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Quinquecuspis chinensis
Quinquecuspis chinensis He Chengquan and Sun Xuekun, 1991, p.292–293, pl.1, figs.3–4 ex He Chengquan et al., 2009, p.517–518. Holotype: He Chengquan and Sun Xuekun, 1991, p.292–293, pl.1, fig.3, designated by He Chengquan et al. (2009, p.518). This name was not validly published in He Chengquan and Sun Xuekun (1991) as no holotype was designated. Motile equivalent: Protoperidinium latissimum (Kofoid, 1907a) Balech, 1974, according to He Chengquan and Sun Xuekun (1991, p.292). Age: Quaternary.
Original description (He Chengquan and Sun Xuekun, 1991)
Description: Cyst proximate, pentagonal in outline, with more or less concave sides and a bulging equatorial region forming two lateral lobes (projections). Autophragm light brown in color, surface smooth. Epicyst nearly isosceles triangular with a conical apical horn. Hypocyst elongate and tapering toward antapex, antapical margin indented forming symmetrically two conical antapical horns. Paracingulum indicated only by the indentations at the lateral projections. Archaeopyle clear, intercalary, Type I2a, asymmetrical hexagonal in outline with three long and three very short sides. Operculum free or adherent.
Dimensions: Range: length 118.2-124.9 µm, width 93.6-94 µm; Holotype: 124.9 µm long, 94 µm wide.
Remarks: The present specimens are similar to the cysts of Protoperidinium latissimum (Kofoid) Balech in shape, structure and archeopyle. It is necessary to erect a new species to accommodate the specimens described here. This cyst species differs from Quinquecuspis concreta (Reid) Harland in possessing elongate hypocyst and in the absence of clear paracingulum.
According to Taylor (1976), the first apical plate of Protoperidinium latissimum varies in "ortho" "meta" and "para" forms. Matsuoka (1985, p. 60-61) stated further that P. latissimum should be basically assigned to the Ortho-Hexa group. Therefore, the new cyst species may be assigned to genus Quinquecuspis Harland.
Distribution: The Western Arabian Sea, the Woods Hole region of the U.S.A. and the coast of West Japan. Recent surface sediments.
Original description (He Chengquan and Sun Xuekun, 1991)
Description: Cyst proximate, pentagonal in outline, with more or less concave sides and a bulging equatorial region forming two lateral lobes (projections). Autophragm light brown in color, surface smooth. Epicyst nearly isosceles triangular with a conical apical horn. Hypocyst elongate and tapering toward antapex, antapical margin indented forming symmetrically two conical antapical horns. Paracingulum indicated only by the indentations at the lateral projections. Archaeopyle clear, intercalary, Type I2a, asymmetrical hexagonal in outline with three long and three very short sides. Operculum free or adherent.
Dimensions: Range: length 118.2-124.9 µm, width 93.6-94 µm; Holotype: 124.9 µm long, 94 µm wide.
Remarks: The present specimens are similar to the cysts of Protoperidinium latissimum (Kofoid) Balech in shape, structure and archeopyle. It is necessary to erect a new species to accommodate the specimens described here. This cyst species differs from Quinquecuspis concreta (Reid) Harland in possessing elongate hypocyst and in the absence of clear paracingulum.
According to Taylor (1976), the first apical plate of Protoperidinium latissimum varies in "ortho" "meta" and "para" forms. Matsuoka (1985, p. 60-61) stated further that P. latissimum should be basically assigned to the Ortho-Hexa group. Therefore, the new cyst species may be assigned to genus Quinquecuspis Harland.
Distribution: The Western Arabian Sea, the Woods Hole region of the U.S.A. and the coast of West Japan. Recent surface sediments.