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Electronic Flora of South Australia Species Fact Sheet

Polysiphonia atricapilla J. Agardh 1863: 1054.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Polysiphonieae

Selected citations: De Toni 1903: 934. Harvey 1863, synop.: xxii. Lucas 1909: 41; 1929b: 51. Lucas & Perrin 1947: 274. Reinbold 1897: 56. Silva et al. 1996: 537. Womersley 1979: 502, fig. 13A–D.

Thallus (Fig. 89A) dark brown-red, 4–12 cm high, much branched on all sides and densely tufted above with frequent short, patent, branchlets, with a single erect, basal axis. Holdfast discoid, rhizoidal, commonly epiphytic on Amphibolis. Structure. Basal axis suberect to very shortly prostrate, with rhizoids cut off from the lower pericentral cells. Lower main axis 0.7–1 mm in diameter with segments L/D 0.3–0.5, decreasing gradually to 400–600 µm in diameter with segments L/D 0.3–1 in mid parts and to 200–300 µm in diameter with segments L/D 0.2–0.5 in branchlets, then tapering fairly evenly to straight apices, usually with profuse trichoblasts often extending well below apices; lateral branches arising from basal cells of trichoblasts, with some cicatrigenous branches below. Pericentral cells 10–12, elongate throughout most of thallus, ecorticate; trichoblasts relatively persistent, brown, formed on every segment with a divergence of 1/4 or 1/5, commonly 1–2 mm long with (2–) 3 (–4) furcations, basal cell 45–60 µm in diameter. Rhodoplasts ribbon-shaped.

Reproduction: Gametophytes dioecious. Carposporophytes with a small, erect, basal fusion cell and branched gonimoblast bearing ovoid to clavate terminal carposporangia 30–45 µm in diameter. Cystocarps (Fig. 89B) subsessile, globular to slightly ovoid, not or slightly urceolate and with small ostiolar cells, 400–500 µm in diameter; pericarp ostiolate, 2 cells thick, outer cells isodiametric, angular. Spermatangial branches (Fig. 89C) developing as one basal branch of a trichoblast, elongate-conical, tapering from near the base, 200–450 µm long and 100–150 (–200) µm in diameter, without a sterile apical cell when mature.

Tetrasporangia (Fig. 89D) forming spiral series with a divergence of about '/s in upper, simple, not or slightly swollen branchlets, not distorting the segments, occupying about 0.3 the branch diameter when mature, subspherical, 70–100 µm in diameter.

Type from King George Sound, W. Aust. (Harvey, Alg. Aust. Exsicc. 175B); holotype in Herb. Agardh, LD, 41629).

Selected specimens: Tiparra Reef, Spencer Gulf, S. Aust., on Amphibolis, 11 m deep (Shepherd, 24.ii.1971; AD, A38235) and 6 m deep (Shepherd, 5.xi.1971; AD, A38349). Marion Bay, Yorke Pen., S. Aust., drift (Gordon-Mills, 24.v.1981; AD, A52198). Goldsmith Beach, Yorke Pen., S. Aust., on Amphibolis, drift (Womersley, 20.ix.1981; AD, A52942). Western Cove, Kangaroo I., S. Aust., on Posidonia angustifolia, 4 m deep (Lavers, 3.xii.1996; AD, A66834). Muston, American R. inlet, Kangaroo I., S. Aust., 2–3 m deep (Womersley, 2.xi.1947; AD, A6146 and 21.xi.1968; AD, A32932).


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

Distribution: King George Sound, W. Aust, to Guichen Bay, S. Australia.

Taxonomic notes: P. atricapilla is remarkably similar in habit to P. decipiens Montagne, and the type is one of Harvey's Alg. Aust. Exsicc. (175B) distributed as P. cancellata, a synonym of the latter name. P. atricapilla differs essentially in having 10–12 pericentral cells, whereas P. decipiens has 7–8. Most specimens of P. atricapilla are epiphytic on stems of Amphibolis or Posidonia, and the species may be largely confined to these hosts; however, P. decipiens also occurs on Amphibolis.

P. atricapilla was recorded by Askenasy (1888, p. 51) from St Paul I., but is described as having 12–18 pericentral cells and becoming corticated; it is not P. atricapilla.

References:

AGARDH, J.G. (1863). Species Genera et Ordines Algarum. Vol. 2, Part 3, pp. 787–1291. (Gleerup: Lund.)

ASKENASY, E. (1888). Algen. In Engler, A. (Ed.), Die Forschungsreise S.M.S. Gazelle in den Jahren 1874 bis 1876. IV Th. Bot., pp. 1–58, Plates 1–12. (Mittler: Berlin.)

DE TONI, G.B. (1903). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 3. pp. 775–1521 + 1523–1525. (Padua.)

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

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.

REINBOLD, T. (1897). Die Algen der Lacepede und Guichen Bay und deren náherer Umgebung (Slid Australien), gesammelt von Dr. A. Engelhart-Kingston. Nuova Notarisia 8, 41–62.

SILVA, P.C., BASSON, P.W. & MOE, R.L. (1996). Catalogue of the Benthic Marine Algae of the Indian Ocean. (Univ. California Press: Berkeley.)

WOMERSLEY, H.B.S. (1979). Southern Australian species of Polysiphonia Greville (Rhodophyta). Aust. J. Bot. 27, 459–528.

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

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.


Illustration in Womersley Part IIIA, 2003: FIG. 89 A–D.

Figure 89 image

Figure 89   enlarge

Fig. 89. A–D. Polysiphonia atricapilla (A, C, D, AD, A38349; B, AD, A38235). A. Habit. B. Branches with cystocarps. C. Spermatangial branches. D. Tetrasporangial branch. E–H. Polysiphonia adamsiae (AD, A35678). E. Habit. F. Cystocarp. G. Spermatangial branches. H. Tetrasporangial branches. (All as in Womersley 1979, courtesy of Aust. J. Bot.)


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