Apteodinium spinoreticulatum, (McIntyre and Brideaux, 1980), Helenes, 1984

NOW Cribroperidinium. Originally Millioudodinium, subsequently Apteodinium, thirdly (and now) Cribroperidinium.
Tax. sr synonym of Apteodinium comptum (Duxbury, 1980) Helenes, 1984, according to Lucas-Clark, 1987.

Holotype: McIntyre and Brideaux, 1980, pl.3, figs.4,9,12; Jan du Chêne et al., 1986, pl.13, figs.9-11
Locus typicus: "Grizzly Gorge", District of Mackenzie, Canada
Stratum typicum: Valanginian

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Original description as Millioudodinium spinoreticulatum: [McIntyre and Brideaux, 1980, p. 15-16]:

Diagnosis:
Shape: Pericyst - Ambitus ovoid to rounded-pentagonal, longer than broad; apical horn, 7-16 um 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:
The intratabular spine-bearing network of low ridges distinguishes this species from other similar species of Millloudodinium.