The taxonomy and ultrastructure of a marine dinoflagellate,<i>Scrippsiella minima</i>sp. nov.

Abstract

A new marine dinoflagellate, Scrippsiella minima sp. nov., is described from the Atlantic Ocean. It is tear-shaped, with a mean length of 20 μm and a mean width of 15 μm. The plate tabulation is po, x, 4′, 3a, 7″, 6c, 5s, 5‴ and 2″″. When it is induced to undergo sexual reproduction, resting cysts are formed which are ovoid in shape, about 34 μm long × 29 μm wide and have a thick organic wall covered with small calcareous verrucae. Ultrastructural observation shows that S. minima is of typical dinoflagellate organization. The pusule consists of a group of large vesicles connecting with a collecting chamber. The fibrous structures in the area of the apical pore and subthecal microtubular system have been examined and compared with those in other dinoflagellates. A comparison of the ultrastructure with other Scrippsiella species is also presented.