Tectatodinium psilatum Wall and Dale in Wall et al., 1973

NOW Pyxidinopsis. Originally Tectatodinium, subsequently (and now) Pyxidinopsis.

Holotype: Wall et al., 1973, pl.1, fig.9; Head, 1994b, pl.5, figs.8–10.
Locus typicus: Black Sea, core 1451 G, 66. 5 cm
Stratum typicum: Late Quaternary

Original diagnosis: Wall and Dale, 1973, p.22
Thin-walled dinoflagellate cysts with a spherical, oval, rhombic or cruciform body outline, a simple mid-dorsal precingular archeopyle with 3" equivalence, and a psilate, minutely punctate or finely scabrate wall surface. There are no grooves that might represent either a cingulum or a longitudinal sulcus, nor are there polar horns, but a small apical boss is often present. The cyst wall is singlelayered, homogeneous, thin and predominantly smooth. It virtually lacks any projections. Some submicron-sized features are distinguishable at very high magnifications with phase-contrast optical microscopy and with the scanning electron microscope. These include minute cavities (pits, punctae) in the walls of most specimens and a distinctive scabrate fabric or irregular ridges, rods and granules in others.
Dimensions: Spherical specimens, diameters 37 - 52 µm cruciform specimens, lengths 46 - 65 µm, breadths 37 - 50 µm.