Gymnodinium westralium Cookson and Eisenack, 1958, p.25, pl.1, fig.9. Emendation: May, 1977, p.118, as Dinogymnium westralium.

Now Dinogymnium. Originally Gymnodinium, subsequently (and now) Dinogymnium.

Holotype: Cookson and Eisenack, 1958, pl.1, fig.9
Locus typicus: Molecap Greensand, Gingin, W Australia
Stratum typicum: Senonian

Original description: Cookson and Eisenack, 1958, p. 25
Shell biconical, epitheca and hypotheca approximately the same size, the hypotheca being the more ounded of the two, seperated by a narrow and apparently shallow transvere furrow; a longitudinal furrow is not apparent.
The shell membrane is ornamented with numerous longitudinal ridges that converge from the furrow to the apex and antapex respectively. In the specimens from the Gearle Siltstone the membrane between the ridges is smooth, in those from the Korojon Calcite it has been regulary and longitudinally punctate. However, more examples will be needed to determine wether this feature is of primary or secondary origin.
Dimensions: Type 47x28 µm, other specimens 38x25 µm and 71x38 µm. Examples from from Molecap Greensand 58-61x48-54 µm.

Affinities:
Cookson and Eisenack, 1958, p. 26: In shape, G. westralium resembles G. cretaceum Defl. from the French Upper Cretaceous (Senonian), but differs from this species in its larger size and narrower furrow.