Electronic Flora of South Australia Species Fact Sheet

Plocamium angustum (J. Agardh) Hooker & Harvey 1847: 404.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Plocamiaceae

Selected citations: J. Agardh 1852: 402; 1876: 343. De Toni 1900: 596. Fuhrer et al. 1981, pl. 45. Millar & Kraft 1993: 24. Sonder 1853: 682; 1855: 518. South & Adams 1979: 121, figs 1, 7–10, 26.

Synonyms

Womersley 1966: 147; 1971a: 11, figs 2–6.

Thamnophora angusta J. Agardh 1841: 10. Harvey 1844: 447.

Plocamium angustatum Kützing 1866: 17, pl. 48c-e.

P. gracile J. Agardh 1876: 345. De Toni 1900: 598. Lucas 1909: 35; 1929a: 19. Lucas & Perrin 1947: 213, fig. 78. May 1965: 372. Womersley 1950: 170. P. telfairiae sensu Guiler 1952: 90. Levring 1946: 222. May 1965: 372 [not P. telfairiae (Harvey) Kützing from Mauritius].

Thallus (Fig. 125A) to 25 cm high, with numerous, erect, slender, rather linear axes arising from the basal stolons. Axes usually 0.5–1 (–1.5) mm broad, bearing ramuli in alternating pairs, the upper often developing into a lateral branch similar to the axes; lower ramuli subulate, 1–1.5 (–2) mm long, less than 0.5 mm broad at their base, usually entire but in some plants with several small serrations or spines on the abaxial margin.

Reproduction: Sexual thalli dioecious. Cystocarps (Fig. 125B) sessile on adaxial base of ramulus or on adjacent axis, globular, smooth to slightly verrucose, 600–900 µm across. Spermatangia (Fig. 125C) covering the surface of slender ramuli near the branch apices.

Stichidia (Fig. 125D, E) in the axils of ramuli, becoming tufted and basally branched, the tufts enlarging with age and in some plants stichidia extending along the adaxial margin of the ramuli; sporangium-bearing part of stichidia usually unbranched and swollen (Fig. 125E), 60–100 µm in diameter, terete and fairly straight, the stalk remaining slender; tetrasporangia 50–70 µm long and 25–30 µm in diameter, zonately divided.

Type from "Novae Hollandiae"; lectotype in Herb. Agardh, LD, 28026.

Selected specimens: Seamount off Cannan Reefs, S. Aust., 22–30 m deep (Branden, 21.i.1991; AD, A61119). Pearson I., S. Aust., 48 m deep (Shepherd, 9.i.1968; AD, A33725). Port Willunga, S.

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

Distribution: New Zealand.

Cannan Reefs, Great Australian Bight, S. Aust., to Tuggerah Lakes, N.S.W. and around Tasmania. Common on coasts of rough to moderate wave action and known from shaded pools near low water level to 50 m.

Taxonomic notes: Aust., pool at reef edge (Womersley, 12.x.1953; AD, A19090). Snug Cove, Kangaroo I., S. Aust., 16–21 m deep (Mitchell, 16.ii.1960; AD, A24045). Pennington Bay, Kangaroo I., S. Aust., sublittoral fringe (Womersley, 23.viii.1950; AD, A13372). Amphitheatre Rock, West I., S. Aust., 13–22 m deep (Shepherd, 1.i.1969; AD, A33237). Carpenter Rocks, SE S. Aust., 3–4 m deep (Shepherd, 4.xii.1968; AD, A33111). Lady Julia Percy I., Vic., 5–8 m deep (Shepherd, 3.i.1968; AD, A32397). Red Rocks, Cowes, Phillip I., Vic., 5 m deep (AIMS-NCI, Q66C 3391-A, 12.ii.1990; AD, A60334). Gabo I., Vic., 24 m deep (Shepherd, 14.ii.1973; AD, A43306). Granville Harbour, W Tas., 3–10 m deep (Blackman, 28.i.1979; AD, A58535). Fluted Cape, Bruny I., Tas., 7–10 m deep (Shepherd, 10.ii.1972; AD, A41450). Bronte, N.S.W. (Lucas; AD, A37723). Tuggerah Lakes, N.S.W. (Lucas, April 1911; NSW).

P. angustum is usually readily recognised by its slender, rather linear axes rarely over 1 mm broad, the tufts of basally branched stichidia, and sessile cystocarps. Some intergrades to P. costatum occur however, including occasional specimens with slightly serrate ramuli.

References:

AGARDH, J.G. (1841). In historiam algarum symbolae. Linnaea 15, 1–50, 443–457.

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

FUHRER, B., CHRISTIANSON, I.G., CLAYTON, M.N. & ALLENDER, B.M. (1981). Seaweeds of Australia. (Reed: Sydney.)

GUILER, E.R. (1952). The marine algae of Tasmania. Check-list with localities. Pap. Proc. R. Soc. Tasm. 86, 71–106.

HARVEY, W.H. (1844). Algae of Tasmania. Lond. J. Bot. 3, 428–454.

HOOKER, J.D. & HARVEY, W.H. (1847). Algae Tasmanicae. Lond. J. Bot. 6, 397–417.

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. (1929a). The marine algae of Tasmania. Pap. Proc. R. Soc. Tasm. 1928, 6–27.

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.

MILLAR, A.J.K. & KRAFT, G.T. (1993). Catalogue of Marine and Freshwater Red Algae (Rhodophyta) of New South Wales, including Lord Howe Island, South-western Pacific. Aust. Syst. Bot. 6, 1–90.

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

SONDER, O.W. (1855). Algae annis 1852 et 1853 collectae. Linnaea 26, 506–528.

SOUTH, G.R. & ADAMS, N.M. (1979). A revision of the genus Plocamium Lamouroux (Rhodophyta, Gigartinales) in New Zealand. Phycologia 18, 120–132.

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. 125.

Figure 125   enlarge

Fig. 125. Plocamium angustum (A, AD, A32397; B, D, E, AD, A33111; C, AD, A33237). A. Habit. B. Branches with cystocarps. C. Ramuli covered with spermatangia. D. Branch with axillary clusters of stichidia. E. Stichidia. [A–E as in Womersley 1971.]

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