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Leptodinium subtile
Leptodinium subtile Klement, 1960, p.46-47
Taxonomic junior synonym: Gonyaulax (subsequently Leptodinium) freakei, according to Brenner (1988, p.60).
Holotype: Klement, 1960, pl.6, figs.1-2, text-figs.23-24
Locus typicus: Borehole Scherstetten 1.
Stratum typicum : Malm Gamma 2
Age: Early Kimmeridgian
Translation Klement 1960: GSC
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Leptodinium subtile Klement, 1960, is divided by the cingulum into a more thick-set epicyst and elongated hypocyst of the shape of a truncated pyramid. Other than the parasutures the beast is smooth. The parasutures between 1' and 4' and 4' and 6" as well as those between the sulcus and 6" range from being distinctly to completely reduced. Size: length 55-75 µm, breadth 52-68 µm.
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Original diagnosis: Klement 1960, p. 46: Leptodinium subtile
Typical species of the genus Leptodinium with elongated polyhedral theca, divided by a girdle furrow (which forms a strong spiral), into a more thick-set epitheca and into an elongated hypotheca of the shape of a truncated pyramid. Plates flat to only sliohtly convex. Sutures covered with slightly undular lists of medium breadth and smooth margins. Longitudinal furrow does not become wider to an appreciable extent on the hypotheca.
Original description: Klement 1960, p. 46, 47 : Leptodinium subtile
This species was found not infrequently and its represcntatives drew attention to them on the basis of their completely non-ornamented habitus, excepting the appearance of low sutural lists. The theca has an elongated - polyhedral shape and, by means of a girdle furrow (which forms a strong spiral), is separated into the more thick-set epitheca (which, possesses an apical prominence which in turn, has the appearance of being very slightly roof-shaped) and into the elongated hypotheca of a pronounced trapezium-like form which, antapically broadly truncated. The sutures are covered with smooth lists which are curved in a slightly undular manner and pos6ess an average width of about 4 microns. At the junction points of sutures at which two lists come to meet one another, we see strut-like thickenings which, however, do not stand out. What seems noteworthy here is the fact that the sutural lists between plates 1' and 4', 4' and 6", as well as those between the longitudinal furrow and plate 6", range from being distinctly reduced to being completely reduced. The plates of the armor (which range from being flat to, at the most, possessing a slightly convex form) show the following construction and distribution: The apical sector could be examined very closely and was found to be made up of four plates; of these plates, plate 1' , in the direct extension of which the longitudinal furrow is found, is elongated and together with the adjacent plate 4' takes up the ventral area of said sector, whereas plates 2' and 3' seem much more thick-set and form the dorsal segment of the apex region. Of the six pre-equatorial plates, plates 1'', 5 " and 6 " lie on the ventral side and show a trapezoidal contour. Plate 6 " is again distinctly reduced in length and in breadth and, in the direction toward the apex, borders in a slanted manner against plate 4'. On the other hand, plates 2 ", 3 " and 4 " make up the dorsal transition of the epitheca and have a pronounced trapezium-like shape. In the majority of the specimens, a pylome is found in the place of plate 3 ". The girdle furrow, of a width of 3-4 microns , is distally displaced by the relatively large amount of 2 to 2 times its own width. It is likewise flanked by undular lirts; marginally, it protrudes in a bulge-like manner, and it appears to be markedly indented. The longitudinal furrow extends from the 1st. apical plate to the antapex without essentially broadening on the hypotheca, in other words its margins run almost parallel to one another. No other differentiation marks of the furrow could be recognized. The hypotheca, which possesses the definite shape of a truncated pyramid , is made up of five post-equatorial plates, as well as of an accessory plate 1p and one polygonal antapical plate; between the lists which tower over the boundary sutures of said antapical plate the latter is indented on all sides. Compared to the other Postcingularplates, plates 1'''' and 5'''' are somerwhat reduced in size; the lower border of plate 1'''' borbers in a slanted manner against the intercalary plate 1p. Plates 2 " ', 3 "' and 4 "' lie dorsally and possess a pronounced trapezium-like form. The completely smooth membrane of the armor and the lists as well, display color tones ranging from light yellou to a light browmish coloration.
Relationships: In addition to the external habitus, a certain resemblance to the Gonyaulax amabilis DEFLANDRE exists; however, a close study of the tabulation brings to light considerable deviations. The number of postequatorial plates amounts to six in the case of the G. amabilis DEFLANDRE, which is in line with the tabulation scheme of the genus Gonyaulax, whereas in the present species we find only five post-equatorial plates. However, beyond this difference, also extensive differences in the structure of the apex region became apparent. In the case of the L. subtile, the 1st. apical plate lies in direct extension of the longitudinal furrow and not above the 6th. pre-equatorial plate , as stated explicitely in the case of the G. amabilis. Accordingly, compared to the L. subtile, also plates 2', 3' and 4' of the G. amabilis DEFLANDRE are shlfted in each case, which results in a completely different spatial arrangemant of the apical plates (and, due to the location of plate 4', also results in a different contour). As far as the species L. arcuatum is concerned, which will be discussed in the following, extensive morphological and complete structural analogies between it and the present species can be ascertained. However, the L. arcuatum is much more compact (broader than long) and has a larger size. Moreover, it possesses a distinctly rounded-off epitheca of a hemispherical fihape, with said epitheca being noticeably reduced in size in comparison to the elongated hypotheca. As far as the L. arcuatum is concerned, the decisive criterium from a differential-diagnostical viewpoint is the fact that the apex region has the shape of a wide arch, compared to the distinctly polygonal boundary of the apex region of the L. subtile.
Occurrence: Scherstetten 1: Sample No. S42b, S41: fieldom; nos. S37, S36, S35: in masses to frequently. Accordingly the main distribution lies in the Malm-Gamma. As far as the Langental-profile is concerned, no representatives of this fipecies could be ascertained, fiince said profile is limited to the Malm-Alpha.
Hörnle (Neuffen): N 386-N448 (Gamma): very frequently.
Bõratalsteige: B 1 (Upper-Gamma): seldom.
Dimensions: length/breadth-ratio lists (breadth)
(with lists)
holotype: 66:63 4
(the above values also represent the approximate average values)
paratypoids: 66:58 4.5
63:58 4
maximum: 75:66
minimum: 55:52
Number of available specimens: 200; of these, 29 particularly well preserved specimens were closely examined.
Taxonomic junior synonym: Gonyaulax (subsequently Leptodinium) freakei, according to Brenner (1988, p.60).
Holotype: Klement, 1960, pl.6, figs.1-2, text-figs.23-24
Locus typicus: Borehole Scherstetten 1.
Stratum typicum : Malm Gamma 2
Age: Early Kimmeridgian
Translation Klement 1960: GSC
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Leptodinium subtile Klement, 1960, is divided by the cingulum into a more thick-set epicyst and elongated hypocyst of the shape of a truncated pyramid. Other than the parasutures the beast is smooth. The parasutures between 1' and 4' and 4' and 6" as well as those between the sulcus and 6" range from being distinctly to completely reduced. Size: length 55-75 µm, breadth 52-68 µm.
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Original diagnosis: Klement 1960, p. 46: Leptodinium subtile
Typical species of the genus Leptodinium with elongated polyhedral theca, divided by a girdle furrow (which forms a strong spiral), into a more thick-set epitheca and into an elongated hypotheca of the shape of a truncated pyramid. Plates flat to only sliohtly convex. Sutures covered with slightly undular lists of medium breadth and smooth margins. Longitudinal furrow does not become wider to an appreciable extent on the hypotheca.
Original description: Klement 1960, p. 46, 47 : Leptodinium subtile
This species was found not infrequently and its represcntatives drew attention to them on the basis of their completely non-ornamented habitus, excepting the appearance of low sutural lists. The theca has an elongated - polyhedral shape and, by means of a girdle furrow (which forms a strong spiral), is separated into the more thick-set epitheca (which, possesses an apical prominence which in turn, has the appearance of being very slightly roof-shaped) and into the elongated hypotheca of a pronounced trapezium-like form which, antapically broadly truncated. The sutures are covered with smooth lists which are curved in a slightly undular manner and pos6ess an average width of about 4 microns. At the junction points of sutures at which two lists come to meet one another, we see strut-like thickenings which, however, do not stand out. What seems noteworthy here is the fact that the sutural lists between plates 1' and 4', 4' and 6", as well as those between the longitudinal furrow and plate 6", range from being distinctly reduced to being completely reduced. The plates of the armor (which range from being flat to, at the most, possessing a slightly convex form) show the following construction and distribution: The apical sector could be examined very closely and was found to be made up of four plates; of these plates, plate 1' , in the direct extension of which the longitudinal furrow is found, is elongated and together with the adjacent plate 4' takes up the ventral area of said sector, whereas plates 2' and 3' seem much more thick-set and form the dorsal segment of the apex region. Of the six pre-equatorial plates, plates 1'', 5 " and 6 " lie on the ventral side and show a trapezoidal contour. Plate 6 " is again distinctly reduced in length and in breadth and, in the direction toward the apex, borders in a slanted manner against plate 4'. On the other hand, plates 2 ", 3 " and 4 " make up the dorsal transition of the epitheca and have a pronounced trapezium-like shape. In the majority of the specimens, a pylome is found in the place of plate 3 ". The girdle furrow, of a width of 3-4 microns , is distally displaced by the relatively large amount of 2 to 2 times its own width. It is likewise flanked by undular lirts; marginally, it protrudes in a bulge-like manner, and it appears to be markedly indented. The longitudinal furrow extends from the 1st. apical plate to the antapex without essentially broadening on the hypotheca, in other words its margins run almost parallel to one another. No other differentiation marks of the furrow could be recognized. The hypotheca, which possesses the definite shape of a truncated pyramid , is made up of five post-equatorial plates, as well as of an accessory plate 1p and one polygonal antapical plate; between the lists which tower over the boundary sutures of said antapical plate the latter is indented on all sides. Compared to the other Postcingularplates, plates 1'''' and 5'''' are somerwhat reduced in size; the lower border of plate 1'''' borbers in a slanted manner against the intercalary plate 1p. Plates 2 " ', 3 "' and 4 "' lie dorsally and possess a pronounced trapezium-like form. The completely smooth membrane of the armor and the lists as well, display color tones ranging from light yellou to a light browmish coloration.
Relationships: In addition to the external habitus, a certain resemblance to the Gonyaulax amabilis DEFLANDRE exists; however, a close study of the tabulation brings to light considerable deviations. The number of postequatorial plates amounts to six in the case of the G. amabilis DEFLANDRE, which is in line with the tabulation scheme of the genus Gonyaulax, whereas in the present species we find only five post-equatorial plates. However, beyond this difference, also extensive differences in the structure of the apex region became apparent. In the case of the L. subtile, the 1st. apical plate lies in direct extension of the longitudinal furrow and not above the 6th. pre-equatorial plate , as stated explicitely in the case of the G. amabilis. Accordingly, compared to the L. subtile, also plates 2', 3' and 4' of the G. amabilis DEFLANDRE are shlfted in each case, which results in a completely different spatial arrangemant of the apical plates (and, due to the location of plate 4', also results in a different contour). As far as the species L. arcuatum is concerned, which will be discussed in the following, extensive morphological and complete structural analogies between it and the present species can be ascertained. However, the L. arcuatum is much more compact (broader than long) and has a larger size. Moreover, it possesses a distinctly rounded-off epitheca of a hemispherical fihape, with said epitheca being noticeably reduced in size in comparison to the elongated hypotheca. As far as the L. arcuatum is concerned, the decisive criterium from a differential-diagnostical viewpoint is the fact that the apex region has the shape of a wide arch, compared to the distinctly polygonal boundary of the apex region of the L. subtile.
Occurrence: Scherstetten 1: Sample No. S42b, S41: fieldom; nos. S37, S36, S35: in masses to frequently. Accordingly the main distribution lies in the Malm-Gamma. As far as the Langental-profile is concerned, no representatives of this fipecies could be ascertained, fiince said profile is limited to the Malm-Alpha.
Hörnle (Neuffen): N 386-N448 (Gamma): very frequently.
Bõratalsteige: B 1 (Upper-Gamma): seldom.
Dimensions: length/breadth-ratio lists (breadth)
(with lists)
holotype: 66:63 4
(the above values also represent the approximate average values)
paratypoids: 66:58 4.5
63:58 4
maximum: 75:66
minimum: 55:52
Number of available specimens: 200; of these, 29 particularly well preserved specimens were closely examined.