Planctonema, 1903: 354
Holotype species: Planctonema lauterbornii Schmidle
Original publication and holotype designation:Schmidle, W. (1903). Bemerkungen zu einigen Süsswasseraigen. Berichte der Deutschen Botanischen Gessellschaft 21: 346-355, pl. XVIII (separately).
Taxonomic status: currently recognized as a distinct genus.
Description: Filaments short, uniseriate enclosed by common mucilaginous sheath of variable thickness, without polarity and free-floating. Individual cells dispersed in loose linear arrangement, almost equidistant, or more usually cells united end to end in separate pairs. Space between pairs filled with mucilage. Cells cylindrical, containing parietal, plate-like chloroplast with(out?) pyrenoids and starch. Nucleus in median constriction of chloroplast. Vacuoles with conspicuous oil-globules marking cell poles. Vegetative propagation by fragmentation of filaments; method of sexual reproduction unknown. Planctonema planktonic in various freshwater habitats in Europe and Japan. Taxonomic position of Planctonema uncertain, with contradictory reports based on light microscopy, e.g., pyrenoid presence questionable and chloroplasts described as both axillary and parietal. In one isolate, however, ultrastructural studies showed a pyrenoid and a cell walls with two layers an inner membrane only covering individual cell, and an outer membrane surrounding adjacent cells.
NCBI Nucleotide Sequences
Numbers of names and species: There are 2 species (and infraspecific) names in the database at present, of which 1 has been flagged as currently accepted taxonomically.
Names: ('C' indicates a name that is currently 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):
Cambra Sánchez, J., Álvarez Cobelas, M. & Aboal Sanjurjo, M. (1998). Lista florística y bibliográfica de los clorófitos (Chlorophyta) de la Península Ibérica, Islas Baleares e Islas Canarias. pp. 1-614. Burgos: Asociación Española de Limnología.
Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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.
Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=43490
Cite this record as:
Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 19 May 2013.
Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:6905