Back
Alterbidinium compactum
From Fensome et al., 2019:
Alterbidinium compactum, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.40–42, pl.11, figs. 1–4; text-fig. 18a ex Williams and Fensome, 2016, p.138.
Holotype: Andreeva-Grigorovich et al., 2011, text-fig.18a, pl.11, fig.1, designated by Williams and Fensome (2016, p.138). This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.41) since the holotype citation (pl.11, figs.1–4 and text-fig.18a) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium compactum.
Age: Selandian.
---------------------------------------------------------------------------------------------------
Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011, p.40–42] (translated from Russian with Google Translate):
Alterbidinium compactum Vassilyeva sp. nov. — Plate XI, 1-4; Fig. 18, a
Name: From Latin compactus, compact.
Diagnosis. Peridinoid circumcavated oval-pentagonal cyst of small size. The apical horn protrudes slightly, pointed. The left antapical horn is well developed, the right one is almost completely reduced. The endocyst is round. The periphragm is thin, transparent. The endophragm is rather dense, thin, smooth or unclearly tuberculate. The periarcheopyle is wide, hexagonal, intercalary type. The perioperculum is attached. The paracingulum is distinct, protruding. The parasulcus is not distinguishable.
Diagnosis. Peridinioid circumcavate oval-pentagonal small-sized cyst. Apical horn weakly prominent, sharpened. Left antapical horn well developed, right one almost reduced. Endocyst round. Periphragm thin, transparent. Endo-phragm quite dense, thin, smooth or weakly scabrate. Periarcheopyle wide, he-xagonal, intercalary. Perioperculum attached. Paracingulum distinct, prominent. Parasulcus indistinguishable.
Description. The pericyst is oval-pentagonal. The epicyst is slightly longer than the hypocyst or equal to it. The "shoulders" are smoothly rounded. The apical horn protrudes slightly; its apex is drawn out and pointed. The hypocyst is trapezoid, asymmetrical; the sides gradually taper. The left (usually) antapical horn is well developed, pointed, the right one is practically reduced or slightly protruding, rounded. The endocyst is large, usually round, less often broadly oval. The periphragm is thin, transparent, dense, smooth. The endophragm is dense, smooth or unclearly tuberculate, slightly thicker and darker than the periphragm. The endophragm usually contains inclusions of organic material in the form of large grains and tubercles. The pericoel is well defined, sometimes asymmetrically narrowing in the area of the cingulum on one side of the cyst. The epicoel and hypocoel expand slightly. The periarchaeopyle is rounded-hexagonal, of the intercalary type (plates 1a or 2a). The periperculum is attached. The paracingulum is distinct, protruding in the form of a fairly wide, sagging groove, marked by a fold (sometimes double) on the periphragm. The parasulcus is not distinguishable.
Holotype. Table XI, 1-4, fig. 18, a. Rev. Wed. Saltanovo 46a-2003. Location. Saltanovo outcrop, r. Lyalya, Talitskan (Ivdel) formation (Sverdlovsk region, Serov district, Saltanovo village).
Dimensions (µm). Holotype: pericyst length 61; pericyst width 53; endocyst diameter 48. Other specimens (3 specimens): pericyst length 62-55; pericyst width 53-50; endocyst diameter 49-48.
Comparisons. Comparable to the species Alterbidinium rugulum, but significantly smaller in size; has a smooth periphragm, less relief [than] cingulum, the structure of the antapical horns has a different stratigraphic distribution.
Distribution. Russia, Middle Trans-Urals, Talitskaya, Ivdelskaya suites. Paleocene (Danian-Zealandian).
Alterbidinium compactum, Vasilyeva in Andreeva-Grigorovich et al., 2011, p.40–42, pl.11, figs. 1–4; text-fig. 18a ex Williams and Fensome, 2016, p.138.
Holotype: Andreeva-Grigorovich et al., 2011, text-fig.18a, pl.11, fig.1, designated by Williams and Fensome (2016, p.138). This name was not validly published by Vasilyeva in Andreeva-Grigorovich et al. (2011, p.41) since the holotype citation (pl.11, figs.1–4 and text-fig.18a) includes more than one specimen. The holotype was clearly designated in Williams and Fensome (2016), thus validating the name Alterbidinium compactum.
Age: Selandian.
---------------------------------------------------------------------------------------------------
Original description: [Vasilyeva in Andreeva-Grigorovich et al., 2011, p.40–42] (translated from Russian with Google Translate):
Alterbidinium compactum Vassilyeva sp. nov. — Plate XI, 1-4; Fig. 18, a
Name: From Latin compactus, compact.
Diagnosis. Peridinoid circumcavated oval-pentagonal cyst of small size. The apical horn protrudes slightly, pointed. The left antapical horn is well developed, the right one is almost completely reduced. The endocyst is round. The periphragm is thin, transparent. The endophragm is rather dense, thin, smooth or unclearly tuberculate. The periarcheopyle is wide, hexagonal, intercalary type. The perioperculum is attached. The paracingulum is distinct, protruding. The parasulcus is not distinguishable.
Diagnosis. Peridinioid circumcavate oval-pentagonal small-sized cyst. Apical horn weakly prominent, sharpened. Left antapical horn well developed, right one almost reduced. Endocyst round. Periphragm thin, transparent. Endo-phragm quite dense, thin, smooth or weakly scabrate. Periarcheopyle wide, he-xagonal, intercalary. Perioperculum attached. Paracingulum distinct, prominent. Parasulcus indistinguishable.
Description. The pericyst is oval-pentagonal. The epicyst is slightly longer than the hypocyst or equal to it. The "shoulders" are smoothly rounded. The apical horn protrudes slightly; its apex is drawn out and pointed. The hypocyst is trapezoid, asymmetrical; the sides gradually taper. The left (usually) antapical horn is well developed, pointed, the right one is practically reduced or slightly protruding, rounded. The endocyst is large, usually round, less often broadly oval. The periphragm is thin, transparent, dense, smooth. The endophragm is dense, smooth or unclearly tuberculate, slightly thicker and darker than the periphragm. The endophragm usually contains inclusions of organic material in the form of large grains and tubercles. The pericoel is well defined, sometimes asymmetrically narrowing in the area of the cingulum on one side of the cyst. The epicoel and hypocoel expand slightly. The periarchaeopyle is rounded-hexagonal, of the intercalary type (plates 1a or 2a). The periperculum is attached. The paracingulum is distinct, protruding in the form of a fairly wide, sagging groove, marked by a fold (sometimes double) on the periphragm. The parasulcus is not distinguishable.
Holotype. Table XI, 1-4, fig. 18, a. Rev. Wed. Saltanovo 46a-2003. Location. Saltanovo outcrop, r. Lyalya, Talitskan (Ivdel) formation (Sverdlovsk region, Serov district, Saltanovo village).
Dimensions (µm). Holotype: pericyst length 61; pericyst width 53; endocyst diameter 48. Other specimens (3 specimens): pericyst length 62-55; pericyst width 53-50; endocyst diameter 49-48.
Comparisons. Comparable to the species Alterbidinium rugulum, but significantly smaller in size; has a smooth periphragm, less relief [than] cingulum, the structure of the antapical horns has a different stratigraphic distribution.
Distribution. Russia, Middle Trans-Urals, Talitskaya, Ivdelskaya suites. Paleocene (Danian-Zealandian).