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Impagidinium wardii
From Iakovleva and Heilmann-Clausen, 2021
Impagidinium wardii sp. nov. Plate 9, figures 5–6
Synonymy. Impagidinium sp. A in Iakovleva and Heilmann- Clausen, 2010, pl. 7, figs 14, 17.
Holotype. Slide 2802-G2. England Finder coordinates N36/4; MGUH 32071.
Paratype. Slide 2802-G2. England Finder coordinates N25; MGUH 32072.
Type stratum and locality. Sample 18.95 m, Kulsary Formation, Aktulagay outcrop section, Kazakhstan.
Diagnosis. A small gonyaulacoid proximochorate, finely granulated cyst with low and smooth septa and a precingular archeopyle.
Description. A small, relatively thick-walled species of Impagidinium. The central body is egg-shaped to subspherical. The epicyst is slightly longer than the hypocyst. The paracinculum is rather broad (ca. 5 µm). Septa are low and smooth (hyaline). The distal margin of the septa varies (within an individual cyst) from ragged in most parts, to locally entire, and locally finely denticulate. A prominent feature of the cyst is a fine and dense granulation of the central body caused by closely spaced minute but rather high (up to ca. 0.5 µm high) granules. A gonyaulacacean paratabulation is indicated by parasutural septa, with the possible formula 3’, 5–6”, 5c, 5’’’, 1p, 1’’’’. The archeopyle is precingular and formed by the removal of paraplate 3”.
Dimensions. Holotype: total cyst length 32 µm; total cyst width 30 µm; central body length 29 µm; central body width 26 µm; height of septa 2 µm (average); autophragm thickness 1 µm. Paratype: total cyst length 38 µm; total cyst width 36 µm; central body length 34 µm; central body width 31 µm; height of septa 2.5–3.5 µm; autophragm thickness 0.8 µm. Dimensions of measured specimens: total cyst length 32–40 µm (mean 37 µm); total cyst width 30–40 µm (mean 35 µm); central body length 29–35 µm (mean 32 µm); central body width 26–35 µm (mean 31 µm); height of septa 1.8–3.6 µm (mean 2.5 µm); autophragm thickness 0.7–1 µm (mean 0.9 µm); 9 specimens measured.
Comparison. Impagidinium wardii sp. nov. differs from other species of Impagidinium mainly by its fine and dense granulation, as well as by the small size and subspherical habitus of the cyst.
Stratigraphic range. Ypresian.
Derivation of name. In honor of the British paleontologist and field geologist David J. Ward, who, together with Chris King, studied the Aktulagay section and provided the samples for the present study.
Impagidinium wardii sp. nov. Plate 9, figures 5–6
Synonymy. Impagidinium sp. A in Iakovleva and Heilmann- Clausen, 2010, pl. 7, figs 14, 17.
Holotype. Slide 2802-G2. England Finder coordinates N36/4; MGUH 32071.
Paratype. Slide 2802-G2. England Finder coordinates N25; MGUH 32072.
Type stratum and locality. Sample 18.95 m, Kulsary Formation, Aktulagay outcrop section, Kazakhstan.
Diagnosis. A small gonyaulacoid proximochorate, finely granulated cyst with low and smooth septa and a precingular archeopyle.
Description. A small, relatively thick-walled species of Impagidinium. The central body is egg-shaped to subspherical. The epicyst is slightly longer than the hypocyst. The paracinculum is rather broad (ca. 5 µm). Septa are low and smooth (hyaline). The distal margin of the septa varies (within an individual cyst) from ragged in most parts, to locally entire, and locally finely denticulate. A prominent feature of the cyst is a fine and dense granulation of the central body caused by closely spaced minute but rather high (up to ca. 0.5 µm high) granules. A gonyaulacacean paratabulation is indicated by parasutural septa, with the possible formula 3’, 5–6”, 5c, 5’’’, 1p, 1’’’’. The archeopyle is precingular and formed by the removal of paraplate 3”.
Dimensions. Holotype: total cyst length 32 µm; total cyst width 30 µm; central body length 29 µm; central body width 26 µm; height of septa 2 µm (average); autophragm thickness 1 µm. Paratype: total cyst length 38 µm; total cyst width 36 µm; central body length 34 µm; central body width 31 µm; height of septa 2.5–3.5 µm; autophragm thickness 0.8 µm. Dimensions of measured specimens: total cyst length 32–40 µm (mean 37 µm); total cyst width 30–40 µm (mean 35 µm); central body length 29–35 µm (mean 32 µm); central body width 26–35 µm (mean 31 µm); height of septa 1.8–3.6 µm (mean 2.5 µm); autophragm thickness 0.7–1 µm (mean 0.9 µm); 9 specimens measured.
Comparison. Impagidinium wardii sp. nov. differs from other species of Impagidinium mainly by its fine and dense granulation, as well as by the small size and subspherical habitus of the cyst.
Stratigraphic range. Ypresian.
Derivation of name. In honor of the British paleontologist and field geologist David J. Ward, who, together with Chris King, studied the Aktulagay section and provided the samples for the present study.