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Alterbidinium simplex
From Fensome et al., 2019:
Alterbidinium simplex, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.47–48, pl.12, figs.1–4; text-fig.18h ex Williams and Fensome, 2016, p.139.
Holotype: Andreeva-Grigorovich et al., 2011, pl.12, figs.1–2; text-fig. 18h, designated by Williams and Fensome (2016, p.139).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.47–48) since the holotype citation (pl.12, figs.1–4 and text-fig.18h) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium simplex.
Age: Thanetian–Ypresian.
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Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011] (translated from Russian with Google):
Alterbidinium simplex Vassilyeva sp. nov.
Name: From Latin simplex - simple.
Diagnosis. Peridinioid circumcavate cyst of intermediate size. Pericyst of ovalis, pentagonal shape. Left antapical horn developed longer or antapical horns almost equal. Apical horn quite small. Endocyst large oval-pentagonal shape. Pericel narrow. Periphragm dark coloured, dense, granulated. Periarcheopyle wide, hexagonal, of intercalary type. Perioperculum attached. Paracingulum distinct broad. Parasulcus marked by large folds of periphragm.
Description. The pericyst is oval-pentagonal. The epicyst is equal in length to the hypocyst. The epicyst has rounded sides without bends. The apical horn protrudes slightly, its apex is truncated. The antapical horns may be almost equal in length, or the left antapical horn is somewhat more developed. The endocyst is large, elongated, oval-pentagonal. The periphragm is rather dense, indistinctly granular, transparent. The endophragm is very dense, thick, darker than the periphragm. The pericoel is well defined, narrow. The paracingulum is distinct, expressed by a wide groove with significantly raised edges and thin sutures on the periphragm. The periarchaeopile is wide, rounded-hectagonal, of the intercalary type. The perioperculum is attached. The parasulcus is expressed by two large folds on the periphragm.
Holotype. Plate XII, 1-4; Fig. 18, 3. Prep. Persh. 18a-2003.
Location. Pershinsky section, Serov suite (Sverdlovsk region, Dalmatovo village).
Dimensions (µm). Holotype: pericyst length 59.4; pericyst width 42.9; endocyst length 46.2; endocyst width 36.3; endophragm thickness 3.5; paracingulum width 5. Other specimens (3 specimens): pericyst length 60.2-58.5; pericyst width 43.0-42.6; endocyst length 45.4-44.8; endocyst width 38-36.
Comparison. Differs from other Alterbidinium species by the oval, elongated shape of the pericyst, dense oval-pentagonal endocyst and raised cingulum with a deep groove.
Distribution. Russia, Trans-Urals, Serov, Irbit suites. Upper Paleocene (Thanetian), Lower Eocene (Ypresian).
Alterbidinium simplex, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.47–48, pl.12, figs.1–4; text-fig.18h ex Williams and Fensome, 2016, p.139.
Holotype: Andreeva-Grigorovich et al., 2011, pl.12, figs.1–2; text-fig. 18h, designated by Williams and Fensome (2016, p.139).
This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.47–48) since the holotype citation (pl.12, figs.1–4 and text-fig.18h) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium simplex.
Age: Thanetian–Ypresian.
---------------------------------------------------------------------------------------------------
Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011] (translated from Russian with Google):
Alterbidinium simplex Vassilyeva sp. nov.
Name: From Latin simplex - simple.
Diagnosis. Peridinioid circumcavate cyst of intermediate size. Pericyst of ovalis, pentagonal shape. Left antapical horn developed longer or antapical horns almost equal. Apical horn quite small. Endocyst large oval-pentagonal shape. Pericel narrow. Periphragm dark coloured, dense, granulated. Periarcheopyle wide, hexagonal, of intercalary type. Perioperculum attached. Paracingulum distinct broad. Parasulcus marked by large folds of periphragm.
Description. The pericyst is oval-pentagonal. The epicyst is equal in length to the hypocyst. The epicyst has rounded sides without bends. The apical horn protrudes slightly, its apex is truncated. The antapical horns may be almost equal in length, or the left antapical horn is somewhat more developed. The endocyst is large, elongated, oval-pentagonal. The periphragm is rather dense, indistinctly granular, transparent. The endophragm is very dense, thick, darker than the periphragm. The pericoel is well defined, narrow. The paracingulum is distinct, expressed by a wide groove with significantly raised edges and thin sutures on the periphragm. The periarchaeopile is wide, rounded-hectagonal, of the intercalary type. The perioperculum is attached. The parasulcus is expressed by two large folds on the periphragm.
Holotype. Plate XII, 1-4; Fig. 18, 3. Prep. Persh. 18a-2003.
Location. Pershinsky section, Serov suite (Sverdlovsk region, Dalmatovo village).
Dimensions (µm). Holotype: pericyst length 59.4; pericyst width 42.9; endocyst length 46.2; endocyst width 36.3; endophragm thickness 3.5; paracingulum width 5. Other specimens (3 specimens): pericyst length 60.2-58.5; pericyst width 43.0-42.6; endocyst length 45.4-44.8; endocyst width 38-36.
Comparison. Differs from other Alterbidinium species by the oval, elongated shape of the pericyst, dense oval-pentagonal endocyst and raised cingulum with a deep groove.
Distribution. Russia, Trans-Urals, Serov, Irbit suites. Upper Paleocene (Thanetian), Lower Eocene (Ypresian).