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Diconodinium
From Fensome et al., 2019:
Diconodinium, Eisenack and Cookson, 1960, p.3.
Emendation: Morgan, 1977, p.125.
Type: Deflandre and Cookson, 1955, pl.1, fig.5, as Palaeohystrichophora multispina.
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Original description: [Eisenack and Cookson, 1960]:
Description:
Shell fusiform to almost spherical, without tabulation and capsule, divided equally or unequally by a circular girdle; ventral surface with or without clear lines which run longitudinally from the end of the girdle to or towards both apex and antapex, delimiting an area which corresponds in position to a longitudinal furrow. Epitheca terminated by a strongly marked to inconspicuous process with a bifid or concave tip; hypotheca with a prominent to much reduced spinelike projection. Shell membrane thin, smooth or ornamented with granules, spinules or small spines.
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Emended descriptions:
Morgan, 1977:
Shape:
Ambitus rhomboidal to fusiform, prolonged into a truncate apical horn, and a single, sharply pointed antapical horn located close to the midline. Slight bulge close to antapical horn may suggest location of second undeveloped antapical horn. Autocyst widest at the paracingular area in ambital view. Epicyst and hypocyst of approximately equal size or hypocyst slightly larger. Compression dorsal-ventral.
Phragma: Generally thin apparent autophragm, may thicken at apex and antapex to form solid or partly solid horns. Surface psilate, granulate, spinulate or bearing ridges. Ornamentation weakly tabular or nontabular. (Rare specimens have an ovoidal psilate endophragm with a fusiform to rhomboidal ornamented periphragm, and pericoels beneath the horns.)
Paratabulation: Often nontabular, rare specimens may have indications of pandasutural zones with intratabular granules, or have longer or more dense parasutural spines, or have parasutural ridges. Paratabulation, when discernible, is peridinioid--4`, 3a, 7", ?5```, 2````. Paraplates 1`, 2` and 4` are elongate, 3` is short and broad. Standard hexa 2a paraplate, narrower than 4"; 1a and 3a paraplates smaller, five-sided. Paracingulum may not be discernible but it is usually marked by parallel slightly raised parasutures bearing granules, ridges or spines. Individual paraplates not visible. Parasulcus rarely discernible, outlined by slightly raised parasutures, or as less dense area of ornamentation. Individual paraplates not visible.
Archeopyle: Rarely discernible, 1a (2a only) or 1Pa (2a + 4").
Dimensions: 50-73 µm long and 30-53 µm broad.
Affinities:
Diconodinium is characterized by a rhombical to fusiform ambitus, with a truncate apical horn and a single sharp antapical horn located lose to the midline, generally nontabular psilate to spinulate autophragm and a normal hexa Ia (IP)a archaeopyle.
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Modified descriptions:
Stover and Evitt, 1978, p. 101:
Synopsis:
Cysts proximate to proximochorate, generally acavate, usually biconical, with single apical and antapical horns; autophragm smooth or variously ornamented, ornamentation generally nontabular, occasionally intratabular; paratabulation peridiniacean (when discernible), commonly
indicated by paracingulum only, less frequently by paracingulum and archeopyle, and rarely by parasutural features; archeopyle intercalary,
Type la or combination, Type (IP)a.
Description:
Shape: Usually biconical; less commonly rounded, with single apical and antapical horns; antapical horn close to longitudinal axis.
Wall relationships: Generally autophragm only; some species may show indications of cavation.
Wall features: Parasutural features rare; autophragm typically ornamented with nontabular granules, cones, or spines.
Paratabulation: Indicated by paracingulum only or by paracingulum and archeopyle, rarely by pandasuturate bands between intratabular clusters of ornamentation.
Archeopyle: Intercalary, Type la (2a only), or combination, Type (IP)a; archeopyle rarely discernible.
Paracingulum: Generally indicated by parallel transverse equatorial ridges bearing granules, cones, or spines.
Parasulcus: Rarely discernible; may be indicated by an area with less dense ornamentation or delimited by faint low ridges.
Size: Intermediate.
Affinities:
Diconodinium differs from Kalyptea in that its archeopyle has an attached rather than a free operculum. It has, as well, indications of a paracingulum, which Kalyptea lacks. Most species of Diconodinium are more strongly ornamented than those of Kalyptea.
Diconodinium, Eisenack and Cookson, 1960, p.3.
Emendation: Morgan, 1977, p.125.
Type: Deflandre and Cookson, 1955, pl.1, fig.5, as Palaeohystrichophora multispina.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Eisenack and Cookson, 1960]:
Description:
Shell fusiform to almost spherical, without tabulation and capsule, divided equally or unequally by a circular girdle; ventral surface with or without clear lines which run longitudinally from the end of the girdle to or towards both apex and antapex, delimiting an area which corresponds in position to a longitudinal furrow. Epitheca terminated by a strongly marked to inconspicuous process with a bifid or concave tip; hypotheca with a prominent to much reduced spinelike projection. Shell membrane thin, smooth or ornamented with granules, spinules or small spines.
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Emended descriptions:
Morgan, 1977:
Shape:
Ambitus rhomboidal to fusiform, prolonged into a truncate apical horn, and a single, sharply pointed antapical horn located close to the midline. Slight bulge close to antapical horn may suggest location of second undeveloped antapical horn. Autocyst widest at the paracingular area in ambital view. Epicyst and hypocyst of approximately equal size or hypocyst slightly larger. Compression dorsal-ventral.
Phragma: Generally thin apparent autophragm, may thicken at apex and antapex to form solid or partly solid horns. Surface psilate, granulate, spinulate or bearing ridges. Ornamentation weakly tabular or nontabular. (Rare specimens have an ovoidal psilate endophragm with a fusiform to rhomboidal ornamented periphragm, and pericoels beneath the horns.)
Paratabulation: Often nontabular, rare specimens may have indications of pandasutural zones with intratabular granules, or have longer or more dense parasutural spines, or have parasutural ridges. Paratabulation, when discernible, is peridinioid--4`, 3a, 7", ?5```, 2````. Paraplates 1`, 2` and 4` are elongate, 3` is short and broad. Standard hexa 2a paraplate, narrower than 4"; 1a and 3a paraplates smaller, five-sided. Paracingulum may not be discernible but it is usually marked by parallel slightly raised parasutures bearing granules, ridges or spines. Individual paraplates not visible. Parasulcus rarely discernible, outlined by slightly raised parasutures, or as less dense area of ornamentation. Individual paraplates not visible.
Archeopyle: Rarely discernible, 1a (2a only) or 1Pa (2a + 4").
Dimensions: 50-73 µm long and 30-53 µm broad.
Affinities:
Diconodinium is characterized by a rhombical to fusiform ambitus, with a truncate apical horn and a single sharp antapical horn located lose to the midline, generally nontabular psilate to spinulate autophragm and a normal hexa Ia (IP)a archaeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified descriptions:
Stover and Evitt, 1978, p. 101:
Synopsis:
Cysts proximate to proximochorate, generally acavate, usually biconical, with single apical and antapical horns; autophragm smooth or variously ornamented, ornamentation generally nontabular, occasionally intratabular; paratabulation peridiniacean (when discernible), commonly
indicated by paracingulum only, less frequently by paracingulum and archeopyle, and rarely by parasutural features; archeopyle intercalary,
Type la or combination, Type (IP)a.
Description:
Shape: Usually biconical; less commonly rounded, with single apical and antapical horns; antapical horn close to longitudinal axis.
Wall relationships: Generally autophragm only; some species may show indications of cavation.
Wall features: Parasutural features rare; autophragm typically ornamented with nontabular granules, cones, or spines.
Paratabulation: Indicated by paracingulum only or by paracingulum and archeopyle, rarely by pandasuturate bands between intratabular clusters of ornamentation.
Archeopyle: Intercalary, Type la (2a only), or combination, Type (IP)a; archeopyle rarely discernible.
Paracingulum: Generally indicated by parallel transverse equatorial ridges bearing granules, cones, or spines.
Parasulcus: Rarely discernible; may be indicated by an area with less dense ornamentation or delimited by faint low ridges.
Size: Intermediate.
Affinities:
Diconodinium differs from Kalyptea in that its archeopyle has an attached rather than a free operculum. It has, as well, indications of a paracingulum, which Kalyptea lacks. Most species of Diconodinium are more strongly ornamented than those of Kalyptea.