Cordosphaeridium microtriainum

"?microtriainum" (Klumpp, 1953, p.390, pl.17, figs.6–7) Eisenack 1963b, p.263.  Emendation: Sarjeant, 1981, p.110–112, as Achomosphaera microtriaina.  Holotype: Klumpp, 1953, pl.17, figs.6–7; Sarjeant, 1981, pl.2, figs.1–2; text-fig.2.  NOW Operculodinium.  Originally Hystrichosphaeridium, subsequently Cordosphaeridium, thirdly Cordosphaeridium?, fourthly Polysphaeridium, fifthly Achomosphaera, sixthly (and now) Operculodinium.  Questionable assignment: Stover and Evitt (1978, p.147) as a problematic species.  Age: late Eocene.

Parent: Cordosphaeridium

Infrataxon List:

"Cordosphaeridium microtriainum subsp. centrocarpum"
"Cordosphaeridium microtriainum subsp. microtriainum"
"Cordosphaeridium microtriainum subsp. nanus"
"Cordosphaeridium microtriainum var. microtriainum"
"Cordosphaeridium microtriainum var. nanus"