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Rimosicysta kipperii
Rimosicysta kipperii Marshall 1989
Holotype. Marshall 1989: Plate 2, figs. 11 - 14
Locus typicus: Gippsland Basin, Southeastern Australia
Stratum typicum: Late Cretaceous
Description. Marshall 1989, p. 42, 44
Middorsal bulge weak to pronounced, frequently forms a flattened transverse fold. Dorsoventral outline elongate; lateral margins usually extended equatorially to form pronounced bulges. Hypocystal flanks usually markedly concave, occasionally nearly straight. Epicystal flanks nearly straight to convex. Apical margin truncated and with an irregular outline; antapical margin convex. Autophragm thins considerably and often split apart along apical margin, and frequently, along middle of hypocystal flanks. Autophragm 0.4-0.5 µm thick elsewhere; surface smooth, commonly strongly crumpled. Midventral surface bears a weak to pronounced longitudinal fold extending along much of the cyst length; fold often highest on hypocyst. Paracingulum occasionally suggested on dorsal surface by two parallel rounded ridges, ca. 6.0 µm apart, separated by a shallow groove. Intersection of groove with lateral margins marked by a rounded notch.
Size. Autocyst length 61(77)105 µm, width 48(62)75 µm: 22 specimens measured.
Comparison. Marshall 1989, p. 42, 44
This form is characterized by its truncated apical margin and gently curved outline that lacks pronounced projections. It has a similar general shape to some forms of Rimosicysta aspera, but the latter have a more angular outline. These are the only two species of the genus that have a distinctly truncated apical margin.
Occurrence. Kipper- 1 2839.0-2296.5 m.
Holotype. Marshall 1989: Plate 2, figs. 11 - 14
Locus typicus: Gippsland Basin, Southeastern Australia
Stratum typicum: Late Cretaceous
Description. Marshall 1989, p. 42, 44
Middorsal bulge weak to pronounced, frequently forms a flattened transverse fold. Dorsoventral outline elongate; lateral margins usually extended equatorially to form pronounced bulges. Hypocystal flanks usually markedly concave, occasionally nearly straight. Epicystal flanks nearly straight to convex. Apical margin truncated and with an irregular outline; antapical margin convex. Autophragm thins considerably and often split apart along apical margin, and frequently, along middle of hypocystal flanks. Autophragm 0.4-0.5 µm thick elsewhere; surface smooth, commonly strongly crumpled. Midventral surface bears a weak to pronounced longitudinal fold extending along much of the cyst length; fold often highest on hypocyst. Paracingulum occasionally suggested on dorsal surface by two parallel rounded ridges, ca. 6.0 µm apart, separated by a shallow groove. Intersection of groove with lateral margins marked by a rounded notch.
Size. Autocyst length 61(77)105 µm, width 48(62)75 µm: 22 specimens measured.
Comparison. Marshall 1989, p. 42, 44
This form is characterized by its truncated apical margin and gently curved outline that lacks pronounced projections. It has a similar general shape to some forms of Rimosicysta aspera, but the latter have a more angular outline. These are the only two species of the genus that have a distinctly truncated apical margin.
Occurrence. Kipper- 1 2839.0-2296.5 m.