Alexandrium Halim, 1960

Holotype species: Alexandrium minutum Halim

Original publication and holotype designation: Halim, Y. (1960). Alexandrium minutum, n. gen. n. sp. dinoflagellé provocant des "eaux rouges". Vie et Milieu 11: 102-105, 1 fig..

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Description: Thecate dinoflagellate with median cingulum, descending generally about one cingular width, lacking horns and spines. Cingular lists poorly developed. Thecal surface usually smooth, sculptured only in a few species. Apical pore plate large, with a main large comma-shaped pore, rarely narrow (oval). First apical pore plate connected (subgenus Alexandrium) or disconnected (subgenus Gessnerium) with the apical pore, with or without ventral pore. Plate formula: Po, 4', 6", 6c, 9-11s, 5"', 2"";. Nucleus elongated to horseshoe-shaped, numerous chloroplasts. Vegetative reproduction by binary fission, some species forming chains. Sexual reproduction by fusion of isogametes producing planozygotes with 2 sets of flagella which then produce a subspherical hypnozygote surrounded by hyaline mucilage. Cysts formed within the theca.

Information contributed by: M. Elbrächter. The most recent alteration to this page was made on 2024-05-31 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: Tillmann, U., Bantle, A., Krock, B., Elbrächter, M & Gottschling, M. (2021). Recommendations for epitypification of dinophytes exemplified by Lingulodinium polyedra and molecular phylogenetics of the Gonyaulacales based on curated rRNA sequence data. Harmful Algae 103: [1-16], 8 figs, 3 tables.

Comments: Forms large blooms, producing so-called red tides. Several species produce toxins like saxitoxin, gonyautoxin causing Paralytic Shellfish Poisoning (PSP). No bioluminescence is known.

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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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. 31 May 2024. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 25 June 2024

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