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Hydrolithon rupestris (Foslie) Penrose, comb. nov.

Phylum Rhodophyta – Class Florideophyceae – Order Corallinales – Family Corallinaceae – Subfamily Mastophoroideae


Lithophyllum rupestre Foslie 1907a: 26. Woelkerling & Campbell 1992: 100.

Mesophyllum rupestre (Foslie) Adey 1970: 26.

Thallus encrusting or warty, 0.15–4 mm thick, epilithic or epizoic and affixed by cell adhesion. Structure pseudoparenchymatous; organisation dorsiventral; construction monomerous, consisting of a single system of branched filaments that collectively contribute to a ventrally situated core, and a peripheral region where portions of core filaments or their derivatives curve outwards towards the thallus surface, each filament composed of cells 2–6 µm in diameter and 2–17 pin long; a single epithallial cell terminating most filaments at the thallus surface, distal walls rounded or flattened but not flared; cells of adjacent filaments joined by cell-fusions, secondary pit-connections absent; trichocytes occurring commonly at thallus surface, arranged in horizontal fields or singly, not becoming buried within the thallus.

Reproduction: Vegetative reproduction unknown. Gametangia, carposporangia and tetrasporangia produced in uniporate conceptacles; bisporangia unknown.

Gametangial plants monoecious; carpogonia and spermatangia produced in separate conceptacles. Carpogonia terminating 3-celled filaments arising from the female conceptacle chamber floor. Mature female-carposporangial conceptacle roofs flush with surrounding thallus surface, usually composed of 3 cells above the chamber, conceptacle chambers 77–104 µm in diameter and 63–90 µm high. Carposporophytes developing within older female conceptacles after karyogamy, when mature composed of a large central fusion cell and gonimoblast filaments bearing terminal carposporangia, pore canals formed perpendicularly to thallus surface. Spermatangial filaments unbranched, arising from the floor of male conceptacle chambers, mature male conceptacle roofs flush with surrounding thallus surface, composed of 3 or 4 cells, conceptacle chambers 49–55 µm in diameter and 41–49 µm high.

Tetrasporangial conceptacle roofs flush with surrounding thallus surface, 3 or 4 cells thick above the chamber, pore canals lined with non-protruding cells, conceptacle chambers 82–96 µm in diameter and 82–77 µm high; tetrasporangia scattered across chamber floor, each mature sporangium 15–35 µm in diameter and 40–55 µm long, zonately divided.

Type from Phillip I., Vic. (C. J. Gabriel, iv 1905); holotype in TRH; illustrated by Penrose (1990, fig. 54A–D).

Selected specimens: Lucky Bay, Cape Le Grand, W. Aust., 0–3 m deep (Woelkerling, Platt & Jones, 9.ii.1984; LTB, 14344). Dempster Point, Israelite Bay, W. Aust., intertidal (Woelkerling, Platt & Jones, 8.ii.1984; LTB, 14259, 14262). 10 km E of Eyre, W. Aust., 0–1.2 m deep (Woelkerling, Platt & Jones, 9.ii.1984; LTB, 14127). Point Fowler (E shore), S. Aust., 2–3 m deep (Woelkerling, Platt & Jones, 14.ii.1984; LTB, 14465). Point Westall, S. Aust. (Platt & Jones, 16.ii.1984; LTB, 14564). Elliston, S. Aust. (Turner, 2.xi.1986; LTB, 15412). Beachport (Post Office Rock), S. Aust., 0–3 m deep (Campbell & Penrose, 6.xi.1987; LTB, 15844). Cape Cassini, Kangaroo I., S. Aust., 0–2 m deep (Penrose, 3.iv.1988; LTB, 15612). Stokes Bay, Kangaroo I., S. Aust., 0–2 m deep (Campbell & Penrose, 4.iv.1988; LTB, 15603). Vivonne Bay, Kangaroo I., S. Aust., 0–1.5 m deep (Campbell & Penrose, 8.iv.1988; LTB, 15714). Rye (ocean beach), Vic., tide pools (Woelkerling, 14.ii.1977; LTB, 12488). Sorrento (ocean beach), Vic., reef pools (Woelkerling, 5.xii.1976; LTB, 12507).

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

Distribution: Lucky Bay, W. Aust., eastwards to Phillip I., Vic., and from Cape Green, southern N.S.W.

Taxonomic notes: H. rupestris occurs commonly on intertidal rock platforms in southern Australia. Additional information on the species has been provided by Penrose (1990).


ADEY, W.H. (1970). A revision of the Foslie crustose coralline herbarium. K. norske Vidensk. Selsk. Skr. 1970 (1), 1–46.

FOSLIE, M. (1907a). Algologiske notiser. III. K. norske Vidensk. Selsk. Skr. 1906(8), 1–34.

PENROSE, D.L. (1990). Taxonomic studies on Spongites and Neogoniolithon (Corallinaceae, Rhodophyta) in southern Australia. Unpublished PhD Thesis, La Trobe University, Bundoora, Victoria, Australia.

WOELKERLING, W.J. & CAMPBELL, S.J. (1992). An account of southern Australian species of Lithophyllum (Corallinaceae, Rhodophyta). Bull. Br. Mus. Nat. Hist., Bot. Ser. 22, 1–107.

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

Author: D.L. Penrose

Publication: Womersley, H.B.S. (28 June, 1996)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIB. Gracilarialse, Rhodymeniales, Corallinales and Bonnemaisoniales
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIB 1996, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustration in Womersley Part IIIA, 1996: FIG. 121.

Figure 121 image

Figure 121   enlarge

Fig. 121. Hydrolithon rupestris (A, LTB, 15603; B, C, LTB, 14564). A. Epilithic plants. B. Section of tetrasporangial conceptacle with sporangia across the chamber floor and elongate cells lining the pore canal. C. Section of thallus showing scattered tetrasporangial conceptacles and the regularity in the shape and size of cells.

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