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Dinopterygium verriculum
Dinopterygium verriculum Piasecki, 1980
Now Gramocysta. Originally Dinopterygium, subsequently Heteraulacacysta, thirdly (and now) Gramocysta.
Holotype: pl.1, figs.7-8
Age: Late Miocene
Original description: Pisaecki, 1980, p. 66-67
Dinopterygium verriculum sp. nov. PL 1, fig. 4-8, PI. 5, fig. 5-6.
Diagnosis: A species of Dinopterygium with thin, hyaline wall layers, separated by pillars or low membranes, forming a reticulate pattern. The outer wall layer may form low fenestrated parasutural membranes, but no large and extending cingular membranes are present. The archaeopyle is epicystal; Type tA+tPa.
Description: A proximate to proximochorate cyst, with a rounded to pentagonal shape in aequatorial view, and ovoidal shape with the parasulcal area slightly grooved in polar view. The cyst wall is differentiated into three units. Endophragma and periphragma are thin and hyaline, and separated by short "processes" or low membranes. A spongeous tissue occurs very seldom. The middle wall unit form a reticulate pattern with varying mesh size. The surface of the cyst is smooth or finely punctate. The paratabulation may be determined from variations in the structure between endo- < and periphragma or from parasutural membranes formed by upfolding of the periphragma. The parasutural membranes on the surface of the cyst are 1 to 2 (xm high, but occasionally up to 6 [xm high. They are densely perforated. The paracingulum and parasulcus are not differentiated into paraplates except for paraplate ps. The paratabulation formula is determined to be (3(4)', 6", ?c, 5'", ps, Ip, 1""). The apical paraplates have only been observed on one occasion, because the epicyst is disintergrated into single paraplates during archaeopyle formation, and only excysted specimens have been found. The paracingulum is slightly hélicoïdal, and the parasulcus is slightly grooved. The position of paraplates ps and Ip and the shepe of 1" " indicate a pyrodinium-type of tabulation (Evitt, 1976). The archaeopyle is epicystal and the archaeopyle formula is tA+tPa. Varying numbers of precingular paraplates may remain attached to the hypocyst after the archaeopyle formation. The parasulcus form a minor sulcal flap at the margin of. the hypocyst.
Discussion: Dinopterygium verriculum sp. nov. differs from other species of the genus by the wall structure and by the absence of a single compound operculum.
Holotype: PI. 1, fig. 7-8. Size: length 63 µm excl. apical area, breadth 77 (µm. MGUH 14958. Size variation: (n=25) length 51 (56) 6 µm excl. apical area, breadth 50 (62) 77 µm.
Type locality and type stratum: Danmark, Gram, Gram boring (DGU file 141 423), 20.0—5.0 m below surface, Gram Formation. Stratigraphical range: Upper Miocene, Dinopterygium verriculum Zone.
Supplemental description: Lund and Lund-Christensen, 1990, p. 34
The holocavate wall is made up by an inner layer (autophragm) and an outher layer (extophragm) separated by platy structures standing perpendicular between these two layers. The platy structures form a reticulate or microreticulate pattern. The specimen shown on Plate 8, figs. Ia-b is similar to the holotype. Most specimens have lost all precingular paraplates and are seen in apicalantapical view as the specimen on plate 8, fig. 2.
Now Gramocysta. Originally Dinopterygium, subsequently Heteraulacacysta, thirdly (and now) Gramocysta.
Holotype: pl.1, figs.7-8
Age: Late Miocene
Original description: Pisaecki, 1980, p. 66-67
Dinopterygium verriculum sp. nov. PL 1, fig. 4-8, PI. 5, fig. 5-6.
Diagnosis: A species of Dinopterygium with thin, hyaline wall layers, separated by pillars or low membranes, forming a reticulate pattern. The outer wall layer may form low fenestrated parasutural membranes, but no large and extending cingular membranes are present. The archaeopyle is epicystal; Type tA+tPa.
Description: A proximate to proximochorate cyst, with a rounded to pentagonal shape in aequatorial view, and ovoidal shape with the parasulcal area slightly grooved in polar view. The cyst wall is differentiated into three units. Endophragma and periphragma are thin and hyaline, and separated by short "processes" or low membranes. A spongeous tissue occurs very seldom. The middle wall unit form a reticulate pattern with varying mesh size. The surface of the cyst is smooth or finely punctate. The paratabulation may be determined from variations in the structure between endo- < and periphragma or from parasutural membranes formed by upfolding of the periphragma. The parasutural membranes on the surface of the cyst are 1 to 2 (xm high, but occasionally up to 6 [xm high. They are densely perforated. The paracingulum and parasulcus are not differentiated into paraplates except for paraplate ps. The paratabulation formula is determined to be (3(4)', 6", ?c, 5'", ps, Ip, 1""). The apical paraplates have only been observed on one occasion, because the epicyst is disintergrated into single paraplates during archaeopyle formation, and only excysted specimens have been found. The paracingulum is slightly hélicoïdal, and the parasulcus is slightly grooved. The position of paraplates ps and Ip and the shepe of 1" " indicate a pyrodinium-type of tabulation (Evitt, 1976). The archaeopyle is epicystal and the archaeopyle formula is tA+tPa. Varying numbers of precingular paraplates may remain attached to the hypocyst after the archaeopyle formation. The parasulcus form a minor sulcal flap at the margin of. the hypocyst.
Discussion: Dinopterygium verriculum sp. nov. differs from other species of the genus by the wall structure and by the absence of a single compound operculum.
Holotype: PI. 1, fig. 7-8. Size: length 63 µm excl. apical area, breadth 77 (µm. MGUH 14958. Size variation: (n=25) length 51 (56) 6 µm excl. apical area, breadth 50 (62) 77 µm.
Type locality and type stratum: Danmark, Gram, Gram boring (DGU file 141 423), 20.0—5.0 m below surface, Gram Formation. Stratigraphical range: Upper Miocene, Dinopterygium verriculum Zone.
Supplemental description: Lund and Lund-Christensen, 1990, p. 34
The holocavate wall is made up by an inner layer (autophragm) and an outher layer (extophragm) separated by platy structures standing perpendicular between these two layers. The platy structures form a reticulate or microreticulate pattern. The specimen shown on Plate 8, figs. Ia-b is similar to the holotype. Most specimens have lost all precingular paraplates and are seen in apicalantapical view as the specimen on plate 8, fig. 2.