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Alterbidinium nummuliforme
From Fensome et al., 2019:
Alterbidinium nummuliforme, Vasilyeva in Andreeva-Grigorovich et al., 2011, p. 43, pl.11, figs.15–17; text-fig.18c ex Williams et al., 2017, p.67.
Holotype: Andreeva-Grigorovich et al., 2011, pl.11, fig.15; text-fig.18c, designated by Williams and Fensome (2016, p.138).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.43) since the holotype citation (pl.11, figs.15–17 and text-fig.18c) includes more than one specimen.
The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium nummuliforme.
Age: Thanetian–Ypresian.
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Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011] (translated from Russian with Google):
Alterbidinium nummuliforme Vassilyeva sp. nov.
Name: From Latin nummulus - a small coin.
Diagnosis. Peridinioid circumcavate almost round cyst of intermediate size. Endocyst circular. Periphragm thin, smooth, light, transparent. Endophragm dense, coarse granular. Periarcheopyle elongate, hexagonal, intercalary. Perioperculum attached. Paracingulum weakly expressed by wide furrow. Parasulcus marked by thin semicircular folds of periphragm on hypocyst ventral side.
Description. The pericyst is almost round. The epicyst and hypocyst are of equal length. The apical horn protrudes slightly above the surface of the cyst as a wide truncated triangle. Usually, the apical horn is slightly inclined, which gives the epicyst an asymmetrical shape. The hypocyst is usually asymmetrical. The left antapical horn is developed (pointed), the right one is reduced. There are specimens with antapical horns of almost equal length. The endocyst is almost perfectly round, occupies most of the pericyst. The periphragm is thin, light, transparent, smooth. The endophragm is dense, two-layered, thicker, coarse-grained or unclearly tuberculate. On the endophragm, in the center of the endocyst, inclusions of organic matter in the form of large tubercles are almost always observed. The pericoel is pronounced, very narrow. The epicoel is somewhat expanded. The hypocoel expands only in the area of the antapical horn. The paracingulum is poorly expressed: a wide flat groove and the finest cord-like folds on the periphragm are distinguishable. The periarchaeopile is elongated, rounded-hexagonal, difficult to distinguish, of the intercalary type. The perioperculum is attached. The parasulcus is indicated by thin rounded folds of the periphragm on the hypocyst.
Holotype. Plate XI, 15-17; Fig. 18, v. Prep. Persh. 126-2003, IGIG UB RAS.
Location. Pershinsky section, Serov suite (Sverdlovsk region, Dalmatovo village).
Dimensions (µm). Holotype: pericyst length 46.1; pericyst width 36.3; endocyst diameter 33.3; endophragm thickness 1.5; paracingulum width - 5. Other specimens (3 specimens): pericyst length 56.1; pericyst width 41.3; endocyst diameter - 36.3.
Comparison. In general structure, size, and ratio of apical and antapical horns it resembles representatives of the genus Senegalinium, but differs in the structure of the archeopyle and antapical horns typical of the genus Alterbidinium.
Distribution. Russia, Trans-Urals, Serov Formation. Upper Paleocene (Thanetian), 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. 43) since the holotype citation (pl. 11, figs 15-17 and text-fig. 18c) includes more than one specimen. Here the holotype is clearly designated, thus validating the name Alterbidinium nummuliforme. Age: Thanetian-Ypresian.
Alterbidinium nummuliforme, Vasilyeva in Andreeva-Grigorovich et al., 2011, p. 43, pl.11, figs.15–17; text-fig.18c ex Williams et al., 2017, p.67.
Holotype: Andreeva-Grigorovich et al., 2011, pl.11, fig.15; text-fig.18c, designated by Williams and Fensome (2016, p.138).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.43) since the holotype citation (pl.11, figs.15–17 and text-fig.18c) includes more than one specimen.
The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium nummuliforme.
Age: Thanetian–Ypresian.
---------------------------------------------------------------------------------------------------
Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011] (translated from Russian with Google):
Alterbidinium nummuliforme Vassilyeva sp. nov.
Name: From Latin nummulus - a small coin.
Diagnosis. Peridinioid circumcavate almost round cyst of intermediate size. Endocyst circular. Periphragm thin, smooth, light, transparent. Endophragm dense, coarse granular. Periarcheopyle elongate, hexagonal, intercalary. Perioperculum attached. Paracingulum weakly expressed by wide furrow. Parasulcus marked by thin semicircular folds of periphragm on hypocyst ventral side.
Description. The pericyst is almost round. The epicyst and hypocyst are of equal length. The apical horn protrudes slightly above the surface of the cyst as a wide truncated triangle. Usually, the apical horn is slightly inclined, which gives the epicyst an asymmetrical shape. The hypocyst is usually asymmetrical. The left antapical horn is developed (pointed), the right one is reduced. There are specimens with antapical horns of almost equal length. The endocyst is almost perfectly round, occupies most of the pericyst. The periphragm is thin, light, transparent, smooth. The endophragm is dense, two-layered, thicker, coarse-grained or unclearly tuberculate. On the endophragm, in the center of the endocyst, inclusions of organic matter in the form of large tubercles are almost always observed. The pericoel is pronounced, very narrow. The epicoel is somewhat expanded. The hypocoel expands only in the area of the antapical horn. The paracingulum is poorly expressed: a wide flat groove and the finest cord-like folds on the periphragm are distinguishable. The periarchaeopile is elongated, rounded-hexagonal, difficult to distinguish, of the intercalary type. The perioperculum is attached. The parasulcus is indicated by thin rounded folds of the periphragm on the hypocyst.
Holotype. Plate XI, 15-17; Fig. 18, v. Prep. Persh. 126-2003, IGIG UB RAS.
Location. Pershinsky section, Serov suite (Sverdlovsk region, Dalmatovo village).
Dimensions (µm). Holotype: pericyst length 46.1; pericyst width 36.3; endocyst diameter 33.3; endophragm thickness 1.5; paracingulum width - 5. Other specimens (3 specimens): pericyst length 56.1; pericyst width 41.3; endocyst diameter - 36.3.
Comparison. In general structure, size, and ratio of apical and antapical horns it resembles representatives of the genus Senegalinium, but differs in the structure of the archeopyle and antapical horns typical of the genus Alterbidinium.
Distribution. Russia, Trans-Urals, Serov Formation. Upper Paleocene (Thanetian), Lower Eocene (Ypresian).
------------------------------------------------------------------------------------
Remarks by Williams and Fensome, 2016 (p. 138):
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p. 43) since the holotype citation (pl. 11, figs 15-17 and text-fig. 18c) includes more than one specimen. Here the holotype is clearly designated, thus validating the name Alterbidinium nummuliforme. Age: Thanetian-Ypresian.