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Hystrichokolpoma unispinum
Hystrichokolpoma unispinum Williams and Downie, 1966a, p.179-180, pl.17, figs.6-7. Holotype: Williams and Downie, 1966a, pl.17, fig.7; Bujak et al., 1980, pl.3, figs.1-3; Fauconnier and Masure, 2004, pl.42, figs.4-6. Davey and Verdier (1976, p.316) considered this species to be a possible taxonomic synonym of Hystrichosphaeridium (now Florentinia) deanei, the type material of Hystrichokolpoma unispinum representing possibly reworked Cretaceous specimens. Age: Early Eocene.
Original diagnosis: Williams and Downie, 1966, p. 179
Central body sub-spherical with thin smooth endophragm, continuous beneath processes, and thin smooth periphragm. Processes formed from periphragm and of two types, broad tapering lagenate, and buccinate more slender processes. Reflected tabulation of 4", 6", 6c, 5""", 1p, 1"""" and at least 5s. Each cingular plate possessing only one process.
Dimensions: Holotype: diameter of central body 39 by 43 Ám. Length of broad processes up to 29 Ám, width up to 21 Ám. Slender processes, length up to 26 Ám, width up to 5 Ám. Range of dimensions observed: diameter of central body 39-51 Ám. Length of broad processes 21-29 Ám, breadth up to 21 Ám. Equatorial processes, length 18-26 Ám, breadth up to 5 Ám.
Original description: Williams and Downie, 1966, p. 180
The tabulation of H. unispinum is well shown in two specimens from the London Clay. There are four apical plates, 1" being smaller than the other three. The apical processes are tapering, open distally with a serrate or undulose margin. Five of the precingular plates and processes are equal in size, the other, plate 6", is smaller, more closely approaching the anterior sulcal plate. The equatorial plates each possess one process. The postcingulars are as in H. eisenacki, with plate 1""" being reduced compared to the other four. The process of the posterior intercalary plate is small and the antapical plate is marked by a longer than average process.
The broad processes all appear open distally and may have small tubular branches. The equatorial processes are broader than in other species of Hystrichokolpoma and are tubiform or buccinate with serrate or undulose distal margins. A few have perforations in the wall, irregular in position. The processes may occasionally be branched. The posterior sulcal processes are slender and short with digitate endings which may be open or closed.
Affinities:
Williams and Downie, 1966, p. 180: The presence of one process only on each cingular plate readily distinguishes H. unispinum from other species of Hystrichokolpoma.
Original diagnosis: Williams and Downie, 1966, p. 179
Central body sub-spherical with thin smooth endophragm, continuous beneath processes, and thin smooth periphragm. Processes formed from periphragm and of two types, broad tapering lagenate, and buccinate more slender processes. Reflected tabulation of 4", 6", 6c, 5""", 1p, 1"""" and at least 5s. Each cingular plate possessing only one process.
Dimensions: Holotype: diameter of central body 39 by 43 Ám. Length of broad processes up to 29 Ám, width up to 21 Ám. Slender processes, length up to 26 Ám, width up to 5 Ám. Range of dimensions observed: diameter of central body 39-51 Ám. Length of broad processes 21-29 Ám, breadth up to 21 Ám. Equatorial processes, length 18-26 Ám, breadth up to 5 Ám.
Original description: Williams and Downie, 1966, p. 180
The tabulation of H. unispinum is well shown in two specimens from the London Clay. There are four apical plates, 1" being smaller than the other three. The apical processes are tapering, open distally with a serrate or undulose margin. Five of the precingular plates and processes are equal in size, the other, plate 6", is smaller, more closely approaching the anterior sulcal plate. The equatorial plates each possess one process. The postcingulars are as in H. eisenacki, with plate 1""" being reduced compared to the other four. The process of the posterior intercalary plate is small and the antapical plate is marked by a longer than average process.
The broad processes all appear open distally and may have small tubular branches. The equatorial processes are broader than in other species of Hystrichokolpoma and are tubiform or buccinate with serrate or undulose distal margins. A few have perforations in the wall, irregular in position. The processes may occasionally be branched. The posterior sulcal processes are slender and short with digitate endings which may be open or closed.
Affinities:
Williams and Downie, 1966, p. 180: The presence of one process only on each cingular plate readily distinguishes H. unispinum from other species of Hystrichokolpoma.