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Genus ACROTHAMNION J. Agardh 1892: 23

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Antithamnieae

Thallus one to a few cm high, with prostrate and erect indeterminate axes, ecorticate, bearing whorls of 4 pinnae (usually 2 larger and 2 smaller) each usually with a shorter basal cell and with opposite unbranched pinnules from each rachis cell; gland cells terminal on the rachis of the pinnules. Attachment of prostrate axes by rhizoids with terminal haptera; epiphytic.

Reproduction: Gametophytes dioecious. Procarps in series of 4–8 on indeterminate axes, with 4-celled carpogonial branches on the basal (supporting) cells of the pinnae. Post-fertilization the supporting cell cuts off upwards an auxiliary cell and a terminal gonimolobe forms followed by lateral gonimolobes, with slight fusion of the axial cell, residual supporting cell, and lower gonimoblast cells; the carposporophyte is partly enclosed by pinnae from lower axial cells. Spermatangia occur in branched clusters of cells on cells of the pinnules.

Tetrasporangia occur on protrusions from the basal cells of major pinnae, cruciately divided.

Type species: A. pulchellum (Harvey) J. Agardh 1892: 25 [= A. preissii (Sonder) Wollaston 1968: 323].

Taxonomic notes: A genus of 2 species (see Wollaston 1977b, p. 391), one from southern Australia. (Wollaston 1977b) and one from the West Indies, Solomon Is, and Japan (Itono 1977, p. 22).


AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.

ITONO, H. (1977). Studies on the Ceramiaceous algae (Rhodophyta) from southern parts of Japan. Bibliotheca Phycologia 35, 1–499.

WOLLASTON, E.M. (1968).Morphology and taxonomy of southern Australian genera of Crouanieae Schmitz (Ceramiaceae, Rhodophyta). Aust. J. Bot. 16, 217–417.

WOLLASTON, E.M.(1977b). Morphology and taxonomy of the genus Acrothamnion J. Ag. (Ceramiaceae, Rhodophyta). Bull. Jap. Soc. Phycol. 25, suppl., 385–393.

The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.

Author: E.M. Wollaston & 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
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