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Electronic Flora of South Australia Family Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Corallinales
Thallus mostly calcified, of varying growth form; partly to almost entirely endophytic, or growing on various substrates (epigenous) and partially to completely affixed by cell adhesion, envelopment of host axes or a crustose or rhizoidal holdfast, or growing unattached and free-living as rhodoliths; branches with alternating, uncalcified genicula and calcified intergenicula, or without genicula. Structure pseudoparenchymatous or partly to largely composed of unconsolidated or contiguous filaments; organisation usually dorsiventral and/or radial or isobilateral; construction monomerous and/or dimerous or diffuse; monomerous portions 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; dimerous portions consisting of two distinct groups of filaments/cells: a unistratose ventral or internal layer in which each filament is composed of palisade cells, non-palisade cells or both, and secondly epithallial cells or multicellular filaments arising more or less perpendicularly from cells of ventral or internal layer filaments; diffuse portions consisting of branched endophytic or epigenous filaments that usually become partially consolidated in areas of conceptacle production; walls of most vegetative cells other than genicula usually completely impregnated with calcite; cells of adjacent filaments joined by cell-fusions or secondary pit-connections or rarely both, or not interconnected; epithallial cells present in most genera, terminating most filaments at thallus surface, distal walls commonly uncalcified; haustoria present in some genera.
Reproduction: Vegetative reproduction by thallus fragmentation, apomeiotic bispores or propagules. Gametangia and carposporangia borne in uniporate conceptacles; tetrasporangia and bisporangia borne in uniporate or multiporate conceptacles; gametangia and carposporangia normally formed on separate thalli from tetrasporangia and bisporangia.
Gametangial thalli monoecious or dioecious; carpogonia and spermatangia produced in separate conceptacles or rarely in the same conceptacle. Carpogonia terminating 1–4-celled filaments arising from the female conceptacle chamber floor. Carposporophytes with carposporangia arising directly from the fusion cell or terminating short gonimoblast filaments that usually arise from a conspicuous or inconspicuous fusion cell. Spermatangial filaments unbranched or branched, restricted to the male conceptacle chamber floor, or borne on the floor, walls and sometimes the roof.
Tetrasporangia arising from the conceptacle chamber floor; each mature sporangium usually containing. four zonately arranged spores and in some non-geniculate genera producing apical plugs that individually block a pore of a multiporate conceptacle or collectively block the pore of a uniporate conceptacle prior to spore release; meiotic or apomeiotic bisporangia sometimes present.
Life history triphasic with isomorphic gametangial and tetrasporangial generations and a heteromorphic carposporangial generation.
Type genus: Corallina Linnaeus 1759: 805.
Taxonomic notes: The Corallinaceae includes eight subfamilies, all represented in southern Australia, and it contains the most diverse array of growth forms and thallus structure of any family in the Rhodophyta. While some species are more or less constant in form and structure, other species can vary greatly. Geniculate taxa are clearly multiaxial, and nongeniculate thalli or portions of thalli with monomerous construction can be interpreted as being multiaxial, and those with diffuse construction as being uniaxial. It is difficult, however, to interpret dimerous construction as being either multiaxial or uniaxial, and as a consequence, the terms uniaxial and multiaxial are not used here in describing the internal structure of non-geniculate corallines. Similarly, the terms cortex and medulla have not been used for the non-geniculate corallines (see Woelkerling & Irvine 1988, pp. 17, 18), but are for the geniculate taxa.
Macroscopically, the Corallinaceae are readily separated into geniculate and non-geniculate taxa, and although the presence or absence of genicula may not be of greater fundamental phylogenetic importance than various other characters (Cabioch 1972; Harvey & Woelkerling 1995, pp. 380, 381), it traditionally has been used as the first character in keys to subfamilies and genera (see below).
Most non-geniculate species cannot be identified solely from external features , and it is almost always necessary to examine tetrasporangial conceptacles cut vertically through the pore canal(s) to effect unequivocal determination. Most species possessing genicula, in contrast, can be identified from external features.
Nomenclatural information relating to the Corallinaceae and a summary of data on all subfamilies and tribes involving non-geniculate genera are provided by Woelkerling (1988, pp. 85–88); nomenclatural data on the subfamilies and tribes involving geniculate genera are summarised by Lebednik (1977a, p. 381), with additional data provided by Johansen & Silva (1978) and Johansen (1981). Harvey & Woelkerling (1995, p. 381, Table 3) provide a comparative summary of the diagnostic features of subfamilies as delimited here.
References:
CABIOCH, J. (1972). Étude sur les Corallinacées. II. La morphogenèse; conséquences systématiques et phylogénétiques. Cah. Biol. mar. 13, 137–288, Plates 1–12.
HARVEY, A.S. & WOELKERLING, W.J. (1995). An account of Austrolithon intumescens gen. et sp. nov. and Boreolithon van-heurckii (Heydrich) gen. et comb. nov. (Austrolithoideae subfam. nov., Corallinaceae, Rhodophyta). Phycologia 34, 362–382.
JOHANSEN, H.W. & SILVA, P.C. (1978). Janieae and Lithotricheae: two new tribes of articulated Corallinaceae (Rhodophyta). Phycologia 17, 413–417.
JOHANSEN, H.W. (1981). Coralline Algae, a first synthesis. (CRC Press: Boca Raton, Florida.)
LAMOUROUX, J.V.F. (1812). Sur la classification des Polypiers coralligenès non entièrement pierreux. Nouv. Bull. Sci. Soc. Philom. Paris 3, 181–188.
LEBEDNIK, P.A. (1977a). Postfertilization development in Clathromorphum, Melobesia, and Mesophyllum with comments on the evolution of the Corallinaceae and the Cryptonemiales (Rhodophyta). Phycologia 16, 379–406. Addendum: Phycologia 17: 358 (1978).
WOELKERLING, W.I. & IRVINE, L.M. (1988). General characteristics of nongeniculate Corallinaceae. In Woelkerling, W. J. (Ed.), The Coralline Red Algae: An Analysis of the Genera and Subfamilies of Nongeniculate Corallinaceae pp. 4–28. (British Museum (Natural History) and Oxford University Press: London and Oxford.)
WOELKERLING, Wm.J. (1988). The Coralline Red Algae. [British Museum (N.H.): London.]
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.
KEY TO SUBFAMILIES OF CORALLINACEAE
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1. Thalli non-geniculate, lacking branches composed of uncalcified genicula and calcified intergenicula | 2 |
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1. Thalli geniculate, producing branches composed of uncalcified genicula and calcified intergenicula | 6 |
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2. Tetrasporangial and bisporangial conceptacles multiporate (Figs 76E, 85A) | 3 |
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2. Tetrasporangial and bisporangial conceptacles uniporate (Figs 97E, 104E) | 4 |
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3. Cells of adjacent filaments not linked by cell-fusions (Fig. 63D, F) or secondary pit-connections (Fig. 63E) | AUSTROLITHOIDEAE |
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3. Cells of adjacent filaments linked by cell-fusions; secondary pit-connections unknown | MELOBESIOIDEAE |
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4. Tetrasporangia and bisporangia producing apical plugs (Fig. 93A) that collectively block the pore of each conceptacle prior to spore release; cells of adjacent filaments not linked by cell-fusions or secondary pit-connections | CHOREONEMATOIDEAE |
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4. Tetrasporangia and bisporangia lacking apical plugs (e.g. Fig. 98C); cells of adjacent filaments linked by secondary pit-connections and/or cell-fusions | 5 |
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5. Cells of adjacent filaments linked principally by secondary pit-connections (Fig. 63E); cell-fusions (Fig. 63D, F) absent or rare | LITHOPHYLLOIDEAE |
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5. Cells of adjacent filaments linked principally by cell-fusions; secondary pit-connections absent or rare | MASTOPHOROIDEAE |
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6. Genicula (1–) multitiered; cells of adjacent filaments linked by secondary pit-connections; cell-fusions absent or rare | AMPHIROIDEAE |
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6. Genicula with a single tier or non-tiered; cells of adjacent filaments linked by cell-fusions; secondary pit-connections absent or rare | 7 |
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7. Branches from the top of intergenicula, dichotomous, pinnate, irregularly radial or proliferous; genicula composed of a single tier of cells; mucilage on branch apices not prominent | CORALLINOIDEAE |
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7. Branches from the genicula, clustered or rarely dichotomous; genicula composed of untiered multicellular filaments; terminal intergenicula with a prominent mucilaginous cap | METAGONIOLITHOIDEAE |
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