Fig. 2. SEM. Left valve: anterior end flat to slightly concave with raised apical ridge. Valve margins appear as a flagne around cell. Center of valve devoid of pores.
Fig. 3. SEM. Unevenly distributed kidney-shaped to circular or oblong valve pores.
Fig. 4. SEM. Distinct marginal ridge appears as a flange around the cell, with a row of equally spaced marginal pores.
Fig. 5. SEM. Periflagellar area: a broad triangle bordered by a thin apical ridge (raised margin) set in V-shaped depression on right valve. Flagellar and auxiliary pores nearly equal in size, each surrounded by curved and flared periflagellar collar. A=auxiliary pore; F=flagellar pore.
Fig. 6. SEM. Periflagellar area: protuberant periflagellar collar surrounds both pores.
Fig. 7. Line drawing. Valve poroid and marginal pore arrangement.
Fig. 8. LM. Valve poroid and marginal pore arrangement: Calcoflour White used.
Fig. 9. LM. Central pyrenoid and posterior nucleus. N=nucleus; P=pyrenoid.