Electronic Flora of South Australia Genus Fact Sheet
Phylum Phaeophyta – Order Chordariales – Family Spermatochnaceae
Thallus irregularly subdichotomous, haplostichous, slender, 0.5–1 mm in diameter below, tapering above, 5–50 cm long. Branch apices with 4–5 axial filaments showing apical growth. Medulla with the 4–5 axial filaments separating laterally, becoming hollow. Cortex 2–4 cells thick, becoming pseudoparenchymatous with large inner cells becoming elongate, and successively smaller outer cells with a smooth surface between the assimilatory tufts. Primary assimilatory filaments formed close to apices, separating as the cortical cells enlarge, with secondary assimilatory filaments developing from adjacent cortical cells to form tufts of filaments each 4–10 cells long, with associated phaeophycean hairs and sporangia.
Reproduction: Reproduction by uniseriate plurilocular sporangia with 4–10 locules producing mitospores, and ovoid unilocular sporangia producing meiospores which form dioecious gametophytes with isogametes; direct reproduction of both macrothalli and microthalli occurs (Novaczek et al. 1986; Peters & Müller 1986).
Life history diplohaplontic and heteromorphic, or direct, with the sporophytic macrothallus producing unilocular sporangia with meiospores and plurilocular sporangia with mitospores. Gametophyte filamentous (Dangeard 1968).
Type species: S. rhizodes (Turner) J. Agardh, type cons.
Taxonomic notes: A genus of four species (Kylin 1940, p.53), distinguished from related genera by the presence of 4–5 apical cells and a smooth cortex between the assimilatory tufts.
AGARDH, J.G. (1841). In historiam algarum symbolae auctore. Linnaea 15, 1–50, 443–457.
DANGEARD, P. (1968). Sur le développement du Stilophora rhizodes (Ehr.) J. Agardh. Botaniste 51, 95–116.
KYLIN, H. (1940). Die Phaeophyceenordnung Chordariales. Acta Univ. lund. N.F. Avd. 2, 36(9), 1–67, Plates 1–8.
NOVACZEK, I., BIRD, C.J. & McLACHLAN, J.L. (1986). Culture and field studies of Stilophora rhizodes (Phaeophyceae, Chordariales) from Nova Scotia, Canada. Br. phycol. J. 21, 407–416.
The Marine Benthic Flora of Southern Australia Part II complete list of references.
Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
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