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Membranophoridium bilobatum
Membranophoridium bilobatum Michoux, 1985
Holotype: Michoux, 1985, pl.3, fig.9
Age: Middle Eocene
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Original description: [Michoux, 1985] (translated from French):
Membranophoridium bilobatum n. sp.
(Pl. 2, fig. 8, 11; PI. 3, fig. 9, 10)
Holotype: Slide N1-4, coordinates P40-4.
Origin of the name: From the two antopic lobes formed by the periphragm.
Type locality: Tuilerie de Nousse.
Diagnosis: Proximochorate cyst, lenticular in shape, flattened dorsoventrally. The periphragm is adjacent to the endophragm except at the periphery of the cyst where it forms two adjacent membranes, one ventral, the other dorsal.
Description: The central body of the cyst has a lenticular outline, sometimes modified by a slight antapical protuberance. The cyst is flattened dorsoventrally. The operculum, when in place, shows a more prominent protuberance (PI. 2, Fig. 11). The anterior edge of the central body is indented by notches that correspond to the boundaries of the precingulate plates and form the only trace of tabulation. The sulcal notch is shifted to the left. The endophragm is slightly granular and thicker than the periphragm. The latter is thin and pleated. It forms two adjacent membranes, one dorsal, the other ventral, whose development is restricted to the periphery of the cyst. They are low, wavy, and sometimes perforated. The dorsal membrane is continuous, while the ventral membrane is interrupted antapically and forms two separate lobes. These lobes are themselves sometimes perforated, as shown in Figure 9, Plate 3.
Dimensions: Diameter of central body: 68 (80) 95 μm; Height of antapic lobes: up to 20 μm; 10 specimens measured.
Discussion: This species differs from Membranophoridium aspinatum GERLACH, 1961 by the less extensive development of the peripheral membrane. The antapic lobes are closer together. The membrane is more continuous in M. bilobatum, its contour is less sinuous, and it encroaches less on the central part of the cyst.
Holotype: Michoux, 1985, pl.3, fig.9
Age: Middle Eocene
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Original description: [Michoux, 1985] (translated from French):
Membranophoridium bilobatum n. sp.
(Pl. 2, fig. 8, 11; PI. 3, fig. 9, 10)
Holotype: Slide N1-4, coordinates P40-4.
Origin of the name: From the two antopic lobes formed by the periphragm.
Type locality: Tuilerie de Nousse.
Diagnosis: Proximochorate cyst, lenticular in shape, flattened dorsoventrally. The periphragm is adjacent to the endophragm except at the periphery of the cyst where it forms two adjacent membranes, one ventral, the other dorsal.
Description: The central body of the cyst has a lenticular outline, sometimes modified by a slight antapical protuberance. The cyst is flattened dorsoventrally. The operculum, when in place, shows a more prominent protuberance (PI. 2, Fig. 11). The anterior edge of the central body is indented by notches that correspond to the boundaries of the precingulate plates and form the only trace of tabulation. The sulcal notch is shifted to the left. The endophragm is slightly granular and thicker than the periphragm. The latter is thin and pleated. It forms two adjacent membranes, one dorsal, the other ventral, whose development is restricted to the periphery of the cyst. They are low, wavy, and sometimes perforated. The dorsal membrane is continuous, while the ventral membrane is interrupted antapically and forms two separate lobes. These lobes are themselves sometimes perforated, as shown in Figure 9, Plate 3.
Dimensions: Diameter of central body: 68 (80) 95 μm; Height of antapic lobes: up to 20 μm; 10 specimens measured.
Discussion: This species differs from Membranophoridium aspinatum GERLACH, 1961 by the less extensive development of the peripheral membrane. The antapic lobes are closer together. The membrane is more continuous in M. bilobatum, its contour is less sinuous, and it encroaches less on the central part of the cyst.