Rivularia C.Agardh ex Bornet & Flahault, 1886: 345

Classification:
Empire Prokaryota
Kingdom Bacteria
Subkingdom Negibacteria
Phylum Cyanobacteria
Class Cyanophyceae
Subclass Nostocophycideae
Order Nostocales
Family Rivulariaceae

Lectotype species: Rivularia dura Roth ex Bornet & Flahault

Original publication:Bornet, É. & Flahault, C. (1886). Revision des Nostocacées hétérocystées contenues dans les principaux herbiers de France. Annales des Sciences Naturelles, Botanique, Septième série 3: 323-381.
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Type designated inGeitler, L. (1942). Schizophyta: Klasse Schizophyceae. In: Die natürlichen Pflanzenfamilien, Sweite Auflage. (Engler, A. & Prantl, K. Eds) Vol.1b, pp. 1-232. Leipzig: Wilhelm Engelmann.

Taxonomic status: currently recognized as a distinct genus.

Description: Filamentous; filaments heteropolar, differentiated into basal and apical parts, simple, joined parallel into firm, at the beginning of the vegetation cycle hemispherical or spherical, later sometimes vast, flat, macroscopic, irregular strata, to several cm or dm in diam. and several mm thick; strata layered (sometimes with several layers), with densely agglomerated trichomes, oriented by their bases with heterocytes to the substrate and by the apical hair-like parts to the surface of the colony. Strata gelatinous to leathery or intensely incrusted by calcium carbonate, always covering the substrate. Trichomes more or less cylindrical, constricted or unconstricted at the cross walls, dividing at intercalary heterocytes: the divided trichomes separate from one another, but remain parallel located within the mother sheaths in the colony. Hairs composed of narrow, long, hyaline cells. Sheaths firm, sometimes lamellated, colorless or yellow-brown, enveloping all the "daughter" trichomes, which produce their own sheaths. Aerotopes and akinetes lacking. Cell division perpendicular to the long axis of a trichome, later in meristematic zones. Reproduction by dissociation of trichomes within colonies and heterocytes and by hormogonia, separating after the separation of the hair by the help of necridic cells and sometimes liberating from the colonies. Only periphytic species, often on calcareous substrates (and then intensely incrusted by calcium carbonate), but exist also epilithic and epiphytic, not encrusted species. Important members of travertine-forming biocenoses. Several species known from marine littoral; in fresh waters, they prefer clear, unpolluted, streaming or stagnant waters.

Numbers of names and species: There are 94 species (and infraspecific) names in the database at present, of which 41 have been flagged as currently accepted taxonomically.

Names: ('C' indicates a name that is currently 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):

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: http://www.algaebase.org/search/genus/detail/?genus_id=42977

Citing AlgaeBase
Cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2013. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 20 June 2013.

Algaebase taxon LSID: urn:lsid:algaebase.org:taxname:7318