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Trithyrodinium
From Williams et al., 2017:
[Trithyrodinium, Drugg, 1967, p. 20; Emendations: Davey, 1969b, p. 10; Lentin and Williams, 1976, p. 98–100; Marheinecke, 1992, p. 94–95
Type species: Trithyrodinium evittii, Drugg, 1967, (pl.3, fig.2)]
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Original description: [Drugg, 1967]:
Description:
The same as for the genus Deflandrea Eisenack 1938, except that the archeopyle is formed by the removal of three intercalary plates rather than one plate as in Deflandrea. The three plates forming the operculum are removed as a unit.
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Emended descriptions:
Davey, 1969:
Description:
Cavate cysts consisting of a two-layered inner body surrounded by a single-layered outer wall which is produced into an apical and two antapical horns. Inner body subspherical, with opening formed by the removal of three intercalary plateareas. Tabulation may be present.
Archeopyle dorsal intercalary (2a).
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Lentin and Williams, 1976:
Description:
Shape: Pericyst: Ambitus ovoidal to pentagonal to elongate. Apex prolonged into a short apical horn with acuminate to rounded tip. Antapex procuced into one eccentrically located antapical horn, the left, or two symmetrically located antapical horns , which may be equal, or unequal when the right is always shorter. Pericyst widest in the precingular region. Epipericyst and hypopericyst of more or less equal size. Compression dorso-ventral.
Endocyst: Ambitus circular ovoidal or elliptical. Appressed to pericyst in precingular, cingular and postcingular regions. Isolated endocysts are not uncommon.
Pericoels: A small apical and one or two antapical pericoels.
Phragma: Periphragm: Thin. Surface laevigate.
Mesophragm: Present in some specimens when it is appressed to the endophragm.
Endophragm: Up to several microns thick. Surface laevigate, punctate, granulate, tuberculate or vermiculate.
Paratabulation: Pericyst: Paratabulation indeterminate other than in the vicinity of the periarchaeopyle when visible. The three anterior intercalaries indicate peridinoid paratabulation. Paraplates 1a and 3a are pentagonal in outline. 2a is a standard hexa.
Pericingulum: Generally present but weakly indicated by raised anterior and posterior parasutures.
Perisulcus: Weakly indicated on the hypopericyst.
Endocyst: Paratabulation indeterminate other than in the vicinity of the endoarchaeopyle. The three anterior intercalaries indicate peridinoid paratabulation. Paraplates 1a and 3a are pentagonal in outline, 2a is a standard hexa.
Archaeopyle: Periarchaeopyle: Frequently indeterminate. When visible is 3I intercalary resulting from the loss of all anterior intercalary paraplates, 1a, 2a and 3a; 2a is standard hexa. The perioperculum may be simple or compound, when it is seperated into the three individual paraplates.
Endoarchaeopyle: 3I intercalary resulting from the loss of all three anterior interalary paraplates, 1a, 2a and 3a; 2a is standard hexa. The endoperculum may be simple or compound, when it is seperated into the three individual paraplates. Endoperculum often remains in place.
Archaeopyle formula: 3I/3I
Dimensions:
Pericyst: Length 56-130 µm, breadth 47-80 µm. Endocyst: Length 41-81 µm.
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Marheinecke, 1992: (Translation: LPP):
Diagnosis:
Periblast: Pentagonal to sphaeroidal, no obvious compression. Apex rounded or ending in a short apical horn. Antapex rounded or straight. Two +/- equal antapical horns may be developed. Length/breadth ratio >/=1. Wall extremely thin, colourless, usually folded. Smooth or granulate. The granulation may be traced from the endoblast.
Endoblast: Pentagonal to sphaeroidal, closely appressed to the periblast except at the apical and antapical horns. Wall thick, light- or dark-brown. Pericoel: As cavity in the horns.
Areation: Indicated by cingulum and archaeopyle.
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Modified description:
Stover and Evitt 1978, p.127-128:
Synopsis:
Cysts proximate, cavate (when periphragm is intact), subspherical to ellipsoidal, usually with one short apical horn and two poorly developed antapical horns of nearly equal size; paratabulation more clearly indicated by endoarcheopyle than by periarcheopyle; archeopyle intercalary, Type 3I/3I; endoarcheopyle index >0.6.
Description:
Shape: Subspherical to ellipsoidal, usually with a short apical horn and two poorly developed antapical horns of nearly equal size; some forms may be compressed.
Wall relationships: Cornucavate, possibly circumcavate; periphragm may be partly or completely missing on some specimens.
Wall features: No parasutural features. Endophragm variously ornamented with features of low to moderate relief; periphragm smooth or faintly ornamented.
Paratabulation: Generally indicated by endoarcheopyle only; faint indications of a paracingulum may be present also Archeopyle. Intercalary, Type 3I/3I; periarcheopyle rarely discernible; endoarcheopyle formed by release of three paraplates, endoarcheopyle index >0.6; endoperculum free.
Paracingulum: Generally not indicated; position may be suggested by folds on the periphragm or by shallow local concavities at the lateral margins.
Parasulcus: Not indicated, or expressed as longitudinal folds on the perihypocyst.
Size: Intermediate to large.
Affinities:
Trithyrodinium differs from Deflandrea in having a 3I/3I rather than an I/I archeopyle.
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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.
Trithyrodinium Drugg, 1967, emend. Davey, 1969a, emend. Lentin and Williams, 1976, emend. Marheinhecke, 1992. Emendation from Marheinecke (1992, p.94-95), periblast pentagonal to spheroidal, not distinctly compressed. Apex rounded or extending into a short apical horn. Antapex rounded or straight. Two very small more or less symmetrical antapical horns may be present. Length:breadth ratio> or = 1. Wall extremely thin, colourless, usually lying in folds. Smooth or granulate. The granulation may be traced on the endoblast. Endoblast pentagonal to spheroidal, tightly appressed to the periblast everywhere except at the apical and antapical horns, which are formed exclusively by the periblast. Wall thick, light to very dark brown. Pericoels present as cavities in the horns. Tabulation indicated only by cingulum and archeopyle. Cingulum well formed in pentagonal specimens, less so in spheroidals. Planar or sinistral, displaced by up to one girdle width. The cingulum is manifested by two parallel folds. Sulcus may be indicated by corresponding concavity of the hypocyst. Periarcheopyle intercalary, 1a + 2a + 3a, operculum secate, solvate 1as+2as+3as, seldom foederate. Area 2a is iso to delta-linteloid (standard hexa to attenuated hexa of Lentin and Williams 1976). Archeopyle index > 0.7. Endoarcheopyle same as periarcheopyle.
[Trithyrodinium, Drugg, 1967, p. 20; Emendations: Davey, 1969b, p. 10; Lentin and Williams, 1976, p. 98–100; Marheinecke, 1992, p. 94–95
Type species: Trithyrodinium evittii, Drugg, 1967, (pl.3, fig.2)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Drugg, 1967]:
Description:
The same as for the genus Deflandrea Eisenack 1938, except that the archeopyle is formed by the removal of three intercalary plates rather than one plate as in Deflandrea. The three plates forming the operculum are removed as a unit.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Davey, 1969:
Description:
Cavate cysts consisting of a two-layered inner body surrounded by a single-layered outer wall which is produced into an apical and two antapical horns. Inner body subspherical, with opening formed by the removal of three intercalary plateareas. Tabulation may be present.
Archeopyle dorsal intercalary (2a).
---------------------------------------------------
Lentin and Williams, 1976:
Description:
Shape: Pericyst: Ambitus ovoidal to pentagonal to elongate. Apex prolonged into a short apical horn with acuminate to rounded tip. Antapex procuced into one eccentrically located antapical horn, the left, or two symmetrically located antapical horns , which may be equal, or unequal when the right is always shorter. Pericyst widest in the precingular region. Epipericyst and hypopericyst of more or less equal size. Compression dorso-ventral.
Endocyst: Ambitus circular ovoidal or elliptical. Appressed to pericyst in precingular, cingular and postcingular regions. Isolated endocysts are not uncommon.
Pericoels: A small apical and one or two antapical pericoels.
Phragma: Periphragm: Thin. Surface laevigate.
Mesophragm: Present in some specimens when it is appressed to the endophragm.
Endophragm: Up to several microns thick. Surface laevigate, punctate, granulate, tuberculate or vermiculate.
Paratabulation: Pericyst: Paratabulation indeterminate other than in the vicinity of the periarchaeopyle when visible. The three anterior intercalaries indicate peridinoid paratabulation. Paraplates 1a and 3a are pentagonal in outline. 2a is a standard hexa.
Pericingulum: Generally present but weakly indicated by raised anterior and posterior parasutures.
Perisulcus: Weakly indicated on the hypopericyst.
Endocyst: Paratabulation indeterminate other than in the vicinity of the endoarchaeopyle. The three anterior intercalaries indicate peridinoid paratabulation. Paraplates 1a and 3a are pentagonal in outline, 2a is a standard hexa.
Archaeopyle: Periarchaeopyle: Frequently indeterminate. When visible is 3I intercalary resulting from the loss of all anterior intercalary paraplates, 1a, 2a and 3a; 2a is standard hexa. The perioperculum may be simple or compound, when it is seperated into the three individual paraplates.
Endoarchaeopyle: 3I intercalary resulting from the loss of all three anterior interalary paraplates, 1a, 2a and 3a; 2a is standard hexa. The endoperculum may be simple or compound, when it is seperated into the three individual paraplates. Endoperculum often remains in place.
Archaeopyle formula: 3I/3I
Dimensions:
Pericyst: Length 56-130 µm, breadth 47-80 µm. Endocyst: Length 41-81 µm.
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Marheinecke, 1992: (Translation: LPP):
Diagnosis:
Periblast: Pentagonal to sphaeroidal, no obvious compression. Apex rounded or ending in a short apical horn. Antapex rounded or straight. Two +/- equal antapical horns may be developed. Length/breadth ratio >/=1. Wall extremely thin, colourless, usually folded. Smooth or granulate. The granulation may be traced from the endoblast.
Endoblast: Pentagonal to sphaeroidal, closely appressed to the periblast except at the apical and antapical horns. Wall thick, light- or dark-brown. Pericoel: As cavity in the horns.
Areation: Indicated by cingulum and archaeopyle.
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Modified description:
Stover and Evitt 1978, p.127-128:
Synopsis:
Cysts proximate, cavate (when periphragm is intact), subspherical to ellipsoidal, usually with one short apical horn and two poorly developed antapical horns of nearly equal size; paratabulation more clearly indicated by endoarcheopyle than by periarcheopyle; archeopyle intercalary, Type 3I/3I; endoarcheopyle index >0.6.
Description:
Shape: Subspherical to ellipsoidal, usually with a short apical horn and two poorly developed antapical horns of nearly equal size; some forms may be compressed.
Wall relationships: Cornucavate, possibly circumcavate; periphragm may be partly or completely missing on some specimens.
Wall features: No parasutural features. Endophragm variously ornamented with features of low to moderate relief; periphragm smooth or faintly ornamented.
Paratabulation: Generally indicated by endoarcheopyle only; faint indications of a paracingulum may be present also Archeopyle. Intercalary, Type 3I/3I; periarcheopyle rarely discernible; endoarcheopyle formed by release of three paraplates, endoarcheopyle index >0.6; endoperculum free.
Paracingulum: Generally not indicated; position may be suggested by folds on the periphragm or by shallow local concavities at the lateral margins.
Parasulcus: Not indicated, or expressed as longitudinal folds on the perihypocyst.
Size: Intermediate to large.
Affinities:
Trithyrodinium differs from Deflandrea in having a 3I/3I rather than an I/I archeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Trithyrodinium Drugg, 1967, emend. Davey, 1969a, emend. Lentin and Williams, 1976, emend. Marheinhecke, 1992. Emendation from Marheinecke (1992, p.94-95), periblast pentagonal to spheroidal, not distinctly compressed. Apex rounded or extending into a short apical horn. Antapex rounded or straight. Two very small more or less symmetrical antapical horns may be present. Length:breadth ratio> or = 1. Wall extremely thin, colourless, usually lying in folds. Smooth or granulate. The granulation may be traced on the endoblast. Endoblast pentagonal to spheroidal, tightly appressed to the periblast everywhere except at the apical and antapical horns, which are formed exclusively by the periblast. Wall thick, light to very dark brown. Pericoels present as cavities in the horns. Tabulation indicated only by cingulum and archeopyle. Cingulum well formed in pentagonal specimens, less so in spheroidals. Planar or sinistral, displaced by up to one girdle width. The cingulum is manifested by two parallel folds. Sulcus may be indicated by corresponding concavity of the hypocyst. Periarcheopyle intercalary, 1a + 2a + 3a, operculum secate, solvate 1as+2as+3as, seldom foederate. Area 2a is iso to delta-linteloid (standard hexa to attenuated hexa of Lentin and Williams 1976). Archeopyle index > 0.7. Endoarcheopyle same as periarcheopyle.