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Perisseiasphaeridium pannosum
Perisseisphaeridium pannosum Davey and Williams, 1966
Holotype: Davey and Williams, 1966, pl.11, fig.8; Bujak et al., 1980, pl.2, figs.7-8
Locus typicus: London Clay, Isle of Wight, England
Stratum typicum: Early Eocene (possibly reworked Jurassic, according to Fensome, 1979)
Recorded occurrences: Denmark: Endoscrinium luridum Zone, Perisseiasphaeridium pannosum Subzone - Dingodinium spinosum Zone; Poland: Mid-Divisum - Autissiodorensis Zones.
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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.
Perisseiasphaeridium pannosum Davey and Williams, 1966b. This is chorate, subspherical to ovoidal, bearing two types of processes. The first are broad, open infundibular processes, which are often fenestrate distally. The second type are smaller, slender, closed, with simple or bifurcate extremities. Apical archeopyle present. The large processes have an irregular digitate margin, each branch being further split up into evexate, bulbous or bifid secae. The secae and/or digitae may be interconnected thus giving rise to a fenestrate structure. The slender processes are about 1 µm wide. Size: diameter of central body 42-57 µm, length of infundibular processes 24-40 µm, width of same up to 9 µm, proximally, 34 µm distally, length of slender processes up to 27 µm.
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Original diagnosis: Davey and Williams, 1966, p. 78
Chorate, sub-spherical to ovoidal cyst bearing two types of processes. One with broad open infundibular processes, often fenestrate distally; the other with smaller slender processes, closed, with simple or bifurcate extremities.
Apical archaeopyle present.
Dimensions:
Holotype: diameter of central body 42.5 by 43 µm length of infundibular processes 24-29 µm; length of slender processes up to 19 µm. Range: diameter of central body 42-57 µm; length of infundibular processes 24-40 µm; width of infundibular processes up to 9 µm proximally, 34 µm distally; length of slender processes up to 27 µm.
Original description: Davey and Williams, 1966, p. 79
This species has very distinctive infundibular processes with an irregular digitate margin, each branch being further split up into evexate, bulbous or bifid secae. The secae and/or the digitae may be inter-connected, thus giving rise to a fenestrate structure. The tabulation reflected by the infundibular processes is 4', 6'', 5''', Ip, 1''''. In addition there are some very slender processes, less than 1 µm wide, restricted to the cingulum and sulcal zones. These processes are always closed, and are either acuminate or irregularly bifurcate. The exact number is variable and difficult to determine.
Affinities:
Davey and Williams, 1966, p. 79: This species differs from Oligosphaeridium pulcherimum (Deflandre & Cookson) from the Australian Lower Cretaceous, in the nature of the fenestrate, infundibular processes. The slender cingular and sulcal processes are a characteristic feature.
Poulsen, 1996, p. 65 Perisseiasphaeridium pannosum Davey & Williams 1966 Pl. 32, Figs. 4-6
Remarks:
This form has large tubiform, fenestrate processes with distal digitations and highly irregular margins. The degree of fenestration and digitation varies. In some cysts the margins are deeply divided with minor fenestrations. The processes have a simple appearance. In other specimens the processes are highly fenestrate distally and simultaneously less deeply digitate; these processes have a complex appearance. At present both types are attributed to P. pannosum, but may prove to be two distinct species.
P. pannosum was first described as a Tertiary species, but is now widely recorded from the Jurassic (the Tertiary records are most likely reworked specimens, Fensome, 1979; Nohr-Hansen, 1986; Riding and Thomas, 1988; 1992).
Holotype: Davey and Williams, 1966, pl.11, fig.8; Bujak et al., 1980, pl.2, figs.7-8
Locus typicus: London Clay, Isle of Wight, England
Stratum typicum: Early Eocene (possibly reworked Jurassic, according to Fensome, 1979)
Recorded occurrences: Denmark: Endoscrinium luridum Zone, Perisseiasphaeridium pannosum Subzone - Dingodinium spinosum Zone; Poland: Mid-Divisum - Autissiodorensis Zones.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Perisseiasphaeridium pannosum Davey and Williams, 1966b. This is chorate, subspherical to ovoidal, bearing two types of processes. The first are broad, open infundibular processes, which are often fenestrate distally. The second type are smaller, slender, closed, with simple or bifurcate extremities. Apical archeopyle present. The large processes have an irregular digitate margin, each branch being further split up into evexate, bulbous or bifid secae. The secae and/or digitae may be interconnected thus giving rise to a fenestrate structure. The slender processes are about 1 µm wide. Size: diameter of central body 42-57 µm, length of infundibular processes 24-40 µm, width of same up to 9 µm, proximally, 34 µm distally, length of slender processes up to 27 µm.
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Original diagnosis: Davey and Williams, 1966, p. 78
Chorate, sub-spherical to ovoidal cyst bearing two types of processes. One with broad open infundibular processes, often fenestrate distally; the other with smaller slender processes, closed, with simple or bifurcate extremities.
Apical archaeopyle present.
Dimensions:
Holotype: diameter of central body 42.5 by 43 µm length of infundibular processes 24-29 µm; length of slender processes up to 19 µm. Range: diameter of central body 42-57 µm; length of infundibular processes 24-40 µm; width of infundibular processes up to 9 µm proximally, 34 µm distally; length of slender processes up to 27 µm.
Original description: Davey and Williams, 1966, p. 79
This species has very distinctive infundibular processes with an irregular digitate margin, each branch being further split up into evexate, bulbous or bifid secae. The secae and/or the digitae may be inter-connected, thus giving rise to a fenestrate structure. The tabulation reflected by the infundibular processes is 4', 6'', 5''', Ip, 1''''. In addition there are some very slender processes, less than 1 µm wide, restricted to the cingulum and sulcal zones. These processes are always closed, and are either acuminate or irregularly bifurcate. The exact number is variable and difficult to determine.
Affinities:
Davey and Williams, 1966, p. 79: This species differs from Oligosphaeridium pulcherimum (Deflandre & Cookson) from the Australian Lower Cretaceous, in the nature of the fenestrate, infundibular processes. The slender cingular and sulcal processes are a characteristic feature.
Poulsen, 1996, p. 65 Perisseiasphaeridium pannosum Davey & Williams 1966 Pl. 32, Figs. 4-6
Remarks:
This form has large tubiform, fenestrate processes with distal digitations and highly irregular margins. The degree of fenestration and digitation varies. In some cysts the margins are deeply divided with minor fenestrations. The processes have a simple appearance. In other specimens the processes are highly fenestrate distally and simultaneously less deeply digitate; these processes have a complex appearance. At present both types are attributed to P. pannosum, but may prove to be two distinct species.
P. pannosum was first described as a Tertiary species, but is now widely recorded from the Jurassic (the Tertiary records are most likely reworked specimens, Fensome, 1979; Nohr-Hansen, 1986; Riding and Thomas, 1988; 1992).