Roperia Grunow ex Pelletan, 1889
Holotype species: Roperia tesselata (Roper) Grunow ex Pelletan
Original publication and holotype designation: Pelletan, J. (1889). Les Diatomées. Histoire naturelle, préparation, classification et description des principales espèces. Part II. Journal de Micrographie 1889: [i]-viii, [1]-364, pls 6-10, figs 266-463.
Request PDFDescription: Cells discoid, solitary. Plastids numerous, discoid. A small marine planktonic genus. Valves circular, with a flat valve face and distinct mantles. A large opening (pseudonodulus) occurs near the valve rim; it appears open in our preparations for the EM, but it is most likely occluded by a silica membrane or an organic wall in the live cell. Areolae loculate, arranged in slightly curved decussate rows. The loculi open externally via cribra which are almost flush with the outer surface of the valve; internally they have large round foramina. The areolae are circular on the valve face, becoming diamond-shaped or merely continuous areas of pores on the mantle. Rimoportulae occur in a ring around the mantle. Their external openings are slit-like, angled and occur in a ring at the junction of the valve face and mantle. At this point there is either a rim or a series of flaps above the rimoportula openings that are often angled in relation to the mantle edge; some valves seem to combine these two features. Internally the rimoportulae are stalked and may be tilted at an angle to the mantle margin. Girdle bands not investigated in detail but appear wide, split and ligulate.
The most recent alteration to this page was made on 2019-11-02 by Salvador Valenzuela Miranda.Taxonomic status: This name is of an entity that is currently accepted taxonomically.
Most recent taxonomic treatment adopted: Round, F.E., Crawford, R.M. & Mann, D.G. (1990). The diatoms biology and morphology of the genera. pp. [i-ix], 1-747. Cambridge: Cambridge University Press.
Comments: The genus is small: only R. tessellata is recorded commonly, most other records being mis-identifications of Eupodiscus (see VanLandingham, 1979 who reports only one other species, R. marginata). The combination of the pseudonodulus and the silica flaps around the edge of the valve face enable this taxon to be distinguished from Coscinodiscus. A pseudonodulus also occurs in Actinocyclus but that genus has bullulate valves and simple openings to the rimoportulae. The arrangement of the rimoportulae around the margin of the valve is in some ways reminiscent of some species of Azpeitia.
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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.
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Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.
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Citing AlgaeBase
Cite this record as:
Salvador Valenzuela Miranda in Guiry, M.D. & Guiry, G.M. 02 November 2019. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. https://www.algaebase.org; searched on 19 April 2024
