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Kallosphaeridium yorubaense
Kallosphaeridium yorubaense Jan du Chene and Adediran, 1985
Holotype: Jan du Chene and Adediran, 1985, pl.6, fig.11-12
Locus typicus: Benin-Ore Highway, Km 41, Nigeria
Stratum typicum: Late Palaeocene-Early Eocene
Original description: Jan du Chene and Adediran, 1985, p. 22
Cyst spherical to subspherical with a thin, commonly folded autophragm supporting numerous, and dense, low and thin projections. The archeopyle seems apical only (type tAa) but a close study of the zig-zag sutures of the attached operculum reveals the presence of an anterior intercalary paraplate (text-fig. 7). This paraplate is situated between the second and third apical and the third and fourth precingular paraplates. This anterior intercalary paraplate remains attached to the opercula. Long accessory sutures are generally observable between the six precingular paraplates. Accessory sutures may also occur between the opercular paraplates or may be suggested by fragile zones of thinning. Presence of small preapical paraplate(s) is also possible (plate 10, fig. 1 and 3). Paratabulation formula could correspond to pr(?), 4", 1a, 6"; hypocystal tabulation not indicated. Dimensions: Range Diameter of the cyst 56-66 Ám. Length of the projections 5-1,5 Ám. Number of specimens measured: 25
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Jan du Chene et al. 1985a, p. 13: Kallosphaeridium yorubaense
The abundant and well preserved specimens of this species were indispensible in deciphering the archeopyle configurations and the overall morphology of Kallosphaeridium. This then lead to the investigation of previously described species, which in turn, resulted in this contribution. The description below and the illustrations herein, although providing additional morphologic details, do not differ significantly from the original species description.
Description: Jan du Chene et al. 1985a, p. 13: Kallosphaeridium yorubaense
Cysts suspherical proximate with a thin (less than 1 llm) autophragm which is commonly folded and supports numerous, low, slender, elongate projections (pl. 7), which impart a punctoreticulate to somewhat granulal texture to the cvsts when viewed in bright field microscopy. The archeopyle is type [4AI] @, attached by a narrow isthmus. Opercula are small relative to cyst diameter; OW/CD ratio = 0.41 to 0.32, average = 0.38. Principal archeopyle suture is zigzag, accessory archeopyle sutures between precingulars generally long, and accessory sutures on the operculum are usually undeveloped or reduced to notches. Parasutural features on opercula may be depicted by faint lines (depressions ?) or fragile zones of thinning. Paratabulation of epicyst is 0-2 pr?, 4", la, 6"; paratabulation of hypocyst is not known. The presence of preapical paraplates is suggested by a small thickened area near the center of the operculum on occasional specimens. Partial limits of other epicystal paraplates are indicated by the archeopyle margins, archeopyle sutures and notches, and when present, by the parasutural features. Precingular paraplates are peaked anteriorly, except for 2", which is flat-topped. Paracingulum and parasulcus are not discernible. Diameter, between 56 and 66 Ám; 25 specimens measured.
Comment: Jan du Chene et al. 1985a, p. 13:
On a few specimens of Kallosphaeridium yorubaense parasutures 1"/2", 3"/4", and 4"/1", can be traced almost to their point of intersection or to the margin of a poorly delimited preapical area. In contrast, the intersection of parasutures 2"/1a and la/3" is between the preapical area (or the projected intersection of 1"/2", 3"/4" and 4"/1") and the peak of la. Much more commonly, however, the parasutures are incomplete or not developed and their locations and directions are indicated solely by accessory archeopyle sutures. This is so on most specimens of K. yorubaense as well as all of the other species for which we had specimens.
Holotype: Jan du Chene and Adediran, 1985, pl.6, fig.11-12
Locus typicus: Benin-Ore Highway, Km 41, Nigeria
Stratum typicum: Late Palaeocene-Early Eocene
Original description: Jan du Chene and Adediran, 1985, p. 22
Cyst spherical to subspherical with a thin, commonly folded autophragm supporting numerous, and dense, low and thin projections. The archeopyle seems apical only (type tAa) but a close study of the zig-zag sutures of the attached operculum reveals the presence of an anterior intercalary paraplate (text-fig. 7). This paraplate is situated between the second and third apical and the third and fourth precingular paraplates. This anterior intercalary paraplate remains attached to the opercula. Long accessory sutures are generally observable between the six precingular paraplates. Accessory sutures may also occur between the opercular paraplates or may be suggested by fragile zones of thinning. Presence of small preapical paraplate(s) is also possible (plate 10, fig. 1 and 3). Paratabulation formula could correspond to pr(?), 4", 1a, 6"; hypocystal tabulation not indicated. Dimensions: Range Diameter of the cyst 56-66 Ám. Length of the projections 5-1,5 Ám. Number of specimens measured: 25
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Jan du Chene et al. 1985a, p. 13: Kallosphaeridium yorubaense
The abundant and well preserved specimens of this species were indispensible in deciphering the archeopyle configurations and the overall morphology of Kallosphaeridium. This then lead to the investigation of previously described species, which in turn, resulted in this contribution. The description below and the illustrations herein, although providing additional morphologic details, do not differ significantly from the original species description.
Description: Jan du Chene et al. 1985a, p. 13: Kallosphaeridium yorubaense
Cysts suspherical proximate with a thin (less than 1 llm) autophragm which is commonly folded and supports numerous, low, slender, elongate projections (pl. 7), which impart a punctoreticulate to somewhat granulal texture to the cvsts when viewed in bright field microscopy. The archeopyle is type [4AI] @, attached by a narrow isthmus. Opercula are small relative to cyst diameter; OW/CD ratio = 0.41 to 0.32, average = 0.38. Principal archeopyle suture is zigzag, accessory archeopyle sutures between precingulars generally long, and accessory sutures on the operculum are usually undeveloped or reduced to notches. Parasutural features on opercula may be depicted by faint lines (depressions ?) or fragile zones of thinning. Paratabulation of epicyst is 0-2 pr?, 4", la, 6"; paratabulation of hypocyst is not known. The presence of preapical paraplates is suggested by a small thickened area near the center of the operculum on occasional specimens. Partial limits of other epicystal paraplates are indicated by the archeopyle margins, archeopyle sutures and notches, and when present, by the parasutural features. Precingular paraplates are peaked anteriorly, except for 2", which is flat-topped. Paracingulum and parasulcus are not discernible. Diameter, between 56 and 66 Ám; 25 specimens measured.
Comment: Jan du Chene et al. 1985a, p. 13:
On a few specimens of Kallosphaeridium yorubaense parasutures 1"/2", 3"/4", and 4"/1", can be traced almost to their point of intersection or to the margin of a poorly delimited preapical area. In contrast, the intersection of parasutures 2"/1a and la/3" is between the preapical area (or the projected intersection of 1"/2", 3"/4" and 4"/1") and the peak of la. Much more commonly, however, the parasutures are incomplete or not developed and their locations and directions are indicated solely by accessory archeopyle sutures. This is so on most specimens of K. yorubaense as well as all of the other species for which we had specimens.