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Rhombodinium cerciatum
Rhombodinium cerciatum He Chengquan, 1991
Holotype: He Chengquan, 1991, pl.36, fig.8
Age: Late Eocene
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: The cyst is dorsal-ventral flattened, contour nearly square, length is slightly smaller than the width, side straight or slightly concave. a cone-shaped apical horn extends at the top, about 20μm long 1). Lateral horns are developed, 20-22μm long, slightly thin towards the distal pole , the end is concave, spiny or dentate. The two antapical horns are located on either side of the body, small, equal size, conical, 5-7.5μm long (measured from the base of the antapical horn). The cingulum is obvious on both lateral horns, but forming two transversal wrinkles on the ventral dorsal sides as a symbol. The outer wall surface has small dentate processes, which can be distributed linearly locally, but not yet formed a reliable polygonal member. The outline of the inner body is rhombus-round square
1) In the species of the genus, the apical, antapical and lateral horns are measured from the side of the inner body, except if indicated. Shape, obviously convex at the lateral horns, the surface is finely granular- nearly smooth. The archeopyle is intercalary style, outline round trapezoid. The operculum is completely separated and stored in situ. Cyst length 138μm, width 145μm, inner body length 90μm, width 105μm.
Comparison: This new species is different from Rhombodinium denticulatum with two small antapical horns which are nearly equal and connected at base; It differs from R. intermedium in two developed lateral horns; It differs from R. ornatum (Wilson) in small equal antapical horns, round square inner body and the outer wall surface without perforation.
Location and stratigraphy: Wuqia County Basebulak; Basebulak fm member two and three.
Holotype: He Chengquan, 1991, pl.36, fig.8
Age: Late Eocene
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: The cyst is dorsal-ventral flattened, contour nearly square, length is slightly smaller than the width, side straight or slightly concave. a cone-shaped apical horn extends at the top, about 20μm long 1). Lateral horns are developed, 20-22μm long, slightly thin towards the distal pole , the end is concave, spiny or dentate. The two antapical horns are located on either side of the body, small, equal size, conical, 5-7.5μm long (measured from the base of the antapical horn). The cingulum is obvious on both lateral horns, but forming two transversal wrinkles on the ventral dorsal sides as a symbol. The outer wall surface has small dentate processes, which can be distributed linearly locally, but not yet formed a reliable polygonal member. The outline of the inner body is rhombus-round square
1) In the species of the genus, the apical, antapical and lateral horns are measured from the side of the inner body, except if indicated. Shape, obviously convex at the lateral horns, the surface is finely granular- nearly smooth. The archeopyle is intercalary style, outline round trapezoid. The operculum is completely separated and stored in situ. Cyst length 138μm, width 145μm, inner body length 90μm, width 105μm.
Comparison: This new species is different from Rhombodinium denticulatum with two small antapical horns which are nearly equal and connected at base; It differs from R. intermedium in two developed lateral horns; It differs from R. ornatum (Wilson) in small equal antapical horns, round square inner body and the outer wall surface without perforation.
Location and stratigraphy: Wuqia County Basebulak; Basebulak fm member two and three.