|
Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Antithamnieae
Thallus 1 to 30 cm high, axes irregularly branched and corticated below with loose rhizoidal filaments; holdfast rhizoidal, epilithic or epiphytic. Axial cells each with 3 whorl-branchlets (2 in M. acanthophorum), simple or bearing a few simple pinnules, with or without minute spinous processes on upper cells; gland cells on special short branches. Cells uninucleate.
Reproduction: Gametophytes dioecious. Carpogonial branches borne on basal (= supporting) cells of whorl-branchlets, usually in a succession at branch apices, post-fertilization with rounded gonimolobes of carposporangia, partly surrounded by whorl-branchlets from below. Spermatangia terminal in clusters borne on the special gland-cell branches.
Tetrasporangia also borne on the special gland-cell branches, decussately divided.
Type species: M. pellucidum (Harvey) Wollaston 1968: 329, fig. 25.
Taxonomic notes: The genus contains 4 species, characterized by whorls of 3 (or 2) whorl-branchlets and both spermatangia and tetrasporangia borne on cells of the small special branches which bear the gland cells.
References:
WOLLASTON, E.M. (1968).Morphology and taxonomy of southern Australian genera of Crouanieae Schmitz (Ceramiaceae, Rhodophyta). Aust. J. Bot. 16, 217–417.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
KEY TO SPECIES OF MACROTHAMNION
1. Whorl-branchlets in distichous pairs from each axial cell. | M. acanthophorum |
1. Whorl-branchlets in whorls of 3 (rarely 2) from each axial cell | 2 |
2. Thallus to 30 cm high; bearing whorls of 3 unbranched whorl-branchlets from each axial cell; gland cells ( | M. pellucidum |
2. Thallus usually | 3 |
3. Thallus more or less robust, much branched, | M. secundum |
3. Thallus slender, sparsely branched, | M. pectenellum |
Email Contact: State Herbarium of South Australia |