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Spongodinium
From Williams et al., 2017:
[Spongodinium, Deflandre, 1936b, p. 169-170; Emendations: Stover and Evitt, 1978, p. 191-192; Lucas-Clark, 1987, p. 166.
Type species: Spongodinium delitiense, (Ehrenberg, 1838); Deflandre, 1936; emend. Lucas-Clark, 1987
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Original description: [Deflandre, 1936]: (Translation: Stover and Evitt, 1978, p. 191):
Description:
The theca is ellipsoidal, ovoid or subspherical in shape, and carries a strong, short asymmetrically placed horn at one pole. The whole tegument is alveolate and divided into unequal and irregular fields by fine membranes perpendicular to its surface, membranes which thicken at their points of junction, forming there a kind of apparently robust pillar. Around the equator a series of alveoli are better developed and show a higher membrane, bent and in places closed by junctions with that which faces it. It thus forms a kind of girdle, sometimes difficult to see but constant.
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Emended descriptions:
Stover and Evitt, 1978:
Synopsis:
Cysts proximate, subspherical to subpolyhedral with prominent apical horn; autophragm only, in part vesicular; vesicle distribution indicates paracingulum and other traces of paratabulation; archeopyle precingular, Type P; operculum free.
Modified description:
Shape: Subspherical to subpolyhedral with prominent apical horn and, usually, two broadly rounded antapical prominences.
Wall relationships: Autophragm only, unevenly vesicular; separated periphragm and endophragm simulated in highly vesiculate areas such as paracingulum and apical horn.
Wall features: Parasutures incompletely indicated by narrow strips, along which the wall may be thicker and more vesiculate than elsewhere; vesicular structure concentrated along paracingulum and at bases of horns.
Paratabulation: Incompletely indicated by archeopyle, paracingulum, and distribution of vesicular areas. Probably gonyaulacacean; formula unknown.
Archeopyle: Precingular, Type P (presumably 3`` only); large and rounded, evidently enlarged; operculum free.
Paracingulum: Indicated by an equatorial bulge in coarsely vesicular wall.
Parasulcus: Indicated by interruption in paracingulum and partly outlined by vesicular wall.
Size: Large.
Affinities:
The vesicular autophragm is unique. Genus Spongodinium Deflandre 1936.
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Lucas-Clark, 1987:
Description:
Large acavate, subspherical to subpolyhedral cysts, circular in equatorial section, with prominent apical horn. Cyst basically an autophragm with vesiculate structure. An outer wall (which could be considered periphragm or ectophragm) is simulated in highly vesicular areas by a thin membrane enclosing the vesicles. Amount of vesiculation variable. Vesicles most numerous around cingulum, where they form a broad-based flange, around the apical horn, and on the antapical paraplate. Some specimens completely covered by vesicles.
Archeopyle precingular, type P(4), operculum enlarged along cingular and precingular margins, rounded, free.
Paratabulation usually incompletely expressed and obscured by vesiculation, but sometimes indicated by parasutural ridges, alignment of vesicles along parasutures, or confinement of vesicles to intratabular areas. Growth bands variably expressed by accessory ridges and variations in vesiculation.
Paratabulation gonyaulacoid and similar to that of Cribroperidinium. The following paraplates can be demonstrated in some specimens: One preapical (P), four apicals ( I u, B, C, A), six precingulars ( 1 i, 2-6), four sulcals (ai, Ii, Im, Z), one posterior intercalary (X), six postcingulars (Iu, II-VI), and one antapical (Y). Ventral organization: elongated A and lu both contact pentagonal li; ends of cingulum offset slightly. Apical organization: A, B, and lu contact P; C does not contact P; A appears to contact B; Q probably not present. Posterior sulcal organization: elongate X, crescent-shaped Z; small Ii, Im, and Iu. Dorsal organization: IV/V parasuture offset in position to the left of 4/5. Hypocystal organization: sexiform, Y asymmetrical with V/Y parasuture longer than III/Y parasuture. Y usually has an angular contact with V, expressing contact with trace of wide growth band. Y is rotated so that the IV/V/Y triple junction is approximately middorsal.
Affinities: (p. 167):
The emendation here differs from previous descriptions primarily in recognizing the detailed paratabulation pattern. Although indications of paratabulation are typically obscured by the complexity of the vesicular wall, in specimens of S. delitiense from the Bearpaw Formation of Montana, the sparseness of the vesicles in the wall and their alignment along parasutures allowed observation of part of the paratabulation. Other specimens (provided by J. Lentin) from an Arctic Ocean core permitted observation of the parasutures after the vesicles had burst or collapsed from drying and exposure to the vacuum of the SEM. The combination of the Bearpaw and Arctic Ocean specimens allowed documentation of a nearly complete paratabulation pattern for Spongodinium, except that contacts in the preapical region are still uncertain.
[Spongodinium, Deflandre, 1936b, p. 169-170; Emendations: Stover and Evitt, 1978, p. 191-192; Lucas-Clark, 1987, p. 166.
Type species: Spongodinium delitiense, (Ehrenberg, 1838); Deflandre, 1936; emend. Lucas-Clark, 1987
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Deflandre, 1936]: (Translation: Stover and Evitt, 1978, p. 191):
Description:
The theca is ellipsoidal, ovoid or subspherical in shape, and carries a strong, short asymmetrically placed horn at one pole. The whole tegument is alveolate and divided into unequal and irregular fields by fine membranes perpendicular to its surface, membranes which thicken at their points of junction, forming there a kind of apparently robust pillar. Around the equator a series of alveoli are better developed and show a higher membrane, bent and in places closed by junctions with that which faces it. It thus forms a kind of girdle, sometimes difficult to see but constant.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Stover and Evitt, 1978:
Synopsis:
Cysts proximate, subspherical to subpolyhedral with prominent apical horn; autophragm only, in part vesicular; vesicle distribution indicates paracingulum and other traces of paratabulation; archeopyle precingular, Type P; operculum free.
Modified description:
Shape: Subspherical to subpolyhedral with prominent apical horn and, usually, two broadly rounded antapical prominences.
Wall relationships: Autophragm only, unevenly vesicular; separated periphragm and endophragm simulated in highly vesiculate areas such as paracingulum and apical horn.
Wall features: Parasutures incompletely indicated by narrow strips, along which the wall may be thicker and more vesiculate than elsewhere; vesicular structure concentrated along paracingulum and at bases of horns.
Paratabulation: Incompletely indicated by archeopyle, paracingulum, and distribution of vesicular areas. Probably gonyaulacacean; formula unknown.
Archeopyle: Precingular, Type P (presumably 3`` only); large and rounded, evidently enlarged; operculum free.
Paracingulum: Indicated by an equatorial bulge in coarsely vesicular wall.
Parasulcus: Indicated by interruption in paracingulum and partly outlined by vesicular wall.
Size: Large.
Affinities:
The vesicular autophragm is unique. Genus Spongodinium Deflandre 1936.
-------------------------------------------
Lucas-Clark, 1987:
Description:
Large acavate, subspherical to subpolyhedral cysts, circular in equatorial section, with prominent apical horn. Cyst basically an autophragm with vesiculate structure. An outer wall (which could be considered periphragm or ectophragm) is simulated in highly vesicular areas by a thin membrane enclosing the vesicles. Amount of vesiculation variable. Vesicles most numerous around cingulum, where they form a broad-based flange, around the apical horn, and on the antapical paraplate. Some specimens completely covered by vesicles.
Archeopyle precingular, type P(4), operculum enlarged along cingular and precingular margins, rounded, free.
Paratabulation usually incompletely expressed and obscured by vesiculation, but sometimes indicated by parasutural ridges, alignment of vesicles along parasutures, or confinement of vesicles to intratabular areas. Growth bands variably expressed by accessory ridges and variations in vesiculation.
Paratabulation gonyaulacoid and similar to that of Cribroperidinium. The following paraplates can be demonstrated in some specimens: One preapical (P), four apicals ( I u, B, C, A), six precingulars ( 1 i, 2-6), four sulcals (ai, Ii, Im, Z), one posterior intercalary (X), six postcingulars (Iu, II-VI), and one antapical (Y). Ventral organization: elongated A and lu both contact pentagonal li; ends of cingulum offset slightly. Apical organization: A, B, and lu contact P; C does not contact P; A appears to contact B; Q probably not present. Posterior sulcal organization: elongate X, crescent-shaped Z; small Ii, Im, and Iu. Dorsal organization: IV/V parasuture offset in position to the left of 4/5. Hypocystal organization: sexiform, Y asymmetrical with V/Y parasuture longer than III/Y parasuture. Y usually has an angular contact with V, expressing contact with trace of wide growth band. Y is rotated so that the IV/V/Y triple junction is approximately middorsal.
Affinities: (p. 167):
The emendation here differs from previous descriptions primarily in recognizing the detailed paratabulation pattern. Although indications of paratabulation are typically obscured by the complexity of the vesicular wall, in specimens of S. delitiense from the Bearpaw Formation of Montana, the sparseness of the vesicles in the wall and their alignment along parasutures allowed observation of part of the paratabulation. Other specimens (provided by J. Lentin) from an Arctic Ocean core permitted observation of the parasutures after the vesicles had burst or collapsed from drying and exposure to the vacuum of the SEM. The combination of the Bearpaw and Arctic Ocean specimens allowed documentation of a nearly complete paratabulation pattern for Spongodinium, except that contacts in the preapical region are still uncertain.