Back
Glaphyrocysta pseudoreticulata
Glaphyrocysta pseudoreticulata, Vieira, M. et al., 2018, p. 189
Holotype: Vieira, M. et al., 2018, Plate 4, figure 1
Type locality: southern part of the Ormen Lange field (Norway) over the Danian-aged reservoir
Local stratigraphical range: Danian (Early Paleocene)
Original description: Vieira, M. et al., 2018:
Diagnosis:
Proximochorate to chorate cysts, central body usually dorsoventrally flattened with circular to sub-circular outline and smooth to finely granulate surface, with a single small lobe at the base sometimes observed.
Processes: restricted to the peripheral zone of the cyst body. These processes are joined proximally in linear or arcuate groups and usually connected distally by irregularly broad perforate to trabeculae termination; the outer edge of the trabeculae are serrate to finally denticulate. The processes have fenestrate to reticulate terminations which expand and unite with arched-like trabeculae of variable width.
The ornament of this cyst consists of a mixture of thin delicate and membraneous processes. These are mostly isolated, although a few adjacent processes arise from low, short proximal ridges and are restricted to the peripheral zone of the cyst body, variable in breadth, branched and expanded distally. The majority are united by membranous trabeculae of variable width, with most of the mid-ventral and mid-dorsal surface areas being devoid of processes. Isolated processes are fine but well distinguished and joined in a fine network of projections.
Archeopyle: apical, tetratabular with well defined (tA) and with a typical ‘zig-zag’ margin, operculum free.
Dimensions:
Holotype: central body length 72 µm, width 100.5 µm (without operculum); length 81 µm, width 130 µm (with processes), length of processes 39 µm
20 specimens measured: Central body length 48 (64) 78 µm, width 59 (76) 97 µm (without operculum); central body 82 (104.5) 144 µm
(with processes), length of processes 24 (35.5) 48 µm.
Affinities/Comparison:
Glaphyrocysta exuberans (Deflandre & Cookson 1955) Stover & Evitt 1978 closely resembles the present species, but differs in having more robust processes with a variably fenestrate membrane. Glaphyrocysta semitecta (Bujak 1980) Lentin & Williams 1981 differs in lacking a fenestrate process stem and having a highly perforated membrane. When compared with the Late Maastrichtian–Danian-type Glaphyrocysta perforata described by Hultberg & Malmgren (1985), it can be suggested that the processes do not fuse in a perforate periphragm, which
in G. perforata distally changes into a homogeneous, almost non-perforate periphragm with no indication of the processes terminating with an irregular margin.
Holotype: Vieira, M. et al., 2018, Plate 4, figure 1
Type locality: southern part of the Ormen Lange field (Norway) over the Danian-aged reservoir
Local stratigraphical range: Danian (Early Paleocene)
Original description: Vieira, M. et al., 2018:
Diagnosis:
Proximochorate to chorate cysts, central body usually dorsoventrally flattened with circular to sub-circular outline and smooth to finely granulate surface, with a single small lobe at the base sometimes observed.
Processes: restricted to the peripheral zone of the cyst body. These processes are joined proximally in linear or arcuate groups and usually connected distally by irregularly broad perforate to trabeculae termination; the outer edge of the trabeculae are serrate to finally denticulate. The processes have fenestrate to reticulate terminations which expand and unite with arched-like trabeculae of variable width.
The ornament of this cyst consists of a mixture of thin delicate and membraneous processes. These are mostly isolated, although a few adjacent processes arise from low, short proximal ridges and are restricted to the peripheral zone of the cyst body, variable in breadth, branched and expanded distally. The majority are united by membranous trabeculae of variable width, with most of the mid-ventral and mid-dorsal surface areas being devoid of processes. Isolated processes are fine but well distinguished and joined in a fine network of projections.
Archeopyle: apical, tetratabular with well defined (tA) and with a typical ‘zig-zag’ margin, operculum free.
Dimensions:
Holotype: central body length 72 µm, width 100.5 µm (without operculum); length 81 µm, width 130 µm (with processes), length of processes 39 µm
20 specimens measured: Central body length 48 (64) 78 µm, width 59 (76) 97 µm (without operculum); central body 82 (104.5) 144 µm
(with processes), length of processes 24 (35.5) 48 µm.
Affinities/Comparison:
Glaphyrocysta exuberans (Deflandre & Cookson 1955) Stover & Evitt 1978 closely resembles the present species, but differs in having more robust processes with a variably fenestrate membrane. Glaphyrocysta semitecta (Bujak 1980) Lentin & Williams 1981 differs in lacking a fenestrate process stem and having a highly perforated membrane. When compared with the Late Maastrichtian–Danian-type Glaphyrocysta perforata described by Hultberg & Malmgren (1985), it can be suggested that the processes do not fuse in a perforate periphragm, which
in G. perforata distally changes into a homogeneous, almost non-perforate periphragm with no indication of the processes terminating with an irregular margin.