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Uvatodinium
From Williams et al., 2017:
[Uvatodinium Vozzhennikova, 1963, p. 182; Emendation: Lentin and Vozzhennikova, 1990, p. 70.
Type species: as Uvatodinium nasutum, Vozzhennikova, 1963 (text-figs.13a-b) (which see for lectotype)]
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Original description: [Vozzhennikova, 1963]: (Translation Vozzhennikova, 1963: Stover and Evitt, 1978, p. 128):
Description:
Cells spherical or subovoidal with a sharply projecting anterior or apical horn. Posterior or antapical horns absent; instead, ridge-like or other types of structures are developed along the hypovalve. Transverse furrow circular, located at the middle of the cell or somewhat lower in the latter case dividing the cell into two unequal parts. Longitudinal furrow begins at the transverse furrow and is confined to the hypovalve. Test hyaline, dense, with a cell-like pattern. In places short projections or spinules may occur along the ridges of the cells.
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Modified description:
Stover and Evitt, 1978, p. 128:
Synopsis:
Cysts proximate, compressed subspherical, with a short apical horn or protrusion and without antapical horns or protrusions; wall layers, normally appressed over most of cyst, are apically cornucavate; surface has nontabular features of low to moderate relief; paratabulation typically indicated by archeopyle only; archeopyle intercalary, Type I or la.
Description:
Shape: Compressed subspherical, with short apical horn or protrusion.
Wall Relationships: Endophragm and periphragm compressed over most of cyst; apically cornucavate and wall layers may be slightly separated antapically.
Wall Features: Surface may be reticulate, or granulate or echinate; reticulum may bear spines at intersection of muri.
Paratabulation: Indicated by archeopyle only.
Archeopyle: Intercalary, Type I or la (2a only).
Paracingulum: Vaguely indicated; usually discernible only at lateral margins.
Parasulcus: Vaguely indicated; appears to be wider on hypocyst than on epicyst.
Size: Intermediate to large.
Affinities:
Uvatodinium differs from Apteodinium in having an intercalary rather than a precingular archeopyle. Evidently the only difference between Uvatodinium and Vozzhennikovia is that the latter has a distinct left antapical horn, which Uvatodinium lacks.
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Emended description:
Lentin and Vozzhennikova, 1990:
Description:
Fossil dinoflagellate cyst shape oval with a single long, narrow, distally rounded apical horn; periphragm may expand in area of paracingulum to provide short lateral extensions; hypocyst broadly rounded, without antapical horns; endophragm oval, may be closely appressed to periphragm on the epicyst except in the area of the apical horn and paracingulum, endophragm and periphragm more or less separate on hypocyst; cornucavate to circumcavate.
Periphragm ornamented with randomly distributed fine to coarse reticulum, small coni may arise at the junctions of the reticulum; endophragm smooth to finely granulose.
Paratabulation indicated by archeopyle and paracingulum only; peridinioid.
Archeopyle identical in both wall layers, small standard hexa formed by the loss of the 2a intercalary paraplate, operculum free.
Paracingulum indicated by a shallow depression at the lateral margins. Parasulcus not indicated or indicated by a shallow depression only.
Affinities: (p. 71):
The genus Uvatotinium is emended to describe the nature of the archeopyle, relationship of the wall layers and the style of ornament. There are currently only two species in this genus, the holotype Uvatotinium nasutum (with U. marginatum Vozzhennikova, 1967 as a junior synonym) and U. minutum Mao Shaozhi, 1988. The latter species is small (58-64 μm) and is ornamented with numerous, small non-tabular spines and is without indication of a reticulum. It is here considered to be Vozzhennikovia which differs from Uvatotinium in its small size and the nature of the nontabular, spinose ornament.
[Uvatodinium Vozzhennikova, 1963, p. 182; Emendation: Lentin and Vozzhennikova, 1990, p. 70.
Type species: as Uvatodinium nasutum, Vozzhennikova, 1963 (text-figs.13a-b) (which see for lectotype)]
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Original description: [Vozzhennikova, 1963]: (Translation Vozzhennikova, 1963: Stover and Evitt, 1978, p. 128):
Description:
Cells spherical or subovoidal with a sharply projecting anterior or apical horn. Posterior or antapical horns absent; instead, ridge-like or other types of structures are developed along the hypovalve. Transverse furrow circular, located at the middle of the cell or somewhat lower in the latter case dividing the cell into two unequal parts. Longitudinal furrow begins at the transverse furrow and is confined to the hypovalve. Test hyaline, dense, with a cell-like pattern. In places short projections or spinules may occur along the ridges of the cells.
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Modified description:
Stover and Evitt, 1978, p. 128:
Synopsis:
Cysts proximate, compressed subspherical, with a short apical horn or protrusion and without antapical horns or protrusions; wall layers, normally appressed over most of cyst, are apically cornucavate; surface has nontabular features of low to moderate relief; paratabulation typically indicated by archeopyle only; archeopyle intercalary, Type I or la.
Description:
Shape: Compressed subspherical, with short apical horn or protrusion.
Wall Relationships: Endophragm and periphragm compressed over most of cyst; apically cornucavate and wall layers may be slightly separated antapically.
Wall Features: Surface may be reticulate, or granulate or echinate; reticulum may bear spines at intersection of muri.
Paratabulation: Indicated by archeopyle only.
Archeopyle: Intercalary, Type I or la (2a only).
Paracingulum: Vaguely indicated; usually discernible only at lateral margins.
Parasulcus: Vaguely indicated; appears to be wider on hypocyst than on epicyst.
Size: Intermediate to large.
Affinities:
Uvatodinium differs from Apteodinium in having an intercalary rather than a precingular archeopyle. Evidently the only difference between Uvatodinium and Vozzhennikovia is that the latter has a distinct left antapical horn, which Uvatodinium lacks.
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Emended description:
Lentin and Vozzhennikova, 1990:
Description:
Fossil dinoflagellate cyst shape oval with a single long, narrow, distally rounded apical horn; periphragm may expand in area of paracingulum to provide short lateral extensions; hypocyst broadly rounded, without antapical horns; endophragm oval, may be closely appressed to periphragm on the epicyst except in the area of the apical horn and paracingulum, endophragm and periphragm more or less separate on hypocyst; cornucavate to circumcavate.
Periphragm ornamented with randomly distributed fine to coarse reticulum, small coni may arise at the junctions of the reticulum; endophragm smooth to finely granulose.
Paratabulation indicated by archeopyle and paracingulum only; peridinioid.
Archeopyle identical in both wall layers, small standard hexa formed by the loss of the 2a intercalary paraplate, operculum free.
Paracingulum indicated by a shallow depression at the lateral margins. Parasulcus not indicated or indicated by a shallow depression only.
Affinities: (p. 71):
The genus Uvatotinium is emended to describe the nature of the archeopyle, relationship of the wall layers and the style of ornament. There are currently only two species in this genus, the holotype Uvatotinium nasutum (with U. marginatum Vozzhennikova, 1967 as a junior synonym) and U. minutum Mao Shaozhi, 1988. The latter species is small (58-64 μm) and is ornamented with numerous, small non-tabular spines and is without indication of a reticulum. It is here considered to be Vozzhennikovia which differs from Uvatotinium in its small size and the nature of the nontabular, spinose ornament.