Planktothrix Anagnostidis & Komárek, 1988

Holotype species: Planktothrix agardhii (Gomont) Anagnostidis & Komárek

Original publication and holotype designation: Anagnostidis, K. & Komárek, J. (1988). Modern approach to the classification system of cyanophytes. 3. Oscillatoriales. Archiv für Hydrobiologie, Supplement 80(1-4): 327-472, 35 figs, 13 tables.

Description: Filaments solitary, rarely in small irregular and easy disintegrating fascicles (groups) (in the mass developments), more or less straight or slightly waved, isopolar, free living; usually growing without sheath. Sheaths occur facultatively in several species, in typical planktonic species only under unfavorable conditions; they are fine, thin, colorless, joined to the trichome, opened at the apex. Trichomes with cylindrical cells, slightly constricted at the crosswalls, sometimes slightly tapering to the ends, to 4 mm long, 3.5-10 _m wide; occasionally with slight movement (trembling). Cells slightly shorter than wide to Å isodiametric, rarely slightly longer than wide, with aerotopes through the whole cell volume (but sometimes without gas vesicles in parts of trichomes); end cells (when fully developed) widely rounded or slightly narrowed and with thickened outer cell wall or with calyptra. Without chromatic adaptation, with Å constant phycobilin ratios. Presence of carotenoids myxoxanthophyll and oxillaxanthin. False branching, heterocytes and akinetes absent. Cell division crosswise, the cells grow to the original size before the next division. Meristematic zones irregular (?). Reproduction by trichome disintegration into hormogonia, by help of necridic cells. Almost all species are planktonic, few of them causing the water blooms, mainly in mesotrophic to eutrophic reservoirs (usually lakes). One species (P. cryptovaginata) grows in metaphyton of unpolluted pools and ponds among submersed aquatic plants. Two species have cosmopolitan distribution, other ones are geographically limited, mainly occurring under special ecological situations; two species are known from tropics only. Emended by Suda et al. (2002: 1592). Emended by Wang & Li (liu et al. 2013: 330).

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 feminine.

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 15 June 2024

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