Sphacelaria Lyngbye, 1818, nom. et typ. cons.

Holotype species: Sphacelaria cirrosa (Roth) C.Agardh

Original publication and holotype designation: Hornemann, J.V. (1818). [Flora danica] 9, fasc. 27. . Havniae [Copenhagen].

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Description: Rather small (about 2-10 cm tall), usually marine, brownish to olivaceous plants, forming subglobose, hemispherical, penicillate, or complanate tufts or spreading mats; occasionally crustaceous, usually heterotrichous. Basal parts consisting of monostromatic or polystromatic discs, or of stolons and rhizoids ramifying on or penetrating into the support; rarely lacking. Terete, articulate, isodiametric, erect filaments subsimple to bushy, quite rigid to flaccid, bearing sparse to many, determinate or indeterminate, branched or unbranched, usually hemiblastic, distichous, helicoid or irregularly placed laterals. Segments cut off from the usually conspicuous cylindrical apical cell each transversely divided once preceeding longitudinal segmentation. Secondary transverse divisions in secondary segments frequent, infrequent or absent. Rhizoids on erect filaments divaricate, corticating, or absent. Hairs present or absent, often in axils of laterals. Pericysts present or absent. Many small discoid parietal chloroplasts without pyrenoids in each cell. Reproductive structures: special vegetative branchlets (propagules), plurilocular gametangia , neutral plurilocular zoidangia and unilocular zoidangia. Cosmopolitan marine in intertidal zone and in sublittoral.

Two species are known to occur in fresh water in the USA and China. Most species occur in temperate areas, some in arctic or antarctic areas or in the tropics. The diplohaplontic life history is isomorphic or slightly heteromorphic with isogamy or anisogamy. In some species there are male and female plants, while other species are probably monoecious. Occurrence of neutral plurilocular zoidangia is probable in several species. Parthenogenesis has been observed and vegetative propagation by propagules occurs in several species.

Information contributed by: W.F. Prud'homme van Reine. The most recent alteration to this page was made on 2023-10-05 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Gender: This genus name is currently treated as feminine.

Most recent taxonomic treatment adopted: Silberfeld, T., Rousseau, F. & Reviers, B. de (2014). An updated classification of brown algae (Ochrophyta, Phaeophyceae). Cryptogamie Algologie 35(2): 117-156, 1 fig., 1 table.

Comments: Both temperature and daylength have a distinct influence on the life history of Sphacelaria spp., see van den Hoek and Flinterman (1968) and Colijn & van den Hoek (1971); vegetative propagation occurs usually mainly in the warm season, while plurilocular and unilocular reproductive organs are more frequent in the colder seasons. Unattached forms occur in brackish seas (esp. the Baltic) and in seagrass meadows in temperate seas. These free-living forms usually propagate only by fragmentation. Basic chromosome number 8-12 according to Cole (1967).

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Contributors
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=32919

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 05 October 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 21 November 2024