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Alterbidinium prominense
From Fensome et al., 2019:
Alterbidinium prominense, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.44–45, pl.12, figs.5–6,9–11; text-fig.18e ex Williams and Fensome, 2016, p.139.
Holotype: Andreeva-Grigorovich et al., 2011, pl.12, figs.10–11; text-fig.18e, designated by Williams and Fensome (2016, p.139).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.44–45) since the holotype citation (pl.12, figs.5–6, 9–11 and text-fig.18e) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium prominense.
Age: Danian–Selandian.
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Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011]:
Alterbidinium prominense Vassilyeva sp. nov. Plate XII, 5, 6, 9-11; Fig. 18, d
Name. From Latin prominens, a protruding part of something (here the apical protrusion in relation to the structure of the apical horn, has the shape of a cone).
Diagnosis. Peridiniod circumcavate oval cyst small to intermediate size. Apical horn pyramidal, comparatively prominent, narrow. Left antapical horn well-developed, of wide triangular shape. Endocyst rounded-oval. Periphragm smooth, thin, dense, transparent. Endophragm more dense, smooth or weakly scabrate. Periarcheopyle wide-hexagonal, intercalary or intercalary-precingular. Perioperculum attached. Paracingulum expressed by prominent furrow and thin fold of perifragm. Parasulcus not expressed.
Description: Pericysta is round-oval in shape. Epicyst is long, approximately equal to the hypocyst. The epicyst is rounded with an apical horn protruding in the shape of a pyramid. Sometimes "shoulders" in the form of a slight bend are observed on the hypocyst. The hypocyst is asymmetrical, trapezoidal, with a well-developed pointed left antapical horn, shaped like a wide triangle. The right antapical horn is significantly reduced, pointed or not expressed. The endocyst is rounded-oval, rounded-pentagonal. The periphragm is comparatively dense, smooth or smoothed-tuberculate. The endophragm is dense, tuberculate-shagreen. Inclusions of organic material in the form of individual tubercles are observed on the surface of the endophragm. The pericoel is comparatively narrow, expanding only in the area of the hypocoel. The periarchaeopyle is comparatively wide, hexagonal in shape, intercalary or intercalary-precingular. The periarchaeopile is formed by plates Ia or 2a. The perioperculum is attached. The paracingulum is represented by a double wide groove, usually well projecting, sometimes smoother, and also by a thin fold of the periphragm. The parasulcus is not expressed.
Holotype. Plate XII, 5, 6, 9-11; Fig. 18, d. Prep. Cf. Salt. 46a-2003.
Location. Saltanovo outcrop, Lyalya River, Talitskaya (Ivdelskaya) suite (Sverdlovsk region, Serovsky district, Saltanovo village).
Dimensions: Holotype: pericyst length - 58; pericyst width - 56; endocyst diameter - 44. Other specimens (3 specimens): pericyst length - 60-55; endocyst diameter - 58-55; endocyst length - 50-43; endocyst width - 50-42.
Comparison. This species is comparable to the species Alterbidinium compactum sp. nov., but differs in its narrow, persistent pericoel, the shape of the apical horn, and the structure of the hypocyst.
Distribution. Russia, Middle Trans-Urals, Talitskaya suite. Paleocene (Danian-Selandian).
Alterbidinium prominense, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.44–45, pl.12, figs.5–6,9–11; text-fig.18e ex Williams and Fensome, 2016, p.139.
Holotype: Andreeva-Grigorovich et al., 2011, pl.12, figs.10–11; text-fig.18e, designated by Williams and Fensome (2016, p.139).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.44–45) since the holotype citation (pl.12, figs.5–6, 9–11 and text-fig.18e) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium prominense.
Age: Danian–Selandian.
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Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011]:
Alterbidinium prominense Vassilyeva sp. nov. Plate XII, 5, 6, 9-11; Fig. 18, d
Name. From Latin prominens, a protruding part of something (here the apical protrusion in relation to the structure of the apical horn, has the shape of a cone).
Diagnosis. Peridiniod circumcavate oval cyst small to intermediate size. Apical horn pyramidal, comparatively prominent, narrow. Left antapical horn well-developed, of wide triangular shape. Endocyst rounded-oval. Periphragm smooth, thin, dense, transparent. Endophragm more dense, smooth or weakly scabrate. Periarcheopyle wide-hexagonal, intercalary or intercalary-precingular. Perioperculum attached. Paracingulum expressed by prominent furrow and thin fold of perifragm. Parasulcus not expressed.
Description: Pericysta is round-oval in shape. Epicyst is long, approximately equal to the hypocyst. The epicyst is rounded with an apical horn protruding in the shape of a pyramid. Sometimes "shoulders" in the form of a slight bend are observed on the hypocyst. The hypocyst is asymmetrical, trapezoidal, with a well-developed pointed left antapical horn, shaped like a wide triangle. The right antapical horn is significantly reduced, pointed or not expressed. The endocyst is rounded-oval, rounded-pentagonal. The periphragm is comparatively dense, smooth or smoothed-tuberculate. The endophragm is dense, tuberculate-shagreen. Inclusions of organic material in the form of individual tubercles are observed on the surface of the endophragm. The pericoel is comparatively narrow, expanding only in the area of the hypocoel. The periarchaeopyle is comparatively wide, hexagonal in shape, intercalary or intercalary-precingular. The periarchaeopile is formed by plates Ia or 2a. The perioperculum is attached. The paracingulum is represented by a double wide groove, usually well projecting, sometimes smoother, and also by a thin fold of the periphragm. The parasulcus is not expressed.
Holotype. Plate XII, 5, 6, 9-11; Fig. 18, d. Prep. Cf. Salt. 46a-2003.
Location. Saltanovo outcrop, Lyalya River, Talitskaya (Ivdelskaya) suite (Sverdlovsk region, Serovsky district, Saltanovo village).
Dimensions: Holotype: pericyst length - 58; pericyst width - 56; endocyst diameter - 44. Other specimens (3 specimens): pericyst length - 60-55; endocyst diameter - 58-55; endocyst length - 50-43; endocyst width - 50-42.
Comparison. This species is comparable to the species Alterbidinium compactum sp. nov., but differs in its narrow, persistent pericoel, the shape of the apical horn, and the structure of the hypocyst.
Distribution. Russia, Middle Trans-Urals, Talitskaya suite. Paleocene (Danian-Selandian).