Back
Dinogymnium marthae
From Fensome et al., 2019:
Dinogymnium marthae (Deflandre, 1943, p.500, pl.17, fig.1; text-figs.1–4) Evitt et al., 1967, p.21. Holotype: Deflandre, 1943, pl.17, fig.1; text-figs.1–4. Originally Gymnodinium (Appendix B), subsequently (and now) Dinogymnium. Age: Senonian.
---------------------------------------------------------------------------------------------------
Original description, Deflandre, 1943: Gymnodinium marthae n.sp. (Fig. 1 à 4 et Pl. XVII, fig. 1) translation PKB 2025
Holotype : AR 42 (Silex ( ? Senonien) S. 156, Vanves, Seine
This pretty little species has a very distinctive silhouette, due to a marked disproportion between the size of the epitheca and that of the hypotheca. The unique type is represented by a right lateral view relative to the ventral surface. The focus allows the ventral view to be restored with a very sufficient approximation (Fig. 3), although we cannot be certain of the exact shape of the apex, which could be somewhat rounded.
The relatively wide transverse sillum is helical. The epitheca is conical and ends in a blunt point. The hypotheca, very broadly conical, appears slightly truncated at its tip when observed at very high magnification (Fig. 4). The hyaline membrane is very finely and irregularly punctuated, a characteristic likely related to preservation.
The dimensions are: length 135 µm; Width in side view 9 µm, in front view about 11 to 12 µm very approximate measurement made with the micrometer screw.
Gymnodinium marthae is not comparable to any of the plankton species of the present-day seas. The relative smallness of its hypotheca could suggest a connection with the genus Massartia Conrad, characterized by an epitheca at least three times larger than that of the hypotheca. Here, however, this proportion is a little lower. Gymnodinium marthae, currently the smallest fossil species, comes from a flint nodule, probably Senonian, collected in Vanves (Seine), particularly rich in microfossils.
Dinogymnium marthae (Deflandre, 1943, p.500, pl.17, fig.1; text-figs.1–4) Evitt et al., 1967, p.21. Holotype: Deflandre, 1943, pl.17, fig.1; text-figs.1–4. Originally Gymnodinium (Appendix B), subsequently (and now) Dinogymnium. Age: Senonian.
---------------------------------------------------------------------------------------------------
Original description, Deflandre, 1943: Gymnodinium marthae n.sp. (Fig. 1 à 4 et Pl. XVII, fig. 1) translation PKB 2025
Holotype : AR 42 (Silex ( ? Senonien) S. 156, Vanves, Seine
This pretty little species has a very distinctive silhouette, due to a marked disproportion between the size of the epitheca and that of the hypotheca. The unique type is represented by a right lateral view relative to the ventral surface. The focus allows the ventral view to be restored with a very sufficient approximation (Fig. 3), although we cannot be certain of the exact shape of the apex, which could be somewhat rounded.
The relatively wide transverse sillum is helical. The epitheca is conical and ends in a blunt point. The hypotheca, very broadly conical, appears slightly truncated at its tip when observed at very high magnification (Fig. 4). The hyaline membrane is very finely and irregularly punctuated, a characteristic likely related to preservation.
The dimensions are: length 135 µm; Width in side view 9 µm, in front view about 11 to 12 µm very approximate measurement made with the micrometer screw.
Gymnodinium marthae is not comparable to any of the plankton species of the present-day seas. The relative smallness of its hypotheca could suggest a connection with the genus Massartia Conrad, characterized by an epitheca at least three times larger than that of the hypotheca. Here, however, this proportion is a little lower. Gymnodinium marthae, currently the smallest fossil species, comes from a flint nodule, probably Senonian, collected in Vanves (Seine), particularly rich in microfossils.