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Leptodinium
From Williams et al., 2017:
[Leptodinium, Klement, 1960, p. 45–46; Emendations: Sarjeant, 1966b, p. 133; Wall, 1967, p. 104; Sarjeant, 1969, p. 11–12; Stover and Evitt, 1978, p. 169–170; Sarjeant, 1982b, p. 37-38
Type species: Leptodinium subtile, Klement, 1960 (pl.6, figs.1–2; text-figs.23–24)]
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Original description: [Klement, 1960]: (Translation: Stover and Evitt, 1978, p. 169):
Diagnosis:
Elongated to compact polyhedral or oval, rounded theca, without ornamentation by spines or wringed fringes, tabulation according to the following scheme: 4`, 6``, 5```, 1p, 1````. Apex without horn. Plates plane to convex. Sutures ornamented with low to moderately high ledges. Spiral girdle furrow. Longitudinal furrow in direct continuation of the first apical plate and extending to the antapex, undifferentiated or divided into 1 upper, 5 middle and 1 lower plate.
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Emended description:
Sarjeant, 1966:
Diagnosis:
Proximate dinoflagellate cysts, spherical, ovoidal, ellipsoidal or polyhedral, with the tabulation 4`, 6``, 5-?6g, 5```, 1p, 1````. Cingulum strongly or weakly helicoid, sulcus generally but not constantly extending on to epitract, undivided or subdivided into a pattern of ventral plates. Sutures between plates in form of low ridges, or bearing crests of varied form (smooth, denticulate or spinous; perforate or imperforate). Height of crests always less than1/4 of shell width. Surface of shell smooth, granular or punctate. Precingular archaeopyle formed by loss of plate 3``; not all individuals may show an archaeopyle.
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Wall, 1967:
Description:
Ovoid, spherical, or polyhedral tests ornamented with more or less level, low sutural septa (but not with spines), developed from the outer of a two-layered wall, reflecting a tabulation of 3-4`, Oa, 6", 6g, 5-6"`, 1p, 1"". Girdle spiral, ventral sulcus only just extending on to the epitheca
and in contact with 1`.
Archeopyle dorsal and precingular (3"). Apical and antapical projections essentially absent.
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Sarjeant in Davey et al. 1969:
Description:
Proximate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polyhedral, with reflected tabulation 3-4`, O-la, 6", 6c, 5-6"`, 1p, O-l p.v., 1"", O-x s. Apical, median and antapical horns lacking. Cingulum strongly or weakly helicoid, laevorotatory; cingular plates well or poorly marked. Sulcus generally but not constantly extending onto epitract, undivided or subdivided into a variable number of small plates. Rarely, an apical or an antapical pericoel may be present (but not both); the two shell layers are otherwise in continuous contact. Sutures typically marked by ridges or low crests (perforate or imperforate), without spines or denticles. Height of crests always less (and typically markedly less) than 1/4 of shell width. A precingular single-plate archaeopyle, formed by loss of plate 3", is developed, the operculum typically becoming wholly detached; in some specimens, the archaeopyle may not be developed. Surface of periphragm smooth, granular, or punctate. Forms with nodose or reticulate surface have not been encountered and forms with crest spines or with general spine cover are excluded.
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Stover and Evitt 1978:
Synopsis:
Cysts proximochorate, ellipsoidal to subpolygonal, with or without an apical projection or horn. Paratabulation gonyaulacacean, indicated by parasutural septa only; paraplate 4` characteristically shorter than 1`, and contact with four- or five-sided paraplate 6`` substantial; archeopyle precingular, Type P.
Description:
Shape: Ellipsoidal to polygonal; body tends to be somewhat elongate with an angular outline; apical protrusion may be present.
Wall relationships: Generally autophragm only, occasionally local indications of two wall layers may be present.
Wall features: Parasutural septa smooth and imperforate or perforate, and of approximately uniform height; crests normally smooth; area between septa smooth or with features of low relief.
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 4`, 0-2a, 6``, X-6c, 5-6```, 1p, 1````, 0-5s. Septum normally present between paraplates 1` and 4`, the latter nearly always shorter than the former; line of contact substantial between 4` and four- or five-sided 6`` paraplate, and one or more intercalary paraplates may be present.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by parallel transverse septa or by six rectangular paraplates; ventral ends moderately to strongly offset.
Parasulcus: Normally delimited by parasutural septa and may be subdivided.
Size: Intermediate to large.
Affinities:
Leptodinium differs from Impagidinium in having the fourth apical paraplate clearly separated from and shorter than the first apical paraplate. In addition, the line of contact between paraplates 4` and 6" is normally appreciably greater than it is in Impagidinium, and the sixth precingular paraplate is quadrangular or pentangular rather than subtriangular. In general, species of Leptodinium tend to be elliptical to somewhat polygonal in outline, to possess an apical protrusion or horn, and to have the paratabulation expressed completely or nearly so. Species of Impagidinium, in contrast, are normally circular or elliptical in outline, lack an apical projection, and may have much reduced paratabulation.
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Sarjeant, 1982:
Diagnosis:
Proximate to proximochorate dinoflagellate cysts normally of small to intermediate, rarely of large, size. Ambitus spheroidal or ovoidal to ellipsoidal or subpolygonal. Apex apically rounded, sometimes bearing a mamelon but lacking a true apical horn. Cavation lacking, at the apex or elsewhere.
Paratabulation ?0pa, 4`, 0-2a, 6``, 6c-?7c, 6```, 1p, 1````; the sulcus may also show subdivision into paraplates. Paraplate 4` is quite large and roughly quadrate, having a moderately long boundary with a reduced 6``. The boundary between 4` and 6`` intersects with the right lateral boundary of 1` in a position anterior to the junction of the latter paraplate with the sulcus. Cingulum moderately to strongly helicoid; between its two ends, the sulcus is typically straight. Parasutures marked by lines or crests of a height that is variable but always less than 1/4 of the cyst width; their distal edges are typically smooth to slightly undulose but may show denticulations or serrations of low amplitude. Accessory crests lacking; gonal spines are not developed. Surface of cyst typically smooth or exhibiting features of low relief.
Archaeopyle single-plate precingular, formed by loss of paraplate 3``; operculum reduced.
Affinities:
Leptodinium resembles Rhynchodiniopsis in most features of its paratabulation but differs in the lack of an apical horn, of cavation and of gonal spines; the crests tend to be simpler in character.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP
Leptodinium Klement, 1960, emend. Stover and Evitt, 1978, emend. Sarjeant, 1982b. synopsis from Stover and Evitt (1978, p.169). Cysts proximochorate, ellipsoidal to subpolygonal, with or without an apical projection or horn. Paratabulation gonyaulacacean, indicated by parasutural septa only; paraplate 4` characteristically shorter than 1`, and contact with four- or five-sided paraplate 6" substantial; archeopyle precingular, type P.
[Leptodinium, Klement, 1960, p. 45–46; Emendations: Sarjeant, 1966b, p. 133; Wall, 1967, p. 104; Sarjeant, 1969, p. 11–12; Stover and Evitt, 1978, p. 169–170; Sarjeant, 1982b, p. 37-38
Type species: Leptodinium subtile, Klement, 1960 (pl.6, figs.1–2; text-figs.23–24)]
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Original description: [Klement, 1960]: (Translation: Stover and Evitt, 1978, p. 169):
Diagnosis:
Elongated to compact polyhedral or oval, rounded theca, without ornamentation by spines or wringed fringes, tabulation according to the following scheme: 4`, 6``, 5```, 1p, 1````. Apex without horn. Plates plane to convex. Sutures ornamented with low to moderately high ledges. Spiral girdle furrow. Longitudinal furrow in direct continuation of the first apical plate and extending to the antapex, undifferentiated or divided into 1 upper, 5 middle and 1 lower plate.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Sarjeant, 1966:
Diagnosis:
Proximate dinoflagellate cysts, spherical, ovoidal, ellipsoidal or polyhedral, with the tabulation 4`, 6``, 5-?6g, 5```, 1p, 1````. Cingulum strongly or weakly helicoid, sulcus generally but not constantly extending on to epitract, undivided or subdivided into a pattern of ventral plates. Sutures between plates in form of low ridges, or bearing crests of varied form (smooth, denticulate or spinous; perforate or imperforate). Height of crests always less than1/4 of shell width. Surface of shell smooth, granular or punctate. Precingular archaeopyle formed by loss of plate 3``; not all individuals may show an archaeopyle.
------------------------------------------
Wall, 1967:
Description:
Ovoid, spherical, or polyhedral tests ornamented with more or less level, low sutural septa (but not with spines), developed from the outer of a two-layered wall, reflecting a tabulation of 3-4`, Oa, 6", 6g, 5-6"`, 1p, 1"". Girdle spiral, ventral sulcus only just extending on to the epitheca
and in contact with 1`.
Archeopyle dorsal and precingular (3"). Apical and antapical projections essentially absent.
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Sarjeant in Davey et al. 1969:
Description:
Proximate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polyhedral, with reflected tabulation 3-4`, O-la, 6", 6c, 5-6"`, 1p, O-l p.v., 1"", O-x s. Apical, median and antapical horns lacking. Cingulum strongly or weakly helicoid, laevorotatory; cingular plates well or poorly marked. Sulcus generally but not constantly extending onto epitract, undivided or subdivided into a variable number of small plates. Rarely, an apical or an antapical pericoel may be present (but not both); the two shell layers are otherwise in continuous contact. Sutures typically marked by ridges or low crests (perforate or imperforate), without spines or denticles. Height of crests always less (and typically markedly less) than 1/4 of shell width. A precingular single-plate archaeopyle, formed by loss of plate 3", is developed, the operculum typically becoming wholly detached; in some specimens, the archaeopyle may not be developed. Surface of periphragm smooth, granular, or punctate. Forms with nodose or reticulate surface have not been encountered and forms with crest spines or with general spine cover are excluded.
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Stover and Evitt 1978:
Synopsis:
Cysts proximochorate, ellipsoidal to subpolygonal, with or without an apical projection or horn. Paratabulation gonyaulacacean, indicated by parasutural septa only; paraplate 4` characteristically shorter than 1`, and contact with four- or five-sided paraplate 6`` substantial; archeopyle precingular, Type P.
Description:
Shape: Ellipsoidal to polygonal; body tends to be somewhat elongate with an angular outline; apical protrusion may be present.
Wall relationships: Generally autophragm only, occasionally local indications of two wall layers may be present.
Wall features: Parasutural septa smooth and imperforate or perforate, and of approximately uniform height; crests normally smooth; area between septa smooth or with features of low relief.
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 4`, 0-2a, 6``, X-6c, 5-6```, 1p, 1````, 0-5s. Septum normally present between paraplates 1` and 4`, the latter nearly always shorter than the former; line of contact substantial between 4` and four- or five-sided 6`` paraplate, and one or more intercalary paraplates may be present.
Archeopyle: Precingular, Type P (3`` only); operculum free.
Paracingulum: Indicated by parallel transverse septa or by six rectangular paraplates; ventral ends moderately to strongly offset.
Parasulcus: Normally delimited by parasutural septa and may be subdivided.
Size: Intermediate to large.
Affinities:
Leptodinium differs from Impagidinium in having the fourth apical paraplate clearly separated from and shorter than the first apical paraplate. In addition, the line of contact between paraplates 4` and 6" is normally appreciably greater than it is in Impagidinium, and the sixth precingular paraplate is quadrangular or pentangular rather than subtriangular. In general, species of Leptodinium tend to be elliptical to somewhat polygonal in outline, to possess an apical protrusion or horn, and to have the paratabulation expressed completely or nearly so. Species of Impagidinium, in contrast, are normally circular or elliptical in outline, lack an apical projection, and may have much reduced paratabulation.
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Sarjeant, 1982:
Diagnosis:
Proximate to proximochorate dinoflagellate cysts normally of small to intermediate, rarely of large, size. Ambitus spheroidal or ovoidal to ellipsoidal or subpolygonal. Apex apically rounded, sometimes bearing a mamelon but lacking a true apical horn. Cavation lacking, at the apex or elsewhere.
Paratabulation ?0pa, 4`, 0-2a, 6``, 6c-?7c, 6```, 1p, 1````; the sulcus may also show subdivision into paraplates. Paraplate 4` is quite large and roughly quadrate, having a moderately long boundary with a reduced 6``. The boundary between 4` and 6`` intersects with the right lateral boundary of 1` in a position anterior to the junction of the latter paraplate with the sulcus. Cingulum moderately to strongly helicoid; between its two ends, the sulcus is typically straight. Parasutures marked by lines or crests of a height that is variable but always less than 1/4 of the cyst width; their distal edges are typically smooth to slightly undulose but may show denticulations or serrations of low amplitude. Accessory crests lacking; gonal spines are not developed. Surface of cyst typically smooth or exhibiting features of low relief.
Archaeopyle single-plate precingular, formed by loss of paraplate 3``; operculum reduced.
Affinities:
Leptodinium resembles Rhynchodiniopsis in most features of its paratabulation but differs in the lack of an apical horn, of cavation and of gonal spines; the crests tend to be simpler in character.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP
Leptodinium Klement, 1960, emend. Stover and Evitt, 1978, emend. Sarjeant, 1982b. synopsis from Stover and Evitt (1978, p.169). Cysts proximochorate, ellipsoidal to subpolygonal, with or without an apical projection or horn. Paratabulation gonyaulacacean, indicated by parasutural septa only; paraplate 4` characteristically shorter than 1`, and contact with four- or five-sided paraplate 6" substantial; archeopyle precingular, type P.