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Canningia keiemensis
Canningia keiemensis, Louwye, 1997, p.149, pl.1, figs.1-6.
Holotype: Louwye, 1997, pl.1, figs.1-3,6.
Locus typicus and stratum typicum: Keiem, Weest Flanders, Belgium, well no. 36E135, -211.6 m, Turonian.
Occurrence: Keiem: -211.6 m, -204.0 m, -196.3 m (Turinian – Santonian); Nieuwkerke, -103.0 m (Santonian); Oostduinkerke well, -254.5 m (Cenomanian).
Age: latest Cenomanian-Santonian.
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Original description: [Louwye, 1997]:
Diagnosis:
The proximate cyst is bilayered. The autocyst is mostly subcircular with a small, rounded apical horn.
Two lateral protrusions at the paracingulum are developed and occasionally a faint, left antapical horn.
The autophragm is relatively thick (approx. 2 μm), scabrate to slightly granular. The cyst is lenticular-like the ventral surface is, in apical-antapical view, straight while the dorsal surface is convex. Solid, pillar-like protrusions (height max. 6 μm) and irregular septa cover the autophragm dorsally and laterally. Both type of processes occupy an intratabular and penitabular position, are fibrous and flare distally and proximally. They support a scabrate, perforate ectophragm. The unevenly distributed perforations of the ectophragm are circular or subcircular, ranging in diameter from 2 to 3 μm. The widest perforations occupy a penitabular position. The ectophragm displays a small but distinct apical horn, two rounded or sometimes slightly indented protrusions at the paracingulum and a left antapical protrusion. The right antapical protrusion is mostly absent or strongly reduced. The separation between the autophragm and ectophragm is more or less constant (about 5 μm), except at the antapex and paracingulum (max. separation 12 μm). The ectophragm is always absent from the ventral surface of the cyst, where occasionally some isolated septa or pillar-like protrusions occur.
Some characteristics of the gonyaulacean paratabulation: 3, 4 and 5 are well developed on the dorsal surface, the position of 2, 6 and 1i can be inferred from the accessory archeopyle parasutures.
The paracingulum is undivided and the postcingular paraplates III, IV and V are visible on the dorsal surface with IV large and trapezoidal. The parasulcal notch is offset.
The archeopyle is of the type (ta) with a slightly zigzag margin and clearly developed accessory archeopyle parasutures. The operculum is usually free.
Dimensions:
Holotype – total length 91 μm, length without operculum 65 μm, length of central body without operculum 57 μm, total width 81 μm, width of central body 67 μm.
Variation- total length 86-101 μm, length without operculum 54-78 μm, length of central body without operculum 54-68 μm, total width 64-87 μm, width of central body 54-71 μm. Number of specimens: 21.
Affinities/Comparison:
Canningia transitoria Stover & Helby, 1987 (Barremian – Early Aptian) differs by having an ectophragm that covers the cyst completely, a wider ectocoel and a less clearly but completely developed paratabulation. Canningia bassensis Marshall, 1990 (Campanian) is holocavate and has an ectophragm that covers the cyst completely although it is frequently discontinuous on the midventral surface. Furthermore, this species is not lenticular-like.
Holotype: Louwye, 1997, pl.1, figs.1-3,6.
Locus typicus and stratum typicum: Keiem, Weest Flanders, Belgium, well no. 36E135, -211.6 m, Turonian.
Occurrence: Keiem: -211.6 m, -204.0 m, -196.3 m (Turinian – Santonian); Nieuwkerke, -103.0 m (Santonian); Oostduinkerke well, -254.5 m (Cenomanian).
Age: latest Cenomanian-Santonian.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Louwye, 1997]:
Diagnosis:
The proximate cyst is bilayered. The autocyst is mostly subcircular with a small, rounded apical horn.
Two lateral protrusions at the paracingulum are developed and occasionally a faint, left antapical horn.
The autophragm is relatively thick (approx. 2 μm), scabrate to slightly granular. The cyst is lenticular-like the ventral surface is, in apical-antapical view, straight while the dorsal surface is convex. Solid, pillar-like protrusions (height max. 6 μm) and irregular septa cover the autophragm dorsally and laterally. Both type of processes occupy an intratabular and penitabular position, are fibrous and flare distally and proximally. They support a scabrate, perforate ectophragm. The unevenly distributed perforations of the ectophragm are circular or subcircular, ranging in diameter from 2 to 3 μm. The widest perforations occupy a penitabular position. The ectophragm displays a small but distinct apical horn, two rounded or sometimes slightly indented protrusions at the paracingulum and a left antapical protrusion. The right antapical protrusion is mostly absent or strongly reduced. The separation between the autophragm and ectophragm is more or less constant (about 5 μm), except at the antapex and paracingulum (max. separation 12 μm). The ectophragm is always absent from the ventral surface of the cyst, where occasionally some isolated septa or pillar-like protrusions occur.
Some characteristics of the gonyaulacean paratabulation: 3, 4 and 5 are well developed on the dorsal surface, the position of 2, 6 and 1i can be inferred from the accessory archeopyle parasutures.
The paracingulum is undivided and the postcingular paraplates III, IV and V are visible on the dorsal surface with IV large and trapezoidal. The parasulcal notch is offset.
The archeopyle is of the type (ta) with a slightly zigzag margin and clearly developed accessory archeopyle parasutures. The operculum is usually free.
Dimensions:
Holotype – total length 91 μm, length without operculum 65 μm, length of central body without operculum 57 μm, total width 81 μm, width of central body 67 μm.
Variation- total length 86-101 μm, length without operculum 54-78 μm, length of central body without operculum 54-68 μm, total width 64-87 μm, width of central body 54-71 μm. Number of specimens: 21.
Affinities/Comparison:
Canningia transitoria Stover & Helby, 1987 (Barremian – Early Aptian) differs by having an ectophragm that covers the cyst completely, a wider ectocoel and a less clearly but completely developed paratabulation. Canningia bassensis Marshall, 1990 (Campanian) is holocavate and has an ectophragm that covers the cyst completely although it is frequently discontinuous on the midventral surface. Furthermore, this species is not lenticular-like.