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Ambonosphaera
From Williams et al., 2017:
[Ambonosphaera, Fensome, 1979, p. 50-51; Emendation: Prauss, 1989, p. 31
Tax. jr. syn. of Polygonifera Habib, 1972, according to Brenner, 1988, Prauss, 1989, retained Ambonosphaera as a separate genus
Type species: Ambonosphaera calloviana, Fensome, 1979 (pl.7, figs.3,6,9; text-figs.16B–C)]
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Original description: [Fensome, 1979]:
Diagnosis:
A genus of dinoflagellate possessing a subspherical, subovoidal or subpolygonal cavate cyst on which there is no development of antapical or lateral horns, though weakly developed apical prominences may or may not occur.
A paratabulation is more or less well-developed on the periphragm. It is gonyaulacoid: 4`, 5-6``, 6-7c, 6-7```, 1p, 0-1pv, 1(-2?)````, ns. Paratabulation is usually weakly represented on, or absent from the relatively thicker walled endophragm.
The archaeopyle is formed by loss of the apical paraplate series (type 4A).
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Modified description:
Stover and Williams, 1987, p. 13-14:
Synopsis:
Cysts proximate, subspherical to polyhedral; paratabulation poorly expressed by parasutural folds, formula 4`, 5-6?``, 6c, 5```, 1p, 1````; sulcal paraplates not discernible; archaeopyle apical, type [4A], typically with deep parasulcal notch, operculum free.
Description:
Shape: Subspherical to subpolygonal.
Wall relationships: Endophragm and periphragm appressed except in parasutural areas and occasionally in apical and antapical regions.
Wall features: Low parasutural folds indicate paraplate boundaries; areas between parasutures variably granulate.
Archeopyle: Apical type [4A]; operculum free; archeopyle margin with conspicuous parasulcal notch.
Paratabulation: Details difficult to determine, most probably gonyaulacacean, formula: 4`, 5-6?``, 6c, 5```,1p, 1```` with the five postcingular paraplates apparently equivalent to plates 2```- 6```.
Paracingulum: Indicated by parallel, transverse folds; area between folds may be subdivided by indistinct longitudinal features.
Parasulcus: Indicated by bordering parasutural features; subdivision not discernible.
Size: Small, length about 40 µm to 50 µm.
Affinities:
Ambonosphaera differs from Lithodinia Eisenack 1935, emended Gocht 1975 in having two wall layers and a one piece operculum (a [4A] apical archeopyle) rather than an undifferentiated autophragm and a compound operculum composed of four opercular pieces (a 4A apical archeopyle). The distinction between Ambonosphaera and Meiourogonyaulax Sarjeant 1966 is not obvious, and it may be that the two are congeneric. It is difficult to confirm the paratabulation given in the generic diagnosis and shown in the line drawings of Fensome (1979, p. 50, figs. 16-17) and in the photomicrographs (Fensome, 1979, pl. 7, figs. 3, 5, 6, 8, 9), although the paratabulation appears to be gonyaulacacean. Accordingly, the formula given in the synopsis is modified slightly from that stated by Fensome. The presence of two antapical paraplates and 7 cingular paraplates and the shape of the hypocystal paraplate variously labelled as 6```, ?6```, or 6 or 7``` is not consistent with the gonyaulacacean pattern. It is not obvious that Ambonosphaera calloviana is cavate in the sense of a completely enclosing periphragm which is clearly separated from an underlying endophragm over a significant part of the cyst. Fensome 1979, p. 52 stated . . . "the two wall layers may be closely appressed over almost all of the cyst surface" ... This suggests that cavation is confined to relatively small areas beneath the parasutural features. If such is the case, we would be inclined to consider Ambonosphaera as a junior synonym of Meiourogonyaulax, Sarjeant 1966.
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Emended description:
Prauss, 1989: (Translation: Fensome et al., 1991, p. 29)
Diagnosis:
Cyst habit proximate/cavate to proximate/chrocavate.
Areation: XPR, 4`, 5``-6``, 6c-7c, 5```-6```, 0-1p, 1````, ns.
Archaeopyle: apical, probably 1`+2`+3`+4`; operculum foederate, secate (1`+2`+3`+4`)(s). Accessory archaeopyle sutures are distinct and strongly developed.
[Ambonosphaera, Fensome, 1979, p. 50-51; Emendation: Prauss, 1989, p. 31
Tax. jr. syn. of Polygonifera Habib, 1972, according to Brenner, 1988, Prauss, 1989, retained Ambonosphaera as a separate genus
Type species: Ambonosphaera calloviana, Fensome, 1979 (pl.7, figs.3,6,9; text-figs.16B–C)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Fensome, 1979]:
Diagnosis:
A genus of dinoflagellate possessing a subspherical, subovoidal or subpolygonal cavate cyst on which there is no development of antapical or lateral horns, though weakly developed apical prominences may or may not occur.
A paratabulation is more or less well-developed on the periphragm. It is gonyaulacoid: 4`, 5-6``, 6-7c, 6-7```, 1p, 0-1pv, 1(-2?)````, ns. Paratabulation is usually weakly represented on, or absent from the relatively thicker walled endophragm.
The archaeopyle is formed by loss of the apical paraplate series (type 4A).
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Modified description:
Stover and Williams, 1987, p. 13-14:
Synopsis:
Cysts proximate, subspherical to polyhedral; paratabulation poorly expressed by parasutural folds, formula 4`, 5-6?``, 6c, 5```, 1p, 1````; sulcal paraplates not discernible; archaeopyle apical, type [4A], typically with deep parasulcal notch, operculum free.
Description:
Shape: Subspherical to subpolygonal.
Wall relationships: Endophragm and periphragm appressed except in parasutural areas and occasionally in apical and antapical regions.
Wall features: Low parasutural folds indicate paraplate boundaries; areas between parasutures variably granulate.
Archeopyle: Apical type [4A]; operculum free; archeopyle margin with conspicuous parasulcal notch.
Paratabulation: Details difficult to determine, most probably gonyaulacacean, formula: 4`, 5-6?``, 6c, 5```,1p, 1```` with the five postcingular paraplates apparently equivalent to plates 2```- 6```.
Paracingulum: Indicated by parallel, transverse folds; area between folds may be subdivided by indistinct longitudinal features.
Parasulcus: Indicated by bordering parasutural features; subdivision not discernible.
Size: Small, length about 40 µm to 50 µm.
Affinities:
Ambonosphaera differs from Lithodinia Eisenack 1935, emended Gocht 1975 in having two wall layers and a one piece operculum (a [4A] apical archeopyle) rather than an undifferentiated autophragm and a compound operculum composed of four opercular pieces (a 4A apical archeopyle). The distinction between Ambonosphaera and Meiourogonyaulax Sarjeant 1966 is not obvious, and it may be that the two are congeneric. It is difficult to confirm the paratabulation given in the generic diagnosis and shown in the line drawings of Fensome (1979, p. 50, figs. 16-17) and in the photomicrographs (Fensome, 1979, pl. 7, figs. 3, 5, 6, 8, 9), although the paratabulation appears to be gonyaulacacean. Accordingly, the formula given in the synopsis is modified slightly from that stated by Fensome. The presence of two antapical paraplates and 7 cingular paraplates and the shape of the hypocystal paraplate variously labelled as 6```, ?6```, or 6 or 7``` is not consistent with the gonyaulacacean pattern. It is not obvious that Ambonosphaera calloviana is cavate in the sense of a completely enclosing periphragm which is clearly separated from an underlying endophragm over a significant part of the cyst. Fensome 1979, p. 52 stated . . . "the two wall layers may be closely appressed over almost all of the cyst surface" ... This suggests that cavation is confined to relatively small areas beneath the parasutural features. If such is the case, we would be inclined to consider Ambonosphaera as a junior synonym of Meiourogonyaulax, Sarjeant 1966.
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Emended description:
Prauss, 1989: (Translation: Fensome et al., 1991, p. 29)
Diagnosis:
Cyst habit proximate/cavate to proximate/chrocavate.
Areation: XPR, 4`, 5``-6``, 6c-7c, 5```-6```, 0-1p, 1````, ns.
Archaeopyle: apical, probably 1`+2`+3`+4`; operculum foederate, secate (1`+2`+3`+4`)(s). Accessory archaeopyle sutures are distinct and strongly developed.