Neidium affine(Ehr.) Pfitz.
Length:37

 Width:11

Striae:20

 Puncta:































Collection 1788

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Authority information

(Ehr.) Pfitzer, Bot. Abh. Geb. Morph. Physiol., 1(2):39. 1871 (Stoermer and Yang 1969).

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This image was taken utilizing DIC for the specimen above.


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This taxon is consticted centrally. It has a straight raphe valve and is slightly narrower towards the ends. The valve is linear-lanceolate and has rounded ends. The sides are parallel with a straight axial area. The central area is elliptical and the striae are parallel and/or oblique. They become convergent on the ends (Patrick and Reimer 1966).


  • Type Locality
    USA, Maryland, Montgomery County, Potomac River (Patrick and Reimer 1966).
  • Synonyms
    Navicula amphigomphus Ehr. in pl. 49, fig. 32. 1877 (Patrick and Reimer 1966).


  • Ecology
    This taxon may be found in lakes,rivers, springs, streams, ponds, pools and thermal springs. It preferens fresh water and is most common in quiet areas. It is not found in large numbers (Patrick and Reimer 1966; Beaver 1981 ) and is considered to be alkaliphilous to ph indifferent and oligohalobous (Lowe 1974 ). (Beaver 1981 ).

    Size ranges and morphology

  • Length is 30 to 65 micrometers (Patrick and Reimer 1966).
  • Width is 8 to 13 micrometers (Patrick and Reimer 1966).
  • Striae are 22 to 24 in 10 micrometers (Patrick and Reimer 1966).
  • Puncta are around 24 in 10 micrometers (Patrick and Reimer 1966).