Penium Brébisson ex Ralfs, 1848
Lectotype species: Penium margaritaceum Brébisson ex 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 solitary, short-cylindric to elongate-cylindric (length 19-450 um; length 2-35 times width), straight, with broadly rounded or truncate ends; shallow median constriction sometimes present. Cell wall with or without girdle bands, smooth or with striae, pores, granules or spines. Ultrastructurally cell wall two layered, with perforated outer layer and continuous inner layer. Cell wall sometimes brown, often with different wall sections different shades of brown. Two (rarely four) chloroplasts per cell, axial and stellate in end view (spiralling parietal bands in one species) with 1-2 axial pyrenoids. Terminal vacuoles with small crystals in some species. Nucleus at middle between chloroplasts. Asexual reproduction by transverse cell division. Some species divide only at median suture and produce new semicell on each daughter cell. Other species from girdle band on new semicell. Sexual reproduction by conjugation. Gametangia come together within mucilage envelope;. gametes fuse between gametangial. Zygospores single or paired, spherical to ellipsoid (occasionally angular), usually smooth walled. Mesopore wall of P. silvae-nigrae corrugated or finely punctate. Penium cosmopolitan; usually in acidic, oligotrophic ponds or lakes or in Sphagnum bogs. Emend. Kouwets & Coesel 1984: 561.
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: Brook, A.J. & Johnson, L.R. (2002). Order Zygnematales. In: The Freshwater Algal Flora of the British Isles. An identification guide to freshwater and terrestrial algae. (John, D.M., Whitton, B.A. & Brook, A.J. Eds), pp. 479-593. Cambridge: Cambridge University Press.
Verification of Data
Users are responsible for verifying the accuracy of information before use, as noted on the website Content page.
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=43539
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 27 November 2024
