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Leptodinium impenseum
Leptodinium impenseum Yu Jingxian, 1982
Taxonomic junior synonym: Leptodinium quadrangulum, according to He Chengquan et al. (2009, p.107).
Holotype: Yu Jingxian, 1982, pl.2, fig.10
Age: Late Jurassic-Early Cretaceous
Description: Proximate cysts, trapezoidal in dorsoventral view. Length and width almost equivalent. Apical end truncated . No apical horn . Periphragm and endophragm. [Periphragm has] granulate ornamentation. Parasutures low and flat. Very slight showing at distal end of sparsely scattered blunt teeth. Paratabulation shows as in genus. Precingular archeopyle, formed by loss of paraplate 3"". Archeopyle trapezoidal in outline. Paracingulum somewhat helical, 13.8 Ám wide, decorated on edges with ribs of stout ridges, conspicuously projecting beyond the cyst. Paracingulum divides the cyst into roughly equal upper and lower parts. Epicyst trapezoidal. Hypocyst basin-shaped. Parasulcus extends to lower part of epicyst.
Size: Cysts 72 - 74.6 µm long and 80 - 87 µm wide.
Comparison: The new species resembles L. quadrangulum (sp. nov.) in the projection of its paracingulum beyond the cyst and in its trapezoidal contour but is distinguished from the latter by its broad paracingulum, with an ornamentation of stout ridges on its edges, and its trapezoidal precingular archeopyle.
Taxonomic junior synonym: Leptodinium quadrangulum, according to He Chengquan et al. (2009, p.107).
Holotype: Yu Jingxian, 1982, pl.2, fig.10
Age: Late Jurassic-Early Cretaceous
Description: Proximate cysts, trapezoidal in dorsoventral view. Length and width almost equivalent. Apical end truncated . No apical horn . Periphragm and endophragm. [Periphragm has] granulate ornamentation. Parasutures low and flat. Very slight showing at distal end of sparsely scattered blunt teeth. Paratabulation shows as in genus. Precingular archeopyle, formed by loss of paraplate 3"". Archeopyle trapezoidal in outline. Paracingulum somewhat helical, 13.8 Ám wide, decorated on edges with ribs of stout ridges, conspicuously projecting beyond the cyst. Paracingulum divides the cyst into roughly equal upper and lower parts. Epicyst trapezoidal. Hypocyst basin-shaped. Parasulcus extends to lower part of epicyst.
Size: Cysts 72 - 74.6 µm long and 80 - 87 µm wide.
Comparison: The new species resembles L. quadrangulum (sp. nov.) in the projection of its paracingulum beyond the cyst and in its trapezoidal contour but is distinguished from the latter by its broad paracingulum, with an ornamentation of stout ridges on its edges, and its trapezoidal precingular archeopyle.