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Acanthaulax compta
Acanthaulax compta, (Duxbury, 1980, p. 122-123, pl. 2, figs. 1-2,4), Sarjeant, 1982b, p. 47.
Originally Gonyaulacysta, subsequently Cribroperidinium, thirdly Acanthaulax, fourthly Apteodinium.
Taxonomic senior synonym: Millioudodinium (now Cribroperidinium) spinoreticulatum, according to Lucas-Clark (1987, p.178).
Holotype: Duxbury, 1980, pl.2, figs.1-2,4; Jan du Chêne et al., 1986a, pl.10, figs.9-10.
Age: Mid-Late Barremian.
Locus typicus: Speeton Clay, Speeton, England
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Original description as Gonyaulacysta compta: [Duxbury, 1980, p. 122]:
Diagnosis:
A fairly thick-walled dinoflagellate cyst with a spheroidal to ellipsoidal body surmounted by a distinct apical horn.
Paratabulation typical for the genus is outlined by generally low, distally entire parasutural crests which are sometimes perforate. The paraplates are completely covered by short, conical spines, each of which have ridges radiating from their bases onto the body surface. The paraplate areas are, therefore, covered by a complex system of fine ridges.
The archeopyle is precingular, formed by displacement of paraplate 3".
Dimensions: Holotype 80x64 µm. Overall 97(83)76x76(65)54 µm.
Affinities:
In its overall morphology, G. compta resembles Trichodinium castaneum (Deflandre, 1935) Clarke & Verdier, 1967, especially in the ornament of conical spines and surface ridges. G. compta differs, however, in having a distinct apical horn (T. castaneum displays only an apical "tuft") and in displaying a complete paratabulation pattern (the genus Trichodinium lacks paratabulation except that the paracingulum and parasulcus may often be seen).
Originally Gonyaulacysta, subsequently Cribroperidinium, thirdly Acanthaulax, fourthly Apteodinium.
Taxonomic senior synonym: Millioudodinium (now Cribroperidinium) spinoreticulatum, according to Lucas-Clark (1987, p.178).
Holotype: Duxbury, 1980, pl.2, figs.1-2,4; Jan du Chêne et al., 1986a, pl.10, figs.9-10.
Age: Mid-Late Barremian.
Locus typicus: Speeton Clay, Speeton, England
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Original description as Gonyaulacysta compta: [Duxbury, 1980, p. 122]:
Diagnosis:
A fairly thick-walled dinoflagellate cyst with a spheroidal to ellipsoidal body surmounted by a distinct apical horn.
Paratabulation typical for the genus is outlined by generally low, distally entire parasutural crests which are sometimes perforate. The paraplates are completely covered by short, conical spines, each of which have ridges radiating from their bases onto the body surface. The paraplate areas are, therefore, covered by a complex system of fine ridges.
The archeopyle is precingular, formed by displacement of paraplate 3".
Dimensions: Holotype 80x64 µm. Overall 97(83)76x76(65)54 µm.
Affinities:
In its overall morphology, G. compta resembles Trichodinium castaneum (Deflandre, 1935) Clarke & Verdier, 1967, especially in the ornament of conical spines and surface ridges. G. compta differs, however, in having a distinct apical horn (T. castaneum displays only an apical "tuft") and in displaying a complete paratabulation pattern (the genus Trichodinium lacks paratabulation except that the paracingulum and parasulcus may often be seen).