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Hystrichodinium solare
From Fensome et al., 2019:
Hystrichodinium solare Pestchevitskaya, 2009, p.111–112, pl.1, figs.6,10; text-fig.2D. Holotype: Pestchevitskaya, 2009, pl,1, fig.10. Age: Hauterivian.
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Original description (Pestchevitskaya, 2009) (translated from Russian):
Hystrichodinium solare Pestchevitskaya sp. n.
Plate, figs. 6, 10; fig. 2, G
1993 Hystrichodinium voigtii: Nøhr-Hansen, pl. 10, fi g. 4
1998 Hystrichodinium sp. A: Lebedeva, Nikitenko, Plate II, fig. 6.
Origin of the name. From Latin solare (sunny), after the shape of the cyst.
Holotype. Specimen No. 842/1403.1-40 CSGM, pl. I, fig. 10; borehole Gorshkovskaya 1017, depth 2629.7 m, sample 38, prep. 1403.1, lower Hauterivian.
Diagnosis. Cyst skolochorate, bi-layered; layers appressed together except of parasutures; endophragm rather thick, granular, forms rounded or sub-rhombic endocyst; pericyst is of the same shape with somewhat thiner, transparent periphragm, sculptured with fi ne granules; periphragm forms lower parasutural septa giving rise to 13–16 long simple processes; paratabulation rather distinct, expressed by parasutural features and septa; paracingulum laevorotatory; formula: 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’; archeopyle precingular, type 1Р (3’’).
Material. 8 specimens in good and satisfactory preservation.
Description. The cyst is scolochrate, two-layered, the layers are pressed except for the sutures between the paraplates. The endophragm is quite dense, granulated, forming an endocyst of a rounded or rhombic-rounded shape. The general outline of the pericysta is the same. The periphragm is thinner, transparent, and finely granulated. It forms low parasutural septa (2–5 μm), which give rise to 13–16 long (from 1/2 to the entire width of the endocyst, sometimes more) simple, distally closed outgrowths, which are located around the circumference of the cyst: in the lateral, apical, and antapical areas. They are absent on the dorsal and ventral sides (along the cingulum and sulcus). The outgrowths are columnar in shape, with widened bases, and rounded ends. The distal ends of the outgrowths are often sculpted with larger granules than on the rest of the pericyst surface. When well preserved, the outgrowths are straight, which is why the cyst has the shape of a sun; when poorly preserved, they are crumpled or bent. Paratabulation is quite clearly expressed, expressed by parasutural lines and septa, formula 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’. Left-handed paracingulum and parasulcus are marked by septa, sometimes by small folds of periphragm. Archaeopile precingular, type 1P (3’’).
Dimensions (µm). Total diameter of cyst (with outgrowths) – 90–125; length of pericyst (without outgrowths) – 48–56; width of pericyst – 50–66; length of endocyst – 45–55; width of endocyst – 45–58; length of outgrowths – 20–37; width of outgrowths – 5–6.
Variability. The number and length of outgrowths vary, as well as, slightly, the shape of endo- and pericyst: from rounded to rounded-rhombic.
The distal ends of the outgrowths can be sculpted with large granules or bear the same ornamentation as the rest of the pericyst surface.
Comparison. In morphology, the new species occupies an intermediate place between H. pulchrum [Deflandre, 1935; Alberti, 1961; Davey et al., 1966; Marheinecke, 1992] and H. voigtii [Alberti, 1961]. The latter is similar in the number and shape of outgrowths, but has high septa, which give the cyst a characteristic polygonal shape. The species H. pulchrum has lower septa, as well as thinner and more numerous outgrowths.
Location. Nordvik Peninsula, outcrop 36, layer 11, lower Hauterivian, Gorshkovskaya 1017 borehole, int. 2656–2628 m, lower Hauterivian.
Hystrichodinium solare Pestchevitskaya, 2009, p.111–112, pl.1, figs.6,10; text-fig.2D. Holotype: Pestchevitskaya, 2009, pl,1, fig.10. Age: Hauterivian.
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Original description (Pestchevitskaya, 2009) (translated from Russian):
Hystrichodinium solare Pestchevitskaya sp. n.
Plate, figs. 6, 10; fig. 2, G
1993 Hystrichodinium voigtii: Nøhr-Hansen, pl. 10, fi g. 4
1998 Hystrichodinium sp. A: Lebedeva, Nikitenko, Plate II, fig. 6.
Origin of the name. From Latin solare (sunny), after the shape of the cyst.
Holotype. Specimen No. 842/1403.1-40 CSGM, pl. I, fig. 10; borehole Gorshkovskaya 1017, depth 2629.7 m, sample 38, prep. 1403.1, lower Hauterivian.
Diagnosis. Cyst skolochorate, bi-layered; layers appressed together except of parasutures; endophragm rather thick, granular, forms rounded or sub-rhombic endocyst; pericyst is of the same shape with somewhat thiner, transparent periphragm, sculptured with fi ne granules; periphragm forms lower parasutural septa giving rise to 13–16 long simple processes; paratabulation rather distinct, expressed by parasutural features and septa; paracingulum laevorotatory; formula: 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’; archeopyle precingular, type 1Р (3’’).
Material. 8 specimens in good and satisfactory preservation.
Description. The cyst is scolochrate, two-layered, the layers are pressed except for the sutures between the paraplates. The endophragm is quite dense, granulated, forming an endocyst of a rounded or rhombic-rounded shape. The general outline of the pericysta is the same. The periphragm is thinner, transparent, and finely granulated. It forms low parasutural septa (2–5 μm), which give rise to 13–16 long (from 1/2 to the entire width of the endocyst, sometimes more) simple, distally closed outgrowths, which are located around the circumference of the cyst: in the lateral, apical, and antapical areas. They are absent on the dorsal and ventral sides (along the cingulum and sulcus). The outgrowths are columnar in shape, with widened bases, and rounded ends. The distal ends of the outgrowths are often sculpted with larger granules than on the rest of the pericyst surface. When well preserved, the outgrowths are straight, which is why the cyst has the shape of a sun; when poorly preserved, they are crumpled or bent. Paratabulation is quite clearly expressed, expressed by parasutural lines and septa, formula 4’, 6’’, 6c, 5s, 6’’’, 1p, 1’’’’. Left-handed paracingulum and parasulcus are marked by septa, sometimes by small folds of periphragm. Archaeopile precingular, type 1P (3’’).
Dimensions (µm). Total diameter of cyst (with outgrowths) – 90–125; length of pericyst (without outgrowths) – 48–56; width of pericyst – 50–66; length of endocyst – 45–55; width of endocyst – 45–58; length of outgrowths – 20–37; width of outgrowths – 5–6.
Variability. The number and length of outgrowths vary, as well as, slightly, the shape of endo- and pericyst: from rounded to rounded-rhombic.
The distal ends of the outgrowths can be sculpted with large granules or bear the same ornamentation as the rest of the pericyst surface.
Comparison. In morphology, the new species occupies an intermediate place between H. pulchrum [Deflandre, 1935; Alberti, 1961; Davey et al., 1966; Marheinecke, 1992] and H. voigtii [Alberti, 1961]. The latter is similar in the number and shape of outgrowths, but has high septa, which give the cyst a characteristic polygonal shape. The species H. pulchrum has lower septa, as well as thinner and more numerous outgrowths.
Location. Nordvik Peninsula, outcrop 36, layer 11, lower Hauterivian, Gorshkovskaya 1017 borehole, int. 2656–2628 m, lower Hauterivian.