Back
Tapeinosphaeridium granulatum
Tapeinosphaeridium granulatum Ioannides et al., 1977
Now Pyxidinopsis. Originally Tapeinosphaeridium, subsequently Tectatodinium?, thirdly (and now) Pyxidinopsis. Questionable assignment: Davey (1979d, p.217).
Holotype: Ioannides et al., 1977, pl.4, fig.18
Locus typicus: Clavell"s Hard, Dorset, England
Stratum typicum: Kimmeridgian
Original diagnosis: Ioannides et al., 1977, p. 462
Shell spherical to ovoidal, thin-walled; surface finely to coarsely granular. Sutures may be weakly marked giving possible indication of tabulation but not determined. Cingulum sometimes poorly suggested; sulcus not observed. A precingular archaeopyle infrequently present.
Original description: Ioannides et al., 1977, p. 462
Shell surface covered with dense grana but without any form of projections. Occasionally, extremely faint sutures may simulate a plate pattern but tabulation is never determined. Cingulum may sometimes be poorly indicated by reduction of grana or arrangement of folds along a median zone. A polygonal to subcircular precingular archaeopyle is infrequently formed by loss of one plate. Secondary folds running on or parallel to periphery always present.
Dimensions. Range: shell length 48-73 µm; breadth 46-72 µm (15 specimens measured).
Affinities:
Ioannides et al., 1977, p. 462: Tapeinosphaeridium granulatum differs from T. pericompsum loannides, Stavrinos, and Downie, in the presence of grana. Chytroeisphaeridia pocockii Sarjeant, 1968, has an apical archaeopyle. Operculodinium psilatum Wall, 1967, and Tectatodinium pellitum Wall, 1967, possess two-layered shell walls, and the former is also ornamented with spiny processes.
Now Pyxidinopsis. Originally Tapeinosphaeridium, subsequently Tectatodinium?, thirdly (and now) Pyxidinopsis. Questionable assignment: Davey (1979d, p.217).
Holotype: Ioannides et al., 1977, pl.4, fig.18
Locus typicus: Clavell"s Hard, Dorset, England
Stratum typicum: Kimmeridgian
Original diagnosis: Ioannides et al., 1977, p. 462
Shell spherical to ovoidal, thin-walled; surface finely to coarsely granular. Sutures may be weakly marked giving possible indication of tabulation but not determined. Cingulum sometimes poorly suggested; sulcus not observed. A precingular archaeopyle infrequently present.
Original description: Ioannides et al., 1977, p. 462
Shell surface covered with dense grana but without any form of projections. Occasionally, extremely faint sutures may simulate a plate pattern but tabulation is never determined. Cingulum may sometimes be poorly indicated by reduction of grana or arrangement of folds along a median zone. A polygonal to subcircular precingular archaeopyle is infrequently formed by loss of one plate. Secondary folds running on or parallel to periphery always present.
Dimensions. Range: shell length 48-73 µm; breadth 46-72 µm (15 specimens measured).
Affinities:
Ioannides et al., 1977, p. 462: Tapeinosphaeridium granulatum differs from T. pericompsum loannides, Stavrinos, and Downie, in the presence of grana. Chytroeisphaeridia pocockii Sarjeant, 1968, has an apical archaeopyle. Operculodinium psilatum Wall, 1967, and Tectatodinium pellitum Wall, 1967, possess two-layered shell walls, and the former is also ornamented with spiny processes.