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Hystrichosphaeridium latirictum
Hystrichosphaeridium? latirictum Davey and Williams, 1966, p.66-67
NOW Minisphaeridium. Originally Hystrichosphaeridium, subsequently Hystrichosphaeridium?, thirdly (and now) Minisphaeridium. Questionable assignment: Bujak et al. (1980, p.46).
Taxonomic junior synonyms: Cordosphaeridium minimum (al. Cordosphaeridium inodes subsp. minimum) according to Fensome et al. (2009, p.44) — the epithet latirictum has priority at specific rank over the epithet minimum; Litosphaeridium? parvum, according to Fensome et al. (2009, p.44).
Holotype: Davey and Williams, 1966, pl.10, fig.8; Bujak et al., 1980, pl.8, figs.4-5
Locus typicus: Enborne, England
Stratum typicum: Early Eocene
Original diagnosis: Davey and Williams, 1966, p. 66
Central body ellipsoidal, with smooth or slightly granular wall up to one-quarter µm thick. Processes slender, tubiform, slightly fibrous, expanding considerably distally. Processes open distally and margin circular or quadrate.
Dimensions: holotype: diameter of central body 18 by 9.5 µm, length of processes 9-12.5 µm breadth of processes up to 2 µm, length of acuminate processes 6-8 µm, number of processes 25 (and two acuminate processes). Range: diameter of central body 11-20 µm, length of processes 6-13 µm.
Original description: Davey and Williams, 1966, p. 67
The processes show a variation in outline and nature of distal margin which can be circularly to ovoidal, serrate, undulose or aculeate. The distal extremities of the processes are usually considerably expanded, up to 13 µm wide. The length of the processes vary from one-third to two-thirds of the diameter of the central body. Besides the tubiform process there is quite often a small number of short, closed processes, as on the holotype. The latter are undoubtedly sulcal processes. An apical archaeopyle is present surrounded by 6 processes, the reflected tabulation probably being that of this genus.
Affinities:
Davey and Williams, 1966, p. 67: The size of H. Iatirictum sp. nov., in combination with the tubiform processes, is quite characteristic. Polysphaeridium paulinae from the Middle Jurassic of France (Valensi I953) is similar in form but smaller with more processes, the processes being not greater than one-third of the diameter of the central body. It is possible that this species may result from misinterpretation of representatives of the genus Stephanelytron: the holotype, kindly lent by Prof. Deflandre for examination (in I962), is at depth in flint and cannot be seen in full detail. Hystrichospheres with tubular processes are not otherwise known from the Middle Jurassic.
NOW Minisphaeridium. Originally Hystrichosphaeridium, subsequently Hystrichosphaeridium?, thirdly (and now) Minisphaeridium. Questionable assignment: Bujak et al. (1980, p.46).
Taxonomic junior synonyms: Cordosphaeridium minimum (al. Cordosphaeridium inodes subsp. minimum) according to Fensome et al. (2009, p.44) — the epithet latirictum has priority at specific rank over the epithet minimum; Litosphaeridium? parvum, according to Fensome et al. (2009, p.44).
Holotype: Davey and Williams, 1966, pl.10, fig.8; Bujak et al., 1980, pl.8, figs.4-5
Locus typicus: Enborne, England
Stratum typicum: Early Eocene
Original diagnosis: Davey and Williams, 1966, p. 66
Central body ellipsoidal, with smooth or slightly granular wall up to one-quarter µm thick. Processes slender, tubiform, slightly fibrous, expanding considerably distally. Processes open distally and margin circular or quadrate.
Dimensions: holotype: diameter of central body 18 by 9.5 µm, length of processes 9-12.5 µm breadth of processes up to 2 µm, length of acuminate processes 6-8 µm, number of processes 25 (and two acuminate processes). Range: diameter of central body 11-20 µm, length of processes 6-13 µm.
Original description: Davey and Williams, 1966, p. 67
The processes show a variation in outline and nature of distal margin which can be circularly to ovoidal, serrate, undulose or aculeate. The distal extremities of the processes are usually considerably expanded, up to 13 µm wide. The length of the processes vary from one-third to two-thirds of the diameter of the central body. Besides the tubiform process there is quite often a small number of short, closed processes, as on the holotype. The latter are undoubtedly sulcal processes. An apical archaeopyle is present surrounded by 6 processes, the reflected tabulation probably being that of this genus.
Affinities:
Davey and Williams, 1966, p. 67: The size of H. Iatirictum sp. nov., in combination with the tubiform processes, is quite characteristic. Polysphaeridium paulinae from the Middle Jurassic of France (Valensi I953) is similar in form but smaller with more processes, the processes being not greater than one-third of the diameter of the central body. It is possible that this species may result from misinterpretation of representatives of the genus Stephanelytron: the holotype, kindly lent by Prof. Deflandre for examination (in I962), is at depth in flint and cannot be seen in full detail. Hystrichospheres with tubular processes are not otherwise known from the Middle Jurassic.