pforams@mikrotax - Subbotina jacksonensis pforams@mikrotax - Subbotina jacksonensis

Subbotina jacksonensis


Classification: pf_cenozoic -> Globigerinidae -> Subbotina -> Subbotina jacksonensis
Sister taxa: S. projecta, S. tecta, S. jacksonensis, S. corpulenta, S. eocaena, S. gortanii, S. crociapertura, S. yeguaensis, S. senni, S. roesnaesensis ⟩⟨ S. utilisindex, S. angiporoides, S. minima, S. linaperta, S. patagonica ⟩⟨ S. cancellata, S. hornibrooki, S. velascoensis, S. triloculinoides, S. triangularis, S. trivialis, S. sp.

Taxonomy

Citation: Subbotina jacksonensis (Bandy 1949)
Taxonomic rank: species
Basionym: Globigerina rotundata jacksonensis
Synonyms:
Taxonomic discussion: We illustrate in SEM for the first time the holotype of Subbotina jacksonensis (Pl.6.13, Figs. 1-3). This species has been apparently overlooked by workers, or grouped with other subbotinid species, or placed in Catapsydrax. The ultimate chamber, even though it projects over and covers the umbilicus, cannot be regarded as a bulla. It represents the terminal stage in the ontogeny of the individual and shows varying degrees of wall texture development among individuals of the species, a common feature in planktonic foraminifera. The species is fairly common in our upper Eocene samples. Globigerina ouachitaensis senilis Bandy was described from a sample in the Yazoo Clay close to the sample from which S. jacksonensis was described. Globigerina senilis was described as having a small ultimate chamber that restricts the opening to the umbilicus, which is observed within the normal range of morphologic variation in S. jacksonensis.
SEM images of Globigerina (Eoglobigerina) bizkaiensis Orue -Etxebarria from the middle Eocene of Spain are identical with holotype and other images of S. jacksonensis. [Olsson et al. 2006]

Catalog entries: Globigerina rotundata jacksonensis, Globigerina (Eoglobigerina) bizkaiensis

Type images:

Distinguishing features:
Parent taxon (Subbotina): Low trochospiral, tripartite test, with 3-4 rapidly inflating, globular chambers in final whorl. Umbilicus nearly closed by tight coiling. Wall cancellate with spines at nodes of the ridges, +/- spine collars.
This taxon: Test globular, chambers much embracing. Final chamber reduced, projecting over and covering the umbilicus.

NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus.
They are being edited as the site is developed and comments on them are especially welcome.

Description


Diagnostic characters:

The species is characterized by its globular test, much embracing chambers, with a reduced ultimate chamber projecting over and covering the umbilicus. [Olsson et al. 2006]

Character matrix
test outline:Lobatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
sp chamber shape:Globularcoiling axis:Low-moderateperiphery:N/Aaperture border:N/A
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:Deepwall texture:Spinoseshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:3-4 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution

Global in low-to mid-latitudes. [Olsson et al. 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Olsson et al. (2006a)

Isotope paleobiology
No data available. [Olsson et al. 2006]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light _13C and relatively heavy _18O. Sources cited by Aze et al. 2011 (appendix S3): Coxall et al. (2000)

Phylogenetic relations
Subbotina jacksonensis probably evolved from Subbotina eocaena by developing more embracing chambers and a reduced ultimate chamber that projects over the umbilicus. [Olsson et al. 2006]

Most likely ancestor: Subbotina eocaena - at confidence level 4 (out of 5). Data source: Olsson et al. 2006 f6.2.

Biostratigraphic distribution

Geological Range:
Notes: Zone E9 (upper part) to Zone E16. [Olsson et al. 2006]
Last occurrence (top): within E16 zone (33.90-34.68Ma, top in Priabonian stage). Data source: Eocene Atlas
First occurrence (base): within E9 zone (43.23-43.85Ma, base in Lutetian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Olsson et al. 2006 - Eocene Atlas, chap. 6, p. 146

References:

Bandy, O. L. (1949). Eocene and Oligocene foraminifera from Little Stave Creek, Clarke County, Alabama. Bulletins of American Paleontology. 32(131): 1-210. gs

Blow, W. H. & Banner, F. T. (1962). The mid-Tertiary (Upper Eocene to Aquitanian) Globigerinaceae. In, Eames, F. E., Banner, F. T., Blow, W. H. & Clarke, W. J. (eds) Fundamentals of mid-Tertiary Stratigraphical Correlation. Cambridge University Press, Cambridge 61-151. gs

Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (2006a). Taxonomy, biostratigraphy, and phylogeny of Eocene Globigerina, Globoturborotalita, Subbotina, and Turborotalita. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 41(Chap 6): 111-168. gs O

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Subbotina jacksonensis compiled by the pforams@mikrotax project team viewed: 29-4-2025

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