in diameter, the carposporophyte with a basal reticulum of small cells, then erect, branched, gonimoblast filaments growing sideways or at right angles to the blade and bearing short chains of ovoid carposporangia each 15–25 µm in diameter. Pericarp (Fig. 101C) massive, 300–500 µm thick, ostiolate. Spermatangia not observed.

Type from Port Phillip, Vic. (Wilson); lectotype (to be selected) in Herb. Agardh, LD. A type label is affixed to LD 29871 (Fig. 49 in Kylin 1932) but this is from Puebla Bay (near Torquay), west of Port Phillip.

Selected specimens: Port Elliot, S. Aust., drift (Womersley, 17.x.1948; AD, A9362). Robe, S. Aust., drift (Womersley, 24.viii.1960; AD, A24453 and 24.xi.1990; AD, A60791). Cape Lannes, S. Aust., 1 m deep (Womersley, 20.xii.1971; AD, A41166 -"Marine Algae of southern Australia" No. 87). 1.3 km off Cape Northumberland, S. Aust., 15 m deep (Shepherd, 3.vii.1975; AD, A46370). Port MacDonnell, S. Aust., drift (Womersley, 21.iv.1984; AD, A55331). Mouth of Glenelg R., Vic., drift (Muir, Jan. 1950; AD, A15725).

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

Distribution: Port Elliot, S. Aust., to Port Phillip, Vic.

Taxonomic notes: S. marginata is apparently a deeper water (or in shaded pools) alga on rough-water coasts of SE South Australia and Victoria.


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

DE TONI, G.B. (1900). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 2, pp. 387–776. (Padua.)

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: 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 101 A–D, 103A.

Figure 101 image

Figure 101   enlarge

Fig. 101. A–D. Sarcodia marginata (A, AD, A41166; B, AD, A60791; C, D, AD, A46370). A. Habit. B. Transverse section of thallus with filamentous medulla (with outer stellate cells) and pseudoparenchymatous cortex. C. Section of cystocarp through ostiole. D. Transverse section of thallus with tetrasporangia. E. Trematocarpus concinnus (AD, A61617). Habit.

Figure 103 image

Figure 103   enlarge

Fig. 103. A. Sarcodia marginata (AD, A24453). Transverse section of cortex with tetrasporangia. B–D. Trematocarpus concinnus (AD, A61617). B. Cortical filaments with a 3-celled carpogonial branch. C. Cortical filaments with spermatangial chains. D. Cortical filaments with tetrasporangia. E. Trematocarpus affinis (AD, A31949). Cortical filaments with tetrasporangia. F–J. Dicranema revolutum (AD, A38408). F. Branch ends with cystocarps. G. Terminal branches with tetrasporangial nemathecia. H. Longitudinal section of branch apex. I. Transverse section of branch with medullary core and large inner cortical cells. J. Cortex with deep-seated carpogonial branches. [F–J after Kraft 1977b.]

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