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Tubotuberella eisenackii
Tubotuberella eisenackii (Deflandre, 1938) Stover and Evitt, 1978; Emendation: Sarjeant, 1982b, p.32–33, as Gonyaulacysta eisenackii.
Now Gonyaulacysta. Originally Gonyaulax, subsequently (and now) Gonyaulacysta, thirdly Endoscrinium, fourthly Tubotuberella. Jan du Chene et al., 1986 and Brenner, 1988 retained this species in Tubotuberella. Lentin and Williams, 1989 retain it in Gonyaulacysta Deflandre, 1964.
Taxonomic junior synonym: Tubotuberella sphaerocephalis, according to Sarjeant (1982b, p.32).
Holotype: Deflandre, 1938, pl.6, figs.7-8, text-figs.3-4; Jan du Chene et al., 1986, pl.125, figs.5-9
Locus typicus: Villers-sur-mer, Calvados, France
Stratum typicum: Oxfordian
Translation Deflandre, 1938: LPP
Original description: Deflandre 1938, p. 171-173: Gonyaulax eisenackii
In frontal view, this species looks rhomboidal, with a truncate lower pole. The transverse furrow is strongly helicoidal and the tw halves are clearly of equal size. The epiteca is conical and ends in a slightly truncate or bifid tip. The hypotheca is truncate and asymmetrical in lateral view resulting from the strong development of a sutural septum stemming from a postequatorial dorsal plate which forms a comb with five or six teeth. The sutures bear well-developed spinous or serrate septa, that show spines included in the membrane of the septum. At the junctions of the septa, more or less well-developed thorns are present. On the epitheca, these thorns are generally stronger on the upper corners between the first and second pre-equatorial plate and between the fourth and fifth pre-equatorial. On the hypotheca, this is always the case on the two distal corners of the fourth postequatorial. There are six pre-equatorial plates. the sixth is notably smaller and appears to be of variable shape (curved to trapezoidal (plate 6, figs.8 and 10). There seem to be 4 apical plates, but the two straight plates may be part of the longitudinal furrow. It is necessary to study the apical view. The hypotheca has six post-equatorial plates, the first of which is very small. Sometimes it is difficult to discern the tiny plates on the ventral side. The very small postequatorial plate is often found in Recent Gonyaulax. There is just one antapical plate and one posterior intercalary, bordering the first two post-equatorials. The tabulation of the hypotheca is very characteristic and resembles that of Recent Gonyaulax. The thecal membrane appears to be smooth, maybe very lightly punctate. Where verifiable, the third (dorsal) pre-equatorial plate was missing, like in G. jurassica. All specimens show straight sides, in only one specimen they are slightly concave. Some specimens appear to be shorter than the depicted ones. approximate dimensions: length 65-80 µm, breadth 57-60 µm.
Now Gonyaulacysta. Originally Gonyaulax, subsequently (and now) Gonyaulacysta, thirdly Endoscrinium, fourthly Tubotuberella. Jan du Chene et al., 1986 and Brenner, 1988 retained this species in Tubotuberella. Lentin and Williams, 1989 retain it in Gonyaulacysta Deflandre, 1964.
Taxonomic junior synonym: Tubotuberella sphaerocephalis, according to Sarjeant (1982b, p.32).
Holotype: Deflandre, 1938, pl.6, figs.7-8, text-figs.3-4; Jan du Chene et al., 1986, pl.125, figs.5-9
Locus typicus: Villers-sur-mer, Calvados, France
Stratum typicum: Oxfordian
Translation Deflandre, 1938: LPP
Original description: Deflandre 1938, p. 171-173: Gonyaulax eisenackii
In frontal view, this species looks rhomboidal, with a truncate lower pole. The transverse furrow is strongly helicoidal and the tw halves are clearly of equal size. The epiteca is conical and ends in a slightly truncate or bifid tip. The hypotheca is truncate and asymmetrical in lateral view resulting from the strong development of a sutural septum stemming from a postequatorial dorsal plate which forms a comb with five or six teeth. The sutures bear well-developed spinous or serrate septa, that show spines included in the membrane of the septum. At the junctions of the septa, more or less well-developed thorns are present. On the epitheca, these thorns are generally stronger on the upper corners between the first and second pre-equatorial plate and between the fourth and fifth pre-equatorial. On the hypotheca, this is always the case on the two distal corners of the fourth postequatorial. There are six pre-equatorial plates. the sixth is notably smaller and appears to be of variable shape (curved to trapezoidal (plate 6, figs.8 and 10). There seem to be 4 apical plates, but the two straight plates may be part of the longitudinal furrow. It is necessary to study the apical view. The hypotheca has six post-equatorial plates, the first of which is very small. Sometimes it is difficult to discern the tiny plates on the ventral side. The very small postequatorial plate is often found in Recent Gonyaulax. There is just one antapical plate and one posterior intercalary, bordering the first two post-equatorials. The tabulation of the hypotheca is very characteristic and resembles that of Recent Gonyaulax. The thecal membrane appears to be smooth, maybe very lightly punctate. Where verifiable, the third (dorsal) pre-equatorial plate was missing, like in G. jurassica. All specimens show straight sides, in only one specimen they are slightly concave. Some specimens appear to be shorter than the depicted ones. approximate dimensions: length 65-80 µm, breadth 57-60 µm.