155,115 species and infraspecific names are in the database, 21,784 images, 59,948 bibliographic items, 433,667 distributional records.

Platydorina Kofoid, 1899

Empire Eukaryota
Kingdom Plantae
Subkingdom Viridiplantae
Infrakingdom Chlorophyta infrakingdom
Phylum Chlorophyta
Subphylum Chlorophytina
Class Chlorophyceae
Order Chlamydomonadales
Family Volvocaceae

Holotype species: Platydorina caudata Kofoid

Original publication and holotype designation: Kofoid, C.A. (1899). Plankton studies. III. On Platydorina, a new genus of the family Volvocidae, from the plankton of the Illinois River. Bulletin of the Illinois State Laboratory of Natural History 5(9): 419-440, pi. 38.

Taxonomic status: currently recognized as a distinct genus.

Description: Colonies flattened, slightly twisted and horseshoe-shaped with three to five posterior projections, each colony containing 16 or 32 cells arranged in one layer and oriented in different directions in a gelatinous matrix. Cells spherical or pear-shaped, each with two equal flagella, a stigma, two contractile vacuoles at the base of flagella and a massive cup-shaped chloroplast with a single basal pyrenoid. Asexual reproduction by autocolony formation, each cell of the colony dividing successively to form a plakea, which becomes a daughter colony after inversion and subsequent intercalation. Sexual reproduction anisogamous with sperm packets (bundles of male gametes). Platydorina is a freshwater genus only found in USA. Effects of various vitamins, nitrogen and carbon sources and pH on growth were investigated; only vitamin B12 stimulated growth, and a carbon source was required for anaerobic growth. A sulfated polysaccharide present in gelatinous matrix. Ultrastructure of flagellar apparatus suggested that Platydorina evolved from a Chlamydomonas-like ancestor.

Information contributed by: H. Nozaki. The most recent alteration to this page was made on 14 May 2010 by M.D. Guiry.

Numbers of names and species: There is only one species or infraspecific name in the database at present, which has 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..

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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.

Created: 17 August 2004 by M.D. Guiry

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Guiry, M.D. & Guiry, G.M. 2019. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 19 April 2019.

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