Electronic Flora of South Australia Genus Fact Sheet

Genus NIZYMENIA Sonder 1855: 520

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Nizymeniaceae

Thallus erect, much branched from the margins, branches flat, 2–3 mm broad, basally constricted; holdfast discoid. Structure uniaxial with four periaxial cells, the central filament soon becoming indiscernible in the dense rhizoidal medulla, with a pseudoparenchymatous cortex.

Reproduction: Sexual thalli dioecious. Carpogonial branches in small papillae on branch surfaces, each papilla with a major filament bearing 1–2 procarpic clusters. Carpogonial branches 3-celled, associated with an enlarged hyperbasal cell which acts as the auxiliary cell. Carposporophyte with a central or basal fusion cell producing radiating gonimoblast filaments terminating in chains of carposporangia, within a protruding, basally constricted cystocarp with a thick ostiolate pericarp. Spermatangia unknown.

Tetrasporangia sessile on uniseriate filaments in tufts on the branch surface, irregularly cruciately divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Type species: N. australis Sonder 1855: 521.

Taxonomic notes: Nizymenia differs from Stenocladia in that the axial filament is visible only close to the apices, not in the densely rhizoidal medulla in mature branches.

References:

SONDER, O.W. (1855). Algae annis 1852 et 1853 collectae. Linnaea 26, 506–528.

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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