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Sentusidinium eisenackii ssp. vermiculatum
Sentusidinium eisenackii ?subsp. vermiculatum (Boltenhagen, 1977, p.57–58, pl.5, figs.7a–b,8a–b) Lentin and Williams, 1981, p.253.
Holotype: Boltenhagen, 1977, pl.5, figs.7a–b; Fauconnier and Masure, 2004, pl.70, fig.6. Originally Tenua eisenackii var. vermiculata, subsequently Sentusidinium eisenackii subsp. vermiculatum, thirdly (and now) Sentusidinium eisenackii? subsp. vermiculatum. Questionable assignment: Courtinat in Fauconnier and Masure (2004, p.487) as a problematic taxon. Age: Cenomanian–Turonian.
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Original description: [Boltenhagen, 1977] (translated from French):
Tenua eisenackii nov. sp., var. vermiculata nov.
Makoc Series and Red Series, Turonian-Basal and Cenomanian; Libreville (Gabon, Equatorial Africa).
DESCRIPTION
Our specimens are similar in shape, archaeopyle, and general appearance to the type species. The difference lies only in the detail of the ornamentation.
The ornamental elements are very short, more or less cylindrical, filiform in appearance, and very tightly packed. At the apex, these elements widen and branch out in such a way that, through their intertwining, a discontinuous vault is formed, which can be observed in a meridian optical section. When projected onto the shell surface, the ornamentation thus results in a very dense vermiculated micronetwork.
OBSERVATION
This variety was found in the same layers as the type species. The state of conservation of the ornamentation of the different specimens does not always allow them to be attributed either to the type species or to the variety described.
DIMENSIONS
Holotype:
shell (with ornamentation): d' = 88 x 85 μ
shell (without ornamentation): d" = 84 x 80 μ
antapical cap: d"' = 84 x 68 μ
ornamental elements: L = 2 - 3 μ
Paratype:
antapical cap (with ornamentation): d' = 83 x 67 μ
antapical cap (without ornamentation): d'' = 80 x 63 μ
ornamental elements: L = ± 3 μ
Based on 5 other specimens:
shell (with ornamentation): d' = 88 x 84 μ to 73 x 68 μ
shell (without ornamentation): d" = 86 x 78 μ to 70 x 66 μ
ornamental elements: L = 2, 3, 4 μ
COMPARISON
In terms of the shape of the ornamentation elements, the described specimens resemble T. verrucosa SAR. 1968 (p. 232, PI. I, Fig. 17,3,6). It differs from the cited species by the absence of a cingulum and sulcus, by its twice-larger size, and by the vermiculated appearance of its ornamentation.
Stratigraphic and Geographic Position
Upper Cretaceous: Turonian-Cenomanian; Gabon (Libreville and North Ogooué).
Holotype: Boltenhagen, 1977, pl.5, figs.7a–b; Fauconnier and Masure, 2004, pl.70, fig.6. Originally Tenua eisenackii var. vermiculata, subsequently Sentusidinium eisenackii subsp. vermiculatum, thirdly (and now) Sentusidinium eisenackii? subsp. vermiculatum. Questionable assignment: Courtinat in Fauconnier and Masure (2004, p.487) as a problematic taxon. Age: Cenomanian–Turonian.
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Original description: [Boltenhagen, 1977] (translated from French):
Tenua eisenackii nov. sp., var. vermiculata nov.
Makoc Series and Red Series, Turonian-Basal and Cenomanian; Libreville (Gabon, Equatorial Africa).
DESCRIPTION
Our specimens are similar in shape, archaeopyle, and general appearance to the type species. The difference lies only in the detail of the ornamentation.
The ornamental elements are very short, more or less cylindrical, filiform in appearance, and very tightly packed. At the apex, these elements widen and branch out in such a way that, through their intertwining, a discontinuous vault is formed, which can be observed in a meridian optical section. When projected onto the shell surface, the ornamentation thus results in a very dense vermiculated micronetwork.
OBSERVATION
This variety was found in the same layers as the type species. The state of conservation of the ornamentation of the different specimens does not always allow them to be attributed either to the type species or to the variety described.
DIMENSIONS
Holotype:
shell (with ornamentation): d' = 88 x 85 μ
shell (without ornamentation): d" = 84 x 80 μ
antapical cap: d"' = 84 x 68 μ
ornamental elements: L = 2 - 3 μ
Paratype:
antapical cap (with ornamentation): d' = 83 x 67 μ
antapical cap (without ornamentation): d'' = 80 x 63 μ
ornamental elements: L = ± 3 μ
Based on 5 other specimens:
shell (with ornamentation): d' = 88 x 84 μ to 73 x 68 μ
shell (without ornamentation): d" = 86 x 78 μ to 70 x 66 μ
ornamental elements: L = 2, 3, 4 μ
COMPARISON
In terms of the shape of the ornamentation elements, the described specimens resemble T. verrucosa SAR. 1968 (p. 232, PI. I, Fig. 17,3,6). It differs from the cited species by the absence of a cingulum and sulcus, by its twice-larger size, and by the vermiculated appearance of its ornamentation.
Stratigraphic and Geographic Position
Upper Cretaceous: Turonian-Cenomanian; Gabon (Libreville and North Ogooué).