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Cleistosphaeridium iaculigerum
Cleistosphaeridium iaculigerum, (Klement, 1960), Brenner, 1988; Emendation: Sarjeant, 1984a, p.171, as Operculodinium? iaculigerum.
NOW Downiesphaeridium. Originally Baltisphaeridium (Appendix A), subsequently Operculodinium?, thirdly Cleistosphaeridium, fourthly (and now) Downiesphaeridium.
Taxonomic junior synonym: Cleistosphaeridium? polyacanthum, according to Brenner (1988, p.42) - however, Islam (1993, p.84) retained Cleistosphaeridium? (as Downiesphaeridium) polyacanthum.
Holotype: Klement, 1960, pl.7, fig.10; Sarjeant, 1984a, pl.2, fig.5; text-fig.7; Brenner, 1988, pl.14, fig.7; Fauconnier and Masure, 2004, pl.23, figs.4-5.
Locus typicus: Borehole Scherstetten 1
Stratum typicum: Malm-Lower Delta, South-west Germany
Age: Middle Kimmeridgian
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Original description as Baltisphaeridium iaculigerum: [Klement 1960, p. 57, 58]: (Translation: GSC)
Diagnosis:
A species of the genus Baltisphaeridium with spherical central shell, covered by numerous (30-40), awl-shaped, distally closed non-furcated processes of equal length (process length = about ⌀ the shell diameter).
Description:
This species could be documented only by four specimens which, on the one hand, were in an excellent state of preservation and, on the other hand, embodied a structural type which could not be found anywhere else in the available material.
The completely spherical central shell bears numerous, absolutely similar, stiff, seldom curved processes, the length of which is of an order of magnitude equaling approximately that of ⌀ of the shell diameter. These processes are awl-shaped, possess a circular cross-section and are distinctly broadened at their base; while continuously tapering down distally, these processes terminate in a sharp point, and are distally thickened in a knobular manner on rarer occasions. Moreover, the processes are always non-furcated and are definitely closed-off distally, though hollow as far as the rest is concerned. All representatives possessed in each instance an absolutely circularly delineated pylome.
The thin-walled membrane of the shell appears to be completely smooth and, in similar manner as the appendages, is of light yellow coloration.
Dimensions:
Shell (without processes)
processes diameter length
Holotype 35 µm 18 µm
paratypoid 29-31 µm 20 µm
Number of examined specimens: 4
Relationships:
This "trite or ordinary" construction type of spherical hystrichosphaeridiae, with completely non-differantiated, simple processes, is not represented very frequently in the Jurassic. As closest related species we might possibly consider the Baltisphaeridium polytrichum VALENSI (=Hystrichopshaeridium). However, the representatives of the latter possess a by far greater number of processes - and we quote from the French text "....it is covered by numerous processes which envelop it like fairly dense long hair..." (end of quote [which was not further identified here])--whereby said processes are distally covered, in part, with 3 - 4 fine filaments which are arranged in perpendicular manner with respect to the process. Furthermore, the shell is slightly flattened there and of an ellipsoidal form, whereas it is completely spherical in our case.
Considerable deviations from the Baltisphaeridium stimuliferum DEFLANDRE (=Hystrichosphaeridium) exist here as well, whereby we are referring to the processes which are still longer and thicker there than in our case and are present in much smaller numbers than here.
The Baltisphaeridium hirsutum EHRENBERG (=Hystrichosphaeridium) is another representative of this type. However, in this species the processes are shorter and lie closer to one another than in the species here under discussion.
NOW Downiesphaeridium. Originally Baltisphaeridium (Appendix A), subsequently Operculodinium?, thirdly Cleistosphaeridium, fourthly (and now) Downiesphaeridium.
Taxonomic junior synonym: Cleistosphaeridium? polyacanthum, according to Brenner (1988, p.42) - however, Islam (1993, p.84) retained Cleistosphaeridium? (as Downiesphaeridium) polyacanthum.
Holotype: Klement, 1960, pl.7, fig.10; Sarjeant, 1984a, pl.2, fig.5; text-fig.7; Brenner, 1988, pl.14, fig.7; Fauconnier and Masure, 2004, pl.23, figs.4-5.
Locus typicus: Borehole Scherstetten 1
Stratum typicum: Malm-Lower Delta, South-west Germany
Age: Middle Kimmeridgian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Baltisphaeridium iaculigerum: [Klement 1960, p. 57, 58]: (Translation: GSC)
Diagnosis:
A species of the genus Baltisphaeridium with spherical central shell, covered by numerous (30-40), awl-shaped, distally closed non-furcated processes of equal length (process length = about ⌀ the shell diameter).
Description:
This species could be documented only by four specimens which, on the one hand, were in an excellent state of preservation and, on the other hand, embodied a structural type which could not be found anywhere else in the available material.
The completely spherical central shell bears numerous, absolutely similar, stiff, seldom curved processes, the length of which is of an order of magnitude equaling approximately that of ⌀ of the shell diameter. These processes are awl-shaped, possess a circular cross-section and are distinctly broadened at their base; while continuously tapering down distally, these processes terminate in a sharp point, and are distally thickened in a knobular manner on rarer occasions. Moreover, the processes are always non-furcated and are definitely closed-off distally, though hollow as far as the rest is concerned. All representatives possessed in each instance an absolutely circularly delineated pylome.
The thin-walled membrane of the shell appears to be completely smooth and, in similar manner as the appendages, is of light yellow coloration.
Dimensions:
Shell (without processes)
processes diameter length
Holotype 35 µm 18 µm
paratypoid 29-31 µm 20 µm
Number of examined specimens: 4
Relationships:
This "trite or ordinary" construction type of spherical hystrichosphaeridiae, with completely non-differantiated, simple processes, is not represented very frequently in the Jurassic. As closest related species we might possibly consider the Baltisphaeridium polytrichum VALENSI (=Hystrichopshaeridium). However, the representatives of the latter possess a by far greater number of processes - and we quote from the French text "....it is covered by numerous processes which envelop it like fairly dense long hair..." (end of quote [which was not further identified here])--whereby said processes are distally covered, in part, with 3 - 4 fine filaments which are arranged in perpendicular manner with respect to the process. Furthermore, the shell is slightly flattened there and of an ellipsoidal form, whereas it is completely spherical in our case.
Considerable deviations from the Baltisphaeridium stimuliferum DEFLANDRE (=Hystrichosphaeridium) exist here as well, whereby we are referring to the processes which are still longer and thicker there than in our case and are present in much smaller numbers than here.
The Baltisphaeridium hirsutum EHRENBERG (=Hystrichosphaeridium) is another representative of this type. However, in this species the processes are shorter and lie closer to one another than in the species here under discussion.