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Axiodinium sparnacium

Axiodinium sparnacium, Iakovleva, 2016, p. 4 (pl.1, figs.6,9–11; text-fig.4b (part))

Holotype: Iakovleva, 2016, pl.1, figs.10–11.
Paratype: Plate 1, figures 6, 9
Type stratum and locality: Sample 1-22, ∼7.0 m depth; Sinceny Member; BRGM Scientific Borehole Sinceny, Paris Basin, France.
Stratigraphical range: Earliest Eocene.
Age: earliest Eocene.

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Original description: [Iakovleva, 2016]:


Diagnosis:
A species of Axiodinium with a subrounded pericyst, having some weakly developed or no horns and bearing generally nontabular processes, although some reflect the tabulation.

Description:
A mid-size circumcavate cyst with subrounded outline.
Apical horn is at best weakly developed; lateral horns absent; antapical horns poorly developed, similar in size and shape to outgrowths on the lateral parts of the periphragm.
Periphragm ornamentation includes nontabular processes, which are distally free or bifid, some groups of which reflect the tabulation.
Endocyst subcircular.
Archaeopyle equiepeliform; operculum free.

Dimensions:
Holotype: pericyst length 79 µm; pericyst width 79 µm; endocyst length 59 µm; endocyst width 54 µm.
Paratype: pericyst length 79 µm; pericyst width 81 µm; endocyst length 59 µm; endocyst width 63 µm.
Dimensions of measured specimens: pericyst length 64–85 µm (mean value 76 µm); pericyst width 61–86 µm (mean value 76 µm); endocyst length 47–63 µm (mean value 57 µm); endocyst width 46–63 (mean value 56 µm). Eight specimens measured.

Affinities/Comparison:
This species differs from other species of Axiodinium by its smaller size and distinctive subrounded outline. With some processes partially reflecting the tabulation, Axiodinium sparnacium can be considered transitional to Vallodinium.
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