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Palaeoperidinium manumcooksoniae
Palaeoperidinium "manumcooksonii" (Corradini, 1973, p.176–177, pl.28, figs.4,6) Lentin and Williams, 1976, p.110.
Holotype: Corradini, 1973, pl.28, fig.4. Originally Astrocysta, subsequently Palaeoperidinium.
Taxonomic senior synonym: Palaeoperidinium cretaceum, according to Lentin and Williams (1976, p.110).
Age: Late Cretaceous–Paleocene.
Original diagnosis: Corradini, 1973, p. 176-177
Test flattened dorso-ventrally, pentagonal to circular in shape. One apical and two antapical horns fairly well developed. Thin periphragm and more consistent endophragm, often reabsorbed, normally in contact. Cingulum marked by noncontinuous ridges. Tabulation not developed. Archeopyle unknown.
Dimensions:
Holotype: maximum cingular width 100 µm, maximum length 110 µm. Range: maximum cingular width 85-(96)110) µm, maximum length 100-(109)-118 µm.
Original description: Corradini, 1973, p. 177
The sides of the test are often convex and the outline of the cyst may be therefore, circular. The periphragm is very thin and normally wrinkled; the endophragm outline the shape of the outer membrane but is often partially or entirely reabsorbed.
Apical horn in form of short cone, distally truncated; antapical horns of unequal length, fairly well developed. The two noncontinuous ridges marking the cingulum are often irregularly fused together. Sulcus weakly marked by low crests delineating a narrow hypotractal area. An archeopyle has never been observed.
Affinities:
Corradini, 1973, p. 177: Astrocysta manumcooksoni shows close similarities with A. cretacea (Pocock) from which it differs in having a more rounded outline and more reduced horns.
Holotype: Corradini, 1973, pl.28, fig.4. Originally Astrocysta, subsequently Palaeoperidinium.
Taxonomic senior synonym: Palaeoperidinium cretaceum, according to Lentin and Williams (1976, p.110).
Age: Late Cretaceous–Paleocene.
Original diagnosis: Corradini, 1973, p. 176-177
Test flattened dorso-ventrally, pentagonal to circular in shape. One apical and two antapical horns fairly well developed. Thin periphragm and more consistent endophragm, often reabsorbed, normally in contact. Cingulum marked by noncontinuous ridges. Tabulation not developed. Archeopyle unknown.
Dimensions:
Holotype: maximum cingular width 100 µm, maximum length 110 µm. Range: maximum cingular width 85-(96)110) µm, maximum length 100-(109)-118 µm.
Original description: Corradini, 1973, p. 177
The sides of the test are often convex and the outline of the cyst may be therefore, circular. The periphragm is very thin and normally wrinkled; the endophragm outline the shape of the outer membrane but is often partially or entirely reabsorbed.
Apical horn in form of short cone, distally truncated; antapical horns of unequal length, fairly well developed. The two noncontinuous ridges marking the cingulum are often irregularly fused together. Sulcus weakly marked by low crests delineating a narrow hypotractal area. An archeopyle has never been observed.
Affinities:
Corradini, 1973, p. 177: Astrocysta manumcooksoni shows close similarities with A. cretacea (Pocock) from which it differs in having a more rounded outline and more reduced horns.