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Cordosphaeridium exilimurum
Cordosphaeridium exilimurum, Davey and Williams, 1966
Originally Cordosphaeridium, subsequently Hystrichosphaerina?, thirdly Tityrosphaeridium?.
Taxonomic senior synonym: Cordosphaeridium fibrospinosum, according to Fensome et al. (2009, p.23).
Tax. sr. synonym of Achomosphaera (subsequently Cordosphaeridium) valianta Sah et al., 1970, according to Jain, 1982. Sarjeant, 1981, provisionally transferred this species to Hystrichosphaerina Alberti, 1961. Lentin and Williams, 1985, retained it in Cordosphaeridium. Jain and Garg, 1986, provisionally transferred the species to Tityrosphaeridium Sarjeant, 1981. Lentin and Williams, 1989, retained it in Cordosphaeridium.
Holotype: Davey and Williams, 1966, pl.11, Bujak et al., 1980, fig.2; pl.7, figs.4-5
Locus typicus: London Clay, Isle of Whight, England
Stratum typicum: Early Eocene
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Original description: Davey and Williams, 1966, p. 87-88
Diagnosis:
Ovoidal central body, composed of thin, smooth or slightly granular endophragm with fine fibrils of periphragm running over surface.
Processes tubiform or buccinate, of variable width, and rarely latispinous, distally open with serrate or undulose margin. Wall of processes thin and often fenestrate.
Description:
Haplotabular archaeopyle and tabulation characteristic of the genus Cordosphaeridium.
The number of processes per plate area is one, but occasionally a fine subsidiary process may be present. Fine processes also occur in the sulcal region. Both the endophragm and periphragm are extremely thin, especially the latter when forming the processes. The wall of the processes is smooth or fibrous; in the former the fibrils are only faintly developed. Whether or not the processes are always fenestrate is difficult to determine, even at high magnification, on account of the thinness of the periphragm. The processes rarely exceed half the diameter of the central body; they are up to 10 µm wide meridionally and distally extremely expanded. Adjacent processes are occasionally united distally.
Dimensions:
holotype: diameter of central body 44x54 µm, length of processes 18-26 µm. Range: diameter of central body 44-98 µm, length of processes 16-42 µm.
Affinities:
No other described species possesses fine, often perforate processes with an apical haplotabular archaeopyle and tabulation 1", 6", 6c, 6""", 1"""" and a variable number of sulcal processes. ?C. cantharellum (Brosius 1963) is similar in general form but possesses stronger, more cylindrical processes which are never perforate or united distally, and often have a recurved distal margin.
Originally Cordosphaeridium, subsequently Hystrichosphaerina?, thirdly Tityrosphaeridium?.
Taxonomic senior synonym: Cordosphaeridium fibrospinosum, according to Fensome et al. (2009, p.23).
Tax. sr. synonym of Achomosphaera (subsequently Cordosphaeridium) valianta Sah et al., 1970, according to Jain, 1982. Sarjeant, 1981, provisionally transferred this species to Hystrichosphaerina Alberti, 1961. Lentin and Williams, 1985, retained it in Cordosphaeridium. Jain and Garg, 1986, provisionally transferred the species to Tityrosphaeridium Sarjeant, 1981. Lentin and Williams, 1989, retained it in Cordosphaeridium.
Holotype: Davey and Williams, 1966, pl.11, Bujak et al., 1980, fig.2; pl.7, figs.4-5
Locus typicus: London Clay, Isle of Whight, England
Stratum typicum: Early Eocene
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Original description: Davey and Williams, 1966, p. 87-88
Diagnosis:
Ovoidal central body, composed of thin, smooth or slightly granular endophragm with fine fibrils of periphragm running over surface.
Processes tubiform or buccinate, of variable width, and rarely latispinous, distally open with serrate or undulose margin. Wall of processes thin and often fenestrate.
Description:
Haplotabular archaeopyle and tabulation characteristic of the genus Cordosphaeridium.
The number of processes per plate area is one, but occasionally a fine subsidiary process may be present. Fine processes also occur in the sulcal region. Both the endophragm and periphragm are extremely thin, especially the latter when forming the processes. The wall of the processes is smooth or fibrous; in the former the fibrils are only faintly developed. Whether or not the processes are always fenestrate is difficult to determine, even at high magnification, on account of the thinness of the periphragm. The processes rarely exceed half the diameter of the central body; they are up to 10 µm wide meridionally and distally extremely expanded. Adjacent processes are occasionally united distally.
Dimensions:
holotype: diameter of central body 44x54 µm, length of processes 18-26 µm. Range: diameter of central body 44-98 µm, length of processes 16-42 µm.
Affinities:
No other described species possesses fine, often perforate processes with an apical haplotabular archaeopyle and tabulation 1", 6", 6c, 6""", 1"""" and a variable number of sulcal processes. ?C. cantharellum (Brosius 1963) is similar in general form but possesses stronger, more cylindrical processes which are never perforate or united distally, and often have a recurved distal margin.