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Impagidinium verrucosum
From Fensome et al., 2019:
Impagidinium verrucosum (Brideaux and McIntyre, 1975, p.30, pl.9, figs.1–8) Stover and Evitt, 1978, p.166. Holotype: Brideaux and McIntyre, 1975, pl.9, figs.1–4; Jan du Chêne et al., 1986a, pl.64, figs.16–19. Originally Pterodinium, subsequently (and now) Impagidinium. Age: middle Albian.
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Original description: [Brideaux and McIntyre, 1975]:
Pterodinium verrucosum sp. nov.
Plate 9, figures 1-8
Holotype. GSC No. 34150. Slide P851-4A, 39.8 x 118.8; Section CR14A-68, Horton River Formation, 37 to 45 feet (11.1 to 13.6 m); GSC 1oc. C-8535.
Total length, 62 u; total width, 61 ų (including sutural crests).
Diagnosis. Subeircular to ovoid cysts; two-layered wall, the periphragm bearing intratabular apiculate sculpture and forming high, thin, entire sutural crests, outlining a reflected tabul ation of 4', 6", 6c, 5"', 1"", 1p, 5s. Cingulum sinistral, displaced up to three cingular widths: sulcus with full tabulation, sinuous in outline. Archeopyle precingular, formed by loss of reflected plate 3", operculum detached.
Description. The periblast is sub circular or ovoid. The ratio of epitract to hypotract length is close to 1.0. The apex is rounded; the antapex is rounded or slightly flattened.
The cyst is two layered. The endophragm is thin, less than 1.0u thick in optical section, and smooth. The periphragm is as thin as the endophragm and forms the sutural crests. The two layers are in contact except along these crests. The periphragm bears apiculate sculpture in intrat abular regions that varies from grana to coni or irregular "wart-like" elements, from 1.0 to 3.0u high, typically 2.0 μ and 1.0 to 2.0 μ wide. The apiculate elements, as many as 40 per reflected plate, are concentrated in the central intrat abular regions, reduced or absent nearer the margins, and absent in the cingular region.
The archeopyle is precingular and formed by the loss of reflected plate 3". The operculum is detached.
The reflected tabulation pattern is determined as 4', 6", 6c, 5'", 1"", 1p, 5s, and is outlined by smooth, entire, sutural crests from 5 to 12 μ but
typically from 6 to 8 μ high. These crests often may be so folded or flatten ed, particularly in the apical region, as to obscure the details of tabulation. The crests are corroded occasionally and appear granulose or finely punctate.
The cingulum is outlined by cingular crests, similar in construction to the sutural crests. It is sinistral, 5-7 μ in width, and offset up to three cingular widths, but typically one and one -half to two widths. Six reflected cingular plates present. The sulcus follows a somewhat sinuous
course and exhibits a full complement of reflected sulcal plates. The reflected anterior sulcal plate is large; the reflected left sulcal plate is narrow, elongate and rectangular; the reflected right anterior sulcal and right sulcal plates are small by comparison and polygonal; the reflected posterior sulcal plate is larger and ovoid. A central elongate ovoid region is interpreted as the position of emplacement of the longitudinal flagellum of the thecal stage.
Dimensions. (37 measured specimens) - Periblast length, 58-80 μ; periblast width, 53-72 μ; endoblast length, 48-73 μ; endoblast width, 48-65 μ.
Occurrence. Horton River Formation (Middle Albian).
Impagidinium verrucosum (Brideaux and McIntyre, 1975, p.30, pl.9, figs.1–8) Stover and Evitt, 1978, p.166. Holotype: Brideaux and McIntyre, 1975, pl.9, figs.1–4; Jan du Chêne et al., 1986a, pl.64, figs.16–19. Originally Pterodinium, subsequently (and now) Impagidinium. Age: middle Albian.
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Original description: [Brideaux and McIntyre, 1975]:
Pterodinium verrucosum sp. nov.
Plate 9, figures 1-8
Holotype. GSC No. 34150. Slide P851-4A, 39.8 x 118.8; Section CR14A-68, Horton River Formation, 37 to 45 feet (11.1 to 13.6 m); GSC 1oc. C-8535.
Total length, 62 u; total width, 61 ų (including sutural crests).
Diagnosis. Subeircular to ovoid cysts; two-layered wall, the periphragm bearing intratabular apiculate sculpture and forming high, thin, entire sutural crests, outlining a reflected tabul ation of 4', 6", 6c, 5"', 1"", 1p, 5s. Cingulum sinistral, displaced up to three cingular widths: sulcus with full tabulation, sinuous in outline. Archeopyle precingular, formed by loss of reflected plate 3", operculum detached.
Description. The periblast is sub circular or ovoid. The ratio of epitract to hypotract length is close to 1.0. The apex is rounded; the antapex is rounded or slightly flattened.
The cyst is two layered. The endophragm is thin, less than 1.0u thick in optical section, and smooth. The periphragm is as thin as the endophragm and forms the sutural crests. The two layers are in contact except along these crests. The periphragm bears apiculate sculpture in intrat abular regions that varies from grana to coni or irregular "wart-like" elements, from 1.0 to 3.0u high, typically 2.0 μ and 1.0 to 2.0 μ wide. The apiculate elements, as many as 40 per reflected plate, are concentrated in the central intrat abular regions, reduced or absent nearer the margins, and absent in the cingular region.
The archeopyle is precingular and formed by the loss of reflected plate 3". The operculum is detached.
The reflected tabulation pattern is determined as 4', 6", 6c, 5'", 1"", 1p, 5s, and is outlined by smooth, entire, sutural crests from 5 to 12 μ but
typically from 6 to 8 μ high. These crests often may be so folded or flatten ed, particularly in the apical region, as to obscure the details of tabulation. The crests are corroded occasionally and appear granulose or finely punctate.
The cingulum is outlined by cingular crests, similar in construction to the sutural crests. It is sinistral, 5-7 μ in width, and offset up to three cingular widths, but typically one and one -half to two widths. Six reflected cingular plates present. The sulcus follows a somewhat sinuous
course and exhibits a full complement of reflected sulcal plates. The reflected anterior sulcal plate is large; the reflected left sulcal plate is narrow, elongate and rectangular; the reflected right anterior sulcal and right sulcal plates are small by comparison and polygonal; the reflected posterior sulcal plate is larger and ovoid. A central elongate ovoid region is interpreted as the position of emplacement of the longitudinal flagellum of the thecal stage.
Dimensions. (37 measured specimens) - Periblast length, 58-80 μ; periblast width, 53-72 μ; endoblast length, 48-73 μ; endoblast width, 48-65 μ.
Occurrence. Horton River Formation (Middle Albian).