This taxon has an elliptical central area. The striae are transverse and diagonal and cross each other with an angle of 55 to 60 degrees. The valve is sigmoid and narrow-lanceolate. It tapers to rounded ends (Patrick and Reimer 1966).
Synonyms
Gyrosigma delicatulum (W. Sm.) Elmore, Univ. Nebraska Stud., 21(1-4):105, pl.13, figs 512-513. 1922 (Patrick and Reimer 1966).
Type Locality
New England States, Middle Atlantic States, Gulf Coast States, East Central States, West Central States, Plains States, Utah, Arizona, California (Patrick and Reimer 1966).
Ecology
This taxons prefers fresh water that is hard though it has been found in brackish water (Patrick and Reimer 1966).
Length is 130 to 280 micrometers (Patrick and Reimer 1966).
Width is 13 to 19 micrometers (Patrick and Reimer 1966).
Striae are 20 to 23 in 10 micrometers (Patrick and Reimer 1966).
This image was taken utilizing DIC for the specimen above.