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Filisphaera pachyderma
Filisphaera pachyderma Schiøler, 2005, p.29, pl.6, figs.16–21.
Holotype: Schiøler, 2005, pl.6, figs.17–20.
Age: Chattian–early Aquitanian.
Original description (Schiøler, P., 2005)
Filisphaera pachyderma sp. nov. (Pl. 6, figs 16–21)
Type species. Filisphaera filifera Bujak, 1984 emend. Head, 1994
Derivation of name. Greek: παχύ,thick; δερμα, skin. With reference to its thick cyst wall.
Diagnosis. Gonyaulacoid autocyst with an extremely thick autophragm consisting of a thin pedium and a very thick luxuria composed of a dense mat of slightly anastomosing fibrils that radiate outwards from the pedium. The archaeopyle is precingular, type P3´´. The cyst lacks any indication of paratabulation other than the archaeopyle.
Holotype. MGUH 26751, SM 320 (Pl. 6, figs 17–20).
Paratypes: (1) MGUH 26752, SM 319 (Pl. 6, fig. 16); (2) MGUH 26753, SM 302 (Pl. 6, fig. 21).
Horizon. Lark Formation, 5480–5510# (1670.3–1679.4 m). Lower Aquitanian.
Description. Small to intermediate-sized autocyst, sub-circular to oval in outline. The cyst wall is extremely thick and composed of two wall layers; a thin, smooth pedium (less than 0.5 µm thick) and a very thick luxuria (thickness: 8–12 µm). The luxuria is composed of closely spaced fibrils radiating out from the pedium to form a dense mat on the cyst. Each fibril seems to be slightly flexuous to anastomosing from its base to its tip (Pl. 6, fig. 20). The luxuria is finely granulate to pitted in surface view (Pl. 6, fig. 19). The archaeopyle is precingular, type P3´´, judged from its shape. Apart from the archaeopyle, the cyst lacks indications of paratabulation. In a population, cyst size and wall thickness varies only very little, whereas the overall shape may vary from being circular to oval. When oval, the long axis may be either polar or equatorial, resulting in specimens being either higher than broad (Pl. 6, fig. 21), or broader than high (Pl. 6, fig. 16). The former shape is the most common by far.
Dimensions. Fifteen specimens were measured.
Length: Holotype: 47 µm; Range: 45 (52) 57 µm
Width: Holotype: 52 µm; Range: 38 (46) 57 µm
Wall thickness: Holotype: 8 µm; Range: 8 (10) 12 µm
Stratigraphical range. Chattian to lower Aquitanian in the Alma-1X well.
Remarks. Filisphaera pachyderma differs from F. filifera Bujak, 1984 emend. Head, 1994 and from most other small to intermediate-sized dinoflagellate cysts with fibrous cyst wall ornament and a type P archaeopyle in its much thicker luxuria. Some specimens of Tectatodinium pellitum Wall, 1967 emend. Head, 1994 may possess a thick cyst wall, having a superficial resemblance with the new species, but they differ in having an interconnecting, irregular, ‘spongy’ and lanate luxuria instead of the radiating, fibrous luxuria of F. pachyderma (see Head, 1994, for discussion of luxuria morphology in the genera Tectatodinium and Filisphaera).
Holotype: Schiøler, 2005, pl.6, figs.17–20.
Age: Chattian–early Aquitanian.
Original description (Schiøler, P., 2005)
Filisphaera pachyderma sp. nov. (Pl. 6, figs 16–21)
Type species. Filisphaera filifera Bujak, 1984 emend. Head, 1994
Derivation of name. Greek: παχύ,thick; δερμα, skin. With reference to its thick cyst wall.
Diagnosis. Gonyaulacoid autocyst with an extremely thick autophragm consisting of a thin pedium and a very thick luxuria composed of a dense mat of slightly anastomosing fibrils that radiate outwards from the pedium. The archaeopyle is precingular, type P3´´. The cyst lacks any indication of paratabulation other than the archaeopyle.
Holotype. MGUH 26751, SM 320 (Pl. 6, figs 17–20).
Paratypes: (1) MGUH 26752, SM 319 (Pl. 6, fig. 16); (2) MGUH 26753, SM 302 (Pl. 6, fig. 21).
Horizon. Lark Formation, 5480–5510# (1670.3–1679.4 m). Lower Aquitanian.
Description. Small to intermediate-sized autocyst, sub-circular to oval in outline. The cyst wall is extremely thick and composed of two wall layers; a thin, smooth pedium (less than 0.5 µm thick) and a very thick luxuria (thickness: 8–12 µm). The luxuria is composed of closely spaced fibrils radiating out from the pedium to form a dense mat on the cyst. Each fibril seems to be slightly flexuous to anastomosing from its base to its tip (Pl. 6, fig. 20). The luxuria is finely granulate to pitted in surface view (Pl. 6, fig. 19). The archaeopyle is precingular, type P3´´, judged from its shape. Apart from the archaeopyle, the cyst lacks indications of paratabulation. In a population, cyst size and wall thickness varies only very little, whereas the overall shape may vary from being circular to oval. When oval, the long axis may be either polar or equatorial, resulting in specimens being either higher than broad (Pl. 6, fig. 21), or broader than high (Pl. 6, fig. 16). The former shape is the most common by far.
Dimensions. Fifteen specimens were measured.
Length: Holotype: 47 µm; Range: 45 (52) 57 µm
Width: Holotype: 52 µm; Range: 38 (46) 57 µm
Wall thickness: Holotype: 8 µm; Range: 8 (10) 12 µm
Stratigraphical range. Chattian to lower Aquitanian in the Alma-1X well.
Remarks. Filisphaera pachyderma differs from F. filifera Bujak, 1984 emend. Head, 1994 and from most other small to intermediate-sized dinoflagellate cysts with fibrous cyst wall ornament and a type P archaeopyle in its much thicker luxuria. Some specimens of Tectatodinium pellitum Wall, 1967 emend. Head, 1994 may possess a thick cyst wall, having a superficial resemblance with the new species, but they differ in having an interconnecting, irregular, ‘spongy’ and lanate luxuria instead of the radiating, fibrous luxuria of F. pachyderma (see Head, 1994, for discussion of luxuria morphology in the genera Tectatodinium and Filisphaera).