Williams 1990      Category: Araphid
TYPE SPECIES: Distronella asterionelloides Williams




Image Credit: Eduardo Morales

CLASS: Fragilariophyceae
  ORDER: Fragilariales
    FAMILY: Fragilariaceae

  1. Valves elongated, with capitate ends
  2. Striae unevenly spaced
  3. Rimoportula single, often central within a stria near one pole

Frustules of Distrionella are elongated with capitate ends. Valves may be slightly asymmetrical to the transapical axis. Striae are unevenly spaced and become scattered and more irregular at the valve ends. Transapical ribs often evident. A central sternum is absent. Porefields, composed of simple porelli, are present at both valve ends. One rimoportula is present, and is usually positioned centrally within a stria near one pole.

Distrionella is distinguished from Diatoma by its more lightly silicified valves and weaker transapical ribs. It is considered to be closely related to Diatoma and Asterionella. Distrionella incognita is common in lakes and rivers of Montana and Idaho.

Cite This Page:
Spaulding, S., and Edlund, M. (2008). Distrionella. In Diatoms of the United States. Retrieved April 26, 2018, from http://westerndiatoms.colorado.edu/taxa/genus/Distrionella

Contributor: Sarah Spaulding | Mark Edlund - December 2008
Reviewer: Sam Rushforth - May 2010