Pinnularia tenuis Greg.
Length:17

 Width:4.5

 Striae:20






























Collection 1781a

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Pinnularia tennis Gregory 1854(Krammer, K. and Lange-Bertalot, H. 1986).

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This image was taken with an additional 40% magnification.



This image was taken with the additional magnification and utilizing DIC.


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This description is from Krammer's Caloneis tenuis, which he has as a synonym to P. tenuis. Valve linear to valve-elliptica. Sides parallel to triundulate sides. Ends are slightly distinguishable, bluntly rounded, and slightly capitate. Raphe weakly bent; raphe axis in middle somewhat lateral to philiform, bent at ends. Central nodule is indistinct. End pole nodules are distinctly visible, they are large and bayonet shaped. Axial area is variable, from very thin, linear to very broad, lanceolate-like. Central area variable, from small, circular to large rectangular. Commonly asymmetrical fascia. Striae in the middle are parallel to weakly radial, at the poles are parallel to lightly convergent (Krammer, K. and Lange-Bertalot, H. 1986).


  • Synonyms
    Caloneis tenuis Krammer 1985; Pinnularia gracillima Gregory 1856 (Krammer, K. and Lange-Bertalot, H. 1986).

  • Ecology
    Cosmopolitan, especially in the northern alpine areas. Found in standing or flowing water. Oligotrophic water with low to moderate electrolyte content(Krammer, K. and Lange-Bertalot, H. 1986; Beaver 1981).

    Size ranges and morphology

  • Length is 20 to 50 micrometers (Krammer, K. and Lange-Bertalot, H. 1986).
  • Width is 4 to 7 micrometers (Krammer, K. and Lange-Bertalot, H. 1986).
  • Striae are 16 to 24 in 10 micrometers (Krammer, K. and Lange-Bertalot, H. 1986).