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Hystrichosphaeridium bowerbankii

Hystrichosphaeridium bowerbankii Davey and Williams 1966

Holotype: Davey and Williams, 1966b, pl.8, fig.4; Fauconnier and Masure, 2004, pl.43, fig.8.
Locus typicus: Fetcham Mill, Surrey, 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.

Hystrichosphaeridium bowerbankii Davey and Williams, 1966b. According to Davey and Williams (1966b, p.69), this species has an ovoidal to elongate central body with smooth surface. Processes thin-walled, tubular, open distally, sometimes widening considerably at the base, and greater than half the central body diameter in length. They terminate in a number of orthogonal or recurved spines. The distal spines are 5 to 7 in number and up to 6 µm long. The processes are cylindrical for most of their length, 2.5-3 µm wide and expand slightly distally to about 4u before giving rise to spines. They may widen up to 10 µm at their base. Tabulation: (4'), 6", 6c, 5"’, 1p, 1"”, ca 5s. Size:overall diameter 60-85 µm, diameter of central body 29-40 µm, length of processes 21-26 µm.
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Original diagnosis: Davey and Williams, 1966, p. 69
Ovoidal to elongate central body with smooth surface. Processes thin-walled, tubular, open distally, sometimes widening considerably at their base, and greater than half the central body diameter in length. They terminate in a number of orthogonal or recurved spines. Apical archaeopyle usually present.
Dimensions: holotype: overall diameter 85 by 78 Ám, diameter of central body 39 by 29 Ám, length of processes 24-26 Ám, number of processes 24. Range: overall diameter 60-85 Ám, diameter of central body 29-40 Ám, length of processes 21-26 Ám.

Original description: Davey and Williams, 1966, p.69-70
The central body is characteristically ovoidal to elongate. The tubular processes are thin-walled and usually curved or bent to some extent. The distal spines are 5 to 7 in number and are up to 6 Ám in length. The processes are cylindrical for most of their length, 2.5 to 3 Ám wide and expand slightly distally to about 4 Ám before giving rise to spines. Proximally the processes sometimes widen considerably and may measure up to 10 Ám at their contact with the central body and often show notacible basal wrinkels. An apical archaeopyle always appears to be present. The tabulation reflected by the processes is: (4'), 6'', 6c, 5''', 1p, 1'''' and about 5s.

Affinities:
Davey and Williams, 1966, p. 70: H. bowerbankii differs from H. recurvatum (White) in being smaller and having wider tubular processes. It is rather similar to H.sheppeyense but the form of the central body is more or less elongate; the processes are wider, especially at their base, and have a much thinner wall.
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