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Tubotuberella egemenii
From Fensome et al., 2019:
Tubotuberella egemenii (Gitmez, 1970, p.272–274, pl.10, figs.5–6; text-fig.18) Stover and Evitt, 1978, p.197.
Holotype: Gitmez, 1970, pl.10, figs.5–6; text-fig.18; Jan du Chêne et al., 1986a, pl.126, figs.4–7.
Originally Leptodinium, subsequently (and now) Tubotuberella. Brenner (1988, p.93) considered Tubotuberella sphaerocephalis to be the questionable taxonomic senior synonym of this species.
Locus typicus: Shaly clay from the Liostrea delta Bed, Osmington Mills, Dorset, England
Stratum typicum: Early Kimmeridgian
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Original diagnosis: Gitmez, 1970, p.272: Leptodinium egemenii
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 µm, breadth 58 µm, shell length 54 µm, breadth 58 µm. Range of the English specimens (10 specimens measured): length 50(42)80 (57) µm, breadth 40-50 µm; French specimens (10 specimens measured): length 55 (35)78 (50) µm, breadth 43-52 µm; Scottish specimen: length 65 (45) µm, breadth 48 µm (1 specimen measured). [The length of the endoblast is shown in parenthesis.]
Original description: Gitmez, 1970, p.272-273: Leptodinium egemenii
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: Leptodinium egemenii
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.
Tubotuberella egemenii (Gitmez, 1970, p.272–274, pl.10, figs.5–6; text-fig.18) Stover and Evitt, 1978, p.197.
Holotype: Gitmez, 1970, pl.10, figs.5–6; text-fig.18; Jan du Chêne et al., 1986a, pl.126, figs.4–7.
Originally Leptodinium, subsequently (and now) Tubotuberella. Brenner (1988, p.93) considered Tubotuberella sphaerocephalis to be the questionable taxonomic senior synonym of this species.
Locus typicus: Shaly clay from the Liostrea delta Bed, Osmington Mills, Dorset, England
Stratum typicum: Early Kimmeridgian
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Original diagnosis: Gitmez, 1970, p.272: Leptodinium egemenii
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 µm, breadth 58 µm, shell length 54 µm, breadth 58 µm. Range of the English specimens (10 specimens measured): length 50(42)80 (57) µm, breadth 40-50 µm; French specimens (10 specimens measured): length 55 (35)78 (50) µm, breadth 43-52 µm; Scottish specimen: length 65 (45) µm, breadth 48 µm (1 specimen measured). [The length of the endoblast is shown in parenthesis.]
Original description: Gitmez, 1970, p.272-273: Leptodinium egemenii
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: Leptodinium egemenii
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.