Electronic Flora of South Australia Species Fact Sheet

Sargassum decipiens (R. Brown ex Turner) J. Agardh 1872: 63; 1889: 51(?).

Phylum Phaeophyta – Order Fucales – Family Sargassaceae

Selected citations: Womersley 1954b: 348, fig. 1e,f, pl. 4 fig. 1.

Synonyms

Fucus decipiens R. Brown ex Turner 1811: 78, pl. 166a,c,d (not b).

Sargassum muriculatum J. Agardh 1872: 58; 1889: 44, pl. 14 fig. II.

Thallus (Fig. 158A) medium brown, 10–50 cm long, with simple or branched stipes 2–15 cm long, compressed, 3–6 mm broad, with prominent, distichous, branch residues, bearing apically and distichously (2–) 4–8 primary branches, the apical ones immature. Holdfast discoid-conical, (3–) 5–18 mm across, with one (–3) stipes; epilithic. Primary branches 2–40 cm long, radially branched with densely clustered laterals below (especially when sterile); lower primary branches becoming denuded of laterals except for muricate residues. Laterals (lower) simple or once or twice divided, compressed to sub-terete, 1–4 cm long and 0.5–2 mm broad, often with prominent cryptostomata; upper (fertile) laterals 1–3 cm long, much branched with filiform, terete, ramuli. Vesicles developing in late winter on fertile ramuli, petiolate, sub-spherical to ovoid, 1–2 (–3) mm in diameter, with a short to long mucro.

Reproduction: Thalli monoecious. Receptacles (Fig. 160C) bisexual, forming racemose clusters on upper ramuli, simple or occasionally branched, petiolate, elongate-ovoid to lanceolate, smooth to verrucose, 1–4 (–7) mm long and 300–800 (–1200) µm in diameter, with scattered ostioles. Conceptacles unisexual or occasionally bisexual; oogonia sessile, subspherical to ovoid, few per conceptacle, 240–350 µm long and 160–320 µm in diameter; antheridia sessile or on branched paraphyses, ovoid, 16–24 µm long and 7–10 µ in diameter.

Type from Port Dalrymple (Tamar Est. mouth), Tas.; in BM.

Selected specimens: Cape Naturaliste, W. Aust., uppermost sublittoral (Womersley, Clarke & Engler, 2.ix.1979; ADU, A50626). Eucla, W. Aust., drift (Womersley, 2.ii.1954; ADU, A19338). St Francis I., Isles of St Francis, S. Aust., 13 m deep (Shepherd, 8.i.1971; ADU, A37916). Tiparra reef, S. Aust., 5 m deep (Shepherd, 18.x.1972; ADU, A42786). Pondalowie Bay, Yorke Pen., S. Aust., 5–8 m deep (Shepherd, 14.iv.1963; ADU, A26610). Port Willunga, S. Aust., upper sublittoral pools (Shepley, 29.ix.1954; ADU, A20254). Pennington Bay, Kangaroo I., S. Aust., on main reef (Womersley, 1.xi.1947; ADU, A6097). Rocky Point beach, Kangaroo I., S. Aust., drift (Womersley, 21.viii.1948; ADU, A8625). Robe, S. Aust., reef pools (Womersley, 18.viii.1957; ADU, A21174). St Leonards, Port Phillip, Vic., 1–3 m deep (Womersley, 9.viii.1959; ADU, A23094). Crawfish Rock, Westernport Bay, Vic., 3–5 m deep (Watson, 25.iv.1969; ADU, A34288). Stewarts Bay, Port Arthur, Tas. (Cribb 116.12, 23.i.1951; ADU, A16196). Boat Harbour Beach, N. Tas., lower eulittoral pools (Womersley, 3.x.1986; ADU, A57476-"Marine Algae of southern Australia" No. 290).


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

Distribution: From Cape Naturaliste, W. Aust., to Westernport Bay, Vic., and around Tasmania.

Taxonomic notes: Sargassum decipiens is not a typical member of subgenus Phyllotrichia since the lower laterals are narrow (under 2 mm broad) and only occasionally with 1–2 branches, and during the sterile season (mid summer to mid winter) the plants consist of basal stipes with several short primary branches densely covered with short laterals. However, the form, distichous branching to the stipe and receptacles ally it to S. sonderi and it is best placed in Phyllotrichia. The long stipes of old plants with their branch residues indicate ages of 10–15 years.

J. Agardh's figures (1889, pl. 15 figs 8–12) of S. decipiens are probably not of this species but more likely S. sonderi.

References:

AGARDH, J.G. (1872). Till algernes systematik. Ada Univ. lund. 9(8), 1–71.

AGARDH, J.G. (1889). Species Sargassorum Australiae. K. Svenska Vetenskapsakad. Handl. 23(3), 1–133, Plates 1–31.

TURNER, D. (1811). Fuci sive Plantarum Fucorum Generi a Botanicis Ascriptarum 'cones Descriptiones et Historia. Vol. 3, pp. 1–148, Plates 135–196. (London.)

WOMERSLEY, H.B.S. (1954b). Australian species of Sargassum, subgenus Phyllotrichia. Aust. J. Bot. 2, 337–354, Plates 1–5.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia


Illustrations in Womersley Part II, 1997: FIGS 158A, 160C.

Figure 158 image

Figure 158   enlarge

Fig. 158. A. Sargassum decipiens (ADU, A42786). B. Sargassum sonderi (ADU, A38632).

Figure 160 image

Figure 160   enlarge

Fig. 160. Receptacles of species of Sargassum subgenus Phyllotrichia. A. Sargassum decurrens (ADU. A53922). B. Sargassum heteromorphum (ADU, A23954). C. Sargassum decipiens (ADU, A57476). D. Sargassum sonderi (ADU, A9314). E. Sargassum varians (ADU, A55724). F. Sargassum verruculosum (ADU. A18826).


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