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Thalassiphora pelagica
From Fensome et al., 2019:
Thalassiphora pelagica (Eisenack, 1954b, p.71, pl.12, figs.17–18) Eisenack and Gocht, 1960, p.513–514.
Emendation: Benedek and Gocht, 1981, p.59–61, as Thalassiphora pelagica.
Holotype: Eisenack, 1954b, pl.12, fig.17. Originally Pterospermopsis (Appendix A), subsequently (and now) Thalassiphora, thirdly Disphaeria.
Lentin and Williams (1977b, p.54) retained this species in Thalassiphora. Taxonomic junior synonyms: Thalassiphora sueroi and Thalassiphora (as Disphaeria) balcanica, both according to Stover and Evitt (1978, p.194) — however, Sütő-Szentai (2000, p.162) retained Thalassiphora (as Spiniferites) balcanica; Pterocystidiopsis (as Thalassiphora) velata and Adnatosphaeridium (as Thalassiphora) patulum, both according to Benedek and Gocht (1981, p.59) — however, Lentin and Williams (1985, p.354) retained Thalassiphora patula and Brinkhuis and Biffi (1993, p.179) retained Pterocystidiopsis (as and now Thalassiphora) velata; Subathua sahnii, according to Lentin and Williams (1985, p.340) — however, Subathua sahnii is now considered to be a taxonomic junior synonym of Adnatosphaeridium (as and now Thalassiphora) patulum; Subathua spinosa, according to Lentin and Williams (1985, p.340) — however, Stover and Williams (1987, p.207) retained Subathua (as Thalassiphora) spinosa (now Thalassiphora simlaensis).
Locus typicus: Samlandt, E. Prussia, Russia
Stratum typicum: Early Oligocene
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Translation Eisenack, 1954: LPP
Translation Gocht, 1969: Geological Survey of Canada
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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 pelagica (Eisenack, 1954b) Eisenack and Gocht, 1960, emend. Benedek and Gocht, 1981. Emendation from Benedek and Gocht (1981, p.59-61), body polygonal, longer than wide, divided into fields through more or less steep border ridges. Cingulum slightly curved to the left, in the form of a simple crest. Longitudinal furrow unsegmented, occasionally with a flagellar pore. Lateral pre- and postcingular fields 1", 5", 2"’-5"’ large, polygonal. 2" and 4" slightly smaller, 6" narrow, rectangular, usually indistinctly demarcated from the sulcus. 3" developed as steep, spine-shaped projection, with horseshoe-shaped basis. 1" small, usually incorporated in the sulcal field. Dorsal (2',3') and ventral apical fields (1',4') separated by a crested fringe, but hardly demarcated from each other. Antapical field (1"”) large, polygonal, slightly inclined towards the longitudinal axis, often with central hump. Paratabulation 4', 6", 0c, 5"’, 1"”, s (border ridges 2'/3' and 4'/1', 6"/s and s/1"’/2"’ often not or only insufficiently marked). Archeopyle plate 3". Wall two-layered, of cellular-fibrous structure. Both wall layers merging without sharp demarcation. Inner and outer surface covered by a thin cover membrane (tectum). Wall cross-sections show a labyrinthic or reticular meshwork with thickened areas and pores. Inner tectum perforated. The inner wall layer interspersed with irregular but well demarcated cavities lying roughly in one plane. During the individual development the ventral outer layer of the wall is reduced to a thin lamina under the outer tectum (resorbed?). After rupturing, it unfolds into a wing margin, which is circular in the ideal case and often displays an antapical point (bulge). The paratabulation with the exception of the transverse crest is usually smoothed out. The surface of the inner wall layer is exposed ventrally as “inner body”. Size: largest diameter 144-196 µm, length of inner body 75-98 µm.
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Original description: Eisenack, 1954, p. 71
Diagnosis: A mostly ellipsoidal (rarely spherical) central body with a rather firm wall is suspended in or coalescing with a helmet-, flat saucer- or bell-shaped, bi-layered membrane, in such a way, that the longitudinal axis of the ellipsoid continues in the membrane. Mostly, a low, approximately sharp-edged keel runs over the convex side of this membrane in the direction of the longitudinal axis, terminating in a short tip at the rear margin of the membrane. On the (upper) outside of the central body, a mostly horseshoe-shapes hatch is developed in the front half.
Dimensions: Holotype: oval: 81:69 Ám, membranes: ca. 170 Ám, tip ca. 10 Ám, hatch ca. 46 Ám. Length and width of the central body vary between 78-98 Ám and 60-78 Ám, the diameter of the membrane between 144 and 196 Ám. The height of the hatch between 36 and 46 Ám.
Gocht, 1969, p.66-68:
The Meckelfeld finds have furnished a major contribution to our knowledge of the type species T. pelagica and of the genus Thalassiphora in general. These have already been treated in a separate study (Gocht, 1968). In some samples from the Middle Oligocene, but especially in sample 15b, there was an almost unbroken series of transitional forms from the tabulate dinoflagellate (tabulation: 1', 1a, 5''-4''', 1'''', Lf.) to the winglike membrane (Th. pelagica in the old sense). This series indicates that the outer membrane of the dinoflagellates opened on the ventral side and the regular boundary folds between fields smoothed out gradually from ventral to dorsal. Eventually the outer membrane was only a weakly polygonal or circular wing attached to the dorsal side of the inner body. Usually the only remains of the areation were the cingular keel, and less frequently, the dorsal or antapical field boundaries. It can be assumed that the intermediate stages which were found represent actual gradations of a biological process, although its import remains obscure. Such observations are not limited to the Meckelfeld finds: Traces of areation or indications of an originally closed outer membrane have been found also on membranes from other sites. Also other species of the genus point in this direction. However, the "spur" formed by the outer membrane over the archeopyle, which probably was ejected only after the membrane opened on the ventral side, was not known previously. The presumptive sequence of ontogeny is reconstructed in figure 46. The fact that "unfolded" individuals and those which remain closed should definitely be regarded as conspecific made a revision of the genus and species necessary. Allowance had to be made for the not very satisfying situation that the diagnosis of the simpler wing- membranes would have to be expanded to include the much more highly differentiated closed membranes with constant areation and archeopyle spur. Such a step would never have been taken without the many transitional forms from Meckelfeld and independent observations on individuals from other sites which show the same trend. The infrequency or absence of the closed "dinoflagellate stage" in most Eocene or Oligocene samples, which often contained abundant wing-membranes, I explained by postulating that normally only the "final stage" is recovered. The closed membrane could only be recovered in special circumstances which intervene forcefully in the cycle. It remains to be seen whether similar processes can be discovered also in other species of Thalassiphora, which might be regarded as supporting the hypotheses offered here.
Thalassiphora pelagica (Eisenack, 1954b, p.71, pl.12, figs.17–18) Eisenack and Gocht, 1960, p.513–514.
Emendation: Benedek and Gocht, 1981, p.59–61, as Thalassiphora pelagica.
Holotype: Eisenack, 1954b, pl.12, fig.17. Originally Pterospermopsis (Appendix A), subsequently (and now) Thalassiphora, thirdly Disphaeria.
Lentin and Williams (1977b, p.54) retained this species in Thalassiphora. Taxonomic junior synonyms: Thalassiphora sueroi and Thalassiphora (as Disphaeria) balcanica, both according to Stover and Evitt (1978, p.194) — however, Sütő-Szentai (2000, p.162) retained Thalassiphora (as Spiniferites) balcanica; Pterocystidiopsis (as Thalassiphora) velata and Adnatosphaeridium (as Thalassiphora) patulum, both according to Benedek and Gocht (1981, p.59) — however, Lentin and Williams (1985, p.354) retained Thalassiphora patula and Brinkhuis and Biffi (1993, p.179) retained Pterocystidiopsis (as and now Thalassiphora) velata; Subathua sahnii, according to Lentin and Williams (1985, p.340) — however, Subathua sahnii is now considered to be a taxonomic junior synonym of Adnatosphaeridium (as and now Thalassiphora) patulum; Subathua spinosa, according to Lentin and Williams (1985, p.340) — however, Stover and Williams (1987, p.207) retained Subathua (as Thalassiphora) spinosa (now Thalassiphora simlaensis).
Locus typicus: Samlandt, E. Prussia, Russia
Stratum typicum: Early Oligocene
---------------------------------------------------------------------------------------------------
Translation Eisenack, 1954: LPP
Translation Gocht, 1969: Geological Survey of Canada
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Thalassiphora pelagica (Eisenack, 1954b) Eisenack and Gocht, 1960, emend. Benedek and Gocht, 1981. Emendation from Benedek and Gocht (1981, p.59-61), body polygonal, longer than wide, divided into fields through more or less steep border ridges. Cingulum slightly curved to the left, in the form of a simple crest. Longitudinal furrow unsegmented, occasionally with a flagellar pore. Lateral pre- and postcingular fields 1", 5", 2"’-5"’ large, polygonal. 2" and 4" slightly smaller, 6" narrow, rectangular, usually indistinctly demarcated from the sulcus. 3" developed as steep, spine-shaped projection, with horseshoe-shaped basis. 1" small, usually incorporated in the sulcal field. Dorsal (2',3') and ventral apical fields (1',4') separated by a crested fringe, but hardly demarcated from each other. Antapical field (1"”) large, polygonal, slightly inclined towards the longitudinal axis, often with central hump. Paratabulation 4', 6", 0c, 5"’, 1"”, s (border ridges 2'/3' and 4'/1', 6"/s and s/1"’/2"’ often not or only insufficiently marked). Archeopyle plate 3". Wall two-layered, of cellular-fibrous structure. Both wall layers merging without sharp demarcation. Inner and outer surface covered by a thin cover membrane (tectum). Wall cross-sections show a labyrinthic or reticular meshwork with thickened areas and pores. Inner tectum perforated. The inner wall layer interspersed with irregular but well demarcated cavities lying roughly in one plane. During the individual development the ventral outer layer of the wall is reduced to a thin lamina under the outer tectum (resorbed?). After rupturing, it unfolds into a wing margin, which is circular in the ideal case and often displays an antapical point (bulge). The paratabulation with the exception of the transverse crest is usually smoothed out. The surface of the inner wall layer is exposed ventrally as “inner body”. Size: largest diameter 144-196 µm, length of inner body 75-98 µm.
--------------------------------------------------
Original description: Eisenack, 1954, p. 71
Diagnosis: A mostly ellipsoidal (rarely spherical) central body with a rather firm wall is suspended in or coalescing with a helmet-, flat saucer- or bell-shaped, bi-layered membrane, in such a way, that the longitudinal axis of the ellipsoid continues in the membrane. Mostly, a low, approximately sharp-edged keel runs over the convex side of this membrane in the direction of the longitudinal axis, terminating in a short tip at the rear margin of the membrane. On the (upper) outside of the central body, a mostly horseshoe-shapes hatch is developed in the front half.
Dimensions: Holotype: oval: 81:69 Ám, membranes: ca. 170 Ám, tip ca. 10 Ám, hatch ca. 46 Ám. Length and width of the central body vary between 78-98 Ám and 60-78 Ám, the diameter of the membrane between 144 and 196 Ám. The height of the hatch between 36 and 46 Ám.
Gocht, 1969, p.66-68:
The Meckelfeld finds have furnished a major contribution to our knowledge of the type species T. pelagica and of the genus Thalassiphora in general. These have already been treated in a separate study (Gocht, 1968). In some samples from the Middle Oligocene, but especially in sample 15b, there was an almost unbroken series of transitional forms from the tabulate dinoflagellate (tabulation: 1', 1a, 5''-4''', 1'''', Lf.) to the winglike membrane (Th. pelagica in the old sense). This series indicates that the outer membrane of the dinoflagellates opened on the ventral side and the regular boundary folds between fields smoothed out gradually from ventral to dorsal. Eventually the outer membrane was only a weakly polygonal or circular wing attached to the dorsal side of the inner body. Usually the only remains of the areation were the cingular keel, and less frequently, the dorsal or antapical field boundaries. It can be assumed that the intermediate stages which were found represent actual gradations of a biological process, although its import remains obscure. Such observations are not limited to the Meckelfeld finds: Traces of areation or indications of an originally closed outer membrane have been found also on membranes from other sites. Also other species of the genus point in this direction. However, the "spur" formed by the outer membrane over the archeopyle, which probably was ejected only after the membrane opened on the ventral side, was not known previously. The presumptive sequence of ontogeny is reconstructed in figure 46. The fact that "unfolded" individuals and those which remain closed should definitely be regarded as conspecific made a revision of the genus and species necessary. Allowance had to be made for the not very satisfying situation that the diagnosis of the simpler wing- membranes would have to be expanded to include the much more highly differentiated closed membranes with constant areation and archeopyle spur. Such a step would never have been taken without the many transitional forms from Meckelfeld and independent observations on individuals from other sites which show the same trend. The infrequency or absence of the closed "dinoflagellate stage" in most Eocene or Oligocene samples, which often contained abundant wing-membranes, I explained by postulating that normally only the "final stage" is recovered. The closed membrane could only be recovered in special circumstances which intervene forcefully in the cycle. It remains to be seen whether similar processes can be discovered also in other species of Thalassiphora, which might be regarded as supporting the hypotheses offered here.