Back
Leptodinium egemenii
Leptodinium egemenii Gitmez, 1970
Now Tubotuberella. Originally Leptodinium, subsequently (and now) Tubotuberella.
Questionable tax. jr. synonym of Tubotuberella sphaerocephalis Vozzhennikova, 1967, according to Brenner, 1988, who in the same publication listed Tubotuberella sphaerocephalis as a tax. jr. synonym of Tubotuberella (now Gonyaulacysta) eisenackii (Deflandre, 1938) Stover and Evitt, 1978. Because of the uncertainty concerning Brenner"s intentions, Lentin and Williams, 1993, retained Leptodinium (as Tubotuberella) egemenii as a separate species.
Holotype: Gitmez, 1970, pl.10, figs.5-6, text-fig.18; Jan du Chêne et al. 1986, pl.126, figs.4-7
Locus typicus: Osmington Mills, Dorset, England
Stratum typicum: Early Kimmeridgian
Original diagnosis: Gitmez, 1970, p.272
Leptodinium with proximate cyst polygonal in outline; with the reflected tabulation 4", 6", 6c, 6""", 2p and 1"""". Processes and apical horn lacking. Cingulum slightly spiral, sulcus approximately spindle-shaped. Endophragm and periphragm are in contact except at the apex and antapex: a pronounced antapical pericoel is present, but the degree of separation at the apex is small. Surface of the shell smooth. Precingular archaeopyle formed by loss of plate 3".
Dimensions: Holotype: overall length 70 Ám, breadth 58 Ám, shell length 54 Ám, breadth 58 Ám. Range of the English specimens (10 specimens measured): length 50(42)80 (57) Ám, breadth 40-50 Ám; French specimens (IO specimens measured): length 55 (35)78 (50) Ám, breadth 43-52 Ám; Scottish specimen: length 65 (45) Ám, breadth 48 Ám (1 specimen measured). [The length of the endoblast is shown in parenthesis.]
Original description: Gitmez, 1970, p.272-273
The thin-walled polygonal theca is divided into an approximately hemispherical epitract and a hypotract in the form of a truncated cone, the antapex being quite flat.
The first apical plate (1") is elongate, situated in the anterior prolongation of the sulcus; the three other apical plates are more or less uniform in size and smaller than plate 1". Six precingular plates, without any intercalary plate, together with the apical plates occupy the epitract. Plates 1" and 2" are larger than the others; plate 3" lost to form the precingular archaeopyle; plates 4" and 5" are elongate, 6" is approximately triangular in shape.
Six postcingular plates are present: the first (plate 1""") is small and more or less tetragonal; 2""" is narrow and elongate, plate 3""" is also elongate. Plate 4""" is largest of the postcingular plates. Plate 5""" is large and P-shaped as a result of the presence of the posterior intercalary plate 2p. Plate 6""" is smaller of the postcingular plates and triangular-shaped. One of the two posterior intercalary plates, 1p, is elongate and long; because of its accommodation, plate 1""" is reduced. Plate 2p is small and placed posterior to plates 5""" and 6""". The single antapical plate 1"""" is very small and flattened.
The sutures are poorly marked by low crests, their distal edge is always smooth.
Affinities:
Gitmez, 1970, p.273: L. egemanii is characterized by its tabulation, lack of an apical horn and presence of an antapical pericoel. The tabulation was difficult to determine because the crests were poorly marked, and the preservation generally not good. It was observed in the Dorset, Scottish and Le Havre assemblages in moderate abundance.
Although it has a Gonyaulacysta-type tabulation, it is not a species of Gonyaulacysta because of the absence of an apical horn, according to the emended diagnoses of Gonyaulacysta and Leptodinium (Sarjeant, 1969); it is therefore attributed to the genus Leptodinium.
This new species of Leptodinium compares with the species of the genus Psaligonyaulax and Tubotuberella, since it has a pronounced antapical pericoel. In the lack of apical horn and in the detail of the tabulation, it differs from Psaligonyaulax. Because Vozzhennikova was unable to give the tabulation of the genus Tubotuberella, it is impossible to be certain regarding the generic assignation for this new species.
Now Tubotuberella. Originally Leptodinium, subsequently (and now) Tubotuberella.
Questionable tax. jr. synonym of Tubotuberella sphaerocephalis Vozzhennikova, 1967, according to Brenner, 1988, who in the same publication listed Tubotuberella sphaerocephalis as a tax. jr. synonym of Tubotuberella (now Gonyaulacysta) eisenackii (Deflandre, 1938) Stover and Evitt, 1978. Because of the uncertainty concerning Brenner"s intentions, Lentin and Williams, 1993, retained Leptodinium (as Tubotuberella) egemenii as a separate species.
Holotype: Gitmez, 1970, pl.10, figs.5-6, text-fig.18; Jan du Chêne et al. 1986, pl.126, figs.4-7
Locus typicus: Osmington Mills, Dorset, England
Stratum typicum: Early Kimmeridgian
Original diagnosis: Gitmez, 1970, p.272
Leptodinium with proximate cyst polygonal in outline; with the reflected tabulation 4", 6", 6c, 6""", 2p and 1"""". Processes and apical horn lacking. Cingulum slightly spiral, sulcus approximately spindle-shaped. Endophragm and periphragm are in contact except at the apex and antapex: a pronounced antapical pericoel is present, but the degree of separation at the apex is small. Surface of the shell smooth. Precingular archaeopyle formed by loss of plate 3".
Dimensions: Holotype: overall length 70 Ám, breadth 58 Ám, shell length 54 Ám, breadth 58 Ám. Range of the English specimens (10 specimens measured): length 50(42)80 (57) Ám, breadth 40-50 Ám; French specimens (IO specimens measured): length 55 (35)78 (50) Ám, breadth 43-52 Ám; Scottish specimen: length 65 (45) Ám, breadth 48 Ám (1 specimen measured). [The length of the endoblast is shown in parenthesis.]
Original description: Gitmez, 1970, p.272-273
The thin-walled polygonal theca is divided into an approximately hemispherical epitract and a hypotract in the form of a truncated cone, the antapex being quite flat.
The first apical plate (1") is elongate, situated in the anterior prolongation of the sulcus; the three other apical plates are more or less uniform in size and smaller than plate 1". Six precingular plates, without any intercalary plate, together with the apical plates occupy the epitract. Plates 1" and 2" are larger than the others; plate 3" lost to form the precingular archaeopyle; plates 4" and 5" are elongate, 6" is approximately triangular in shape.
Six postcingular plates are present: the first (plate 1""") is small and more or less tetragonal; 2""" is narrow and elongate, plate 3""" is also elongate. Plate 4""" is largest of the postcingular plates. Plate 5""" is large and P-shaped as a result of the presence of the posterior intercalary plate 2p. Plate 6""" is smaller of the postcingular plates and triangular-shaped. One of the two posterior intercalary plates, 1p, is elongate and long; because of its accommodation, plate 1""" is reduced. Plate 2p is small and placed posterior to plates 5""" and 6""". The single antapical plate 1"""" is very small and flattened.
The sutures are poorly marked by low crests, their distal edge is always smooth.
Affinities:
Gitmez, 1970, p.273: L. egemanii is characterized by its tabulation, lack of an apical horn and presence of an antapical pericoel. The tabulation was difficult to determine because the crests were poorly marked, and the preservation generally not good. It was observed in the Dorset, Scottish and Le Havre assemblages in moderate abundance.
Although it has a Gonyaulacysta-type tabulation, it is not a species of Gonyaulacysta because of the absence of an apical horn, according to the emended diagnoses of Gonyaulacysta and Leptodinium (Sarjeant, 1969); it is therefore attributed to the genus Leptodinium.
This new species of Leptodinium compares with the species of the genus Psaligonyaulax and Tubotuberella, since it has a pronounced antapical pericoel. In the lack of apical horn and in the detail of the tabulation, it differs from Psaligonyaulax. Because Vozzhennikova was unable to give the tabulation of the genus Tubotuberella, it is impossible to be certain regarding the generic assignation for this new species.