157,571 species and infraspecific names are in the database, 22,210 images, 60,987 bibliographic items, 459,373 distributional records.

Leyanella G.R.Hasle, H.A.von Stosch & E.E.Syvertsen, 1983

Empire Eukaryota
Kingdom Chromista
Phylum Bacillariophyta
Subphylum Bacillariophytina
Class Mediophyceae
Subclass Cymatosirophycidae
Order Cymatosirales
Family Cymatosiraceae

Holotype species: Leyanella arenaria G.R.Hasle, H.A.von Stosch & E.E.Syvertsen

Original publication and holotype designation: Hasle, G.R., Stosch, H.A. von & Syvertsen, E.E. (1983). Cymatosiraceae, a new diatom family. Bacillaria 6: 9-156.

Taxonomic status: currently recognized as a distinct genus.

Most recent taxonomic treatment adopted: Nikolaev, V.A., Kociolek, J.P., Fourtanier, E., Barron, J.A. & Harwood, D.M. (2001). Late Cretaceous diatoms (Bacillariophyceae) from the Marca Shale member of the Moreno Formation, California. Occasional Papers of the California Academy of Sciences 152: [1]-119, 39 pls.

Description: Cells curved in girdle view. heterovalvar, attached to form long filaments; Hasle et al. (1983) also report solitary cells. One plate-like plastid. Marine, living amongst sand grains on coastal flats. One valve of each cell concave, the other convex, and bearing two long, hair-like projections (pili); narrowly lanceolate to elliptical (after prolonged growth in culture). Mantles shallow. Areolae forming a single row along the margin of the valve face; sometimes there are also a few scattered on the valve face itself. The areolae contain domed cribra at their external apertures. Ocelluli occur at either end on slight elevations of the valve and are inclined, facing outwards. The pili arise from near the ocelluli and the convex valve and each bears a reflexed branch near its base; they are slightly displaced from the apical axis, lying diagonally with respect to it. Beneath the tip of the reflexed branch the valve face has an area of small papillae. Along the junction between valve face and mantle there is a delicate upright membrane, which is porous and lace-like and lies along the marginal row of areolae. The lower perforations through the membrane are triangular and large; the upper ones are smaller and round, and contain fine porous plates. A small submarginal tubular process occurs at the centre of the concave valve. The cingulum consists of eight or more open copulae; the most abvalvar has a row of small teeth along its abvalvar edge.

The most recent alteration to this page was made on 9 Dec 2015 by M.D. Guiry.

Comments: This genus of the Cymatosiraceae resembles Arcocellulus in its possession of a membranous ridge along the edge of the valve dface but the valve structure is not the same and the pili occur on the convex valve in Leyonella but on the concave valve in Arcocellulus. For a more comprehensive description, see Hasle et al. (1983).

Numbers of names and species: There are 3 species names in the database at present, of which 3 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):

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Verification of data
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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 September 2003 by M.D. Guiry

Verified by: 09 December 2015 by M.D. Guiry

Linking to this page: http://www.algaebase.org/search/genus/detail/?genus_id=46637

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Please cite this record as:
M.D. Guiry in Guiry, M.D. & Guiry, G.M. 2020. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. http://www.algaebase.org; searched on 26 February 2020.

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