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Electronic Flora of South Australia Family Fact Sheet
Phylum Rhodophyta – Class Florideophyceae
Thallus (gametophytes and some tetrasporophytes) erect, much branched radially or complanately, branches terete or compressed. Structure uniaxial, axial filament usually conspicuous throughout, subapical cells producing periaxial filaments radially and spirally arranged, or opposite, or in alternate pairs at right angles; gland (vesicular) cells present or absent; secondary pit-connections absent; pit-plugs without cap layers.
Reproduction: Gametangial thalli monoecious or dioecious. Carpogonial branches 3- or 4-celled, borne on inner cortical cells, cells of carpogonial branches with or without accessory cells. Fertilized carpogonium developing directly or after fusion with the hypogynous cell, fusion cell branched or lobed, producing branched gonimoblast filaments with terminal carposporangia, either within a cellular pericarp as a distinct cystocarp or diffuse within the cortical filaments and without a pericarp. Spermatangia cut off from cortical cells or on ovoid pedicellate structures.
Tetrasporangia (where known) lateral on filaments of tufted or prostrate tetrasporophytes, or in nemathecia on isomorphic thalli, cruciately divided.
Tetrasporophytes in some taxa isomorphic, in most taxa heteromorphic and small, filamentous, tufted or prostrate. Life history triphasic, with isomorphic or heteromorphic gametophytes and tetrasporophytes.
Taxonomic notes: The order Bonnemaisoniales was separated by Feldmann & Feldmann (1942, p. 163) from the Nemaliales on account of their then known heteromorphic alternation of generations. However, the Helminthocladiaceae (Nemaliales) are now known to be heteromorphic, and some Bonnemaisoniales are isomorphic. The Bonnemaisoniales are now recognised at ordinal level on the basis of their uniaxial structure, with subapical cells producing periaxial filaments, direct development of the gonimoblast from the fertilized carpogonium or hypogynous cell, and terminal carposporangia. The ultrastructure of the pit-plugs which lack cap layers (Pueschel 1989, p. 627) and the plastids (Chihara & Yoshizaki 1972, p. 248) are also important.
* Modifications to the key to the orders (Part IIIA, p. 20) are necessary. The couplet for 9. Bonnemaisoniales should read: "Thallus uniaxial, few to several cells thick or broad, with the axial cells cutting off 2 or 4 periaxial cells, with three pericentral cells in the ramuli; gland cells usually present; pit-plugs with no cap layers; carposporophyte with a well-developed cellular pericarp (Bonnemaisoniaceae) or diffuse in the cortex (Naccariaceae)."
References:
CHIHARA, M. & YOSHIZAKI, M. (1972). Bonnemaisoniaceae: their gonimoblast development, life history and systematics. In Abbott, I.A. & Kurogi, M. (Eds), Contributions to the systematics of Benthic Marine Algae of the North Pacific, pp. 243–252. (Jap. Soc. Phycol.: Kobe.)
FELDMANN, J. & FELDMANN, G. (1942). Recherches sur les Bonnemaisoniacées et leur alternance de générations. Ann. Sci. Nat., Sér. 11 Bot. 3, 75–175.
PUESCHEL, C.M. (1989). An expanded survey of the ultrastructure of red algal pit plugs. J. Phycol. 25, 625–636.
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 FAMILIES OF BONNEMAISONIALES
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1. Carposporophyte enclosed by a cellular pericarp forming a defined cystocarp | BONNEMAISONIACEAE |
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1. Carposporophyte diffuse, with the gonimoblast filaments ramifying between the cortical filaments and without a pericarp | NACCARIACEAE |
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