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Electronic Flora of South Australia Species Fact Sheet

Halicnide similans (J. Agardh) J. Agardh 1898: 206; 1899: pl. 2 fig. 13.

Phylum Rhodophyta – Family Delesseriaceae

Selected citations: De Toni 1900: 724. Guiler 1952: 101. Kylin 1924: 45, fig. 35a; 1956: 441. Lucas 1909: 37; 1929a: 20. May 1965: 401. Shepherd & Womersley 1870: 135. Silva et al. 1996: 455. Wynne 1996: 179.


Delesseria similans J. Agardh 1872: 56; 1876: 488. Sonder 1880: 24. Tisdall 1898: 509. Wilson 1892: 174.

Delesseria lyallii sensu Harvey 1859b: 311; 1863, synop.: xxxi. [NON D. lyallii Hooker & Harvey in Hooker 1847: 471, p1. 176 from the Falkland Is and Kerguelen I. = Cladodonta lyallii (Hooker & Harvey) Skottsberg 1923: 38, fig. 16.]

Thallus (Fig. 31A) light red to dark red-brown, 3–14 cm high, complanately branched usually with a single main blade (0.5–) 1–3 (–4) cm broad, bearing from the margins flat lateral blades (0.5–) 1–4 cm long and 3–10 mm broad, all blades basally constricted to a short stipe (0.2–) 0.5–1 mm in diameter; midrib becoming heavily corticated, bearing opposite lateral veins (Fig. 31B), blade margin and the older surface bearing short, spinous, multicellular filaments (Fig. 31B). Holdfast discoid, becoming stoloniferous and fibrous; epilithic. Structure. Growth by means of a dome-shaped to obconical apical cell (Fig. 31C), segmenting within 1 or 2 segments to lateral and transverse pericentral cells, the lateral cells forming second-order rows with some cells dividing irregularly to cut off third-order cells both abaxially and adaxially, forming a compact but irregular cell pattern. Original second-order rows become 2–4 axial cells apart due to intercalary divisions and form the opposite lateral veins which become heavily corticated, with the blade between veins remaining monostromatic (Fig. 31D) or becoming 3 cells thick with cortical cells on each side; thallus sectional view regular. Second-order cell rows project beyond the blade margin as prominent, branched, tapering spines (Fig. 31B) 200–300 µm long, base 80–200 µm and 3–5 (–10) cells across with corticating cells, the upper 4–8 cells uniseriate and 15–20 µm in diameter, cells isodiametric. Smaller but similar spines are formed from any marginal cells, and the veins and surface cells of older blades form, sparsely to densely, simple or occasionally basally branched, uniseriate spines mostly 90–200 (–500) µm and 6–25 cells long, 15–30 µm in diameter. Mature cells multinucleate; rhodoplasts discoid.

Reproduction: Gametophytes dioecious. Procarps scattered on blades. Carposporophytes (Fig. 31E, F) with a basal fusion cell and branched gonimoblast filaments with terminal chains of 3–5 ovoid carposporangia 15–20 µm in diameter. Cystocarps few per blade, 1–1.5 mm across, markedly swollen on both sides of the blade; pericarp (Fig. 31F) 250–350 µm thick, with compact anticlinal rows of isodiametric cells 15–20 µm in diameter, the surface cells often projecting as a short uniseriate spine. Spermatangial sori (Fig. 31G) extensive, covering most of the blades on both sides, with cortical cells dividing further and each cell producing several spermatangia.

Tetrasporangial sori (Fig. 31H) in small, compressed and ovate, marginal leaflets which develop profuse surface spines; tetrasporangia cut off from inner cortical cells on both sides, covered by smaller outer cortical cells, subspherical, 30–40 µm in diameter, with varying ages in the sorus.

Type from Georgetown, Tas. (Harvey, Alg. Aust. Exsicc. 271 I); holotype in Herb. Agardh, LD, 31740.

Selected specimens: Penguin I., Safety Bay, W. Aust., 5–6 m deep (Kraft & Borowitzka, 13.xii.1984; MELU, K7760). Pearson I., S. Aust., 10–15 m deep (Shepherd, 28.iii.1982; AD, A53051). Gulf St Vincent, S. Aust., 40 m deep (AD, A1086). Whale Point, West I., S. Aust., 25 m deep (Shepherd, June 1966; AD, A30616). Oedipus Point, West I., S. Aust., 21–25 m deep (Shepherd, 8.x.1966; AD, A30820). 13 km S of Vivonne Bay, Kangaroo I., S. Aust., 50–70 m deep (Latz, 24.xi.1968; AD, A33012). 13 km off Cape Northumberland, S. Aust., 61 m deep (Shepherd, 7.v.1975; AD, A46290). 16 km NW of Cape Bridgewater, Vic., 80–100 m deep (Johnstone & Watson, 16.v.1969; AD, A34489). Lighthouse Reef, Wilsons Prom., Vic., 2–12 m deep (O'Brien, 5.ii.1979; MELU, K6870). Point Hicks, E Vic., 18–21 m deep (Kraft & Watt, 8.ii.2001; MELU). Sarah I., Bathurst Ch., SW Tas., 2–5 m deep (Edgar, 11.iii.1995; AD, A64259). N end Governor I., Bicheno, Tas., 8–16 m deep (Edgar, 23.x.1994; AD, A63829). Waubs Bay, Bicheno, Tas., 8–12 m deep (Edgar, 23.x.1994; AD, A6381 I). Pirates Bay, Eaglehawk Neck, Tas., 9–12 m deep under kelp (Gowlett-Holmes, 31.x.1994; AD, A64058). Fortescue Bay, Tasman Pen., Tas, 2–3 m deep under kelp (Gowlett-Holmes, 22.vi.1995; AD, A64419). Charlotte Cove (Ninepin Point), Tas., 5–10 m deep (Edgar, 31.iii.1996; AD, A64793). Great Taylor Bay, Bruny I., Tas., 19 m deep (Shepherd, 14.ii.1972; AD, A42164). Tasman I., Tas., 20 m deep (Riddle, 1.iii.1990; AD, A60492).

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

Distribution: Penguin I., Safety Bay, W. Aust., and Pearson I., S. Aust., to Point Hicks, E Vic., and E and S Tasmania. Millar & Kraft (1993, p. 63) have excluded Halicnide similans from N.S.W.

Taxonomic notes: H. similans is a very distinctive alga in habit, the paired lateral veins, and the spinous filaments covering the blade margins and the surface of older blades. It is a deep-water species, most common in Tasmania where it also occurs in shallower but shaded situations; the West Australian record is of small, juvenile plants. Such juvenile plants (1–2 cm high) have basal stolons producing the erect blades which may be bare of surface spines but usually have marginal spines and relatively faint opposite veins.


AGARDH, J.G. (1872). Bidrag till Florideernes Systematik. Acta Univ. Lund 8, 1–60.

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

AGARDH, J.G. (1898). Species Genera et Ordines Algarum. Vol. 3, Part 3 - De dispositione Delesseriearum. (Gleerup: Lund.)

AGARDH, J.G. (1899). Analecta Algologica. Cont. V. Acta Univ. lund. 35, 1–160, Plates 1–3.

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

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

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. III. Flora Tasmaniae. Vol. II, pp. 282–343, Plates 185–196. (Reeve: London.)

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

HOOKER, J.D. (1847). The Botany of the Antarctic Voyage. I. Flora Antarctica. Part II, Algae, pp. 454–502, Plates 165–194. (Reeve: London.)

KYLIN, H. (1924). Studien über die Delesseriaceen. Lunds Univ. Årsskr. N.F. Avd. 2, 20(6), 1–111.

KYLIN, H. (1956). Die Gattungen der Rhodophyceen. (Gleerups: Lund.)

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. Natl 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.

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

SKOTTSBERG, C. (1923). Botanische Ergebnisse der schwedischen Expedition nach Patagonien and dem Feuerlande, 1907–1909. IX. Marine algae. 2. Rhodophyceae. K. Svenska Vetensk. Akad. Handl. 63(8), 1–70.

SONDER, O.W. (1880). In Mueller, F., Fragmenta Phytographiae Australiae. Supplementum ad volumen undecinum: Algae Australianae hactenus cognitae, pp. 1–42, 105–107. (Melbourne.)

TISDALL, H.T. (1898). The algae of Victoria. Rep. 7th Meet. Aust. Ass. Adv. Sci., Sydney, 1898, pp. 493–516.

WILSON, J.B. (1892). Catalogue of algae collected at or near Port Phillip Heads and Western Port. Proc. R. Soc. Viet. 4, 157–190.

WYNNE, M.J. (1996). A revised key to genera of the red algal family Delesseriaceae. Nova Hedwigia 112, 171–190.

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

Author: H. B. S. Womersley

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. 31.

Figure 31 image

Figure 31   enlarge

Fig. 31. Halicnide similans (A, AD, A63829; B, D, H, AD, A64793; C, AD, A33012; E, F, AD, A63811; G, AD, A60492). A. Habit. B. Apex of frond with midrib, opposite lateral veins and marginal and surface spines. C. Apex showing segmentation. D. Transverse section of midrib with monostromatic blades. E. Transverse section of young carposporophyte in thickened blade. F. Transverse section of cystocarp. G. Bladelet with spermatangial sorus. H. Bladelet with a tetrasporangial sorus.

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