Eremosphaera De Bary, 1858
Holotype species: Eremosphaera viridis De Bary
Original publication and holotype designation: De Bary, A. (1858). Untersuchungen über die Familie der Conjugaten (Zygnemeen und Desmidieen) Ein Beitrag zur physiologischen und beschreibenden Botanik. pp. [i]-vi, 1-91. Leipzig: A. Förstnersche Buchhandlung (Arthur Felix).
Request PDFDescription: Thalli sometimes colonial in clusters of 2-4, mostly solitary with spherical to subspherical or ellipsoidal cells with or without conspicuous mucilaginous envelope. Cells 23-130 x 20-120 µm with cellulosic cell walls 0.5-1.0 µm thick; most species with polar thickenings; one species, E. oocystoides with numerous radial spicules. Cells with large central vacuole traversed by radial strands of cytoplasm which connect central nucleus to periphery. Cytoplasm often with numerous granules and oil droplets; calcium oxalate crystals in E<. viridis. Nuclei single and mostly central, 5-31 µm diameter, with up to five nucleoli; numerous chloroplasts parietal, discoid to elongate, occasionally radial in cytoplasmic strands; each chloroplast with 1-3 pyrenoids, often surrounded with starch grains. Asexual reproduction by autospores; 2-4 per sporangium and released by rupture of parental cell wall which often remains distinct in culture. Cytokinesis in E. viridis unusual in that plasmalemma formation associated with fusion of open membranes rather than vesicles. Open membranes may originate through bursting of heavily staining vesicles. Sexual reproduction oogamous and homothallic, known only in E. viridis. Eggs similar to autospores, producing fertilization papilla at maturity. Sperm biflagellate and spherical, without plastids or stigma, 16-64 per antheridium; produced by repeated bipartitions of protoplasts. After fertilization zygotes produce thickened walls. Chromosomes described only in E. viridis with n? = 80.
Information contributed by: D.J. Garbary & M.D. Guiry. The most recent alteration to this page was made on 2014-02-09 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Tsarenko, P.M. (2011). Trebouxiophyceae. In: Algae of Ukraine: diversity, nomenclature, taxonomy, ecology and geography. Volume 3: Chlorophyta. (Tsarenko, P.M., Wasser, S.P. & Nevo, E. Eds), pp. 61-108. Ruggell: A.R.A. Gantner Verlag K.-G..
Comments: Species planktonic or benthic, associated with both acidic and alkaline freshwater in ponds, lakes and rivers in cool to tropical climates; reported from North America, Cuba, Europe and Australia. E. antillara, E. oocystoides and possibly E. minor endemic to North America and/or Cuba. Extracellular mucilage with fibrillar and slimy components; high polyuronic acid formation associated with increased phosphorus in medium. Fibrils ca 7 nm diameter with occasional branching or fusions. The large cells of E. viridis have been widely used as a model system in physiological studies, especially involving carbon transport and potassium channels. Species distinguished based on cell size and shape, presence of wall spicules (one species) and details of chloroplast morphology. Requires revision.
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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=43432
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 09 February 2014. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 23 November 2024
