From Fensome et al., 2019:
Xuidinium laevigatum Mao Shaozhi and Norris, 1988, p.54, pl.16, figs.7–11.
Holotype: Mao Shaozhi and Norris, 1988, pl.16, fig.10; Fensome et al., 1995, fig.3 — p.1593.
Paratype: Mao Shaozhi and Norris, 1988
Locus typicus: Tarim Basin, Xinjiang Province, China
Stratum typicum: Qimugen Formation, Simuhana section, upper Paleocene

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Original description: Mao Shaozhi and Norris, 1988:

Diagnosis:
Cyst proximate, ambitus rounded-biconical to ovoidal with an apical prominence and a small left antapical prominence. Autophragm smooth and thin. Archeopyle intercalary, type I, standard hexa-2a style.

Description:
Epitract triangular with two sides convex, into which the apical prominence merges imperceptibly. Hypotract equal in size to epitract, semieliptical to rounded-triangular with a small left antapical prominence near the longitudinal axis. Autophragm slightly bulging at the presumed position of the right antapical horn. Autophragm thin and smooth, readily folded, slightly distorting the ambitus.
Tabulation indicated by archeopyle only or by both archeopyle and cingulum. The latter, when discernible, defined by folds.
Archeopyle standard hexa style; transverse Al 0.4 to 0.6. In one specimen the open sutures indicate a 3I archeopyle, which may be an archeopyle variation of this species.

Dimensions:
Length 51 to 64 µm (holotype 56 µm), width 37 to 52 µm (holotype 43 µm); 15 specimens measured.