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Chatangiella eminens
Chatangiella eminens, Pearce, 2010, p.67, pl.2, figs.1–6.
Type locality and horizon: Trunch borehole, Norfolk, UK; 331.9–332.0 m, Burnham–Flamborough Chalk (undifferentiated), low Uintacrinus socialis Zone (low upper Santonian).
Holotype: Pearce, 2010, pl.2, figs.1–6.
Age: middle to late Santonian.
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Original description: [Pearce, 2010, p.67]:
Diagnosis:
A species of Chatangiella possessing prominent spines on the paracingulum that are particularly well developed at the ambitus. Shorter spines are arranged in intratabular fields on the pre- and postcingular paraplates which may fuse on the margin of the pentapartite paracingulum and be randomly (but rarely) scattered elsewhere.
Description:
Medium-sized to large cornucavate peridinioid dinoflagellate cyst.
The wall is two-layered composed of a smooth to finely granular (1 μm thick) endophragm and a smooth to finely granular (w0.5 μm thick) periphragm that forms solid penitabular spines.
The spines are generally 2–4 μm in length, simple, evexate to capitate, longest when adjacent to paracingulum and are conspicuously long at the ambitus of the paracingulum. The spines are typically arranged in intratabular fields particularly on the pre- and postcingular paraplates and fuse on the paracingular margin where they demarcate a pentapartite paracingulum. Rare spines may also be randomly scattered over the pericyst. The pericyst is ventrodorsally compressed, longitudinally elongate, forming a short and blunt apical horn, two antapical horns (right antapical horn shorter), and a slight bulge around the paracingulum. Below the apical horn, the epicystal ambitus is convex with weakly to moderately well-developed rounded to sub-angular shoulders.
From the paracingulum to the antapical horns, the ambitus of the hypocystal is concave to occasionally straight.
The endocyst is sub-spherical to ovoidal, and follows the general shape of the pericyst. The left endo-antapical horn protrudes slightly into the antapical pericoel, the right endo-antapical horn is reduced.
The paratabulation is incompletely indicated by the intratabular clustering of spines and the position of the archaeopyle: x', 3a, 7", ?c, 5'", ?2". The parasulcus is indicated by a deep longitudinal depression.
The peri-archaeopyle is intercalary (Type I, operculum detached) and formed by the loss of an iso-thetaform to iso-deltaform 2a paraplate. The endo-archaeopyle type has not been determined.
Affinities:
This species most closely resembles Chatangiella madura Lentin & Williams, 1976 (see Cookson & Eisenack, 1970, pl. 11, fig. 10) but differs by possessing longer and more strongly developed paracingular spines at the ambitus.
Type locality and horizon: Trunch borehole, Norfolk, UK; 331.9–332.0 m, Burnham–Flamborough Chalk (undifferentiated), low Uintacrinus socialis Zone (low upper Santonian).
Holotype: Pearce, 2010, pl.2, figs.1–6.
Age: middle to late Santonian.
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Original description: [Pearce, 2010, p.67]:
Diagnosis:
A species of Chatangiella possessing prominent spines on the paracingulum that are particularly well developed at the ambitus. Shorter spines are arranged in intratabular fields on the pre- and postcingular paraplates which may fuse on the margin of the pentapartite paracingulum and be randomly (but rarely) scattered elsewhere.
Description:
Medium-sized to large cornucavate peridinioid dinoflagellate cyst.
The wall is two-layered composed of a smooth to finely granular (1 μm thick) endophragm and a smooth to finely granular (w0.5 μm thick) periphragm that forms solid penitabular spines.
The spines are generally 2–4 μm in length, simple, evexate to capitate, longest when adjacent to paracingulum and are conspicuously long at the ambitus of the paracingulum. The spines are typically arranged in intratabular fields particularly on the pre- and postcingular paraplates and fuse on the paracingular margin where they demarcate a pentapartite paracingulum. Rare spines may also be randomly scattered over the pericyst. The pericyst is ventrodorsally compressed, longitudinally elongate, forming a short and blunt apical horn, two antapical horns (right antapical horn shorter), and a slight bulge around the paracingulum. Below the apical horn, the epicystal ambitus is convex with weakly to moderately well-developed rounded to sub-angular shoulders.
From the paracingulum to the antapical horns, the ambitus of the hypocystal is concave to occasionally straight.
The endocyst is sub-spherical to ovoidal, and follows the general shape of the pericyst. The left endo-antapical horn protrudes slightly into the antapical pericoel, the right endo-antapical horn is reduced.
The paratabulation is incompletely indicated by the intratabular clustering of spines and the position of the archaeopyle: x', 3a, 7", ?c, 5'", ?2". The parasulcus is indicated by a deep longitudinal depression.
The peri-archaeopyle is intercalary (Type I, operculum detached) and formed by the loss of an iso-thetaform to iso-deltaform 2a paraplate. The endo-archaeopyle type has not been determined.
Affinities:
This species most closely resembles Chatangiella madura Lentin & Williams, 1976 (see Cookson & Eisenack, 1970, pl. 11, fig. 10) but differs by possessing longer and more strongly developed paracingular spines at the ambitus.