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Kleithriasphaeridium fasciatum
Kleithriasphaeridium fasciatum (Davey and Williams, 1966) Davey, 1974
Originally Cordosphaeridium?, subsequently (and now) Kleithriasphaeridium.
Holotype: Davey and Williams, 1966, pl.7, figs.5
Locus typicus: Heslerton, England
Stratum typicum: Barremian
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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 fasciatum (Davey and Williams, 1966b) Davey, 1974 is spherical to subspherical with fibrous periphragm and reticulate endophragm. Processes smooth or slightly fibrous, short, wide and tubiform always hollow and denticulate distally. There are 18-20 processes. Size: diameter of central body 35-47 µm, length of processes 12-25 µm.
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Original diagnosis: Davey and Williams, 1966, p. 90: Cordosphaeridium fasciatum
Spherical to sub-spherical central body composed of reticulate endophragm of fibrous periphragm. Processes, composed of periphagrm, smooth or slightly fibrous, short, wide and tubiform, always hollow and denticulate distally.
Dimensions: holotype: diameter of central body 40 by 40 Ám, length of processes 11-16 Ám, number of processes 19. Range: diameter of central body 35-47 Ám, length of processes 12-25 Ám.
Original description: Davey and Williams, 1966, p. 90-91: Cordosphaeridium fasciatum
From the base of each process, thickenings of the periphragm radiate over the surface of the central body joining together with similar thickenings from neighbouring processes. The reticulate nature of the endophragm can sometimes be observed where the periphragm thins midway between processes and also at the bases of the processes when one is able to view directly down the centre of a vertical process (Pl. 7, fig. 6). The processes have parallel or sub-parallel sides throughout their length. There are 18 to 20 processes, an apical archaeopyle usually being present. The shape and form of the archaeopyle is difficult to determine and a detached apical region has not, as yet, been observed. However the archaeopyle is thought to be haplotabular and the spines to have an inferred reflected tabulation of 1', 6", 6c, 5''', 1'''' and 0-2s.
Affinities:
Davey and Williams, 1966, p. 91: Cordosphaeridium fasciatum
The short, wide tabular processes differentiate this species from ?C. eoinodes (Eisenack) and the nature of the periphragm on the central body is probably different although this was not commented on in the original diagnosis or description. The nature of the periphragm on the surface of the central body and when composing the processes of Hystrichosphaeridium radiculatum and H. mantelli is very similar to C. fasciatum perhaps indicating a relationship between the three species. Each form possesses a distinctive type of process and the two forms of Hystrichosphaeridium have a greater number of processes than does C. fasciatum. The type of archaeopyle is a very important factor in determining the above relationships but unfortunately the exact type of archaeopyle has not been determined as yet.
Originally Cordosphaeridium?, subsequently (and now) Kleithriasphaeridium.
Holotype: Davey and Williams, 1966, pl.7, figs.5
Locus typicus: Heslerton, England
Stratum typicum: Barremian
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Kleithriasphaeridium fasciatum (Davey and Williams, 1966b) Davey, 1974 is spherical to subspherical with fibrous periphragm and reticulate endophragm. Processes smooth or slightly fibrous, short, wide and tubiform always hollow and denticulate distally. There are 18-20 processes. Size: diameter of central body 35-47 µm, length of processes 12-25 µm.
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Original diagnosis: Davey and Williams, 1966, p. 90: Cordosphaeridium fasciatum
Spherical to sub-spherical central body composed of reticulate endophragm of fibrous periphragm. Processes, composed of periphagrm, smooth or slightly fibrous, short, wide and tubiform, always hollow and denticulate distally.
Dimensions: holotype: diameter of central body 40 by 40 Ám, length of processes 11-16 Ám, number of processes 19. Range: diameter of central body 35-47 Ám, length of processes 12-25 Ám.
Original description: Davey and Williams, 1966, p. 90-91: Cordosphaeridium fasciatum
From the base of each process, thickenings of the periphragm radiate over the surface of the central body joining together with similar thickenings from neighbouring processes. The reticulate nature of the endophragm can sometimes be observed where the periphragm thins midway between processes and also at the bases of the processes when one is able to view directly down the centre of a vertical process (Pl. 7, fig. 6). The processes have parallel or sub-parallel sides throughout their length. There are 18 to 20 processes, an apical archaeopyle usually being present. The shape and form of the archaeopyle is difficult to determine and a detached apical region has not, as yet, been observed. However the archaeopyle is thought to be haplotabular and the spines to have an inferred reflected tabulation of 1', 6", 6c, 5''', 1'''' and 0-2s.
Affinities:
Davey and Williams, 1966, p. 91: Cordosphaeridium fasciatum
The short, wide tabular processes differentiate this species from ?C. eoinodes (Eisenack) and the nature of the periphragm on the central body is probably different although this was not commented on in the original diagnosis or description. The nature of the periphragm on the surface of the central body and when composing the processes of Hystrichosphaeridium radiculatum and H. mantelli is very similar to C. fasciatum perhaps indicating a relationship between the three species. Each form possesses a distinctive type of process and the two forms of Hystrichosphaeridium have a greater number of processes than does C. fasciatum. The type of archaeopyle is a very important factor in determining the above relationships but unfortunately the exact type of archaeopyle has not been determined as yet.