Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Nemaliales – Family Galaxauraceae
Selected citations: Millar 1990: 306, fig. 5A–C.
Corallina cylindrica Ellis & Solander 1786: 114, pl. 22 fig. 4.
Galaxaura cylindrica (Ellis & Solander) Lamouroux 1821: 22. May 1965: 359.
Thallus (Fig. 33E) (gametophyte) pale red to grey-red, 3–7 cm high, subdichotomously branched every 0.3–2.5 cm, branches terete, glabrous, 0.5–1.5 mm broad, occasionally regularly jointed. Holdfast discoid, 1–3 mm across; epilithic. Structure of a medulla of longitudinal filaments (3–15 µm in diameter) giving rise to radiating, dichotomously branched filaments that form the cortex (Fig. 32G) of 3–4 layers of inflated cells, innermost 18–36 µm in diameter, somewhat longer than broad, grading to outer cortical cells 9–21 µm diameter, 5–6 sided in surface view. Rhodoplasts campanulate with a central pyrenoid. Calcification present in the cortex.
Tetrasporophyte filamentous, the filaments approximately 25 µm in diameter (Magruder 1984).
Reproduction: Sexual thalli usually dioecious. Carpogonial branches (Fig. 32H) 3-celled, arising near apices in place of vegetative filaments, with the hypogynous cell (Fig. 32I) producing four large-celled branches and the basal cell four small-celled branches which develop into the involucre. Cystocarps (Fig. 33F) subspherical, 200–300 µm in diameter, gonimoblast filaments directed both towards the surface of the plant and laterally, lining the involucre and intermixing with the involucral filaments, producing terminal, obovoid, carposporangia (25–30 µm long and 10–15 µm in diameter) from all faces of the involucre. After the release of carpospores, further sporangia are produced within the old sporangial wall. Male thalli with subspherical cavities 250–300 µm in diameter, with filaments bearing terminal or lateral, obovoid, spermatangia (6–8 µm long and 4–6 µm in diameter) projecting into the cavity. After release, further spermatia are produced within the old spermatangial walls.
The tetrasporophyte with terminal or lateral, cruciately divided tetrasporangia, approximately 40 by 30 µm (Magruder 1984, fig. 24).
Type from the West Indies; lost, lectotypified by Ellis & Solander 1786, pl. 22 fig. 4 (see Papenfuss et al. 1982, p. 416).
Selected specimens: (see also Huisman & Borowitzka 1990, p. 167): Fish Hook Bay, Rottnest I., W. Aust., 7 m deep (Kraft & Huisman, 1.xii.1980; MELU, A37776–37797). Parakeet Bay, Rottnest I., W. Aust., 4 m deep (Huisman, 18.i.1986; Murdoch, JH178W). Hamelin Bay, W. Aust., 10 m deep (Huisman & Sparkes, 8.xi.1988; AD, A59811).
Distribution: Common in warmer waters. In Australia, from Hamelin Bay, W. Aust., around northern Australia to Dee Why, N.S.W.
Taxonomic notes: Until recently, the taxa Tricleocarpa cylindrica and T. oblongata (the latter not found in southern Australia) were considered to represent a single species of Galaxaura, G. oblongata. Huisman & Borowitzka (1990) found that the two species could be recognised on reproductive features and that they represented a genus distinct from Galaxaura. T. cylindrica is commonly found in tropical and subtropical seas, and extends as far south as Hamelin Bay in Western Australia.
ELLIS, J. & SOLANDER, D. (1786). The Natural History of many curious and uncommon zoophytes, collected from various parts of the globe, by the late John Ellis, Esq. F.R.S. (B.White & Son: London.)
HUISMAN, J.M. & BOROWITZKA, M.A. (1990). A revision of the Australian species of Galaxaura (Rhodophyta, Galaxauraceae), with a description of Tricleocarpa gen. nov. Phycologia 29, 150–172.
LAMOUROUX, J.V.F. (1821). Exposition Methodique des Genres de l'Ordre des Polypiers ... des Zoophytes d'Ellis et Solander. (Veuve Agasse: Paris.)
MAGRUDER, W.H. (1984). Reproduction and life history of the red alga Galaxaura oblongata (Nemaliales, Galaxauraceae). J. Phycol. 20, 402–409.
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. (1990). Marine Red Algae of the Coffs Harbour Region, northern New South Wales. Aust. Syst. Bot. 3, 293–593.
PAPENFUSS, G.F., MSHIGENI, K.E. & CHIANG, Y.-M. (1982). Revision of the red algal genus Galaxaura with special reference to the species occurring in the western Indian Ocean. Bot. Mar. 25, 401–444.
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
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.
Illustrations in Womersley Part IIIA, 1994: FIGS 32 G–I, 33E, F.
Figure 32 enlarge
Fig. 32. A–F. Galaxaura marginata (A, C, Murdoch JH 177W; B, F, MELU, A37842). A. Section of cortex of gametophyte, with fused inner cortical cells. B. Section of cortex of sporophyte. C. Section of cortex of hirsute basal part. D. Carpogonial branch with carpogonium transversely divided and sterile filaments on hypogynous and basal cells. [Mutton Bird I., Coffs Harbour, N.S.W., 5 m deep (Huisman & Millar, 6.xii.1987; MELU, wet collection)]. E. Gonimoblast filaments arising from fertilized carpogonium (as for D). F. Tetrasporangia arising laterally on smaller cortical cells. G–I. Tricleocarpa cylindrica. G. (Murdoch, JH178W). Section of cortex of gametophyte . H. Young carpogonial branch [South Passage, Lord Howe I., N.S.W., 1-3 m deep (Kraft, 2.iii.1976; MELU, wet collection)]. I. Mature carpogonial branch with sterile filaments on hypogynous and basal cells (as for H). [A–I after Huisman & Borowitzka 1990.]
Figure 33 enlarge
Fig. 33. A. Galaxaura obtusata (AD, A59812). Habit. B–D. Galaxaura marginata (B, AD, A37920; D, Murdoch, JH108W). B. Habit. C. Section of cystocarp (as for Fig. 32D). D. Section of spermatangial cavity. E, F. Tricleocarpa cylindrica (E, AD, A59811; F, MELU, wet collection, as for Fig. 32H). E. Habit. F. Section of cystocarp. [C, D, F as in Huisman & Borowitzka 1990.]
State Herbarium of South Australia