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Krutzschidinium
From Fensome et al., 2019:
"Krutzschidinium", Strauss, 1991a, p.52,54. Name not validly published: no validly published species.
Type: Strauss, 1991a, pl.1, figs.a–b; text-fig.4c, as Krutzschidinium spinosum.
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Original description: [Strauss, 1991]:
Diagnosis:
Cornucavate to slightly circumcavate cysts with a characteristically rounded pentagonal outline and a considerable dorsoventral compression.
One apical and two antapical distinct horns are located symmetrically to the longitudinal cyst-axis. They are triangular in shape with some spines giving them a more irregular branched appearance. Periphragm and endophragm are very delicate and pale and nearly always in close contact with one another except at the horn bases. Short, bulbose, spine-like processes arise from the periphragm and seem to be distributed in a parasutural pattern.
Cingulum and sulcus are broad, displaying almost no indentation, they may be bordered by parasutural rows of processes.
If decipherable, tabulation pattern is typically peridinoid: 4`, 3a, 7``, Xc, 5```, 2````, Xs, but often very incompletely developed.
Archaeopyle of variable type: the most common one is the 3I (1a-3a) - type, but archaeopyle formation rarely varies to include apicals (?tAtI) or to be a simple I (2a)-type.
Remarks:
The basic dorsal tabulation style seems to be a penta-style (compare Figs 3E, 3F and 3G with the figures on the plates), but outline of archaeopyle and run of other dorsal parasutures indicated by spiny crests also suggests the presence of quadra (and hexa?) style. Further observations are necessary to elucidate the real conditions.
Affinities:
The presence of variable archaeopyle type and parasutural arrangement of process-bearing crests makes Krutzschidinium most closely to the Phthanoperidinium - complex sensu Evitt (1985).
Significant differences between those two genera are the doubtless presence of a penta dorsal tabulation style in Krutzschidinium, the predominance of 3I-archaeopyle type (this type is not included in the emended diagnosis of Phthanoperidinium by Islam, 1982, although it is present, for instance, in P. crenulatum (De Coninck) Lentin and Williams emend. Heilmann-Clausen), the over all shape (strongly rounded pentagonal versus subshaerical to ellipsoidal), the prominence of the horns (always distinct in Krutzschidinium, sometimes reduced to almost lacking in Phthanoperidinium and size (overall lenght of the new genus under study 60 90 µm versus 30-50 µm of most Phthanoperidinium species).
The species of Apectodinium Costa and Downie, even those with penetabular arrangement of spines, show a non-variable I (2a) archaeopyle of quadra-style. These features also separate Wilsonidium Lentin and Williams from the new genus, which resembles it in parasutural distribution of spines. Trithyrodinium Drugg species have almost smooth surfaces but resemble Krutzschidinium in predominating archaeopyle type (3I) and cystnature.
Ginginodinium Cookson and Eisenack differs from the genus under study in having distinctly prominent paracingulum and parasulcus and in lacking parasutural arranged processes, although showing a similar outline and archaeopyle-type.
Trivalvadinium Islam is closely related to the new genus concerning the delicate cyst-nature, relationship of both phragma layers and the presence of a 3I (1a-3a) archaeopyle; however, prominent horns and parasutural arranged processes are lacking.
Nevertheless, both Trivalvadinium and Krutzschidinium seem to be in close relationship with Apectodinium plexus, because all three genera favour an environment with reduced salinity.
"Krutzschidinium", Strauss, 1991a, p.52,54. Name not validly published: no validly published species.
Type: Strauss, 1991a, pl.1, figs.a–b; text-fig.4c, as Krutzschidinium spinosum.
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Strauss, 1991]:
Diagnosis:
Cornucavate to slightly circumcavate cysts with a characteristically rounded pentagonal outline and a considerable dorsoventral compression.
One apical and two antapical distinct horns are located symmetrically to the longitudinal cyst-axis. They are triangular in shape with some spines giving them a more irregular branched appearance. Periphragm and endophragm are very delicate and pale and nearly always in close contact with one another except at the horn bases. Short, bulbose, spine-like processes arise from the periphragm and seem to be distributed in a parasutural pattern.
Cingulum and sulcus are broad, displaying almost no indentation, they may be bordered by parasutural rows of processes.
If decipherable, tabulation pattern is typically peridinoid: 4`, 3a, 7``, Xc, 5```, 2````, Xs, but often very incompletely developed.
Archaeopyle of variable type: the most common one is the 3I (1a-3a) - type, but archaeopyle formation rarely varies to include apicals (?tAtI) or to be a simple I (2a)-type.
Remarks:
The basic dorsal tabulation style seems to be a penta-style (compare Figs 3E, 3F and 3G with the figures on the plates), but outline of archaeopyle and run of other dorsal parasutures indicated by spiny crests also suggests the presence of quadra (and hexa?) style. Further observations are necessary to elucidate the real conditions.
Affinities:
The presence of variable archaeopyle type and parasutural arrangement of process-bearing crests makes Krutzschidinium most closely to the Phthanoperidinium - complex sensu Evitt (1985).
Significant differences between those two genera are the doubtless presence of a penta dorsal tabulation style in Krutzschidinium, the predominance of 3I-archaeopyle type (this type is not included in the emended diagnosis of Phthanoperidinium by Islam, 1982, although it is present, for instance, in P. crenulatum (De Coninck) Lentin and Williams emend. Heilmann-Clausen), the over all shape (strongly rounded pentagonal versus subshaerical to ellipsoidal), the prominence of the horns (always distinct in Krutzschidinium, sometimes reduced to almost lacking in Phthanoperidinium and size (overall lenght of the new genus under study 60 90 µm versus 30-50 µm of most Phthanoperidinium species).
The species of Apectodinium Costa and Downie, even those with penetabular arrangement of spines, show a non-variable I (2a) archaeopyle of quadra-style. These features also separate Wilsonidium Lentin and Williams from the new genus, which resembles it in parasutural distribution of spines. Trithyrodinium Drugg species have almost smooth surfaces but resemble Krutzschidinium in predominating archaeopyle type (3I) and cystnature.
Ginginodinium Cookson and Eisenack differs from the genus under study in having distinctly prominent paracingulum and parasulcus and in lacking parasutural arranged processes, although showing a similar outline and archaeopyle-type.
Trivalvadinium Islam is closely related to the new genus concerning the delicate cyst-nature, relationship of both phragma layers and the presence of a 3I (1a-3a) archaeopyle; however, prominent horns and parasutural arranged processes are lacking.
Nevertheless, both Trivalvadinium and Krutzschidinium seem to be in close relationship with Apectodinium plexus, because all three genera favour an environment with reduced salinity.