Gyrodinium Kofoid & Swezy, 1921, nom. cons.

Holotype species: Gyrodinium spirale (Bergh) Kofoid & Swezy

Original publication and holotype designation: Kofoid, C.A. & Swezy, O. (1921). The free-living unarmored Dinoflagellata. Memoirs of the University of California 5: i-viii, 1-562.

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Description: Small-to-large (<5-<200 µm) unarmored unicellular free-living, predominantly motile flagellates, sometimes enclosed in temporary cysts. Cells globular to fusiform, often dorsiventrally, rarely laterally compressed, with well-developed cingulum and sulcus, transverse and longitudinal flagella. Cingulum displaced at least 1/5 of total body length (for less cingulum displacement, see Gymnodinium). Cingulum with one turn to 1.5 turns if the cell shows torsion (for greater torsion, see Cochlodinium). Sulcus restricted to hypocone or extending to the epicone. Amphiesma delicate to rigid, smooth or with conspicuous striae on hypocone or extending to epicone. Number on epicone may be larger than on hypocone. Typical dinokaryon in some species enclosed by a perinuclear sheet, visible by light microscopy. Chloroplasts absent or present, some species with chloroplast pigments typical for prymnesiophytes, lacking the dinoflagellate pigment peridinin; pigments of other species with unusual chloroplast color not analyzed. Some species with stigma. Cytoplasm either colorless or of various colors. Nutrition phototrophic, mixotrophic, phagotrophic, or by absorption of dissolved organic material. Some species produce temporary cysts by secreting hyaline sheets, and may be confused with coccoid dinophytes. Vegetative reproduction by binary fission, sexual reproduction, including the production of hypnozygotes acting as resting cysts, known for some species. Cosmopolitan, marine, brackish and freshwater; some species inhabit snow and ice. Several species form large blooms. Gyrodinium aureolum Hulburt or a similar species, assigned also to Gymnodinium cf. nagasakiense Takayama and Adachi, produces ichthyotoxins of economic importance. Emended by G. Hansen & Moestrup (2000: 312).

Information contributed by: M. Elbrächter. The most recent alteration to this page was made on 2024-06-13 by M.D. Guiry.

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

Most recent taxonomic treatment adopted: Moestrup, Ø. & Calado, A.J. (2018). Süßwasserflora von Mitteleuropa. Dinophyceae. Vol. 6 pp. [i]-xii, [1]-560, 421 figures. Berlin: Springer Spektrum.

Comments: Problems with identification This is clearly an artificial genus for when Kofoid & Swezy (1921) set it apart from the genus Gymnodinium the main criterion was that the girdle is displaced more than one fifth the length of the body. Consequently, identification of members of this genus can be problematical since the shape frequently changes under the microscope and with fixation. Shape can also be affected by changes in salinity. It is also difficult to separate this genus from Gymnodinium. Bursa (1962) has shown that Gyrodinium californicum Bursa divides to give two daughter cells one resembling a Gyrodinium , the other a Gymnodinium. Kimball & Wood (1962) working with an organism identified as Gymnodinium mirabile Penard noted different forms resembling Gymnodinium fissum (Levander) Kof. & Swezt, Gyrodinium nelsoni Martin in culture. Gyrodinium aureolum was found to become Gymnodinium like on preservation and when left in continuous dark (Braarud & Heimdal, 1970). According to Daugberg et al. (2000: 312), Gymnodinium aureum Kofoid & Swezy belongs to Gyrodinium as emended by them.

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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. 13 June 2024. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 16 July 2024

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