Frustulia inculta has parallel striae at the apices. In addition, the central nodule of F. amphipleuroides is generally much more elongate than that of F. inculta. Frustulia quadrisinuata has noticeably undulate margins.
LM scalebar = 10 µm
Length Range
63.0-97.0 µm
Width Range
15.0-16.5 µm
Striae in 10 µm
23-25 in the center, 25-26 at the ends