Spiniferites? pterotus (Cookson and Eisenack, 1958, p.50, pl.11, fig.7) Sarjeant, 1970, p.76. Emendation: Pavlishina, 1990, p.95, as Pterodinium? pterotum.

NOW Pterodinium? Originally Cymatiosphaera (acritarch), subsequently Spiniferites, thirdly Hystrichosphaera, fourthly Spiniferites?, fifthly (and now) Pterodinium?. Questionable assignment: Stover and Evitt (1978, p.191).
Taxonomic senior synonym: Cymatiosphaera (as and now Pterodinium) cingulata, according to Below (1981a, p.114) — however, Pavlishina (1990, p.95) retained Cymatiosphaera (now Pterodinium?) pterota.
Taxonomic junior synonyms: Hystrichosphaera (as Spiniferites) crassimurata, according to Kjellström (1973, p.44) and Pavlishina (1990, p.95); (at specific rank) Hystrichosphaera cingulata var. polygonalis, according to Pavlishina (1990, p.95) — however, Paul et al. (1994, p.722) retained Hystrichosphaera cingulata subsp. polygonalis (as Pterodinium cingulatum subsp. polygonale).

Holotype: Cookson and Eisenack, 1958, pl.11, fig.7
Locus typicus: W. A., Gingin area, Seismic shot hole B 2, at 230 ft.
Stratum typicum: Albian-Maastrichtian

Original diagnosis: Cookson and Eisenack, 1958, p.50: Cymatiosphaera pterota
Shell spherical, smooth, its surface divided into large fields by thin, smooth, relatively high membranes perpendicular to the surface. The margins of the membranes are frequently concave and sometimes minutely serrated.
Dimensions: Type - Overall diameter 66 µm shell 43 µm; overall range 52-85 µm. Ratio of overall diameter to shell 1.4-1.5.

Supplemental diagnosis: Davey and Williams, 1966, p.39
A species of Hystrichosphaera with well developed crests. Gonal processes reduced to supports for crests. Periphragm of each reflected plate area smooth and extremely thickened. Reflected tabulation typical for genus.
Dimensions: diameter of shell 36-46 µm, height of crests up to 14 µm.