163,924 species and infraspecific names are in the database, 22,783 images, 63,106 bibliographic items, 484,278 distributional records.

Alexandrium Halim, 1960

Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa (supergroup SAR)
Infrakingdom Halvaria
Phylum Miozoa
Subphylum Myzozoa
Infraphylum Dinozoa
Superclass Dinoflagellata
Class Dinophyceae
Order Gonyaulacales
Family Pyrocystaceae
Subfamily Ostreopsidoideae

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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Taxonomic status: currently recognized as a distinct genus.

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.

Taxonomic notes
Mertens & al. (2020) contend that morphological and phylogenetic data do not currently support the split of Alexandrium into four genera as advocated by Gómez & Artigas (2019). - (21 Sep 2020) - M.D. Guiry

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 16 Mar 2021 by M.D. Guiry.

Characters considered diagnostic of Alexandrium: Genre caractérisé par l'absence de plaques intercalaires dans l'épithèque, par la présence de deux intercalaires dans l'hypothèque. Thèque sphéroïdale à peu étirée en hauteur. Cingulum ouvert; sulci.ts limité à l'hypothèque. Tabulation: 4' oa, 6'', 7 g, 5''', 2p, 1''''. [Original description]

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.

Numbers of names and species: There are 42 species names in the database at present, as well as 1 infraspecific names. Of the species names, 33 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..

Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):

Click here to also show infraspecific names in the list below.

Bérard-Therriault, L., Poulin, M. & Bossé, L. (1999). Guide d'identification du phytoplancton marin de l'estuaire et du Golfe du Saint-Laurent incluant également certains protozoaires. Publication Spéciale Canadienne des Sciences Halieutiques et Aquatiques 128: 1-387.

Bérard-Therriault, L., Poulin, M. & Bossé, L. (1999). Guide d'identification du phytoplancton marin de l'estuaire et du Golfe du Saint-Laurent incluant également certains protozoaires. Publication Spéciale Canadienne des Sciences Halieutiques et Aquatiques 128: 1-387.

Steidinger, K.A. & Tangen, K. (1996). Dinoflagellates. In: Identifying Marine Phytoplankton. (Tomas, C.R. Eds), pp. 387-584. San Diego: Academic Press.

McMinn, A. & Scott, F.J. (2005). Dinoflagellates. In: Antarctic marine protists. (Scott, F.J. & Marchant, H.J. Eds), pp. 202-250. Canberra & Hobart: Australian Biological Resources Study; Australian Antarctic Division.

Verification of data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.

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.

Created: 07 May 2002 by M.D. Guiry

Verified by: 15 March 2021 by M.D. Guiry

Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=44609

Citing AlgaeBase
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 26 October 2021.

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