Phacotus Perty, 1852: 162
Holotype species: Phacotus viridis Perty
Currently accepted name for the type species: Phacotus lenticularis (Ehrenberg) Deising
Original publication and holotype designation:Perty, M. (1852). Zur Kenntniss kleinster Lebensformen: nach Bau, Funktionen, Systematik, mit Specialverzeichniss der in der Schweiz beobachteten. pp. 1-228, pls I-XVII. Bern: Verlag von Jent & Reinert.
Taxonomic status: currently recognized as a distinct genus.
Description: Unicellular,biflagellate and uninucleate algae with protoplasts contained in a firm,strongly compressed, colorless to brownish lorica; color resulting from iron deposition.In narrow side view, lorica obviously consists of two equal sections withclosely adpressed contact margins, sometimes slightly raised forming anindistinct keel. Lorica surface smooth, slightly roughened or variouslyornamented. In broad front view, lorica ovoid, ellipsoid, globose orbroadly and irregularly undulate. Protoplast somewhat smaller thanlorica. Chloroplast parietal, cup-shaped, with an anterior stigma, withor without a pyrenoid. Flagella anterior, emerging from a common openingin lorica or from separate openings. Two contractile vacuoles present atbase of flagella.Asexualreproduction by division into 2- 4-8(-16) daughter cells. Daughter cellsreleased on separation of two halves of mother cell lorica. Sexual reproductionapparently occurs by fusion of isogametes, giving rise to quadriflagellateplanozygote; mature zygote with thickened wall. Meiosis presumably zygotic.
Comments: Phacotus cosmopolitan with twelve well described species; allinfrequently encountered freshwater forms, in many cases known only fromtype localities. Four additional species of doubtful taxonomic validitywere described by Playfair (1918, P. bullatus) and Skvortzow (1957, P.asiaticus, P. hyalina, P. oblongus). P. bullatusmay not be properly assigned to Phacotus (Ettl 1983a; Huber-Pestalozzi1961), whereas the Skvortzow taxa are poorly described.InPhacotus lenticularis (Ehrenberg)Stein, the normally copious mucilageenvelope is greatly reduced in thickness in cells grown in nitrogen-supplementedmedium. Depending upon nitrogen source, the structure and composition ofthe lorica varies. Ultrastructurally, visualization of lorica andmucilage is enhanced by staining with alcian blue, thus corroborating chemicalevidence of a high anionic charge density. By weight, the lorica was 36 %carbohydrate (glucose the principal sugar); 26 % protein; 4 % sulfate; andvarious minerals, mainly calcium and manganese, comprising the remainder.The extracellular mucilage is a glycoprotein, with hydroxyproline as principal amino acid. Loricas subjected to protease and trypsin digestion undergostructural alteration
NCBI Nucleotide Sequences
Numbers of names and species: There are 24 species (and infraspecific) names in the database at present, of which 13 have 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):
Phacotus angulosus (H.J.Carter) F.Stein C
Phacotus angustus Pascher C
Phacotus asiaticus Skvortzov P
Phacotus australis Playfair C
Phacotus bullatus Playfair C
Phacotus bullatus var. conicus Playfair C
Phacotus coccifer Korshikov C
Phacotus crassus Playfair C
Phacotus glaber Playfair C
Phacotus lendneri Chodat C
Phacotus lenticularis var. sphaericus sphaerica S.Wislouch P
Phacotus lenticularis var. undulata R.Shyam & Y.S.R.K.Sarma P
Phacotus lenticularis var. sphaericus Wislouch P
Phacotus lenticularis f. cordata T.Hortobágyi P
Phacotus lenticularis (Ehrenberg) Deising C
Phacotus minusculus Bourrelly C
Phacotus oblongus Skvortzov P
Phacotus pallidus Korshikov C
Phacotus perforata B.V.Skvortov P
Phacotus rectangularis Playfair C
Phacotus reticulatus Playfair C
Phacotus sphaericus (Wislouch) B.Giering P
Phacotus subglobosus A.A.Pascher P
Phacotus viridis Perty S - type
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=43459
Cite this record as:
Michael Guiry in Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 11 December 2013.
Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:6932