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Palaeoperidinium mosaicum
Palaeoperidinium "mosaicum" Downie, 1957, p.424, pl.20, fig.7; text-fig.2f. Emendation: Sarjeant, 1976c, p.6–7, as Leptodinium mosaicum.
Name not validly published: generic name not validly published until 1967.
NOW Leptodinium?. Originally Palaeoperidinium (name not validly published), subsequently Gonyaulacysta, thirdly Leptodinium, fourthly (and now) Leptodinium?.
Holotype: Downie, 1957, pl.20, fig.7; text-fig.2f; Sarjeant, 1976c, pl.2, figs.3,5; text-figs.2a–b; Jan du Chêne et al., 1986a, pl.70, figs.5–6.
Age: late Kimmeridgian.
Original diagnosis: Downie, 1957, p. 424
The ellipsoidal test is rigid and thick-walled. No process is present. The spiral equatorial furrow is central. Numerous small granular plates are present but not clearly arranged in belts. A longitudinal furrow is indicated by a belt of larger smoother plates.
Dimensions of holotype:
Length 50 µm; breadth 42 µm; depth 42 µm; thickness of wall 1 µm.
Affinities:
Downie, 1957, p. 424: This form differs considerably from any of the other dinoflagellates found, but the presence of the equatorial furrow indicates its affinity. The rigidity of the test, which is quite uncrushed, suggests that it was originally partly mineralized. Any mineral matter originally present has, however, been removed by treatment with acid. In many ways it resembles Eodinia Eisenack 1936, but since it was impossible to determine whether the original wall was silico-organic, it could not be placed with any certainty in that genus.
Name not validly published: generic name not validly published until 1967.
NOW Leptodinium?. Originally Palaeoperidinium (name not validly published), subsequently Gonyaulacysta, thirdly Leptodinium, fourthly (and now) Leptodinium?.
Holotype: Downie, 1957, pl.20, fig.7; text-fig.2f; Sarjeant, 1976c, pl.2, figs.3,5; text-figs.2a–b; Jan du Chêne et al., 1986a, pl.70, figs.5–6.
Age: late Kimmeridgian.
Original diagnosis: Downie, 1957, p. 424
The ellipsoidal test is rigid and thick-walled. No process is present. The spiral equatorial furrow is central. Numerous small granular plates are present but not clearly arranged in belts. A longitudinal furrow is indicated by a belt of larger smoother plates.
Dimensions of holotype:
Length 50 µm; breadth 42 µm; depth 42 µm; thickness of wall 1 µm.
Affinities:
Downie, 1957, p. 424: This form differs considerably from any of the other dinoflagellates found, but the presence of the equatorial furrow indicates its affinity. The rigidity of the test, which is quite uncrushed, suggests that it was originally partly mineralized. Any mineral matter originally present has, however, been removed by treatment with acid. In many ways it resembles Eodinia Eisenack 1936, but since it was impossible to determine whether the original wall was silico-organic, it could not be placed with any certainty in that genus.