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Acanthaulax aculeata
Acanthaulax aculeata, (Klement, 1960, p. 42, pl. 5, figs. 6-9; text-fig. 21), Stover and Evitt, 1978, p. 137.
NOW Tehamadinium. Originally Gonyaulax, subsequently Gonyaulacysta, thirdly Acanthaulax, fourthly Occisucysta, fifthly (and now) Tehamadinium.
Holotype: Klement, 1960, pl.5, figs.6-7.
Age: Early Kimmeridgian.
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Original description as Gonyaulax aculeata: [Klement 1960, p. 42]:
Diagnosis:
A species of the genus Gonyaulax with the following tabulation scheme: 4', 6", 6 " ', 1p, 1 ppl, 1''''. Ovaloidal envelope, slightly flattened ventrally,with short apex protuberance which is as thin as a thread. Plates range from being flat to being slightly convex, in part, ornamented with vermicular, irregularly distributed, snort tubercle-sutures. Sutures are covered with low, tuberculated lists , bearing closely spaced, short spines which, distally, are thickened in a knobuar manner. Helicoidal transversal furrow, displaced distally by slightly more than 1 times its own width. (Transversal furrow width = about 4 microns). Longitudinal furrow widened on hypotheca, with intercalary lower plate.
Description:
This species, which shows a very characteristic type of development and, for this reason, draws one's attention to it, is represented by a larger number of specimens which, as a whole, are preserved in an excellent three-dimensional state. No considerable variations are shown by the ovaloidal theca which is slightly flattened down ventrally (a phenomenon which is expressed by a curvature of an only relatively smaller order of magnitude). The plates appear to be flat to slightly convex; their surfaces are ornamented, in varying degrees of densities, with angular to vermicularly curved, irregularly distributed, low tubercle-seams. The sutures are covered with low, more or less undular lists, constructed of closely spaced rows of tubercles which, on their part continue in form of closely spaced, short spines which, distally, thicken in knobular form. It is for this reason, that the optical median cross-section furnishes us with the image of an oval form framed with a dense seam made up of spines. On the apex we find a short protuberance which is as thin as a thread. The theca, with an epi-, and hypovalva of approximately the same size, shows the following arrangement and form of the tabulation. The apex region is made up of four apical plates, of which plate 1' (in direct extension of the longitudinal furrow) and plate 4' are elongated and show a ventral position. Plates 2' and 3' have a more thick-set form and lie on the dorsal side. These plates are followed by six pre-equatorial plates of trapezium-like contour (on the dorsal side) to trapezoidal contour (on the ventral side; of these pre-equatorial plates, plate 6 " is distinctly reduced. In the majority of the specimens, a pylome is present in the place of plate 3 ". The girdle furrow, which is not very much indented, has an average width of about 4 microns and is displaced distally about 1 times its own width; this girdle furrow is likewise bordered by low lists which are covered with tubercles and spines. A longitudinal furrow with distinct widening on the hypotheca and an intercalary lower plate, extends from the 1st. apical plate to the antapex. The hypotheca is made up of six post-equatorial plates, one accessory plate (1 p) and one polygonal, convex antapical plate. is again greatly reduced, plate 2" ' likewise does not as yet attain the normal size and has an approximately triangular shape. The color of the membrane varies from yellowish to brownish. Due to the dense sutural ornamentation and the formations superimposed on the seams, the envelope viewed as a whole appears somewhat darker.
Occurrence: Scherstetten l: Uncertain single discovery in sample no. S42b; presence assured, though occurring seldom, in samples nos. s39, s35, S33; in other words mainly distributed from Malm Upper-Alpha to Lower-Delta.
Dimensions: length/breadth-ratio | spines (length) | apex - protuberance
Holotype: 55 : 52 | 3 - 4 | 5 - 6 ( values also represent the minimum)
Paratypoids: 69: 63 | 4 | about 8
72 : 63 | 4 | 6 (values also represent the maximum)
Average: 66 : 61 | 4 | 6
Number of examined specimens: 49
Affinities: This species can be easily distinguished from the G. granulata and from the G. granuligera which have a shape resembling that of the species here in question; the distinction can be drawn on the basis that the G. aculeata n.sp. displays lists on its sutures which are more closely spaced and bear longer spines and, moreover, are more salient.
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Remark: [Courtinat, 1989, p. 200]: (Translation: LPP):
According to Stover (pers. com. in Lentin and Williams, 1985), the holotype possesses a 2P archaeopyle, which justifies the transfer to Occisucytsa by Below, 1981. Jan du Chêne et al., 1986 indicate that their observations do not allow the confirmation of that morphological characteristic; they retain this species in Acanthaulax. Some specimens from the Jura possess a 2P type archaeopyle; the most frequent type is that with a single precingular paraplate. For that reason aculeata is retained in Acanthaulax in the opinion that when a species exhibits several archaeopyle types it should be designated to the genus corresponding to the most frequently observed archaeopyle type.
NOW Tehamadinium. Originally Gonyaulax, subsequently Gonyaulacysta, thirdly Acanthaulax, fourthly Occisucysta, fifthly (and now) Tehamadinium.
Holotype: Klement, 1960, pl.5, figs.6-7.
Age: Early Kimmeridgian.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Gonyaulax aculeata: [Klement 1960, p. 42]:
Diagnosis:
A species of the genus Gonyaulax with the following tabulation scheme: 4', 6", 6 " ', 1p, 1 ppl, 1''''. Ovaloidal envelope, slightly flattened ventrally,with short apex protuberance which is as thin as a thread. Plates range from being flat to being slightly convex, in part, ornamented with vermicular, irregularly distributed, snort tubercle-sutures. Sutures are covered with low, tuberculated lists , bearing closely spaced, short spines which, distally, are thickened in a knobuar manner. Helicoidal transversal furrow, displaced distally by slightly more than 1 times its own width. (Transversal furrow width = about 4 microns). Longitudinal furrow widened on hypotheca, with intercalary lower plate.
Description:
This species, which shows a very characteristic type of development and, for this reason, draws one's attention to it, is represented by a larger number of specimens which, as a whole, are preserved in an excellent three-dimensional state. No considerable variations are shown by the ovaloidal theca which is slightly flattened down ventrally (a phenomenon which is expressed by a curvature of an only relatively smaller order of magnitude). The plates appear to be flat to slightly convex; their surfaces are ornamented, in varying degrees of densities, with angular to vermicularly curved, irregularly distributed, low tubercle-seams. The sutures are covered with low, more or less undular lists, constructed of closely spaced rows of tubercles which, on their part continue in form of closely spaced, short spines which, distally, thicken in knobular form. It is for this reason, that the optical median cross-section furnishes us with the image of an oval form framed with a dense seam made up of spines. On the apex we find a short protuberance which is as thin as a thread. The theca, with an epi-, and hypovalva of approximately the same size, shows the following arrangement and form of the tabulation. The apex region is made up of four apical plates, of which plate 1' (in direct extension of the longitudinal furrow) and plate 4' are elongated and show a ventral position. Plates 2' and 3' have a more thick-set form and lie on the dorsal side. These plates are followed by six pre-equatorial plates of trapezium-like contour (on the dorsal side) to trapezoidal contour (on the ventral side; of these pre-equatorial plates, plate 6 " is distinctly reduced. In the majority of the specimens, a pylome is present in the place of plate 3 ". The girdle furrow, which is not very much indented, has an average width of about 4 microns and is displaced distally about 1 times its own width; this girdle furrow is likewise bordered by low lists which are covered with tubercles and spines. A longitudinal furrow with distinct widening on the hypotheca and an intercalary lower plate, extends from the 1st. apical plate to the antapex. The hypotheca is made up of six post-equatorial plates, one accessory plate (1 p) and one polygonal, convex antapical plate. is again greatly reduced, plate 2" ' likewise does not as yet attain the normal size and has an approximately triangular shape. The color of the membrane varies from yellowish to brownish. Due to the dense sutural ornamentation and the formations superimposed on the seams, the envelope viewed as a whole appears somewhat darker.
Occurrence: Scherstetten l: Uncertain single discovery in sample no. S42b; presence assured, though occurring seldom, in samples nos. s39, s35, S33; in other words mainly distributed from Malm Upper-Alpha to Lower-Delta.
Dimensions: length/breadth-ratio | spines (length) | apex - protuberance
Holotype: 55 : 52 | 3 - 4 | 5 - 6 ( values also represent the minimum)
Paratypoids: 69: 63 | 4 | about 8
72 : 63 | 4 | 6 (values also represent the maximum)
Average: 66 : 61 | 4 | 6
Number of examined specimens: 49
Affinities: This species can be easily distinguished from the G. granulata and from the G. granuligera which have a shape resembling that of the species here in question; the distinction can be drawn on the basis that the G. aculeata n.sp. displays lists on its sutures which are more closely spaced and bear longer spines and, moreover, are more salient.
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Remark: [Courtinat, 1989, p. 200]: (Translation: LPP):
According to Stover (pers. com. in Lentin and Williams, 1985), the holotype possesses a 2P archaeopyle, which justifies the transfer to Occisucytsa by Below, 1981. Jan du Chêne et al., 1986 indicate that their observations do not allow the confirmation of that morphological characteristic; they retain this species in Acanthaulax. Some specimens from the Jura possess a 2P type archaeopyle; the most frequent type is that with a single precingular paraplate. For that reason aculeata is retained in Acanthaulax in the opinion that when a species exhibits several archaeopyle types it should be designated to the genus corresponding to the most frequently observed archaeopyle type.