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Dingodinium cerviculum
Dingodinium cerviculum Cookson and Eisenack, 1958, p.40, pl.1, figs.12-14. Emendations: Mehrotra and Sarjeant, 1984b, p.296-300; Khowaja-Ateequzzaman et al., 1990, p.274.
Taxonomic junior synonym: Dingodinium? albertii, according to Haskell (1970, p.60) and Khowaja-Ateequzzaman et al. (1990, p.274).
Holotype: Cookson and Eisenack, 1958, pl.1, fig.14.
Age: Late Neocomian-Aptian.
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Dingodinium cerviculum Cookson and Eisenack, 1958, emend. Khowaja-Atteequzzaman et al., 1990. According to Khowaja-Ateequzzaman et al (1990), this is a camocavate cyst, laterally compressed, endocyst eccentrically placed shifted towards dorsal side, sometimes appressed, pericoel prominent ventrally; pericyst ellipsoidal with a well-developed apical horn, periphragm thin, smooth, an opening (claustrum) generally developed on ventral side at posterior sulcal region; endocyst ellipsoidal, endophragm thick, ornamented with tubercles, verrucae and spines, usually arranged in longitudinal rows: archeopyle differently developed on epicyst and endocyst, periarcheopyle intercalary involving more than one anterior intercalary paraplates, probably 3, perioperculum free, endoarcheopyle combination type involving four apical and three anterior intercalary paraplates, endoperculum in two parts, adnate apical and free intercalary, accessory archeopyle sutures develop along precingular paraplates, paracingulum distinct on periphragm, helicoid, markedly offset ventrally, paratabulation incompletely discernible. Size: overall 81-109 x 33-66 µm, capsule 47-65 x 28-52 µm.
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Original description: Cookson and Eisenack, 1958, p. 40
Description: Theca longer than broad, its outer membrane narrowing towards a relatively long terminal neck the end of which, in well preserved specimens, appears to be closed. The girdle is clearly defined and helicoid. The capsule is elongated longitudinally and usually flattened on the side in contact with the outer membrane; it is covered with small spine-like outgrowths which may be arranged in regular longitudinal rows or scattered irregularly over the surface.
Dimensions: Type 109x66 Ám overall; capsule 65x52 Ám. Range 81-109x33-66 Ám; capsule 47-65 x28-52 Ám.
Comments: The real affinity of the Dingodinium cannot be fixed with certainty. The presence of a girdle indicates relationship with the Dinoflagellata, the occurrence of a capsule within a thin enclosing membrane suggesting a position near the family Deflandreidae.
Emended diagnosis: Mehrota and Sarjeant, 1984, p. 297
Elongate camocavate cysts, typically with a moderate to well-developed apical horn. Periphragm thin, usually smooth, sometimes faintly ornamented. Endophragm relatively thick, ornamented densely with tubercles or echinae; these having a broad base and pointed ends and may be arranged in regular fashion (as rows) or haphazardly. Cingulum typically distinct, marked by periphragm folds. Sulcus clearly seen only sometimes; parasutural features rarely observed. Paratabulation, when determinable, 2pr, 3-4', ?1a, 6'', 6''', 1-2p, 1''''; cingulum clearly present but undivided.
Archeopyle distinct or indistinct. When distinct, it consists of a peripyle and an endopyle. Peripyle comprises all the apical paraplates; usually it remains attached, closing after excystment. Endopyle intercalary (1a or 2a) or of combination (intercalary/precingular) type. Endoperculum simple or compound, free or attached in part or wholly. In addition, the tip of the apical horn, comprising the two small preapical paraplates, frequently is lost.
Archeopyle variations observed are of the types 4A(1-4)a / I(1) or 4A(1-4)a / (I(1)P(3)) or 4A(1-4)a / I(1a) + P(3a) -as per the classification of Evitt (1967), modified by Lentin and Williams (1976) and Norris (1978). Apical paraplates involved may be three instead of four.
Dimensions: Intermediate to large. Overall length of complete specimens 50-138 Ám.
Further disccussion on D. cerviculum: Mehrota and Sarjeant, 1984, p.298, 300
Emended diagnosis: Khowaja-Ateequzzaman et al., 1990, p.274
Cyst camocavate, laterally compressed, endocyst eccentrically placed shifted towards dorsal side, sometimes appressed, pericoel prominent ventrally; pericyst ellipsoidal with a well-developed apical horn, periphragm thin, smooth, an opening (claustrum) generally developed on ventral side at posterior sulcal region; endocyst ellipsoidal, endophragm thick, ornamented with tubercles, verrucae and spines, usually arranged in longitudinal rows; archaeopyle differently developed on epicyst and endocyst, periarchaeopyle intercalary involving more than one anterior intercalary paraplates, probably 3, perioperculum free, endoarchaeopyle, combination type involving four apical and three anterior intercalary paraplates, endoperculum in two parts, adnate apical and free intercalary, accessory archaeopyle sutures develop along precingular paraplates, paracingulum distinct on periphragm, helicoid, markedly offset ventrally; paratabulation, incompletely discernible.
Description: Khowaja-Ateequzzaman et al., 1990, p.275
1.Shape--Cyst laterally compressed, ellipsoidal, epipericyst prolonged into an apical horn with a bluntly rounded tip, endocyst ellipsoidal.
Wall relationship-Cyst camocavate, endocyst eccentrically placed, shifted more towards dorsal side, some times almost appressed dorsally in precingular and post-cingular areas, pericoel well-developed ventrally.
Wall features--Periphragm extremely thin, smooth without any parasutural features, an opening (claustrum) invariably present on ventral surface somewhere in the posterior sulcal region, tip of the apical horn generally open, endophragm thick, ornamented with verrucae, tubercles and short spines arranged in longitudinal rows, ornamentation partly tabular, well-defined in endocyst.
Paracingulum--Distinct on periphragm, expressed bv parallel transverse folds running high over endophragm, markedly offset ventrally. Paratabulation--Incompletely indicated by periarchaeopyle and undivided periparacingulum on pericyst; differently developed on endocyst; complete on epiendocyst indicated by endoarchaeopyle and tabular ornamentation, poorly and incompletely expressed on hypoendocyst; endocyst formula 4', 3a, 7", Xc, X''', X''''.
Archaeopyle--Differently developed on periphragm and endophragm; periarchaeopyle intercalary, involving more than one, probably three, anterior intercalary paraplates, operculum free; endoarchaeopyle combination type involving all four apical and three anterior intercalary paraplates; endoperculum compound, represented in two parts; an apical free part which is polyplacoid, simple and adnate while the other part comprising intercalary paraplates is polyplacoid, free and probably compound. Formula ?2-3I/(4A)a3I.
Affinities:
Stover an Helby, 1987, p. 282: Haskell (1969, p.60) and Habib (1976, p.382) considered D. albertii to be a junior subjective synonym of D. cerviculum. However, Duxbury (1977, p.29) and Davey (1978, p.894) refuted the proposed synonymy on the grounds of a size difference. On the basis of published information, and on our observations on D. cerviculum from the Houtman-l well, we favour Duxbury's and Davey's position. In addition to the size difference endocysts of D. albertii tend to be subcircular in outline rather than elliptical and the epipericoels are much smaller than those of D. cerviculum.
Taxonomic junior synonym: Dingodinium? albertii, according to Haskell (1970, p.60) and Khowaja-Ateequzzaman et al. (1990, p.274).
Holotype: Cookson and Eisenack, 1958, pl.1, fig.14.
Age: Late Neocomian-Aptian.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Dingodinium cerviculum Cookson and Eisenack, 1958, emend. Khowaja-Atteequzzaman et al., 1990. According to Khowaja-Ateequzzaman et al (1990), this is a camocavate cyst, laterally compressed, endocyst eccentrically placed shifted towards dorsal side, sometimes appressed, pericoel prominent ventrally; pericyst ellipsoidal with a well-developed apical horn, periphragm thin, smooth, an opening (claustrum) generally developed on ventral side at posterior sulcal region; endocyst ellipsoidal, endophragm thick, ornamented with tubercles, verrucae and spines, usually arranged in longitudinal rows: archeopyle differently developed on epicyst and endocyst, periarcheopyle intercalary involving more than one anterior intercalary paraplates, probably 3, perioperculum free, endoarcheopyle combination type involving four apical and three anterior intercalary paraplates, endoperculum in two parts, adnate apical and free intercalary, accessory archeopyle sutures develop along precingular paraplates, paracingulum distinct on periphragm, helicoid, markedly offset ventrally, paratabulation incompletely discernible. Size: overall 81-109 x 33-66 µm, capsule 47-65 x 28-52 µm.
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Original description: Cookson and Eisenack, 1958, p. 40
Description: Theca longer than broad, its outer membrane narrowing towards a relatively long terminal neck the end of which, in well preserved specimens, appears to be closed. The girdle is clearly defined and helicoid. The capsule is elongated longitudinally and usually flattened on the side in contact with the outer membrane; it is covered with small spine-like outgrowths which may be arranged in regular longitudinal rows or scattered irregularly over the surface.
Dimensions: Type 109x66 Ám overall; capsule 65x52 Ám. Range 81-109x33-66 Ám; capsule 47-65 x28-52 Ám.
Comments: The real affinity of the Dingodinium cannot be fixed with certainty. The presence of a girdle indicates relationship with the Dinoflagellata, the occurrence of a capsule within a thin enclosing membrane suggesting a position near the family Deflandreidae.
Emended diagnosis: Mehrota and Sarjeant, 1984, p. 297
Elongate camocavate cysts, typically with a moderate to well-developed apical horn. Periphragm thin, usually smooth, sometimes faintly ornamented. Endophragm relatively thick, ornamented densely with tubercles or echinae; these having a broad base and pointed ends and may be arranged in regular fashion (as rows) or haphazardly. Cingulum typically distinct, marked by periphragm folds. Sulcus clearly seen only sometimes; parasutural features rarely observed. Paratabulation, when determinable, 2pr, 3-4', ?1a, 6'', 6''', 1-2p, 1''''; cingulum clearly present but undivided.
Archeopyle distinct or indistinct. When distinct, it consists of a peripyle and an endopyle. Peripyle comprises all the apical paraplates; usually it remains attached, closing after excystment. Endopyle intercalary (1a or 2a) or of combination (intercalary/precingular) type. Endoperculum simple or compound, free or attached in part or wholly. In addition, the tip of the apical horn, comprising the two small preapical paraplates, frequently is lost.
Archeopyle variations observed are of the types 4A(1-4)a / I(1) or 4A(1-4)a / (I(1)P(3)) or 4A(1-4)a / I(1a) + P(3a) -as per the classification of Evitt (1967), modified by Lentin and Williams (1976) and Norris (1978). Apical paraplates involved may be three instead of four.
Dimensions: Intermediate to large. Overall length of complete specimens 50-138 Ám.
Further disccussion on D. cerviculum: Mehrota and Sarjeant, 1984, p.298, 300
Emended diagnosis: Khowaja-Ateequzzaman et al., 1990, p.274
Cyst camocavate, laterally compressed, endocyst eccentrically placed shifted towards dorsal side, sometimes appressed, pericoel prominent ventrally; pericyst ellipsoidal with a well-developed apical horn, periphragm thin, smooth, an opening (claustrum) generally developed on ventral side at posterior sulcal region; endocyst ellipsoidal, endophragm thick, ornamented with tubercles, verrucae and spines, usually arranged in longitudinal rows; archaeopyle differently developed on epicyst and endocyst, periarchaeopyle intercalary involving more than one anterior intercalary paraplates, probably 3, perioperculum free, endoarchaeopyle, combination type involving four apical and three anterior intercalary paraplates, endoperculum in two parts, adnate apical and free intercalary, accessory archaeopyle sutures develop along precingular paraplates, paracingulum distinct on periphragm, helicoid, markedly offset ventrally; paratabulation, incompletely discernible.
Description: Khowaja-Ateequzzaman et al., 1990, p.275
1.Shape--Cyst laterally compressed, ellipsoidal, epipericyst prolonged into an apical horn with a bluntly rounded tip, endocyst ellipsoidal.
Wall relationship-Cyst camocavate, endocyst eccentrically placed, shifted more towards dorsal side, some times almost appressed dorsally in precingular and post-cingular areas, pericoel well-developed ventrally.
Wall features--Periphragm extremely thin, smooth without any parasutural features, an opening (claustrum) invariably present on ventral surface somewhere in the posterior sulcal region, tip of the apical horn generally open, endophragm thick, ornamented with verrucae, tubercles and short spines arranged in longitudinal rows, ornamentation partly tabular, well-defined in endocyst.
Paracingulum--Distinct on periphragm, expressed bv parallel transverse folds running high over endophragm, markedly offset ventrally. Paratabulation--Incompletely indicated by periarchaeopyle and undivided periparacingulum on pericyst; differently developed on endocyst; complete on epiendocyst indicated by endoarchaeopyle and tabular ornamentation, poorly and incompletely expressed on hypoendocyst; endocyst formula 4', 3a, 7", Xc, X''', X''''.
Archaeopyle--Differently developed on periphragm and endophragm; periarchaeopyle intercalary, involving more than one, probably three, anterior intercalary paraplates, operculum free; endoarchaeopyle combination type involving all four apical and three anterior intercalary paraplates; endoperculum compound, represented in two parts; an apical free part which is polyplacoid, simple and adnate while the other part comprising intercalary paraplates is polyplacoid, free and probably compound. Formula ?2-3I/(4A)a3I.
Affinities:
Stover an Helby, 1987, p. 282: Haskell (1969, p.60) and Habib (1976, p.382) considered D. albertii to be a junior subjective synonym of D. cerviculum. However, Duxbury (1977, p.29) and Davey (1978, p.894) refuted the proposed synonymy on the grounds of a size difference. On the basis of published information, and on our observations on D. cerviculum from the Houtman-l well, we favour Duxbury's and Davey's position. In addition to the size difference endocysts of D. albertii tend to be subcircular in outline rather than elliptical and the epipericoels are much smaller than those of D. cerviculum.