From Fensome et al., 2019:
Dinogymnium denticulatum (Alberti, 1961, p.5, pl.3, figs.2–3) Evitt et al., 1967, p.18. Holotype: Alberti, 1961, pl.3, fig.2. Originally Gymnodinium (Appendix B), subsequently (and now) Dinogymnium. Herngreen (1975, p.63) implied that Dinogymnium undulosum is a possible taxonomic junior synonym of this species. Boltenhagen (1977, p.73) also proposed this combination. Age: Senonian.

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Original description: [Alberti, 1961] (translated from German):

Gymnodinium denticulatum n. sp.
Plate 3 Figs. 2 and 3

Holotype: The specimen preserved in specimen no. 33/2 Semo and shown in Plate 3 Fig. 2.
Typical locus: Semo bore (Brandenburg).
Typical stratum: Senon.
Diagnosis: Body double-conical, antapex blunt. Epitheca slightly larger than the hypotheca. Transverse furrow strongly depressed and broad. Longitudinal furrow sometimes on the hypotheca. Epitheca and hypotheca bear numerous finely undulating ribs covered with small teeth, which converge from the transverse furrow toward the two poles.
Notes: Alternation of ribs of different lengths, as in G. heterocostatum, was not observed. Whether the specimen shown in Fig. 3 belongs to this species is questionable, as the serrations of the ribs are only vaguely indicated.
Relationships: Distinguished from all other Gymnodinium species that exhibit ribs by the undulation and serration of these ribs.
Holotype dimensions: Length 55 μ, width 45 μ.
Material: 4 specimens.
Occurrence: Senon of the Semo bore.