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Hydrolithon farinosum (Lamouroux) Penrose & Chamberlain 1993: 295.

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

Selected citations: Chamberlain 1994b: 123, figs 3A, 54,55.


Melobesia farinosa Lamouroux 1816: 315. Wilks &Woelkerling 1991: 528.

Fosliella farinosa (Lamouroux) Howe 1920: 587. Gordon et al. 1976: 255. Chamberlain 1983: 343.

Fosliella cruciata Bressan et al. 1977: 27. Jones & Woelkerling 1983: 449, figs 1,2.

Thallus encrusting, epiphytic and affixed by cell adhesion. Structure pseudoparenchymatous; organisation dorsiventral; construction dimerous, consisting of a single ventral layer of branched filaments composed of non-palisade cells, and unicellular or multicellular simple or branched filaments that arise more or less perpendicularly from cells of ventral layer filaments, each filament composed of cells 5–20 µm in diameter and 5–30 µm long; epithallial cells 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 present or absent, if present, usually occurring singly at thallus surface, not becoming buried within thallus.

Reproduction: Vegetative reproduction by propagules. Gametangia, carposporangia, tetrasporangia and bisporangia produced in uniporate conceptacles.

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 protruding above or flush with surrounding thallus surface, composed of 2 or 3 cells above the chamber, conceptacle chambers 110–125 µm in diameter and 100–120 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. Spermatangial filaments unbranched, arising from the floor of male conceptacle chambers, mature male conceptacle roofs protruding above surrounding thallus surface, conceptacle chambers 60–85 µm in diameter and 40–55 µm high.

Tetrasporangial and bisporangial conceptacle roofs protruding above surrounding thallus surface, 2 or 3 cells thick above the chamber, pore canals lined with non-protruding cells, conceptacle chambers 100–140 µm in diameter and 85–105 µm high; tetrasporangia and bisporangia usually peripheral to a central columella, sometimes scattered across the conceptacle chamber floor, mature sporangia zonately divided.

Type from the Mediterranean Sea; lectotype in CN (unnumbered); accounts of the collection have been provided by Chamberlain (1983, p. 341, fig. 19) and Penrose & Chamberlain 1993, pp. 296,297, figs 1–4).

Selected specimens: Mabel Cove, Rottnest I., W. Aust., reef pools (Woelkerling, 9.ii.1978; LTB, 12700). Point Westall (S shore), S. Aust., intertidal (Woelkerling, 16.ii.1984; LTB, 14634). Brown Beach, Kangaroo I., S. Aust., drift (Campbell & Penrose, 6.iv.1988; LTB, 15748). Vivonne Bay, Kangaroo I., S. Aust., 0–1.5 m deep (Campbell & Penrose, 8.iv.1988; LTB, 15711). Sorrento (ocean beach), Vic., reef pools (Jones, 5.iv.1982; LTB 12528).

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

Distribution: British Isles; France; Greece; Florida; Indonesia; Kenya; the Persian Gulf; the Red Sea; South Africa; Spain and tropical W. Aust. (see Penrose & Chamberlain 1993, p. 296).

In southern Australia, Point Westall, S. Aust. to Sorrento, Vic.

Taxonomic notes: H. farinosum is a cosmopolitan species that is found commonly in southern Australian waters on various algae and on the seagrass Amphibolis antarctica (see Penrose & Chamberlain (1993). Detailed accounts of the species have been provided by Gordon et al. (1976) and Penrose & Chamberlain (1993). Fosliella cruciata is considered conspecific with H. farinosum (Penrose unpubl.). Further references to synonymy have been provided by Chamberlain (1983, p. 343).


BRESSAN, G., MINIATI-RADIN, D. & SMUNDIN, L. (1977). Richerche sul genre Fosliella cruciata sp. nov. Giorn. Bot. Ital. 111, 27–44.

CHAMBERLAIN, Y.M. (1983). Studies in the Corallinaceae with special reference to Fosliella and Pneophyllum in the British Isles. Bull. Br. Mus. Nat. Hist. (Bot.) 11, 291–463.

CHAMBERLAIN, Y.M. (1994b). Mastophoroideae. In Irvine, L. M. & Chamberlain, Y. M. (Eds), Seaweeds of the British Isles. Volume 1 Rhodophyta Part 2B Corallinales, Hildenbrandiales pp. 113–158. (HMSO: London.)

GORDON, G.D., MASAKI, T. & AKIOKA, H. (1976). Floristic and distributional account of the common crustose coralline algae of Guam. Micronesica 12, 247–277.

HOWE, M.A. (1920). Class 2. Algae. In Britton, N.L. & Millspaugh,C. F.(Eds). The Bahama Flora. pp. 553–631. (Privately publ.: New York.)

LAMOUROUX, J.V.F. (1816). Histoire des Polypiers Coralligènes Flexibles. (Poisson: Caen.)

PENROSE, D. & CHAMBERLAIN, Y.M. (1993). Hydrolithon farinosum (Lamouroux) comb. nov.: implications for generic concepts in the Mastophoroideae (Corallinaceae, Rhodophyta). Phycologia 32, 295–303.

WOELKERLING, W.J. (1991). The status and disposition of Perispermon (Corallinaceae, Rhodophyta). Phycologia 30, 135–144.

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. 118.

Figure 118 image

Figure 118   enlarge

Fig. 118. Hydrolithon farinosum (A, B, LTB, 12528; C, D, LTB, 12700). A. Plants epiphytic on the seagrass Amphibolis antarctica. B. Section of tetrasporangial conceptacle containing sporangia peripherally in the chamber and a columella centrally, and with distinctive cells lining the pore canal. C. Section of spermatangial conceptacle with initials bearing spermatangia formed across the chamber floor and pore with an elongate spout. D. Section of conceptacle containing a carposporophyte with a fusion cell present in the centre of the chamber floor, gonimoblast filaments borne peripherally in the chamber at the margins of the fusion cell and bearing terminal carposporangia.

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