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Operculodinium hirsutum
Operculodinium? hirsutum (Ehrenberg, 1838) Lentin and Williams, 1973
Name not validly published since Ehrenberg, 1838, did not intend to introduce a new species.
Originally Xanthidium hirsutum (name not validly published), subsequently Ovum hispidum ssp. hirsutum (name not validly published), thirdly Hystrichosphaera hirsuta (name not validly published), fourthly Hystrichosphaeridium hirsutum (name not validly published), fifthly Baltisphaeridium hirsutum (name not validly published), sixthly Operculodinium hirsutum (name not validly published), seventhly Operculodinium? hirsutum (name not validly published).
According to Fensome et al., 1990, "It is apparent from the discussion given by Sarjeant, 1984, that Ehrenberg, 1838, did not intend to introduce a new taxon but was comparing fossil specimens with Xanthidium (now Staurastrum) hirsutum Ehrenberg, 1838, a species of extant desmids. Thus the microfossil species name Xanthidium hirsutum and derivatives (Hystrichosphaeridium hirsutum, Hystrichosphaera hirsuta and Operculodinium hirsutum) are not validly published according to I.C.B.N. Article 34.1a. The specimen illustrated and provisionally identified as Xanthidium hirsutum by Ehrenberg (1838) is a specimen of Coronifera striolata ... according to Sarjeant, 1984."
Stover and Evitt, 1978, considered this to be a provisionally accepted species of Operculodinium.
Age: Cretaceous
Translation Gocht, 1969: Geological Survey of Canada
Gocht, 1969, p.51,52:
Operculodinium cf. hirsutum (Ehrenberg, 1836)
The finds from Meckelfeld alone already show the variability of this group, which has entered the literature under various species names. Exact definitions or synonymy can not yet be given. Even the classification in Wall"s genus Operculodinium is somewhat uncertain, especially since some variants show also a polar orientation. The majority of the objects conform to the finds described by Cookson and Hughes, 1954 from the Cambridge Green Sand, and perhaps even more to "Hystrichosphaeridium microtriaina " Klumpp, 1953, which also belongs to this formenkreis. The body form is usually of spherical shape, although almost always, it is flattened into a disk. Like Cordosphaeridium, this form has two layers, and the outer layer shows a fibrous structure. This structure, which has considerable influence on the appearance of the specimen, can take the form of large strands or it can be reduced to a fine reticulum. However, especially in the Middle Oligocene samples, in which both types and intermediate forms occur, the affinity is clear. Also the greatest dimensions are reached in these samples.
The processes are numerous, slender, long, and distally slightly thickened or perpendicularly truncate, occasionally with a trace of a furcation. Some are fused from the base halfway up. Also "bridges" may be formed at the base: The shafts divide into strands still above the main body, which then radiate over the surface and expire. A space with perforated walls lies directly below the shaft. Above, the shafts always become solid and hyaline, and the longitudinal fibrous structure is no longer visible. The archeopyle was clearly observable only on a few specimens. On the flattened ones, there is usually only an irregular or triangular opening. The unflattened archeopyle is horseshoe-shaped.
Some specimens are distinctly polar: The body is elongate lengthwise and bears a short "horn" at the apex. Also the processes at the poles are usually larger and frequently fused together in one plane. The number of processes on such specimens can be very high. Although the typical, branched apical process was not observed here, the similarity with some Lanternosphaeridium species is unmistakable. "Normally" shaped individuals vary mainly in size and surface structure, but the number and spacing of processes is quite variable also in this material.
Measurements : Maximal extension 106-165 Ám. Central body diameter 57-100 Ám.
Occurrence: Early Eocene- Middle Oligocene.
Name not validly published since Ehrenberg, 1838, did not intend to introduce a new species.
Originally Xanthidium hirsutum (name not validly published), subsequently Ovum hispidum ssp. hirsutum (name not validly published), thirdly Hystrichosphaera hirsuta (name not validly published), fourthly Hystrichosphaeridium hirsutum (name not validly published), fifthly Baltisphaeridium hirsutum (name not validly published), sixthly Operculodinium hirsutum (name not validly published), seventhly Operculodinium? hirsutum (name not validly published).
According to Fensome et al., 1990, "It is apparent from the discussion given by Sarjeant, 1984, that Ehrenberg, 1838, did not intend to introduce a new taxon but was comparing fossil specimens with Xanthidium (now Staurastrum) hirsutum Ehrenberg, 1838, a species of extant desmids. Thus the microfossil species name Xanthidium hirsutum and derivatives (Hystrichosphaeridium hirsutum, Hystrichosphaera hirsuta and Operculodinium hirsutum) are not validly published according to I.C.B.N. Article 34.1a. The specimen illustrated and provisionally identified as Xanthidium hirsutum by Ehrenberg (1838) is a specimen of Coronifera striolata ... according to Sarjeant, 1984."
Stover and Evitt, 1978, considered this to be a provisionally accepted species of Operculodinium.
Age: Cretaceous
Translation Gocht, 1969: Geological Survey of Canada
Gocht, 1969, p.51,52:
Operculodinium cf. hirsutum (Ehrenberg, 1836)
The finds from Meckelfeld alone already show the variability of this group, which has entered the literature under various species names. Exact definitions or synonymy can not yet be given. Even the classification in Wall"s genus Operculodinium is somewhat uncertain, especially since some variants show also a polar orientation. The majority of the objects conform to the finds described by Cookson and Hughes, 1954 from the Cambridge Green Sand, and perhaps even more to "Hystrichosphaeridium microtriaina " Klumpp, 1953, which also belongs to this formenkreis. The body form is usually of spherical shape, although almost always, it is flattened into a disk. Like Cordosphaeridium, this form has two layers, and the outer layer shows a fibrous structure. This structure, which has considerable influence on the appearance of the specimen, can take the form of large strands or it can be reduced to a fine reticulum. However, especially in the Middle Oligocene samples, in which both types and intermediate forms occur, the affinity is clear. Also the greatest dimensions are reached in these samples.
The processes are numerous, slender, long, and distally slightly thickened or perpendicularly truncate, occasionally with a trace of a furcation. Some are fused from the base halfway up. Also "bridges" may be formed at the base: The shafts divide into strands still above the main body, which then radiate over the surface and expire. A space with perforated walls lies directly below the shaft. Above, the shafts always become solid and hyaline, and the longitudinal fibrous structure is no longer visible. The archeopyle was clearly observable only on a few specimens. On the flattened ones, there is usually only an irregular or triangular opening. The unflattened archeopyle is horseshoe-shaped.
Some specimens are distinctly polar: The body is elongate lengthwise and bears a short "horn" at the apex. Also the processes at the poles are usually larger and frequently fused together in one plane. The number of processes on such specimens can be very high. Although the typical, branched apical process was not observed here, the similarity with some Lanternosphaeridium species is unmistakable. "Normally" shaped individuals vary mainly in size and surface structure, but the number and spacing of processes is quite variable also in this material.
Measurements : Maximal extension 106-165 Ám. Central body diameter 57-100 Ám.
Occurrence: Early Eocene- Middle Oligocene.