Back
Dingodinium
From Williams et al., 2017:
[Dingodinium, Cookson and Eisenack, 1958, p. 39; Emendations: Mehrota and Sarjeant, 1984b, p. 295, Stover and Helby, 1987d, p.281 as a revised description
Type species: Dingodinium jurassicum, Cookson and Eisenack, 1958 (pl.1, fig.10)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Cookson and Eisenack, 1958]:
Description:
Theca consisting of a smooth, thin, transparent membrane without plates and a spherical to elongate-oval eccentrically placed capsule either covered with numerous small spines or smooth. A helicoid transverse furrow bounded on either side by a more or less distinct fold is always present on the outer membrane.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 229:
Synopsis:
Cysts camocavate, compressed ellipsoidal (flattened laterally), with or without an apical horn; endophragm and periphragm appressed dorsally, separated elsewhere; archeopyle type uncertain, possibly intercalary or combination.
Description:
Shape: Compressed ellipsoidal (flattened laterally), with or without an apical horn; outline of dorsal surface convex to obtusely angular.
Wall relationships: Cysts camocavate; endocyst ellipsoidal, or nearly so, appressed to pericyst dorsally, and separated elsewhere; resulting pericoel usually prominent.
Wall features: No parasutural features. Endophragm thicker than periphragm, smooth or variously ornamented with features of low to moderate relief, which generally do not reach the normally smooth, thinner periphragm.
Paratabulation: Indicated by paracingulum only.
Archeopyle: Type uncertain, possibly intercalary or combination (Type AI). Vague tears in periphragm between paracingulum and base of horn suggest that the archeopyle may be intercalary; however, specimens in which the apical horn is partially detached (adherent ventrally) or completely so suggest that the archeopyle may involve the apical part of the cyst as well as an additional paraplate.
Paracingulum: Usually expressed by parallel transverse folds in the periphragm; may be indicated only faintly.
Parasulcus: Rarely discernible because of lateral flattening; apparently expressed by a few weakly developed longitudinal folds on the hypocyst. Size: Intermediate to large.
Affinities:
Dingodinium and Polygonifera are similar in that each is camocavate; however, the archeopyle type in Polygonifera is apical; and it is uncertain in Dingodinium. Gardodinium differs from Dingodinium in being holocavate, with processes between endophragm and ectophragm, and in having an apical archeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Mehrota and Sarjeant, 1984:
Diagnosis:
Camocavate dinoflagellate cysts of intermediate to large size. Endoblast ellipsoidal to oval, appressed to periblast on one side (probably dorsal), with a pericoel developed on all other sides. Epipericoel commonly prolonged into an apical horn of variable relative length. Sometimes the periblast and endoblast may show interconnection in the antapical region. Endophragm thicker than periphragm. Endophragm smooth or variously ornamented with features of low to moderate relief; periphragm relatively much thinner, usually smooth, sometimes faintly ornamented with features of very low relief, never projecting out at cyst margin. Parasutural features generally not observed but sometimes indicated on periblast by faint to clearly marked lines, ridges or folds. Cingulum faintly to clearly indicated by transverse folds on periblast; sulcus indicated feebly by longitudinal folds. Paratabulation 2pr, 3-4`, 1-?3a, 0 or 5-6c, 6``, 6```, 1-2p, 1````.
Archeopyle not always distinct, either because it has not developed or because the endoperculum and perioperculum have remained attached and closed again after excystment. Where observable, it is of variable character.
Peripyle consisting always of all apical paraplates; perioperculum simple, usually remaining attached along its ventral surface and closing after excystment. Endopyle either of intercalary (1a or 2a) or of combination apical/intercalary or intercalary/precingular type. Combination archeopyle may involve either an intercalary paraplate (1a or 2a) and all apical paraplates or one intercalary (1a or 2a) and one precingular (3``) paraplate. Endoperculum simple or compound, free or partially or completely attached. Tip of apical horn, comprising the two small paraplates of the preapical series, frequently lost.
Archeopyle formula: The variations of the archeopyle in Dingodinium are presented below in the form of the archeopyle formulae of Evitt (1967), as modified later by Lentin and Williams (1976) and Norris (1978):
(1) 4A(1-4)a / l
(2) 4A(1-4)a / (l(1)P(3)) or I(1) + P(3)
(3) 4A(1-4)a / I(1)a + P(3)a
(4) 4A(1-4)a / (4A(1)-4I(1))
(5) ? 4A(1-4) / 4A(1-4) or ? 4A(1-4)a / 4A(1-4)a.
(1) The above formulae do not include the small preapical paraplates, their loss being considered not directly a part of archeopyle formation.
(2) The number of paraplates in the apical series is probably four but is not yet confirmed.
(3) The intercalary paraplate involved in all the above formulae could be 2a instead of 1a, but we were unable to find any indication in our own material or in earlier illustrations that more than one intercalary paraplate is developed.
(4) The archeopyle type indicated in formula (5) allows the inclusion of the types reported earlier in D. minutum and D. spinosum. However, we consider their interpretation questionable.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Revised descriptions:
Stover and Helby, 1987, p. 281-282
Synopsis:
Cysts camocavate, pericyst lenticular to compressed ellipsoidal, flattened laterally, and with an apical protrusion or horn that may be very
prominent; endocyst outline subcircular to elliptical; periphragm smooth, endophragm smooth or ornamented with features of low to moderate relief; endophragm appressed or much nearer to the periphragm dorsally than ventrally; incomplete paratabulation indicated generally by paracingulum and endo-archeopyle, occasionally by parasutural features on the epi-endocyst; archeopyle apical, type [tA]a.
Description:
Shape: Pericyst lenticular to compressed ellipsoidal, flattened laterally and with an apical protrusion or horn; apical horn with a bluntly rounded to truncate tip which may be open distally. Endocyst outline subcircular to elliptical and without a polar protrusion.
Wall relationships: Cysts camocavate, endocyst eccentrically placed, appressed or much closer to the pericyst dorsally than ventrally; resulting
pericoel usually prominent.
Wall features: Periphragm smooth; endophragm generally thicker than periphragm, smooth or ornamented with granules, verrucae, or short spines. Ornamentation nontabular over all or a substantial part of the endocyst; may be reduced or absent across the apical pole, or on the
epi-endocyst, may occur in faint, longitudinal, parasutural rows and be absent in narrow, longitudinal bands.
Archeopyle: Apical, type [tA]a, principal endoarcheopyle suture generally angular, accessory sutures may be present; operculum normally attached ventrally. Outline of peri-archeopyle commonly uncertain owing to folding and tearing of the periphragm.
Paratabulation: Generally indicated by archeopyle and paracingulum; other expressions, such as parasutural features, confined to epiendocyst; archeopyle sutures indicating 4 apical and 5 or 6 precingular paraplates.
Paracingulum: Usually expressed by parallel, transverse folds of the periphragm; ends slightly to markedly offset ventrally; may be markedly
protrusive dorsally.
Parasulcus: Rarely discernible because of lateral flattening; apparently expressed by weakly developed longitudinal folds on the hypocyst.
Size: Intermediate to large.
Further discussion on Dingodinium in Stover and Helby, 1987, p. 281-282
Affinities:
The combination of features which sets Dingodinium apart is the lateral flattening, the prominent ventral pericoel resulting in the camocavate relationship of the cyst bodies and the attached apical archeopyle. Belodinium Cookson & Eisenack 1960, Boreocysta
Stover & Evitt 1978, and Gardodinium Alberti 1961, possess apical archeopyles, but differ from Dingodinium in being holocavate rather than camocavate and in not being flattened laterally.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Poulsen 1996, p. 81:
Remarks:
In the generic emendation, Stover and Helby (1987) described the archeopyle as apical, type (tA)a. However, neither Dingodinium minutum nor Dingodinium tuberosum have been observed with the operculum attached. At present it is unknown whether it is free or detached.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Dingodinium Cookson and Eisenack, 1958, emend. Mehrotra and Sarjeant, 1984b. According to Stover and Helby (1987, p281),this genus has an apical archeopyle whose operculum is normally attached ventrally. There is no evidence of intercalary plates. It is camocavate.
[Dingodinium, Cookson and Eisenack, 1958, p. 39; Emendations: Mehrota and Sarjeant, 1984b, p. 295, Stover and Helby, 1987d, p.281 as a revised description
Type species: Dingodinium jurassicum, Cookson and Eisenack, 1958 (pl.1, fig.10)]
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: [Cookson and Eisenack, 1958]:
Description:
Theca consisting of a smooth, thin, transparent membrane without plates and a spherical to elongate-oval eccentrically placed capsule either covered with numerous small spines or smooth. A helicoid transverse furrow bounded on either side by a more or less distinct fold is always present on the outer membrane.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Modified description:
Stover and Evitt 1978, p. 229:
Synopsis:
Cysts camocavate, compressed ellipsoidal (flattened laterally), with or without an apical horn; endophragm and periphragm appressed dorsally, separated elsewhere; archeopyle type uncertain, possibly intercalary or combination.
Description:
Shape: Compressed ellipsoidal (flattened laterally), with or without an apical horn; outline of dorsal surface convex to obtusely angular.
Wall relationships: Cysts camocavate; endocyst ellipsoidal, or nearly so, appressed to pericyst dorsally, and separated elsewhere; resulting pericoel usually prominent.
Wall features: No parasutural features. Endophragm thicker than periphragm, smooth or variously ornamented with features of low to moderate relief, which generally do not reach the normally smooth, thinner periphragm.
Paratabulation: Indicated by paracingulum only.
Archeopyle: Type uncertain, possibly intercalary or combination (Type AI). Vague tears in periphragm between paracingulum and base of horn suggest that the archeopyle may be intercalary; however, specimens in which the apical horn is partially detached (adherent ventrally) or completely so suggest that the archeopyle may involve the apical part of the cyst as well as an additional paraplate.
Paracingulum: Usually expressed by parallel transverse folds in the periphragm; may be indicated only faintly.
Parasulcus: Rarely discernible because of lateral flattening; apparently expressed by a few weakly developed longitudinal folds on the hypocyst. Size: Intermediate to large.
Affinities:
Dingodinium and Polygonifera are similar in that each is camocavate; however, the archeopyle type in Polygonifera is apical; and it is uncertain in Dingodinium. Gardodinium differs from Dingodinium in being holocavate, with processes between endophragm and ectophragm, and in having an apical archeopyle.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Emended description:
Mehrota and Sarjeant, 1984:
Diagnosis:
Camocavate dinoflagellate cysts of intermediate to large size. Endoblast ellipsoidal to oval, appressed to periblast on one side (probably dorsal), with a pericoel developed on all other sides. Epipericoel commonly prolonged into an apical horn of variable relative length. Sometimes the periblast and endoblast may show interconnection in the antapical region. Endophragm thicker than periphragm. Endophragm smooth or variously ornamented with features of low to moderate relief; periphragm relatively much thinner, usually smooth, sometimes faintly ornamented with features of very low relief, never projecting out at cyst margin. Parasutural features generally not observed but sometimes indicated on periblast by faint to clearly marked lines, ridges or folds. Cingulum faintly to clearly indicated by transverse folds on periblast; sulcus indicated feebly by longitudinal folds. Paratabulation 2pr, 3-4`, 1-?3a, 0 or 5-6c, 6``, 6```, 1-2p, 1````.
Archeopyle not always distinct, either because it has not developed or because the endoperculum and perioperculum have remained attached and closed again after excystment. Where observable, it is of variable character.
Peripyle consisting always of all apical paraplates; perioperculum simple, usually remaining attached along its ventral surface and closing after excystment. Endopyle either of intercalary (1a or 2a) or of combination apical/intercalary or intercalary/precingular type. Combination archeopyle may involve either an intercalary paraplate (1a or 2a) and all apical paraplates or one intercalary (1a or 2a) and one precingular (3``) paraplate. Endoperculum simple or compound, free or partially or completely attached. Tip of apical horn, comprising the two small paraplates of the preapical series, frequently lost.
Archeopyle formula: The variations of the archeopyle in Dingodinium are presented below in the form of the archeopyle formulae of Evitt (1967), as modified later by Lentin and Williams (1976) and Norris (1978):
(1) 4A(1-4)a / l
(2) 4A(1-4)a / (l(1)P(3)) or I(1) + P(3)
(3) 4A(1-4)a / I(1)a + P(3)a
(4) 4A(1-4)a / (4A(1)-4I(1))
(5) ? 4A(1-4) / 4A(1-4) or ? 4A(1-4)a / 4A(1-4)a.
(1) The above formulae do not include the small preapical paraplates, their loss being considered not directly a part of archeopyle formation.
(2) The number of paraplates in the apical series is probably four but is not yet confirmed.
(3) The intercalary paraplate involved in all the above formulae could be 2a instead of 1a, but we were unable to find any indication in our own material or in earlier illustrations that more than one intercalary paraplate is developed.
(4) The archeopyle type indicated in formula (5) allows the inclusion of the types reported earlier in D. minutum and D. spinosum. However, we consider their interpretation questionable.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Revised descriptions:
Stover and Helby, 1987, p. 281-282
Synopsis:
Cysts camocavate, pericyst lenticular to compressed ellipsoidal, flattened laterally, and with an apical protrusion or horn that may be very
prominent; endocyst outline subcircular to elliptical; periphragm smooth, endophragm smooth or ornamented with features of low to moderate relief; endophragm appressed or much nearer to the periphragm dorsally than ventrally; incomplete paratabulation indicated generally by paracingulum and endo-archeopyle, occasionally by parasutural features on the epi-endocyst; archeopyle apical, type [tA]a.
Description:
Shape: Pericyst lenticular to compressed ellipsoidal, flattened laterally and with an apical protrusion or horn; apical horn with a bluntly rounded to truncate tip which may be open distally. Endocyst outline subcircular to elliptical and without a polar protrusion.
Wall relationships: Cysts camocavate, endocyst eccentrically placed, appressed or much closer to the pericyst dorsally than ventrally; resulting
pericoel usually prominent.
Wall features: Periphragm smooth; endophragm generally thicker than periphragm, smooth or ornamented with granules, verrucae, or short spines. Ornamentation nontabular over all or a substantial part of the endocyst; may be reduced or absent across the apical pole, or on the
epi-endocyst, may occur in faint, longitudinal, parasutural rows and be absent in narrow, longitudinal bands.
Archeopyle: Apical, type [tA]a, principal endoarcheopyle suture generally angular, accessory sutures may be present; operculum normally attached ventrally. Outline of peri-archeopyle commonly uncertain owing to folding and tearing of the periphragm.
Paratabulation: Generally indicated by archeopyle and paracingulum; other expressions, such as parasutural features, confined to epiendocyst; archeopyle sutures indicating 4 apical and 5 or 6 precingular paraplates.
Paracingulum: Usually expressed by parallel, transverse folds of the periphragm; ends slightly to markedly offset ventrally; may be markedly
protrusive dorsally.
Parasulcus: Rarely discernible because of lateral flattening; apparently expressed by weakly developed longitudinal folds on the hypocyst.
Size: Intermediate to large.
Further discussion on Dingodinium in Stover and Helby, 1987, p. 281-282
Affinities:
The combination of features which sets Dingodinium apart is the lateral flattening, the prominent ventral pericoel resulting in the camocavate relationship of the cyst bodies and the attached apical archeopyle. Belodinium Cookson & Eisenack 1960, Boreocysta
Stover & Evitt 1978, and Gardodinium Alberti 1961, possess apical archeopyles, but differ from Dingodinium in being holocavate rather than camocavate and in not being flattened laterally.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Poulsen 1996, p. 81:
Remarks:
In the generic emendation, Stover and Helby (1987) described the archeopyle as apical, type (tA)a. However, neither Dingodinium minutum nor Dingodinium tuberosum have been observed with the operculum attached. At present it is unknown whether it is free or detached.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Dingodinium Cookson and Eisenack, 1958, emend. Mehrotra and Sarjeant, 1984b. According to Stover and Helby (1987, p281),this genus has an apical archeopyle whose operculum is normally attached ventrally. There is no evidence of intercalary plates. It is camocavate.