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Ceramium pusillum Harvey 1863, synop.:xlvii.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Ceramieae

Selected citations: J. Agardh 1876: 104; 1894: 21. De Toni 1903: 1458. Huisman & Walker 1990: 442. Laing 1927: 176(?). Lucas 1909: 53. Lucas & Perrin, 1947: 367. Silva et al. 1996: 402. Sonder 1881: 13. Tisdall 1898: 503. Womersley 1978: 220, figs 2B, 8.


C. nobile sensu Womersley 1948: 60; 1950: 180. (NON J. Agardh 1894=Ceramium rubrum).

Thallus (Fig. 180A) light to dark red, 1–5 (–10) cm high, with one to a few linear, straight to slightly flexuous branches usually with alternate, flabellate groups of laterals (Fig. 180A), sometimes more irregularly branched or with a few lower proliferous branchlets. Attachment by a tuft of multicellular, branched rhizoids, some descending between the cortex and lower axial cells; epiphytic on various algae. Branches 400–1000 µm in diameter below, 100–200 µm in diameter in younger branchles, tapering gradually until near the apices which are usually fairly straight (Fig. 180B). Structure. Axial cells L/D 0.6–1 (shorter near apices), becoming completely corticated close to the apices apart from a narrow separation marked by smaller cells terminating the acropetal growth, compared to slightly larger cells terminating the basipetal growth of the younger segment (Figs 180B, 182B), this separation often visible for many segments from the apices, though the acropetal and basipetal cortical cells abut each other. Periaxial cells (7–) 8–9 (–10), each cutting off two cells acropetally and basipetally (Fig. 182B), these continuing as corticating filaments often with two divisions if space permits, the cells usually angular and isodiametric at first; terminal cells of the acropetal filaments sometimes projecting slightly; the inner cortical cells enlarge but remain subspherical to ovoid. Outer cortex of small cells present, commonly forming rosettes around many of the larger inner cortical cells as well as the periaxial cells (Fig. 180C). Rhodoplasts discoid in small cells, ribbon shaped and branched in larger cells.

Reproduction: Gametophytes dioecious. Carposporophytes (Fig. 180D) usually near branch apices, globular, 200–450 µm across with 2–4 (–6) short involucral branches, carposporangia ovoid, 25–30 µm in diameter. Spermatangia (Fig. 180E) covering several segments, especially in axils of upper branches, later spreading around the branch.

Tetrasporangia (Fig. 180F) derived from the periaxial cells, forming prominent whorls of 10–15 (often including immature ones), often with some cut off later from inner cortical cells, mostly decussately divided, ovoid, 20–50 p m in diameter.

Paraspores not infrequently occur on C. pusillum.

Lectotype from Port Fairy, Vic. (Harvey); in Herb. Harvey, TCD (AIg. Aust. Exsicc. 474D).

Selected specimens: Yanchep, W. Aust., drift (Womersley, 22.ix.1979; AD, A51279). Point Peron, W. Aust., upper sublittoral (Mitchell, 22.ix.1966; AD, A30746). Head of the Great Australian Bight, S. Aust., drift (Parsons, 4.xi.1968; AD, A34182). Elliston, S. Aust., on Cystophora siliquosa, 5m deep (Shepherd, 28.x.1972; AD, A42836). Point Avoid, S. Aust., on Heterosiphonia, upper sublittoral (Ricci, 12.ii.1994; AD, A63348). Tiparra Reef, S. Aust., on Lenormandiopsis, 12m deep (Shepherd, 13.v.1982; AD, A53325). Investigator Strait, S. Aust., 34m deep (Watson, 20.i.1971; AD, A39207). Victor Harbor, S. Aust., on Gloiosaccion brownii, 6m deep (Clarke, 30.xii.1981; AD, A52845). Pennington Bay, Kangaroo I., S. Aust., on Caulerpa brownii, sublittoral fringe (Womersley, 9.x.1997; AD, A67277) and on Spyridia dasyoides, sublittoral fringe (Womersley, 29.xii.1948; AD, A10530). Robe, S. Aust., on Mychodea sp., upper sublittoral (Womersley, 18.xii.1971; AD, A41147). Carpenters Rocks, S. Aust., on Plocamium, 3–4m deep (Shepherd, 4.xii.1968; AD, A33116). Port MacDonnell, S. Aust., on ("odium fragile, drift (Womersley, 24.viii.1988; AD, A59246 -"Marine Algae of southern Australia" No. 325). Bridgewater Bay, on Laurencia elata, lower eulittoral (Beauglehole, 26.xii.1950; AD, A15615). Gabo I., Vic., on Plocamium costatum, 18m deep (Shepherd, 17.ii.1973; AD, A43507). Swansea, Oyster Bay, Tas., on Codium fragile, lower eulittoral (Skinner, 22.0.1978;

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

Distribution: Yanchep, W. Aust., to Gabo I., Vic., and around Tasmania.

Taxonomic notes: C. pusillum appears to be always epiphytic, on various algae (rarely on Posidonia) under conditions of strong water movement, especially at the outer edge of rock platforms, in the sublittoral fringe or uppermost sublittoral. Deeper growing plants (to 34m in Investigator Strait) have more irregular branching but otherwise agree with C. pusillum. In contrast, C. rubrum in Australia is characteristic of calmer waters and may be epiphytic or epilithic.

In his original description, Harvey gave three localities–"Western Australia, G. Clifton. Port Fairy, W.H.H. Warrnambool, H. Watts", but following the description he cited "Harv. Alg. Exsicc. n. 474". Accordingly Harvey's 474D in TCD from Port Fairy, Vic., is selected as lectotype of C. pusillum. A specimen from Harvey's "Travelling Set", from Port Fairy and numbered 528, is in MEL (45330), labelled by Harvey "Ceramium (Microcladia) pusillum ms". This is regarded as an isotype. Harvey's 467A in BM is probably C. pusillum, though Harvey referred to this number as C. rubrum.

Liquid preserved material of C. pusillum and C. rubrum can usually be readily identified, but dried material is often not so easily distinguished. The habit of C. pusillum, with alternately flabellate branch systems, and the habitat in strong water movement, permit field recognition. Microscopically. C. pusillum generally shows smaller terminal acropetal cells abutting larger terminal basipetal ones of the cortical filaments, even after the slight gap between the nodal cortication near the apices has closed. The subspherical to ovoid inner cortical cells with rosettes of outer cortical cells are also characteristic, in contrast to the more elongate inner cortical cells with rosettes around the periaxial cells only, in C. rubrum. Prominent rings of tetrasporangia, with sporangia much less frequently formed from the inner cortical cells, are also more characteristic of C. pusillum than of C. rubrum, though both species are variable in this respect.


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

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.)

HUISMAN, J.M. & WALKER, D.I. (1990). A catalogue of the marine plants of Rottnest Island, Western Australia, with notes on their distribution and biogeography. Kingia 1, 349–459.

LAING, R.M. (1927). A reference list of New Zealand marine algae. Trans. Proc. N.Z. Inst. 57, 126–185.

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

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

SONDER, O.W. (1881). 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.

WOMERSLEY, H.B.S. (1948). The marine algae of Kangaroo Island. II. The Pennington Bay Region. Trans. R. Soc. S. Aust. 72, 143–166, Plates 10–15.

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. (1978). Southern Australian species of Ceramium Roth (Rhodophyta). Aust. J. Mar. Freshw. Res. 29, 205–257.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia

Illustrations in Womersley Part IIIA, 1998: FIGS 180, 182B.

Figure 180 image

Figure 180   enlarge

Fig. 180. Ceramium pusillum (A, AD, A41147; B–G, AD, 33116). A. Habit of large (lower) plant and small (upper) plants. B. Young branches showing internodal spaces near apices. C. Older branch showing smaller terminal acropetal cells abutting larger basipetal cells, ovoid to subspherical inner cortical cells and rosettes of outer cortical cells (especially around periaxial cells). D. Carposporophyte. E. Spermatangial son on male plant. F. Tetrasporangia in whorls on young branches. (All as in Womersley 1978, courtesy of Aust. J. Mar. Freshw. Res.)

Figure 182 image

Figure 182   enlarge

Fig. 182. A. Ceramium rubrum (AD, A47024). Part of a branch 19-21 segments from apex, showing "dovetailing" of cortical cell filaments giving complete cortication. B. Ceramium pusillum (AD, A33116). Part of a branch 21-24 segments from apex, showing slight internodal spaces between nodal cortication. C. Ceramium lenticulare (AD, A45063). Segments of a branch showing cortical cell lineages and lenticular internodal spaces. D. Ceramium excellens (AD, A38371). Nodal cortication showing cortical cell lineages and internodal space. E. Ceramium tasmanicum (AD, A42758). Young nodal cortication showing cell lineages. (All as in Womersley 1978, courtesy of Aust. J. Mar. Freshw. Res.)

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