Parvicorbicula circularis Thomsen, 1976. Cell when dried approximately 3 x 5 microns The single flagellum, up to 15 microns long, protrudes above the lorica. The lorica is constructed of 4 longitudinal costae composed of 3 costal strips each and two transverse costae. One transverse costa (8 strips) delimits the lorica anteriorly. The bifurcated anterior tips of the longitudinal costae attach to the middle of every second transverse costal strip ( T -joints). The second transverse costa (6-8 strips) is located at the level of the joints between the first and the second longitudinal costal strip. In specimens with 8 costal strips in this costa, the longitudinal costae cross at every other joint between transverse costal strips. In specimens with 6-7 transverse costal strips, the crossings between longitudinal and transverse elements are less symmetric. The two posterior-most costal strips from each longitudinal costa overlap. The free ends of the penultimate longitudinal costal strips suspend a sheet which encompasses the cell.
