Scenedesmus Meyen, 1829
Lectotype species: Scenedesmus obtusus Meyen
Original publication: Meyen, F.J.F. (1829). Beobachtungen über einige niedere Algenformen. Nova Acta Physico-Medica Academiae Caesareae Leopoldino-Carolinae Naturae 14: 768-778, pl. XLIII [43].
Request PDFType designated in: Nägeli, C. (1849). Gattungen einzelliger Algen, physiologisch und systematisch bearbeitet. Neue Denkschriften der Allg. Schweizerischen Gesellschaft für die Gesammten Naturwissenschaften 10(7): i-viii, 1-139, pls I-VIII.
Description: Thalli single celled or colonial, forming 2- to 32-celled, usually 4- or 8-celled coenobia; surrounding mucilaginous matrix present or absent. Cells arranged linearly, alternating or in 2-3 rows, touching with the lateral walls or in subpolar region only. Cells 3-78 x 2-10 µm, nearly spherical to ellipsoidal, elongate or fusiform to elongate fusiform; cell poles capitate, obtuse, acute or long tapering. Cell wall with hemicellulosic and sporopolleninic layer, usually smooth in subgenus Acutodesmus and Scenedesmus, with submicroscopical structures in subgenus Desmodesmus, partly light microscopically visible as ribs, granulations or dents. Cells spineless or in subgenus Desmodesmus partly with sporopolleninic spines. Excretion of proteinaceous bristles. Cells uninucleate; chloroplast single and parietal with single pyrenoid. Asexual reproduction by autospores; 2-32 per sporangium, usually organized in one coenobium or disintegrated into singe cells; spore release by rupture of parental cell wall. Sexual reproduction reported for S. obliquus in subgenus Acutodesmus, but apparently extremely rare. Gametes biflagellate and isogamous; if syngamy does not occur gametes disintegrate. Chromosome numbers rarely reported, in S. quadricauda n = 11 or 13.
Information contributed by: E. Hegewald & D. Garbary; modified slightly by M.D. Guiry. The most recent alteration to this page was made on 2023-07-06 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Tsarenko, P.M. (2011). Sphaeropleales. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 280-355. Ruggell: A.R.A. Gantner Verlag K.-G..
Comments: The original description was "Alga taeniaeformis, sine thallo proprio, e cellulis ellipticis aequalibus, lateraliter in seriem planam aggregatiS formata. Sporulae massa sporacea gntmosa viridis coloris obvolutae in cellulis (sporangiis) regulariter dispositae."
Scenedesmus planktonic mainly in eutrophic freshwater ponds and lakes, rarely in brackish water; reported world-wide in all climates. Physiology and biochemistry relatively uniform, with all 28 investigated strains having hydrogenase and producing secondary carotenoids in nitrogen deficient conditions; species differ in ability to hydrolyze starch, growth under acidic conditions and guanine-cytosine content of DNA varies between 50-69% (85 investigated strains). Outer cell wall and nearly all cell wall ornamentation sporopolleninic, inner cell wall hemicellulosic. Species tolerate or prefer eutrophic water with slight acidity but only low salinity. Temperature optima at 28-30%C, but with some strains or taxa at 36%C or above. Some species of Scenedesmus highly polymorphic in culture with variation induced by various culture conditions. Culture variants may be similar to "Dactylococcus" or Lagerheimia spp. Polymorphism has been studied for about 100 years but remains incompletely understood. Variability includes cell number per coenobium/single cells, cell arrangement, cell size and especially expression of ornamentation (spines, ribs, granulation). Some species change ultrastructural features of cell walls from generation to generation based on nutrition. Genus with well defined subgeneric or infrageneric classification with many hundreds of described varieties and forma. Species distinguished mostly on differences in cell size and shape, coenobial morphology and patterns of cell wall ornamentation. Some authors include Tetradesmus as a synonym. Scenedesmus obliquus and sporadically S. obtusus are produced in mass culture and used as food because of their protein and mineral content, or used for other purposes in biochemical industry.
Verification of Data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
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=43474
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 06 July 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024
