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Electronic Flora of South Australia Species Fact Sheet

Dasyclonium incisum (J. Agardh) Kylin 1956: 534.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Polyzonieae

Selected citations: Adams 1994: 314, pl. 107 upper. Ducker et al. 1977: 87. Fuhrer et al. 1981: pl. 76. Huisman 1997: 203; 2000: 162. Huisman & Walker 1990: 433. Millar 1990: 458; 1999: 521. Millar & Kraft 1993: 52. Norris & Aken 1985: 62, fig. 28. Scagel 1962: 1026, figs 5, 20–28. Shepherd & Womersley 1971: 166; 1981: 368. Silva et al. 1996: 487. Womersley 1966: 154.


Polyzonia incisa J. Agardh 1841: 24; 1863: 1165; 1878: 32. Harvey 1849a: 71; 1858: pl. 42A; 1859b: 299; 1863, synop.: xv. Hooker & Harvey 1845: 535; 1847: 398. Kützing 1865: 3, pl. 5e, f. Reinbold 1897: 56. Sonder 1853: 703; 1855: 527; 1880: 31. Tate 1882a: 22. Tisdall 1898: 513. Wilson 1892: 166.

Euzoniella incisa (J. Agardh) Falkenberg 1901: 361, pl 5 figs 2–8, 11, pl. 14 figs 28–32. Cuoghi Costantini 1912: 183, figs 1–3. De Toni 1903: 1028. De Toni & Forti 1923: 45. Ewart 1907: 91. Guiler 1952: 106. Levring 1946: 226. Lucas 1909: 44; 1929a: 22; 1929b: 51. Lucas & Perrin 1947: 287, fig. 133. May 1949: 296; 1965: 379. Oltmanns 1922: 330, figs 539 (2–5), 544 (3–5). Scagel 1953: 70, figs 13, 14. Womersley 1950: 189.

Polyzonia incisa var. sonderi J. Agardh 1863: 1166.

Dasyclonium acicarpum J. Agardh 1894: 81.

Polysiphonia inversa Sonder 1845: 53; 1848: 180. Kützing 1849: 823; 1863: 27, pl. 87d, e.

Polysiphonia pecten Areschoug 1854: 345. J. Agardh 1863: 918. De Toni 1903: 1066. Harvey 1863, synop.: xxi. Lucas 1909: 45. Lucas & Perrin 1947: 295.

Polyzonia sonderi Harvey 1849a: 72; 1855a: 539; 1863, synop.: xv. Sonder 1880: 31. Tate 1882a: 22. Tisdall 1898: 513.

Polyzonia colensoi Hooker & Harvey ex Harvey 1849a: 71.

Polyzonia elegans var. incisa Kützing 1849: 882.

Polyzonia australis Lenormand ex Kützing 1865: 3, pl. 6a-c.

Thallus (Fig. 139A) medium to dark red-brown, lower to mid parts attached to host, above free and 0.5–5 (–10) cm long, indeterminate axes irregularly branched and bearing distichously, alternate, determinate laterals 0.5–1.2 (–1.6) mm long from each second segment; determinate laterals (Fig. 139B) pectinate, curved downwards, complanately branched with simple, exogenous, branches from each second cell, all polysiphonous to the end cells. Lateral indeterminate axes (Fig. 139B) arising endogenously from a segment above a determinate lateral, separated usually by 3 determinate laterals, occasionally developing into longer axes. Attachment by rhizoids; epiphytic on a variety of cartilaginous brown and red algae, occasionally epizoic. Structure. Apex usually slightly curved, apical cells dome-shaped, 15–20 µm in diameter. Indeterminate axes with 6 pericentral cells, (110–) 150–250 (–350) µm in diameter, segments L/D 0.7–1. Determinate laterals with 3 pericentral cells, lower branches 200–600 (–900) µm long, 45–120 (–200) µm in diameter in mid and lower parts. Segments L/D 0.4–0.8 (–1) with the cells often slightly displaced (terminally with only 2 pericentral cells and then compressed in section), tapering to a single (–2) apical cell, mucronate. Trichoblasts absent. Rhizoids usually in pairs from adjacent axial pericentral cells and within a common sheath, not cut off, with digitate haptera, ends cut off as cells. Cells uninucleate; rhodoplasts discoid, chained in larger cells.

Reproduction: Gametophytes dioecious. Procarps borne on the second segment of the basal (and sometimes next) branch of determinate laterals. Carposporophytes with a small basal fusion cell and short gonimoblast with large, ovoid, terminal carposporangia 60–1001 µm in diameter. Cystocarps (Fig. 139C) sessile, ovoid, 350–600 µm in diameter; pericarp ostiolate, ecorticate, 2 cells thick, outer cells angular and mostly L/D 1–2. Spermatangial organs (Fig. 139D) tri-radiate, developed on the lower half of the lower 1–2 branches of determinate laterals, 180–270 µm across and 250–500 (–750) µm long, each flange with a marginal row of isodiametric sterile cells.

Tetrasporangial branches (Fig. 139E) arising endogenously from the indeterminate segment above each determinate lateral, lying in the same plane, older branches developing short, cellular, outgrowths, with tetrasporangia in a straight series of 2–9, 120–180 µm in diameter with 3 cover cells each usually divided.

Type from "Nov. Holl"; holotype in Herb. Agardh, LD, 43036.

Selected specimens: Port Denison, W. Aust., on Sargassum, inner reef pools (Gordon, 8.xi.1968; AD, A33225). Yanchep, W. Aust., on Amphibolis, drift (Womersley, 22.ix.1979; AD, A51257). Point Peron, W. Aust., on Amphibolis, drift (Womersley, 18.viii.1979; AD, A51013). Elliston, S. Aust., on Pterocladia, 28 m deep (Shepherd, 23.x.1970; AD, A37475). Wanna, S. Aust., on Acrocarpia in pools (Womersley, 19.ii.1959; AD, A22450). Oedipus Point, West I., S. Aust., on Gelidium asperum, 16 m deep (Shepherd, Dec. 1966; AD, A31156). Vivonne Bay, Kangaroo I., S. Aust., on Acrocarpia, drift (Womersley, 7.x.1997; AD, A67329). Kangaroo Head, Kangaroo I., S. Aust., on Sargassum, 6 m deep (Lavers, 9.xii.1996; AD, A66833). Stinky Bay, Nora Creina, S. Aust., drift (Womersley, 26.x.1996; AD, A67113). 600 m off Middle Point, Cape Northumberland, S. Aust., on Gelidium asperum, 5 m deep (Shepherd & Johnson, 19.iii.1974; AD, A44940). Warrnambool, Vic., on G. asperum, drift (Womersley, 13.iv.1959; AD, A22915). Gabo I., Vic., on Rhodymenia, 28 m deep (Shepherd, 14.ii.1973; AD, A43354). Currie R., Tas., on Cystophora, drift (Cribb 75.3, 17.ix.1950; AD, A21026). Stapleton Point, Prosser Bay, Tas., on Carpoglossum, 3–6 m deep (Shepherd, 10.ii.1970; AD, A35744). Fluted Cape, Bruny I., Tas., on G. asperum, 10 m deep (Shepherd, 11.ii.1972; AD, A41797). Byron Bay, N.S.W., on Amphiroa anceps, 8 m deep (Silvester, 18.viii.1973; AD, A43980).

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

Distribution: Houtman Abrolhos, W. Aust., around southern Australia and Tasmania to Byron Bay, N.S.W.

New Zealand, South Africa.

Taxonomic notes: The type in LD is a small specimen in an envelope labelled "Polyzon. incisa J. Ag. in Linnaea".

The type of D. acicarpum J. Agardh, from Port Phillip Heads, Vic. (Wilson, 31.xii.1981) is in Herb. Agardh, LD, 38160, and is D. incisum. The type of Polysiphonia pecten in S, from Port Adelaide, consists of mica mounts of D. incisum, and the type of Polysiphonia inversa Sonder, from "Nov. Holl. austro occid" (Preiss) is in MEL, 1523853.

Scagel (1953) gave a detailed account of the structure and reproduction of D. incisum (as Euzoniella).


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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. 139.

Figure 139 image

Figure 139   enlarge

Fig. 139. Dasyclonium incisum (A, AD, A44940; B, AD, A43354; C–E, AD, A67329). A. Habit, on Gelidium asperum. B. Axis with pectinate determinate laterals and short indeterminate laterals. C. Cystocarps on determinate laterals. D. Spermatangial organs. E. Tetrasporangial branches arising from the segment above determinate laterals.

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