Dictyosphaerium Nägeli, 1849

Holotype species: Dictyosphaerium ehrenbergianum Nägeli

Original publication and holotype designation: 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.

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Description: Thalli forming free-floating, spherical to irregular colonies with 4 to 64 cells embedded in a common envelope, 10-100 µm in diameter. Cells perpendicular to colony surface, attached to the ends of thin stalks emerging from center of colony and branching dichotomously or tetrachotomously. Cells spherical to oval to ellipsoid or cylindrical, 1-10 µm in diameter or length. Cell walls typically smooth, roughened in one species; spines absent. Cells uninucleate; chloroplasts parietal and cup-shaped, generally single in vegetative cells, often two in mature or dividing cells; pyrenoids single per chloroplast. Asexual reproduction by autospores, 2 or mostly 4 per sporangium. Mother cells typically divide in two perpendicular planes also perpendicular to thallus surface. Spores release after rupture of parental cell and become attached to parental wall remnants; cell wall remnants develop into mucilaginous stalks. Large colonies result from multiple cycles of autospore formation. Zoospores reported by some early authors but poorly documented and considered absent by recent specialists. Sexual reproduction oogamous, reported only in D. indicum. Male gamete elongate with two apical flagella. Dictyosphaerium common and probably cosmopolitan in a variety of freshwater habitats soil. In eutrophic reservoirs and fishponds green water blooms may occur. At the end of the growing season colonies break up, forming single cells that later regenerate new thalli. Specialized dilute and low pH media have been developed for growth of particular Dictyosphaerium spp. A segregate genus, Pseudodictyosphaerium, characterized by the absence of pyrenoids. Emended by Bock et al. (2011: 640).

Information contributed by: F. Hindák & D. Garbary. The most recent alteration to this page was made on 2011-12-20 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). Trebouxiophyceae. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 61-108. Ruggell: A.R.A. Gantner Verlag K.-G..

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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=43503

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 20 December 2011. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 04 December 2022

 
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