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Cerodinium medcalfii
Cerodinium medcalfi, (Stover, 1974), Lentin and Williams, 1987
Originally Deflandrea medcalfii, subsequently Deflandrea dartmooria ssp. medcalfii, thirdly (and now) Cerodinium medcalfii; see also Ceratiopsis medcalfii (combinahon illegitimate).
Holotype: Stover, 1974, pl.3, figs.3a-c
Locus typicus: Point Margaret, Gellibrand River, Australia
Stratum typicum: Middle Paleocene
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Original description as Deflandrea medcalfii: [Stover, 1974, p. 175]:
Diagnosis:
Cysts are tricornate with an elongate, tapered apical horn and prominent antapical horns of about equal size and with narrowly rounded or pointed tips.
Antapical horns separated by a broad medial concavity. Lateral margins of periphragm are gently convex anterior to the cingulum, and straight to slightly concave posterior to the cingulum.
Periphragm less than 1 µm thick and clear except for areas with small coni.
The species has a typical peridinioid tabulation of 4", 3a?, 7", 5""", 2"""" with the size, shape, and position of the plates represented by the conate areas.
Cingulum defined by transverse parallel ridges about 1 µm high, 5-7 µm apart, and fringed with coni, denticles, or spinules. On some specimens the cingulum is subdivided by longitudinal ridges and its floor is smooth or bears scattered coni.
Sulcal margins generally indefinite, and on most specimens, a hook-shaped scar occurs in the sulcus near its junction with the cingulum and generally a little right of centre.
Endoblast is comparatively large, broadly elliptical to ovoid in dorsoventral view, generally wider than long although on some specimens the reverse is true, and located about centrally with respect to the periphragm. Endoblast configuration approximates that of the periblast laterally but deviates apically and antapically. Endophragm is smooth and ca. 0.5 µm thick.
Archeopyle intercalary, large, irregularly hexagonal in outline, and with a narrower apical than antapical margin. Opening in endophragm corresponds with that in the periphragm. Operculum free.
Dimensions:
Length of periphragm is 106-140 µm, width of periphragm is 68-75 µm and the specimens have a length width ratio between 1:0.53 and 1:0.73 (mean 1:0.64). Length of endophragm is 53-70 µm, width 58-76 µm. Apical horn is 22-34 µm long; antapical horns 20-36 µm long.
Measurements based on 12 complete specimens.
Originally Deflandrea medcalfii, subsequently Deflandrea dartmooria ssp. medcalfii, thirdly (and now) Cerodinium medcalfii; see also Ceratiopsis medcalfii (combinahon illegitimate).
Holotype: Stover, 1974, pl.3, figs.3a-c
Locus typicus: Point Margaret, Gellibrand River, Australia
Stratum typicum: Middle Paleocene
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Original description as Deflandrea medcalfii: [Stover, 1974, p. 175]:
Diagnosis:
Cysts are tricornate with an elongate, tapered apical horn and prominent antapical horns of about equal size and with narrowly rounded or pointed tips.
Antapical horns separated by a broad medial concavity. Lateral margins of periphragm are gently convex anterior to the cingulum, and straight to slightly concave posterior to the cingulum.
Periphragm less than 1 µm thick and clear except for areas with small coni.
The species has a typical peridinioid tabulation of 4", 3a?, 7", 5""", 2"""" with the size, shape, and position of the plates represented by the conate areas.
Cingulum defined by transverse parallel ridges about 1 µm high, 5-7 µm apart, and fringed with coni, denticles, or spinules. On some specimens the cingulum is subdivided by longitudinal ridges and its floor is smooth or bears scattered coni.
Sulcal margins generally indefinite, and on most specimens, a hook-shaped scar occurs in the sulcus near its junction with the cingulum and generally a little right of centre.
Endoblast is comparatively large, broadly elliptical to ovoid in dorsoventral view, generally wider than long although on some specimens the reverse is true, and located about centrally with respect to the periphragm. Endoblast configuration approximates that of the periblast laterally but deviates apically and antapically. Endophragm is smooth and ca. 0.5 µm thick.
Archeopyle intercalary, large, irregularly hexagonal in outline, and with a narrower apical than antapical margin. Opening in endophragm corresponds with that in the periphragm. Operculum free.
Dimensions:
Length of periphragm is 106-140 µm, width of periphragm is 68-75 µm and the specimens have a length width ratio between 1:0.53 and 1:0.73 (mean 1:0.64). Length of endophragm is 53-70 µm, width 58-76 µm. Apical horn is 22-34 µm long; antapical horns 20-36 µm long.
Measurements based on 12 complete specimens.