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Cernicysta helbyi
Cernicysta helbyi, (Morgan, 1980), Stover and Helby, 1987; Emendation: Stover and Helby, 1987d, p.265,267.
Holotype: Morgan, 1980, pl.18, figs.4-6; Fensome et al., 1996, figs.1-3 - p.2149.
Locus typicus: Wanaaring, New South Wales, Australia
Stratum typicum: Middle Aptian-Early Albian
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Original description as Lithodinia helbyi: [Morgan, 1980, p. 26]:
Description:
Double-walled cysts have a subcircular to slightly elliptical ambitus, with moderately high (4-6 µm) parasutural crests;
periphragm thin, often finely granulate; endophragm thicker and rigid, subspherical; wall layers closely appressed in intratabular areas and in the paracingulum, separated beneath inflated parasutural crests; inflation of parasutural crests greater around precingular and postcingular plates than along the paracingulum; crests often distorted or collapsed due to thin nature of periphragm,
paratabulation gonyaulacean;
paracingulum relatively broad (8-10 µm) relative to total cyst length (55-60 µm);
archeopyle apical, operculum free.
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Revised description:
Stover and Helby, 1987, p. 265-266:
Description:
Cyst proximate, outline circular to elliptical in dorsal ventral view, elliptical in apical antapical view with the transverse axis longer than the dorsal ventral axis.
Cyst walls 2- layered with the inner one the thicker. Autophragm and ectophragm may be narrowly separated or appressed over most of the cyst, and more widely separated where parasutural folds or septa are developed. Ectocoel with numerous, slender, curved, generally intersecting, occasionally isolated, fibrous projections so that the ectophragm appears punctogranulate in plan view.
Archeopyle apical, type [tA], with a relatively deep parasulcal notch. Principal archeopyle suture only slightly angular on the dorsal surface and inclined toward the parasulcus on the ventral surface; accessory archeopyle sutures, when developed, short. Operculum free.
Parasutural folds and septa 2.5-6 µm in height; paratabulation formula: 3-4'?, 6'', Xc, 5''', 1p, 1'''' . Apical paraplates poorly delineated, exact number and shapes undetermined but there are at least three apical paraplates. In the precingular series, paraplates 2'' to 5'' quadrangular; anterior ventral margins of 1'' and 6" slope towards parasulcal notch, and 1'' significantly shorter longitudinally than 6''. Postcingular paraplates essentially quadrangular, differing considerably in size. Paraplate 1''' smallest; 3''' and 5''' substantially larger, higher than wide, and 3''' is middorsal; two adjacent paraplates (2''' and 4''' ) equidimensional, or nearly so, and much wider than 3'''; anterior ventral margin of 5''' slopes toward the parasulcus on some specimens. Posterior intercalary paraplate quadrate, higher than wide, and intermediate in size between 1''' and 3''' . Antapical paraplate 6-sided (standard gonyaulacacean type) with the 3 short sides facing ventrally. Noteworthy relationships between parasutural features of the precingular and postcingular series are that the parasutural features between 1" /2'' and 1'''/2''' on the left side are more or less in line, the same as 5" /6" and 4'''/5''' on the right side. In contrast, intervening, parasutural features in 3 both series on the dorsal surface offset (Fig.6B). Middorsal fold or septum between 3'' and 4'' especially interesting.
Paracingulum indicated by transverse, parallel folds or septa, generally undivided. with end. Offset by approximately half the width of the paracingulum.
Parasulcus indicated anteriorly by the parasulcal notch, and elsewhere by the margins of the bordering paraplates. On some specimens, a posterior sulcal paraplate differentiated, and indefinite markings discernible, usually in the area between the ends of the paracingulum and between paraplates 1''' and 5'''.
Variability: Except for differences in shape, size. and the height of the parasutural features, specimens of Cernicysta helbyi show little variability.
Dimensions:
Specimens 49-60 µm in length, 36-53 µm in width; 15 specimens measured. Measurements include those given by Morgan (1980, p.26).
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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cernicysta helbyi (Morgan, 1980) Stover and Helby, 1987d, emend. Stover and Helby, 1987d. This is proximate with circular to elliptical outline in dorsal-ventral view, and elliptical outline in apical- antapical view. Autophragm and ectophragm narrowly separated or appressed over most of the cyst and most widely separated where parasutural folds or septa are developed. Ectophragm with fibrous projections. Archeopyle apical with free operculum. Discernible tabulation 6", 5"’, 1p, 1"”. The first posterior intercalary is large, almost equal to 5"’ in size.
Size: 49-60 microns in length.
Holotype: Morgan, 1980, pl.18, figs.4-6; Fensome et al., 1996, figs.1-3 - p.2149.
Locus typicus: Wanaaring, New South Wales, Australia
Stratum typicum: Middle Aptian-Early Albian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Lithodinia helbyi: [Morgan, 1980, p. 26]:
Description:
Double-walled cysts have a subcircular to slightly elliptical ambitus, with moderately high (4-6 µm) parasutural crests;
periphragm thin, often finely granulate; endophragm thicker and rigid, subspherical; wall layers closely appressed in intratabular areas and in the paracingulum, separated beneath inflated parasutural crests; inflation of parasutural crests greater around precingular and postcingular plates than along the paracingulum; crests often distorted or collapsed due to thin nature of periphragm,
paratabulation gonyaulacean;
paracingulum relatively broad (8-10 µm) relative to total cyst length (55-60 µm);
archeopyle apical, operculum free.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Revised description:
Stover and Helby, 1987, p. 265-266:
Description:
Cyst proximate, outline circular to elliptical in dorsal ventral view, elliptical in apical antapical view with the transverse axis longer than the dorsal ventral axis.
Cyst walls 2- layered with the inner one the thicker. Autophragm and ectophragm may be narrowly separated or appressed over most of the cyst, and more widely separated where parasutural folds or septa are developed. Ectocoel with numerous, slender, curved, generally intersecting, occasionally isolated, fibrous projections so that the ectophragm appears punctogranulate in plan view.
Archeopyle apical, type [tA], with a relatively deep parasulcal notch. Principal archeopyle suture only slightly angular on the dorsal surface and inclined toward the parasulcus on the ventral surface; accessory archeopyle sutures, when developed, short. Operculum free.
Parasutural folds and septa 2.5-6 µm in height; paratabulation formula: 3-4'?, 6'', Xc, 5''', 1p, 1'''' . Apical paraplates poorly delineated, exact number and shapes undetermined but there are at least three apical paraplates. In the precingular series, paraplates 2'' to 5'' quadrangular; anterior ventral margins of 1'' and 6" slope towards parasulcal notch, and 1'' significantly shorter longitudinally than 6''. Postcingular paraplates essentially quadrangular, differing considerably in size. Paraplate 1''' smallest; 3''' and 5''' substantially larger, higher than wide, and 3''' is middorsal; two adjacent paraplates (2''' and 4''' ) equidimensional, or nearly so, and much wider than 3'''; anterior ventral margin of 5''' slopes toward the parasulcus on some specimens. Posterior intercalary paraplate quadrate, higher than wide, and intermediate in size between 1''' and 3''' . Antapical paraplate 6-sided (standard gonyaulacacean type) with the 3 short sides facing ventrally. Noteworthy relationships between parasutural features of the precingular and postcingular series are that the parasutural features between 1" /2'' and 1'''/2''' on the left side are more or less in line, the same as 5" /6" and 4'''/5''' on the right side. In contrast, intervening, parasutural features in 3 both series on the dorsal surface offset (Fig.6B). Middorsal fold or septum between 3'' and 4'' especially interesting.
Paracingulum indicated by transverse, parallel folds or septa, generally undivided. with end. Offset by approximately half the width of the paracingulum.
Parasulcus indicated anteriorly by the parasulcal notch, and elsewhere by the margins of the bordering paraplates. On some specimens, a posterior sulcal paraplate differentiated, and indefinite markings discernible, usually in the area between the ends of the paracingulum and between paraplates 1''' and 5'''.
Variability: Except for differences in shape, size. and the height of the parasutural features, specimens of Cernicysta helbyi show little variability.
Dimensions:
Specimens 49-60 µm in length, 36-53 µm in width; 15 specimens measured. Measurements include those given by Morgan (1980, p.26).
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Cernicysta helbyi (Morgan, 1980) Stover and Helby, 1987d, emend. Stover and Helby, 1987d. This is proximate with circular to elliptical outline in dorsal-ventral view, and elliptical outline in apical- antapical view. Autophragm and ectophragm narrowly separated or appressed over most of the cyst and most widely separated where parasutural folds or septa are developed. Ectophragm with fibrous projections. Archeopyle apical with free operculum. Discernible tabulation 6", 5"’, 1p, 1"”. The first posterior intercalary is large, almost equal to 5"’ in size.
Size: 49-60 microns in length.