Hyalotheca Ehrenberg ex Ralfs, 1848
Lectotype species: Hyalotheca mucosa Ralfs
Original publication: Ralfs, J. (1848). The British Desmidieae The drawings by Edward Jenner, A.L.S. pp. [i]-xxii, [i], [1]-226, 35 pls. London: Reeve, Benham & Reeve, King William Street, Strand.
Request PDFType designated in: Guiry, M.D. (2013). Taxonomy and nomenclature of the Conjugatophyceae (=Zygnematophyceae). Algae. An International Journal of Algal Research 28: 1-29.
Description: Cells more or less cylindrical, united at broadly truncate ends into long filaments, with or without slight median constriction (isthmus) where semicell walls overlap. Some species with small protuberances near cell median, best seen in end view (two on opposite sides or three equally spaced around cell). Cell wall smooth with pores arranged in transverse rows. Narrow or broad gelatinous sheath present. Chloroplasts 2 per cell per cell, axial, stellate in end view, with central pyrenoid. Nucleus in middle between chloroplasts. Asexual reproduction usually by cell division and new semicell formation typical of Cosmarium-type desmids (see Cosmarium) but daughte cells remain attached by part of primary wall. Aplanospores known in two species; filament usually dissociate, cytoplasm rounds up and thick wall forms. Sexual reproduction by conjugation known in three species. Filaments come together; cells dissociate before gametangia pair. Gametes fuse in broad conjugation tube. Zygospore spherical, unornamented; usually remains surrounded by conjugation tube and gametangial semicell walls. Hyalotheca dissiliens and H. mucosa cosmopolitan; usually in acidic, oligotrophic lakes, ponds, swamps and streams.
Information contributed by: J.F. Gerrath. The most recent alteration to this page was made on 2013-09-12 by M.D. Guiry.
Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Guiry, M.D. (2013). Taxonomy and nomenclature of the Conjugatophyceae (=Zygnematophyceae). Algae. An International Journal of Algal Research 28: 1-29.
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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera,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.
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Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 12 September 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 23 November 2024
