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Adnatosphaeridium tubulosum
Adnatosphaeridium tubulosum sp. nov., Vieira and Mahdi, 2021
Holotype: Plate 1, figures 1 and 2, Vieira and Mahdi, 2021
Type locality: Møre Basin (Norway)
Stratigraphic extent: Late Cretaceous, Campanian to early Maastrichtian
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Original description: Vieira and Mahdi, 2021:
Diagnosis:
Proximochorate to scholochorate, with rounded to sub-rounded two-layered intratabulate dinoflagellate cyst. The processes are intertabular, slender, hollow, extremely variable in shape and size and widen distally to form complex trabeculae that link adjacent processes. The antapical processes are usually longer than the apical ones.
Description:
Proximochorate to scholochorate two-layered intratabular gonyaulacoid dinoflagellate cyst of large size.
Central body dorso-ventrally compressed. Rounded to sub-rounded, composed of thin, smooth endophragm and slightly thicker with scabrate/punctuate periphragm.
Cingulum is indistinguishable and occasionally indicated by intratabular tubiform processes.
The archaeopyle is apical, operculum free.
The processes are long, well-developed, smooth to minutely granulate, hollow intratabular variable in shape and size, arising from the periphragm. These processes are expanded distally and have a distinctive ragged appearance to form a trabecular complex linking them to the adjacent processes. All the processes are in this way linked by the trabeculae. In most cysts it was possible to observe that the antapical processes are usually larger and longer than the apical processes.
Dimensions:
Central body length 31 (36) 40 µm, width 34 (38) 40 µm, with process length 66 (74) 86 µm, width 70 (76) 85 lµm.
15 specimens measured
Comparison and remarks:
This new species was reported by McIntyre (1974, pl. 10, figs 7–8) as Hystrichosphaeridium sp. 3, from Horton River, District of Mackenzie, NWT (the 16B ‘Pale shale zone’ outcrop of Campanian–Maastrichtian age). This species has been assigned to Adnatosphaeridium tubulosum by virtue of its hollow tubiform processes which are expanded distally with a distinctive ragged appearance. Adnatosphaeridium sp. McIntyre 1974 (pl. 10, fig. 10 and pl. 11, fig. 1) differs in having what looks like solid processes. No formal diagnoses or descriptions of those species were given by McIntyre (1974). Adnatosphaeridium tubulosum sp. nov. has been observed by various biostratigraphic contractors and oil companies from several wells in northwest Europe under the informal name Hystrichosphaeridium sp. 3, published by McIntyre (1974, pl. 10, figs 7–8).
Holotype: Plate 1, figures 1 and 2, Vieira and Mahdi, 2021
Type locality: Møre Basin (Norway)
Stratigraphic extent: Late Cretaceous, Campanian to early Maastrichtian
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Original description: Vieira and Mahdi, 2021:
Diagnosis:
Proximochorate to scholochorate, with rounded to sub-rounded two-layered intratabulate dinoflagellate cyst. The processes are intertabular, slender, hollow, extremely variable in shape and size and widen distally to form complex trabeculae that link adjacent processes. The antapical processes are usually longer than the apical ones.
Description:
Proximochorate to scholochorate two-layered intratabular gonyaulacoid dinoflagellate cyst of large size.
Central body dorso-ventrally compressed. Rounded to sub-rounded, composed of thin, smooth endophragm and slightly thicker with scabrate/punctuate periphragm.
Cingulum is indistinguishable and occasionally indicated by intratabular tubiform processes.
The archaeopyle is apical, operculum free.
The processes are long, well-developed, smooth to minutely granulate, hollow intratabular variable in shape and size, arising from the periphragm. These processes are expanded distally and have a distinctive ragged appearance to form a trabecular complex linking them to the adjacent processes. All the processes are in this way linked by the trabeculae. In most cysts it was possible to observe that the antapical processes are usually larger and longer than the apical processes.
Dimensions:
Central body length 31 (36) 40 µm, width 34 (38) 40 µm, with process length 66 (74) 86 µm, width 70 (76) 85 lµm.
15 specimens measured
Comparison and remarks:
This new species was reported by McIntyre (1974, pl. 10, figs 7–8) as Hystrichosphaeridium sp. 3, from Horton River, District of Mackenzie, NWT (the 16B ‘Pale shale zone’ outcrop of Campanian–Maastrichtian age). This species has been assigned to Adnatosphaeridium tubulosum by virtue of its hollow tubiform processes which are expanded distally with a distinctive ragged appearance. Adnatosphaeridium sp. McIntyre 1974 (pl. 10, fig. 10 and pl. 11, fig. 1) differs in having what looks like solid processes. No formal diagnoses or descriptions of those species were given by McIntyre (1974). Adnatosphaeridium tubulosum sp. nov. has been observed by various biostratigraphic contractors and oil companies from several wells in northwest Europe under the informal name Hystrichosphaeridium sp. 3, published by McIntyre (1974, pl. 10, figs 7–8).