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Downiesphaeridium iaculigerum
From Fensome et al., 2019:
Downiesphaeridium iaculigerum (Klement, 1960, p.57–58, pl.7, fig.10) Williams et al., 1998, p.203. Emendation: Sarjeant, 1984a, p.171, as Operculodinium? iaculigerum. Holotype: Klement, 1960, pl.7, fig.10; Sarjeant, 1984a, pl.2, fig.5; textfig. 7; Brenner, 1988, pl.14, fig.7; Fauconnier and Masure, 2004, pl.23, figs.4–5. 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. Age: middle Kimmeridgian.
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Original description (Klement, 1960) (translated from German):
Baltisphaeridium iaculigerum n. sp.
Plate 7, Fig. 10
Holotype: Pr 1149/87 (S 33/17): Plate 7, Fig. 10.
Paratypoids: Pr 1149/88 (S 36/57).
Typical location: Scherstetten 1 borehole.
Typical stratum: Malm Lower Delta; core between 1682.3 and 1683.6 m.
Nominal derivation: iaculum = spear; due to the slender, distally tapering processes.
Diagnosis: A species of the genus Baltisphaeridium with a spherical central shell covered by numerous (30 to 40) equally long (about 1/2 shell diameter), awl-shaped, distally closed, and unforked processes.
Description: This species could only be documented by four specimens, one of which is very well preserved and the other represents a structural type no longer represented in the available material.
The completely spherical central shell bears numerous, absolutely uniformly developed, stiff, rarely bent processes, the length of which is approximately half the shell diameter. They are awl-shaped, circular in cross-section, distinctly widened at the base, and gradually taper distally to a point, rarely with a knob-shaped thickening. The processes are always unforked and are clearly closed at the end, but hollow throughout the rest of their length.
All specimens exhibited a completely circular pyloma.
The delicate-walled membrane of the shell appears completely smooth and, like the appendages, is light yellow in color.
Relationships: This banal structural type of spherical Hystrichosphaeridae with completely undifferentiated, simple processes is not very common in the Jurassic. The closest species is Baltisphaeridium polytrichum VALENSI [= Hystrichosphaeridium]. However, its representatives have far more numerous processes ("... it is covered with numerous processes which are enveloped by a long, dense hair."), some of which are distally covered with three to four fine threads arranged perpendicular to the process. Furthermore, the sheath in this case has a slightly flattened, ellipsoidal shape, whereas here it is completely spherical.
Similarly, there are considerable differences compared to Baltisphaeridium stimuliferum DEFLANDRE [= Hystrichosphaeridium] with regard to the even longer, coarser, and far fewer numerous appendages.
Another representative of this type is Baltisphaeridium hirsutum (EHRENBERG) [= Hystrichosphaeridium]. In this species, however, the processes are denser and shorter than in the preceding one.
Occurrence: Scherstetten 1: Samples No. S 36, S 33, i.e., in the Malm Gamma and Lower Delta.
Hörnle (Neuffen): No. N 386 (Lower Gamma): Single find.
Bäratalsteige: No. B1 (Upper Gamma): Single find.
Dimensions: Shell
(without appendages) Diameter Appendages (length)
Holotype: 35 18
Paratypoid: 29-31 20
Number of specimens examined: 4.
Downiesphaeridium iaculigerum (Klement, 1960, p.57–58, pl.7, fig.10) Williams et al., 1998, p.203. Emendation: Sarjeant, 1984a, p.171, as Operculodinium? iaculigerum. Holotype: Klement, 1960, pl.7, fig.10; Sarjeant, 1984a, pl.2, fig.5; textfig. 7; Brenner, 1988, pl.14, fig.7; Fauconnier and Masure, 2004, pl.23, figs.4–5. 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. Age: middle Kimmeridgian.
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Original description (Klement, 1960) (translated from German):
Baltisphaeridium iaculigerum n. sp.
Plate 7, Fig. 10
Holotype: Pr 1149/87 (S 33/17): Plate 7, Fig. 10.
Paratypoids: Pr 1149/88 (S 36/57).
Typical location: Scherstetten 1 borehole.
Typical stratum: Malm Lower Delta; core between 1682.3 and 1683.6 m.
Nominal derivation: iaculum = spear; due to the slender, distally tapering processes.
Diagnosis: A species of the genus Baltisphaeridium with a spherical central shell covered by numerous (30 to 40) equally long (about 1/2 shell diameter), awl-shaped, distally closed, and unforked processes.
Description: This species could only be documented by four specimens, one of which is very well preserved and the other represents a structural type no longer represented in the available material.
The completely spherical central shell bears numerous, absolutely uniformly developed, stiff, rarely bent processes, the length of which is approximately half the shell diameter. They are awl-shaped, circular in cross-section, distinctly widened at the base, and gradually taper distally to a point, rarely with a knob-shaped thickening. The processes are always unforked and are clearly closed at the end, but hollow throughout the rest of their length.
All specimens exhibited a completely circular pyloma.
The delicate-walled membrane of the shell appears completely smooth and, like the appendages, is light yellow in color.
Relationships: This banal structural type of spherical Hystrichosphaeridae with completely undifferentiated, simple processes is not very common in the Jurassic. The closest species is Baltisphaeridium polytrichum VALENSI [= Hystrichosphaeridium]. However, its representatives have far more numerous processes ("... it is covered with numerous processes which are enveloped by a long, dense hair."), some of which are distally covered with three to four fine threads arranged perpendicular to the process. Furthermore, the sheath in this case has a slightly flattened, ellipsoidal shape, whereas here it is completely spherical.
Similarly, there are considerable differences compared to Baltisphaeridium stimuliferum DEFLANDRE [= Hystrichosphaeridium] with regard to the even longer, coarser, and far fewer numerous appendages.
Another representative of this type is Baltisphaeridium hirsutum (EHRENBERG) [= Hystrichosphaeridium]. In this species, however, the processes are denser and shorter than in the preceding one.
Occurrence: Scherstetten 1: Samples No. S 36, S 33, i.e., in the Malm Gamma and Lower Delta.
Hörnle (Neuffen): No. N 386 (Lower Gamma): Single find.
Bäratalsteige: No. B1 (Upper Gamma): Single find.
Dimensions: Shell
(without appendages) Diameter Appendages (length)
Holotype: 35 18
Paratypoid: 29-31 20
Number of specimens examined: 4.