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Grateloupia ovata Womersley & Lewis, sp. nov.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Halymeniaceae

Thallus (Fig. 61C) medium to dark red-brown, foliose, more or less ovate, 30–40 cm high and broad, 0.7–1 mm thick, mucilaginous and adhering strongly to paper, with a short stipe 1–3 cm long and a cuneate base broadening rapidly to the single, initially entire, smooth-margined frond, sometimes slightly lacerate. Holdfast discoid, 1–4 mm across; epilithic. Structure (Fig. 61D) of a cortex 20–35 (–45) µm and 4–6 cells thick, of subdichotomous chains of ovoid cells 2–3 µm in diameter, inner cells of similar diameter or slightly thicker, distant from each other, some becoming stellate, and a lax medulla of irregular filaments of very long cells 8–10 µm in diameter, with occasional cells developing refractive contents but not becoming ganglionic. Rhodoplasts discoid to elongate, few per cell.

Reproduction: Sexual thalli probably dioecious. Carpogonial branch ampullae arising in the inner cortex but situated in the outer medulla, with a few secondary and tertiary filaments 6–9 ovoid cells long and a 2-celled carpogonial branch. Auxiliary cell ampullae (Fig. 61E, F) in the inner cortex, protruding into the medulla and reaching almost to the surface, converging above, with numerous branched secondary and tertiary filaments of elongate-ovoid cells. Carposporophyte (Fig. 61D, G) ovoid, 200–350 µm across, developing 2–3 lobes from the base, carposporangia ovoid and 6–9 µm in diameter, with the ampullary filaments remaining as a moderate involucre; ostiole slight. Spermatangia unknown. Tetrasporangia unknown.

Type from Stinky Bay, Nora Creina, S. Aust., drift (Womersley, 16.v.1982); holotype and isotype in AD, A55540.

Selected specimens: The type. Margaret Brock Reef, Cape Jaffa, S. Aust., 3–5 in deep (R. Lewis, 29.xi.1972; AD, A42908). Wright Bay (N of Guichen Bay), S. Aust., drift (Shepley, 29.iii.1959; AD, A22973). N of Cape Thomas, S. Aust., drift (Womersley, 24.viii.1960; AD, A24382). Robe, S. Aust., drift (Womersley, 15.xii.1970; AD, A37821). Port MacDonnell, S. Aust., drift (G. & L. Kraft, 30.x.1986; MELU, A35237). Warrnambool, Vic., drift (Kraft, Nov. 1987; MELU, A37470).

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

Distribution: Margaret Brock Reef, S. Aust., to Warrnambool, Vic.

Taxonomic notes: Grateloupia ovata is provisionally placed in this genus largely on the thallus structure, with a relatively thin cortex and a broad medulla of lax, irregularly orientated, slender filaments. The carpogonial branch ampullae are relatively simple with few filaments, but the auxiliary cell ampullae are more branched with numerous filaments, even more so than those in G. intestinalis (see Kraft 1977c). While species with branched or proliferous foliose thalli are known in Grateloupia (e.g. G. comorinii Boergesen and G. indica Boergesen from India - see Balakrishnan 1961a), G. ovata appears to be the only species with a single, entire, ovate frond (often somewhat lacerate).

The type sheets of G. ovata are heavily infected with a fungus producing black pycni dia.


BALAKRISHNAN, M.S. (1961a). Studies on Indian Cryptonemiales - I. Grateloupia C.A. Ag. J. Madras Univ., B, 31, 11–35.

KRAFT, G.T. (1977c). The morphology of Grateloupia intestinalis from New Zealand, with some thoughts on generic criteria within the family Cryptonemiaceae (Rhodophyta). Phycologia 16, 43–51.

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

Author: H.B.S. Womersley & J.A. Lewis

Publication: 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.

Illustration in Womersley Part IIIA, 1994: FIG. 61 C–G.

Figure 61 image

Figure 61   enlarge

Fig. 61. A, B. Grateloupia intestinalis (AD, A61524). A. Habit. B. Transverse section with carposporophyte from auxiliary cell and extensive small-celled involucre. C–G. Grateloupia ovata (AD, A55540). C. Habit. D. Transverse section of thallus with a carposporophyte (displaced from ampullary filaments). E. Auxiliary cell ampulla. F. Auxiliary cell ampulla with young gonimoblast. G. Transverse section of thallus with a mature carposporophyte.

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