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Glaphyrocysta radiata
Glaphyrocysta radiata Levy and Harwood, 2000, p.230–231, pl.5, figs.e–h.
Holotype: Levy and Harwood, 2000, pl.5, fig.e.
Age: middle-late Eocene.
Original description (Levy and Harwood, 2000):
Glaphyrocysta radiata n. sp. Plate 5, figs. e-h
Derivation of name. Latin, radiatus, in reference to the radial nature of the solid precingular intratabular processes.
Holotype. Plate 5, Figure e. UNSM PB99-01: Sample MTD 153(1), slide 2, middle to upper Eocene erratic, McMurdo Sound, Antarctica.
Description. Shape: A skolochordate dinoflagellate cyst with a subspherical central body. Solid intratabular processes and process complexes are joined distally by a fenestrate ectophragm. Processes are not present in the paracingular region. Phragma: The autophragm is shagreenate to granular. Solid, fibrous, intratabular processes extend from the autophragm and are joined distally by a fenestrate ectophragm which surrounds the lateral margin of the cyst but is absent from both the mid ventral and mid dorsal regions Paratabulation: The precingular paraplates are clearly indicated by 6 intratabular processes. Hypocystal plate arrangement is difficult to determine due to the occurrence of several accessory processes and occasional process complexes. Paracingulum: Indicated by the absence of processes in the paracingularegion of the cyst. Parasulcus: Not clearly indicated. Archeopyle: Forms by complete detachment of the apical plates
Dimensions. Observed range (four specimens): Central body length - 51 to 53 µm (mean 52 µm), central body width - 46 to 62 µm (mean 55 µm); total length - 88 to 104 µm (mean 95 µm), total width - 83 to 117 µm (mean 100 µm).
Comments. The presence of intratabular pre-cingular processes perhaps indicates an affinity to Eatonicysta Stover and Evitt (1978). However, where Eatonicysta is characterized by a complete ectophragm and the presence of paracingular processes, the ventral and dorsal regions of the specimens from the McMurdo Erratics possess neither processes nor an ectophragm. Furthermore the form described here has on offset sulcal notch. In this respect the McMurdo Erratic material fits within the generic description for Glaphyrocysta. G. radiata differs from G. semirecta (Bujak in Bujak et al., 1980) by having simple solid processes projecting from each of the precingular paraplates and by an absence of a fenestrate ectophram in both the mid-dorsal and mid-ventral region.
Stratigraphic Occurrence. Middle to upper Eocene erratics, McMurdo Sound, Antarctica.
Holotype: Levy and Harwood, 2000, pl.5, fig.e.
Age: middle-late Eocene.
Original description (Levy and Harwood, 2000):
Glaphyrocysta radiata n. sp. Plate 5, figs. e-h
Derivation of name. Latin, radiatus, in reference to the radial nature of the solid precingular intratabular processes.
Holotype. Plate 5, Figure e. UNSM PB99-01: Sample MTD 153(1), slide 2, middle to upper Eocene erratic, McMurdo Sound, Antarctica.
Description. Shape: A skolochordate dinoflagellate cyst with a subspherical central body. Solid intratabular processes and process complexes are joined distally by a fenestrate ectophragm. Processes are not present in the paracingular region. Phragma: The autophragm is shagreenate to granular. Solid, fibrous, intratabular processes extend from the autophragm and are joined distally by a fenestrate ectophragm which surrounds the lateral margin of the cyst but is absent from both the mid ventral and mid dorsal regions Paratabulation: The precingular paraplates are clearly indicated by 6 intratabular processes. Hypocystal plate arrangement is difficult to determine due to the occurrence of several accessory processes and occasional process complexes. Paracingulum: Indicated by the absence of processes in the paracingularegion of the cyst. Parasulcus: Not clearly indicated. Archeopyle: Forms by complete detachment of the apical plates
Dimensions. Observed range (four specimens): Central body length - 51 to 53 µm (mean 52 µm), central body width - 46 to 62 µm (mean 55 µm); total length - 88 to 104 µm (mean 95 µm), total width - 83 to 117 µm (mean 100 µm).
Comments. The presence of intratabular pre-cingular processes perhaps indicates an affinity to Eatonicysta Stover and Evitt (1978). However, where Eatonicysta is characterized by a complete ectophragm and the presence of paracingular processes, the ventral and dorsal regions of the specimens from the McMurdo Erratics possess neither processes nor an ectophragm. Furthermore the form described here has on offset sulcal notch. In this respect the McMurdo Erratic material fits within the generic description for Glaphyrocysta. G. radiata differs from G. semirecta (Bujak in Bujak et al., 1980) by having simple solid processes projecting from each of the precingular paraplates and by an absence of a fenestrate ectophram in both the mid-dorsal and mid-ventral region.
Stratigraphic Occurrence. Middle to upper Eocene erratics, McMurdo Sound, Antarctica.