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Thalassiphora delicata
Thalassiphora delicata Williams and Downie, 1966c, p.235, pl.26, fig.8. Emendation: Eaton, 1976, p.287, as Thalassiphora delicata.
Originally (and now) Thalassiphora, subsequently Disphaeria.
Norvick, 1973 transferred this species to Disphaeria Cookson and Eisenack, 1960; however, Lentin and Williams, 1977 retained it in Thalassiphora.
Holotype: Williams and Downie, 1966, pl. 26, fig. 8; Bujak et al., 1980, pl.10, fig.8
Locus typicus: London Clay, Enborne, southern England
Stratum typicum: Early-middle Eocene
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Thalassiphora delicata Williams and Downie, 1966c, emend. Eaton, 1976. Emended by Eaton (1976, p.287), central body subspherical or ellipsoidal, formed by the thin smooth endophragm. Periphragm dorsoventrally flattened with a subcircular or elliptical outline, smooth or with a minutely fenestrate appearance. Periphragm separated from the endophragm by a distinct pericoel, except over the mid-dorsal area where the two layers are in contact. Low simple linear thickenings of the periphragm are variably developed and these define the plate boundaries. Reflected tabulation 4', 1a, 5", 4c, 5"’, 1p, 1"”; archeopyle precingular, formed by the displacement of plate 3". Distribution of the plates strongly asymmetrical. Most of the ventral surface is occupied by plates 1" and 2"’. Sulcal zone offset well to the left of the mid-ventral line, occupying the lateral margin of the periphragm. A large opening is usually developed on the ventral surface of the periphragm, formed by the displacement of plate 1". Size (from Eaton), periphragm 75 x 62 to 112 x 120 µm, endophragm 36 x 30 to 60 x 46 µm.
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Original diagnosis: Williams and Downie, 1966, p. 235
A Thalassiphora with ellipsoidal central body possessing a smooth thin wall. Periphragm in form of wing lamella, delicate, often irregularly folded and turned over on its margin. No keel present. Periphragm can be perforate. An archeopyle may be present. Dimensions: Observed range: periphragm 75 x 62 µm to 112 x 120 µm; endphragm 36 x 30 µm to 60 x 46 µm. (n = 12).
Original dsescription: Williams and Downie, 1966, p. 235
T. delicata exhibits considerable variation in width of the periphragm, this is partly due to unequal folding. Some of the folds on the periphragm suggest the presence of a cingulum; this is however difficult to visualise since the periphragm does not completely surround the central body. Both the endophragm and periphragm are thin.
Emended diagnosis: Eaton, 1976, p. 287
Central body subspherical or ellipsoidal, formed by the thin smooth endophragm. Periphragm dorsoventrally flattened with a subcircular or elliptical outline, smooth or with a minutely fenestrate appearance. Periphragm separated from the endophragm by a distinct pericoel, except over the mid-dorsal area where the two layers are in contact. Low simple linear thickenings of the periphragm are variably developed, and these define the plate boundaries. Reflected tabulation 4', 1a, 5'', 4c, 5''', 1p, 1''''; archaepyle precingular, formed by the displacement of plate 3''.
Distribution of the plates strongly asymmetrical. Most of the ventral surface is occupied by plates 1'' and 2'''. Sulcal zone offset well to the left of the mid-ventral line, occupying the lateral margin of the periphragm. A large opening is usually developed on the ventral surface of the periphragm, formed by displacement of plate 1''.
Affinities:
Eaton, 1976, p. 287: T. delicata shows a variable development of linear thickenings of the periphragm defining the reflected tabulation. In some specimens only the cingular zone and a few of the other plate boundaries are recognizable; in others all the plates are clearly defined apart from those on the mid-dorsal area where the periphragm and indophragm are in contact (Figs 18B, 20B). There is some uncertainty in the reflected tabulation of the area where the sulcal zone crosses the cingular zone. The periphragm in this area frequently exhibits folds which tend to obscure the plate boundaries. Two small plate areas have been recognized which may include the anterior sulcal plate. A large posterior intercalary plate (1p) is developed to the left of the sulcal zone, bordered by plates 4''', 5''', and 1''''. The development of a full reflected tabluation on the ventral surface allows the recognition of its unusual asymmetry, and the identification of the area of the large opening.
Originally (and now) Thalassiphora, subsequently Disphaeria.
Norvick, 1973 transferred this species to Disphaeria Cookson and Eisenack, 1960; however, Lentin and Williams, 1977 retained it in Thalassiphora.
Holotype: Williams and Downie, 1966, pl. 26, fig. 8; Bujak et al., 1980, pl.10, fig.8
Locus typicus: London Clay, Enborne, southern England
Stratum typicum: Early-middle Eocene
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Thalassiphora delicata Williams and Downie, 1966c, emend. Eaton, 1976. Emended by Eaton (1976, p.287), central body subspherical or ellipsoidal, formed by the thin smooth endophragm. Periphragm dorsoventrally flattened with a subcircular or elliptical outline, smooth or with a minutely fenestrate appearance. Periphragm separated from the endophragm by a distinct pericoel, except over the mid-dorsal area where the two layers are in contact. Low simple linear thickenings of the periphragm are variably developed and these define the plate boundaries. Reflected tabulation 4', 1a, 5", 4c, 5"’, 1p, 1"”; archeopyle precingular, formed by the displacement of plate 3". Distribution of the plates strongly asymmetrical. Most of the ventral surface is occupied by plates 1" and 2"’. Sulcal zone offset well to the left of the mid-ventral line, occupying the lateral margin of the periphragm. A large opening is usually developed on the ventral surface of the periphragm, formed by the displacement of plate 1". Size (from Eaton), periphragm 75 x 62 to 112 x 120 µm, endophragm 36 x 30 to 60 x 46 µm.
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Original diagnosis: Williams and Downie, 1966, p. 235
A Thalassiphora with ellipsoidal central body possessing a smooth thin wall. Periphragm in form of wing lamella, delicate, often irregularly folded and turned over on its margin. No keel present. Periphragm can be perforate. An archeopyle may be present. Dimensions: Observed range: periphragm 75 x 62 µm to 112 x 120 µm; endphragm 36 x 30 µm to 60 x 46 µm. (n = 12).
Original dsescription: Williams and Downie, 1966, p. 235
T. delicata exhibits considerable variation in width of the periphragm, this is partly due to unequal folding. Some of the folds on the periphragm suggest the presence of a cingulum; this is however difficult to visualise since the periphragm does not completely surround the central body. Both the endophragm and periphragm are thin.
Emended diagnosis: Eaton, 1976, p. 287
Central body subspherical or ellipsoidal, formed by the thin smooth endophragm. Periphragm dorsoventrally flattened with a subcircular or elliptical outline, smooth or with a minutely fenestrate appearance. Periphragm separated from the endophragm by a distinct pericoel, except over the mid-dorsal area where the two layers are in contact. Low simple linear thickenings of the periphragm are variably developed, and these define the plate boundaries. Reflected tabulation 4', 1a, 5'', 4c, 5''', 1p, 1''''; archaepyle precingular, formed by the displacement of plate 3''.
Distribution of the plates strongly asymmetrical. Most of the ventral surface is occupied by plates 1'' and 2'''. Sulcal zone offset well to the left of the mid-ventral line, occupying the lateral margin of the periphragm. A large opening is usually developed on the ventral surface of the periphragm, formed by displacement of plate 1''.
Affinities:
Eaton, 1976, p. 287: T. delicata shows a variable development of linear thickenings of the periphragm defining the reflected tabulation. In some specimens only the cingular zone and a few of the other plate boundaries are recognizable; in others all the plates are clearly defined apart from those on the mid-dorsal area where the periphragm and indophragm are in contact (Figs 18B, 20B). There is some uncertainty in the reflected tabulation of the area where the sulcal zone crosses the cingular zone. The periphragm in this area frequently exhibits folds which tend to obscure the plate boundaries. Two small plate areas have been recognized which may include the anterior sulcal plate. A large posterior intercalary plate (1p) is developed to the left of the sulcal zone, bordered by plates 4''', 5''', and 1''''. The development of a full reflected tabluation on the ventral surface allows the recognition of its unusual asymmetry, and the identification of the area of the large opening.