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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Nemastomataceae
Thallus erect, foliose, mucilaginous. Structure multiaxial, with a cortex of discrete, subdichotomous, branch systems, usually (but not always) with gland cells, and a medulla of entangled filaments.
Reproduction: Sexual thalli monoecious or dioecious. Carpogonial branches 3-celled, borne on inner cortical cells with adjacent cells darkly staining; following fertilization the carpogonium connects with a "nutritive" auxiliary cell borne on the supporting cell, then producing several connecting filaments; non-procarpic, with auxiliary cells similarly situated to supporting cells. Gonimoblast developing outwardly from auxiliary cells, all cells of carposporophyte forming carposporangia; a distinct ostiole surrounded by modified outer cortical filaments present outside carposporophyte. Spermatangia cut off from outer cortical cells.
Tetrasporophyte heteromorphic and crustose in the type species, bearing zonately divided tetrasporangia on erect filaments. In some other species, tetrasporophytes have been reported to be isomorphic (see below), with scattered cruciately divided tetrasporangia, or unknown.
Life history triphasic with heteromorphic gametophytes and tetrasporophytes.
Lectotype species: S. dubyi (Chauvin) J. Agardh 1851: 171 ("non designatus" in the ING).
Taxonomic notes: The type species has been investigated by Ardré (1980) who demonstrated a heteromorphic life history. Other species, such as the Pacific North American species of Schizymenia monographed by Abbott (1967), with reports of isomorphic tetrasporophytes, have been shown to be incorrect by DeCew, Silva & West 1992, who suggest that the North American S. pacifica (Kylin) Kylin is probably not distinct from S. dubyi.
Typification of Schizymenia has been discussed by Parkinson (1981, p. 317).
References:
ABBOTT, I.A. (1967). Studies in the foliose red algae of the Pacific Coast II. Schizymenia. Bull. So. Calif. Acad. Sci. 66, 161–174.
AGARDH, J.G. (1851). Species Genera et Ordines Algarum. Vol. 2, Part 1, 1–336 + index. (Gleerup: Lund.)
ARDRÉ, F. (1980). Observations sur le cycle de développement du Schizymenia dubyi (Rhodophycée, Gigartinale) en culture, et remarques sur certains genres de Némastomacées. Cryptogamie, Algol. 1, 111–140.
DECEW, T.C., SILVA, P.C. & WEST, J.A. (1992). Culture studies on the relationship between Schizymenia and Haematocelis (Gigartinales, Rhodophyceae) from the Pacific coast of North America. J. Phycol. 28, 558–566.
PARKINSON, P.G. (1981). Remarks on some algal generic names recently proposed for nomenclatural conservation: Halymenia, Grateloupia, Nemastoma and Schizymenia. Taxon 30, 314–318.
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
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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