Apectodinium geometricum

geometricum (Pastiels, 1948, p.41, pl.4, figs.1–11 ex Downie and Sarjeant, 1965, p.90) Fensome et al., 1990, p.617.  Holotype: Pastiels, 1948, pl.4, fig.4.  Originally Hystrichosphaeridium geometricum (name illegitimate), subsequently Baltisphaeridium geometricum (Appendix A), thirdly Apectodinium pastielsii (name illegitimate), fourthly Apectodinium geometricum.  Nomenclatural junior synonym: Apectodinium pastielsii, which has the same type.  Taxonomic junior synonym (at specific rank): Wetzeliella homomorpha var. quinquelata (as Wetzeliella quinquelata, now Apectodinium quinquelatum), by implication in Harland (1979c, p.67), who considered the latter to be the senior name — however, Lentin and Williams (1989, p.18) retained Apectodinium quinquelatum.  The name Hystrichosphaeridium geometricum Pastiels is an illegitimate junior homonym of Hystrichosphaeridium geometricum Deflandre, 1945a.  By "transferring" Pastiels' species to Baltisphaeridium, Downie and Sarjeant (1965, p.90) created the valid and legitimate name Baltisphaeridium geometricum Pastiels, 1948 ex Downie and Sarjeant, 1965.  The name Apectodinium pastielsii Lentin and Williams, 1989, is thus superfluous.  Deflandre and Cookson (1955, p.254) identified the specimen illustrated in Pastiels (1948, pl.4, fig.8) as Wetzeliella (now Apectodinium) homomorpha.  Age: Ypresian.

Parent: Apectodinium