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Levisphaera
From Fensome et al., 2019:
Levisphaera, Davey, 1988, p.40.
Type: Burger, 1980b, figs.4D1–2, as Canningia crassicingulata.
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Original description: [Davey, 1988]:
Diagnosis:
Shape: The body is subspherical to ovoidal in shape with minor dorso-ventral flattening and without distinct horns.
Wall: The autophragm is hyaline (unstructured) and has a smooth, unornamented surface.
Tabulation: None expressed by surface features.
Archaeopyle: Apical, Type tA, with a zigzag margin. Operculum generally free. Accessory precingular sutures may extend from the archaeopyle towards the cingulum.
Affinities:
The combination of apical archaeopyle and smooth, unstructured wall differentiates Levisphaera from all previously described dinocysts. In overall appearance it is most comparable to Chytroeisphaeridia Sarjeant 1962 emend Davey 1979 which, however, has a precingular archaeopyle.
Fromea Cookson and Eisenack is also very similar and has an apical opening which, however, has a smooth, concave margin rather than a zigzag margin. Strictly this apical opening cannot be termed an archaeopyle.
Other similar genera with apical archaeopyles are batiacasphaera Drugg 1970, Sentusidinium Sarjeant and Stover 1978 and Escharisphaeridia Erkmen and Sarjeant 1980 which have low ornamented to more or less smooth walls which are complexly structured.
Levisphaera, Davey, 1988, p.40.
Type: Burger, 1980b, figs.4D1–2, as Canningia crassicingulata.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Davey, 1988]:
Diagnosis:
Shape: The body is subspherical to ovoidal in shape with minor dorso-ventral flattening and without distinct horns.
Wall: The autophragm is hyaline (unstructured) and has a smooth, unornamented surface.
Tabulation: None expressed by surface features.
Archaeopyle: Apical, Type tA, with a zigzag margin. Operculum generally free. Accessory precingular sutures may extend from the archaeopyle towards the cingulum.
Affinities:
The combination of apical archaeopyle and smooth, unstructured wall differentiates Levisphaera from all previously described dinocysts. In overall appearance it is most comparable to Chytroeisphaeridia Sarjeant 1962 emend Davey 1979 which, however, has a precingular archaeopyle.
Fromea Cookson and Eisenack is also very similar and has an apical opening which, however, has a smooth, concave margin rather than a zigzag margin. Strictly this apical opening cannot be termed an archaeopyle.
Other similar genera with apical archaeopyles are batiacasphaera Drugg 1970, Sentusidinium Sarjeant and Stover 1978 and Escharisphaeridia Erkmen and Sarjeant 1980 which have low ornamented to more or less smooth walls which are complexly structured.