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Ctenidodinium
From Williams et al., 2017:
[Ctenidodinium Deflandre, 1939a, p. 181; Emendations: Sarjeant, 1966b, p.154; Gocht, 1970, p. 140; Sarjeant, 1975a, p. 55-56; Woollam, 1983, p. 190, 193; Benson, 1985, p. 150.
tax. sr. synonym of Dichadogonyaulax Sarjeant, 1966, according to Lentin and Williams, 1973, and Stover and Evitt, 1978. Sarjeant, 1975, Wolloam, 1983, and Benson, 1985, retained Dichadogonyaulax as a separate genus.
tax. sr. synonym of Korystocysta Woollam, 1983, according to Courtinat, 1989. Lentin and Williams, 1989, retained Korystocysta as a separate genus.
Type species: originally as Lithodinia jurassica var. ornata, Eisenack, 1935 (pl.4, fig.9)] ; Ctenidodinium ornatum, Deflandre, 1938
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Original description: [Deflandre, 1938]: (Translation Deflandre, 1938: Stover and Evitt, 1978, p. 203):
Diagnosis:
This new genus is characterized by the possession of strongly projecting ribs, ornamented with well- developed horns or spines, thus forming sort of small combs. These ribs delimit polygonal fields, constituting an apparently constant tabulation. Strictly speaking, there is no furrow, but the cell is divided into two separable valves by an equatorial girdle formed by a single rib. The type of the genus, Ctenidodinium ornatum, was described by A. Eisenack, who classified it provisionally as a variety of his dinoflagellate Lithodinia jurassica Eis. under the name of var. ornata. I have not been able so far to see the whole tabulation figured by Eisenack and which I adopt here. This hypotheca carries at the center a large quadrangular plate connected to the girdle by: (1) three large trapezoid plates which I have consistently found; (2) three small plates which constitute the "ventral" part and which I have not been able to see in any of my specimens. What I have observed leads me to characterize the genus Ctenidodinium by: (1) the presence of the single. pectinate equatorial rib attached to the hypotheca; (2) the narrow girdle which adheres to and follows it when the valves separate; (3) the system of plates of the hypotheca which I have described above.
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Emended descriptions:
Sarjeant, 1966:
Diagnosis:
Proximo-chorate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polygonal, having the tabulation 3-4`, 0-1a, 6``, 6c, 6```, 1p, 0-1 p.v., 1````; sutures in form of low ridges bearing crests of varied form, typically but not constantly high and denticulate.
Cingulum strongly or weakly spiral, laevorotatory; suture on anterior margin of cingulum lacking crest, crest on posterior margin very high.
Archaeopyle (where present) formed by schism along cingulum.
-----------------------------------
Gocht, 1970: (Translation: LPP):
Diagnosis:
(after Sarjeant, 1966, slightly altered): Proximo-chorate dinoflagellate cyst, spherical, ellipsoidal or polygonal. Tabulation 3-4`, 1-3a, 6``, 6c, 6```, 1p, 0-1 p.v., 1````. Low sutural ribs, with or without wall-edges of varying form, mostly quite high and denticulate. Girdle more or less spiral, laevorotatory. Sutures of the anterior girdle margin often without wall-edges.
Archaeopyle formation by preformed schism along the anterior girdle margin.
-----------------------------------
Sarjeant, 1975:
Diagnosis:
Proximate to proximochorate dinoflagellate cysts, spheroidal to ovoidal, ellipsoidal or subpolygonal in shape, with or (typically) without an apical horn but always without median or antapical horns. Reflected tabulation 3-6`, 0-3a, 6`` , 6c, 5-6```, 0-1p, 0-1pv, 1````, plus a variable number of sulcal plate-areas occupying the ventral surface. Cingulum strongly or weakly helicoid, laevorotatory. Boundaries between plate-areas marked by low ridges, with or without raised crests of varied form or lines of processes. Sutural development on the boundaries of the cingulum strongly asymmetrical, the crests or processes on the posterior boundary being much higher than those on the anterior boundary. Sutural development elsewhere on the cyst variable, but in general the crests or processes on the hypotract tend to be more consistently high than those on the epitract.
Archaeopyle (where developed) epitractal, formed by schism along the centre or the anterior margin of the cingulum; the resultant hemicysts, in particular the epitract, may break up by further schism along plate-area boundaries.
(rejected by Stover and Evitt, 1978, p. 203)
Affinities:
In my view, the highly asymmetric development of the cingular boundaries in Ctenidodinium ornatum and related species is a sufficiently distinctive feature to merit generic differentiation. The hemicysts, in particular the hypotracts, are highly distinctive constituents of Jurassic assemblages from Bathonian to lowest Kimmeridgian and are important stratigraphical indices. (It is already clear that the forms of simpler morphology, here placed in Dichadogonyaulax, have a much longer stratigraphical range, appearing probably in the Bajocian and ranging up into the Lower Cretaceous).
-----------------------------------
Woollam, 1983:
Diagnosis:
Cysts proximochorate, autophragm only. Body subspherical to ellipsoidal, generally without an apical horn. Paratabulation gonyaulacoid, 0-3pa, 4`, 0-2a, 6``, 6c, x-6s, 6```, 1p, 1````, indicated by parasutural rows of isolated or proximally linked processes or by parasutural crests or septa, generally denticulate to spinate. Crest development on the paracingulum strongly asymmetrical, the posterior paracingular crest being much higher than the anterior paracingular crest. Crest development elsewhere on the cyst variable, but in general consistently higher on the hypocyst than the epicyst. Archaeopyle epicystal, formed by schism along a line anterior to the paracingulum, initiated dorsally, operculum (epicyst) attached ventrally at the parasulcus.
Affinities:
Ctenidodinium differs from Dichadogonyaulax primarily in the asymmetry of the paracingular crests, the posterior being higher than the anterior, whereas in Dichadogonyaulax they are symmetrically developed.
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Benson, 1985:
Description:
Proximochorate dinoflagellate cysts constructed of an autophragm, subspherical to ellipsoidal in shape, lacking an apical horn.
Paratabulation formula: 1-3pr, 4`,1-2a, 6``, x-6c, 6```, 1p, 1````, x-6s, indicated by parasutural ridges, crests or septa which are generally ornamented with spines. Accessory ridges ("growth bands") generally absent. Combination (epicystal, tprtAtltP, henceforth referred to as Type E) archeopyle, operculum separating from the hypocyst along the posterior margin of the precingular paraplates.
Parasutural features on the paracingulum may or may not be reduced on the anterior margin as compared with the posterior margin.
Affinities:
Ctenidodinium differs from Dichadogonyaulax in possessing one or more preapical paraplates positioned at the apex and anterior intercalary paraplates, from Korystocysta in generally lacking accessory parasutural ridges (although see Gocht, 1984, and Pl. 2, fig. 4) and an apical horn, and from Energlynia in lacking an antapical horn and having an epicyst and hypocyst of nearly equal size.
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Modified descriptions:
Stover and Evitt 1978, p. 203-204:
Synopsis:
Cysts proximochorate; body subspherical to ellipsoidal; paratabulation gonyaulacacean, indicated by parasutural rows of isolated or proximally linked projections or by parasutural ridges or septa, generally with denticulate to spinate crests; combination epicystal archeopyle, Type tAtP.
Description:
Shape: Body subspherical to ellipsoidal; separated epicysts and hypocysts commonly seen in polar views.
Wall relationships: Autophragm only.
Wall features: Parasutural features include rows of projections, either isolated or joined proximally, and/or smooth ridges or septa, generally with denticulate to spinate crests. Surface between parasutural features smooth or has features of low relief.
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 0-1pr, 4`, 0-3a, 6``, Xc-6c, 5-6```,1p, 1````, 0-5s.
Archeopyle: Combination, epicystal, Type tAtP; operculum possibly attached, but more commonly separated; principal archeopyle suture immediately apical to paracingulum.
Paracingulum: Indicated by six rectangular paraplates or by parallel equatorial transverse ridges, septa, or rows of projections. Anterior parasutural features may be less well developed than posterior ones.
Parasulcus: Usually discernible on hypocyst.
Size: Small to intermediate.
Affinities:
Ctenidodinium differs from Luehndea in lacking large dorsal intercalary paraplates and in having parasutural spines not limited to gonal positions. Energlynia differs from Ctenidodinium in having an apical horn and in either lacking parasutural features or having less well-developed ones.
Separation of Dichadogonyaulax and Ctenidodinium, according to Sarjeant, 1966,1975, is based on the equal development of features marking the apical and antapical limits of the paracingulum in the former genus in contrast to their unequal development in the latter. Gocht`s 1970 description for Ctenidodinium accounts for this difference, and we concur with the action taken by Lentin & Williams, 1973, who considered Dichadogonyaulax a junior synonym of Ctenidodinium.
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Courtinant, 1989, p. 208: (Translation: LPP):
Remarks:
Sarjeant (1966) and Woollam (1983) created the genera Dichadogonyaulax and Korystocysta, which differ from Ctenidodinium respectively in the symmetry of the adcingular septa and in details of the ventral paratabulation as well as in the presence of accessory sutural septa. The genus Korystocysta is not retained and is considered a junior synonym of Ctenidodinium. The elements which permita differentiation of Ctenidodinium and Dichadogonyaulax are a Q/B apical or a gamma dorsal precingular paratabulation in Ctenidodinium, and an A/B apical or type psi dorsal precingular paratabulation in Dichadogonyaulax. The gamma dorsal precingular paratabulation is defined for forms where the limit between apical paraplates B and C corresponds to the the middle of precingular paraplate 4, whilst the in type psi, this boundary is in line with the boundary between precingular paraplates 4 and 5. The presence of accessory suturtal septa, the presence or absence of an apical horn and the presence or absence of anterior intercalary paraplates are characteristics considered exclusively species-related. For this reason, the distinctions of Benson (in Jan du Ch`eane et al., 1985) are not retained.
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Ctenidodinium Deflandre, 1939a, emend. Sarjeant, 1975a, emend. Benson, 1985. Originally (e.g. Sarjeant, 1975a) Ctenidodinium was differentiated from Dichadogonyaulax on the unequal development of the cingular crests. Benson (1985) said the two genera differed in that Ctenidodinium had one or two more preapical plates and anterior intercalary plates and in Dichadogonyaulax the off-centre preapical structure allows contact of the 2` and 4` plates; and both differed from Korystocysta in generally lacking accessory parasutural ridges and an apical horn. Benson (1985) gave the tabulation as 1-3pr, 4`, 1-2a, 6", x-6c, 6"`, 1p, 1"", 1-6s.
[Ctenidodinium Deflandre, 1939a, p. 181; Emendations: Sarjeant, 1966b, p.154; Gocht, 1970, p. 140; Sarjeant, 1975a, p. 55-56; Woollam, 1983, p. 190, 193; Benson, 1985, p. 150.
tax. sr. synonym of Dichadogonyaulax Sarjeant, 1966, according to Lentin and Williams, 1973, and Stover and Evitt, 1978. Sarjeant, 1975, Wolloam, 1983, and Benson, 1985, retained Dichadogonyaulax as a separate genus.
tax. sr. synonym of Korystocysta Woollam, 1983, according to Courtinat, 1989. Lentin and Williams, 1989, retained Korystocysta as a separate genus.
Type species: originally as Lithodinia jurassica var. ornata, Eisenack, 1935 (pl.4, fig.9)] ; Ctenidodinium ornatum, Deflandre, 1938
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Deflandre, 1938]: (Translation Deflandre, 1938: Stover and Evitt, 1978, p. 203):
Diagnosis:
This new genus is characterized by the possession of strongly projecting ribs, ornamented with well- developed horns or spines, thus forming sort of small combs. These ribs delimit polygonal fields, constituting an apparently constant tabulation. Strictly speaking, there is no furrow, but the cell is divided into two separable valves by an equatorial girdle formed by a single rib. The type of the genus, Ctenidodinium ornatum, was described by A. Eisenack, who classified it provisionally as a variety of his dinoflagellate Lithodinia jurassica Eis. under the name of var. ornata. I have not been able so far to see the whole tabulation figured by Eisenack and which I adopt here. This hypotheca carries at the center a large quadrangular plate connected to the girdle by: (1) three large trapezoid plates which I have consistently found; (2) three small plates which constitute the "ventral" part and which I have not been able to see in any of my specimens. What I have observed leads me to characterize the genus Ctenidodinium by: (1) the presence of the single. pectinate equatorial rib attached to the hypotheca; (2) the narrow girdle which adheres to and follows it when the valves separate; (3) the system of plates of the hypotheca which I have described above.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended descriptions:
Sarjeant, 1966:
Diagnosis:
Proximo-chorate dinoflagellate cysts, spheroidal, ovoidal, ellipsoidal or polygonal, having the tabulation 3-4`, 0-1a, 6``, 6c, 6```, 1p, 0-1 p.v., 1````; sutures in form of low ridges bearing crests of varied form, typically but not constantly high and denticulate.
Cingulum strongly or weakly spiral, laevorotatory; suture on anterior margin of cingulum lacking crest, crest on posterior margin very high.
Archaeopyle (where present) formed by schism along cingulum.
-----------------------------------
Gocht, 1970: (Translation: LPP):
Diagnosis:
(after Sarjeant, 1966, slightly altered): Proximo-chorate dinoflagellate cyst, spherical, ellipsoidal or polygonal. Tabulation 3-4`, 1-3a, 6``, 6c, 6```, 1p, 0-1 p.v., 1````. Low sutural ribs, with or without wall-edges of varying form, mostly quite high and denticulate. Girdle more or less spiral, laevorotatory. Sutures of the anterior girdle margin often without wall-edges.
Archaeopyle formation by preformed schism along the anterior girdle margin.
-----------------------------------
Sarjeant, 1975:
Diagnosis:
Proximate to proximochorate dinoflagellate cysts, spheroidal to ovoidal, ellipsoidal or subpolygonal in shape, with or (typically) without an apical horn but always without median or antapical horns. Reflected tabulation 3-6`, 0-3a, 6`` , 6c, 5-6```, 0-1p, 0-1pv, 1````, plus a variable number of sulcal plate-areas occupying the ventral surface. Cingulum strongly or weakly helicoid, laevorotatory. Boundaries between plate-areas marked by low ridges, with or without raised crests of varied form or lines of processes. Sutural development on the boundaries of the cingulum strongly asymmetrical, the crests or processes on the posterior boundary being much higher than those on the anterior boundary. Sutural development elsewhere on the cyst variable, but in general the crests or processes on the hypotract tend to be more consistently high than those on the epitract.
Archaeopyle (where developed) epitractal, formed by schism along the centre or the anterior margin of the cingulum; the resultant hemicysts, in particular the epitract, may break up by further schism along plate-area boundaries.
(rejected by Stover and Evitt, 1978, p. 203)
Affinities:
In my view, the highly asymmetric development of the cingular boundaries in Ctenidodinium ornatum and related species is a sufficiently distinctive feature to merit generic differentiation. The hemicysts, in particular the hypotracts, are highly distinctive constituents of Jurassic assemblages from Bathonian to lowest Kimmeridgian and are important stratigraphical indices. (It is already clear that the forms of simpler morphology, here placed in Dichadogonyaulax, have a much longer stratigraphical range, appearing probably in the Bajocian and ranging up into the Lower Cretaceous).
-----------------------------------
Woollam, 1983:
Diagnosis:
Cysts proximochorate, autophragm only. Body subspherical to ellipsoidal, generally without an apical horn. Paratabulation gonyaulacoid, 0-3pa, 4`, 0-2a, 6``, 6c, x-6s, 6```, 1p, 1````, indicated by parasutural rows of isolated or proximally linked processes or by parasutural crests or septa, generally denticulate to spinate. Crest development on the paracingulum strongly asymmetrical, the posterior paracingular crest being much higher than the anterior paracingular crest. Crest development elsewhere on the cyst variable, but in general consistently higher on the hypocyst than the epicyst. Archaeopyle epicystal, formed by schism along a line anterior to the paracingulum, initiated dorsally, operculum (epicyst) attached ventrally at the parasulcus.
Affinities:
Ctenidodinium differs from Dichadogonyaulax primarily in the asymmetry of the paracingular crests, the posterior being higher than the anterior, whereas in Dichadogonyaulax they are symmetrically developed.
-----------------------------------
Benson, 1985:
Description:
Proximochorate dinoflagellate cysts constructed of an autophragm, subspherical to ellipsoidal in shape, lacking an apical horn.
Paratabulation formula: 1-3pr, 4`,1-2a, 6``, x-6c, 6```, 1p, 1````, x-6s, indicated by parasutural ridges, crests or septa which are generally ornamented with spines. Accessory ridges ("growth bands") generally absent. Combination (epicystal, tprtAtltP, henceforth referred to as Type E) archeopyle, operculum separating from the hypocyst along the posterior margin of the precingular paraplates.
Parasutural features on the paracingulum may or may not be reduced on the anterior margin as compared with the posterior margin.
Affinities:
Ctenidodinium differs from Dichadogonyaulax in possessing one or more preapical paraplates positioned at the apex and anterior intercalary paraplates, from Korystocysta in generally lacking accessory parasutural ridges (although see Gocht, 1984, and Pl. 2, fig. 4) and an apical horn, and from Energlynia in lacking an antapical horn and having an epicyst and hypocyst of nearly equal size.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified descriptions:
Stover and Evitt 1978, p. 203-204:
Synopsis:
Cysts proximochorate; body subspherical to ellipsoidal; paratabulation gonyaulacacean, indicated by parasutural rows of isolated or proximally linked projections or by parasutural ridges or septa, generally with denticulate to spinate crests; combination epicystal archeopyle, Type tAtP.
Description:
Shape: Body subspherical to ellipsoidal; separated epicysts and hypocysts commonly seen in polar views.
Wall relationships: Autophragm only.
Wall features: Parasutural features include rows of projections, either isolated or joined proximally, and/or smooth ridges or septa, generally with denticulate to spinate crests. Surface between parasutural features smooth or has features of low relief.
Paratabulation: Indicated by parasutural features; gonyaulacacean, formula: 0-1pr, 4`, 0-3a, 6``, Xc-6c, 5-6```,1p, 1````, 0-5s.
Archeopyle: Combination, epicystal, Type tAtP; operculum possibly attached, but more commonly separated; principal archeopyle suture immediately apical to paracingulum.
Paracingulum: Indicated by six rectangular paraplates or by parallel equatorial transverse ridges, septa, or rows of projections. Anterior parasutural features may be less well developed than posterior ones.
Parasulcus: Usually discernible on hypocyst.
Size: Small to intermediate.
Affinities:
Ctenidodinium differs from Luehndea in lacking large dorsal intercalary paraplates and in having parasutural spines not limited to gonal positions. Energlynia differs from Ctenidodinium in having an apical horn and in either lacking parasutural features or having less well-developed ones.
Separation of Dichadogonyaulax and Ctenidodinium, according to Sarjeant, 1966,1975, is based on the equal development of features marking the apical and antapical limits of the paracingulum in the former genus in contrast to their unequal development in the latter. Gocht`s 1970 description for Ctenidodinium accounts for this difference, and we concur with the action taken by Lentin & Williams, 1973, who considered Dichadogonyaulax a junior synonym of Ctenidodinium.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Courtinant, 1989, p. 208: (Translation: LPP):
Remarks:
Sarjeant (1966) and Woollam (1983) created the genera Dichadogonyaulax and Korystocysta, which differ from Ctenidodinium respectively in the symmetry of the adcingular septa and in details of the ventral paratabulation as well as in the presence of accessory sutural septa. The genus Korystocysta is not retained and is considered a junior synonym of Ctenidodinium. The elements which permita differentiation of Ctenidodinium and Dichadogonyaulax are a Q/B apical or a gamma dorsal precingular paratabulation in Ctenidodinium, and an A/B apical or type psi dorsal precingular paratabulation in Dichadogonyaulax. The gamma dorsal precingular paratabulation is defined for forms where the limit between apical paraplates B and C corresponds to the the middle of precingular paraplate 4, whilst the in type psi, this boundary is in line with the boundary between precingular paraplates 4 and 5. The presence of accessory suturtal septa, the presence or absence of an apical horn and the presence or absence of anterior intercalary paraplates are characteristics considered exclusively species-related. For this reason, the distinctions of Benson (in Jan du Ch`eane et al., 1985) are not retained.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Ctenidodinium Deflandre, 1939a, emend. Sarjeant, 1975a, emend. Benson, 1985. Originally (e.g. Sarjeant, 1975a) Ctenidodinium was differentiated from Dichadogonyaulax on the unequal development of the cingular crests. Benson (1985) said the two genera differed in that Ctenidodinium had one or two more preapical plates and anterior intercalary plates and in Dichadogonyaulax the off-centre preapical structure allows contact of the 2` and 4` plates; and both differed from Korystocysta in generally lacking accessory parasutural ridges and an apical horn. Benson (1985) gave the tabulation as 1-3pr, 4`, 1-2a, 6", x-6c, 6"`, 1p, 1"", 1-6s.