From Fensome et al., 2019:
Impletosphaeridium varispinosum (Sarjeant, 1959, p.338–340, pl.13, fig.7; text-fig.6) Islam, 1993, p.87. Holotype: Sarjeant, 1959, pl.13, fig.7; text-fig.6; Fauconnier and Masure, 2004, pl.49, fig.8. Originally Baltisphaeridium (Appendix A), subsequently Tenua Eisenack, thirdly Sentusidinium, fourthly Sentusidinium?, fifthly Cleistosphaeridium, sixthly (and now) Impletosphaeridium. Age: early Callovian.

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Original description Sarjeant, 1959:


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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999

Impletosphaeridium varispinosum (Sarjeant, 1959) Woollam and Riding, 1983, has a dense covering of slender processes, sometimes simple, sometimes knobbed, sometimes bifurcate with very short branches. Length of processes equal to about half central body radius. Size: Holotype diameter of central body 48 µm, overall diameter 70 µm, length of processes about 10 µm.
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