Frustulia maoriana is a diatom species characterized by elongated and linear valves, typically measuring 10-30 micrometers in length. The valves have a flat valve face with parallel margins and fine, parallel striae running longitudinally on the surface. Valve apices are broadly rounded, and the central area is usually open or inconspicuous. The valve surface is punctuated with small pores called areolae arranged in longitudinal rows. This species is commonly found in freshwater environments, where it contributes to diatom populations and ecological processes such as nutrient cycling.