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Surculosphaeridium
From Fensome et al., 2019:
Surculosphaeridium, Davey et al., 1966, p.160โ161.
Emendations: Davey, 1982b, p.15 -- however, see Stancliffe and Sarjeant (1990, p.207); Fensome et al., 2016b, p.70.
Taxonomic senior synonym: Polystephanosphaera, by implication in Courtinat (1989, p.173), who considered the "type species", Polystephanosphaera valensii, to be a taxonomic junior synonym of Hystrichosphaeridium (as and now Surculosphaeridium) vestitum --however, Stancliffe and Sarjeant (1990, p.207โ208) retained the two species, aswell as the genus Surculosphaeridium.
Type: Sarjeant, 1960a, pl.6, fig.2, as Hystrichosphaeridium cribrotubiferum.
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Original description: [Davey et al. 1966]:
Diagnosis:
Subspherical chorate cysts bearing a moderate number of intratabular processes, considered to reflect the tabulation 4`, 6``, 6c` 6```, 1p, 3````. Processes solid, closed distally and branched. Archaeopyle apical.
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Modified description:
Stover and Evitt 1978, p. 83.
Synopsis:
Cysts skolochorate, body subspherical with approximately 25 solid, isolated, distally branched, intratabular processes; paratabulation gonyaulacacean, indicated by intratabular processes; archaeopyle apical, Type (tA).
Description:
Shape: Body subspherical.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Intratabular processes relatively slender, solid, branched distally, and may be perforate; autophragm smooth.
Paratabulation: Indicated by intratabular processes, gonyaulacacean; process formula: 4`, 6``, 6c, 6```, 1p, 1````, 1s. Presence of three antapical processes unusual and requires confirmation.
Archaeopyle: apical, probably Type tA. Operculum free; exact shape of operculum and trace of principal archaeopyle suture unknown.
Paracingulum: Indicated by six intratabular processes.
Parasulcus: Position suggested by a few slender processes in midventral part of hypocyst.
Size: Intermediate to large.
Affinities:
Surculosphaeridium differs from Hystrichosphaeridium in having solid rather than tubular processes. It differs from areosphaeridium, which also has solid intratabular processes, in not having fenestrate, arcuate, or platformlike features at the ends of the processes.
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Emended description:
Davey, 1982, p. 15:
Diagnosis:
Shape: The body is sphaerical to subsphaerical in shape with only minor dorsal-ventral flattering.
Wall: The cyst wall is apparently two-layered, the two layers being closely appressed except where the periphragm alone forms the processes. The surface is smooth to lightly ornamented and the processes are generally smooth.
Paratabulation: Parasutures not observed.
Processes: The processes are solid, often with internal vacuoles, and simply to complexly branched. The apical, pre-, postcingular, parasutural and antapical processes are plate-centered. Although the paracingular processes are usually deeply bifurcate and also plate-centered, sometimes, the bifurcation extends to the cyst wall so forming two processes per cingular paraplate. The processes vary in width according to position on cyst with the pre-, postcingular and antapical being the largest. The process formula is 4`, 6``, 6c, 6```, 1p, 1````, 1-5s.
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.
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Fensome et al., 2016b:
Emended diagnosis. Chorate gonyaulacacean cysts with spheroidal central bodies. Acavate. Processes are solid and branched and/or distally furcate. There may be one to four processes per plate, sometimes forming complexes in cases where there is more than one process per plate. Archaeopyle apical, with the formula A (1โ4ยด); operculum free.
Remarks. Surculosphaeridium is emended to allow inclusion of forms with more than one process per plate. However, there must be processes or process complexes on all the plates, including the precingulars.
Surculosphaeridium, Davey et al., 1966, p.160โ161.
Emendations: Davey, 1982b, p.15 -- however, see Stancliffe and Sarjeant (1990, p.207); Fensome et al., 2016b, p.70.
Taxonomic senior synonym: Polystephanosphaera, by implication in Courtinat (1989, p.173), who considered the "type species", Polystephanosphaera valensii, to be a taxonomic junior synonym of Hystrichosphaeridium (as and now Surculosphaeridium) vestitum --however, Stancliffe and Sarjeant (1990, p.207โ208) retained the two species, aswell as the genus Surculosphaeridium.
Type: Sarjeant, 1960a, pl.6, fig.2, as Hystrichosphaeridium cribrotubiferum.
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Davey et al. 1966]:
Diagnosis:
Subspherical chorate cysts bearing a moderate number of intratabular processes, considered to reflect the tabulation 4`, 6``, 6c` 6```, 1p, 3````. Processes solid, closed distally and branched. Archaeopyle apical.
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Modified description:
Stover and Evitt 1978, p. 83.
Synopsis:
Cysts skolochorate, body subspherical with approximately 25 solid, isolated, distally branched, intratabular processes; paratabulation gonyaulacacean, indicated by intratabular processes; archaeopyle apical, Type (tA).
Description:
Shape: Body subspherical.
Wall relationships: Autophragm only.
Wall features: No parasutural features. Intratabular processes relatively slender, solid, branched distally, and may be perforate; autophragm smooth.
Paratabulation: Indicated by intratabular processes, gonyaulacacean; process formula: 4`, 6``, 6c, 6```, 1p, 1````, 1s. Presence of three antapical processes unusual and requires confirmation.
Archaeopyle: apical, probably Type tA. Operculum free; exact shape of operculum and trace of principal archaeopyle suture unknown.
Paracingulum: Indicated by six intratabular processes.
Parasulcus: Position suggested by a few slender processes in midventral part of hypocyst.
Size: Intermediate to large.
Affinities:
Surculosphaeridium differs from Hystrichosphaeridium in having solid rather than tubular processes. It differs from areosphaeridium, which also has solid intratabular processes, in not having fenestrate, arcuate, or platformlike features at the ends of the processes.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Davey, 1982, p. 15:
Diagnosis:
Shape: The body is sphaerical to subsphaerical in shape with only minor dorsal-ventral flattering.
Wall: The cyst wall is apparently two-layered, the two layers being closely appressed except where the periphragm alone forms the processes. The surface is smooth to lightly ornamented and the processes are generally smooth.
Paratabulation: Parasutures not observed.
Processes: The processes are solid, often with internal vacuoles, and simply to complexly branched. The apical, pre-, postcingular, parasutural and antapical processes are plate-centered. Although the paracingular processes are usually deeply bifurcate and also plate-centered, sometimes, the bifurcation extends to the cyst wall so forming two processes per cingular paraplate. The processes vary in width according to position on cyst with the pre-, postcingular and antapical being the largest. The process formula is 4`, 6``, 6c, 6```, 1p, 1````, 1-5s.
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.
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Fensome et al., 2016b:
Emended diagnosis. Chorate gonyaulacacean cysts with spheroidal central bodies. Acavate. Processes are solid and branched and/or distally furcate. There may be one to four processes per plate, sometimes forming complexes in cases where there is more than one process per plate. Archaeopyle apical, with the formula A (1โ4ยด); operculum free.
Remarks. Surculosphaeridium is emended to allow inclusion of forms with more than one process per plate. However, there must be processes or process complexes on all the plates, including the precingulars.