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Systematophora vetuscula

Systematophora vetuscula (Davey, 1974) Duxbury, 1977

Now Nexosispinum. Originally Adnatosphaeridium, subsequently Systematophora, thirdly (and now) Nexosispinum, fourthly Kiokansium.

Holotype: Davey 1974, pl.1, fig.2
Locus typicus: Speeton, England
Stratum typicum: Barremian

Original diagnosis: Davey, 1974, p.45: Adnatosphaeridium vetusculum
The cyst is spherical to subspherical, smooth and bears numerous complex rigid, solid processes. Process alignment is not apparent. All the processes on a specimen are generally of approximately the same width. Some are simple but more usually one anastomoses with its neighbour or neighbours either proximately, medially or distally. they terminate distally with a simple or complex bifurcation. The archaeopyle appears to be apical with the operculum sometimes remaining attached.
Dimensions: Central body diameter - range - 37(43.5)57 µm. Process length 8(11)17 µm.

Original description: Davey, 1974, p.45: Adnatosphaeridium vetusculum
Proximally the processes are usually about 1µm wide; distally they assume various complex configurations. Rarely they are simple with a short distal bifucation; more often one anastomoses with its neighbour immediately after leaving the central body surface and bifurcates once or twice distally, or anastomosis of two or more processes take place medially or distally. In the last case bifurcations are still present distally together occasionally with very fine tapering spines which may be blunted distally or terminate with a minute bifurcation.

Supplemental description: Duxbury, 1977, p. 51
A small chorate cyst. The main body is sub-spherical and finely granular. The periphragm is produced into numerous short, distally pointed elements which appear to be inserted in groups with the elements forming "process complexes". That is, the numerous processes represent a relatively small number of larger, hollow processes. Commonly, the short, spinose elements are connected by trabeculae at right angles to their length, usually near their distal extremes but this may occur at any point along their length. The archeopyle is apical and formed by the detachment of the apical plates along a distinctly zig-zag line.
Observed Dimensions: Complete Specimens--Overall 65(62)58 x 59(57)55 µm.
Archeopyle Formed --Overall 64(60)57 x 69(67)65 µm.
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