Hystrichosphaeridium simplicispinum Davey and Williams, 1966

Originally Hystrichosphaeridium, subsequently Kleithriasphaeridium.
Tax. jr. synonym of Hystrichosphaeridium (now Kleithriasphaeridium) eoinodes Eisenack, 1968, according to Below, 1982.
Holotype: Davey and Williams, 1966, pl.9,fig.3
Locus typicus: Heslerton, England
Stratum typicum: Middle Barremian

Original diagnosis: Davey and Williams, 1966, p. 59
Spherical central body composed of thin smooth endophragm and periphragm, the latter forming the processes. Processes varying considerably in size and are simple, tubiform, splaying out distally and terminate with denticulate or secate margin. A number of fine sulcal processes. Apical archaeopyle usually present.
Dimensions: holotype: diameter of central body 36 by 43 µm, length of processes
17-26 µm. Number of processes 23, plus 4 fine sulcal processes. Range: diameter of central body 34-57 µm, length of processes 8-31 µm.

Original description: Davey and Williams, 1966, p. 59
The smooth periphragm of the central body and processes is sometimes slightly perforate but more commonly smooth. At the base of each process there is a characteristic thickening of the endophragm, which is here reticulate. Only four well preserved specimens have been observed, the number of wide tubular processes ranging from 22 to 24, with 1 to 6 fine sulcal processes. The antapical process is often distinctly wider than the other processes. The reflected tabulation appears to be comparable to H. tubiferum.

Affinities:
Davey and Williams, 1966, p. 59: In general appearance H. simplicispinum strongly resembles Cordosphaeridium eoinodes but the fibrous periphragm is absent and the number of processes is greater.
The reflected tabulation of H. simplicispinum is probably the same as H. tubiferum,
but they differ in that the processes of the former are considerably more divided and not so expanded distally.