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Cribroperidinium orthoceras
Gonyaulacysta orthoceras (Eisenack, 1958) Davey, 1969; emend. Sarjeant, 1985
Originally Gonyaulax, subsequently Gonyaulacysta, thirdly (and now) Cribroperidinium.
Tax. jr. synonym of Cribroperidinium edwardsii (Cookson and Eisenack, 1958) Davey, 1969, according to Davey and Verdier, 1971, Stover and Evitt, 1978, and Lentin and Williams, 1981. Below, 1981, Helenes, 1984, and Lentin and Williams, 1985, retained Cribroperidinium orthoceras as a separate species.
Helenes, 1984, and Jan du Chêne et al., 1986, considered this to be a problematic species of Cribroperidinium.
Lentin and Williams, 1973, retained this species in Cribroperidinium.
Singh, 1971, and Dodekova, 1971, included the species in Gonyaulacysta.
Lentin and Williams, 1973, did not accept the above transfers.
Holotype: Eisenack, 1958, pl.21, fig.5; Sarjeant, 1985, pl.1, figs.1-4, text-fig.1; Jan du Chêne et al., 1986, pl.24, figs.7-8
Locus typicus: Northern Germany
Stratum typicum: Aptian
Translation Eisenack, 1958: Sarjeant, 1985
Original diagnosis: Eisenack, 1958, p. 388-389: Gonyaulax orthoceras
Shell apparently thick-walled, oval, with roughly hemispherical hypotheca, with strong, thornlike apical horn of about 1/4 the overall length. Transverse furrow spiral, enclosed by low but strong crests. Tabulation largely clear; plate boundaries marked by narrow, very low crests which, like the plates themselves, bear short spinelets or tubercles. Pylome trapezoidal, usually higher than broad, common.
Emended diagnosis: Sarjeant, 1985, p.121
A Gonyaulacysta having an ovoidal theca of moderate wall thickness, with strong, tapering apical horn accounting for about one-fifth to onequarter of overall length. Tabulation 4", 1a, 6", ?6c, 7""", 1p, 1""""; plate boundaries outlined by low crests bearing very abbreviate spinelets. Cingulum strongly spiral, of moderate breadth: sulcus broad and extending to antapex. Surface of shell granular to tuberculate.
Range of German specimens: overall length 70-105 Ám. Range of English specimens; overall length 80-115 Ám.
Emended description: Sarjeant, 1966, p. 122
Shell broadly ovoidal, with the hypotract rounded. The crests separating the four apical plates converge at the apex. Plate 1" occupies the anterior prolongation of the sulcus and is markedly elongate. Six precingular plates are present, with plate 6" very reduced to accommodate an anterior intercalary plate. Seven postcingular plates are present, plates 1""" and 2""" being reduced to accommodate a rather indistinctly demarcated posterior intercalary plate. A single polygonal plate occupies the antapex.
The cingulum forms a laevorotatory spiral such that its two ends differ in anteroposterior position by over three times its width. The number of cingular plates appears to be six, but the crests separating them are poorly marked. The sulcus is of moderate breadth and extends from mid-point on the epitract to the antapex.
The shell wall is of moderate thickness and consists of two distinct layers. The apical horn is formed by the periphragm, the endophragm showing no outbulge; the horn is thus hollow and contains what is effectively an apical pericoel. The English specimens have a densely granular surface, but lack tubercles such as are present on the German specimens.
A precingular archaeopyle, formed by loss of plate 3", is generally present.
Originally Gonyaulax, subsequently Gonyaulacysta, thirdly (and now) Cribroperidinium.
Tax. jr. synonym of Cribroperidinium edwardsii (Cookson and Eisenack, 1958) Davey, 1969, according to Davey and Verdier, 1971, Stover and Evitt, 1978, and Lentin and Williams, 1981. Below, 1981, Helenes, 1984, and Lentin and Williams, 1985, retained Cribroperidinium orthoceras as a separate species.
Helenes, 1984, and Jan du Chêne et al., 1986, considered this to be a problematic species of Cribroperidinium.
Lentin and Williams, 1973, retained this species in Cribroperidinium.
Singh, 1971, and Dodekova, 1971, included the species in Gonyaulacysta.
Lentin and Williams, 1973, did not accept the above transfers.
Holotype: Eisenack, 1958, pl.21, fig.5; Sarjeant, 1985, pl.1, figs.1-4, text-fig.1; Jan du Chêne et al., 1986, pl.24, figs.7-8
Locus typicus: Northern Germany
Stratum typicum: Aptian
Translation Eisenack, 1958: Sarjeant, 1985
Original diagnosis: Eisenack, 1958, p. 388-389: Gonyaulax orthoceras
Shell apparently thick-walled, oval, with roughly hemispherical hypotheca, with strong, thornlike apical horn of about 1/4 the overall length. Transverse furrow spiral, enclosed by low but strong crests. Tabulation largely clear; plate boundaries marked by narrow, very low crests which, like the plates themselves, bear short spinelets or tubercles. Pylome trapezoidal, usually higher than broad, common.
Emended diagnosis: Sarjeant, 1985, p.121
A Gonyaulacysta having an ovoidal theca of moderate wall thickness, with strong, tapering apical horn accounting for about one-fifth to onequarter of overall length. Tabulation 4", 1a, 6", ?6c, 7""", 1p, 1""""; plate boundaries outlined by low crests bearing very abbreviate spinelets. Cingulum strongly spiral, of moderate breadth: sulcus broad and extending to antapex. Surface of shell granular to tuberculate.
Range of German specimens: overall length 70-105 Ám. Range of English specimens; overall length 80-115 Ám.
Emended description: Sarjeant, 1966, p. 122
Shell broadly ovoidal, with the hypotract rounded. The crests separating the four apical plates converge at the apex. Plate 1" occupies the anterior prolongation of the sulcus and is markedly elongate. Six precingular plates are present, with plate 6" very reduced to accommodate an anterior intercalary plate. Seven postcingular plates are present, plates 1""" and 2""" being reduced to accommodate a rather indistinctly demarcated posterior intercalary plate. A single polygonal plate occupies the antapex.
The cingulum forms a laevorotatory spiral such that its two ends differ in anteroposterior position by over three times its width. The number of cingular plates appears to be six, but the crests separating them are poorly marked. The sulcus is of moderate breadth and extends from mid-point on the epitract to the antapex.
The shell wall is of moderate thickness and consists of two distinct layers. The apical horn is formed by the periphragm, the endophragm showing no outbulge; the horn is thus hollow and contains what is effectively an apical pericoel. The English specimens have a densely granular surface, but lack tubercles such as are present on the German specimens.
A precingular archaeopyle, formed by loss of plate 3", is generally present.