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Operculodinium magnum
Operculodinium magnum sp. nov.; Vieira, M. et al. 2018
Holotype: Vieira, M. et al. 2018, Plate 3
Age: Danian
Original description: Vieira, M. et al. 2018: Operculodinium magnum sp. nov.
Description:
Proximochorate, gonyaulacoid cyst exhibiting a spherical to subspherical central body. Consist of two layers, with the periphragm and autophragm adpressed between processes and its surface between process bases is densely pitted to granulate.
Cyst wall: relatively robust and thick up to 6.5 μm
Tabulation: not clear enough to determine using an optical microscope, and only visible by the loss of archeopyle: the precingular (type P) 3′′ and the free operculum.
Processes: most are slender terminating in broad, conical bases randomly distributed across the central body. Numerous solid, fibrous, flexuous and nontabular processes which are varied in length and thickness. The shape of the distal extremities of the processes varies from one specimen to the other ranging from simple and acuminate to bifurcate or trifurcate, some processes branch at half-length to form two or more sets of tips. Process length varies between 14 and 23.5 μm on one specimen. Several specimens show a variation in width and robustness of the processes and occasionally some of the processes at the apical are joined to for a more wider process.
Dimensions:
Diameter of cyst body 73 (81) 87 μm, cyst with processes 84 (104) 122 μm, length of processes 14 (20.5) 28.5 μm
Number of specimens measured: 22.
Remarks:
Islam (1983) stated that the genus Operculodinium (Deflandre and Cookson 1955) Wall 1967 emend. Matsuoka et al.1997 possesses both fibrous and nonfibrous processes or any combination of both types, contrary to Stover and Evitt (1978).
Affinities:
This new species can be easily differentiated from other species of Operculodinium, particularly Operculodinium centrocarpum (Wall, 1967) (Pl. III, 9) which occur at the same stratigraphic interval, by its larger size and thicker wall, but also the distinctive morphology of the processes. This species is recorded from Danian sediments throughout the North Sea Basin.
Holotype: Vieira, M. et al. 2018, Plate 3
Age: Danian
Original description: Vieira, M. et al. 2018: Operculodinium magnum sp. nov.
Description:
Proximochorate, gonyaulacoid cyst exhibiting a spherical to subspherical central body. Consist of two layers, with the periphragm and autophragm adpressed between processes and its surface between process bases is densely pitted to granulate.
Cyst wall: relatively robust and thick up to 6.5 μm
Tabulation: not clear enough to determine using an optical microscope, and only visible by the loss of archeopyle: the precingular (type P) 3′′ and the free operculum.
Processes: most are slender terminating in broad, conical bases randomly distributed across the central body. Numerous solid, fibrous, flexuous and nontabular processes which are varied in length and thickness. The shape of the distal extremities of the processes varies from one specimen to the other ranging from simple and acuminate to bifurcate or trifurcate, some processes branch at half-length to form two or more sets of tips. Process length varies between 14 and 23.5 μm on one specimen. Several specimens show a variation in width and robustness of the processes and occasionally some of the processes at the apical are joined to for a more wider process.
Dimensions:
Diameter of cyst body 73 (81) 87 μm, cyst with processes 84 (104) 122 μm, length of processes 14 (20.5) 28.5 μm
Number of specimens measured: 22.
Remarks:
Islam (1983) stated that the genus Operculodinium (Deflandre and Cookson 1955) Wall 1967 emend. Matsuoka et al.1997 possesses both fibrous and nonfibrous processes or any combination of both types, contrary to Stover and Evitt (1978).
Affinities:
This new species can be easily differentiated from other species of Operculodinium, particularly Operculodinium centrocarpum (Wall, 1967) (Pl. III, 9) which occur at the same stratigraphic interval, by its larger size and thicker wall, but also the distinctive morphology of the processes. This species is recorded from Danian sediments throughout the North Sea Basin.