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Cribroperidinium spinoreticulatum
From Fensome et al., 2019:
Cribroperidinium spinoreticulatum (McIntyre and Brideaux, 1980, p.15–16, pl.3, figs.4,8–12) Århus, 1992, p.310. Holotype:
McIntyre and Brideaux, 1980, pl.3, figs.4,9,12; Jan du Chêne et al., 1986a, pl.13, figs.9–11. Originally
Millioudodinium, subsequently Apteodinium, thirdly (and now) Cribroperidinium. Taxonomic junior synonym:
Gonyaulacysta (as Apteodinium) compta, according to Lucas-Clark (1987, p.178). Age: Valanginian.
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Original diagnosis: McIntyre and Brideaux, 1980, p.15-16: Millioudodinium spinoreticulatum
Shape: Pericyst - Ambitus ovoid to rounded-pentagonal, longer than broad; apical horn, 7-16 µm in length, with a distal notched cap. Dorsoventral compression.
Endocyst - Commonly present, but difficult to delineate; everywhere closely appressed to the pericyst; apical horn as for pericyst; dorsoventral compression.
Pericoels - absent.
Phragma: Periphragm - 0.5-1.0 µm thick; surface sculpture consists of parasutural ridges together with an irregularly anastomosing or more regular system of low
ridges which may form an imperfect to perfect reticulum; ridges less than 0.5 µm high and less than 0.25 µm wide; bearing spines, from 1.0-2.0 µm high (typically about 1.0 µm) distributed randomly on the ridges and on more prominent parasutural ridges. Endophragm - Less than 0.5 µm thick, commonly obscure; presumably smooth.
Paratabulation: Pericyst - Parasutural ridges denote a paratabulation determined approximately as 4', ?6'', ?6c, ?6''', ?1p, 1''''. Parasutural ridges are obscured in places by the intratabular reticulum. Endocyst - Paratabulation not observed.
Pericingulum - Present, distinct, slightly indented, helicoid; with ?six cingular paraplates. Perisulcus - Present as a shallow depression, the details difficult to delineate; narrow anteriorly, widest posteriorly; extending about one-third of the way up the epipericyst. Archeopyle. Precingular, Type P(3"). Operculum free, simple, longer than broad, strongly rounded, gibbous-shaped.
Variation: The degree of reticulation is more or less constant for a given specimen, but varies widely between specimens; in places on a given specimen, the spines may be discrete.
Dimensions: Pericyst length 70-87 µm, width 55-70 µm.
Affinites:
McIntyre and Brideaux, 1980, p. 16: Millioudodinium spinoreticulatum
The intratabular spine-bearing network of low ridges distinguishes this species from other similar species of Millloudodinium.
Cribroperidinium spinoreticulatum (McIntyre and Brideaux, 1980, p.15–16, pl.3, figs.4,8–12) Århus, 1992, p.310. Holotype:
McIntyre and Brideaux, 1980, pl.3, figs.4,9,12; Jan du Chêne et al., 1986a, pl.13, figs.9–11. Originally
Millioudodinium, subsequently Apteodinium, thirdly (and now) Cribroperidinium. Taxonomic junior synonym:
Gonyaulacysta (as Apteodinium) compta, according to Lucas-Clark (1987, p.178). Age: Valanginian.
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Original diagnosis: McIntyre and Brideaux, 1980, p.15-16: Millioudodinium spinoreticulatum
Shape: Pericyst - Ambitus ovoid to rounded-pentagonal, longer than broad; apical horn, 7-16 µm in length, with a distal notched cap. Dorsoventral compression.
Endocyst - Commonly present, but difficult to delineate; everywhere closely appressed to the pericyst; apical horn as for pericyst; dorsoventral compression.
Pericoels - absent.
Phragma: Periphragm - 0.5-1.0 µm thick; surface sculpture consists of parasutural ridges together with an irregularly anastomosing or more regular system of low
ridges which may form an imperfect to perfect reticulum; ridges less than 0.5 µm high and less than 0.25 µm wide; bearing spines, from 1.0-2.0 µm high (typically about 1.0 µm) distributed randomly on the ridges and on more prominent parasutural ridges. Endophragm - Less than 0.5 µm thick, commonly obscure; presumably smooth.
Paratabulation: Pericyst - Parasutural ridges denote a paratabulation determined approximately as 4', ?6'', ?6c, ?6''', ?1p, 1''''. Parasutural ridges are obscured in places by the intratabular reticulum. Endocyst - Paratabulation not observed.
Pericingulum - Present, distinct, slightly indented, helicoid; with ?six cingular paraplates. Perisulcus - Present as a shallow depression, the details difficult to delineate; narrow anteriorly, widest posteriorly; extending about one-third of the way up the epipericyst. Archeopyle. Precingular, Type P(3"). Operculum free, simple, longer than broad, strongly rounded, gibbous-shaped.
Variation: The degree of reticulation is more or less constant for a given specimen, but varies widely between specimens; in places on a given specimen, the spines may be discrete.
Dimensions: Pericyst length 70-87 µm, width 55-70 µm.
Affinites:
McIntyre and Brideaux, 1980, p. 16: Millioudodinium spinoreticulatum
The intratabular spine-bearing network of low ridges distinguishes this species from other similar species of Millloudodinium.