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Palaeocystodinium stockmansii
Palaeocystodinium stockmansii Boltenhagen, 1977
Holotype: Boltenhagen, 1977, pl. 23, figs.1a-b
Age: Campanian-Maastrichtian
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Original description: [Boltenhagen, 1977] (translated from French):
Palaeocystodinium stockmansii nov. sp.
Ewongué and Pointe-Clairette Series, Maastrichtian, Campanian; Port-Gentil (Gabon, Equatorial Africa).
DIAGNOSIS
Thin, smooth, ellipsoidal theca, with two short extensions and enclosing a thin, oval capsule, rounded at the poles; intercalary, subtrapezoidal-hexagonal archaeopyle; no cingulum, sulcus, or tabulation.
DESCRIPTION
In its typical state, the body of the theca, with a regular oval outline, is equipped with two short, horn-like polar extensions. In the dorsiventral position, the ratio of the theca diameter to the polar axis is 3/4. In profile, this ratio is reduced to 3/5. The flattening of the theca thus appears, and its shape then approaches an ellipsoid. The capsule of the same shape is separated from the theca by a margin and only detaches completely from it at the poles. The outer membrane and that of the capsule are very thin, a slight punctuation is sometimes perceptible on the latter. Neither the cingulum, nor the sulcus, nor the traces of the tabulation are perceptible. The archaeopyle or the sutures of the operculum, of roughly trapezoidal outline, are frequently observed. Depending on the state of preservation of the specimen considered, we thus notice the three, four or five sides of a polygon, which makes it possible to reconstruct the original shape of the archaeopyle which is, in fact, hexagonal with two lower sides reduced against a large base; this shape is very comparable to the intercalary plate 2a of Peridinium according to W.R. EVlTT 1967 (p. 34, in text fig. 35). The two conical extensions are short and very often blunt or torn off. Their length is variable and depends on the size of the theca. According to the measurements of ten specimens with almost entire extensions, there is a ratio between the length of each extension and that of the polar axis of the theca, which is between approximately 1/4 and 1/5. Exceptionally, this ratio is reduced to 1/6. In addition, it would seem that, overall, the apical extension is slightly longer than the other. It is also worth noting the significant variations in size: the largest specimens are one and a half times larger than the small ones.
DIMENSIONS
Holotype: theca (with extensions): L = 109 μ
theca (without extensions): L' x l = 80 x 61 μ
capsule L'' x l' = 75 x 57 μ
extensions h = 12 - 14 μ
3 paratypes: theca (with extensions): L = 108 - 93 μ
theca (without extensions): L' x l = 75 x 62 μ; 87 x 52 μ; 106 x 69 μ
capsule L'' x l' = 73 x 60 μ; 78 x 48 μ; 104 x 64 μ
extensions h = 6 - 10 - > 15 μ
14 other specimens whose theca extensions are more or less damaged or torn off:
theca (without extensions): L = 75 x 110 μ
l = 47 x 76 μ
capsule L' = 70 - 104 μ
l' = 45- 71 μ
COMPARISON
Compared to the generotype P. golzowense ALB. 1961 (p. 20, PI. 7, Fig. 10-12), the described species is much stockier and has short, conical processes, located on the poles and not tapered around the edges. Their length varies from one-quarter to one-fifth that of the polar axis of the theca; whereas it is half or almost equal to the length of the theca of the generotype.
Stratigraphic and Geographic Position
Upper Cretaceous: Campanian, Maastrichtian; Gabon (Port-Gentil, Feman-Vaz, and North Ogooué).
Lower Tertiary: Paleocene; Gabon (Port-Gentil and Feman-Vaz).
Holotype: Boltenhagen, 1977, pl. 23, figs.1a-b
Age: Campanian-Maastrichtian
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Original description: [Boltenhagen, 1977] (translated from French):
Palaeocystodinium stockmansii nov. sp.
Ewongué and Pointe-Clairette Series, Maastrichtian, Campanian; Port-Gentil (Gabon, Equatorial Africa).
DIAGNOSIS
Thin, smooth, ellipsoidal theca, with two short extensions and enclosing a thin, oval capsule, rounded at the poles; intercalary, subtrapezoidal-hexagonal archaeopyle; no cingulum, sulcus, or tabulation.
DESCRIPTION
In its typical state, the body of the theca, with a regular oval outline, is equipped with two short, horn-like polar extensions. In the dorsiventral position, the ratio of the theca diameter to the polar axis is 3/4. In profile, this ratio is reduced to 3/5. The flattening of the theca thus appears, and its shape then approaches an ellipsoid. The capsule of the same shape is separated from the theca by a margin and only detaches completely from it at the poles. The outer membrane and that of the capsule are very thin, a slight punctuation is sometimes perceptible on the latter. Neither the cingulum, nor the sulcus, nor the traces of the tabulation are perceptible. The archaeopyle or the sutures of the operculum, of roughly trapezoidal outline, are frequently observed. Depending on the state of preservation of the specimen considered, we thus notice the three, four or five sides of a polygon, which makes it possible to reconstruct the original shape of the archaeopyle which is, in fact, hexagonal with two lower sides reduced against a large base; this shape is very comparable to the intercalary plate 2a of Peridinium according to W.R. EVlTT 1967 (p. 34, in text fig. 35). The two conical extensions are short and very often blunt or torn off. Their length is variable and depends on the size of the theca. According to the measurements of ten specimens with almost entire extensions, there is a ratio between the length of each extension and that of the polar axis of the theca, which is between approximately 1/4 and 1/5. Exceptionally, this ratio is reduced to 1/6. In addition, it would seem that, overall, the apical extension is slightly longer than the other. It is also worth noting the significant variations in size: the largest specimens are one and a half times larger than the small ones.
DIMENSIONS
Holotype: theca (with extensions): L = 109 μ
theca (without extensions): L' x l = 80 x 61 μ
capsule L'' x l' = 75 x 57 μ
extensions h = 12 - 14 μ
3 paratypes: theca (with extensions): L = 108 - 93 μ
theca (without extensions): L' x l = 75 x 62 μ; 87 x 52 μ; 106 x 69 μ
capsule L'' x l' = 73 x 60 μ; 78 x 48 μ; 104 x 64 μ
extensions h = 6 - 10 - > 15 μ
14 other specimens whose theca extensions are more or less damaged or torn off:
theca (without extensions): L = 75 x 110 μ
l = 47 x 76 μ
capsule L' = 70 - 104 μ
l' = 45- 71 μ
COMPARISON
Compared to the generotype P. golzowense ALB. 1961 (p. 20, PI. 7, Fig. 10-12), the described species is much stockier and has short, conical processes, located on the poles and not tapered around the edges. Their length varies from one-quarter to one-fifth that of the polar axis of the theca; whereas it is half or almost equal to the length of the theca of the generotype.
Stratigraphic and Geographic Position
Upper Cretaceous: Campanian, Maastrichtian; Gabon (Port-Gentil, Feman-Vaz, and North Ogooué).
Lower Tertiary: Paleocene; Gabon (Port-Gentil and Feman-Vaz).