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Tubotuberella dangeardii
From Fensome et al., 2019:
Tubotuberella dangeardii (Sarjeant, 1968, p.226–227, pl.1, fig.21; pl.3, figs.8,15; text-fig.3) Stover and Evitt, 1978, p.197.
Emendation: Sarjeant, 1982b, p.42–43, as Tubotuberella dangeardii.
Holotype: Sarjeant, 1968, pl.3, fig.8; text-fig.3; Sarjeant, 1982b, text-figs.5c–d; Jan du Chêne et al., 1986a, pl.127, figs.4–7; Fensome et al., 1993a, figs.1,3–4 — p.1089; figs.1,4–5 — p.1093.
Originally Gonyaulacysta, subsequently Dimidiadinium, thirdly (and now) Tubotuberella. Lentin and Williams (1985, p.150) retained this species in Tubotuberella.
Locus typicus: Falaise des Caches Noires, Villers-sur-Mer, (Calvados), France
Stratum typicum: Oxfordian
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Original description: Sarjeant, 1968, p. 226-227: Gonyaulacysta dangeardii
Diagnosis: A species of Gonyaulacysta having a theca of approximately pentagonal outline. The endophragm and periphragm are generally in contact, but the periphragm is detached in three places: at the apex, where it forms a short, blunt apical horn; along the line of the cingulum; and at the antapex, where an antapical pericoel is present. Tabulation 4", ?0a, 6"", ?6c, 6""", 1p, 1""""; sutures marked by low ridges which very occasionally bear minute spinelets. Cingulum narrow, strongly
laevo-rotatory: sulcus broader, extending onto the epitract.
Description: The roughly pentagonal outline results from the outbulge of the periphragm along the line of the cingulum. This divides the shell into an approximately hemispherical epitract (surmounted, and given angularity, by the apical horn) and a hypotract in the form of a truncated cone, the antapex being quite flat. The first apical plate is elongate and occupies the anterior prolongation of the sulcus: the three other plates are smaller. No anterior intercalary plate appears to be present; the six precingular plates are therefore of almost equal size, plate 3"" being typically lost in archaeopyle formation. Six postcingular plates were present, the first being reduced to accommodate an almost triangular posterior intercalary plate. The antapex is occupied by a single polygonal plate situated exactly at right angels to the long axis of the shell. The positions of the sutures subdividing it were difficult to determine, but six cingular plates are thought to be present. The sulcus, roughly twice as broad as the cingulum, lacks subdivisions. The relatively thin wall was frequently folded in some measure, enhancing the difficulty of determining the tabulation: in the holotype, folding of the hypotract obscured the position of the boundary between plates 1""" and 1p.
Dimensions: Holotype: overall length 70 µm, breadth 50 µm; length of apical horn 7 µm; length of antapical pericoel 12.5 µm, breadth of endophragm 45 µm. Range: overall length 70-89 µm, breadth 40-55 µm; length of apical horn 4-8 µm; length of antapical pericoel 9-14 µm; breadth of endophragm 38-53 µm.
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Emended diagnosis: Sarjeant 1982, p. 42-43
Cyst proximate, bicavate to almost circumcavate, approximately rhomboidal in outline but with one corner (the antapex) prolonged and truncate. A short apical horn or mamelon is present. The epipericoel may widen to form a sort of plinth beneath this horn, may taper smoothly into it or may be confined within the horn (cornucavate to acrocavate); in lateral view, it may sometimes be seen to extend some way down the flank of the epitract. In overall shape, the epitract is conical and smaller than the hypotract. The hypotract has the form of a truncated cone with slightly concave or inbent flanks, this inbending occurring at the position of separation of periphragm from endophragm. The hypopericoel occupies about one-third to two-fifths of the length of the hypotract; its breadth (measured at the level of the antapex of the endoblast) is greater than its length. The parasutures may be feebly marked by lines only, but more often give rise to low ridges from which arise short denticles, variably but most often widely spaced. In some specimens, these denticles form a pronounced fringe about the antapex. Paratabulation: 0-?2pa, 4", 0-"?2a, 6", 6c, 6"", lp, 0-lpv, 1"". Paraplate 6" shows some variation in size; it may be relatively large (almost as large as 5") to markedly reduced and triangular. Its boundary with 5" may be concave to convex, its boundary with the sulcus straight to slightly convex. The point of intersection of the boundary between 4" and 6" with the right lateral boundary of 1" varies in position, but it is always anterior to the junction of the latter paraplate with the sulcus. Antapex of periblast occupied by a large opisthopyle. Archaeopyle single-plate precingular, formed by loss of paraplate 3"; operculum reduced.
DISCUSSION: The species dangeardii, as here redefined, is placed into Tubotuberella rather than Gonyaulaeysta on the bases of its meagre parasutural ornamentation, inwardly flexured hypotractal ambitus and antapically positioned opisthopyle. Nevertheless, in its retention of denticulate crests (however meagrely developed), in its paratabulation pattern and relatively feebly developed hypopericoel, it represents an intermediate condition between those genera, leading on to such forms as T. apatela and T. egemenii. It differs from those species in the form of its pericoels and its retention of parasutural ornamentation.
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Supplemental diagnosis: Brideaux, 1977, p. 37-38: Dimidiadinium dangerardii
As for the genus with these particular features: short, blunt apical horn; hypopericyst tapering gently from latitude of pericingulum and then sharply to enclose a frustum-shaped antapical pericoel; endocyst ambitus ovoid; periphragm smooth with low, smooth or minutely spinate parasutural ridges defining a paratabulation of 4", ?0a, 6", 6""", 1p, 1""""; archeopyle formed by the loss of the third precingular paraplate; operculum trapezoidal in shape, simple and detached; pericingulum helicoid, displaced twice its breadth, perisulcus narrow anteriorly and extending well onto the epipericyst, broader posteriorly; antapical breach present or absent. Sarjeant (1968, p. 226) gives further details about the shape and disposition of the paraplates.
Affinities:
Brideaux, 1977, p. 38: Dimidiadinium dangerardii
The species differs from Dimidiadinium sphaerocephalum (Vozzhennikova) and Dimidiadinium uncinatum in possessing smooth or minutely spinate parasutures.
Tubotuberella dangeardii (Sarjeant, 1968, p.226–227, pl.1, fig.21; pl.3, figs.8,15; text-fig.3) Stover and Evitt, 1978, p.197.
Emendation: Sarjeant, 1982b, p.42–43, as Tubotuberella dangeardii.
Holotype: Sarjeant, 1968, pl.3, fig.8; text-fig.3; Sarjeant, 1982b, text-figs.5c–d; Jan du Chêne et al., 1986a, pl.127, figs.4–7; Fensome et al., 1993a, figs.1,3–4 — p.1089; figs.1,4–5 — p.1093.
Originally Gonyaulacysta, subsequently Dimidiadinium, thirdly (and now) Tubotuberella. Lentin and Williams (1985, p.150) retained this species in Tubotuberella.
Locus typicus: Falaise des Caches Noires, Villers-sur-Mer, (Calvados), France
Stratum typicum: Oxfordian
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Original description: Sarjeant, 1968, p. 226-227: Gonyaulacysta dangeardii
Diagnosis: A species of Gonyaulacysta having a theca of approximately pentagonal outline. The endophragm and periphragm are generally in contact, but the periphragm is detached in three places: at the apex, where it forms a short, blunt apical horn; along the line of the cingulum; and at the antapex, where an antapical pericoel is present. Tabulation 4", ?0a, 6"", ?6c, 6""", 1p, 1""""; sutures marked by low ridges which very occasionally bear minute spinelets. Cingulum narrow, strongly
laevo-rotatory: sulcus broader, extending onto the epitract.
Description: The roughly pentagonal outline results from the outbulge of the periphragm along the line of the cingulum. This divides the shell into an approximately hemispherical epitract (surmounted, and given angularity, by the apical horn) and a hypotract in the form of a truncated cone, the antapex being quite flat. The first apical plate is elongate and occupies the anterior prolongation of the sulcus: the three other plates are smaller. No anterior intercalary plate appears to be present; the six precingular plates are therefore of almost equal size, plate 3"" being typically lost in archaeopyle formation. Six postcingular plates were present, the first being reduced to accommodate an almost triangular posterior intercalary plate. The antapex is occupied by a single polygonal plate situated exactly at right angels to the long axis of the shell. The positions of the sutures subdividing it were difficult to determine, but six cingular plates are thought to be present. The sulcus, roughly twice as broad as the cingulum, lacks subdivisions. The relatively thin wall was frequently folded in some measure, enhancing the difficulty of determining the tabulation: in the holotype, folding of the hypotract obscured the position of the boundary between plates 1""" and 1p.
Dimensions: Holotype: overall length 70 µm, breadth 50 µm; length of apical horn 7 µm; length of antapical pericoel 12.5 µm, breadth of endophragm 45 µm. Range: overall length 70-89 µm, breadth 40-55 µm; length of apical horn 4-8 µm; length of antapical pericoel 9-14 µm; breadth of endophragm 38-53 µm.
---------------------------------------------
Emended diagnosis: Sarjeant 1982, p. 42-43
Cyst proximate, bicavate to almost circumcavate, approximately rhomboidal in outline but with one corner (the antapex) prolonged and truncate. A short apical horn or mamelon is present. The epipericoel may widen to form a sort of plinth beneath this horn, may taper smoothly into it or may be confined within the horn (cornucavate to acrocavate); in lateral view, it may sometimes be seen to extend some way down the flank of the epitract. In overall shape, the epitract is conical and smaller than the hypotract. The hypotract has the form of a truncated cone with slightly concave or inbent flanks, this inbending occurring at the position of separation of periphragm from endophragm. The hypopericoel occupies about one-third to two-fifths of the length of the hypotract; its breadth (measured at the level of the antapex of the endoblast) is greater than its length. The parasutures may be feebly marked by lines only, but more often give rise to low ridges from which arise short denticles, variably but most often widely spaced. In some specimens, these denticles form a pronounced fringe about the antapex. Paratabulation: 0-?2pa, 4", 0-"?2a, 6", 6c, 6"", lp, 0-lpv, 1"". Paraplate 6" shows some variation in size; it may be relatively large (almost as large as 5") to markedly reduced and triangular. Its boundary with 5" may be concave to convex, its boundary with the sulcus straight to slightly convex. The point of intersection of the boundary between 4" and 6" with the right lateral boundary of 1" varies in position, but it is always anterior to the junction of the latter paraplate with the sulcus. Antapex of periblast occupied by a large opisthopyle. Archaeopyle single-plate precingular, formed by loss of paraplate 3"; operculum reduced.
DISCUSSION: The species dangeardii, as here redefined, is placed into Tubotuberella rather than Gonyaulaeysta on the bases of its meagre parasutural ornamentation, inwardly flexured hypotractal ambitus and antapically positioned opisthopyle. Nevertheless, in its retention of denticulate crests (however meagrely developed), in its paratabulation pattern and relatively feebly developed hypopericoel, it represents an intermediate condition between those genera, leading on to such forms as T. apatela and T. egemenii. It differs from those species in the form of its pericoels and its retention of parasutural ornamentation.
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Supplemental diagnosis: Brideaux, 1977, p. 37-38: Dimidiadinium dangerardii
As for the genus with these particular features: short, blunt apical horn; hypopericyst tapering gently from latitude of pericingulum and then sharply to enclose a frustum-shaped antapical pericoel; endocyst ambitus ovoid; periphragm smooth with low, smooth or minutely spinate parasutural ridges defining a paratabulation of 4", ?0a, 6", 6""", 1p, 1""""; archeopyle formed by the loss of the third precingular paraplate; operculum trapezoidal in shape, simple and detached; pericingulum helicoid, displaced twice its breadth, perisulcus narrow anteriorly and extending well onto the epipericyst, broader posteriorly; antapical breach present or absent. Sarjeant (1968, p. 226) gives further details about the shape and disposition of the paraplates.
Affinities:
Brideaux, 1977, p. 38: Dimidiadinium dangerardii
The species differs from Dimidiadinium sphaerocephalum (Vozzhennikova) and Dimidiadinium uncinatum in possessing smooth or minutely spinate parasutures.