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Heibergella
From Williams et al., 2017:
[Heibergella, Bujak and Fisher, 1976, p. 52, 54
Type species: Heibergella asymmetrica, Bujak and Fisher, 1976 (pl.8, figs.1–2)]
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Original description: [Bujak and Fisher, 1976]:
Description:
Apparently single-walled dinoflagellate cysts without reflected tabulation. One apical and one or two antapical horns present or absent. Cingulum and sulcus well or poorly defined. Outer surface of periphragm smooth, scabrate, granular, or spinose. Archeopyle anterior intercalary, formed by loss or displacement of one to three plates.
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Modified description:
Stover and Evitt, 1978, p. 107:
Synopsis:
Cysts proximate, compressed, subspherical to nearly biconical, with or without one apical and one or two antapical horns; autophragm smooth to variously ornamented with nontabular features of low to moderate relief; paratabulation indicated by archeopyle only, or by paracingulum and archeopyle; latter intercalary, Types I or 2I and 3I.
Description:
Shape: Compressed, subspherical to nearly biconical; one apical and one or two antapical horns or protrusions may be present; second antapical horn rarely developed.
Wall relationships: Autophragm only.
Wall features: Autophragm smooth, scabrate, granulate, or spinate; ornamentation usually distributed more or less uniformly, but may be
arranged locally in rows.
Paratabulation: Indicated by archeopyle only, or by archeopyle and paracingulum.
Archeopyle: Intercalary, Types I or 2I and 3I, operculum free or displaced; individual species with either Type I only, or with Type 2I and 3I archeopyles.
Paracingulum: Poorly to clearly delimited by transverse parallel equatorial folds, ridges, or rows of spines or granules.
Parasulcus: Expressed mainly on hypocyst by features like those delimiting the parasulcus.
Size: Intermediate.
Affinities:
Heibergella differs from Rhaetogonyaulax in having an intercalary rather than a combination archeopyle and in lacking indications of paratabulation other than the archeopyle and paracingulum.
[Heibergella, Bujak and Fisher, 1976, p. 52, 54
Type species: Heibergella asymmetrica, Bujak and Fisher, 1976 (pl.8, figs.1–2)]
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Original description: [Bujak and Fisher, 1976]:
Description:
Apparently single-walled dinoflagellate cysts without reflected tabulation. One apical and one or two antapical horns present or absent. Cingulum and sulcus well or poorly defined. Outer surface of periphragm smooth, scabrate, granular, or spinose. Archeopyle anterior intercalary, formed by loss or displacement of one to three plates.
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Modified description:
Stover and Evitt, 1978, p. 107:
Synopsis:
Cysts proximate, compressed, subspherical to nearly biconical, with or without one apical and one or two antapical horns; autophragm smooth to variously ornamented with nontabular features of low to moderate relief; paratabulation indicated by archeopyle only, or by paracingulum and archeopyle; latter intercalary, Types I or 2I and 3I.
Description:
Shape: Compressed, subspherical to nearly biconical; one apical and one or two antapical horns or protrusions may be present; second antapical horn rarely developed.
Wall relationships: Autophragm only.
Wall features: Autophragm smooth, scabrate, granulate, or spinate; ornamentation usually distributed more or less uniformly, but may be
arranged locally in rows.
Paratabulation: Indicated by archeopyle only, or by archeopyle and paracingulum.
Archeopyle: Intercalary, Types I or 2I and 3I, operculum free or displaced; individual species with either Type I only, or with Type 2I and 3I archeopyles.
Paracingulum: Poorly to clearly delimited by transverse parallel equatorial folds, ridges, or rows of spines or granules.
Parasulcus: Expressed mainly on hypocyst by features like those delimiting the parasulcus.
Size: Intermediate.
Affinities:
Heibergella differs from Rhaetogonyaulax in having an intercalary rather than a combination archeopyle and in lacking indications of paratabulation other than the archeopyle and paracingulum.