Electronic Flora of South Australia Genus Fact Sheet

Genus GIBSMITHIA Doty 1963: 458

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Dumontiaceae

Thallus erect from a crustose holdfast and in most species a simple or branched cartilaginous stalk bearing several mucilaginous fronds. Structure multiaxial, medulla of slender filaments and, rhizoids, frequently cross-linked by lateral processes; cortex of anticlinal, much branched filaments of ovoid-elongate cells, often with floridean hairs.

Reproduction: Sexual thalli monoecious or dioecious. Carpogonial and auxiliary cell branches scattered, carpogonial branches several cells long, often with sterile laterals on lower cells, carpogonium partly reflexed, hypogynous cell large. Post-fertilization carpogonium connecting with cells 3–5, then producing several connecting filaments. Auxiliary cell branches terminating in sterile vegetative cells similar to cortical filaments, with an intercalary auxiliary cell and adjacent lower cells bearing sterile laterals. Gonimoblast initials arising from auxiliary cell at site of fusion with a connecting filament, with 2–3 gonimolobes and the mature carposporophyte surrounded by lax cortical filaments, not bulging the cortex. Spermatangia cut off from distal cells of cortical filaments.

Tetrasporophytes bearing decussately cruciately divided tetrasporangia on cortical filaments.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Type species: G. hawaiiensis Doty 1963: 458, figs 1–17.

Taxonomic notes: A genus of four species (Kraft 1986), distributed in the central and western Pacific, eastern Australia, and with one species on southern Australian coasts.

Gibsmithia is a multiaxial genus differing from Kraftia in habit, presence of lateral connections between medullary and cortical filaments, lack of thick-walled hyaline hairs, and in having isomorphic generations with cruciately divided tetrasporangia.

References:

DOTY, M.S. (1963). Gibsmithia hawaiiensis gen. n. et sp. n. Pacific Sci. 17, 458–465.

KRAFT, G.T. (1986). The genus Gibsmithia (Dumontiaceae, Rhodophyta) in Australia. Phycologia 25, 423–447.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.


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