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Isabelidinium papillum
Isabelidinium papillum Sumner, 1992
Holotype: Sumner, 1992, fig.3b
Paratype: Sumner, 1992, fig.3c
Locus typicus: Ekel÷f Point, James Ross Island, Antarctica
Stratum typicum: latest Santonian-Late Campanian
Diagnosis: Sumner, 1992, p. 306
A bicavate, peridinacean dinoflagellate cyst, generally oval in outline with a distinct equatorial bulge and spherical to oval endocyst. The periphragm possesses a short apical protrusion. The cyst shows no paracingulum or other evidence of tabulation except a steno-deltaform intercalary periarchaeopyle, corresponding to the 2a paraplate. The periphragm is smooth to finely granulate.
Description: Sumner, 1992, p. 306
A dinoflagellate cyst species with a bicavate wall relationship and a generally oval to elongate oval outline, bulging at the equator where the endophragm and periphragm are closely appressed. The endocyst is spherical to oval in outline. The cyst has a blunt conical epicyst with a prominent, hollow apical protrusion up to 14 Ám in length. The antapex is often truncated, or less commonly shows slight development of two antapical horns, the left commonly showing stronger development. The only indication of paratabulation is the periarchaeopyle which is a single plate intercalary (type I), corresponding to the 2a paraplate, with a steno-deltaform shape. No endoarchaeopyle has been observed . The operculum is usually free. The surface of the cyst is smooth to finely granulate, many specimens posessing nontabular granular ornament towards the apex and antapex.
Affinities: Sumner, 1992, p. 306, 308
Isabelidinium papillum is similar in size and general outline to l. pellucidum and I. korojonense, but it possesses a relatively smaller endocyst than I. pellucidum and has a more rounded apex. It differs from I. korojonense by lacking the distinctive serrated shoulders and having a more elongate archaeopyle shape. It differs from all other members of the genus by the posession of a distinctive apical protrusion.
Dimensions (Ám):MinMeanMax
Overall length:5469.089
Overall breadth:3648.156
Endocyst length:2133.350
Length of apicalprotrusion23.714
Specimens measured: 30
Holotype: Sumner, 1992, fig.3b
Paratype: Sumner, 1992, fig.3c
Locus typicus: Ekel÷f Point, James Ross Island, Antarctica
Stratum typicum: latest Santonian-Late Campanian
Diagnosis: Sumner, 1992, p. 306
A bicavate, peridinacean dinoflagellate cyst, generally oval in outline with a distinct equatorial bulge and spherical to oval endocyst. The periphragm possesses a short apical protrusion. The cyst shows no paracingulum or other evidence of tabulation except a steno-deltaform intercalary periarchaeopyle, corresponding to the 2a paraplate. The periphragm is smooth to finely granulate.
Description: Sumner, 1992, p. 306
A dinoflagellate cyst species with a bicavate wall relationship and a generally oval to elongate oval outline, bulging at the equator where the endophragm and periphragm are closely appressed. The endocyst is spherical to oval in outline. The cyst has a blunt conical epicyst with a prominent, hollow apical protrusion up to 14 Ám in length. The antapex is often truncated, or less commonly shows slight development of two antapical horns, the left commonly showing stronger development. The only indication of paratabulation is the periarchaeopyle which is a single plate intercalary (type I), corresponding to the 2a paraplate, with a steno-deltaform shape. No endoarchaeopyle has been observed . The operculum is usually free. The surface of the cyst is smooth to finely granulate, many specimens posessing nontabular granular ornament towards the apex and antapex.
Affinities: Sumner, 1992, p. 306, 308
Isabelidinium papillum is similar in size and general outline to l. pellucidum and I. korojonense, but it possesses a relatively smaller endocyst than I. pellucidum and has a more rounded apex. It differs from I. korojonense by lacking the distinctive serrated shoulders and having a more elongate archaeopyle shape. It differs from all other members of the genus by the posession of a distinctive apical protrusion.
Dimensions (Ám):MinMeanMax
Overall length:5469.089
Overall breadth:3648.156
Endocyst length:2133.350
Length of apicalprotrusion23.714
Specimens measured: 30