Sphaerozosma Corda ex Ralfs, 1848, nom. cons.

Holotype species: Sphaerozosma vertebratum Brébisson ex Ralfs

Original publication and holotype designation: 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.

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Description: Cells united in short or long filaments, small, compressed (biradiate), with deep median constriction (isthmus). Each semicell apex with pair of obliquely disposed, rod-like processes serving as anchor points for pieces of primary wall holding cells together in a filament. Apical processes arising close together or widely separated. Species with widely separated processes considered by some authors as Onychonema. Cell walls with pores often arranged in horizontal or oblique lines. One chloroplast per semicell, with central pyrenoid. Nucleus in isthmus. Asexual reproduction by cell division and new semicell morphogenesis typical of Cosmarium-type desmids. Apical processes initiated soon after cytokinesis. After full expansion of new semicells and secondary wall formation, primary wall shed from all but apical region, where it remains around and between apical processes to maintain both daughter cells in the filament. Sexual reproduction by conjugation of cells from disintegrated filaments. Zygotes form between gametangia; mature zygospores spherical, smooth-walled, or with several long acute spines or mamillate protuberances. Sphaerozosma with several cosmopolitan species usually in acidic, oligotrophic lacustrine environments.

Information contributed by: J.F. Gerrath. The most recent alteration to this page was made on 2015-10-19 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 neuter.

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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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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in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=43543

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 19 October 2015. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 22 November 2024