Paraphysomonas De Saedeleer, 1930
Holotype species: Paraphysomonas vestita (A.Stokes) De Saedeleer
Original publication and holotype designation: De Saedeleer, H. (1929). Notules systématiques. VI. Physomonas. Annales de Protistologie 2: 177-178.
Description: Cells colorless, solitary, spherical to slightly ovate or elongate in shape, covered with siliceous scales or spines and at the anterior end bearing 2 flagella of unequal length. Species of Paraphysomonas are usually found as freely swimming cells, but they also occur attached to bacterial mats or other surfaces, occasionally forming a stalk at the posterior end of the cell. Except for the presence of scales, cells closely resemble cells of Spumella. The long flagellum has tripartite tubular hairs, the short flagellum is smooth and in most species examined has no flagellar swelling (exception - P. caelifrica). A leucoplast exists in all species examined, but it usually occupies an internal position in the cell and a stigma is lacking (except for P. caelifrica). Scales and spines of most species are visible with an electron microscope only and are variously patterned, sometimes broken up into an open meshwork structure. In many species there is only one scale or spine type per cell, but species with 2 or 3 different types also occur. Scales and spines are developed within flat vesicles which are intimately associated with cisternae of rough endoplasmic reticulum in the peripheral cytoplasm. Protoplast also containing 1-2 contractile vacuoles, food vacuoles and vacuoles with a storage product (probably chrysolaminaran). Cells can ingest food particles (e. g. bacteria, diatoms, small chlorococcalean algae) in large quantities. The flagellar pit area has apparently no adhering scales, and this may facilitate food uptake. Prey is incorporated in food vacuoles within a few seconds; bulky prey may cause cell distortion. Undigested particles are extruded near the posterior end of the cell. Reproduction by binary fission into equal daughter cells. Stomatocysts observed in some species. Most species from freshwater, 11 species from marine habitats. P. vestita and P. imperforata are especially widely distributed and common both in freshwater and marine plankton.
Information contributed by: H.R. Preisig. The most recent alteration to this page was made on 2021-10-11 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Gender: This genus name is currently treated as feminine.
Most recent taxonomic treatment adopted: Kristiansen, J. & Preisig, H.R. (2001). Encyclopedia of Chrysophyte genera. Bibliotheca Phycologica 110: 1-260.
Comments: According to Bérard-Therriault (1999; 319) the order for this genera is Chrysomonadida and the family is Paraphysomonadaceae. Throndsen (1997: 620) record this genus as being a member of the Order Ochromonadales.
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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.
Linking to this page: https://www.algaebase.org/search/genus/detail/?genus_id=43805
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 11 October 2021. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 23 November 2024
