Nannotax3 - ntax_main - Arkhangelskiella cymbiformis

Citation: Arkhangelskiella cymbiformis Vekshina, 1959

Synonyms:

Arkhangelskiella imperfossa Hoffmann 1970 [my interpretation - JRY 2021]
Arkhangelskiella cymbiformis var. NT of Varol 1989.
Discolithus octocentralis Stover (1966) (according to Reinhardt 1967, Hattner & Wise 1980)
Arkhangelskiella paucipunctata Moshkovitz & Osmond 1989 - form with strongly curved coccoliths and few pores.

Variants:

Arkhangelskiella confusa Burnett 1997 = Arkhangellskiella cymbiformis var N of Varol (1989) - form with normal width rim
Arkhangelskiella cymbiformis sensu Burnett 1997 = Arkhangellskiella cymbiformis var NT of Varol (1989) - form with narrow rim

Varol 1989 suggested that three morphotypes could usefully be distinguished within the A. cymbiformis group based on rim width (more/less than 2µm) and thickness (some forms have a thin outer edge to the shield). He termed them varieties N, NT and W (for Narrow, Narrow&Thin, Wide rim). Subsequently, Burnett (1997) separated these as species - A. confusa. A. cymbiformis and A. maastrichtiensis, with slightly modified definitions. Linnert & Mutterlose (2009), however, concluded that only one, morphologically variable species, was present. In particular, they showed that separating the narrow rim width form was of very limited value, even though they studied the time interval during which Varol (1989) recorded it as common.
Linnert & Mutterlose (2009) also suggested that the maastrichtiana morphotype was simply a wide-rimmed variant of cymbiformis, but they did not include the Late Maastrichtian when this form is recorded as being best developed, so this form may still be worth separating.

Varol 1989			Burnett 1987
term		shield width	name	shield width	coccolith size
W	wide shield	>2 µm	maastrichtensis	>1.5 µm	>10 µm
N	narrow shield	confusus< 8 µm
NT	narrow & thin shield	1-1.5 µm	cymbiformis	> 8 µm

Distinguishing features:
Parent taxon (Arkhangelskiella): R-units cover the distal surface, so coccolith appears bright, unicyclic, in LM (although darker towards outer edge); central-area has perforate plate with axial sutures. 4 tiers visible in side view.
This taxon: Large (8-10µm), with a narrow rim (<1.5µm)

Geological Range:
Notes: Linnert & Mutterlose (2009) show that the mean length of Arkhangellskiella specimens is about 6.5-7µm through the Campanain but 8-9 µm in the Maastrichtian - base on a study of DSDP site 390 (Blake Nose, NW Atlantic).
Last occurrence (top): at top of Maastrichtian Stage (100% up, 66Ma, in Danian stage). Data source: Lees & Bown 2005 - consistently present to end Cret
First occurrence (base): at base of UC13 zone (0% up, 84Ma, in Santonian stage). Data source: Burnett 1998 (zonal marker)

References:

Bralower, T. J. & Siesser, W. G. (1992). Cretaceous calcareous nannofossil biostratigraphy of Sites 761, 762, and 763, Exmouth and Wombat Plateaus, northwest Australia. Proceedings of the Ocean Drilling Program, Scientific Results. 122: 529-556. gs

Bukry, D. (1969). Upper Cretaceous coccoliths from Texas and Europe. University of Kansas Paleontological Contributions, Articles. 51 (Protista 2): 1-79. gs O

Burnett, J. A. (1997c). New species and new combinations of Cretaceous nannofossils and a note on the origin of Petrarhabdus (Deflandre) Wise & Wind. Journal of Nannoplankton Research. 19(2): 133-146. gs

Burnett, J. A. (1998). Upper Cretaceous. In, Bown, P. R. (ed.) Calcareous Nannofossil Biostratigraphy. British Micropalaeontological Society Publication Series . 132-199. gs O

Cepek, P. (1978). Mesozoic calcareous nannoplankton of the Eastern North Atlantic, Leg 41. Initial Reports of the Deep Sea Drilling Project. 41: 667-687. gs

Crux, J. A. (1980). A biostratigraphical study of Upper Cretaceous nannofossils from South-east England and North France. PhD thesis, University College London. -. gs

Lees, J. A. & Bown, P. R. (2005). Upper Cretaceous calcareous nannofossil biostratigraphy, ODP Leg 198 (Shatsky Rise, Northwest Pacific Ocean). Proceedings of the Ocean Drilling Program, Scientific Results. 198: 1-60. gs

Linnert, C. & Mutterlose, J. (2009a). Biometry of the Late Cretaceous Arkhangelskiella group: ecophenotypes controlled by nutrient flux. Cretaceous Research. 30: 1193-1204. gs

Müller, C. (1974). Calcareous nannoplankton, Leg 25 (Western Indian Ocean). Initial Reports of the Deep Sea Drilling Project. 25: 579-633. gs

Perch-Nielsen, K., Sadek, A., Barakat, M. G. & Teleb, F. (1978). Late Cretaceous and Early Tertiary Calcareous nannofossil and Planktonic foraminifera zones from Egypt. Actes du VI Colloque Africain de Micropaléontologie - Tunis 1974. Annales des Mines et de la Géologie Tunissienne. 28: 337-403. gs

Pospichal, J. J. & Wise, S. W. (1990). Maestrichtian calcareous nannofossil biostratigraphy of Maud Rise ODP leg 113 sites 689 and 690, Weddell Sea. Proceedings of the Ocean Drilling Program, Scientific Results. 113: 465-487. gs

Self-Trail, J. M., Parker, M., Govoni, D. L., Bybell, L. M., Gardner, K. F. & Gohn, G. S. (2023). Designation of a composite-stratotype section for the lower Paleocene (Danian) Brightseat Formation in Prince George’s County, Maryland, USA. Stratigraphy. 20(4): 237-258. gs

Sissingh, W. (1977). Biostratigraphy of Cretaceous calcareous nannoplankton. Geologie en Mijnbouw. 65(1): 37-65. gs

Thibault, N. (2010). Calcareous nannofossils from the boreal Upper Campanian- Maastrichtian chalk of Denmark. Journal of Nannoplankton Research. 31(1): 39-56. gs

Varol, O. (1989d). Quantitative analysis of the Arkhangelskiella cymbiformis group and its biostratigraphical usefulness in the North Sea area. Journal of Micropalaeontology. 8: 131-134. gs

Vekshina, V. N. (1959). Coccolithophoridae of the Maastrichtian deposits of the West Siberian lowlands. Trudyi Instituta Geologii i Geogiziki, Sibiriskoe Otlodelenie, Akademiya Nauk SSSR (Nauka) Moscow. 2: 56-81. gs

Arkhangelskiella cymbiformis

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