153,560 species and infraspecific names are in the database, 20,957 images, 59,363 bibliographic items, 410,286 distributional records.

Crucigenia Morren, 1830

Holotype species: Crucigenia quadrata Morren

Original publication and holotype designation: Morren, C.F.-A. (1830). Mémoire sur un végétal microscopique d'un nouveau genre, proposé sous le nom de Crucigénie, et sur un instrument que l'auteur nomme Microsoter, ou conservateur des petites choses. Annales des Sciences Naturelles 20: 204-226, pl. XV [15].
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Precise date of publicationAugust 1830

Taxonomic status: currently recognized as a distinct genus.

Most recent taxonomic treatment adopted: John, D.M. & Tsarenko, P.M. (2002). Order Chlorococcales. In: The Freshwater Algal Flora of the British Isles. An identification guide to freshwater and terrestrial algae. (John, D.M., Whitton, B.A. & Brook, A.J. Eds), pp. 327-409. Cambridge: Cambridge University Press.

Description: Thalli colonial, forming 4-celled, square coenobia mostly 5.5-16 µm diameter, these sometimes up to 16-celled in compound coenobia; colonies flat, plate-like, embedded in structureless, gelatinous envelope. Coenobia with long axes of cells in surface view. Cells oval to lunate to triangular, 1.8-12 x 5-15 µm, fitting tightly together along adjoining walls and leaving small to conspicuous square, empty space in center. Cell walls smooth. Cells uninucleate; single chloroplast cup-shaped and parietal, with or without pyrenoid. Asexual reproduction by autospores; 4 per sporangium and organized into coenobia inside sporangia; released by rupture of parental cell wall on outer face of cell with daughter colonies rotated 45% with respect to parent colony; fragments of cell walls not a conspicuous element of colony structure except in one species (C. lauterbornii). Sexual reproduction and flagellated stages unknown. Crucigenia planktonic in variety of freshwater ecosystems including rivers and lakes, mostly in eutrophic conditions; genus essentially cosmopolitan except in polar and subpolar regions. Species distinguished based on details of cell shape and presence or absence of pyrenoid. Genus morphologically similar to Crucigeniella and Tetrastrum. The genus is biochemically characterized by occurrence of the rare polyamine norspermine and the low concentration of norspermidine; similar polyamine pattern also found in Tetrastrum but not in Crucigeniella.

Information contributed by: D. Garbary and E. Hegewald. The most recent alteration to this page was made on 27 Jan 2012 by M.D. Guiry.

Numbers of names and species: There are 49 species names in the database at present, as well as 24 infraspecific names. Of the species names, 14 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):

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Contributors
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: 11 April 2002 by M.D. Guiry

Verified by: 27 January 2012 by M.D. Guiry

Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43468

Citing AlgaeBase
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 12 November 2018.

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