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Electronic Flora of South Australia Species Fact Sheet

Plocamium preissianum Sonder 1845: 54; 1846: 192; 1853: 682.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Plocamiaceae

Selected citations: J. Agardh 1852: 399; 1876: 342. De Toni 1900: 594. De Toni & Forti 1923: 32. Harvey 1855a: 553; 1859a: p1. 63; 1863, synop.: xxxix. Kützing 1849: 885; 1866: 19, pl. 53d-f (fig. as P. preissii). Levring 1946: 222. Lucas 1909: 34; 1929b: 50. Lucas & Perrin 1947: 211, fig. 75. May 1965: 372. Reinbold 1898: 46. Womersley 1950: 170; 1966: 147; 1971a: 20, figs 29–35.

Thallus (Fig. 130A) robust, 20–50 cm high. Erect axes (1–) 1.5–2 (–3) mm broad, usually long and irregularly branched, becoming thickened and sometimes appearing costate in older parts. Ramuli in alternating series of 3 (–4), occasionally with some in pairs in certain plants, the uppermost ramulus (occasionally the upper two) usually developing into a lateral branch; lower ramuli subulate to linear, (1.5–) 2–3 (–4) mm long and (200–) 300–400 (–500) µm broad at their base, usually strongly serrate abaxially (rarely entire).

Reproduction: Sexual thalli dioecious. Cystocarps single or occasionally adjacent, sessile on the axis or on either margin of the ramuli or sessile in comparable positions on small axillary branchlets, 0.7–1 (–1.5) mm across, globular and becoming strongly verrucose (Fig. 130B). Spermatangia covering extensive areas on both surfaces of young apices and ramuli (Fig. 130C, D).

Stichidia in dense axillary clusters (Fig. 130E) and frequently extending along the margins of the adjacent axis and ramuli; individual stichidia (Fig. 130F) simple or basally branched only, linear-arcuate, (100–) 200–500 µm long (sometimes continuing growth to 1.5 mm long) and (25–) 50–75 (–100) µm in diameter. Tetrasporangia in 1–2 series, ovoid, 53–66 µm long and 40–53 µm in diameter, zonately divided.

Type from "austro-occidentale Novae Hollandiae" (Preiss); holotype in MEL, 1005964.

Selected specimens: Pelsart I., Abrolhos Is, W. Aust., drift (Womersley, 1.ix.1947; AD, A5871). Geraldton, W. Aust. (Carter, Sept. 1926; NSW). Whitford Beach, Perth, W. Aust., 6 m deep (Cook, 20.viii.1979; AD, A50578). Cannan Reefs (S of Isles of St Francis), S. Aust., 20–25 m deep (Branden, 25.i.1991; AD, A61091). Pearson I., S. Aust., 30–32 m deep (Shepherd, 7.i.1969; AD, A33685). Snapper Point, Aldinga, S. Aust., 6 m deep (URGSA, 23.xi.1958; AD, A22016). Pennington Bay, Kangaroo I., S. Aust., drift (Womersley, 17.i.1944; AD, A2516). Young Rocks, S of Kangaroo I., S. Aust., 16–30 m deep (Branden, 18.vi.1991; AD, A61460). Amphitheatre Rock, West I., S. Aust., 13–22 m deep (Shepherd, 1.i.1969; AD, A33242). West I., S. Aust., 10 m deep (Shepherd, 13.vi.1970;

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

Distribution: From the Abrolhos Islands and Geraldton, W. Aust., to Wilsons Promontory, Vic. Common on coasts subject to strong wave action and known from depths of 2 to 50 m.

Taxonomic notes: AD, A35912). 1.35 km off Middle Point, Cape Northumberland, S. Aust., 15 m deep (Johnson, 13.vii.1974; AD, A45458). Lady Julia Percy I., Vic., 19 m deep (Shepherd, 4.i.1968; AD, A32425). Portsea, Vic., 20 m deep off ocean beach (Macpherson, 15.v.1963; AD, A28648). Wilsons Prom., Vic. (Mueller, June 1853; MEL, 1006338).

P. preissianum is one of the most distinctive of the Australian species of Plocamium and is readily recognised when sterile by its robust, relatively broad thallus and series of three ramuli. The sessile, verrucose cystocarps and spermatangial areas covering ramuli are also distinctive compared to other robust species but the stichidia are rather similar to those of P. mertensii.


AGARDH, J.G. (1852). Species Genera et Ordines Algarum. Vol. 2, Part 2, pp. 337–720. (Gleerup: Lund.)

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

DE TONI, G.B. & FORTI, A. (1923). Alghe di Australia, Tasmania e Nouva Zelanda. Mem. R. Inst. Veneto Sci., Lett. Arti 29, 1–183.

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

HARVEY, W.H. (1855a). Some account of the marine botany of the colony of Western Australia. Trans. R. Ir. Acad. 22, 525–566.

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

HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)

KÜTZING, F.T. (1849). Species Algarum. (Leipzig.)

KÜTZING, F.T. (1866). Tabulae Phycologicae. Vol. 16. (Nordhausen.)

LEVRING, T. (1946). A list of marine algae from Australia and Tasmania. Acta Horti gothoburg 16, 215–227.

LUCAS, A.H.S. & PERRIN, F. (1947). The Seaweeds of South Australia. Part 2. The Red Seaweeds. (Govt Printer: Adelaide.)

LUCAS, A.H.S. (1909). Revised list of the Fucoideae and Florideae of Australia. Proc. Linn. Soc. N.S.W. 34, 9–60.

LUCAS, A.H.S. (1929b). A census of the marine algae of South Australia. Trans. R. Soc. S. Aust. 53, 45–53.

MAY, V. (1965). A census and key to the species of Rhodophyceae (red algae) recorded from Australia. Contr. N.S.W. natn. Herb. 3, 349–429.

REINBOLD, T. (1898). Die Algen der Lacepede und Guichen Bay (Siid Australien) und deren naherer Umgebung, gesammelt von Dr. A. Engelhart-Kingston. II. Nuova Notarisia 9, 33–54.

SONDER, O.G. (1845). Nova Algarum genera et species, quas in itinere ad oras occidentales Novae Hollandiae, collegit L. Preiss, Ph.Dr. Bot. Zeit. 3, 49–57.

SONDER, O.W. (1846). Algae. In Lehmann, C., Plantae Preissianae. Vol. 2, pp. 148–160. (Hamburg.)

SONDER, O.W. (1853). Plantae Muellerianae. Algae. Linnaea 25, 657–709.

WOMERSLEY, H.B.S. (1950). The marine algae of Kangaroo Island. III. List of Species 1. Trans. R. Soc. S. Aust. 73, 137–197.

WOMERSLEY, H.B.S. (1966). Port Phillip survey, 1957–1963: Algae. Mem. natn. Mus., Vict. No. 27, 133–156.

WOMERSLEY, H.B.S. (1971a). The genus Plocamium (Rhodophyta) in southern Australia. Trans. R. Soc. S. Aust. 95, 9–27.

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. 130.

Figure 130 image

Figure 130   enlarge

Fig. 130. Plocamium preissianum (A, E, F, AD, A35912; B, C, D, AD, A33242). A. Habit. B. Branch with sessile; verrucose, cystocarps. C. Branch with terminal spermatangial branchlets. D. Branchlets with spermatangia. E. Branch with axillary clusters of stichidia. F. Stichidia. [A–F as in Womersley 1971.]

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