Gymnodinium nelsonense (Cookson, 1956) Evitt et al., 1967

Originally Gymnodinium, subsequently (and now) Dinogymnium.
Tax. sr. synonym of Dinogymnium (originally Gymnodinium) hyalinum (Vozzhennikova, 1967) Lentin and Williams, 1973, according to Lentin and Vozzhennikova, 1990.
Holotype: Cookson, 1956, pl.1, fig.10; Lentin and Vozzhennikova, 1990, pl.2, fig.8
Paratypes: Cookson, 1965
Locus typicus: Nelson Bore, Victoria, Australia
Stratum typicum: Senonian

Original description: Cookson, 1965, p.183
The cell is roughly fusiform with a delicate, finely and faintly granular membrane; usually it is more or less longitudinally folded and at approximately half its length transversely crumpled, so that the nature and even the existence of a transverse girdle is difficult to determine; a slight waist-like narrowing (Plate 1, Fig. 8) delimits a broad "epitheca" with a bluntly rounded apex from a somewhat longer "hypotheca", which gradually narrows towards a rounded or truncate antapex; frequently a small oval opening seems to be present at this end of the cell (Plate 1, Fig. 10).
Dimensions (approximate on account of folding). Holotype: length 70 Ám, width 38 Ám. Paratypes, 120x39 Ám, 75x36 Ám.