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Stiphrosphaeridium arbustum
Stiphrosphaeridium arbustum Davey, 1982
Holotype: Davey 1982, pl. 3, figs. 1-2
Locus typicus: Haldager No.1, Denmark
Stratum typicum: Ryazanian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Stiphrosphaeridium arbustum Davey, 1982b. Diagnosis from Davey (1982b, p.17-18), the body is subspherical with two wall layers closely appressed, except in areas of processes. Surface almost smooth. The plate-centred processes vary considerably in size, particularly in width, with the smallest being 1"1"’, 1p and the parasulcal process(es). The larger processes are poorly to complexly fenestrate; distally each termination with an incompletely developed circular trabeculum which is slightly spinous distally. Where trabeculae are not developed the processes are distally irregularly aculeate and secate. The more proximal parts of the incompletely fenestrate processes are solid, hollow with a restricted lumen or very rarely hollow. Internal vacuoles are often present. The process formula is 4', 6", 6"’, 1"”, 1ps, plus 0-1s. Archeopyle apical. Size; body length with archeopyle developed 44-62 µm, width 40-69 µm, process length 18-38 µm.
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Original diagnosis: Davey, 1982, p. 17
Shape: The body is subspherical in shape.
Wall: The two layers of the cyst wall are closely appressed except where the periphragm forms the processes. The surface is almost smooth.
Processes: The plate-centred processes vary considerably in size, particularly in width, with the smallest being 1'''', 1p and the parasulcal process(es). The larger processes are poorly to complexly fenestrate: distally each terminates with an incompletely developed circular trabeculum which is slightly spinous distally. Where trabeculae are not developed the processes are distally irregularly aculeate and secate. The more proximal parts of the incompletely fenestrate processes are solid. hollow with a restricted lumen or very rarely hollow. Internal vacuoles are often present. The process formula is 4', 6", 6''', 1'''', lps, plus 0-1s.
Archaeopyle: An apical archaeopyle (Type A) is typically developed.
Original description: Davey, 1982, p. 17
The cyst wall is relatively thin (less than 1 µm) and because of this is easily distorted and broken. The processes vary from approximately 1 to 7 µm in stem width with the pre-, postcingular and antapical processes being the widest. In some of these latter processes the fenestration continues to the body surface so giving rise to what could be termed narrow-based annulate complexes. Usually, however, fenestration commences medially to distally and the more proximal parts of the processes are solid. Occasionally the internal vacuoles in the processes appear to have joined so giving a hollow process. Rarely this is well developed and the lumen of the stem appears to be confluent with the distal fenestrate funnel of the process so giving a tubiform process. Typically the stem walls of these processes are fenestrate.
Holotype: Davey 1982, pl. 3, figs. 1-2
Locus typicus: Haldager No.1, Denmark
Stratum typicum: Ryazanian
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999
Stiphrosphaeridium arbustum Davey, 1982b. Diagnosis from Davey (1982b, p.17-18), the body is subspherical with two wall layers closely appressed, except in areas of processes. Surface almost smooth. The plate-centred processes vary considerably in size, particularly in width, with the smallest being 1"1"’, 1p and the parasulcal process(es). The larger processes are poorly to complexly fenestrate; distally each termination with an incompletely developed circular trabeculum which is slightly spinous distally. Where trabeculae are not developed the processes are distally irregularly aculeate and secate. The more proximal parts of the incompletely fenestrate processes are solid, hollow with a restricted lumen or very rarely hollow. Internal vacuoles are often present. The process formula is 4', 6", 6"’, 1"”, 1ps, plus 0-1s. Archeopyle apical. Size; body length with archeopyle developed 44-62 µm, width 40-69 µm, process length 18-38 µm.
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Original diagnosis: Davey, 1982, p. 17
Shape: The body is subspherical in shape.
Wall: The two layers of the cyst wall are closely appressed except where the periphragm forms the processes. The surface is almost smooth.
Processes: The plate-centred processes vary considerably in size, particularly in width, with the smallest being 1'''', 1p and the parasulcal process(es). The larger processes are poorly to complexly fenestrate: distally each terminates with an incompletely developed circular trabeculum which is slightly spinous distally. Where trabeculae are not developed the processes are distally irregularly aculeate and secate. The more proximal parts of the incompletely fenestrate processes are solid. hollow with a restricted lumen or very rarely hollow. Internal vacuoles are often present. The process formula is 4', 6", 6''', 1'''', lps, plus 0-1s.
Archaeopyle: An apical archaeopyle (Type A) is typically developed.
Original description: Davey, 1982, p. 17
The cyst wall is relatively thin (less than 1 µm) and because of this is easily distorted and broken. The processes vary from approximately 1 to 7 µm in stem width with the pre-, postcingular and antapical processes being the widest. In some of these latter processes the fenestration continues to the body surface so giving rise to what could be termed narrow-based annulate complexes. Usually, however, fenestration commences medially to distally and the more proximal parts of the processes are solid. Occasionally the internal vacuoles in the processes appear to have joined so giving a hollow process. Rarely this is well developed and the lumen of the stem appears to be confluent with the distal fenestrate funnel of the process so giving a tubiform process. Typically the stem walls of these processes are fenestrate.