Petalonema M.J.Berkeley ex Wolle, 1887
Holotype species: Petalonema alatum (Borzì ex Bornet & Flahault) Wolle
Original publication and holotype designation: Wolle, F. (1887). Fresh-Water Algæ of the United States; (exclusive of the Diatomaceæ) complemental to Desmids of the United States. Vol. 1-2 pp. 364, 157 plates. Bethlehem, Pennsylvania: Comenius Press.
Request PDFDescription: Filaments free, usually solitary or in small groups, slightly coiled, creeping on the substrate or a little erect, heteropolar, with morphologically separated base (sometimes with a heterocyte) and free apical end, with false branching (branches lateral , solitary or in pairs, dividing after the disintegration of trichomes at heterocytes). Sheaths firm, very thick, distinctly funnel-like lamellated, colorless or yellow-brown, limited from outside. Trichomes cylindrical in basal and middle parts, with elongated, cylindrical or barrel-shaped cells; terminal parts have cells shorter, barrel-shaped and usually widened; apical cells always rounded. Heterocytes intercalary, solitary, more or less spherical and usually wider than vegetative cells. Akinetes missing. Reproduction by hormogonia, separating from the apical parts of trichomes. Subaerophytic or submersed (freshwater), epilithic, on soil or epiphytic, several species are known from geographically limited areas (tropical species).
Information contributed by: J. Komárek. The most recent alteration to this page was made on 2023-03-06 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: Strunecký, O., Ivanova, A.P. & Mares, J. (2022 '2023'). An updated classification of cyanobacterial orders and families based on phylogenomic and polyphasic analysis (Review). Journal of Phycology 59(1): 12-51.
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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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera,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=45989
Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 06 March 2023. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 23 November 2024
