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Lacunodinium foveolatum
Lacunodinium foveolatum He Chengquan, 1984
Holotype: He Chengquan, 1984, pl.1, figs.2a-b
Age: Middle Eocene
Description: Tests have some dorso-ventral flattening; contour subcircular or elliptical; length slightly greater than width. No apical or antapical horns.Wall fairly thick (3 to 4 µm), composed of closely appressed endophragm and periphragm. Periphragm much thicker than endophragm and displaying a fibrous structure. Surface conspicuously foveolate. Foveae circular (about 1 Ám in diameter) or subcircular to elliptical, passing through only a part of the periphragm. Contour line of test has small convexes and concaves. Endophragm 0.8 to 1 µm in thickness; compact and structureless. Archaeopyle present, but no cingulum, sulcus or tabulation. Archaeopyle conspicuous, with a horse-shoe contour, precingular, and formed by the migration or falling away of third precingular plate. operculum completely separated but maintaining original position or lying within test cavity or adhering to side of archaeopyle.
Size: Tests 67.5 µm long and 57.5 to 62.5 µm wide (two specimens measured). Holotype 67.5 µm long and 57.5 µm wide.
Note: This species is characterized by a thick test wall and a foveolate surface.
Locality and Horizon: Bashibulake, in Wuqia County: Wulagen Formation.
Holotype: He Chengquan, 1984, pl.1, figs.2a-b
Age: Middle Eocene
Description: Tests have some dorso-ventral flattening; contour subcircular or elliptical; length slightly greater than width. No apical or antapical horns.Wall fairly thick (3 to 4 µm), composed of closely appressed endophragm and periphragm. Periphragm much thicker than endophragm and displaying a fibrous structure. Surface conspicuously foveolate. Foveae circular (about 1 Ám in diameter) or subcircular to elliptical, passing through only a part of the periphragm. Contour line of test has small convexes and concaves. Endophragm 0.8 to 1 µm in thickness; compact and structureless. Archaeopyle present, but no cingulum, sulcus or tabulation. Archaeopyle conspicuous, with a horse-shoe contour, precingular, and formed by the migration or falling away of third precingular plate. operculum completely separated but maintaining original position or lying within test cavity or adhering to side of archaeopyle.
Size: Tests 67.5 µm long and 57.5 to 62.5 µm wide (two specimens measured). Holotype 67.5 µm long and 57.5 µm wide.
Note: This species is characterized by a thick test wall and a foveolate surface.
Locality and Horizon: Bashibulake, in Wuqia County: Wulagen Formation.