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Hystrichosphaeridium laevigatum
Hystrichosphaeridium laevigatum (Lister, 1970) Eisenack and Kjellstr÷m, 1975
Now Dilatisphaera. Originally (and now) Dilatisphaera, subsequently Hystrichosphaeridium.
Cramer and Diez, 1979, and Fensome et al., 1990, retained this species in Dilatisphaera Lister, 1970.
Holotype: Lister, 1970, pl.6, fig.10
Locus typicus: NW of Upper Dinchope, Shropshire, England
Stratum typicum: Wenlock, Silurian
Original diagnosis: Lister, 1970, p.66
Vesicle hollow, smooth, more or less spherical; processes few in number, variable in length from 0.4 - 1.5 times vesicle diameter, broad, thin-walled, smooth, hollow, tubiform and proximally closed; distally the processes may flare slightly and have a serrated margin or sometimes rounded terminations; the process tips are invariably open. Excystment suture conspicuous, apical, pentagonal in outline; operculum possesses a single plate-centred process.
Dimensions: Vesicle diameter = 11 - 21 µm; process length = 7 - 21 (14) µm; number of processes = 3 - 11 (6); (20 specimens measured).
Now Dilatisphaera. Originally (and now) Dilatisphaera, subsequently Hystrichosphaeridium.
Cramer and Diez, 1979, and Fensome et al., 1990, retained this species in Dilatisphaera Lister, 1970.
Holotype: Lister, 1970, pl.6, fig.10
Locus typicus: NW of Upper Dinchope, Shropshire, England
Stratum typicum: Wenlock, Silurian
Original diagnosis: Lister, 1970, p.66
Vesicle hollow, smooth, more or less spherical; processes few in number, variable in length from 0.4 - 1.5 times vesicle diameter, broad, thin-walled, smooth, hollow, tubiform and proximally closed; distally the processes may flare slightly and have a serrated margin or sometimes rounded terminations; the process tips are invariably open. Excystment suture conspicuous, apical, pentagonal in outline; operculum possesses a single plate-centred process.
Dimensions: Vesicle diameter = 11 - 21 µm; process length = 7 - 21 (14) µm; number of processes = 3 - 11 (6); (20 specimens measured).