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Trichodinium boltenhagenii
From Fensome et al., 2019:
Trichodinium boltenhagenii Masure in Fauconnier and Masure, 2004, p.116.
Emendation: Masure in Fauconnier and Masure, 2004, p.116–117, as Trichodinium boltenhagenii.
Holotype: Boltenhagen, 1977, pl.7, figs.1a–b; Fauconnier and Masure, 2004, pl.15, fig.6.
Originally Chytroeisphaeridia spinosa, subsequently Cleistosphaeridium? spinosum, thirdly Circulodinium spinosum, fourthly (and now) Trichodinium boltenhagenii.
Substutute name for Chytroeisphaeridia spinosa Boltenhagen, 1977, p.54–55, pl.7, figs.1a–b,2,3a–b,4a–b,5a–b, since the name Trichodinium spinosum is preoccupied.
Age: Cenomanian–Turonian.
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Original description: [Boltenhagen, 1977] (translated from French):
Chytroeisphaeridia spinosa nov. sp.
Makoc Series and Red Series, Turonian-base and Cenomanian; Libreville (Gabon, Equatorial Africa).
DIAGNOSIS
Subspherical, inframicroreticulate shell covered by spaced spines of various shapes. The apical archaeopyle is polygonal, with continuous margins.
DESCRIPTION
Whole specimens of this species have a subspherical shape. The shell membrane, slightly punctate at 320x magnification, appears finely inframicroreticulate at 800x magnification. The typical ornamentation of this membrane consists of small, rigid, conical or truncated spines, often pointed and curved, or blunt at the apex. Spines of this type generally broaden at their base, but subcylindrical baculi, flattened or slightly thickened at the apex, are also observed.
The distribution of the omentation elements is fairly regular and suggests a grid pattern. In some specimens and in some places, alignments are observed along folds. However, the examination of 14 different individuals did not reveal preferential directions for these alignments, which could have provided indications of the presence of a cingulum or a sulcus.
The apical archaeopyle was mainly observed on a few subhypothecal caps in meridional projection. Its outline is polygonal (pentagonal?, hexagonal?) or subpolygonal; its edges are joined and regular, without cracks at the corners. In specimens observed in equatorial projection, tears following a broken line roughly concentric with the outline would indicate an operculum about to detach. In one specimen in meridional projection, an operculum is also observed detaching from the archaeopyle.
DIMENSIONS
Holotype:
shell without ornamentation, in equatorial projection: d = 74 x 72 μ
spines: L = 2 - 3 μ
Paratypes:
3 subhypothecal caps in meridian projection, unornamented: d = 75 x 55 μ; 67 x 54 μ; 64 x 53 μ
1 shell in equatorial projection: d = 61 x 59 μ
spines: L = 1.5 - 3 μ
Based on 9 other specimens and following their state of preservation:
largest shell: d' = 75 x 68 μ
smallest shell: d" = 52 x 51 μ
spines: L = 1.5 - 3 μ
COMPARISON
The archaeopyle characteristics of the described species correspond to those of the generotype: Chytroeisphaeridia chytroeides SAR. 1963 (Pl. 3, Fig. 3), whose shell is smooth and unornamented. Compared to C. pococki SAR. 1968 (p. 230, Pl. 3, Fig. 9), whose membrane is granulated, our species is characterized by its echinulate ornamentation.
Stratigraphic and Geographic Position
Upper Cretaceous: Turonian-Cenomanian; Gabon (Libreville and North Ogooué).
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Emendation Masure in Fauconnier and Masure, 2004, p.116–117, as Trichodinium boltenhagenii (translated from French):
Amended diagnosis: Proximate dinoflagellate cyst with a subspherical central body and a circular ambitus, with a wall formed by a fibropunctate autophragm. The ornamentation consists of short, rigid, and curved conical spines. The gonyaulacoid paratabulation is indicated by the archaeopyle and paracingulum outlined by alignments of spines. The archaeopyle is precingulate of type P (only 3") and the operculum is free.
Trichodinium boltenhagenii Masure in Fauconnier and Masure, 2004, p.116.
Emendation: Masure in Fauconnier and Masure, 2004, p.116–117, as Trichodinium boltenhagenii.
Holotype: Boltenhagen, 1977, pl.7, figs.1a–b; Fauconnier and Masure, 2004, pl.15, fig.6.
Originally Chytroeisphaeridia spinosa, subsequently Cleistosphaeridium? spinosum, thirdly Circulodinium spinosum, fourthly (and now) Trichodinium boltenhagenii.
Substutute name for Chytroeisphaeridia spinosa Boltenhagen, 1977, p.54–55, pl.7, figs.1a–b,2,3a–b,4a–b,5a–b, since the name Trichodinium spinosum is preoccupied.
Age: Cenomanian–Turonian.
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Original description: [Boltenhagen, 1977] (translated from French):
Chytroeisphaeridia spinosa nov. sp.
Makoc Series and Red Series, Turonian-base and Cenomanian; Libreville (Gabon, Equatorial Africa).
DIAGNOSIS
Subspherical, inframicroreticulate shell covered by spaced spines of various shapes. The apical archaeopyle is polygonal, with continuous margins.
DESCRIPTION
Whole specimens of this species have a subspherical shape. The shell membrane, slightly punctate at 320x magnification, appears finely inframicroreticulate at 800x magnification. The typical ornamentation of this membrane consists of small, rigid, conical or truncated spines, often pointed and curved, or blunt at the apex. Spines of this type generally broaden at their base, but subcylindrical baculi, flattened or slightly thickened at the apex, are also observed.
The distribution of the omentation elements is fairly regular and suggests a grid pattern. In some specimens and in some places, alignments are observed along folds. However, the examination of 14 different individuals did not reveal preferential directions for these alignments, which could have provided indications of the presence of a cingulum or a sulcus.
The apical archaeopyle was mainly observed on a few subhypothecal caps in meridional projection. Its outline is polygonal (pentagonal?, hexagonal?) or subpolygonal; its edges are joined and regular, without cracks at the corners. In specimens observed in equatorial projection, tears following a broken line roughly concentric with the outline would indicate an operculum about to detach. In one specimen in meridional projection, an operculum is also observed detaching from the archaeopyle.
DIMENSIONS
Holotype:
shell without ornamentation, in equatorial projection: d = 74 x 72 μ
spines: L = 2 - 3 μ
Paratypes:
3 subhypothecal caps in meridian projection, unornamented: d = 75 x 55 μ; 67 x 54 μ; 64 x 53 μ
1 shell in equatorial projection: d = 61 x 59 μ
spines: L = 1.5 - 3 μ
Based on 9 other specimens and following their state of preservation:
largest shell: d' = 75 x 68 μ
smallest shell: d" = 52 x 51 μ
spines: L = 1.5 - 3 μ
COMPARISON
The archaeopyle characteristics of the described species correspond to those of the generotype: Chytroeisphaeridia chytroeides SAR. 1963 (Pl. 3, Fig. 3), whose shell is smooth and unornamented. Compared to C. pococki SAR. 1968 (p. 230, Pl. 3, Fig. 9), whose membrane is granulated, our species is characterized by its echinulate ornamentation.
Stratigraphic and Geographic Position
Upper Cretaceous: Turonian-Cenomanian; Gabon (Libreville and North Ogooué).
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Emendation Masure in Fauconnier and Masure, 2004, p.116–117, as Trichodinium boltenhagenii (translated from French):
Amended diagnosis: Proximate dinoflagellate cyst with a subspherical central body and a circular ambitus, with a wall formed by a fibropunctate autophragm. The ornamentation consists of short, rigid, and curved conical spines. The gonyaulacoid paratabulation is indicated by the archaeopyle and paracingulum outlined by alignments of spines. The archaeopyle is precingulate of type P (only 3") and the operculum is free.