From Fensome et al., 2019:
Abratopdinium cardioforme, Mao Shaozhi and Mohr, 1992, p.318, pl.1, figs.3-4
Holotype: Mao Shaozhi and Mohr, 1992, pl.1, fig.4
Age: Late Campanian-Early Maastrichtian

Locus typicus: ODP Hole 748c, Banzare Bank, S Indian Ocean
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Original description: [Mao Shaozhi and Mohr, 1992]:

Description:
Cyst circumcavate, ambital outline heartlike, rounded rhombic to rounded pentagonal. Epicyst is rounded triangular; hypocyst is rounded or slightly concave at antapex, but without any indications of horns or projections.
Wall two layered; both periphragm and endophragm are thin. The periphragm is smooth or with scattered apiculae of about 1x1 µm; the endophragm is smooth and hyaline, as a result, the endocyst is faintly visible.
Paracingulum usually present, slightly levorotatory, 4-7 µm wide, indicated by low ridges, clearly seen along the cyst margin. Parasulcus, where present, is limited to the hypocyst.
Archeopyle intercalary [2a], standard hexastyle, iso-thetaform; operculum usually free.

Dimensions/Size:
Length of cysts, 34.5-49 (holotype 45.8) µm; width of cysts, 33-53.2 (holotype 53.1) µm; 20 specimens measured.

Affinities:
Abratopdinium cardioforme differs from A. kerguelense in its heartlike shape and delicately apiculate periphragm.