Dioxia apertura (Wilson, 1967) Morgan, 1977

Now Vozzhennikovia. Originally Spinidinium, subsequently (and now) Vozzhennikouia, thirdly Dioxya.
Lentin and Williams, 1981, retained this species in Vozzhennikouia Lentin and Williams, 1976.
Holotype: Wilson, 1967, figs.3-4
Paratype: Wilson, 1967
Locus typicus: Erratics on Black Island, McMurdo Sound, Antarctica
Stratum typicum: Paleocene-Oligocene

Original description: Wilson, 1967, p.64-65: Spinidinium apertura
Test broadly rounded to sub-angular, differentiated into two closely joined layers forming inner and outer cysts. Surface of outer cyst thickly covered with pointed or flat-tipped spines, evenly distributed over the dorsal and ventral surfaces except on transverse girdle and longitudinal furrow. Transverse girdle wide, deeply grooved, either non-spiral or very slightly laevo-rotatory, delimited by two parallel rows of closely spaced spines. Longitudinal furrow a very prominent deep groove devoid of spines. Apical horn relatively long (I = 8-10 Ám) rectangular and usually terminated by either one or two small spines; right antapical horn short (I = 2-3 Ám) pointed; left antapical horn absent but position defined by slight angularity in shell outline. Archeopyle very prominent, intercalary, hexagonal, located on dorsal epitheca. Operculum free, distinctive, often occurs totally separated from parent shell ([Wilson, 1967] Fig. 8). Atabulate.
Size: Holotype: length 52 Ám, breadth 44 Ám. Range of 7 specimens: length 47(53)58 Ám, breadth 41(45)47 Ám.