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Oligosphaeridium magnum
From Fensome et al., 2019:
Oligosphaeridium magnum Duxbury, 2019, p.197–198, pl.15, figs.1–5,8,13. Holotype: Duxbury, 2019, pl.15, fig.1. Age: late
Barremian.
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Original description Duxbury, 2019:
Plate 15, Figures 1–5, 8, 13
Holotype: Plate 15, Figure 1
Type Locality: Well 22/26a-2 at 11,179.50 ft (core chip), late Barremian age. Holotype E.F. J34.3.
Derivation of Name: From the Latin magnus, large, great, in reference to the very large size of this species.
Diagnosis: A large, thin-walled species with a smooth, spheroidal main body. Hollow, mesotabular processes of equal length but variable breadth indicate a tabulation scheme of 4', 6'', 0c, 6''', 1p, 1''''. Processes taper, being narrowest at about half their length. Distal terminations vary on individual specimens from complex margins with long fringing spines to regularly or irregularly fenestrate. Some processes bear longitudinal perforations which may penetrate the distal margin, effectively removing one side of the process. The archeopyle involves the loss of four apical plates with some additional splitting along precingular sutures.
Dimensions: Holotype - Central body - 63 × 86 μm. Overall - 134 × 139 μm
Other measured specimens: Central body - 91 (77) 63 μm × 94 (79) 63 μm.
Overall – 152 (141) 129 μm × 152 (132) 101 μm.
Specimens Measured: 10.
Remarks: The processes of this very large species vary significantly, flaring distally and showing a wide range of
morphologies on individual specimens from simple to very complex. The presence on some processes of longitudinal holes sometimes penetrating the distal margin is a similar feature to that in Perisseiasphaeridium cretaceum Duxbury 2018 and Oligosphaeridium distinctum Duxbury 2018.
Specimens tend to be randomly-oriented because of the spheroidal shape of this taxon, and there was no evidence of tabulation other than for the process distribution and archeopyle. This taxon was recorded between 11,181.33 ft and 11,173.00 ft in well 22/26a-2. It was rare except for a major influx at 11,179.50 ft; similar discrete major influxes have been observed at this level within the late Barremian elsewhere in the Central North Sea, where it is a valuable stratigraphic marker for palynofloral Subzone LKP23.1.
Oligosphaeridium magnum Duxbury, 2019, p.197–198, pl.15, figs.1–5,8,13. Holotype: Duxbury, 2019, pl.15, fig.1. Age: late
Barremian.
---------------------------------------------------------------------------------------------------
Original description Duxbury, 2019:
Plate 15, Figures 1–5, 8, 13
Holotype: Plate 15, Figure 1
Type Locality: Well 22/26a-2 at 11,179.50 ft (core chip), late Barremian age. Holotype E.F. J34.3.
Derivation of Name: From the Latin magnus, large, great, in reference to the very large size of this species.
Diagnosis: A large, thin-walled species with a smooth, spheroidal main body. Hollow, mesotabular processes of equal length but variable breadth indicate a tabulation scheme of 4', 6'', 0c, 6''', 1p, 1''''. Processes taper, being narrowest at about half their length. Distal terminations vary on individual specimens from complex margins with long fringing spines to regularly or irregularly fenestrate. Some processes bear longitudinal perforations which may penetrate the distal margin, effectively removing one side of the process. The archeopyle involves the loss of four apical plates with some additional splitting along precingular sutures.
Dimensions: Holotype - Central body - 63 × 86 μm. Overall - 134 × 139 μm
Other measured specimens: Central body - 91 (77) 63 μm × 94 (79) 63 μm.
Overall – 152 (141) 129 μm × 152 (132) 101 μm.
Specimens Measured: 10.
Remarks: The processes of this very large species vary significantly, flaring distally and showing a wide range of
morphologies on individual specimens from simple to very complex. The presence on some processes of longitudinal holes sometimes penetrating the distal margin is a similar feature to that in Perisseiasphaeridium cretaceum Duxbury 2018 and Oligosphaeridium distinctum Duxbury 2018.
Specimens tend to be randomly-oriented because of the spheroidal shape of this taxon, and there was no evidence of tabulation other than for the process distribution and archeopyle. This taxon was recorded between 11,181.33 ft and 11,173.00 ft in well 22/26a-2. It was rare except for a major influx at 11,179.50 ft; similar discrete major influxes have been observed at this level within the late Barremian elsewhere in the Central North Sea, where it is a valuable stratigraphic marker for palynofloral Subzone LKP23.1.