pforams@mikrotax - Fohsella

Basionym: Globorotalia (Fohsella) Bandy 1972

Type species: Globorotalia (Globorotalia) praefohsi Blow and Banner, 1966

Synonyms:

Globorotalia (Fohsella) Bandy 1975
Fohsella Bandy 1975
fohsi lineage - this label was previously on used on pforams@mikrotax.

Taxonomic discussion: The subgenus Fohsella was proposed by Bandy (1972) for the well-known G. peripheroronda to Gr. fohsi robusta bioseries. In his diagnosis, Bandy (1972) restricted the name Fohsella for sharp- to keel-edged members only. We agree with Fleisher (1974) in considering this definition to be too restrictive and that forms should also be included with a rounded periphery such as Gr. peripheroronda, Gr. birnageae, and Gr. kugleri because they represent early members of the Fohsella lineage (Text Fig. 12).
The subgenus Fohsella is an important lineage in the tropics and forms the basis for the early Middle Miocene planktonic foraminiferal zonation (Bolli, 1957a, Blow, 1969). The evolutionary development of this bioseries has been well documented by a number of authors (Bolli, 1957a, 1967; Blow and Banner, 1966; Olsson, 1971, 1972; Srinivasan and Kennett, 1981a).
Important changes within the Fohsella lineage are a size increase of specimens and the development of a nonkeeled to a keeled periphery. A sudden and rapid increase in average test size in later members of the Fohsella lineage was interpreted by Olsson (1972) to be in response to the climax of global climatic warming during the Middle Miocene. All of the species included in the subgenus Fohsella are marked by a smooth, secondary calcite crust, which covers and sometimes obscures the pores in the early chambers (PI.21,Figs.1,2).The early members of this lineage- Gr. (F.) kugleri, Gr. (F.) peripheroronda, and Gr. (F.) birnageae-morphologically resemble forms included in the new subgenus Jenkinsella [=Paragloborotalia] but are phylogenetically unrelated. The ancestry of the subgenus Fohsella is uncertain. [Kennett & Srinivasan 1983].

Following discussion among members of the Neogene planktonic foraminiferal working group, we are now using the name Fohsella on mikrotax. This reflects the observations that (1) The genus was validly proposed by Bandy (1972); (2) The genus has a separate evolutionary origin, within Paragloborotalia, from the main Globorotalia lineage; (3) This usage has been followed by many workers. [editor's comment - JRY, May 2019].

Distinguishing features:
Parent taxon (Globorotaliidae): Macroperforate, non-spinose
This taxon: G. peripheroronda - lenguaensis - fohsi - robusta lineage

Description

Biogeography and Palaeobiology

Both Aze et al. (2011) and Leckie et al. (2018) record the fohsi lineage as originating from Paragloborotalia. Since it is imterpreted as having a separate origin from the other Globorotalia lineages the name Fohsella should be used. [editor's comment - JRY 2018]

Within the main fohsi lineage there is a shift from random coiling to predominantly sinistral coiling within zone N12 (=M9) this was outlined by Bolli & Saunders (1985) and documented in more detail by Winter & Pearson (2001).

Most likely ancestor: Paragloborotalia - at confidence level 3 (out of 5). Data source: Leckie et al. (2018).

Biostratigraphic distribution

Geological Range:
Last occurrence (top): at top of M13 zone (100% up, 6.1Ma, in Messinian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within N4b zone (22.20-23.50Ma, base in Chattian stage). Data source: Total of ranges of species in this database

References:

Bandy, O. L. (1972). Origin and development of Globorotalia (Turborotalia) pachyderma (Ehrenberg). Micropaleontology. 18(3): 294-318. gs

Bolli, H. M. & Saunders, J. B. (1985). Oligocene to Holocene low latitude planktic foraminifera. In, Bolli, H. M., Saunders, J. B. & Perch-Neilsen, K. (eds) Plankton Stratigraphy. Cambridge University Press, Cambridge, UK 155-262. gs

Fleisher, R. L. (1974a). Cenozoic planktonic foraminifera and biostratigraphy, Arabian Sea, Deep Sea Drilling Project, Leg 23A. Initial Reports of the Deep Sea Drilling Project. 23: 1001-1072. gs O

Kennett, J. P. & Srinivasan, M. S. (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania. 1-265. gs

Winter, C. J. & Pearson, P. N. (2001). Coiling directions in some Miocene planktonic Foraminifera. Journal of Micropalaeontology. 20(1): 29-30. gs

Species in lineage order, oldest at base (time control age-window is: 0-800Ma)
			Late Miocene species
			Fohsella paralenguaensis Like F. lenguaensis but less circular and test less tightly coiled
			Fohsella lenguaensis Small with circular equatorial profile, and smooth, densely perforate, test
			main lineage
			Fohsella robusta Like F. lobata but nearly circular outline and more convex umbilical side.
			Fohsella lobata Like F. fohsi but larger and with characteristic cockscomb-shaped peripheral margin
			Fohsella fohsi Like F. praefohsi, but with a distinct keel throughout the entire final whorl.
			Fohsella praefohsi Like F. peripheroacuta but with a keel (imperforate carina) on the final 1 or 2 chambers
			Fohsella peripheroacuta Like F. peripheroronda but acutely compressed periphery in the later chambers of the final whorl.
			Fohsella peripheroronda Umbilico-convex, very low trochospiral, equatorial periphery slightly lobulate

Fohsella

Taxonomy

Description

Biogeography and Palaeobiology

Biostratigraphic distribution

References:

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