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Operculodinium iaculigerum
Operculodinium? iaculigerum (Klement, 1960); Emendation: Sarjeant, 1984a, p.171, as Operculodinium? iaculigerum.
NOW Downiesphaeridium. Originally Baltisphaeridium, subsequently Operculodinium?, thirdly Cleistosphaeridium, fourthly (and now) Downiesphaeridium. Questionable assignment: Sarjeant (1984a, p.171).
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; Fauconnier and Masure, 2004, pl.23, figs.4–5.
Paratype: Klement, 1960
Locus typicus: Borehole Scherstetten, SW Germany
Stratum typicum: Middle Kimmeridgian
Translation Klement, 1960: LPP
Original description: Klement, 1960, p. 57-58: Baltisphaeridium iaculigerum
Diagnosis: A species of the genus Baltisphaeridium with spherical central shell, set with numerous (30-40) equally long (c. 1/2 of the shell diameter), piercer-shaped, distally closed and nonfurcate processes.
Description (annotated): This species could be documented with only 4 specimens, which, however, were well-preserved and represented a type that was not encountered beyond the material in question.
The completely spherical central shell bears numerous, entirely similarly developed, rigid, rarely bent processes, the length of which amounts to about 1/2 of the central shell diameter. They are built in a piercer-shaped fashion, of a circular cross-section, at the base clealy widened, and, narrowing constantly, become pointed or rarely capitate distally. The processes are always nonfurcate and distally unequivocally closed, but otherwise hollow. In all representatives a completely circular pylome was encountered. The delicate membrane of the shell appears completely smooth.
Dimensions: holotype: shell (without processes) 35 Ám, process length 18 Ám; paratype: shell (without processes) 29-31 Ám, process length 20 Ám. 4 specimens studied.
Emended diagnosis: Sarjeant, 1984, p. 173
Cyst almost spheroidal, chorate. Processes simple, slender, tapering gently from base to tip. The number of processes is moderately low (30-50) and their distribution not uniform, suggesting a possible gonal and intergonal arrangement. length of processes 40-50% of the cyst diameter. Archaeopyle single-plate precingular, Type P.
Affinities:
Klement, 1960, p. 58: Baltisphaeridium iaculigerum
(annotated) This ordinary type of spherical Hystrichosphaerids with completely undifferentiated, simple processes is not very common in the Jurassic. The most closely related species would be Baltisphaeridium polytrichum Valensi (=Hystrichosphaeridium). Its representatives possess, however, even more numerous processes, which are distally set with 3-4 thin fibres, perpendicular to the process. Furthermore, its shell is slightly flattened ellipsoidal.
Also Baltisphaeridium stimuliferum Deflandre (=Hystrichosphaeridium) considerably diverges, with respect to its even longer, firm and considerably less numerous processes.
A further representative of this type is Baltisphaeridium hirsutum (Ehrenberg) (=Hystrichosphaeridium). In this species the processes are denser and shorter than in B. iaculigerum.
Sarjeant, 1984, p. 171-172
(annotated) The presence of a polygonal archaeopyle in the holotype permits its recognition as a dinoflagellete cyst. Its size and shape and the lack of either a sulcal notch or accessory sutures combine to indicate that the archaeopyle was formed by loss of a single plate precingular paraplate.
The number of processes is, for a chorate cyst with simple processes, relatively low and their distribution unequal. They do not appear to be nontabular, and yet the equivalence of their position to parasutures could not be confirmed. Spiniferate dinoflagellate cysts only become prominent in the Early Cretaceous; no other reliable records exist for such forms so early in the Late Jurassic. On the other hand, chorate cysts having the combination of nontabular processes and a single-plate precingular archaeopyle are not known earlier than the Late Cretaceous.
NOW Downiesphaeridium. Originally Baltisphaeridium, subsequently Operculodinium?, thirdly Cleistosphaeridium, fourthly (and now) Downiesphaeridium. Questionable assignment: Sarjeant (1984a, p.171).
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; Fauconnier and Masure, 2004, pl.23, figs.4–5.
Paratype: Klement, 1960
Locus typicus: Borehole Scherstetten, SW Germany
Stratum typicum: Middle Kimmeridgian
Translation Klement, 1960: LPP
Original description: Klement, 1960, p. 57-58: Baltisphaeridium iaculigerum
Diagnosis: A species of the genus Baltisphaeridium with spherical central shell, set with numerous (30-40) equally long (c. 1/2 of the shell diameter), piercer-shaped, distally closed and nonfurcate processes.
Description (annotated): This species could be documented with only 4 specimens, which, however, were well-preserved and represented a type that was not encountered beyond the material in question.
The completely spherical central shell bears numerous, entirely similarly developed, rigid, rarely bent processes, the length of which amounts to about 1/2 of the central shell diameter. They are built in a piercer-shaped fashion, of a circular cross-section, at the base clealy widened, and, narrowing constantly, become pointed or rarely capitate distally. The processes are always nonfurcate and distally unequivocally closed, but otherwise hollow. In all representatives a completely circular pylome was encountered. The delicate membrane of the shell appears completely smooth.
Dimensions: holotype: shell (without processes) 35 Ám, process length 18 Ám; paratype: shell (without processes) 29-31 Ám, process length 20 Ám. 4 specimens studied.
Emended diagnosis: Sarjeant, 1984, p. 173
Cyst almost spheroidal, chorate. Processes simple, slender, tapering gently from base to tip. The number of processes is moderately low (30-50) and their distribution not uniform, suggesting a possible gonal and intergonal arrangement. length of processes 40-50% of the cyst diameter. Archaeopyle single-plate precingular, Type P.
Affinities:
Klement, 1960, p. 58: Baltisphaeridium iaculigerum
(annotated) This ordinary type of spherical Hystrichosphaerids with completely undifferentiated, simple processes is not very common in the Jurassic. The most closely related species would be Baltisphaeridium polytrichum Valensi (=Hystrichosphaeridium). Its representatives possess, however, even more numerous processes, which are distally set with 3-4 thin fibres, perpendicular to the process. Furthermore, its shell is slightly flattened ellipsoidal.
Also Baltisphaeridium stimuliferum Deflandre (=Hystrichosphaeridium) considerably diverges, with respect to its even longer, firm and considerably less numerous processes.
A further representative of this type is Baltisphaeridium hirsutum (Ehrenberg) (=Hystrichosphaeridium). In this species the processes are denser and shorter than in B. iaculigerum.
Sarjeant, 1984, p. 171-172
(annotated) The presence of a polygonal archaeopyle in the holotype permits its recognition as a dinoflagellete cyst. Its size and shape and the lack of either a sulcal notch or accessory sutures combine to indicate that the archaeopyle was formed by loss of a single plate precingular paraplate.
The number of processes is, for a chorate cyst with simple processes, relatively low and their distribution unequal. They do not appear to be nontabular, and yet the equivalence of their position to parasutures could not be confirmed. Spiniferate dinoflagellate cysts only become prominent in the Early Cretaceous; no other reliable records exist for such forms so early in the Late Jurassic. On the other hand, chorate cysts having the combination of nontabular processes and a single-plate precingular archaeopyle are not known earlier than the Late Cretaceous.