Back
Cleistosphaeridium polypes var. clavulum
Cleistosphaeridium polypes var. clavulum, Davey, 1969
NOW Impletosphaeridium? clavulum. 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.
Holotype: Davey, 1969, pl.6, fig.9
Occurrence: This variety has only been recorded from the lowermost Cenomanian samples at Fetcham Mill (sample FM 840) and Compton Bay (sample 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.
Age: Cenomanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Cleistosphaeridium polypes var. clavulum: [Davey 1969a, p. 154, 155]:
Diagnosis:
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 32 µm, length of processes 12-13 µm.
Range: diameter of central body 29 (31.5) 39 µm, maximum length of processes 13 (14.7) 15 µm. 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 head 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.
NOW Impletosphaeridium? clavulum. 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.
Holotype: Davey, 1969, pl.6, fig.9
Occurrence: This variety has only been recorded from the lowermost Cenomanian samples at Fetcham Mill (sample FM 840) and Compton Bay (sample 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.
Age: Cenomanian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description as Cleistosphaeridium polypes var. clavulum: [Davey 1969a, p. 154, 155]:
Diagnosis:
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 32 µm, length of processes 12-13 µm.
Range: diameter of central body 29 (31.5) 39 µm, maximum length of processes 13 (14.7) 15 µm. 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 head 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.