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Thalassiphora graciliis
From Fensome et al., 2019:
Thalassiphora graciliis Heilmann-Clausen and Van Simaeys, 2005, p.182,184, pl.12, figs.1–3; pl.14, fig.3.
Holotype: Heilmann-Clausen and Van Simaeys, 2005, pl.12, fig.1.
Age: Middle–Late Eocene.
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Original description (Heilmann-Clausen and Van Simaeys, 2005):
Thalassiphora gracilis sp. nov. (Plate 12, figs. 1–3; Plate 14, fig. 3)
?Thalassiphora cf. velata (Deflandre & Cookson 1955) Eisenack & Gocht 1960; Manum, 1976, pl. 2, fig. 14.
?Thalassiphorasp. aff. T. cf. velata (Deflandre & Cookson) in Manum 1976; De Coninck, 1986, p. 20, pl. 10, fig. 12.
Description. Dinoflagellate cysts of the genus Thalassiphora; cavate, with the pericyst completely enclosing the endocyst. The phragma are separated everywhere except middorsally and midventrally, where the periphragm is appressed to the endophragm. The pericyst outline in dorsoventral view is lobate to angular due to folds in the periphragm. The pericyst is dorsoventrally flattened. The endocyst is subspherical. The periphragm is somewhat crumpled, thin and translucent with scattered fine granules and may vary from almost smooth to finely fibrous. On the middorsal surface of the periphragm, a few weakly developed radiating striae are usually formed by alignment of the surface ornament. The endophragm is distinctly thicker and darker colored than the periphragm. It is finely punctate, apparently due to a finely spongy structure. On the middorsal and midventral surfaces, where the phragma are appressed, a number of simple, conical or hairlike spines are usually developed; these are up to 10 µm long. The archeopyle is precingular, Type P (3" only). Apart from the archeopyle, the paratabulation is only vaguely indicated by the folds in the periphragm.
Derivation of name. From Latin gracilis meaning thin or fine, with reference to the thin, translucent periphragm.
Designation of the holotype. Plate 12, fig. 1, Slide 2638 K5, England Finder coordinates L43/1. MGUH 27793. Kysing-4 borehole, sample 2638, Middle Eocene. Specimen dimensions: Pericyst length 143 µm; pericyst breadth 131 µm; endocyst length 62 µm; endocyst breadth 48 µm.
Designation of the paratype. Paratype 1: Plate 12, fig. 3, Slide 2665 G1, England Finder coordinates S25/4. MGUH 27794. Kysing-4 borehole, sample 2665, Upper Eocene. Paratype 2: Plate 12, fig. 2, Slide 2650 J4, England Finder coordinates M39/2. MGUH 27795. Kysing-4 borehole, sample 2650, Middle Eocene. Paratype 3: Plate 14, fig. 3, Slide 2659 H2, England Finder coordinates Q32/2. MGUH 27796. Kysing-4 borehole, sample 2659, Middle Eocene.
Dimensions of measured specimens. Pericyst length 88 (109) 143 µm. Pericyst breadth 94 (115) 131 µm. Endocyst length 47 (56) 66 µm. Endocyst breadth 48 (56) 66 µm. Thickness of endophragm 0.5 (1.5) 2 µm. (9 specimens measured).
Comparison. Thalassiphora gracilis sp. nov. closely resembles Thalassiphora pelagica (Eisenack 1954) Eisenack & Gocht 1960, from which it differs by the more irregular outline of the pericyst, the thinner, translucent and crumpled periphragm, and the presence of spines and of radiating striae. The two species occur together in the samples studied herein, where they form two morphologically discrete populations. A form with a coarsely granular central body described in De Coninck (1986) as “Thalassiphorasp. aff. T. cf. velata (Deflandre & Cookson) in Manum 1976” is provisionally included in the species. Similar specimens with granular endocysts are recorded in samples 2634 and 2651.
Thalassiphora graciliis Heilmann-Clausen and Van Simaeys, 2005, p.182,184, pl.12, figs.1–3; pl.14, fig.3.
Holotype: Heilmann-Clausen and Van Simaeys, 2005, pl.12, fig.1.
Age: Middle–Late Eocene.
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Original description (Heilmann-Clausen and Van Simaeys, 2005):
Thalassiphora gracilis sp. nov. (Plate 12, figs. 1–3; Plate 14, fig. 3)
?Thalassiphora cf. velata (Deflandre & Cookson 1955) Eisenack & Gocht 1960; Manum, 1976, pl. 2, fig. 14.
?Thalassiphorasp. aff. T. cf. velata (Deflandre & Cookson) in Manum 1976; De Coninck, 1986, p. 20, pl. 10, fig. 12.
Description. Dinoflagellate cysts of the genus Thalassiphora; cavate, with the pericyst completely enclosing the endocyst. The phragma are separated everywhere except middorsally and midventrally, where the periphragm is appressed to the endophragm. The pericyst outline in dorsoventral view is lobate to angular due to folds in the periphragm. The pericyst is dorsoventrally flattened. The endocyst is subspherical. The periphragm is somewhat crumpled, thin and translucent with scattered fine granules and may vary from almost smooth to finely fibrous. On the middorsal surface of the periphragm, a few weakly developed radiating striae are usually formed by alignment of the surface ornament. The endophragm is distinctly thicker and darker colored than the periphragm. It is finely punctate, apparently due to a finely spongy structure. On the middorsal and midventral surfaces, where the phragma are appressed, a number of simple, conical or hairlike spines are usually developed; these are up to 10 µm long. The archeopyle is precingular, Type P (3" only). Apart from the archeopyle, the paratabulation is only vaguely indicated by the folds in the periphragm.
Derivation of name. From Latin gracilis meaning thin or fine, with reference to the thin, translucent periphragm.
Designation of the holotype. Plate 12, fig. 1, Slide 2638 K5, England Finder coordinates L43/1. MGUH 27793. Kysing-4 borehole, sample 2638, Middle Eocene. Specimen dimensions: Pericyst length 143 µm; pericyst breadth 131 µm; endocyst length 62 µm; endocyst breadth 48 µm.
Designation of the paratype. Paratype 1: Plate 12, fig. 3, Slide 2665 G1, England Finder coordinates S25/4. MGUH 27794. Kysing-4 borehole, sample 2665, Upper Eocene. Paratype 2: Plate 12, fig. 2, Slide 2650 J4, England Finder coordinates M39/2. MGUH 27795. Kysing-4 borehole, sample 2650, Middle Eocene. Paratype 3: Plate 14, fig. 3, Slide 2659 H2, England Finder coordinates Q32/2. MGUH 27796. Kysing-4 borehole, sample 2659, Middle Eocene.
Dimensions of measured specimens. Pericyst length 88 (109) 143 µm. Pericyst breadth 94 (115) 131 µm. Endocyst length 47 (56) 66 µm. Endocyst breadth 48 (56) 66 µm. Thickness of endophragm 0.5 (1.5) 2 µm. (9 specimens measured).
Comparison. Thalassiphora gracilis sp. nov. closely resembles Thalassiphora pelagica (Eisenack 1954) Eisenack & Gocht 1960, from which it differs by the more irregular outline of the pericyst, the thinner, translucent and crumpled periphragm, and the presence of spines and of radiating striae. The two species occur together in the samples studied herein, where they form two morphologically discrete populations. A form with a coarsely granular central body described in De Coninck (1986) as “Thalassiphorasp. aff. T. cf. velata (Deflandre & Cookson) in Manum 1976” is provisionally included in the species. Similar specimens with granular endocysts are recorded in samples 2634 and 2651.