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Circulodinium copei
Circulodinium copei, Bailey et al., 1997, p.235-236, figs.3a-f.
Holotype: Bailey et al., 1997, fig.3a.
Type locality: Kimmeridge Clay Formation (Bed 12 of Cope 1974), uppermost Pectinatites heddlestoni Ammonite Zone at Golden Hill Quarry, Marton, North Yorkshire.
Age: Late Kimmeridgian.
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Original description: [Bailey et al., 1997]:
Diagnosis:
Proximate, ovoidal – subspherical, dorso-ventrally compressed dinoflagellate cyst. Apical region rounded to broadly conical.
The wall is thick (1-2 μm) and variably structured, appearing intraperforate to spongiose in transmitted light, sometimes with short spines. Paratabulation is absent, except for indication of paracingulum and parasulcus.
The apical archeopyle has a gently zigzag outline and the operculum is often attached.
Size range 50-80 μm.
Description:
Shape: ovoidal – subpolygonal, with dorsoventral compression. Apical region rounded to broadly conical.
Wall relationships: cyst proximate, acavate.
Wall features: autophragm thick, intraperforate to spongiose, occasionally with short spines. The surface of the all may appear microreticulate. Paratabulation: restricted to representation of the paracingulum and parasulcus.
Archeopyle: type tA or tAa, margin gently zigzag and generally without significant accessory archeopyle sutures. It is not certain whether specimens without opercula have lost them through mechanical or biological processes.
Dimensions:
size range 50-80 μm in length: holotype length: 70 μm, width: 75 μm.
Affinities:
Circulodinium copei is most similar to C. comptum (Davey, 1982) Helby 1987. It differs in having a thicker, more complexity structured autophragm and usually has a less zigzagged archeopyle margin.
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Occurrence:
Recorded from the Pectinatites pectinatus and Pectinatites hudlestoni zones in this study. In samples M6, M9 and M10, C. copei is common or abundant. The species had also been recorded (as Chytroeisphaeridia mantellii) in small numbers from the Pectinatites wheatleyensis Zone in Dordet, southern England (Ioannides et al., 1977). The total recorded range of this speciesis therefore late Kimmeridgian, Pectinatites wheatleyensis to Pectinatites pectinatus zones.
Holotype: Bailey et al., 1997, fig.3a.
Type locality: Kimmeridge Clay Formation (Bed 12 of Cope 1974), uppermost Pectinatites heddlestoni Ammonite Zone at Golden Hill Quarry, Marton, North Yorkshire.
Age: Late Kimmeridgian.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Bailey et al., 1997]:
Diagnosis:
Proximate, ovoidal – subspherical, dorso-ventrally compressed dinoflagellate cyst. Apical region rounded to broadly conical.
The wall is thick (1-2 μm) and variably structured, appearing intraperforate to spongiose in transmitted light, sometimes with short spines. Paratabulation is absent, except for indication of paracingulum and parasulcus.
The apical archeopyle has a gently zigzag outline and the operculum is often attached.
Size range 50-80 μm.
Description:
Shape: ovoidal – subpolygonal, with dorsoventral compression. Apical region rounded to broadly conical.
Wall relationships: cyst proximate, acavate.
Wall features: autophragm thick, intraperforate to spongiose, occasionally with short spines. The surface of the all may appear microreticulate. Paratabulation: restricted to representation of the paracingulum and parasulcus.
Archeopyle: type tA or tAa, margin gently zigzag and generally without significant accessory archeopyle sutures. It is not certain whether specimens without opercula have lost them through mechanical or biological processes.
Dimensions:
size range 50-80 μm in length: holotype length: 70 μm, width: 75 μm.
Affinities:
Circulodinium copei is most similar to C. comptum (Davey, 1982) Helby 1987. It differs in having a thicker, more complexity structured autophragm and usually has a less zigzagged archeopyle margin.
----------------------------------------------------------------------------------------------
Occurrence:
Recorded from the Pectinatites pectinatus and Pectinatites hudlestoni zones in this study. In samples M6, M9 and M10, C. copei is common or abundant. The species had also been recorded (as Chytroeisphaeridia mantellii) in small numbers from the Pectinatites wheatleyensis Zone in Dordet, southern England (Ioannides et al., 1977). The total recorded range of this speciesis therefore late Kimmeridgian, Pectinatites wheatleyensis to Pectinatites pectinatus zones.