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Occisucysta hinzii
Occisucysta hinzii Below, 1984; emend. Jan du Chêne et al., 1986
Holotype: Below, 1984, pl.6, figs.7A-C; Jan du Chêne et al., 1986(a), pl.79, figs.7-9; Jan du Chêne et al., 1986(b), pl.10, figs.1-9
Locus typicus: Mazagan Plateau, off NW Africa
Stratum typicum: Middle-Late Aptian
Original diagnosis: Below, 1984, p.636
Large, proximate, two-layered, cornucavate, oval cyst with broad, pyramidal apical horn. Periphragma irregularly thickened to alveolate or forming a reticulum with muri and soli of variable width and shape. Very sparsely granulated. Endophragma thin, finely perforated. Paratabulation goniaulacacean ?PR, 4", 6"", Xc, as, ra, Is, rs, pv, 6""", 1"""". Parasutures marked by low, thick ridges that can expand to low septa. The hypocyst is distorted against the epicystal plate series so that 3"""/4""" parasuture is mid-dorsal. Intratabular pseudosutures occasionally present. Archeopyle 2P[2""-3""].
Dimensions. Holotype: length 78 µm, breadth 67 µm, length of endocyst 60 µm, height of septa up to 3 µm; other specimens: length 72-104 µm, length of endocyst 60-86 µm, width 60-84 µm, height of septa up to 4 µm.
Original description: Below, 1984, p.636
The large, two-layered cyst has a basically oval ambitus with an obvious, broad-based, hollow, equilateral pyramidal apical horn, which is positioned slightly off the anterior cyst pole and displaced in ventral direction (Plate 6, Fig. 8). The two cyst wall layers are closely attached, except at the apex where the outer layer forms the cornucavate apical protuberance. The periphragma is irregularly thickened and so gives rises to uneven, broad and high muri around soli of variable size and form (Fig. 6). Under light microscopy, the cyst wall appears alveolate. A few specimens show special thickenings of the muri to small intraparatabular pseudosutures, as described for Occisucysta brixii Below (1982), or thickenings of intrabular areas as shown for Occisucysta evittii (Dodekova, 1969) Gitmez, 1970 by Below (1982). General reduction of periphragmal structures is possible. Occasional specimens show nodes and tubercles as relicts of muri on a smooth or finely reticulated periphragma. The endophragma is smooth to finely reticulated. The cyst wall has low, thick parasutural ridges or--on a few specimens--narrow, perforated parasutural septa that are best developed around the antapex. The paratabulation is typically goniaulacacean. Preapical paraplates cannot be observed with absolute assurance, but there are faint lines on the apical horn that imply the existence of a top preapical 1PR and a second 2PR on the dorsal side of the horn. Four apical paraplates can be distinguished, a small, long 1", pentagonal 2" and 3" and the rhombic 4" that fills the angle between 5"" and 6"". The precingular series are trapezoidal or pentagonal and of equal size, except for the smaller 6"". The equatorially situated paracingulum is offset by its width at the parasulcus with its first and last paraplate bent posteriorly. The postcingular series begins with a small rectangular 1""". This is poorly separated from the parasulcus by a parasutural rib, but differs by its alveolate texture from the smooth Is. The postcingular series continues with the equilaterally triangular 2""" and the trapezoidal 3""" to 6""". The pv paraplate is very elongated and poorly defined against pr, ps, and Is, because of the absence of parasutural ridges. In the parasulcus it is possible to distinguish the elongated smooth Is, a long rs and an arrowshaped ps that is bent into a small antapical 1"""". Paraplate series of epicyst and hypocyst are distorted as in Cribroperidinium (Gocht, 1979; Below, 1981), so that the 3"""/4""" boundary is mid-dorsal. The archeopyle-type is 2P[2""-3""] but in some specimens paraplate 1"" and/ or 4"" are lost also.
Affinities:
Below, 1984, p.636: The irregularly thickened cyst wall with various shapes of muri and soli is unique among species of the genus Occisucysta.
Holotype: Below, 1984, pl.6, figs.7A-C; Jan du Chêne et al., 1986(a), pl.79, figs.7-9; Jan du Chêne et al., 1986(b), pl.10, figs.1-9
Locus typicus: Mazagan Plateau, off NW Africa
Stratum typicum: Middle-Late Aptian
Original diagnosis: Below, 1984, p.636
Large, proximate, two-layered, cornucavate, oval cyst with broad, pyramidal apical horn. Periphragma irregularly thickened to alveolate or forming a reticulum with muri and soli of variable width and shape. Very sparsely granulated. Endophragma thin, finely perforated. Paratabulation goniaulacacean ?PR, 4", 6"", Xc, as, ra, Is, rs, pv, 6""", 1"""". Parasutures marked by low, thick ridges that can expand to low septa. The hypocyst is distorted against the epicystal plate series so that 3"""/4""" parasuture is mid-dorsal. Intratabular pseudosutures occasionally present. Archeopyle 2P[2""-3""].
Dimensions. Holotype: length 78 µm, breadth 67 µm, length of endocyst 60 µm, height of septa up to 3 µm; other specimens: length 72-104 µm, length of endocyst 60-86 µm, width 60-84 µm, height of septa up to 4 µm.
Original description: Below, 1984, p.636
The large, two-layered cyst has a basically oval ambitus with an obvious, broad-based, hollow, equilateral pyramidal apical horn, which is positioned slightly off the anterior cyst pole and displaced in ventral direction (Plate 6, Fig. 8). The two cyst wall layers are closely attached, except at the apex where the outer layer forms the cornucavate apical protuberance. The periphragma is irregularly thickened and so gives rises to uneven, broad and high muri around soli of variable size and form (Fig. 6). Under light microscopy, the cyst wall appears alveolate. A few specimens show special thickenings of the muri to small intraparatabular pseudosutures, as described for Occisucysta brixii Below (1982), or thickenings of intrabular areas as shown for Occisucysta evittii (Dodekova, 1969) Gitmez, 1970 by Below (1982). General reduction of periphragmal structures is possible. Occasional specimens show nodes and tubercles as relicts of muri on a smooth or finely reticulated periphragma. The endophragma is smooth to finely reticulated. The cyst wall has low, thick parasutural ridges or--on a few specimens--narrow, perforated parasutural septa that are best developed around the antapex. The paratabulation is typically goniaulacacean. Preapical paraplates cannot be observed with absolute assurance, but there are faint lines on the apical horn that imply the existence of a top preapical 1PR and a second 2PR on the dorsal side of the horn. Four apical paraplates can be distinguished, a small, long 1", pentagonal 2" and 3" and the rhombic 4" that fills the angle between 5"" and 6"". The precingular series are trapezoidal or pentagonal and of equal size, except for the smaller 6"". The equatorially situated paracingulum is offset by its width at the parasulcus with its first and last paraplate bent posteriorly. The postcingular series begins with a small rectangular 1""". This is poorly separated from the parasulcus by a parasutural rib, but differs by its alveolate texture from the smooth Is. The postcingular series continues with the equilaterally triangular 2""" and the trapezoidal 3""" to 6""". The pv paraplate is very elongated and poorly defined against pr, ps, and Is, because of the absence of parasutural ridges. In the parasulcus it is possible to distinguish the elongated smooth Is, a long rs and an arrowshaped ps that is bent into a small antapical 1"""". Paraplate series of epicyst and hypocyst are distorted as in Cribroperidinium (Gocht, 1979; Below, 1981), so that the 3"""/4""" boundary is mid-dorsal. The archeopyle-type is 2P[2""-3""] but in some specimens paraplate 1"" and/ or 4"" are lost also.
Affinities:
Below, 1984, p.636: The irregularly thickened cyst wall with various shapes of muri and soli is unique among species of the genus Occisucysta.