H.A.Thomsen, in Thomsen & Boonruang (1984: 170, figs 14–17, 19–22)
Thomsen et al. (1990: 371, figs 13–16, 20, 21)
Cells solitary. Lorica barrel-shaped, to 31 µm long and 22 µm diameter. Longitudinal costae 8; transverse costae 3. The 2 anteriormost transverse costae of equivalent diameter, each comprising 8 costal strips; the third transverse costa much narrower, comprising 3 or 4 costal strips. All costal strips are narrow rods. Protoplast obovoid, to 7.5 µm long, situated in posterior end of the lorica.
Cells have been found only during the winter months in coastal Prydz Bay, East Antarctica (Marchant & Perrin, 1990); Weddell Sea in autumn months (Buck & Garrison, 1983).
Thomsen & Boonruang (1984) and Thomsen et al. (1990) documented a number of morphological forms of this species. In Antarctic samples we have observed Thomsen and Boonruang’s “form A” (Fig. 13.3c) and “form B” (not illustrated).