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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Corallinales – Family Sporolithaceae
Thallus encrusting to warty, lumpy or fruticose, epigenous and partially to completely affixed by cell adhesion or unattached and completely free-living as rhodoliths; genicula absent. Structure pseudoparenchymatous; organisation dorsiventral in crustose portions but radial in protuberant branches; construction monomerous, consisting of a single system of branched, laterally cohering, filaments that collectively contribute to a ventrally or centrally situated core and a peripheral region where portions of core filaments or their derivatives curve outwards towards the thallus surface; cell elongation characteristics uncertain in most species; cells of adjacent filaments usually joined by both fusions and secondary pit-connections but proportions varying within and between species; epithallial cells terminating most filaments at thallus surface, distal walls usually flattened and flared; trichocytes occasional in some species; haustoria unknown.
Reproduction: Vegetative reproduction by thallus fragmentation. Gametangia and carposporangia borne in uniporate conceptacles; tetrasporangia borne in calcified compartments that may be solitary or aggregated into sori; gametangia and carposporangia formed on separate thalli from tetrasporangia. Reports of bisporangia unconfirmed.
Gametangial thalli monoecious or dioecious, carpogonia and spermatangia produced in separate conceptacles. Carpogonia terminating 2–4-celled filaments arising from the female conceptacle chamber floor and in some species also from the walls. Mature carposporophytes with carposporangia either developing more or less directly from the fertilized carpogonium or terminating short gonimoblast filaments that arise from the dorsal surface of an inconspicuous fusion cell. Spermatangial filaments branched, borne on the male conceptacle chamber floor, walls and roof.
Tetrasporangia formed within calcified compartments that may be solitary or more usually aggregated into soli of irregular shape and indefinite size, compartments interspersed amongst vegetative filaments; each mature sporangium containing cruciately arranged tetraspores and possessing an apical plug that blocks the compartmental pore prior to spore release; older sori sloughed off or becoming buried within the thallus.
Type species: S. ptychoides Heydrich 1897a: 67.
Taxonomic notes: At least 12 species have at some stage been referred to Sporolithon, and over 125 additional specific and infraspecific taxa have been recognised under the names Archaeolithothamnion and Archaeolithothamnium (Woelkerling 1988, p. 207), here considered as heterotypic synonyms of Sporolithon (see also Moussavian & Kuss 1990). Most species are poorly known (Dawson 1960a, p. 40, Woelkerling 1988, pp. 207–209, Keats & Chamberlain 1993, p. 541). Information on male, female and carposporangial stages is available only for several species (Verheij 1992, 1993a; Townsend et al. 1995), and reports of bisporangia and zonate tetrasporangia are probably incorrect (Woelkerling 1988, p. 209; Verheij 1993, p. 186). Recent accounts of the type species are provided by Verheij (1993a) and Keats & Chamberlain (1993), and additional information on the lectotype collection of S. ptychoides is given by Woelkerling (1993, p. 183). Details relating to generic etymology, nomenclature, synonymy, etc. are provided by Woelkerling (1988, pp. 203–207). Sporolithon is represented in southern Australia by one species; this account follows Townsend et al. (1995).
References:
CHAMBERLAIN, Y.M. (1993). Observations on the crustose coralline red alga Spongites yendoi (Foslie) comb. nov. in South Africa and its relationship to S. decipiens (Foslie) comb. nov. and Lithophyllum natalense Foslie. Phycologia 32, 100–115.
DAWSON, E.Y. (1960a). New records of marine algae from Pacific Mexico and Central America. Pacif. Nat. 1(20), 31–52.
HEYDRICH, F. (1897a). Corallinaceae, inbesondere Melobesieae. Ber. dt. bot. Ges. 15, 34–71, Plate 3.
MOUSSAVIAN, E. & KUSS, J. (1990). Typification and status of Lithothamnium aschersoni Schwager, 1883 (Corallinaceae, Rhodophyta) from Paleocene limestones of Egypt. A contribution to the synonymy and priority of the genera Archaeolithothamnium Rothpletz and Sporolithon Heydrich. Berl. geowiss. Abh. 120, 929–942.
TOWNSEND, R.A., WOELKERLING, W.J., HARVEY, A.S. & BOROWITZKA, M. (1995). An account of the red algal genus Sporolithon (Sporolithaceae, Corallinales) in southern Australia. Aust. Syst. Bot. 8, 85–121.
VERHEIJ, E. (1992). Structure and reproduction of Sporolithon episoredion (Adey, Townsend et Boykins) comb. nov. (Corallinales, Rhodophyta) from the Spermonde Archipelago, Indonesia. Phycologia 31, 500–509.
VERHEIJ, E. (1993a). The genus Sporolithon (Sporolithaceae fam. nov., Corallinales, Rhodophyta) from the Spermonde Archipelago, Indonesia. Phycologia 32, 184–196.
WOELKERLING, Wm.J. (1988). The Coralline Red Algae. [British Museum (N.H.): London.]
WOELKERLING, Wm.J. (1993). Type collections of Corallinales (Rhodophyta) in the Foslie Herbarium (TRH). Gunneria 67, 1–289.
The Marine Benthic Flora of Southern Australia Part IIIB complete list of references.
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.
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