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Gonyaulacysta aichmetes
Gonyaulacysta achimetes Sarjeant, 1966
Now Cribroperidinium. Originally Gonyaulacysta, subsequently Millioudodinium, thirdly (and now) Cribroperidinium.
Holotype: Sarjeant, 1966, pl.13, figs.5-6, text-fig.30; Jan du Chene et al., 1986, pl.20, fig.6-7
Locus typicus: Shell West Heslerton Borehole No 1, Yorkshire, England
Stratum typicum: Late Barremian
Original diagnosis: Sarjeant, 1966, p.123-124
A Gonyaulacysta with ovoidal to broadly ellipsoidal theca and strong, tapering apical horn accounting for about one-sixth to one-seventh of overall length. Tabulation 4", 1a, 6"", 6c, 6""", 1p, 1"""". Crests delimiting plates represented by low ridges, minutely serrate; those bordering cingulum higher. Cingulum strongly spiral, of moderate breadth; sulcus sunken, broad, with only short epitractal section. Surface of shell densely granular; granulation less pronounced on sulcus.
Dimensions: Holotype: overall length 101 µm breadth 64 µm (minimum); shell length 84 µm breadth 56 µm (minimum); length of horn 16 µm; width of cingulum c. 4.5 µm. Range of dimensions: overall length c. 95-105 µm, breadth c. 55-65 µm.
Now Cribroperidinium. Originally Gonyaulacysta, subsequently Millioudodinium, thirdly (and now) Cribroperidinium.
Holotype: Sarjeant, 1966, pl.13, figs.5-6, text-fig.30; Jan du Chene et al., 1986, pl.20, fig.6-7
Locus typicus: Shell West Heslerton Borehole No 1, Yorkshire, England
Stratum typicum: Late Barremian
Original diagnosis: Sarjeant, 1966, p.123-124
A Gonyaulacysta with ovoidal to broadly ellipsoidal theca and strong, tapering apical horn accounting for about one-sixth to one-seventh of overall length. Tabulation 4", 1a, 6"", 6c, 6""", 1p, 1"""". Crests delimiting plates represented by low ridges, minutely serrate; those bordering cingulum higher. Cingulum strongly spiral, of moderate breadth; sulcus sunken, broad, with only short epitractal section. Surface of shell densely granular; granulation less pronounced on sulcus.
Dimensions: Holotype: overall length 101 µm breadth 64 µm (minimum); shell length 84 µm breadth 56 µm (minimum); length of horn 16 µm; width of cingulum c. 4.5 µm. Range of dimensions: overall length c. 95-105 µm, breadth c. 55-65 µm.