Clastidium Kirchner, 1880

Holotype species: Clastidium setigerum O.Kirchner

Original publication and holotype designation: Kirchner, O. (1880). Beiträge zur Algenflora von Württemberg. Jahreshefte des Vereins für vaterländische Naturkunde in Württemberg 36: 155-203, pl. II.

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Description: Unicellular; solitary elongated cells, rarely grouped together, joined more or less perpendicularly by one (basal) end to the substrate, usually to filamentous algae or submerged aquatic plants. Cells always polarized, attached to the substrate by the narrowed mucilaginous pad, on the apical end also narrowed and prolonged into thin mucilaginous hair-like string (sometimes long); cell-form widely oval, ellipsoidal, ovoid or pear-shaped, rarely slightly club-shaped. Around cells sometimes thin, mucilaginous, often diffluent, colorless sheaths (pseudovaginae), which open at the top during the cell division. Cell content pale blue-green, usually without visible granules, always without aerotopes. Cells divide first asymmetrically in their apical parts, later successively or almost spontaneously always perpendicular to the long axis of a cell, sometimes forming a row of daughter cells (exocytes) at the apical end, from which they escape and join again to the substrate; sometimes remains the basal part of the cell undivided and further divisions proceed successively only in the upper part of the cell. The basal sterile part can grow and divide again at its apical end. Whole elongated cell rarely divides into daughter cells - exocytes. Young cells develop first with rounded apex, apical mucilaginous strings form later.. All species are known from clear, streams or stagnant mountain waters, the commonest (and probably cosmopolitan) C. setigerum grows on algae and plants, C. rivulare usually on stones in European mountain areas; C. sisyoideum only known from Chinese mountains. One species is known from Arctic Canadian lakes.

Information contributed by: J. Komárek. The most recent alteration to this page was made on 2023-03-03 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 neuter.

Most recent taxonomic treatment adopted: Strunecký, O., Ivanova, A.P. & Mares, J. (2022 '2023'). An updated classification of cyanobacterial orders and families based on phylogenomic and polyphasic analysis (Review). Journal of Phycology 59(1): 12-51.

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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.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 03 March 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 25 June 2024

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