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Litosphaeridium parvum
Litosphaeridium? parvum Matsuoka and Bujak, 1988
Matsuoka and Bujak, 1988, questionably included this species in Litosphaeridium.
Taxonomic senior synonym: Minisphaeridium latirictum, according to Fensome et al. (2009, p.44).
Holotype: Matsuoka and Bujak, 1988, pl.8, fig.2, text-fig.12
Paratypes: Matsuoka and Bujak, 1988
Locus typicus: Navarin Basin COST No. 1 Well, central Berina Sea
Stratum typicum: Heterculacacysta campanula Zone; Late Oligocene-Early Miocene
Original diagnosis: Matsuoka and Bujak, 1988, p.62
Small proximate cyst with a spherical to subspherical central body comprising two wall layers. Endopharagm thin and smooth; periphragm finely granular. Processes intratabular, hollow, broad, short, cylindrical to tubiferum with mostly entire to slightly recurved and open distal extremities. Processes distributing at the apical, precingular, postcingular, posterior intercalary and antapical regions, with a few processes on the parasulcus. Paracingular processes lacking. Parasutures absent. Paratabulation indicated by processes and archeopyle sutures as 4", 6", 0c, 6""", 1p, 1"""" and 0-2 (?) s. Archeopyle apical, possessing several archeopyle sutures, and comprising four paraplates.
Original description: Matsuoka and Bujak, 1988, p.62-63
The cyst wall consists of a smooth thin periphragm which is adpressed to the endophragm between the processes. The two walls are neither spongy nor fibrous. The processes are smooth and variable in diameter and distal morphology. The four apical and probably the posterior intercalary processes are sometimes smaller than the remaining processes. The distal extremities of the processes vary from entire to slightly recurved, but this feature is constant on a single specimen. The archeopyle is apical and is formed by the loss of four apical paraplates. It is not known whether the operculum is simple or compound.
Dimensions: Holotype; diameter of central body 19x21 µm, length of processes 8 µm, Range; diameter of central body 18x21-21x22 µm, length of processes 5-8 µm. Number of specimens measured: 5.
Thecal affinities: Unknown, possibly a member of the Gonyaulax lineage based on its paratabulation.
Affinities:
Matsuoka and Bujak, 1988, p.63: This species is provisionally assigned to the genus Litosphaeridium because of its apical archeopyle, lack of paracingular processes, and small cyst body.
? Litosphaeridium parvum differs from species of Hystrichosphaeridium in lacking cingular processes and from species of Cordosphaeridium in having an apical archeopyle and in lacking a fibrous periphragm and processes.
? L. parvum is similar to Dinocyst IV of Manum, 1976, which was recorded from middle-upper Oligocene to middle Miocene sediments of the Norwegian-Greenland Sea, in forming an apical archeopyle and in having a small cyst body. ? L. parvum differs from Dinocyst IV of Manum in possessing tubiform processes and a smooth periphragm. It is possible that the two species are conspecific, because the shape of processes is more variable in specimens from the Bering Sea. Dinocyst II of Manum, 1976 also differs from ? L. parvum is possibly forming a precingular archeopyle.
Matsuoka and Bujak, 1988, questionably included this species in Litosphaeridium.
Taxonomic senior synonym: Minisphaeridium latirictum, according to Fensome et al. (2009, p.44).
Holotype: Matsuoka and Bujak, 1988, pl.8, fig.2, text-fig.12
Paratypes: Matsuoka and Bujak, 1988
Locus typicus: Navarin Basin COST No. 1 Well, central Berina Sea
Stratum typicum: Heterculacacysta campanula Zone; Late Oligocene-Early Miocene
Original diagnosis: Matsuoka and Bujak, 1988, p.62
Small proximate cyst with a spherical to subspherical central body comprising two wall layers. Endopharagm thin and smooth; periphragm finely granular. Processes intratabular, hollow, broad, short, cylindrical to tubiferum with mostly entire to slightly recurved and open distal extremities. Processes distributing at the apical, precingular, postcingular, posterior intercalary and antapical regions, with a few processes on the parasulcus. Paracingular processes lacking. Parasutures absent. Paratabulation indicated by processes and archeopyle sutures as 4", 6", 0c, 6""", 1p, 1"""" and 0-2 (?) s. Archeopyle apical, possessing several archeopyle sutures, and comprising four paraplates.
Original description: Matsuoka and Bujak, 1988, p.62-63
The cyst wall consists of a smooth thin periphragm which is adpressed to the endophragm between the processes. The two walls are neither spongy nor fibrous. The processes are smooth and variable in diameter and distal morphology. The four apical and probably the posterior intercalary processes are sometimes smaller than the remaining processes. The distal extremities of the processes vary from entire to slightly recurved, but this feature is constant on a single specimen. The archeopyle is apical and is formed by the loss of four apical paraplates. It is not known whether the operculum is simple or compound.
Dimensions: Holotype; diameter of central body 19x21 µm, length of processes 8 µm, Range; diameter of central body 18x21-21x22 µm, length of processes 5-8 µm. Number of specimens measured: 5.
Thecal affinities: Unknown, possibly a member of the Gonyaulax lineage based on its paratabulation.
Affinities:
Matsuoka and Bujak, 1988, p.63: This species is provisionally assigned to the genus Litosphaeridium because of its apical archeopyle, lack of paracingular processes, and small cyst body.
? Litosphaeridium parvum differs from species of Hystrichosphaeridium in lacking cingular processes and from species of Cordosphaeridium in having an apical archeopyle and in lacking a fibrous periphragm and processes.
? L. parvum is similar to Dinocyst IV of Manum, 1976, which was recorded from middle-upper Oligocene to middle Miocene sediments of the Norwegian-Greenland Sea, in forming an apical archeopyle and in having a small cyst body. ? L. parvum differs from Dinocyst IV of Manum in possessing tubiform processes and a smooth periphragm. It is possible that the two species are conspecific, because the shape of processes is more variable in specimens from the Bering Sea. Dinocyst II of Manum, 1976 also differs from ? L. parvum is possibly forming a precingular archeopyle.