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Impletosphaeridium clavulum
Impletosphaeridium clavulum (Davey, 1969) Islam, 1993
Originally Cleistosphaeridium polypes var. clavulum, subsequently Cleistosphaeridium polypes subsp. clavulum, thirdly Impletosphaeridium polypes subsp. clavulum, fourthly Bacchidinium polypes subsp. clavulum, fifthly Cleistosphaeridium clavulum, sixthly Impletosphaeridium clavulum, seventhly (and now) Impletosphaeridium? clavulum. Questionable assignment: Peyrot (2011, p.293).
Holotype: Davey, 1969a, pl.6, fig.9; Fauconnier and Masure, 2004, pl.50, fig.1.
Age: 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.
Impletosphaeridium clavulum (Davey, 1969a) Islam, 1993, has fine capitate processes. Processes terminating with fine spines are rare. The terminal bulge is flattened and resembles the head of a pin. Size: diameter of central body 29-39 µm, maximum length of processes 13-15 µm.
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Original diagnosis: Davey 1969a, p. 154, 155: Cleistosphaeridium polypes var. clavulum
A variety of C. polypes possessing fine, capitate processes. Processes terminating with fine spines are extremely rare.
Dimensions: Type: diameter of central body 29 by 32µ, length of processes 12-13µ. Range: diameter of central body 29 (31.5) 39µ, maximum length of processes 13 (I4.7) I5µ. Numbers of specimens measured: 10.
Remarks: C. polypes var. clavulum differs from C. polypes in that the processes are capitate, the terminal bulge being flattened and resembling the hcad of a pin. Two specimens have been observed each possessing one process of the type characteristic of C. polypes thus indicating a relationship between the two forms. C. polypes probably evolved from this variety, spiny processes replacing the capitate ones.
Occurence: This variety has only been recorded from the lowermost Cenomanian samples at Fetcham Mill (sample FM 840) and Compton Bay (samplc CB I). It was previously recorded by Cookson & Hughes (I964) from the Upper Albian--basal Cenomanian of England and so appears to be of stratigraphic importance in England for indicating the base of this stage. It does not occur in the lowermost sample from Escalles.
Originally Cleistosphaeridium polypes var. clavulum, subsequently Cleistosphaeridium polypes subsp. clavulum, thirdly Impletosphaeridium polypes subsp. clavulum, fourthly Bacchidinium polypes subsp. clavulum, fifthly Cleistosphaeridium clavulum, sixthly Impletosphaeridium clavulum, seventhly (and now) Impletosphaeridium? clavulum. Questionable assignment: Peyrot (2011, p.293).
Holotype: Davey, 1969a, pl.6, fig.9; Fauconnier and Masure, 2004, pl.50, fig.1.
Age: Cenomanian.
--------------------------------------------------
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.
Impletosphaeridium clavulum (Davey, 1969a) Islam, 1993, has fine capitate processes. Processes terminating with fine spines are rare. The terminal bulge is flattened and resembles the head of a pin. Size: diameter of central body 29-39 µm, maximum length of processes 13-15 µm.
--------------------------------------------------
Original diagnosis: Davey 1969a, p. 154, 155: Cleistosphaeridium polypes var. clavulum
A variety of C. polypes possessing fine, capitate processes. Processes terminating with fine spines are extremely rare.
Dimensions: Type: diameter of central body 29 by 32µ, length of processes 12-13µ. Range: diameter of central body 29 (31.5) 39µ, maximum length of processes 13 (I4.7) I5µ. Numbers of specimens measured: 10.
Remarks: C. polypes var. clavulum differs from C. polypes in that the processes are capitate, the terminal bulge being flattened and resembling the hcad of a pin. Two specimens have been observed each possessing one process of the type characteristic of C. polypes thus indicating a relationship between the two forms. C. polypes probably evolved from this variety, spiny processes replacing the capitate ones.
Occurence: This variety has only been recorded from the lowermost Cenomanian samples at Fetcham Mill (sample FM 840) and Compton Bay (samplc CB I). It was previously recorded by Cookson & Hughes (I964) from the Upper Albian--basal Cenomanian of England and so appears to be of stratigraphic importance in England for indicating the base of this stage. It does not occur in the lowermost sample from Escalles.