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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Family Delesseriaceae
Thallus erect, much branched endogenously from the axial cells of the midrib, blades monostromatic apart from the corticated midrib, with lateral microscopic veins; holdfast discoid or stoloniferous. Structure. Apical cell segmenting to give first 2 lateral (later 2 transverse) pericentral cells with the second-order row producing third-order rows abaxially from each cell, with intercalary cells cutting off laterally short rows of fourth-order cells which are arranged irregularly in the monostromatic wings. Second- and outer third-order rows only reaching the blade margin, with second-order cells (sometimes third-order cells) enlarging and the rows forming the microscopic lateral veins. Cortication of the midrib by cells cut off the transverse pericentral cells, later from the lateral pericentral cells, forming descending rhizoids, with the axial and pericentral cells remaining clear in transverse section of older midribs.
Reproduction: Gametophytes dioecious. Procarps developed on transverse pericentral cells on both sides of bladelets, with 2 sterile cells and a 4-celled carpogonial branch. Carposporophytes with a basal fusion cell, much branched gonimoblast, and terminal carposporangia that mature sequentially. Cystocarps ovoid to hemispherical, ostiolate, with or without a neck, pericarp 3–5 cells thick. Spermatangial sori on both sides of bladelets, with or without a sterile midrib, in striae between the lateral veins or spreading over the bladelet, with the primary cells cutting off initials with outer spermatangia.
Tetrasporangial sori on both sides of bladelets, with or without a sterile midrib, with tetrasporangia cut off from second- and third-order cells and later from inner cortical cells, with a cortex 2 cells thick.
Lectotype species: A. ruscifolium (Turner) J. Agardh 1898: 190. See Kylin 1923: p. 83, figs 53–60; Maggs & Hommersand 1993: 203, fig. 65.
Taxonomic notes: A genus of some 7 species, the type, A. spathulatum (Sonder) Womersley & Shepley from southern Australia, A. unguiculescens Millar (1990, p. 425, fig. 51E–H) from N.S.W., A. minimum Yamada (1944, p. 13) from Japan, A. gregarium (Dawson) Wynne (1985b, p. 169) from the Gulf of California, southern California and the Hawaiian Is, and A. montagneanum (J. Agardh) J. Agardh and A. oppositifolium (Harvey) J. Agardh from New Zealand (see Adams 1994, p. 280).
References:
ADAMS, N.M. (1994). Seaweeds of New Zealand. (Cant. Univ. Press: Christchurch.)
AGARDH, J.G. (1898). Species Genera et Ordines Algarum. Vol. 3, Part 3 - De dispositione Delesseriearum. (Gleerup: Lund.)
KYLIN, H. (1923). Studien über die Entwicklungsgeschichte der Florideen. K. Svenska Vetensk Akad Handl. 63, 1–139.
MAGGS, C.A. & HOMMERSAND, M.H. (1993). Seaweeds of the British Isles. Vol. 1. Rhodophyta. Part 3A, Ceramiales. (HMSO: London.)
MILLAR, A.J.K. (1990). Marine Red Algae of the Coffs Harbour Region, northern New South Wales. Aust. Syst. Bot. 3, 293–593.
WYNNE, M.J. (1985b). Taxonomic notes on some Delesseriaceae (Rhodophyta) occurring in southern California and Mexico. Bull. S. Calif. Acad. Sci. 84, 164–171.
YAMADA, Y. (1944). Notes on some Japanese Algae X. Sci. Pap. Inst. Algol. Res. Fac. Sci., Hokkaido Imp. Univ., III, No. 1, 11–25.
The Marine Benthic Flora of Southern Australia Part IIID complete list of references.
Publication:
Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.
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