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Rhombodinium sinense
Rhombodinium sinense He Chengquan, 1991, p.99–100, pl.42, figs.1–6.
Holotype: He Chengquan, 1991, pl.42, fig.3.
Age: middle Eocene.
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: The cyst is dorsal-ventral flattened, outline transversely elongated pentagonal, width larger than length or roughly equal to each other, sides concave. A conical apical horn is strong, 25-32μm long, the top circlar, with sparse particles or short spines; Both lateral horns are very developed, more or less cylindrical, 20-45μm long, tapering distally, end open or concave, often with simple decorations, such as short rod-thorns, coarse particles - short wrinkles, processes length 2μm; Two antapical horns are significantly unequal in length (size), left larger, length 20 -35μm, right length 15-20μm, the end is blunt conical or short rod-shaped. The cingulum is obvious, marked by the concave at the ends of both lateral horns and the horizontal groove on the equator. Outer wall surface smooth or with low particles. The inner body outline is round-square or circular, usually width larger than length or equals to each other, the sides are straight or concave or conspicuously convex into the lateral horns. It is usually separated from the outer wall by a narrow outer cavity, In addition to the horns, the outer cavity on lateral sides is 0.5-2 μm wide. Archeopyle clear, intercalary, the outline of the trapezoid, length larger than width The operculum is completely separated and stored in place. Cyst length 130-170μm, width 137.5 - 172μm, the inner body length 85-105μm, width 87-110μm (measured 9); Holotype length 157.5μm, width 172μm, inner body length 105μm, width 110μm, apical horn length 22.5μm, left antapical horn length 30μ.m, right length 20μm, lateral horn length 27.5 μm. Discussion This species is characterized by lateral elongation of the cyst, width greater than the length or nearly equal, the good development of the lateral horns, the round inner body or convex into lateral horns etc. It is similar to Rhombodinium longimanum in appearance, But the former’s apical horn and two antapical horns are developed, while the latter is particularly developed on lateral horns, they are easy to distinguish.
Location and stratigraphy: Wucha County Basebulak; Wulagen fm.
Holotype: He Chengquan, 1991, pl.42, fig.3.
Age: middle Eocene.
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: The cyst is dorsal-ventral flattened, outline transversely elongated pentagonal, width larger than length or roughly equal to each other, sides concave. A conical apical horn is strong, 25-32μm long, the top circlar, with sparse particles or short spines; Both lateral horns are very developed, more or less cylindrical, 20-45μm long, tapering distally, end open or concave, often with simple decorations, such as short rod-thorns, coarse particles - short wrinkles, processes length 2μm; Two antapical horns are significantly unequal in length (size), left larger, length 20 -35μm, right length 15-20μm, the end is blunt conical or short rod-shaped. The cingulum is obvious, marked by the concave at the ends of both lateral horns and the horizontal groove on the equator. Outer wall surface smooth or with low particles. The inner body outline is round-square or circular, usually width larger than length or equals to each other, the sides are straight or concave or conspicuously convex into the lateral horns. It is usually separated from the outer wall by a narrow outer cavity, In addition to the horns, the outer cavity on lateral sides is 0.5-2 μm wide. Archeopyle clear, intercalary, the outline of the trapezoid, length larger than width The operculum is completely separated and stored in place. Cyst length 130-170μm, width 137.5 - 172μm, the inner body length 85-105μm, width 87-110μm (measured 9); Holotype length 157.5μm, width 172μm, inner body length 105μm, width 110μm, apical horn length 22.5μm, left antapical horn length 30μ.m, right length 20μm, lateral horn length 27.5 μm. Discussion This species is characterized by lateral elongation of the cyst, width greater than the length or nearly equal, the good development of the lateral horns, the round inner body or convex into lateral horns etc. It is similar to Rhombodinium longimanum in appearance, But the former’s apical horn and two antapical horns are developed, while the latter is particularly developed on lateral horns, they are easy to distinguish.
Location and stratigraphy: Wucha County Basebulak; Wulagen fm.