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Wetzeliella symmetrica
Wetzeliella symmetrica Weiler, 1956, p.132-135
Taxonomic junior synonym: Hystrichosphaeridium saturnium, according to Sarjeant (1983, p.107–108).
Holotype: Weiler, 1956, pl.11, fig.1
Age: Middle Oligocene
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
Wetzeliella symmetrica Weiler, 1956, appears to have a soleiform archeopyle and four more or less equal horns. The peri- and endoarcheopyle are of the same size and in the same position. The endocyst is rhomboidal and lies close to the pericyst although there is a narrow ambital pericoel. The processes are distally bifid or aculeate. Size: length 120-185 µm, width 114-175 µm, archeopyle 33 µm long and 28 µm wide.
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Weiler 1956, p. 132: Wetzeliella symmetrica
Diagnosis: Flattened central body with rhomboidal, not totally square outline. At the four corners horns are present. None of the horns shows a more favoured growth. No indications for transverse or longitudinal furrows are present. The shell is transparent, smooth and resistant against mechanical pression. The dark coloured inner capsule does not touch the outer wall of the shell anywhere. The shell and horns are regularly ornamented by slender, similar shaped processes. The processes are hollow and distally forked into 2-4 scaly branches.
Dimensions: length and breadth: 165-180 Ám.
Descriptions (translated from German and shortened): Ca. 400 specimens are studied. In all specimens the outline is equal. The fossils are always recognisable by their square form. Only minor variation is observed. The development of a fifth horn was not observed. The inner capsules (present in all specimens) are almost square with rounded corners, sometimes the roundening results in an almost circular outline. Always a cavity is present between inner capsule and outer wall.
Striking is the presence of archeopyles, which has a pear-shaped outline in all specimens. The blunt end is ¦ outside the centre of the capsule, the broadest part is about two-third the length.
Affinities:
Weiler 1956, p. 132-133: Wetzeliella symmetrica.
The here described species differs distinctly from W.articulata, which resembles most to the description, by the continuous build-up of only four horns. The horns are also of equal size, in contrast to other species in this genus.
Gocht, 1969, p.23:
Wetzeliella symmetrica was found quite frequently in Oligocene samples, and only there. For comparison, I had originals from Weiler and Gerlach and finds from the Fischschiefer core drilled in Werrabronn (Weingarten). The latter sample, in particular, from the type stratum of the species, yielded numerous and very uniformly structured specimens which correspond fully with Weiler's originals. The finds at Meckelfeld, however, were more variable; some are intermediate between typical forms and those which Gerlach, 1961 described as subspecies incisa, on which the horns are usually less sharply acuminate or even quite irregularly shaped.
The antapical part tends to be asymmetrical and often still shows traces of a second horn. Gerlach has already called attention to this variability. Alberti, 1961 even mentions transitional forms between W. symmetrica and W. articulata. Another variation from Meckelfeld is described in my next entry. Once again, then, we are concerned with an entire formenkreis. It is fairly certain that there is no direct relationship with W. meckelfeldensis (the form described by Williams and Downie, 1966 as W. symmetrica belongs to Meckelfeldensis).
The rhomboid outline and the characteristic coating of processes usually differentiate the group well; the reader is referred especially to the illustrations, which convey these features better than the description.
Archeopyles as actual openings are not very frequent. This applies to Meckelfeld and Werrabronn, and surprisingly, the same is reported by Weiler and Gerlach. The inner pylome does not seem to be noticeably smaller than the outer.
The inner body frequently shows flocculent deposits of organic substance, especially under the horns. The flagellar insertions are pitted to sievelike and elongate.
Occurrence: Middle Oligocene.
Wetzeliella symmetrica var. Gocht, 1969
Plate 10, fig. 7 and 11
This form has a pentangular outline and two antapical horns. Otherwise, it does not appear different from W. symmetrica, together with which it occurs. Invididual specimens are intermediate between the two forms. The processes are usually somewhat shorter than the typical form. The inner body is tightly appressed to the outer membrane. Assignment of this form to W. symmetrica is especially difficult because the expanded diagnosis would have to sacrifice the principal character, viz., the rhomboid shape. On the other hand, the situation in nature must not be glossed over. In view of many similar cases- specifically among Wetzeliella spp.- the decision will be left open for the present.
Occurrence: Middle Oligocene.
Taxonomic junior synonym: Hystrichosphaeridium saturnium, according to Sarjeant (1983, p.107–108).
Holotype: Weiler, 1956, pl.11, fig.1
Age: Middle Oligocene
Translation Gocht, 1969: Geological Survey of Canada
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Wetzeliella symmetrica Weiler, 1956, appears to have a soleiform archeopyle and four more or less equal horns. The peri- and endoarcheopyle are of the same size and in the same position. The endocyst is rhomboidal and lies close to the pericyst although there is a narrow ambital pericoel. The processes are distally bifid or aculeate. Size: length 120-185 µm, width 114-175 µm, archeopyle 33 µm long and 28 µm wide.
--------------------------------------------------
Weiler 1956, p. 132: Wetzeliella symmetrica
Diagnosis: Flattened central body with rhomboidal, not totally square outline. At the four corners horns are present. None of the horns shows a more favoured growth. No indications for transverse or longitudinal furrows are present. The shell is transparent, smooth and resistant against mechanical pression. The dark coloured inner capsule does not touch the outer wall of the shell anywhere. The shell and horns are regularly ornamented by slender, similar shaped processes. The processes are hollow and distally forked into 2-4 scaly branches.
Dimensions: length and breadth: 165-180 Ám.
Descriptions (translated from German and shortened): Ca. 400 specimens are studied. In all specimens the outline is equal. The fossils are always recognisable by their square form. Only minor variation is observed. The development of a fifth horn was not observed. The inner capsules (present in all specimens) are almost square with rounded corners, sometimes the roundening results in an almost circular outline. Always a cavity is present between inner capsule and outer wall.
Striking is the presence of archeopyles, which has a pear-shaped outline in all specimens. The blunt end is ¦ outside the centre of the capsule, the broadest part is about two-third the length.
Affinities:
Weiler 1956, p. 132-133: Wetzeliella symmetrica.
The here described species differs distinctly from W.articulata, which resembles most to the description, by the continuous build-up of only four horns. The horns are also of equal size, in contrast to other species in this genus.
Gocht, 1969, p.23:
Wetzeliella symmetrica was found quite frequently in Oligocene samples, and only there. For comparison, I had originals from Weiler and Gerlach and finds from the Fischschiefer core drilled in Werrabronn (Weingarten). The latter sample, in particular, from the type stratum of the species, yielded numerous and very uniformly structured specimens which correspond fully with Weiler's originals. The finds at Meckelfeld, however, were more variable; some are intermediate between typical forms and those which Gerlach, 1961 described as subspecies incisa, on which the horns are usually less sharply acuminate or even quite irregularly shaped.
The antapical part tends to be asymmetrical and often still shows traces of a second horn. Gerlach has already called attention to this variability. Alberti, 1961 even mentions transitional forms between W. symmetrica and W. articulata. Another variation from Meckelfeld is described in my next entry. Once again, then, we are concerned with an entire formenkreis. It is fairly certain that there is no direct relationship with W. meckelfeldensis (the form described by Williams and Downie, 1966 as W. symmetrica belongs to Meckelfeldensis).
The rhomboid outline and the characteristic coating of processes usually differentiate the group well; the reader is referred especially to the illustrations, which convey these features better than the description.
Archeopyles as actual openings are not very frequent. This applies to Meckelfeld and Werrabronn, and surprisingly, the same is reported by Weiler and Gerlach. The inner pylome does not seem to be noticeably smaller than the outer.
The inner body frequently shows flocculent deposits of organic substance, especially under the horns. The flagellar insertions are pitted to sievelike and elongate.
Occurrence: Middle Oligocene.
Wetzeliella symmetrica var. Gocht, 1969
Plate 10, fig. 7 and 11
This form has a pentangular outline and two antapical horns. Otherwise, it does not appear different from W. symmetrica, together with which it occurs. Invididual specimens are intermediate between the two forms. The processes are usually somewhat shorter than the typical form. The inner body is tightly appressed to the outer membrane. Assignment of this form to W. symmetrica is especially difficult because the expanded diagnosis would have to sacrifice the principal character, viz., the rhomboid shape. On the other hand, the situation in nature must not be glossed over. In view of many similar cases- specifically among Wetzeliella spp.- the decision will be left open for the present.
Occurrence: Middle Oligocene.