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Wilsonisphaera petila
From Fensome et al., 2019:
Wilsonisphaera petila (Corradini, 1973, p.186, pl.31, figs.1–2) Slimani, 1994, p.68–69.
Emendation: Slimani, 1994, p.68, as Wilsonisphaera petila.
Holotype: Corradini, 1973, pl.31, fig.2.
Originally Thalassiphora?, subsequently Disphaeria, thirdly (and now) Wilsonisphaera.
Taxonomic junior synonym: Glaphyrosphaera glabra, according to Schiøler and Wilson (1995, p.511).
Age: Senonian.
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Original description (Slimani, 1994) (translated by PKB 2024)
Proximate cyst, cavate. The pericyst is spheroidal to subspheroidal, broad and open dorsally. The endocyst located in the center of the pericyst is ovoidal to ellipsoidal and has a small apical protrusion 2 to 4 pm long. The endophragm and periphragm are smooth or chaffed to slightly granulated; they are separated by a broad pericoel and connected dorso-ventrally by a broad, hollow, funnel-shaped membranous process open on the periphragm side, and 18 to 26 µm in length. The periphragm is often folded with a more or less angular outline and supported by parasutural ridges. These ridges are low (1 -2 µm in height), solid, simple or/and slightly wavy to discontinuous with or without small tubercles and spines which are often more pronounced at the junction points. The paratabulation conforms to the formula: 4', 6", 6c, 5"', 1"". The paracingulum is wide (up to 10 µm) and segmented by very fine ridges; it is strongly laevorotatory with a distance between its two ends of up to 25 µm. The parasulcus is indicated by an unsegmented subrectangular longitudinal surface that extends from the apex, widening slightly toward the antapex. The archaeopyle is precingulate of type P(3"); it consists of a small endoarchaeopyle (around 30 pm in length) with an operculum of pentagonal outline, and a large periarchaeopyle (around 60 µm in length) of subrectangular outline. endo-operculum is apparently attached and constantly bears two membranous processes (up to 10 µm wide and 22 pm long), thin, rigid and often divided distally in small unequal branches The periopercle is monotabular and free.
Dimensions: Holotype (Corradini, 1973, pl. 31, fig. 2): pericyst: 85 x 103 µm, endocyst: 40 x 50 µm. 80 - 110 µm, width: 60 - 100 µm; length: 40 - 64 µm, width: 30 - 50 µm Number of specimens measured: 15. Material: 60 copies.
Discussion: This species resembles Stephodinium sp. in Wilson (1971: pl. 2, fig. 17) which the same author attributed to his Glaphyrosphaera glabra in his unpublished Ph. D. work (1974); and that Corradini (1973) mentioned as close to his Thalassiphora? petilla. According to the original description of Th? petila it is mentioned that the identification of the archaeopyle on the endocyst is uncertain because of the folds which deform the whole cyst, but the dorsal opening of the periphragm is present and suggests a precingular archaeopyle. This first recalls the genus Invertocysta. Because Thalassiphora has a large ventral opening in its pericoel; the dorsal archaeopyle being of type P(3"), (see comparison of Wilsonisphaera above). By analyzing the Phototype photo of Th? petila (pl. 31, fig. 2), we realized that it is not congeneric with Invertocysta, but its characters correspond to those of Wilsonisphaera g., its endocyst being located in the center of the cyst, the processes of the endooperculum being clearly visible through the periarchaeopyle which is located on the right side of the specimen; the membranous process which connects the periphragm and the endophragm is only slightly marked on the left side of the holotype and paratype (pl. 31, fig. 1). (Corradini, 1973) comb.
Stratigraphic distribution:
Halembaye: ex. 1, Lower Campanian. (G. quadrata zone). Turnhout: -987 to -807.90 m, lower Campanian. - Lower part. from the upper Maastrichtian.Wilson (1971), Campanian - lower Maastrichtian limit, Hvidskud Klint, Denmark. Corradini (1973), Senonian, Northern Apennines, Italy. In Wilson (1974), Maastrichtian inf. (occidentalis/lanceolata zone) Hvidskud Klint, Denmark. Schioler and Wilson (1993), Maastrichtian, North Sea, Danish territorial area.
Wilsonisphaera petila (Corradini, 1973, p.186, pl.31, figs.1–2) Slimani, 1994, p.68–69.
Emendation: Slimani, 1994, p.68, as Wilsonisphaera petila.
Holotype: Corradini, 1973, pl.31, fig.2.
Originally Thalassiphora?, subsequently Disphaeria, thirdly (and now) Wilsonisphaera.
Taxonomic junior synonym: Glaphyrosphaera glabra, according to Schiøler and Wilson (1995, p.511).
Age: Senonian.
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Original description (Slimani, 1994) (translated by PKB 2024)
Proximate cyst, cavate. The pericyst is spheroidal to subspheroidal, broad and open dorsally. The endocyst located in the center of the pericyst is ovoidal to ellipsoidal and has a small apical protrusion 2 to 4 pm long. The endophragm and periphragm are smooth or chaffed to slightly granulated; they are separated by a broad pericoel and connected dorso-ventrally by a broad, hollow, funnel-shaped membranous process open on the periphragm side, and 18 to 26 µm in length. The periphragm is often folded with a more or less angular outline and supported by parasutural ridges. These ridges are low (1 -2 µm in height), solid, simple or/and slightly wavy to discontinuous with or without small tubercles and spines which are often more pronounced at the junction points. The paratabulation conforms to the formula: 4', 6", 6c, 5"', 1"". The paracingulum is wide (up to 10 µm) and segmented by very fine ridges; it is strongly laevorotatory with a distance between its two ends of up to 25 µm. The parasulcus is indicated by an unsegmented subrectangular longitudinal surface that extends from the apex, widening slightly toward the antapex. The archaeopyle is precingulate of type P(3"); it consists of a small endoarchaeopyle (around 30 pm in length) with an operculum of pentagonal outline, and a large periarchaeopyle (around 60 µm in length) of subrectangular outline. endo-operculum is apparently attached and constantly bears two membranous processes (up to 10 µm wide and 22 pm long), thin, rigid and often divided distally in small unequal branches The periopercle is monotabular and free.
Dimensions: Holotype (Corradini, 1973, pl. 31, fig. 2): pericyst: 85 x 103 µm, endocyst: 40 x 50 µm. 80 - 110 µm, width: 60 - 100 µm; length: 40 - 64 µm, width: 30 - 50 µm Number of specimens measured: 15. Material: 60 copies.
Discussion: This species resembles Stephodinium sp. in Wilson (1971: pl. 2, fig. 17) which the same author attributed to his Glaphyrosphaera glabra in his unpublished Ph. D. work (1974); and that Corradini (1973) mentioned as close to his Thalassiphora? petilla. According to the original description of Th? petila it is mentioned that the identification of the archaeopyle on the endocyst is uncertain because of the folds which deform the whole cyst, but the dorsal opening of the periphragm is present and suggests a precingular archaeopyle. This first recalls the genus Invertocysta. Because Thalassiphora has a large ventral opening in its pericoel; the dorsal archaeopyle being of type P(3"), (see comparison of Wilsonisphaera above). By analyzing the Phototype photo of Th? petila (pl. 31, fig. 2), we realized that it is not congeneric with Invertocysta, but its characters correspond to those of Wilsonisphaera g., its endocyst being located in the center of the cyst, the processes of the endooperculum being clearly visible through the periarchaeopyle which is located on the right side of the specimen; the membranous process which connects the periphragm and the endophragm is only slightly marked on the left side of the holotype and paratype (pl. 31, fig. 1). (Corradini, 1973) comb.
Stratigraphic distribution:
Halembaye: ex. 1, Lower Campanian. (G. quadrata zone). Turnhout: -987 to -807.90 m, lower Campanian. - Lower part. from the upper Maastrichtian.Wilson (1971), Campanian - lower Maastrichtian limit, Hvidskud Klint, Denmark. Corradini (1973), Senonian, Northern Apennines, Italy. In Wilson (1974), Maastrichtian inf. (occidentalis/lanceolata zone) Hvidskud Klint, Denmark. Schioler and Wilson (1993), Maastrichtian, North Sea, Danish territorial area.