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Alterbidinium pentangulare
From Fensome et al., 2019:
Alterbidinium pentangulare, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.44, pl.11, figs.9–10; text-fig.18d ex Williams and Fensome, 2016, p.138.
Holotype: Andreeva-Grigorovich et al., 2011, pl.11, figs.10; text-fig. 18d, designated by Williams and Fensome (2016, p.138).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.44) since the holotype citation (pl.11, figs.9–10 and text-fig.18d) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium pentangulare.
Age:Ypresian.
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Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011] (translated from Russian with Google):
Alterbidinium pentangulare Vassilyeva sp. nov.
Name. From the Greek πέντε five, and Latin angularis – angular.
Diagnosis. Peridinioid circumcavate pentagonal cyst of intermediate size. Endocyst pentagonal, almost duplicates pericyst shape. Periphragm dense, lightly coloured. Periarcheopyle elongate, rounded, hexagonal. Perioperculum attached. Paracingulum clear, wide furrow. Parasulcus marked by weak folds of periphragm on hypocyst ventral side.
Description: The pericyst is symmetrical, with a distinct pentagonal shape.
The epicyst is somewhat longer than the hypocyst. The lateral sides of the epicyst are almost straight, with distinct bends, "shoulders". The hypocyst is symmetrical, with straight lateral sides, bent between the antapical horns. The endocyst is of a distinct pentagonal shape, repeating the shape of the pericyst. The periphragm is dense, granular, transparent. The endophragm is dense, thick, darker than the periphragm, with scattered tubercles. On the surface of the endophragm there are rare large inclusions of organic material. The pericoel is very narrow, sustained along the entire perimeter of the cyst. The epicoel and hypocoel are absent. The paracingulum is indistinct, elongated, hexagonal, of the intercalary type Ia (2a) or of the combined intercalary-precingulate type: 2a, 4". The parasulcus is barely indicated by a pair of thin short folds of the periphragm on the ventral side of the hypocyst.
Holotype. Plate XI, 9-10; Fig. 18, city of Prep. Korkino-109/1-2004.
Location. Korkinsky quarry, Irbit suite (Chelyabinsk region, Korkino settlement).
Dimensions (µm). Holotype: pericyst length - 68.2; paracingulum endocyst length - 55.4; pericyst width - 64.3; endocyst width 52.6; paracingulum width - 5. [?]
Comparison. It differs from other representatives of the genus Alterbidinium by its clear symmetrical shape of the pericyst, pentagonal endocyst, and narrow, persistent pericoel.
Distribution. Russia, Trans-Urals, Irbit Formation. Lower Eocene (Ypresian).
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Remarks by Williams and Fensome (2016, p.138):
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p. 44) since the holotype citation (pl. 11, figs 9-10 and text-fig. 18d) includes more than one specimen. Here the holotype is clearly designated, thus validating the name Alterbidinium pentangulare. Age: Ypresian.
Alterbidinium pentangulare, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.44, pl.11, figs.9–10; text-fig.18d ex Williams and Fensome, 2016, p.138.
Holotype: Andreeva-Grigorovich et al., 2011, pl.11, figs.10; text-fig. 18d, designated by Williams and Fensome (2016, p.138).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.44) since the holotype citation (pl.11, figs.9–10 and text-fig.18d) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium pentangulare.
Age:Ypresian.
---------------------------------------------------------------------------------------------------
Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011] (translated from Russian with Google):
Alterbidinium pentangulare Vassilyeva sp. nov.
Name. From the Greek πέντε five, and Latin angularis – angular.
Diagnosis. Peridinioid circumcavate pentagonal cyst of intermediate size. Endocyst pentagonal, almost duplicates pericyst shape. Periphragm dense, lightly coloured. Periarcheopyle elongate, rounded, hexagonal. Perioperculum attached. Paracingulum clear, wide furrow. Parasulcus marked by weak folds of periphragm on hypocyst ventral side.
Description: The pericyst is symmetrical, with a distinct pentagonal shape.
The epicyst is somewhat longer than the hypocyst. The lateral sides of the epicyst are almost straight, with distinct bends, "shoulders". The hypocyst is symmetrical, with straight lateral sides, bent between the antapical horns. The endocyst is of a distinct pentagonal shape, repeating the shape of the pericyst. The periphragm is dense, granular, transparent. The endophragm is dense, thick, darker than the periphragm, with scattered tubercles. On the surface of the endophragm there are rare large inclusions of organic material. The pericoel is very narrow, sustained along the entire perimeter of the cyst. The epicoel and hypocoel are absent. The paracingulum is indistinct, elongated, hexagonal, of the intercalary type Ia (2a) or of the combined intercalary-precingulate type: 2a, 4". The parasulcus is barely indicated by a pair of thin short folds of the periphragm on the ventral side of the hypocyst.
Holotype. Plate XI, 9-10; Fig. 18, city of Prep. Korkino-109/1-2004.
Location. Korkinsky quarry, Irbit suite (Chelyabinsk region, Korkino settlement).
Dimensions (µm). Holotype: pericyst length - 68.2; paracingulum endocyst length - 55.4; pericyst width - 64.3; endocyst width 52.6; paracingulum width - 5. [?]
Comparison. It differs from other representatives of the genus Alterbidinium by its clear symmetrical shape of the pericyst, pentagonal endocyst, and narrow, persistent pericoel.
Distribution. Russia, Trans-Urals, Irbit Formation. Lower Eocene (Ypresian).
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Remarks by Williams and Fensome (2016, p.138):
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p. 44) since the holotype citation (pl. 11, figs 9-10 and text-fig. 18d) includes more than one specimen. Here the holotype is clearly designated, thus validating the name Alterbidinium pentangulare. Age: Ypresian.