Fig. 2. SEM. Periflagellar area: a narrow V-shaped depression on right valve. Narrow periflagellar collar wraps around flagellar and auxiliary pores (arrowheads). Longitudinal flagellum present (arrow). Left anterior margin with a thickened, curved and flattened apical collar that borders periflagellar area. A=auxiliary pore; F=flagellar pore.
Fig. 3. SEM. Reticulae: a network of ridges with round to oval depressions. Within surface depressions are narrow kidney-shaped openings (arrows). Bacteria on cell surface (arrowheads).