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Oligosphaeridium
From Williams et al., 2017:
[Oligosphaeridium, Davey and Williams, 1966b, p. 70-71; Emendation: Davey, 1982b, p.13
Type species: originally as Xanthidium tubiferum var. complex, White, 1842 (pl.4, fig.11) ; Neotype: Davey and Williams, 1966b (pl.7, fig.1), designated by Davey and Williams (1966b, p.71)]
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Original description: [Davey and Williams, 1966]:
Diagnosis:
Subspherical chorate cyst possessing a reflected tabulation of 4`, 6``, 5-6```, 1p, 1````. Processes tubiform, open distally, intratabular, one process per plate area. Number of processes never more than 18. Archaeopyle apical.
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Modified description:
Stover and Evitt 1978, p. 68-69:
Synopsis:
Cysts skolochorate, gonyaulacacean; body subspherical with 18 - 21 hollow cylindrical to tubiform intratabular processes that are generally open and normally expanded distally; cingular processes absent; archeopyle apical, Type tA.
Description:
Shape: Body subspherical.
Wall relationships: Endophragm appressed between processes.
Wall features: Parasutural features normally absent; a few examples with parasutural features are known. Intratabular processes generally open distally, commonly smooth with expanded, perforate, serrate to aculeate tips: periphragm between processes a smooth to faintly ornamented.
Paratabulation: Indicated by intratabular processes; gonyaulacacean, process formula: 4`, 6``, 0c, 5-6```, 1p, 1````, 0-3s.
Archeopyle: Apical, Type tA; principle archeopyle suture zigzag; operculum free.
Paracingulum: Position indicated by the absence of processes.
Parasulcus: Indicated by up to three processes, or by the absence of processes.
Size: Intermediate to large.
Affinities:
Oligosphaeridium differs from Hystrichosphaeridium and Perisseiasphaeridium in lacking paracingular processes, and from Areosphaeridium in having tubiform rather than solid processes.
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Emended description:
Davey, 1982:
Diagnosis:
Shape: The body is spherical to subspherical in shape with only minor dorso-ventral flattening.
Wall: the cyst wall is apparently two-layered, the layers being closely appressed except where the periphragm alone forms the processes. The surface is smooth to coarsely verrucate; an internal structuring maybe present. The processes are generally smooth.
Paratabulation: the parasutures are occasionally defined either by a positive (i.e. ridges) or a negative (i.e. lack of granulation) ornamentation. The paratabulation formula is 4`, 6`, 6c, 6```, 1p, 1````, 5s.
Processes: The plate-centered processes are basically of tubiform shape and flare distally to terminate with several spines. They vary in width according to position on the cyst with the pre-, postcingular and antapical processes being the largest. Rarely a solid process is present in the 1``` position and one may be present in the parasulcal region. The process formula is 4`, 6``, 5-6```, 1ps, 1p, 1```` plus0-1s.
Paracingular processes are absent; the only parasulcal process normally present is the posterior parasulcal.
Archaeopyle: an apical archaeopyle is normally developed by the detachment of the apical paraplates as a unit (Type A). It has a strongly zigzag margin with a deep parasulcal notch.
Affinities:
The genera Cymososphaeridium and Stiphrosphaeridium have similar process formulae but the processes are basically solid not tubiform. The process formula of the tubiform processes in Perisseiasphaeridium is the same as in Oligosphaeridium but fine, solid paracingular and parasulcal processes are also present.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Oligosphaeridium Davey and Williams, 1966b, emend. Davey, 1982b. Oligosphaeridium was emended by Davey (1982b, p.13) as follows (in part); Central body spherical to subspherical, smooth to coarsely verrucate, sometimes with parasutures occasionally defined by positive or negative ornamentation. Tabulation 4`, 6", 6c, 6``` , 1p, 1```` , 5s. Processes plate-centered, tubiform and flared distally, of variable width depending on plate location, and with sometimes a solid process on 1``` and a sulcal. Process formula 4`, 6", 5-6``` , 1ps, 1p, 1```` , plus 0-1s. The only sulcal process normally present is the ps. Archeopyle apical, type (A). Archeopyle margin strongly zig-zag with a deep sulcal notch.
[Oligosphaeridium, Davey and Williams, 1966b, p. 70-71; Emendation: Davey, 1982b, p.13
Type species: originally as Xanthidium tubiferum var. complex, White, 1842 (pl.4, fig.11) ; Neotype: Davey and Williams, 1966b (pl.7, fig.1), designated by Davey and Williams (1966b, p.71)]
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Original description: [Davey and Williams, 1966]:
Diagnosis:
Subspherical chorate cyst possessing a reflected tabulation of 4`, 6``, 5-6```, 1p, 1````. Processes tubiform, open distally, intratabular, one process per plate area. Number of processes never more than 18. Archaeopyle apical.
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Modified description:
Stover and Evitt 1978, p. 68-69:
Synopsis:
Cysts skolochorate, gonyaulacacean; body subspherical with 18 - 21 hollow cylindrical to tubiform intratabular processes that are generally open and normally expanded distally; cingular processes absent; archeopyle apical, Type tA.
Description:
Shape: Body subspherical.
Wall relationships: Endophragm appressed between processes.
Wall features: Parasutural features normally absent; a few examples with parasutural features are known. Intratabular processes generally open distally, commonly smooth with expanded, perforate, serrate to aculeate tips: periphragm between processes a smooth to faintly ornamented.
Paratabulation: Indicated by intratabular processes; gonyaulacacean, process formula: 4`, 6``, 0c, 5-6```, 1p, 1````, 0-3s.
Archeopyle: Apical, Type tA; principle archeopyle suture zigzag; operculum free.
Paracingulum: Position indicated by the absence of processes.
Parasulcus: Indicated by up to three processes, or by the absence of processes.
Size: Intermediate to large.
Affinities:
Oligosphaeridium differs from Hystrichosphaeridium and Perisseiasphaeridium in lacking paracingular processes, and from Areosphaeridium in having tubiform rather than solid processes.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Davey, 1982:
Diagnosis:
Shape: The body is spherical to subspherical in shape with only minor dorso-ventral flattening.
Wall: the cyst wall is apparently two-layered, the layers being closely appressed except where the periphragm alone forms the processes. The surface is smooth to coarsely verrucate; an internal structuring maybe present. The processes are generally smooth.
Paratabulation: the parasutures are occasionally defined either by a positive (i.e. ridges) or a negative (i.e. lack of granulation) ornamentation. The paratabulation formula is 4`, 6`, 6c, 6```, 1p, 1````, 5s.
Processes: The plate-centered processes are basically of tubiform shape and flare distally to terminate with several spines. They vary in width according to position on the cyst with the pre-, postcingular and antapical processes being the largest. Rarely a solid process is present in the 1``` position and one may be present in the parasulcal region. The process formula is 4`, 6``, 5-6```, 1ps, 1p, 1```` plus0-1s.
Paracingular processes are absent; the only parasulcal process normally present is the posterior parasulcal.
Archaeopyle: an apical archaeopyle is normally developed by the detachment of the apical paraplates as a unit (Type A). It has a strongly zigzag margin with a deep parasulcal notch.
Affinities:
The genera Cymososphaeridium and Stiphrosphaeridium have similar process formulae but the processes are basically solid not tubiform. The process formula of the tubiform processes in Perisseiasphaeridium is the same as in Oligosphaeridium but fine, solid paracingular and parasulcal processes are also present.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Oligosphaeridium Davey and Williams, 1966b, emend. Davey, 1982b. Oligosphaeridium was emended by Davey (1982b, p.13) as follows (in part); Central body spherical to subspherical, smooth to coarsely verrucate, sometimes with parasutures occasionally defined by positive or negative ornamentation. Tabulation 4`, 6", 6c, 6``` , 1p, 1```` , 5s. Processes plate-centered, tubiform and flared distally, of variable width depending on plate location, and with sometimes a solid process on 1``` and a sulcal. Process formula 4`, 6", 5-6``` , 1ps, 1p, 1```` , plus 0-1s. The only sulcal process normally present is the ps. Archeopyle apical, type (A). Archeopyle margin strongly zig-zag with a deep sulcal notch.