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Kallosphaeridium nigeriense
From Fensome et al., 2019:
Kallosphaeridium nigeriense JJan du Chêne et al., 1985a, p.12, pl.4, figs.1–13. Holotype: Jan du Chêne et al., 1985a, pl.4, figs.1–3.
Age: Late Paleocene (Thanetian)–Early Eocene (Ypresian).
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Original Description: Jan du Chene et al. 1985a, p. 12
Cysts subspherical, proximate, with a smooth, thin (less than 1 µm) autophragm which is commonly folded and bears numerous nontabular, slender acuminate spines. Spines are smooth, 3 to 6 µm in length (average about 4 µm), tapered, and have basal diameters of approximately 1 to 2 µm. The archeopyle is type [4AI] @, attached by a narrow isthmus, or more frequently, by the isthmus and the last precingular paraplate which fails to separate from the adjacent apical paraplates. Opercula are small relative to cyst diameter; OW/CD ratio = 0.41 to 0.35. Principal archeopyle suture zigzag; accessory sutures between precingular paraplates unusually long, rarely developed on opercula. Precingular paraplates are peaked anteriorly except for 2", which is flat-topped. Other expressions of paratabulation are faint or absent, including those indicating a paracingulum and a parasulcus. Diameter 56 to 66 µm, 9 specimens measured.
Comparison: The spinate ornamentation on Kallosphaeridium nigeriaense separates it from other species in the genus (see Table 1). Species most similar to it are K. coninckii, which has shorter and slenderer projections; K. biornatum, whose spines are smaller, scattered and rest on a punctoreticulate surface, and K. yorubaense, whose ornamentation consists of densely arranged, short, rod-like, or straight, or curved projections.
Synonymy:
1985 - Kallosphaeridium sp. cf. K. orchiesense De Coninck, 1975. Jan Du Chene &
Adediran, p. 22; pl. 1l, fig. 7 - 12; pl. 12, fig. 8 - 10.
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Kallosphaeridium nigeriense JJan du Chêne et al., 1985a, p.12, pl.4, figs.1–13. Holotype: Jan du Chêne et al., 1985a, pl.4, figs.1–3.
Age: Late Paleocene (Thanetian)–Early Eocene (Ypresian).
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Original Description: Jan du Chene et al. 1985a, p. 12
Cysts subspherical, proximate, with a smooth, thin (less than 1 µm) autophragm which is commonly folded and bears numerous nontabular, slender acuminate spines. Spines are smooth, 3 to 6 µm in length (average about 4 µm), tapered, and have basal diameters of approximately 1 to 2 µm. The archeopyle is type [4AI] @, attached by a narrow isthmus, or more frequently, by the isthmus and the last precingular paraplate which fails to separate from the adjacent apical paraplates. Opercula are small relative to cyst diameter; OW/CD ratio = 0.41 to 0.35. Principal archeopyle suture zigzag; accessory sutures between precingular paraplates unusually long, rarely developed on opercula. Precingular paraplates are peaked anteriorly except for 2", which is flat-topped. Other expressions of paratabulation are faint or absent, including those indicating a paracingulum and a parasulcus. Diameter 56 to 66 µm, 9 specimens measured.
Comparison: The spinate ornamentation on Kallosphaeridium nigeriaense separates it from other species in the genus (see Table 1). Species most similar to it are K. coninckii, which has shorter and slenderer projections; K. biornatum, whose spines are smaller, scattered and rest on a punctoreticulate surface, and K. yorubaense, whose ornamentation consists of densely arranged, short, rod-like, or straight, or curved projections.
Synonymy:
1985 - Kallosphaeridium sp. cf. K. orchiesense De Coninck, 1975. Jan Du Chene &
Adediran, p. 22; pl. 1l, fig. 7 - 12; pl. 12, fig. 8 - 10.
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