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Leptodinium mosaicum
Leptodinium? mosaicum (Downie, 1957, p.424, pl.20, fig.7; text-fig.2f ex Sarjeant, 1967b, p.253) Sarjeant, 1969, p.13. Emendation: Sarjeant, 1976c, p.6–7, as Leptodinium mosaicum.
Originally Palaeoperidinium (name not validly published), subsequently Gonyaulacysta, thirdly Leptodinium, fourthly (and now) Leptodinium?. Questionable assignment: Stover and Evitt (1978, p.170).
The name Palaeoperidinium mosaicum was not validly published in Downie (1957) since the generic name Palaeoperidinium was not validly published until 1967. Williams et al. (1998, p.371) accepted Sarjeant's (1967b) indirect reference to Downie (1957) as indication of a type (I.C.N. Article 40.3). Jan du Chêne et al. (1986a, p.210) considered that this species may be assignable to Acanthaulax.
Holotype: Downie, 1957, pl.20, fig.7, text-fig.2f; Sarjeant, 1976, pl.2, figs.3,5, text-figs.2a-b; Jan du Chêne et al., 1986, pl.70, figs.5-6
Locus typicus: Dorset, England
Stratum typicum: Middle Kimmeridgian
Original diagnosis: Downie, 1957, p. 424: Palaeoperidinium mosaicum
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: Palaeoperidinium mosaicum
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.
Originally Palaeoperidinium (name not validly published), subsequently Gonyaulacysta, thirdly Leptodinium, fourthly (and now) Leptodinium?. Questionable assignment: Stover and Evitt (1978, p.170).
The name Palaeoperidinium mosaicum was not validly published in Downie (1957) since the generic name Palaeoperidinium was not validly published until 1967. Williams et al. (1998, p.371) accepted Sarjeant's (1967b) indirect reference to Downie (1957) as indication of a type (I.C.N. Article 40.3). Jan du Chêne et al. (1986a, p.210) considered that this species may be assignable to Acanthaulax.
Holotype: Downie, 1957, pl.20, fig.7, text-fig.2f; Sarjeant, 1976, pl.2, figs.3,5, text-figs.2a-b; Jan du Chêne et al., 1986, pl.70, figs.5-6
Locus typicus: Dorset, England
Stratum typicum: Middle Kimmeridgian
Original diagnosis: Downie, 1957, p. 424: Palaeoperidinium mosaicum
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: Palaeoperidinium mosaicum
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.