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Subtilisphaera
From Fensome et al., 2019:
Subtilisphaera, Jain and Millepied, 1973, p.26–27.
Emendations: Lentin and Williams, 1976, p.117–119; Santos et al., 2018, p.168.
Type: Jain and Millepied, 1973, pl.3, fig.31, as Subtilisphaera senegalensis.
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Original description: [Jain and Millepied 1973]:
Diagnosis:
Shell pentagonal-ovoid, test cavate to bicavate non-tabulate, asymmetrical; cingulum (girdle) well developed, dividing the shell into almost equal halves. Epitract broadly rounded with pointed to broadly obtuse apical horn; hypotract rounded having one prominent antapical horn and second undeveloped or only as a slight projection placed away from median axis (non-axial). Periphragm smooth to granulate, thin, delicate; capsule circular, filling periphragm completely or leaving a small pericoel. Archaeopyle mostly not seen, if present intercalary.
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Modified description:
Stover and Evitt 1978, p. 238-239:
Synopsis:
Cysts proximate, cavate, compressed subspherical to roundly peridinioid, with or without a short apical horn and with one or two short antapical horns or protrusions.
Description:
Shape: Compressed subspherical to roundly peridinoid, with or without a short apical horn and with one or two short antapical horns or protrusions.
Wall relationships: cysts circumcavate or bicavate; endocyst outline circular to elliptical.
Wall features: No parasutural features. Endophragm and periphragm smooth or faintly ornamented.
Paratabulation: Not indicated, or indicated by paracingulum only.
Archaeopyle: typically not discernible; presumably intercalary.
Paracingulum: Indicated by low transverse equatorial folds or ridges or by equatorial indentations on the lateral margins, or not indicated.
Parasulcus: Generally not indicated.
Size: Small to intermediate.
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Poulsen 1996, p. 85-86:
Remarks:
Durr (1988) preferred to retain S. inaffecta and S. paeminosa in Geiselodinium. However, the archeopyle split is seen, although only very rarely, and the apical horn in both of the species is, in my opinion, more than an apical peak. For this reason both species are here regarded as species of Subtilisphaera. Lentin and Williams (1993) also retained them as provisionally accepted species of Subtilisphaera.
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Emended description Santos et al., 2019:
Emended diagnosis: Cysts are proximate, peridinioid in shape, bicavate, cornucavate or circumcavate and nontabulate, except for the cingulum. Apical horn may be present or absent, and one non-axial antapical horn or two short non-axial antapical horns or protrusions may be present and may be symmetrical or asymmetrical. Endophragm is well developed, thin, smooth, scabrate or granulate. Periphragm is thin, smooth, scabrate, granulate or with elements of low relief such as thin, hair-like appendages. Archaeopyle is not discernible.
Remarks: Some authors have proposed the possibility that the type of archaeopyle is a transapical suture (i.e AIP) or intercalary (Lentin & Williams 1976; Stover & Evitt 1978), but the archeopyle is usually not observable. The original generic diagnosis of Jain & Millepied (1973) is emended here to allow the inclusion of forms having thin hair-like appendages. Subtilisphaera differs from Palaeohystrichophora by having an antapex with one or two non-axial horns.
Mahmoud (1998) and Fensome et al. (2009) used the presence of the hair-like appendages as a diagnostic feature at the generic level to distinguish these genera. However, we consider this feature to be better used at the specific level. At the generic level, we consider the overall outline (indicating a peridiniacean affinity by the non-axial antapical horns) to be more appropriate. According to the amendment proposed here, the genus Subtilisphaera (Jain & Millepied 1973) has one or two non-axial antapical horns. However, this difference from Palaeohystrichophora (with one axial horn) is not discernable in some specimens, and in that case we suggest that the specimens be assigned to a ‘Palaeohystrichophora/Subtilisphaera group’.
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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.
Subtilisphaera Jain and Millepied, 1973, emend. Lentin and Williams, 1976. This peridinioid cyst, according to Bujak and Davies (1983, p. 62) can have a transverse archeopyle suture between the apical and intercalary series (2`/1a, 3`/1a, 3`/2a, 3`/3a, 4`/3a), with incomplete or complete archeopyle sutures between the individual intercalary plates.
Subtilisphaera, Jain and Millepied, 1973, p.26–27.
Emendations: Lentin and Williams, 1976, p.117–119; Santos et al., 2018, p.168.
Type: Jain and Millepied, 1973, pl.3, fig.31, as Subtilisphaera senegalensis.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Jain and Millepied 1973]:
Diagnosis:
Shell pentagonal-ovoid, test cavate to bicavate non-tabulate, asymmetrical; cingulum (girdle) well developed, dividing the shell into almost equal halves. Epitract broadly rounded with pointed to broadly obtuse apical horn; hypotract rounded having one prominent antapical horn and second undeveloped or only as a slight projection placed away from median axis (non-axial). Periphragm smooth to granulate, thin, delicate; capsule circular, filling periphragm completely or leaving a small pericoel. Archaeopyle mostly not seen, if present intercalary.
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Modified description:
Stover and Evitt 1978, p. 238-239:
Synopsis:
Cysts proximate, cavate, compressed subspherical to roundly peridinioid, with or without a short apical horn and with one or two short antapical horns or protrusions.
Description:
Shape: Compressed subspherical to roundly peridinoid, with or without a short apical horn and with one or two short antapical horns or protrusions.
Wall relationships: cysts circumcavate or bicavate; endocyst outline circular to elliptical.
Wall features: No parasutural features. Endophragm and periphragm smooth or faintly ornamented.
Paratabulation: Not indicated, or indicated by paracingulum only.
Archaeopyle: typically not discernible; presumably intercalary.
Paracingulum: Indicated by low transverse equatorial folds or ridges or by equatorial indentations on the lateral margins, or not indicated.
Parasulcus: Generally not indicated.
Size: Small to intermediate.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Poulsen 1996, p. 85-86:
Remarks:
Durr (1988) preferred to retain S. inaffecta and S. paeminosa in Geiselodinium. However, the archeopyle split is seen, although only very rarely, and the apical horn in both of the species is, in my opinion, more than an apical peak. For this reason both species are here regarded as species of Subtilisphaera. Lentin and Williams (1993) also retained them as provisionally accepted species of Subtilisphaera.
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Emended description Santos et al., 2019:
Emended diagnosis: Cysts are proximate, peridinioid in shape, bicavate, cornucavate or circumcavate and nontabulate, except for the cingulum. Apical horn may be present or absent, and one non-axial antapical horn or two short non-axial antapical horns or protrusions may be present and may be symmetrical or asymmetrical. Endophragm is well developed, thin, smooth, scabrate or granulate. Periphragm is thin, smooth, scabrate, granulate or with elements of low relief such as thin, hair-like appendages. Archaeopyle is not discernible.
Remarks: Some authors have proposed the possibility that the type of archaeopyle is a transapical suture (i.e AIP) or intercalary (Lentin & Williams 1976; Stover & Evitt 1978), but the archeopyle is usually not observable. The original generic diagnosis of Jain & Millepied (1973) is emended here to allow the inclusion of forms having thin hair-like appendages. Subtilisphaera differs from Palaeohystrichophora by having an antapex with one or two non-axial horns.
Mahmoud (1998) and Fensome et al. (2009) used the presence of the hair-like appendages as a diagnostic feature at the generic level to distinguish these genera. However, we consider this feature to be better used at the specific level. At the generic level, we consider the overall outline (indicating a peridiniacean affinity by the non-axial antapical horns) to be more appropriate. According to the amendment proposed here, the genus Subtilisphaera (Jain & Millepied 1973) has one or two non-axial antapical horns. However, this difference from Palaeohystrichophora (with one axial horn) is not discernable in some specimens, and in that case we suggest that the specimens be assigned to a ‘Palaeohystrichophora/Subtilisphaera group’.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Subtilisphaera Jain and Millepied, 1973, emend. Lentin and Williams, 1976. This peridinioid cyst, according to Bujak and Davies (1983, p. 62) can have a transverse archeopyle suture between the apical and intercalary series (2`/1a, 3`/1a, 3`/2a, 3`/3a, 4`/3a), with incomplete or complete archeopyle sutures between the individual intercalary plates.