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Hystrichosphaeropsis complanata
From Fensome et al., 2019:
Hystrichosphaeropsis complanata Eisenack, 1965b, p.153–154, pl.14, figs.5a–b,6–7; pl.15, figs.5a–b; text-figs.2a–b,3. Holotype: Eisenack, 1965b, pl.14, figs.5a–b; text-figs.2a–b; Jan du Chêne et al., 1986a, pl.46, figs.2–3 and pl.48, figs.1–3. Age: Late Eocene–Early Oligocene.
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Original description (Eisenack, 1965) Translation PKB 2025:
Diagnosis: Central shell oval, granulated. Field boundaries defined by thin, fairly broad wing margins. Median margin particularly strongly developed, double-walled, tapering apically to a point, below which further ridges on the ventral and dorsal sides merge into the median margin. Antapically, several margins also converge to form an apparently downwardly open, approximately quadrilateral appendage that appears rounded in ventral or dorsal view. The dorsal lobe is well developed, fairly broad, and not subdivided below the left pyloma, which extends adjacent to it. Longitudinal fields broad, extending almost from the apex to the antapex. The archeopyle is subapical, rounded and trapezoidal.
Material and dimensions: 4 specimens. Type: central bowl 52 x 64 μm, total 70 x 112 μm, paratypoid: 48 x 62 or 66 x 92 μm, 3rd specimen on plate 15, Fig. 5: 52 x 61 or 68 x 86 μm.
Remarks: H. complanata is distinguished from H. ovum by the significantly better demarcation of the fields, the flattened median margin, and the rounded antapical attachment. The lateral edges of the archeopyle are separated from the ridges of the archeopyle by a distinct distance (as in Hystrichosphaera). The lower edge of the archeopyle extends into the girdle, so that only its border to the hypovalva retains the wing margin.
The double-walled nature of the median margin is evident at a crack below the apical tip (right) and also in the antapical region. It is assumed that the remaining ridges are also double-walled, arising from folds of an outer shell, but this is not evident in the specimens.
Hystrichosphaeropsis complanata Eisenack, 1965b, p.153–154, pl.14, figs.5a–b,6–7; pl.15, figs.5a–b; text-figs.2a–b,3. Holotype: Eisenack, 1965b, pl.14, figs.5a–b; text-figs.2a–b; Jan du Chêne et al., 1986a, pl.46, figs.2–3 and pl.48, figs.1–3. Age: Late Eocene–Early Oligocene.
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Original description (Eisenack, 1965) Translation PKB 2025:
Diagnosis: Central shell oval, granulated. Field boundaries defined by thin, fairly broad wing margins. Median margin particularly strongly developed, double-walled, tapering apically to a point, below which further ridges on the ventral and dorsal sides merge into the median margin. Antapically, several margins also converge to form an apparently downwardly open, approximately quadrilateral appendage that appears rounded in ventral or dorsal view. The dorsal lobe is well developed, fairly broad, and not subdivided below the left pyloma, which extends adjacent to it. Longitudinal fields broad, extending almost from the apex to the antapex. The archeopyle is subapical, rounded and trapezoidal.
Material and dimensions: 4 specimens. Type: central bowl 52 x 64 μm, total 70 x 112 μm, paratypoid: 48 x 62 or 66 x 92 μm, 3rd specimen on plate 15, Fig. 5: 52 x 61 or 68 x 86 μm.
Remarks: H. complanata is distinguished from H. ovum by the significantly better demarcation of the fields, the flattened median margin, and the rounded antapical attachment. The lateral edges of the archeopyle are separated from the ridges of the archeopyle by a distinct distance (as in Hystrichosphaera). The lower edge of the archeopyle extends into the girdle, so that only its border to the hypovalva retains the wing margin.
The double-walled nature of the median margin is evident at a crack below the apical tip (right) and also in the antapical region. It is assumed that the remaining ridges are also double-walled, arising from folds of an outer shell, but this is not evident in the specimens.