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Rhynchodiniopsis whitei
Rhynchodiniopsis whitei (Sarjeant, 1966) Sarjeant, 1982
Now Impagidinium?. Originally Gonyaulacysta, subsequently (and now) Impagidinium?, thirdly Rhynchodiniopsis. Jan du Chêne et al., 1986 questionably retained this species in Impagidinium Stover and Evitt, 1978.
Holotype: Sarjeant, 1966, pl.14, fig.2
Locus typicus: Fetcham Mill, Surrey, England
Stratum typicum: Cenomanian
Original diagnosis: Sarjeant, 1966, p. 127: Gonyaulacysta whitei
A Gonyaulacysta having an ovoidal theca with short, blunt apical horn formed from both shell layers. Tabulation 3", 1a, 6", 6c, 6""", 1p, 1"""": plate boundaries demarcated by moderately high crests, densely and finely perforate, with straight or ragged edges. Cingulum broad, strongly spiral: sulcus sigmoidal, of moderate breadth but widening somewhat posteriorly. (A median dorso-ventral plane would barely intersect the two ends of the sulcus.) Surface of shell smooth or only very minutely granular. Crests bounding antapex supported at the angles by strong, broad spines. Dimensions: holotype: overall length 62 µm, breadth 49 µm: breadth 45.5 µm; length of horn 9 µm.
Original description: Sarjeant, 1966, p. 127-128: Gonyaulacysta whitei
Shell rotund, lemon-shaped, the apical horn joining the shell so smoothly as to have no precise base. Only three apical plates, the crests bounding them forming a pimple on the tip of the apical horn. Plate 1" is elongate and occupies the anterior prolongation of the sulcus: its posterior boundary was not clearly determined. An anterior intercalary plate and six precingular plates are present, plate 6" being reduced and subtriangular. Six postcingular plates are present, plate 1""" being very small and having an ill-defined boundary with the sulcus. The single posterior intercalary plate separates plates 1""" and 2""" from the quadrate antapical plate.
The cingulum forms a laevorotatory spiral such that its two ends differ in antero-posterior position by almost 4 times its breadth. Six cingular plates are present: the ends of plates 1c and 6c extend somewhat into the sulcus. The epitractal portion of the sulcus is of moderate breadth; the hypotractal portion broadens progressively as it approaches the antapex. A precingular archaeopyle is formed by loss of plate 3".
Now Impagidinium?. Originally Gonyaulacysta, subsequently (and now) Impagidinium?, thirdly Rhynchodiniopsis. Jan du Chêne et al., 1986 questionably retained this species in Impagidinium Stover and Evitt, 1978.
Holotype: Sarjeant, 1966, pl.14, fig.2
Locus typicus: Fetcham Mill, Surrey, England
Stratum typicum: Cenomanian
Original diagnosis: Sarjeant, 1966, p. 127: Gonyaulacysta whitei
A Gonyaulacysta having an ovoidal theca with short, blunt apical horn formed from both shell layers. Tabulation 3", 1a, 6", 6c, 6""", 1p, 1"""": plate boundaries demarcated by moderately high crests, densely and finely perforate, with straight or ragged edges. Cingulum broad, strongly spiral: sulcus sigmoidal, of moderate breadth but widening somewhat posteriorly. (A median dorso-ventral plane would barely intersect the two ends of the sulcus.) Surface of shell smooth or only very minutely granular. Crests bounding antapex supported at the angles by strong, broad spines. Dimensions: holotype: overall length 62 µm, breadth 49 µm: breadth 45.5 µm; length of horn 9 µm.
Original description: Sarjeant, 1966, p. 127-128: Gonyaulacysta whitei
Shell rotund, lemon-shaped, the apical horn joining the shell so smoothly as to have no precise base. Only three apical plates, the crests bounding them forming a pimple on the tip of the apical horn. Plate 1" is elongate and occupies the anterior prolongation of the sulcus: its posterior boundary was not clearly determined. An anterior intercalary plate and six precingular plates are present, plate 6" being reduced and subtriangular. Six postcingular plates are present, plate 1""" being very small and having an ill-defined boundary with the sulcus. The single posterior intercalary plate separates plates 1""" and 2""" from the quadrate antapical plate.
The cingulum forms a laevorotatory spiral such that its two ends differ in antero-posterior position by almost 4 times its breadth. Six cingular plates are present: the ends of plates 1c and 6c extend somewhat into the sulcus. The epitractal portion of the sulcus is of moderate breadth; the hypotractal portion broadens progressively as it approaches the antapex. A precingular archaeopyle is formed by loss of plate 3".