Gonyaulacysta hyaloderma

"?hyaloderma" Deflandre, 1939b, p.144, pl.6, figs.3-4 ex Sarjeant, 1967b, p.252.  Holotype: Deflandre, 1939b, pl.6, figs.3-4; Jan du Chêne et al., 1986a, pl.58, figs.1-5.  NOW Impagidinium?.  Originally Palaeoperidinium (name not validly published), subsequently Gonyaulacysta, thirdly Gonyaulacysta?, fourthly Rhynchodiniopsis?, fifthly (and now) Impagidinium?.  Questionable assignment: Stover and Evitt (1978, p.158) as a problematic species.  The name Palaeoperidinium hyalodermum was not validly published in Deflandre (1939b) since the generic name Palaeoperidinium was not validly published until 1967.  Williams et al. (1998, p.251) accepted Sarjeant's (1967b) indirect reference to Deflandre (1939b) as indication of a type (I.C.B.N. Article 37.1).  Age: Kimmeridgian.

Parent: Gonyaulacysta