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Dinogymnium strombomorphum
From Fensome et al., 2019:
Dinogymnium strombomorphum (Deflandre, 1943, p.501, pl.17, figs.4–6; text-figs.5–7) Evitt et al., 1967, p.23. Holotype: Deflandre, 1943, pl.17, figs.4–6; text-figs.5–7. Originally Gymnodinium (Appendix B), subsequently (and now) Dinogymnium. Age: ?Senonian.
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Original description, Deflandre 1943: Gymnodinium strombomorphum (Fig. 5 à 7 et Pl. XVII, fig. 4 à 6)
Holotype; AR 35. Silex (Senonien) S. 440, Saint-Leu-la-Fûret (S. et O.).
The structure of the base of the hypotheca, which gives this species the appearance of a top, earned it its specific name. The right lateral view, in which the only type is still presented, is very characteristic. The transverse groove, wide and deep, is quite strongly helical; the longitudinal groove is very easily perceptible by the play of the focus, which allows to realize its extension, marked especially on the epitheca. The frontal view (fig. 7) was reconstructed by the same means, which however leaves a doubt on the termination of the apex, perhaps a little less conical than it appears in figure 7.
In lateral view, the epitheca is conical, and its cross-section roughly represents an equilateral triangle. The hypotheca is cup-shaped, with the antapex ending in a small conical knob. The membrane is transparent, slightly brownish, and indistinctly marked with small punctations.
The dimensions are as follows: length 21 µm; width in lateral view 14 µm; in frontal view, approximately 16 to 17 µm; width of the transverse groove approximately 5 µm.
Quite close, morphologically, to the preceding species, Gymnodinium strombomorphum, like it, resembles no extant Gymnodinium.
Dinogymnium strombomorphum (Deflandre, 1943, p.501, pl.17, figs.4–6; text-figs.5–7) Evitt et al., 1967, p.23. Holotype: Deflandre, 1943, pl.17, figs.4–6; text-figs.5–7. Originally Gymnodinium (Appendix B), subsequently (and now) Dinogymnium. Age: ?Senonian.
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Original description, Deflandre 1943: Gymnodinium strombomorphum (Fig. 5 à 7 et Pl. XVII, fig. 4 à 6)
Holotype; AR 35. Silex (Senonien) S. 440, Saint-Leu-la-Fûret (S. et O.).
The structure of the base of the hypotheca, which gives this species the appearance of a top, earned it its specific name. The right lateral view, in which the only type is still presented, is very characteristic. The transverse groove, wide and deep, is quite strongly helical; the longitudinal groove is very easily perceptible by the play of the focus, which allows to realize its extension, marked especially on the epitheca. The frontal view (fig. 7) was reconstructed by the same means, which however leaves a doubt on the termination of the apex, perhaps a little less conical than it appears in figure 7.
In lateral view, the epitheca is conical, and its cross-section roughly represents an equilateral triangle. The hypotheca is cup-shaped, with the antapex ending in a small conical knob. The membrane is transparent, slightly brownish, and indistinctly marked with small punctations.
The dimensions are as follows: length 21 µm; width in lateral view 14 µm; in frontal view, approximately 16 to 17 µm; width of the transverse groove approximately 5 µm.
Quite close, morphologically, to the preceding species, Gymnodinium strombomorphum, like it, resembles no extant Gymnodinium.