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Apectodinium williereae
From Fensome et al., 2019:
Apectodinium? williereae, (Boltenhagen, 1977, p.42–43, pl.3, figs.3a–b,4–6) Lentin and Williams, 1981, p.14.
Holotype: Boltenhagen, 1977, pl.3, figs.3a–b.
Originally Polysphaeridium, subsequently (and now) Apectodinium?.
Questionable assignment: Lentin and Williams (1981, p.14).
Age: Paleocene.
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Original description: [Boltenhagen, 1977] (translated from French):
Polysphaeridium williereae nov. sp.
Ozouri Series, Paleocene, Port-Gentil (Gabon, Equatorial Africa)
DIAGNOSIS
Spherical or ovoid shell with numerous short tubular appendages, ending in a tuft or star-shaped crown of spinules. Apical archaeopyle.
DESCRIPTION
The subspherical or ovoid shell of our specimens is covered by fairly short appendages of the same length, ending in a tuft or crown of small spines. The tuft is composed of several tiny spines, joined at the base, thus forming a "brush." The crown is made up of a few (3, 4, or 5) of these filiform spines, located in a plane or directed upward or downward, which gives a "star-shaped" appearance to the ends of these appendages.
In addition, the tips of some appendages are sometimes simply acuminate. The total number of appendages is around 50. They are all tubular and are inserted by large conical bases onto a smooth or punctuated periphragm. At 800x magnification, this punctuation actually corresponds to fine granulation, also visible on the appendages.
The smooth endophragm isolates the appendages from the interior of the shell. The total thickness of the membrane is approximately 1µ.
At first glance, the archaeopyle is not obvious. However, the more or less zigzagging edges of the observed caps suggest that these are not accidental tears. To verify the position of the presumed archaeopyle, we measured the axes of 10 caps. These measurements made it possible to establish the ratio of the minor axis to the major axis: it is between 0.72 and 0.91 (arithmetic mean: 0.8) and would indicate that this is an apical archaeopyle.
OBSERVATIONS
This species is almost exclusively found in the preparation studied, but whole specimens are rather rare.
DIMENSIONS
Holotype: shell (with appendages): d' = 92 x 84 μ
shell (without appendages): d'' = 75 x 72 μ
appendages L = 11-14 μ
average thickness = 1-1.5 μ
crown of spines: d = 3-4 μ
Paratypes:
1) cap (without appendages): d = 67-55 μ
appendages L = 12-16 μ
2) shell (with appendages): d' = 82-75 μ
(without appendages): d'' = 60-57 μ
appendages: L = 14-18 μ
Based on 18 other specimens:
shell (major axis) = 58-80 μ
(minor axis) = 52-72 μ
appendages: L = 11-18 μ
COMPARISON
The specimens described bear resemblance to Hystrichosphaeridium microtriaina KLUMPP 1953 (p. 390, PI. 17, Figs. 6 and 7) in the appearance of the appendage tips; however, the latter differ in the detail of the shape and the number of terminal spines. Furthermore, the amendment by A. EISENACK 1963 (p. 263) places the considered species of E. KLUMPP in the genus Cordosphaeridium, characterized by the fibrousness of the membrane, which is not the case for the Gabonese species.
Stratigraphic and Geographic Position
Tertiary: Paleocene; Gabon (Port-Gentil and Fernan-Vaz).
Apectodinium? williereae, (Boltenhagen, 1977, p.42–43, pl.3, figs.3a–b,4–6) Lentin and Williams, 1981, p.14.
Holotype: Boltenhagen, 1977, pl.3, figs.3a–b.
Originally Polysphaeridium, subsequently (and now) Apectodinium?.
Questionable assignment: Lentin and Williams (1981, p.14).
Age: Paleocene.
---------------------------------------------------------------------------------------------------
Original description: [Boltenhagen, 1977] (translated from French):
Polysphaeridium williereae nov. sp.
Ozouri Series, Paleocene, Port-Gentil (Gabon, Equatorial Africa)
DIAGNOSIS
Spherical or ovoid shell with numerous short tubular appendages, ending in a tuft or star-shaped crown of spinules. Apical archaeopyle.
DESCRIPTION
The subspherical or ovoid shell of our specimens is covered by fairly short appendages of the same length, ending in a tuft or crown of small spines. The tuft is composed of several tiny spines, joined at the base, thus forming a "brush." The crown is made up of a few (3, 4, or 5) of these filiform spines, located in a plane or directed upward or downward, which gives a "star-shaped" appearance to the ends of these appendages.
In addition, the tips of some appendages are sometimes simply acuminate. The total number of appendages is around 50. They are all tubular and are inserted by large conical bases onto a smooth or punctuated periphragm. At 800x magnification, this punctuation actually corresponds to fine granulation, also visible on the appendages.
The smooth endophragm isolates the appendages from the interior of the shell. The total thickness of the membrane is approximately 1µ.
At first glance, the archaeopyle is not obvious. However, the more or less zigzagging edges of the observed caps suggest that these are not accidental tears. To verify the position of the presumed archaeopyle, we measured the axes of 10 caps. These measurements made it possible to establish the ratio of the minor axis to the major axis: it is between 0.72 and 0.91 (arithmetic mean: 0.8) and would indicate that this is an apical archaeopyle.
OBSERVATIONS
This species is almost exclusively found in the preparation studied, but whole specimens are rather rare.
DIMENSIONS
Holotype: shell (with appendages): d' = 92 x 84 μ
shell (without appendages): d'' = 75 x 72 μ
appendages L = 11-14 μ
average thickness = 1-1.5 μ
crown of spines: d = 3-4 μ
Paratypes:
1) cap (without appendages): d = 67-55 μ
appendages L = 12-16 μ
2) shell (with appendages): d' = 82-75 μ
(without appendages): d'' = 60-57 μ
appendages: L = 14-18 μ
Based on 18 other specimens:
shell (major axis) = 58-80 μ
(minor axis) = 52-72 μ
appendages: L = 11-18 μ
COMPARISON
The specimens described bear resemblance to Hystrichosphaeridium microtriaina KLUMPP 1953 (p. 390, PI. 17, Figs. 6 and 7) in the appearance of the appendage tips; however, the latter differ in the detail of the shape and the number of terminal spines. Furthermore, the amendment by A. EISENACK 1963 (p. 263) places the considered species of E. KLUMPP in the genus Cordosphaeridium, characterized by the fibrousness of the membrane, which is not the case for the Gabonese species.
Stratigraphic and Geographic Position
Tertiary: Paleocene; Gabon (Port-Gentil and Fernan-Vaz).