Rhipidothamnion secundum gen. et sp. nov. and Spermothamnion miniatum sp. nov. (Ceramiaceae, Rhodophyta) from eastern Australia
Huisman, J.M. (1985) Rhipidothamnion secundum gen. et sp. nov. and Spermothamnion miniatum sp. nov. (Ceramiaceae, Rhodophyta) from eastern Australia. Phycologia, 24 (1). pp. 55-66.
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Rhipidothamnion secundum gen. et sp. nov. and Spermothamnion miniatum sp. nov. are described from eastern Australia. Rhipidothamnion, from One Tree Island, Queensland, and Coffs Harbour, NSW, produces both prostrate and erect axes. Erect axes branch secundly to produce a fan-shaped thallus. Procarps are formed on the subterminal cells of upright axes, from which three pericentral cells are produced, the second-formed acting as the supporting cell. After fertilization an auxiliary cell is cut off from the supporting cell and receives the diploid nucleus via a small connecting cell. Four gonimoblast initials are produced and a large fusion cell is formed comprising the subapical, supporting and auxiliary cells. Carpospores arise from the terminal cells of the gonimoblast filaments. An involucre is produced from the sterile cells of the procarp. Tetrahedral tetrasporangia are formed adaxially on cells of the upright axes, as are spermatangial heads. Rhipidothamnion is included in the tribe Spermothamnieae on the basis of its vegetative structure. The production of an inner involucre relates the genus to the tribe Sphondylothamnieae, but this character is thought to be present in a common ancestor to both tribes. Spermothamnion miniatum sp. nov., from Lord Howe Island, NSW, differs from other species of Spermothamnion in the production of involucral branches from the cell below the subhypogenous cell rather than the subhypogenous cell itself. The remaining aspects of the female reproductive system appear similar to that known for other species of Spermothamnion, with the exception of producing only one gonimoblast initial per auxiliary cell rather than 3–4. The inclusion of S. miniatum in Spermothamnion necessitates returning to the original circumscription of the genus Tiffaniella, and only including those plants lacking involucral branches altogether.
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|Publisher:||International Phycological Society|
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