Chatangiella magna, (Davey, 1970), Lentin and Williams, 1976

Now Isabelidinium. Originally Deflandrea, subsequently Chatangiella, thirdly (and now) Isabelidinium.

Holotype: Davey, 1970, pl.2, figs.6-8
Locus typicus: Saskatchewan, Canada
Stratum typicum: Cenomanian

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Original description as Deflandrea magna: [Davey, 1970, p. 342-343]:

Diagnosis:
Shell elongate-ovoidal, truncated posteriorly with single, pointed antapical horn. Epitract subconical, apical horn not differentiated.
Outer membrane smooth or slightly granular, enclosing subspherical inner body. Inner body and outer membrane sometimes in contact laterally but more often separated by narrow space.
Cingulum, on outer membrane, well defined, weakly spiral, marked by low ledges having knobbly margin. Sulcus broad.
Archaeopyle subpolygonal, operculum typically in place

Description:
Due to the fineness of the outer membrane, it is always folded to some extent.
The cingulum (7 to 10 µm in width) is slightly concave and is sometimes crossed by low ridges marking the cingular plate boundaries. The lower boundary of the cingulum is occasionally interrupted.
The archaeopyle is elongate-ovoidal anteriorly and polygonal posteriorly; the operculum typically remains in position.
The inner body possesses a slightly thicker wall, is subspherical rarely with a posterior concavity, and usually has an apical region composed of disarranged plates. Sometimes the three anterior intercalary plates arc obvious. Rarely the latter plates, together with the apical plates, are absent.

Dimensions:
Range: overall length 69 (95.9) 118 µm, overall width 49 (64.7) 85 µm, length of inner body 36 (51.0) 61 µm width of inner body 43 (51.6) 57 µm.