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Rhombodinium elegans
Rhombodinium elegans He Chengquan, 1991
Holotype: He Chengquan, 1991, pl.39, fig.8
Age: Middle Eocene
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: The cyst is dorsal-ventral flattened, contour is like a kite or elongated pentagon. The lateral sides are nearly straight and each corner develops a horn, divided into nearly equal parts by the cingulum. Upper cyst triangular , with a apical horn, conical or triangular, length 16-24μm, its base contracts obviously or inconspicuously, the top is often decorated with a small ring or ball. Hypocyst is inverted trapezoid, the bottom side is wide flat or curved, with two antapical horns, conical, 14-26μm long, nearly equal or the left horn is slightly larger, tip blunt or pointed, (40-50μm, generally 50μm). 2 lateral horns are strong, trapezoid, becoming slightly thinner slightly, the end is concave, length 14 - 18μm, the base width 25-32μm, the end width 5 -10μm. Cingulum goes through the lateral horns, ring, obvious or relatively obscure. The surface of the outer wall is finely grained → nearly smooth, and the outline is smooth. The inner body contour is a regular oval, slightly extending into the lateral horn or not, the wall is thin, the surface is smooth or fine- rough granular; Except at the horns, it is separated from the outer wall with a narrow external cavity (0.5- 4μm). Archeopyle is very clear, intercalary, the outline is round trapezoid, length larger than width or nearly equal, it is obviously not connected with the top of the external cavity. The operculum is completely separated and stored in place.
Cyst length 127-155μm, width 102-127μm, inner body length 95-103μm, width 80-97 .5μm (measured 9); Holotype length 155μm, width 122.5μm, inner body length 100μm, width 87 .5μm, apical horn length 22.5μm, lateral horn length 18μm, antapical horn length 18-2 8μm.
Comparison: This species if different from Rhombodinium wuqiaense, in elongated cyst, regular oval inner body, no obvious ornamentation on the outer wall surface, near smooth contour and disconnection between the archeopyle and top external cavity; It differs from R. sinense. In length larger than width, lateral horn trapezoidal and non-elongation, lack of bar thorns at the end and two nearly equal antapical horn.
Location and stratigraphy: Wucha County Basebulak and Shache County Quruimu; Wulagen fm.
Holotype: He Chengquan, 1991, pl.39, fig.8
Age: Middle Eocene
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: The cyst is dorsal-ventral flattened, contour is like a kite or elongated pentagon. The lateral sides are nearly straight and each corner develops a horn, divided into nearly equal parts by the cingulum. Upper cyst triangular , with a apical horn, conical or triangular, length 16-24μm, its base contracts obviously or inconspicuously, the top is often decorated with a small ring or ball. Hypocyst is inverted trapezoid, the bottom side is wide flat or curved, with two antapical horns, conical, 14-26μm long, nearly equal or the left horn is slightly larger, tip blunt or pointed, (40-50μm, generally 50μm). 2 lateral horns are strong, trapezoid, becoming slightly thinner slightly, the end is concave, length 14 - 18μm, the base width 25-32μm, the end width 5 -10μm. Cingulum goes through the lateral horns, ring, obvious or relatively obscure. The surface of the outer wall is finely grained → nearly smooth, and the outline is smooth. The inner body contour is a regular oval, slightly extending into the lateral horn or not, the wall is thin, the surface is smooth or fine- rough granular; Except at the horns, it is separated from the outer wall with a narrow external cavity (0.5- 4μm). Archeopyle is very clear, intercalary, the outline is round trapezoid, length larger than width or nearly equal, it is obviously not connected with the top of the external cavity. The operculum is completely separated and stored in place.
Cyst length 127-155μm, width 102-127μm, inner body length 95-103μm, width 80-97 .5μm (measured 9); Holotype length 155μm, width 122.5μm, inner body length 100μm, width 87 .5μm, apical horn length 22.5μm, lateral horn length 18μm, antapical horn length 18-2 8μm.
Comparison: This species if different from Rhombodinium wuqiaense, in elongated cyst, regular oval inner body, no obvious ornamentation on the outer wall surface, near smooth contour and disconnection between the archeopyle and top external cavity; It differs from R. sinense. In length larger than width, lateral horn trapezoidal and non-elongation, lack of bar thorns at the end and two nearly equal antapical horn.
Location and stratigraphy: Wucha County Basebulak and Shache County Quruimu; Wulagen fm.