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Gonyaulacysta fimbriata
Gonyaulacysta fimbriata Duxbury, 1980
Now Rhynchodiniopsis. Originally Gonyaulacysta, subsequently (and now) Rhynchodiniopsis.
Taxonomic senior synonym: Rhynchodiniopsis aptiana, according to Below (1981a, p.118) — however, Sarjeant (1982b, p.36) and Jan du Chêne et al. (1986a, p.287) retained Gonyaulacysta (as Rhynchodiniopsis) fimbriata.
Holotype: Duxbury, 1980, pl.1, figs.1,2; Jan du Chene et al., 1986, pl.98, figs.1-2
Locus typicus: Speeton Clay, Speeton, England
Stratum typicum: Barremian
Original diagnosis: Duxbury, 1980, p.123
A large dinoflagellate cyst with both epi- and hypocyst triangular in dorso-ventral view. A pronounced apical horn is always present and the body surface is finely reticulate. Paratabulation of the formula 4", 2a, 6", ?c, 6""", 1p, 1p.v., 1"""", is outlined by generally low parasutural crests. In the epi- and hypocystal regions, these crests are low, distally entire or sparsely denticulate and proximally perforate. The epicystal crests are lower than those of the hypocyst except for those on the apical horn which impart a feathered effect to this structure and which coalesce and extend for some distance beyond the horn tip, terminating in a coronate structure. The paracingular crests are most distinctive in so far as they differ from each other and from all the other crests. The posterior paracingular crest is fairly low and bears a closely-spaced, regular row of flat-ended denticles. The anterior paracingular crest, on the other hand, is high, distally entire and highly fenestrate. The antapical paraplate is typically formed into a distinct, broadly-rounded protuberance. The archeopyle is single-paraplate precingular (3").
Observed dimensions: Holotype 151x136 Ám. Overall 151(123)111x136(114)95 Ám.
Affinities:
Duxbury, 1980, p. 123: This is a most distinctive species, remarkable mainly in the structure of the paracingular crests. The fenestrate, anterior paracingular crest is very high and is commonly so high as to make the overall width of the cyst greater than the overall length. Consequently, G.fimbriata is often observed in polar orientation and in this orientation the anterior paracingular crest is reminiscent of the paracingular crest of Wanea fimbriata (Sarjeant, 1961).
Now Rhynchodiniopsis. Originally Gonyaulacysta, subsequently (and now) Rhynchodiniopsis.
Taxonomic senior synonym: Rhynchodiniopsis aptiana, according to Below (1981a, p.118) — however, Sarjeant (1982b, p.36) and Jan du Chêne et al. (1986a, p.287) retained Gonyaulacysta (as Rhynchodiniopsis) fimbriata.
Holotype: Duxbury, 1980, pl.1, figs.1,2; Jan du Chene et al., 1986, pl.98, figs.1-2
Locus typicus: Speeton Clay, Speeton, England
Stratum typicum: Barremian
Original diagnosis: Duxbury, 1980, p.123
A large dinoflagellate cyst with both epi- and hypocyst triangular in dorso-ventral view. A pronounced apical horn is always present and the body surface is finely reticulate. Paratabulation of the formula 4", 2a, 6", ?c, 6""", 1p, 1p.v., 1"""", is outlined by generally low parasutural crests. In the epi- and hypocystal regions, these crests are low, distally entire or sparsely denticulate and proximally perforate. The epicystal crests are lower than those of the hypocyst except for those on the apical horn which impart a feathered effect to this structure and which coalesce and extend for some distance beyond the horn tip, terminating in a coronate structure. The paracingular crests are most distinctive in so far as they differ from each other and from all the other crests. The posterior paracingular crest is fairly low and bears a closely-spaced, regular row of flat-ended denticles. The anterior paracingular crest, on the other hand, is high, distally entire and highly fenestrate. The antapical paraplate is typically formed into a distinct, broadly-rounded protuberance. The archeopyle is single-paraplate precingular (3").
Observed dimensions: Holotype 151x136 Ám. Overall 151(123)111x136(114)95 Ám.
Affinities:
Duxbury, 1980, p. 123: This is a most distinctive species, remarkable mainly in the structure of the paracingular crests. The fenestrate, anterior paracingular crest is very high and is commonly so high as to make the overall width of the cyst greater than the overall length. Consequently, G.fimbriata is often observed in polar orientation and in this orientation the anterior paracingular crest is reminiscent of the paracingular crest of Wanea fimbriata (Sarjeant, 1961).