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Kleithriasphaeridium readei
Kleithriasphaeridium readei (Davey and Williams, 1966) emend. Davey and Verdier, 1976
Originally Hystrichosphaeridium, subsequently (and now) Kleithriasphaeridium.
Holotype: Davey and Williams, 1966, pl.6, fig.3
Locus typicus: Fetcham Mill, England
Stratum typicum: Cenomanian
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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.
Kleithriasphaeridium readei (Davey and Williams, 1966b) Davey and Verdier, 1976, emend. Davey and Verdier, 1976. According to Davey and Verdier (1976, p.314), this species has a spherical to subspherical smooth-walled cyst and possesses one tubular process per plate. Processes slightly fibrous, tubiform and are open distally, terminating with a spiny to secate margin. They do not vary much in width except to become narrow when they are sulcal. The processes have three or four thickenings or ribs extending along their length. Each rib continues onto and over the central body surface to a rib on a neighbouring process. Archeopyle precingular. Size: central body diameter 31-54 µm, process length 20-35 µm.
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Original diagnosis: Davey and Williams, 1966, p. 64: Hystrichosphaeridium readei
Spherical to subspherical central body composed of smooth endophragm and periphragm. Processes, composed of the latter, slightly fibrous, cylindrical and open. Larger processes with two thickenings of periphragm extending along their length over surface of central body and joining up with similar thickenings from neighbouring processes. Processes varying in width and expanding distally, terminating in fairly complicated aculeate or secate margin. Apical archaeopyle usually present.
Dimensions: holotype: diameter of central body 41 by 45 Ám, length of processes 23-29 Ám, number of processes 24. Range: diameter of central body 31-54 Ám, length of processes 20-35 Ám.
Original description: Davey and Williams, 1966, p. 64: Hystrichosphaeridium readei
The most characteristic feature of this species is the presence of thickenings or ribs in the periphragm. These ribs are close together near the distal end of the process and gradually diverge proximally, before separating completely on the surface of the central body, each rib passing to a different neighbouring process. Thus triangular and polygonal networks are seen on the surface of the central body.
The sulcal processes are usually noticeably finer than the others and are very occasionally joined by septa, as seen in the holotype. The septa are probably modified ribs. An apical archaeopyle is usually present. The number of processes in the specimens observed varied between 23 and 27. The reflected tabulation is difficult to determine but it is probably comparable to H. tllbiferum i.e. 4', 6", 6c, 5''', 1p, 1'''' and xs.
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Emended diagnosis: Davey and Verdier 1976, p. 314: Kleithriasphaeridium readei
The cyst is spherical to subspherical, smooth-walled and possesses one tubular process per reflected plate area. The processes are slightly fibrous, tubiform and are open distally terminating with a spiny to secate margin; they do not usually vary very much in width except to become narrow when they are present in the sulcal region. The processes have three or four thickenings or ribs extending along their length. Each rib continues onto and over the central body surface to a rib on a neighbouring process. A precingular (3") archaeopyle is typically developed. Holotype: Hystrichosphaeridium readei Davey et Williams 1966, p. 64, 65, pl. 6, fig. 3, slide PF 3030 (2). Lower Chalk, Geological Survey Borehole, Fetcham Mill, Surrey, at 210 m depth. Upper Cretaceous (Cenomanian),
England.
Figured specimen: MPK 950, Loffre Borehole, Nord, France at 22.5 m depth; Senonian.
Dimensions (in Ám): Holotype Range
Central body diameter 41 x 45 31-54
Length of processes 23-29 20-35
Description, Davey and Verdier, 1976, p. 314: Kleithriasphaeridium readei
The processes are arranged in a circular manner around the cyst but it is difficult to assign a particular process to a definite reflected plate. If present, the one or two sulcal processes are very narrow and can aid in cyst orientation; if absent, the sulcus may be distinguished as a large "bald" area. It is extremely rare to find a well orientated specimen, which clearly shows the archaeopyle shape, and this has led to confusion as to its position. However, it is pentagonal, with the longest side being along the cingular margin, and squat--its height being approximately equal to its width. Several specimens have been observed with archaeopyles and it is always obvious that no ribs radiate from the processes surrounding the archaeopyle to the archaeopyle margin and, presumably, to the third precingular process. Another feature to aid orientation is that two of the apical processes may be linked medially. The antapical process is not distinctive. Remarks: K. readei occupies a somewhat intermediary position between K loffrensis sp. nov. and K corrugatum Davey (1974). K. readei may be derived *om the latter species by a reduction in the number of ribs to a few, strongly developed ones; also, in both species, two of the apical processes are often linked medially by a septum.
synonyms:
?1940 Hystrichosphaeridium salpingophorum Deflandre, in Lejeune-Carpentier, p. 219,
text-fig. 7.
?1940 Hystrichosphaeridium tubiferum (Ehrenberg) DeMandre, in Lejeune-Carpentier,
p. 218, text-fig. 5.
1966 Hystrichosphaeridium readei Davey et Williams, p. 64, 65, pl. 6, fig. 3.
1969 Hystrichosphaeridium readei Davey et Williams, in Davey, p. 144.
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Originally Hystrichosphaeridium, subsequently (and now) Kleithriasphaeridium.
Holotype: Davey and Williams, 1966, pl.6, fig.3
Locus typicus: Fetcham Mill, England
Stratum typicum: Cenomanian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Kleithriasphaeridium readei (Davey and Williams, 1966b) Davey and Verdier, 1976, emend. Davey and Verdier, 1976. According to Davey and Verdier (1976, p.314), this species has a spherical to subspherical smooth-walled cyst and possesses one tubular process per plate. Processes slightly fibrous, tubiform and are open distally, terminating with a spiny to secate margin. They do not vary much in width except to become narrow when they are sulcal. The processes have three or four thickenings or ribs extending along their length. Each rib continues onto and over the central body surface to a rib on a neighbouring process. Archeopyle precingular. Size: central body diameter 31-54 µm, process length 20-35 µm.
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Original diagnosis: Davey and Williams, 1966, p. 64: Hystrichosphaeridium readei
Spherical to subspherical central body composed of smooth endophragm and periphragm. Processes, composed of the latter, slightly fibrous, cylindrical and open. Larger processes with two thickenings of periphragm extending along their length over surface of central body and joining up with similar thickenings from neighbouring processes. Processes varying in width and expanding distally, terminating in fairly complicated aculeate or secate margin. Apical archaeopyle usually present.
Dimensions: holotype: diameter of central body 41 by 45 Ám, length of processes 23-29 Ám, number of processes 24. Range: diameter of central body 31-54 Ám, length of processes 20-35 Ám.
Original description: Davey and Williams, 1966, p. 64: Hystrichosphaeridium readei
The most characteristic feature of this species is the presence of thickenings or ribs in the periphragm. These ribs are close together near the distal end of the process and gradually diverge proximally, before separating completely on the surface of the central body, each rib passing to a different neighbouring process. Thus triangular and polygonal networks are seen on the surface of the central body.
The sulcal processes are usually noticeably finer than the others and are very occasionally joined by septa, as seen in the holotype. The septa are probably modified ribs. An apical archaeopyle is usually present. The number of processes in the specimens observed varied between 23 and 27. The reflected tabulation is difficult to determine but it is probably comparable to H. tllbiferum i.e. 4', 6", 6c, 5''', 1p, 1'''' and xs.
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Emended diagnosis: Davey and Verdier 1976, p. 314: Kleithriasphaeridium readei
The cyst is spherical to subspherical, smooth-walled and possesses one tubular process per reflected plate area. The processes are slightly fibrous, tubiform and are open distally terminating with a spiny to secate margin; they do not usually vary very much in width except to become narrow when they are present in the sulcal region. The processes have three or four thickenings or ribs extending along their length. Each rib continues onto and over the central body surface to a rib on a neighbouring process. A precingular (3") archaeopyle is typically developed. Holotype: Hystrichosphaeridium readei Davey et Williams 1966, p. 64, 65, pl. 6, fig. 3, slide PF 3030 (2). Lower Chalk, Geological Survey Borehole, Fetcham Mill, Surrey, at 210 m depth. Upper Cretaceous (Cenomanian),
England.
Figured specimen: MPK 950, Loffre Borehole, Nord, France at 22.5 m depth; Senonian.
Dimensions (in Ám): Holotype Range
Central body diameter 41 x 45 31-54
Length of processes 23-29 20-35
Description, Davey and Verdier, 1976, p. 314: Kleithriasphaeridium readei
The processes are arranged in a circular manner around the cyst but it is difficult to assign a particular process to a definite reflected plate. If present, the one or two sulcal processes are very narrow and can aid in cyst orientation; if absent, the sulcus may be distinguished as a large "bald" area. It is extremely rare to find a well orientated specimen, which clearly shows the archaeopyle shape, and this has led to confusion as to its position. However, it is pentagonal, with the longest side being along the cingular margin, and squat--its height being approximately equal to its width. Several specimens have been observed with archaeopyles and it is always obvious that no ribs radiate from the processes surrounding the archaeopyle to the archaeopyle margin and, presumably, to the third precingular process. Another feature to aid orientation is that two of the apical processes may be linked medially. The antapical process is not distinctive. Remarks: K. readei occupies a somewhat intermediary position between K loffrensis sp. nov. and K corrugatum Davey (1974). K. readei may be derived *om the latter species by a reduction in the number of ribs to a few, strongly developed ones; also, in both species, two of the apical processes are often linked medially by a septum.
synonyms:
?1940 Hystrichosphaeridium salpingophorum Deflandre, in Lejeune-Carpentier, p. 219,
text-fig. 7.
?1940 Hystrichosphaeridium tubiferum (Ehrenberg) DeMandre, in Lejeune-Carpentier,
p. 218, text-fig. 5.
1966 Hystrichosphaeridium readei Davey et Williams, p. 64, 65, pl. 6, fig. 3.
1969 Hystrichosphaeridium readei Davey et Williams, in Davey, p. 144.
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