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Isabelidinium amphiatum
Isabelidinium? amphiatum (McIntyre, 1975) Lentin and Williams, 1977
Originally Deflandrea, subsequently (and now) Isabelidinium?. See also Alterbia (combination illegitimate) and Isabelia (combination illegitimate).
At the time of the transfer, Lentin and Williams, 1977, questionably included this species in Isabelidinium.
Yun, 1981, transferred this species to Alterbia Lentin and Williams, 1976. Lentin and Williams, 1985, retained it in Isabelidinium.
Holotypus: McIntyre, 1975, pl. 2, figs.5,6
Locus typicus: Horton River, N. W. T., Canada
Stratum typicum: Campanian-Maastrichtian
Original diagnosis: McIntyre, 1975, p.65: Deflandrea amphiata
Cyst cavate, approximately pentagonal in dorsoventral view, dorsoventrally flattened and convex in equatorial region. The epitract and hypotract are of equal size and the periblast is often folded in the equatorial region. On the epitract the periblast tapers to a short apical horn which often has a short papilla. Periblast usually has slight lateral bulges opposite top of archeopyle. The left antapical horn is a short, rounded bulge and is only slightly larger than the right antapical horn, which is usually indicated as a rounded right angle in the periblast. Cingulum not normally present, but some specimens have faint indications of a cingulum (Pl. 2, fig. 7). A wide sulcus is very indistinctly indicated on some specimens by longitudinal folds (Pl. 2, fig. 8). The very large intercalary (2a) archeopyle occupies much of the dorsal surface of the epitract and extends almost to the cingulum on the equatorial region. Archeopyle hexagonal; operculum usually attached at posterior margin. No other indications of tabulation are visible. The endoblast is usually short and extends to or nearly to the periblast lateral margin in the equatorial region. Endoblast often folded and often rather indistinct. Endophragm smooth and less than 1/2 Ám thick. Periphragm 1 Ám or less thick and smooth to finely scabrate and sometimes partly striate. Large apical and antapical pericoels are present.
Dimensions: Holotype, 113 Ám long, 60 Ám wide; endoblast, 28 Ám long; range, 99-133 Ám long, 53-67 Ám wide endoblast, 28-42 Ám long.
Originally Deflandrea, subsequently (and now) Isabelidinium?. See also Alterbia (combination illegitimate) and Isabelia (combination illegitimate).
At the time of the transfer, Lentin and Williams, 1977, questionably included this species in Isabelidinium.
Yun, 1981, transferred this species to Alterbia Lentin and Williams, 1976. Lentin and Williams, 1985, retained it in Isabelidinium.
Holotypus: McIntyre, 1975, pl. 2, figs.5,6
Locus typicus: Horton River, N. W. T., Canada
Stratum typicum: Campanian-Maastrichtian
Original diagnosis: McIntyre, 1975, p.65: Deflandrea amphiata
Cyst cavate, approximately pentagonal in dorsoventral view, dorsoventrally flattened and convex in equatorial region. The epitract and hypotract are of equal size and the periblast is often folded in the equatorial region. On the epitract the periblast tapers to a short apical horn which often has a short papilla. Periblast usually has slight lateral bulges opposite top of archeopyle. The left antapical horn is a short, rounded bulge and is only slightly larger than the right antapical horn, which is usually indicated as a rounded right angle in the periblast. Cingulum not normally present, but some specimens have faint indications of a cingulum (Pl. 2, fig. 7). A wide sulcus is very indistinctly indicated on some specimens by longitudinal folds (Pl. 2, fig. 8). The very large intercalary (2a) archeopyle occupies much of the dorsal surface of the epitract and extends almost to the cingulum on the equatorial region. Archeopyle hexagonal; operculum usually attached at posterior margin. No other indications of tabulation are visible. The endoblast is usually short and extends to or nearly to the periblast lateral margin in the equatorial region. Endoblast often folded and often rather indistinct. Endophragm smooth and less than 1/2 Ám thick. Periphragm 1 Ám or less thick and smooth to finely scabrate and sometimes partly striate. Large apical and antapical pericoels are present.
Dimensions: Holotype, 113 Ám long, 60 Ám wide; endoblast, 28 Ám long; range, 99-133 Ám long, 53-67 Ám wide endoblast, 28-42 Ám long.