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Phthanoperidinium rhomboidale
Phthanoperidinium rhomboidale He Chengquan, 1991
Holotype: He Chengquan, 1991, pl.2, fig.12
Age: Late Eocene
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: the cyst is small, dorsal-ventral relatively flattened, outline nearly rhombus-oval, length larger than width. Upper cyst nearly bell-shape or triangle, with a short apical horn, papillary, 2.5μm long; lower cyst semicircular, no antapical horn. Cingulum shallow flat, equatorial position, ring, width about 5μm, decorated with fine ridges on the edge. Sulcus fuzzy. Cyst wall is thin, stratigraphy is vaguely visible, plates surface is smooth. Plates are marked by intercalary bands, intercalary bands are formed by two parallel ridges, about 2μm wide; the plates on epicyst are more vague than on the hypocyst, three precingular and postcingular plates and a hexagonal intercalary plate can be identified, the two antapical plates are clear, the apical area is small, the apical plates are not clear; no plates in the cingulum; paratabulation is expressed as x', 3a (?), 7 "(?), oc, 5'’', 2'’’’. Archeopyle is not shown. Length 38μm, width 30μm.
Note: Due to the small number of specimens studied, the plates of the upper cyst can not be accurately determined, and the complete paratabulation has to be studied further. This species is similar in morphology, size and paratabulation to the type species in the genus , But the intercalary bands of the former one consist of two parallel ridges rather than a single ridge, and lacking cingulum plates and so on.
Location and stratigraphy: Wuqia County Basebulak; member 2 and 3 in Basebulak formation.
Holotype: He Chengquan, 1991, pl.2, fig.12
Age: Late Eocene
Description from He Chengquan, 1991, translated by Suning Hou, 07-01-2019
Description: the cyst is small, dorsal-ventral relatively flattened, outline nearly rhombus-oval, length larger than width. Upper cyst nearly bell-shape or triangle, with a short apical horn, papillary, 2.5μm long; lower cyst semicircular, no antapical horn. Cingulum shallow flat, equatorial position, ring, width about 5μm, decorated with fine ridges on the edge. Sulcus fuzzy. Cyst wall is thin, stratigraphy is vaguely visible, plates surface is smooth. Plates are marked by intercalary bands, intercalary bands are formed by two parallel ridges, about 2μm wide; the plates on epicyst are more vague than on the hypocyst, three precingular and postcingular plates and a hexagonal intercalary plate can be identified, the two antapical plates are clear, the apical area is small, the apical plates are not clear; no plates in the cingulum; paratabulation is expressed as x', 3a (?), 7 "(?), oc, 5'’', 2'’’’. Archeopyle is not shown. Length 38μm, width 30μm.
Note: Due to the small number of specimens studied, the plates of the upper cyst can not be accurately determined, and the complete paratabulation has to be studied further. This species is similar in morphology, size and paratabulation to the type species in the genus , But the intercalary bands of the former one consist of two parallel ridges rather than a single ridge, and lacking cingulum plates and so on.
Location and stratigraphy: Wuqia County Basebulak; member 2 and 3 in Basebulak formation.