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Pseudoceratium
From Williams et al., 2017:
[Pseudoceratium, Gocht, 1957, p. 166; Emendations: Dörhöfer and Davies, 1980, p. 39; Bint, 1986, p. 144-145; Helby, 1987, p. 313–315.
Tax. jr. syn.: Aptea, according to Bint (1986, p.144) — however, Quattrocchio and Sarjeant (1992, p.2–234) retained Aptea; Endoceratium, according to Helby (1987, p.313–315) — however, Lentin and Williams (1989, p.125) retained Endoceratium.
Type species: Pseudoceratium pelliferum, Gocht, 1957 (pl.18, fig.1)] ; emend. Dörhöfer and Davies, 1980
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Original description: [Gocht, 1957]: (Translation: Stover and Evitt, 1978, p.77):
Diagnosis:
Shell of organic material, of peridinioid shape (due to several more or less drawn-out horns), unplated, without girdle system, ring-suture or furrow formation. Shell smooth or covered with short processes.
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Modified description:
Stover and Evitt 1978, p. 77-78:
Synopsis:
Cysts proximate, compressed ceratioid with three well-developed horns, one apical, one antapical, and one cingular or postcingular horn; autophragm smooth, granular, or with dense, short processes; archeopyle apical, Type tA; parasulcal notch offset.
Description:
Shape: Compressed ceratioid with an apical, an antapical, and a shorter cingular or postcingular horn.
Wall relationships: Autophragm only.
Wall features: parasutural features generally absent; occasionally expressed by faint alignment of slightly longer processes. Autophragm with dense, short, generally knobby, bifurcate, or distally branched processes. Paratabulation: Usually indicated by archeopyle only, or incompletely by faint alignment of processes. Formula indeterminate; that given by Neale and Sarjeant (1962) anomalous, derived from misinterpretation.
Archeopyle: Apical, Type tA; principally archeopyle suture zigzag; parasulcal notch offset; operculum free.
Paracingulum: Not indicated, or expressed by transverse alignment of longer processes.
Parasulcus: Generally not indicated, or expressed as a less densely ornamented area.
Size: Intermediate to large.
Affinities:
Pseudoceratium differs from Odontochitina in having shorter horns and a more strongly ornamented autophragm, and in not being cavate. It differs from Aptea in having generally longer horns and uniformly distributed ornamentation. In Aptea the horns on the hypocyst may be reduced appreciably so that its outline may be nearly semicircular, and the ornamentation may be less developed in the middorsal and midventral areas then elsewhere. Forms intermediate between typically Pseudoceratium and typically Aptea can be expected. Endoceratium differs from Pseudoceratium in being cavate and in having the paratabulation indicated by parasutural ridges.
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Emended descriptions:
Dörhöfer and Davies, 1980:
Diagnosis:
Dorsoventrally flattened proximate dinoflagellate cyst of asymmetrical triangular shape with three long horns in apical, antapical and postcingular positions. A fourth (left postcingular) is occasionally weakly developed. Ornament apteate, consisting of peni- and infratabular elements. Tabulation traces occasionally apparent, formula: 4`, 2a, 6``, 5-6c, 6```, 1````, ?3-6s.
Archaeopyle: (4A2I), operculum occasionally attached ventrally.
Affinities:
Pseudoceratium is emended to have apteate ornament, and intercalary plates. Odontochitina is smooth and cavate. The sole difference between Pseudoceratium and Aptea is the length of the horns which are reduced in Aptea. If this feature should prove not to justify generic separation, Aptea would become a junior synonym. Muderongia and Phoberocysta approach bilateral symmetry by exhibiting two distinct postcingular horns.
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Bint, 1986:
Description:
Intermediate to large dorso-ventrally compressed cysts with ceratioid outline and three horns: apical, antapical and right lateral. Horns may be long, short, or reduced to low rounded bulges. Right lateral horn is postcingular but may include part of the cingulum also; it is usually the least prominent of the three horns and may be greatly reduced. Smaller bulges may occur at left lateral (cingular) position and between the antapical and right postcingular horns (i.e. right antapical).
Autophragm only or autophragm plus ectophragm. Autophragm ornamented with variable, generally low, usually flat-topped, and sometimes coalescing processes which may be connected distally by an ectophragm. Ornament may be reduced on the mid-ventral and mid-dorsal surfaces.
Archaeopyle apical, type (tA), operculum usually free. Archaeopyle suture zigzag, sulcal notch offset to the left.
Paratabulation may be incompletely indicated by alignment of processes, interpreted formula 4`, 6``, Xc, ?6```, 1p, 1````.
Cingulum may be indicated, or expressed as a vague depression with less dense ornament.
Affinities:
Pseudoceratium is most similar to Endoceratium Vozzhennikova 1965, which differs in being circumcavate and typically lacks connecting structures between the two walls. Cyclonephelium Deflandre and Cookson 1955 differs from short horned species of Pseudoceratium by having no consistent indication of a right lateral horn.
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Helby, 1987:
Description:
Shape: compressed ceratioid with single apical, antapical and postcingular horns.
Wall relationships: Cyst comprised of 1 or 2 layers, either as autophragm or autophragm with ectophragm or endophragm and periphragm. Two layered cysts may be circumcavate with the distance between wall layers varying substantially or holocavate also with substantial variation in the separation of the layers. Such variation occurs between species, seldom within populations.
Wall features: Endophragm and ectophragm surfaces may display minor parasutural to pandasutural features, but are otherwise uniformly smooth, granulate or reticulate. Autophragm may bear projections, varying from nontabular and densely packed to distinctly penitabular. Shape of processes variable but commonly distally branched and connected by trabeculae.
Archaeopyle: Apical, type (tA), principal archaeopyle suture zigzag; parasutural notch offset; operculum normally free.
Paratabulation: May be indicated by parasutural, pandasutural or penitabular features, and by the archaeopyle; ceratiacean, formula 4`, 6``, ?c, 6```, 1p, 1````.
Paracingulum: May be indicated by low, sub-parallel ridges or differentiation (scabration, granulation or thickening) of dorsal surface of endophragm or ectophragm, or by longer processes (parasutural or pandasutural) on the autophragm.
Parasulcus: Usually not well defined, sinuous, twisting from left ventral position on epicyst to a midventral position on the hypocyst.
Size: Intermediate to large.
Affinities:
(Annotated) Traditional distinctions between Endoceratium and Pseudoceratium are no longer valid and, on the basis of reported form-variations, Endoceratium is regarded as a junior synonym.
Pseudoceratium is distinguished from Aptea by reduced hypocystal horns of the latter, although the range of variation in Aptea suggests that it will be increasingly difficult to maintain separation of these genera.
Odontochitina has much longer, usually thinner and more pointed horns and is cornucavate.
Xenescus is cornucavate and the periphragm bears prominent parasutural and nontabular processes.
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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.
Gocht, 1957, emend. Dörhöfer and Davies, 1980, emend. Bint, 1986, emend. Helby, 1987. Diagnosis from Helby (1987, p.313) as follows, Shape. Compressed ceratioid with single apical, antapical and postcingular horns. Wall relationships; cyst comprised of 1 or 2 layers, either as autophragm or autophragm with ectophragm or endophragm and periphragm. Two layered cysts may be circumcavate with the distance between wall layers varying substantially or holocavate also with substantial variation in the separation of the layers. Such variation occurs between species, seldom within populations. Wall features. Endophragm and ectophragm surfaces may display minor parasutural to pandasutural features, but are otherwise uniformly smooth, granulate or reticulate. Autophragm may bear projections, varying from nontabular and densely packed to distinctly penitabular. Shape of processes variable but commonly distally branched and connected by trabeculae. Archeopyle. Apical, type [tA], principal archeopyle suture zigzag; parasulcal notch offset; operculum normally free. Paratabulation. May be indicated by parasutural pandasutural or penitabular features, and by the archeopyle; ceratiacean, formula 4`, 6", ?c, 6``` , 1p, 1````. Paracingulum. May be indicated by low, subparallel ridges or differentiations (scabration, granulation or thickening) of dorsal surface of endophragm or ectophragm, or by longer processes (parasutural or pandasutural) on the autophragm. Parasulcus. Usually not well defined, sinuous, twisting from left ventral position on epicyst to a midventral position on the hypocyst. Size intermediate to large. Helby considered Endoceratium to be a taxonomic junior synonym of Pseudoceratium.
[Pseudoceratium, Gocht, 1957, p. 166; Emendations: Dörhöfer and Davies, 1980, p. 39; Bint, 1986, p. 144-145; Helby, 1987, p. 313–315.
Tax. jr. syn.: Aptea, according to Bint (1986, p.144) — however, Quattrocchio and Sarjeant (1992, p.2–234) retained Aptea; Endoceratium, according to Helby (1987, p.313–315) — however, Lentin and Williams (1989, p.125) retained Endoceratium.
Type species: Pseudoceratium pelliferum, Gocht, 1957 (pl.18, fig.1)] ; emend. Dörhöfer and Davies, 1980
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Original description: [Gocht, 1957]: (Translation: Stover and Evitt, 1978, p.77):
Diagnosis:
Shell of organic material, of peridinioid shape (due to several more or less drawn-out horns), unplated, without girdle system, ring-suture or furrow formation. Shell smooth or covered with short processes.
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Modified description:
Stover and Evitt 1978, p. 77-78:
Synopsis:
Cysts proximate, compressed ceratioid with three well-developed horns, one apical, one antapical, and one cingular or postcingular horn; autophragm smooth, granular, or with dense, short processes; archeopyle apical, Type tA; parasulcal notch offset.
Description:
Shape: Compressed ceratioid with an apical, an antapical, and a shorter cingular or postcingular horn.
Wall relationships: Autophragm only.
Wall features: parasutural features generally absent; occasionally expressed by faint alignment of slightly longer processes. Autophragm with dense, short, generally knobby, bifurcate, or distally branched processes. Paratabulation: Usually indicated by archeopyle only, or incompletely by faint alignment of processes. Formula indeterminate; that given by Neale and Sarjeant (1962) anomalous, derived from misinterpretation.
Archeopyle: Apical, Type tA; principally archeopyle suture zigzag; parasulcal notch offset; operculum free.
Paracingulum: Not indicated, or expressed by transverse alignment of longer processes.
Parasulcus: Generally not indicated, or expressed as a less densely ornamented area.
Size: Intermediate to large.
Affinities:
Pseudoceratium differs from Odontochitina in having shorter horns and a more strongly ornamented autophragm, and in not being cavate. It differs from Aptea in having generally longer horns and uniformly distributed ornamentation. In Aptea the horns on the hypocyst may be reduced appreciably so that its outline may be nearly semicircular, and the ornamentation may be less developed in the middorsal and midventral areas then elsewhere. Forms intermediate between typically Pseudoceratium and typically Aptea can be expected. Endoceratium differs from Pseudoceratium in being cavate and in having the paratabulation indicated by parasutural ridges.
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Emended descriptions:
Dörhöfer and Davies, 1980:
Diagnosis:
Dorsoventrally flattened proximate dinoflagellate cyst of asymmetrical triangular shape with three long horns in apical, antapical and postcingular positions. A fourth (left postcingular) is occasionally weakly developed. Ornament apteate, consisting of peni- and infratabular elements. Tabulation traces occasionally apparent, formula: 4`, 2a, 6``, 5-6c, 6```, 1````, ?3-6s.
Archaeopyle: (4A2I), operculum occasionally attached ventrally.
Affinities:
Pseudoceratium is emended to have apteate ornament, and intercalary plates. Odontochitina is smooth and cavate. The sole difference between Pseudoceratium and Aptea is the length of the horns which are reduced in Aptea. If this feature should prove not to justify generic separation, Aptea would become a junior synonym. Muderongia and Phoberocysta approach bilateral symmetry by exhibiting two distinct postcingular horns.
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Bint, 1986:
Description:
Intermediate to large dorso-ventrally compressed cysts with ceratioid outline and three horns: apical, antapical and right lateral. Horns may be long, short, or reduced to low rounded bulges. Right lateral horn is postcingular but may include part of the cingulum also; it is usually the least prominent of the three horns and may be greatly reduced. Smaller bulges may occur at left lateral (cingular) position and between the antapical and right postcingular horns (i.e. right antapical).
Autophragm only or autophragm plus ectophragm. Autophragm ornamented with variable, generally low, usually flat-topped, and sometimes coalescing processes which may be connected distally by an ectophragm. Ornament may be reduced on the mid-ventral and mid-dorsal surfaces.
Archaeopyle apical, type (tA), operculum usually free. Archaeopyle suture zigzag, sulcal notch offset to the left.
Paratabulation may be incompletely indicated by alignment of processes, interpreted formula 4`, 6``, Xc, ?6```, 1p, 1````.
Cingulum may be indicated, or expressed as a vague depression with less dense ornament.
Affinities:
Pseudoceratium is most similar to Endoceratium Vozzhennikova 1965, which differs in being circumcavate and typically lacks connecting structures between the two walls. Cyclonephelium Deflandre and Cookson 1955 differs from short horned species of Pseudoceratium by having no consistent indication of a right lateral horn.
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Helby, 1987:
Description:
Shape: compressed ceratioid with single apical, antapical and postcingular horns.
Wall relationships: Cyst comprised of 1 or 2 layers, either as autophragm or autophragm with ectophragm or endophragm and periphragm. Two layered cysts may be circumcavate with the distance between wall layers varying substantially or holocavate also with substantial variation in the separation of the layers. Such variation occurs between species, seldom within populations.
Wall features: Endophragm and ectophragm surfaces may display minor parasutural to pandasutural features, but are otherwise uniformly smooth, granulate or reticulate. Autophragm may bear projections, varying from nontabular and densely packed to distinctly penitabular. Shape of processes variable but commonly distally branched and connected by trabeculae.
Archaeopyle: Apical, type (tA), principal archaeopyle suture zigzag; parasutural notch offset; operculum normally free.
Paratabulation: May be indicated by parasutural, pandasutural or penitabular features, and by the archaeopyle; ceratiacean, formula 4`, 6``, ?c, 6```, 1p, 1````.
Paracingulum: May be indicated by low, sub-parallel ridges or differentiation (scabration, granulation or thickening) of dorsal surface of endophragm or ectophragm, or by longer processes (parasutural or pandasutural) on the autophragm.
Parasulcus: Usually not well defined, sinuous, twisting from left ventral position on epicyst to a midventral position on the hypocyst.
Size: Intermediate to large.
Affinities:
(Annotated) Traditional distinctions between Endoceratium and Pseudoceratium are no longer valid and, on the basis of reported form-variations, Endoceratium is regarded as a junior synonym.
Pseudoceratium is distinguished from Aptea by reduced hypocystal horns of the latter, although the range of variation in Aptea suggests that it will be increasingly difficult to maintain separation of these genera.
Odontochitina has much longer, usually thinner and more pointed horns and is cornucavate.
Xenescus is cornucavate and the periphragm bears prominent parasutural and nontabular processes.
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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.
Gocht, 1957, emend. Dörhöfer and Davies, 1980, emend. Bint, 1986, emend. Helby, 1987. Diagnosis from Helby (1987, p.313) as follows, Shape. Compressed ceratioid with single apical, antapical and postcingular horns. Wall relationships; cyst comprised of 1 or 2 layers, either as autophragm or autophragm with ectophragm or endophragm and periphragm. Two layered cysts may be circumcavate with the distance between wall layers varying substantially or holocavate also with substantial variation in the separation of the layers. Such variation occurs between species, seldom within populations. Wall features. Endophragm and ectophragm surfaces may display minor parasutural to pandasutural features, but are otherwise uniformly smooth, granulate or reticulate. Autophragm may bear projections, varying from nontabular and densely packed to distinctly penitabular. Shape of processes variable but commonly distally branched and connected by trabeculae. Archeopyle. Apical, type [tA], principal archeopyle suture zigzag; parasulcal notch offset; operculum normally free. Paratabulation. May be indicated by parasutural pandasutural or penitabular features, and by the archeopyle; ceratiacean, formula 4`, 6", ?c, 6``` , 1p, 1````. Paracingulum. May be indicated by low, subparallel ridges or differentiations (scabration, granulation or thickening) of dorsal surface of endophragm or ectophragm, or by longer processes (parasutural or pandasutural) on the autophragm. Parasulcus. Usually not well defined, sinuous, twisting from left ventral position on epicyst to a midventral position on the hypocyst. Size intermediate to large. Helby considered Endoceratium to be a taxonomic junior synonym of Pseudoceratium.