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Pterodinium mamounia
Pterodinium mamounia Below, 1981
Holotype: Below, 1981, pl.7, figs.9a-d and Jan du Chêne et al., 1986, pl.87
fig.7; Fensome et al., 1991, figs.1-4 - p.667
Locus typicus: North-northeast of Adouz, southwest Morocco
Stratum typicum: Aptian: Gargasian
Translation Below, 1981: Femsome, 1991, p. 668-669
Original diagnosis: Below, 1981, p. 116
Chorate, tabulate cyst with a smooth, two-layered membrane. The endophragm forms the central body, which is rounded-rhombic to elongate-oval in outline and surmounted by a hump-like apical appendage. The periphragm develops high, parasutural septa with smooth or denticulate margins. The length of the septa increases from the equator to the poles; consequently, the entire cyst assumes an approximately rectangular outline. Paracingulum consisting of six plates, strongly spiral. Parasulcus very weakly sigmoidal. Archeopyle of type P(3""). Paratabulation
4", 6", 6c, 6""", pc, 1"""", 0-1ps.
Original description: Below, 1981, p. 116-117
The central body is elongate-pentagonal, rhomboidal, elongate-ovoid to oval in outline. The apical pole is slightly pointed and bears a low, hump-like appendage, in contrast to the rounded or flattened antapex. The epicyst and hypocyst are equal in size.
The brick-like shape of the cyst is clearly influenced by the variable longitudinal development of the septa. The parasutural membranes are lowest equatorially and become increasingly higher towards the apex and antapex in the precingular and postcingular regions. In this way they compensate approximately for the reduction of the diameter of the central body between the equator and poles; consequently, the cyst width remains more or less the same. The septa between the apical paraplates do not show this development. Their height at the apex is reduced to a minimum; consequently, the central body, with its apical appendage, may extend only slightly beyond the rectangular cyst outline. At triple junctions of the parasutures, the septa do not always connect completely from their proximal to distal ends along the direction normal to the central body. The contact is developed only proximally, whereas distally the septa are slightly curved, enclosing a funnel-like cavity that is triangular in outline ([Below, 1981a] pl.7, fig.9a; pl.14,15; text-fig.77a). This phenomenon is the rule at the junctions of the septa marking the postcingular paraplates and the antapical 1"""".
The high membranes, with their smooth or finely denticulate distal margins, divide the central body into paraplates. In this way, they follow the scheme determined for Pterodinium premnos Duxbury 1980 ([Below 1981a] text-fig.76). The apical paraplate series consists of a long, narrow 1", separated from an equally narrow 4" merely by a low ridge, and polygonal 2" and 3". In contrast to precingulars 1"-5", paraplate 6"" is strongly reduced in size and often only indistinctly separated from the parasulcus due to the commonly degenerate parasuture. The hypocyst is divided into a narrow 1""", which is usually only indistinctly separated from ls, a triangular 2""", trapezoidal 3""" to 6""", a square 1"""" and a small paraplate pc.
The paracingulum is subdivided into six plates and is strongly helicoidal. The parasulcus is offset by approximately twice the width of the transverse furrow. On the hypocyst, the longitudinal furrow extends almost to the antapex, unless its posterior part is separated to form paraplate ps. In contrast, the parasulcus extends only slightly onto the epicyst in the form of the small as [anterior sulcal].
Holotype: Below, 1981, pl.7, figs.9a-d and Jan du Chêne et al., 1986, pl.87
fig.7; Fensome et al., 1991, figs.1-4 - p.667
Locus typicus: North-northeast of Adouz, southwest Morocco
Stratum typicum: Aptian: Gargasian
Translation Below, 1981: Femsome, 1991, p. 668-669
Original diagnosis: Below, 1981, p. 116
Chorate, tabulate cyst with a smooth, two-layered membrane. The endophragm forms the central body, which is rounded-rhombic to elongate-oval in outline and surmounted by a hump-like apical appendage. The periphragm develops high, parasutural septa with smooth or denticulate margins. The length of the septa increases from the equator to the poles; consequently, the entire cyst assumes an approximately rectangular outline. Paracingulum consisting of six plates, strongly spiral. Parasulcus very weakly sigmoidal. Archeopyle of type P(3""). Paratabulation
4", 6", 6c, 6""", pc, 1"""", 0-1ps.
Original description: Below, 1981, p. 116-117
The central body is elongate-pentagonal, rhomboidal, elongate-ovoid to oval in outline. The apical pole is slightly pointed and bears a low, hump-like appendage, in contrast to the rounded or flattened antapex. The epicyst and hypocyst are equal in size.
The brick-like shape of the cyst is clearly influenced by the variable longitudinal development of the septa. The parasutural membranes are lowest equatorially and become increasingly higher towards the apex and antapex in the precingular and postcingular regions. In this way they compensate approximately for the reduction of the diameter of the central body between the equator and poles; consequently, the cyst width remains more or less the same. The septa between the apical paraplates do not show this development. Their height at the apex is reduced to a minimum; consequently, the central body, with its apical appendage, may extend only slightly beyond the rectangular cyst outline. At triple junctions of the parasutures, the septa do not always connect completely from their proximal to distal ends along the direction normal to the central body. The contact is developed only proximally, whereas distally the septa are slightly curved, enclosing a funnel-like cavity that is triangular in outline ([Below, 1981a] pl.7, fig.9a; pl.14,15; text-fig.77a). This phenomenon is the rule at the junctions of the septa marking the postcingular paraplates and the antapical 1"""".
The high membranes, with their smooth or finely denticulate distal margins, divide the central body into paraplates. In this way, they follow the scheme determined for Pterodinium premnos Duxbury 1980 ([Below 1981a] text-fig.76). The apical paraplate series consists of a long, narrow 1", separated from an equally narrow 4" merely by a low ridge, and polygonal 2" and 3". In contrast to precingulars 1"-5", paraplate 6"" is strongly reduced in size and often only indistinctly separated from the parasulcus due to the commonly degenerate parasuture. The hypocyst is divided into a narrow 1""", which is usually only indistinctly separated from ls, a triangular 2""", trapezoidal 3""" to 6""", a square 1"""" and a small paraplate pc.
The paracingulum is subdivided into six plates and is strongly helicoidal. The parasulcus is offset by approximately twice the width of the transverse furrow. On the hypocyst, the longitudinal furrow extends almost to the antapex, unless its posterior part is separated to form paraplate ps. In contrast, the parasulcus extends only slightly onto the epicyst in the form of the small as [anterior sulcal].