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Name derivation:
From the Greek ektos, external, and karpos, fruit.
Classification:
Ectocarpus Lyngbye, 1819: There are 487 species of which 75 have been taxonomically accepted. Order Ectocarpales; Family Ectocarpaceae Synonym Spongonema in PhycoKey
Morphology:
Uniseriate branched filaments, with sporangia occurring apically on short branches. Parietal chloroplasts one/cell with an irregular ribbon-shape. Unilocular (less common) and plurilocular (more common) sporangia (Dawes and Mathieson 2008). There are multiple life histories described for E. siliculosus including haploid gametophytes and sporophytes, as well as diploid gametophytes and sporophytes, and even a tetraploid sporophyte (Müeller, 1967). Such observations deviate from the classic definition of gametophytes as haploid and sporophytes as diploid. Apparently Müeller was describing the consequences of apospory, the development of sporophyte cells into diploid gametophyte cells without meiosis, and apogamy – the development of haploid sporophytes without fusion of gametes. Even so the basic life history is an isomorphic one, with haploid gametophytes only bearing plurilocular gametangia and sporophytes bearing either plurilocular (E. fasciculosis) or unilocular sporangia (E. siliculosis), each one solitary (not clustered). The unilocs are the primary site of meiosis in the sporophyte, and its haploid zoospores produce gametophytes. By contrast, the plurilocular sporangia on the sporophyte produce diploid zoospores that recycle the sporophyte (A. Mathieson, personal communication).
Similar genera:
Pylaiella, Hincksia. Botrytella differs in having numerous small discoid chloroplasts per cell, and unilocular gametangia and sporangia in clusters.
Habitat:
Occurs worldwide in marine environments. Can be found growing on rocks or on other seaweeds and can be a nuisance fouling organism on ships and in mariculture.
References:
Dawes, C.J. and A.C. Mathieson 2008. Seaweeds of Florida. University Press of Florida (592 pp). Graham, L. and L. Wilcox 2000. Algae. Prentice-Hall; Taylor, W. R. 1957. Marine Algae of the Northeastern Coast of North America. Revised edition. Univ. Michigan Press., Ann Arbor, ix + 509 pp. Guiry, M.D., and G.M. Guiry 2016. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 16 January 2013. Lyngbye, H.C. 1819. Tentamen hydrophytologiae danicae continens omnia hydrophyta cryptogama Daniae, Holsatiae, Faeroae, Islandiae, Groenlandiae hucusque cognita, systematice disposita, descripta et iconibus illustrata, adjectis simul speciebus norvegicis. pp. [i]-xxxii, [1]-248, 70 pls. Hafniae [Copenhagen]: typis Schultzianis, in commissis Librariae Gyldendaliae. Müller, D.G. 1967. Generationswechsel, Kernphasenwechsel and Sexualitätder Braunalge Ectocarpus siliculosus im Kulturversuch. Planta (Berlin) 75: 39-54.