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Deflandrea flounderensis
Deflandrea flounderensis Stover, 1974
Holotypus: Stover, 1974, pl.3, figs.1a-c
Locus typicus: Flounder-l well, Australia
Stratum typicum: Early Eocene
Original diagnosis: Stover, 1974, p.174-175
Periphragm outline triangularly elongate in dorsoventral view. Apical horn usually prominent and well defined; antapical horns less well defined and with the right horn commonly longer than the left, but not greatly so. On many specimens, the dorsal antapical part of the periphragm forms a skirt-like membrane between the horns (Plate 3, Figs. 1, 2) with a nearly straight antapical margin; however, in the same area on the ventral surface the margin of the periphragm is concave between the antapical horns. Lateral margins convex to straight and interrupted at about midheight by the ridges of the cingulum. Periphragm is ca. 1 Ám thick, in part smooth and in part finely granulate or conate with the sculpturing corresponding to plate areas. Tabulation peridinioid (4", 3a?, 7", 5""", 2""""). On most specimens the shapes and boundaries of the apical plates, except of 1", and the lateral plates are difficult to determine; whereas those for the medial plates are usually evident. Cingulum is marked by parallel transverse ridges, commonly with beaded crests, offset ventrally, undivided, and the floor of the ciagulum is smooth, or rarely with scattered grana. Sulcus generally poorly defined, and a comma-shaped scar is discernible on some specimens in the sulcus near its junction with the cingulum.
In dorso-ventral view, the outline of the endoblast is circular or nearly so. Endophragm is smooth, granulate, or coarsely vermiculate and 1-2.5 µm thick. Almost invariably the endophragm is thicker than the periphragm. Laterally, the periphragm and endophragm are close together and the clistance between the two walls increases apically and antapically.
The large intercalary archeopyle is broadly trapezoidal, about as wide as high, and with a relatively narrow apical end. The corresponding opening in the endophragm is as wide as in the periphragm, but the height is only about half as much. Operculum free.
Dimensions: Complete specimens are 112-166 µm long and 76-98 µm wide at the cingulum. Approximately three-quarters of the specimens are less than 135 µm long. The length to width ratio is 1:0.55-1:0.70 (mean 1:0.65). Maximum diameter of the endoblast is 60-88 µm and in about threequarters of the specimens, its width is greater than its length. Width of endophragmal opening is 37-46 µm and its length is 17-24 µm (width consistently about twice the length). Measurements based on 25 specimens.
Holotypus: Stover, 1974, pl.3, figs.1a-c
Locus typicus: Flounder-l well, Australia
Stratum typicum: Early Eocene
Original diagnosis: Stover, 1974, p.174-175
Periphragm outline triangularly elongate in dorsoventral view. Apical horn usually prominent and well defined; antapical horns less well defined and with the right horn commonly longer than the left, but not greatly so. On many specimens, the dorsal antapical part of the periphragm forms a skirt-like membrane between the horns (Plate 3, Figs. 1, 2) with a nearly straight antapical margin; however, in the same area on the ventral surface the margin of the periphragm is concave between the antapical horns. Lateral margins convex to straight and interrupted at about midheight by the ridges of the cingulum. Periphragm is ca. 1 Ám thick, in part smooth and in part finely granulate or conate with the sculpturing corresponding to plate areas. Tabulation peridinioid (4", 3a?, 7", 5""", 2""""). On most specimens the shapes and boundaries of the apical plates, except of 1", and the lateral plates are difficult to determine; whereas those for the medial plates are usually evident. Cingulum is marked by parallel transverse ridges, commonly with beaded crests, offset ventrally, undivided, and the floor of the ciagulum is smooth, or rarely with scattered grana. Sulcus generally poorly defined, and a comma-shaped scar is discernible on some specimens in the sulcus near its junction with the cingulum.
In dorso-ventral view, the outline of the endoblast is circular or nearly so. Endophragm is smooth, granulate, or coarsely vermiculate and 1-2.5 µm thick. Almost invariably the endophragm is thicker than the periphragm. Laterally, the periphragm and endophragm are close together and the clistance between the two walls increases apically and antapically.
The large intercalary archeopyle is broadly trapezoidal, about as wide as high, and with a relatively narrow apical end. The corresponding opening in the endophragm is as wide as in the periphragm, but the height is only about half as much. Operculum free.
Dimensions: Complete specimens are 112-166 µm long and 76-98 µm wide at the cingulum. Approximately three-quarters of the specimens are less than 135 µm long. The length to width ratio is 1:0.55-1:0.70 (mean 1:0.65). Maximum diameter of the endoblast is 60-88 µm and in about threequarters of the specimens, its width is greater than its length. Width of endophragmal opening is 37-46 µm and its length is 17-24 µm (width consistently about twice the length). Measurements based on 25 specimens.