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Bitectatodinium
From Williams et al., 2017:
[Bitectatodinium, Wilson, 1973, p. 351
Type species: Bitectatodinium tepikiense, Wilson, 1973 (fig.2, nos.1–4)]
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Original description: [Wilson, 1973]:
Diagnosis: Spherical or ovoidal dinoflagellate cysts without obvious surface projections. Archeopyle formed by loss of two adjacent precingular plates. Cyst wall two-layered with a dense thin inner layer and tectate spongy outer layer. Cingulum absent or indistinct. Tabulation absent.
Affinities:
Bitectatodinium differs from Tectatodinium Wall 1967 in having a two-plate archeopyle (type 2P of Evitt 1967). In the type species the opercula comprise two free plates, which are probably reflected plates 2`` and 3``.
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Modified description:
Stover and Williams 1987, p. 41:
Synopsis:
Cysts proximate, subspherical, wall layers appressed; endophragm thin, periphragm thick, fibroid; paratabulation generally indicated by the precingular, type 2P archeopyle only, operculum free.
Description:
Shape: Subspherical
Wall relationships: Endophragm and periphragm appressed.
Wall features: Endophragm thin, periphragm thick, fibroid; outer surface finely ornamented.
Archeopyle: Precingular, type 2P (2`` + 3``); operculum free.
Paratabulation: Generally indicated by archeopyle only, occasionally also by paracingulum.
Paracingulum: Occasionally indicated by shallow, equatorial depression, or not indicated.
Parasulcus: Not indicated.
Size: Small to intermediate, about 45 μm to 60 μm in diameter.
Affinities:
Bitectatodinium differs from Tectatodinium Wall 1967 in having a 2P, rather than a simple type P, precingular archeopyle.
Lagenorhytis Duxbury 1979, which also has a precingular 2P archeopyle, has a relatively thin autophragm and an apical horn.
[Bitectatodinium, Wilson, 1973, p. 351
Type species: Bitectatodinium tepikiense, Wilson, 1973 (fig.2, nos.1–4)]
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Original description: [Wilson, 1973]:
Diagnosis: Spherical or ovoidal dinoflagellate cysts without obvious surface projections. Archeopyle formed by loss of two adjacent precingular plates. Cyst wall two-layered with a dense thin inner layer and tectate spongy outer layer. Cingulum absent or indistinct. Tabulation absent.
Affinities:
Bitectatodinium differs from Tectatodinium Wall 1967 in having a two-plate archeopyle (type 2P of Evitt 1967). In the type species the opercula comprise two free plates, which are probably reflected plates 2`` and 3``.
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Modified description:
Stover and Williams 1987, p. 41:
Synopsis:
Cysts proximate, subspherical, wall layers appressed; endophragm thin, periphragm thick, fibroid; paratabulation generally indicated by the precingular, type 2P archeopyle only, operculum free.
Description:
Shape: Subspherical
Wall relationships: Endophragm and periphragm appressed.
Wall features: Endophragm thin, periphragm thick, fibroid; outer surface finely ornamented.
Archeopyle: Precingular, type 2P (2`` + 3``); operculum free.
Paratabulation: Generally indicated by archeopyle only, occasionally also by paracingulum.
Paracingulum: Occasionally indicated by shallow, equatorial depression, or not indicated.
Parasulcus: Not indicated.
Size: Small to intermediate, about 45 μm to 60 μm in diameter.
Affinities:
Bitectatodinium differs from Tectatodinium Wall 1967 in having a 2P, rather than a simple type P, precingular archeopyle.
Lagenorhytis Duxbury 1979, which also has a precingular 2P archeopyle, has a relatively thin autophragm and an apical horn.