Spondylosium Brébisson ex Kützing, 1849
Lectotype species: Spondylosium depressum Brébisson
Original publication: Kützing, F.T. (1849). Species algarum. pp. [i]-vi, [1]-922. Lipsiae [Leipzig]: F.A. Brockhaus.
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 small or large, compressed (biradiate) or triradiate in end view, with deep median constriction (isthmus) where semicell walls overlap. Cell united into filaments by remains of primary wall between closely appressed secondary walls at apices of adjacent cells. Filaments commonly unattached but S. pulchellum sometimes attached by long gelatinous stalk.
Cell wall generally smooth with pores scattered or arranged in lines (small conical granules on lateral semicell margin in S. rectangulare). One chloroplast per semicell, with central mass and two flattened lateral lobes (visible in apical view only) on each side in biradiate cells, or into each angle of triradiate cells. Pyrenoid single and central, or several, in lateral lobes. Nucleus in isthmus.
Asexual reproduction by cell division and new semicell formation typical of Cosmarium-type desmids (see Cosmarium). Primary walls of new semicells persist at apex to maintain cells in filament. Possible aplanospores in single cells in field sample of S. nitens.
Sexual reproduction by conjugation between cells of disintegrated filaments in at least two species. Zygotes form between gametangia; mature zygospres spherical to irregular, smooth-walled or spinose.
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.
Comments: Spondylosium has several cosmopolitan species, and species usually occur in acidic, oligotrophic lakes and ponds.
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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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera,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=43545
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 22 November 2024
