Pinnularia viridis v. commutata(Grun.) Cl.
Length:55

 Width:11

 Striae:11






























Collection 1788

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Pinnularia viridis var. commutata (Grun in V. H.) Cl., K. Svenska Vet.-Akad. Handl., Ny Foljd, 27(3):91. 1895(Patrick and Reimer 1966).

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This image was taken utilizing DIC for the specimen above.


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Valve linear, narrowing toward rounded ends. Axial area narrow, one-fourth to one-fifth breadth of the valve. Central area variable; small, somewhat elliptical, and usually asymmetrical; or widened unilaterally or bilaterally into a transverse fascia. Raphe complex; terminal fissures small but distinct. Striae slightly parallel throughout most of the valve, almost parallel at the center and parallel to slightly convergent toward the ends; crossed by a band which varies in distinctness. This taxon is distinguished from the nominate variety by its finer striae and central area of variable shape(Patrick and Reimer 1966).


  • Type Locality
    Uncertain (Patrick and Reimer 1966).

  • Synonyms
    Navicula virdis var. commutata Grun. in V. H., Syn. Diat. Belgique, pl. 5, fig. 6. 1880(Patrick and Reimer 1966).
    Pinnularia virdis var. fallax Cl., K. Svenska Vet.-Akad. Handl., Ny Froljd, 27(3):91. 1895(Patrick and Reimer 1966).
    Navicula virdis var. fallax (Cl.) Hust., Sussw.-Diat. Deutschlands, p. 47. 1909(Patrick and Reimer 1966).

  • Ecology
    This taxon seems to prefer cool water of low mineral content(Patrick and Reimer 1966). It has been found in generally alkalibiontic waters in lakes, estuaries, and terrestrial habitats(Beaver 1981).

    Size ranges and morphology

  • Length is 45 to 110 micrometers (Patrick and Reimer 1966).
  • Width is 9 to 20 micrometers (Patrick and Reimer 1966).
  • Striae are 9 to 12 in 10 micrometers (Patrick and Reimer 1966). 1966).