153,631 species and infraspecific names are in the database, 20,983 images, 59,437 bibliographic items, 412,634 distributional records.

Petalonema M.J.Berkeley ex C.Correns, 1898

Classification:
Empire Prokaryota
Kingdom Eubacteria
Subkingdom Negibacteria
Phylum Cyanobacteria
Class Cyanophyceae
Subclass Nostocophycidae
Order Nostocales
Family Scytonemataceae

Holotype species: Petalonema alatum (Borzì ex Bornet & Flahault) Correns

Original publication and holotype designation: Correns, C. (1889). Ueber Dickenwachsthum durch Intussusception bei einigen Algenmembranen. Flora (Jena) 72: 298-347, pl. XV.
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Taxonomic status: currently recognized as a distinct genus.

Most recent taxonomic treatment adopted: Komárek, J., Kastovsky, J., Mares, J. & Johansen, J.R. (2014). Taxonomic classification of cyanoprokaryotes (cyanobacterial genera) 2014, using a polyphasic approach. Preslia 86: 295-335.

Description: 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 3 Mar 2015 by M.D. Guiry.

Numbers of names and species: There are 9 species names in the database at present, as well as 3 infraspecific names. Of the species names, 9 have been flagged as accepted taxonomically on the basis of the listed literature under the species name. In some instances, opinions on taxonomic validity differ from author to author and users are encouraged to form their own opinion. AlgaeBase is a work in progress and should not be regarded as a definitive source only as a guide to the literature..

Names: ('C' indicates a name that is accepted taxonomically; 'S' a homotypic or heterotypic synonym; 'U' indicates a name of uncertain taxonomic status, but which has been subjected to some verification nomenclaturally; 'P' indicates a preliminary AlgaeBase entry that has not been subjected to any kind of verification. For more information on a species click on it to activate a link to the Species database):

Click here to also show infraspecific names in the list below.

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.

Created: 16 April 2003 by M.D. Guiry

Verified by: 03 March 2015 by M.D. Guiry

Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=45989

Citing AlgaeBase
Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2018. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 21 November 2018.

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