Nizymenia Sonder, 1855

Holotype species: Nizymenia australis Sonder

Original publication and holotype designation: Sonder [O.G.] (1855 '1854'). [Plantae Muellerianae] Algae annis 1852 et 1853 collectae. Linnaea 26: 506-528.

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Description: Plants reach lengths of 20 cm, are erect from a discoid holdfast, and consist of linear flattened blades 1-2 mm wide irregularly branched to several orders from the margins. Central axial cells are often indistinct at the apices, and are usually so in older fronds, in which the rhizoids obscure them. Each axial cell gives rise to 4 periaxial cells. Carpogonial branches occur in small papillae formed on the blade surfaces. Each papilla encompasses a major filament on which 1 or 2 procarpic clusters originate from certain periaxial cells. Fertile periaxial cells in turn bear 3 branched filaments, 1 of them sterile, 2 of them bearing a 3 celled, outwardly oriented carpogonial branch. One of the two carpogonial filaments also produces a lateral filament in which the hyperbasal cell is enlarged and presumably functions as the auxiliary cell. Diploidization of the auxiliary cell has not been observed, but presumably involves a short connecting filament. Cystocarps are as described for the family; carposporangia occur in chains of 4. Tetraspsorangia are as for the family; spermatangia are unknown. The carposporophyte development of the genus was documented by Searles (1968), and the tetrasporangial features described by Womersley (1971a).

Information contributed by: G.T. Kraft. The most recent alteration to this page was made on 2010-10-07 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Most recent taxonomic treatment adopted: Womersley, H.B.S. (1994). The marine benthic flora of southern Australia - Part IIIA - Bangiophyceae and Florideophyceae (Acrochaetiales, Nemaliales, Gelidiales, Hildenbrandiales and Gigartinales sensu lato). pp. [1]-508, 167 figs, 4 pls, 4 maps. Canberra: Australian Biological Resources Study.

Comments: Distribution: Frequent in drift and from shallow subtidal to over 20 m depths from South Australia to Victoria, and around Tasmania. The Nizymeniaceae is a family of 2 genera and 3 species, all endemic to southern Australia. Plants are cartilaginous, erect from discoid holdfasts, and are uniaxial, with 3-4 periaxial cells borne per central axial cell. The medulla is largely filamentous due to extensive growth of descending rhizoidal filaments from inner cells of the cortical fascicles, and the cortex is pseudoparanchymatous. Cortical rhizoids have thick walls and narrow lumens similar to the "rhizines" characteristic of the Gelidiaceae. Inner cells are multinucleate and connected by secondary pit connections. Female gametophytes are procarpic and usually polycarpogonial, the carpogonial branches forming on one or more of three filaments extending in a cluster from the thallus margin, with one of the filaments containing an intercalary auxiliary cell. The carpogonial branches are 3-celled and oriented outwardly. Following fertilization the carpogonium emits a single connecting filament, which fuses to the adjacent auxiliary cell and results in a single gonimoblast initial directed toward the thallus surface. Carposporophytes consist of gonimoblast filaments that radiate thallus-outwardly from a basal fusion cell; carposporangia form in terminal chains and are encased in an externally protruding, ostiolate pericarp. Spermatangia are formed in clusters on the upper cells of uniseriate, branched filaments that grow from surface cortical cells in localized tufts. Tetrasporangia are likewise borne on uniseriate filaments, being cruciate and sessile on the distal cells of the tufts. Tetrasporophytes and gametophytes are isomorphic.

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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 07 October 2010. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 22 June 2024

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