Guide to Punctastriata

Valves linear elliptic and may possess a central inflation. The striae are composed of a rectangular net of transapical and apical bars. Spines are present at the valve face/mantle junction on the costae, interrupting the striae, or both positions. The spines are variable in form. According to Williams and Round (1987) one apical porefield is present; according to Morales (2005) two apical porefields are present. The frustules are rectangular in girdle view, and often form chains linked by the spines.

This genus is difficult to identify in the light microscope, because the scanning electron microscope is required to observe the morphology of the striae. As a result, species within the genus are routinely misidentified. Punctastriata species are typically confused with Staurosirella pinnata. Although Punctastriata lancettula is commonly reported from North America, specimens have not been verified. That taxon is often confused with P. mimetica. All of these taxa require SEM for identification.