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Nexosispinum hesperum
Nexosispinum hesperum Davey, 1979
Originally (and now) Nexosispinum, subsequently Kiokansium.
Stover and Williams, 1987, transferred this species to Kiokansium Stover and Evitt, 1978. Prössl, 1990, retained it in Nexosispinum.
Holotype: Davey 1979b: Pl. 6, fig. 5
Locus typicus: DSDP Leg 48, Hole 402A, northern Bay of Biscay
Stratum typicum: Albian.
Age: Aptian-Albian
Original diagnosis: Davey 1979b, p. 558
A species of Nexosispinum possessing a thin, lightly punctate or intraperforate wall. Simple processes are common; others anastomoze in an uncomplicated manner with one or two neighboring processes. The anastomozing is generally proximal or medial. The processes are either irregularly arranged over the cyst surface or they sometimes occur in small clumps or alignments. Distally, they are generally capitate or briefly bifurcate. An archeopyle is normally present.
Dimensions: Holotype Range
Endocyst diameter 40 x 41µm 38 (47) 69 µm
Process length 6-7 µm 6-9 µm
Description: Davey 1979b, p. 558
The thickness of the cyst wall and the processes are both about 0.5µm. The exact shape of the archeopyle is normally very difficult to discern because of cyst distortion: occasionally the operculum remains in position.
Remarks: Davey 1979b, p. 558
N. hesperum sp. nov . differs from N. vetusculum comb. nov. by having a punctate wall and by the processes which are fewer in number, shorter, and less complexly linked. N. vetusculum has not been recorded above the early Barremian of England (Davey, 1974; Duxbury, 1977).
Originally (and now) Nexosispinum, subsequently Kiokansium.
Stover and Williams, 1987, transferred this species to Kiokansium Stover and Evitt, 1978. Prössl, 1990, retained it in Nexosispinum.
Holotype: Davey 1979b: Pl. 6, fig. 5
Locus typicus: DSDP Leg 48, Hole 402A, northern Bay of Biscay
Stratum typicum: Albian.
Age: Aptian-Albian
Original diagnosis: Davey 1979b, p. 558
A species of Nexosispinum possessing a thin, lightly punctate or intraperforate wall. Simple processes are common; others anastomoze in an uncomplicated manner with one or two neighboring processes. The anastomozing is generally proximal or medial. The processes are either irregularly arranged over the cyst surface or they sometimes occur in small clumps or alignments. Distally, they are generally capitate or briefly bifurcate. An archeopyle is normally present.
Dimensions: Holotype Range
Endocyst diameter 40 x 41µm 38 (47) 69 µm
Process length 6-7 µm 6-9 µm
Description: Davey 1979b, p. 558
The thickness of the cyst wall and the processes are both about 0.5µm. The exact shape of the archeopyle is normally very difficult to discern because of cyst distortion: occasionally the operculum remains in position.
Remarks: Davey 1979b, p. 558
N. hesperum sp. nov . differs from N. vetusculum comb. nov. by having a punctate wall and by the processes which are fewer in number, shorter, and less complexly linked. N. vetusculum has not been recorded above the early Barremian of England (Davey, 1974; Duxbury, 1977).