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Tribe ANTITHAMNIEAE Hommersand 1963: 330

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae

Thallus erect, with or without prostrate basal filaments, erect branches ecorticate or loosely corticated with rhizoids, bearing usually clearly separated whorls of 2, 3 or 4 whorl-branchlets from each axial cell, unbranched or pinnately branched (when distinctly pinnate, often referred to as pinnae, branches as pinnules). Growth monopodial, lateral branches arising on basal cells of whorl-branchlets; gland cells usually present, situated on short lateral branches or terminal on rachides. Cells uninucleate.

Reproduction: Gametophytes dioecious. Procarps produced successively on basal cells of whorl-branchlets at branch apices which then have limited growth, with the basal cell acting as the supporting cell and bearing a 4-celled carpogonial branch. The auxiliary cell is cut off the supporting cell and after union with the fertilized carpogonium forms an upper cell which produces one to several rounded gonimolobes, with fusions occurring between the axial cell, the lower whorl-branchlet cells and lower gonimoblast cell; carposporophytes without an involucre. Spermatangia are borne terminally on short branches on inner cells of the whorl-branchlets.

Tetrasporangia are usually sessile on cells of the whorl-branchlets or on small lateral branches of the whorl-branchlets, subspherical or ovoid, cruciately or decussately divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Taxonomic notes: The Antithamnieae is regarded as a primitive tribe of the Ceramiaceae. It was first distinguished by Hommersand who included (1963, pp. 344, 345) 11 genera, but modified by Wollaston (1968, p. 405) who separated genera into the Heterothamnieae, Warreniae and Crouanieae and retained only 5 genera in the Antithamnieae. Athanasiadis (1996) further restricts the Antithamnieae in segregating the Pterothamnieae and Perithamnieae (the latter not accepted here).

The great variety in form of the genera previously included in the Antithamnieae, particularly Lasiothallia and Ballia, indicates that these genera are better placed in separate tribes.

References:

ATHANASIADIS, A. (1996). Morphology and classification of the Ceramioideae (Rhodophyta) based on phylogenetic principles. Opera Botanica No. 128, pp. 1–216.

HOMMERSAND, M.H. (1963). The morphology and classification of some Ceramiaceae and Rhodomelaceae. Univ. Calif Pubis. Bot. 35(2), 165–366.

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.

Author: H.B.S. Womersley

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 GENERA OF ANTITHAMNIEAE

1. Thallus usually 1–30 cm high, ecorticate or corticate on lower axes, whorl-branchlets in whorls of 3 (2 in M. acanthophorum) from each axial cell; gland cell branches also bearing spermatangial or tetrasporangial clusters	MACROTHAMNION
1. Thallus 0.5–4 cm high, ecorticate, whorl-branchlets in one or two pairs from each axial cell; gland cell branches not also bearing spermatangia or tetrasporangia	2
2. Whorl-branchlets pinnate or irregularly branched, in single pairs per axial cell; gland cells on short 2–4-celled lateral branches on pinnules	ANTITHAMNION
2. Whorl-branchlets pinnate, in two pairs per axial cell, similar or different in length; gland cells terminal on the end cell of the rachides	ACROTHAMNION

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