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Saeptodinium
From Williams et al., 2017:
[Saeptodinium Harris, 1974, p. 162
Tax. jr. syn.: Sanshuia, according to Lentin and Williams (1989, p.326) — however, Mao Shaozhi et al. (1995, p.50) retained Sanshuia.
Type species: Saeptodinium gravattense, Harris, 1974 (pl.1, fig.2)]
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Original description: [Harris, 1974]:
Description:
Cavate dinoflagellate cysts of oval to peridinioid form with weakly developed apical and antapical horns. Endocorpus ovoidal. Pericorpus lacking tabulation and with indistinct trace of cingulum. Archeopyle formation not known. Ornament smooth to finely granulate.
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Modified description:
Stover and Evitt, 1978, p. 220:
Synopsis:
Cysts proximate, cornucavate or circumcavate, compressed subspherical to roundly peridinioid; pericyst usually with, rarely without, short apical and antapical horns or protrusions; paratabulation indicated by archeopyle only or by paracingulum and archeopyle; latter combination, Type "A3I3P"a.
Description:
Shape: Compressed subspherical to roundly peridinioid; pericyst usually has one short apical and two antapical horns or protrusions, less commonly one or more protrusions lacking.
Wall relationships: Cysts cornucavate to circumcavate.
Wall features: No parasutural features. Endophragm and periphragm smooth to faintly and uniformly ornamented.
Paratabulation: Expressed by archeopyle only or by archeopyle and paratabulation.
Archeopyle: Combination, Type "A3I3P"a, delimited apically and laterally by transapical suture; operculum attached antapically at paracingulum.
Paracingulum: Not indicated, or expressed faintly by low parallel, transverse, equatorial folds or linear marking on periphragm.
Parasulcus: Generally not indicated or expressed by vaguely defined depression on hypocyst.
Size: Small to intermediate.
Affinities:
Saeptodinium differs from Palaeoperidinium, which has the same archeopyle type as Saeptodinium, in lacking prominent apical and antapical horns, and in having a more rounded outline. Saeptodinium differs from Laciniadinium and Luxadinium in having a third apical paraplate involved in archeopyle formation.
[Saeptodinium Harris, 1974, p. 162
Tax. jr. syn.: Sanshuia, according to Lentin and Williams (1989, p.326) — however, Mao Shaozhi et al. (1995, p.50) retained Sanshuia.
Type species: Saeptodinium gravattense, Harris, 1974 (pl.1, fig.2)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Harris, 1974]:
Description:
Cavate dinoflagellate cysts of oval to peridinioid form with weakly developed apical and antapical horns. Endocorpus ovoidal. Pericorpus lacking tabulation and with indistinct trace of cingulum. Archeopyle formation not known. Ornament smooth to finely granulate.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt, 1978, p. 220:
Synopsis:
Cysts proximate, cornucavate or circumcavate, compressed subspherical to roundly peridinioid; pericyst usually with, rarely without, short apical and antapical horns or protrusions; paratabulation indicated by archeopyle only or by paracingulum and archeopyle; latter combination, Type "A3I3P"a.
Description:
Shape: Compressed subspherical to roundly peridinioid; pericyst usually has one short apical and two antapical horns or protrusions, less commonly one or more protrusions lacking.
Wall relationships: Cysts cornucavate to circumcavate.
Wall features: No parasutural features. Endophragm and periphragm smooth to faintly and uniformly ornamented.
Paratabulation: Expressed by archeopyle only or by archeopyle and paratabulation.
Archeopyle: Combination, Type "A3I3P"a, delimited apically and laterally by transapical suture; operculum attached antapically at paracingulum.
Paracingulum: Not indicated, or expressed faintly by low parallel, transverse, equatorial folds or linear marking on periphragm.
Parasulcus: Generally not indicated or expressed by vaguely defined depression on hypocyst.
Size: Small to intermediate.
Affinities:
Saeptodinium differs from Palaeoperidinium, which has the same archeopyle type as Saeptodinium, in lacking prominent apical and antapical horns, and in having a more rounded outline. Saeptodinium differs from Laciniadinium and Luxadinium in having a third apical paraplate involved in archeopyle formation.