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Senoniasphaera microreticulata
Senoniasphaera microreticulata Brideaux and McIntyre, 1975
Originally (and now) Senoniasphaera, subsequently Canningia. Below, 1981
transferred this species to Canningia Cookson and Eisenack, 1960; however, Lentin and Williams, 1981 retained it in Senoniasphaera.
Holotype: Brideaux and McIntyre 1975, pl.11, fig.7-9, pl.12, fig.1
Locus typicus: Horton River Formation, District of Mackenzie, Canada
Stratum typicum: Albian
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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.
Senoniasphaera microreticulata Brideaux and McIntyre, 1975. According to Brideaux and McIntyre (1975, p.35), Senoniasphaera microreticulata is two-layered; the periphragm is microreticulate and generally closely appressed to the thicker microreticulate endophragm. One apical prominence, and a rounded or asymmetrically developed antapex, and with cingular bulges. Archeopyle apical; operculum simple and detached or partially attached ventrally. Reflected tabulation of 4', 6", 0c, 5-?6"’, 1"”. Cingulum displaced one to two cingular widths; sulcus offset to the left. Size: periblast length 112-140 µm, width 75-126 µm, endoblast length 105-118 µm, width 75-123 µm.
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Original diagnosis: Brideaux and McIntyre, 1975, p. 35
Cyst two layered; the periphragm microreticulate and generally closely appressed to the thicker microreticulate endophragm. One apical prominence, and a rounded or asymmetrically developed antapex, and with cingular bulges. Archeopyle apical; operculum simple and detached or partially attached ventrally. Reflected tabulation, 4', 6", 0c, 5-?6''', 1''''. Cingulum displaced one to two cingular widths; sulcus offset to the left.
Original description: Brideaux and McIntyre, 1975, p. 35
The periblast outline is subcircular to ovoid with one apical prominence, a slight lateral bulging at the cingulum, and or rounded to asymmetrically developed antapex. Where asymmetrical development of the antapex occurs, the left antapical prominence is more pronounced. The periblast and endoblast are somewhat dorso-ventrally flattened.
The cyst possesses two distinct wall layers which, in well-preserved specimens, are closely appressed except at the apex, the cingular region, and at the antapical prominences. Specimens damaged by maceration, or by natural preservational processes, may show moderate to extreme detachment of the two layers.
The periphragm is a thin microreticulate layer which may be folded or otherwise produced so as to outline reflected tabulation. These folds lie along the course of raised and thickened microreticulate ridges on the underlying endophragm. In specimens from which the periphragm has been stripped, the endophragm can be seen to possess a variable microreticulate to microfossulate sculpture, and occasionally may bear apiculate sculpture. The periphragm,in damaged or degraded specimens, may appear to be connected to the endophragm by a network of fibrous processes. Well-preserved material dispels this impression.
The archeopyle is apical and has a zig-zag margin, indicating the presence of reflected tabulation. The operculum is simple, and may be detached and preserved separately, but is often found close to or partially attached ventrally to the rest of the cyst. The operculum is formed of apical reflected plates 1' to 4' in both the periblast and endoblast (Pl. 11, fig. 11). The reflected tabulation pattern is not clear in all details on each specimen, particularly in the case of the postcingular series. The scheme, as derived from a study of all available material, is: 4', 6", 0c, 5-?6''', 0p, 1''''. The presence of five postcingular reflected plates is confirmed on all well-preserved specimens. A sixth postcingular reflected plate appears to be present on a few specimens, but is not clearly shown.
A cingulum and sulcus are evident on all but the most poorly preserved material. The cingulum follows a slightly sinuous path and is displaced one to two cingular widths on the ventral surface. The sulcus is displaced to the left at its posterior end, is narrow anteriorly, and wide as posteriorly at its junction with the antapical reflected plate.
Dimensions: Periblast: length, 112-140 µm; width, 75-126 µm; endoblast: length, 105-118 µm;width, 75-123 µm.
Affinities:
Brideaux and McIntyre, 1975, p.35: Senoniasphaero sp. of Davey and Verdier,
1971, p. 31, Pl. 6, figs. 7-9, is much smaller. Coming from the Upper Albian of Vallentigny, in northeastern France, it represents the only other Albian occurrence of the genus. The other published species of Senoniosphaera occur in rocks of Late Cretaceous age (Clarke and Verdier, 1967; Williams and Brideaux, 1975).
Originally (and now) Senoniasphaera, subsequently Canningia. Below, 1981
transferred this species to Canningia Cookson and Eisenack, 1960; however, Lentin and Williams, 1981 retained it in Senoniasphaera.
Holotype: Brideaux and McIntyre 1975, pl.11, fig.7-9, pl.12, fig.1
Locus typicus: Horton River Formation, District of Mackenzie, Canada
Stratum typicum: Albian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Senoniasphaera microreticulata Brideaux and McIntyre, 1975. According to Brideaux and McIntyre (1975, p.35), Senoniasphaera microreticulata is two-layered; the periphragm is microreticulate and generally closely appressed to the thicker microreticulate endophragm. One apical prominence, and a rounded or asymmetrically developed antapex, and with cingular bulges. Archeopyle apical; operculum simple and detached or partially attached ventrally. Reflected tabulation of 4', 6", 0c, 5-?6"’, 1"”. Cingulum displaced one to two cingular widths; sulcus offset to the left. Size: periblast length 112-140 µm, width 75-126 µm, endoblast length 105-118 µm, width 75-123 µm.
--------------------------------------------------
Original diagnosis: Brideaux and McIntyre, 1975, p. 35
Cyst two layered; the periphragm microreticulate and generally closely appressed to the thicker microreticulate endophragm. One apical prominence, and a rounded or asymmetrically developed antapex, and with cingular bulges. Archeopyle apical; operculum simple and detached or partially attached ventrally. Reflected tabulation, 4', 6", 0c, 5-?6''', 1''''. Cingulum displaced one to two cingular widths; sulcus offset to the left.
Original description: Brideaux and McIntyre, 1975, p. 35
The periblast outline is subcircular to ovoid with one apical prominence, a slight lateral bulging at the cingulum, and or rounded to asymmetrically developed antapex. Where asymmetrical development of the antapex occurs, the left antapical prominence is more pronounced. The periblast and endoblast are somewhat dorso-ventrally flattened.
The cyst possesses two distinct wall layers which, in well-preserved specimens, are closely appressed except at the apex, the cingular region, and at the antapical prominences. Specimens damaged by maceration, or by natural preservational processes, may show moderate to extreme detachment of the two layers.
The periphragm is a thin microreticulate layer which may be folded or otherwise produced so as to outline reflected tabulation. These folds lie along the course of raised and thickened microreticulate ridges on the underlying endophragm. In specimens from which the periphragm has been stripped, the endophragm can be seen to possess a variable microreticulate to microfossulate sculpture, and occasionally may bear apiculate sculpture. The periphragm,in damaged or degraded specimens, may appear to be connected to the endophragm by a network of fibrous processes. Well-preserved material dispels this impression.
The archeopyle is apical and has a zig-zag margin, indicating the presence of reflected tabulation. The operculum is simple, and may be detached and preserved separately, but is often found close to or partially attached ventrally to the rest of the cyst. The operculum is formed of apical reflected plates 1' to 4' in both the periblast and endoblast (Pl. 11, fig. 11). The reflected tabulation pattern is not clear in all details on each specimen, particularly in the case of the postcingular series. The scheme, as derived from a study of all available material, is: 4', 6", 0c, 5-?6''', 0p, 1''''. The presence of five postcingular reflected plates is confirmed on all well-preserved specimens. A sixth postcingular reflected plate appears to be present on a few specimens, but is not clearly shown.
A cingulum and sulcus are evident on all but the most poorly preserved material. The cingulum follows a slightly sinuous path and is displaced one to two cingular widths on the ventral surface. The sulcus is displaced to the left at its posterior end, is narrow anteriorly, and wide as posteriorly at its junction with the antapical reflected plate.
Dimensions: Periblast: length, 112-140 µm; width, 75-126 µm; endoblast: length, 105-118 µm;width, 75-123 µm.
Affinities:
Brideaux and McIntyre, 1975, p.35: Senoniasphaero sp. of Davey and Verdier,
1971, p. 31, Pl. 6, figs. 7-9, is much smaller. Coming from the Upper Albian of Vallentigny, in northeastern France, it represents the only other Albian occurrence of the genus. The other published species of Senoniosphaera occur in rocks of Late Cretaceous age (Clarke and Verdier, 1967; Williams and Brideaux, 1975).