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Gonyaulacysta diutina
Gonyaulacysta diutina Duxbury, 1977, p.34-35
NOW Wrevittia?. Originally Gonyaulacysta, subsequently Millioudodinium?, thirdly (and now) Wrevittia?.
Taxonomic senior synonym: Gonyaulax (as Gonyaulacysta, now Wrevittia) helicoidea, according to Stover and Helby (1987d, p.287) — however, Jan du Chêne et al. (1986a, p.130) and Lentin and Williams (1989, p.152) retained Gonyaulacysta (now Wrevittia?) diutina.
Holotype: Duxbury, 1977, pl.1, fig.3; text-fig.9; Jan du Chene et al., 1986, pl.41, figs.3-4
Paratype: Duxbury, 1977, pl.1, fig.5
Locus typicus: Speeton Clay, Speeton, England
Stratum typicum: Berriasian-Hauterivian
Original diagnosis: Duxbury 1977, p. 34-35
A small, proximate cyst. Endophragm ellipsoidal, longer than broad, finely granular with a random scatter of small tubercles. Periphragm smooth to finely granular, produced into fairly low sutural crests which are distally denticulate and which outline a tabulation 4", 6"", 6c, ?6""", 1p, 1"""". Apically, the periphragm is produced into a low horn which is bluntly rounded.
Dimensions: Overall 62-68x49-59 µm.
Affinities:
Duxbury 1977, p. 34-35: Gonyaulacysta diutina may be most closely compared with G.helicoidea (Eisenack and Cookson) Sarjeant as illustrated in Sarjeant 1966, but differs in several respects. G.diutina is more elongate and generally larger. The cyst body of G.helicoidea is usually polygonal with a relatively large, flat plate 1"""" whereas that of G.diutina is ellipsoidal with a distinctly convex plate 1"""". The apical horn of G.helicoidea is the most elongate with usually straight to concave sides as opposed to the bluntly rounded horn of G.diutina. Sometimes there is a small pericoel at the base of the horn in G.diutina. Most observed specimens of G.diutina had a lateral orientation suggesting some inherent lateral flattening. All specimens of G.diutina were seen to have a dorso-ventral compression.
NOW Wrevittia?. Originally Gonyaulacysta, subsequently Millioudodinium?, thirdly (and now) Wrevittia?.
Taxonomic senior synonym: Gonyaulax (as Gonyaulacysta, now Wrevittia) helicoidea, according to Stover and Helby (1987d, p.287) — however, Jan du Chêne et al. (1986a, p.130) and Lentin and Williams (1989, p.152) retained Gonyaulacysta (now Wrevittia?) diutina.
Holotype: Duxbury, 1977, pl.1, fig.3; text-fig.9; Jan du Chene et al., 1986, pl.41, figs.3-4
Paratype: Duxbury, 1977, pl.1, fig.5
Locus typicus: Speeton Clay, Speeton, England
Stratum typicum: Berriasian-Hauterivian
Original diagnosis: Duxbury 1977, p. 34-35
A small, proximate cyst. Endophragm ellipsoidal, longer than broad, finely granular with a random scatter of small tubercles. Periphragm smooth to finely granular, produced into fairly low sutural crests which are distally denticulate and which outline a tabulation 4", 6"", 6c, ?6""", 1p, 1"""". Apically, the periphragm is produced into a low horn which is bluntly rounded.
Dimensions: Overall 62-68x49-59 µm.
Affinities:
Duxbury 1977, p. 34-35: Gonyaulacysta diutina may be most closely compared with G.helicoidea (Eisenack and Cookson) Sarjeant as illustrated in Sarjeant 1966, but differs in several respects. G.diutina is more elongate and generally larger. The cyst body of G.helicoidea is usually polygonal with a relatively large, flat plate 1"""" whereas that of G.diutina is ellipsoidal with a distinctly convex plate 1"""". The apical horn of G.helicoidea is the most elongate with usually straight to concave sides as opposed to the bluntly rounded horn of G.diutina. Sometimes there is a small pericoel at the base of the horn in G.diutina. Most observed specimens of G.diutina had a lateral orientation suggesting some inherent lateral flattening. All specimens of G.diutina were seen to have a dorso-ventral compression.