Sphaeroidinellopsis disjuncta


Classification: pf_cenozoic -> Globigerinidae -> Sphaeroidinellopsis -> Sphaeroidinellopsis disjuncta
Sister taxa: S. paenedehiscens, S. kochi, S. seminulina, S. disjuncta, S. sp.,

Taxonomy

Citation: Sphaeroidinellopsis disjuncta (Finlay, 1940)
Rank: species
Basionym: Sphaeroidinella disjuncta Finlay, 1940

Catalog entries: Sphaeroidinella disjuncta

Type images:

Distinguishing features: Intermediate between G. woodi and S. seminulina, test thickened but without cortex.

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: Low trochospiral, equatorial periphery trilobate to quadrilobate, chambers spherical to ovate

Aperture: Interiomarginal umbilical bordered by thickened rim [Aze 2011, based on Kennett & Srinivasan 1983]


Wall type: Non-spinose; Cancellate [Aze 2011]

Test morphology: Test low trochospiral, equatorial periphery trilobulate to quadrilobulate; chambers spherical to ovate, 4 in the final whorl; sutures on both spiral and umbilical sides distinct, radial, depressed; surface thick, cancellate, interpore areas thickened but not glossy; umbilicus small, deep; aperture interio-marginal, umbilical, bordered by a thick rim. [Kennett & Srinivasan 1983]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
sp chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:Thick lip
umb chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:Deepwall texture:Cancellateshell porosity:Macroperforate: >2.5µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:4.0-4.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: Temperate to warm subtropical. [Kennett & Srinivasan 1983] Low latitudes [Aze et al. 2011, based on Kennett & Srinivasan (1983)]

[SCOR WG138]


Isotope paleobiology: Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on comparison with other species of the genus

Phylogenetic relations: Ss. disjuncta differs morphologically from Globigerina (Zeaglobigerina) woodi in exhibiting a much more thickened test, although the surface character in Ss. disjuncta still lacks the highly thickened glossy appearance typical of Sphaeroidinellopsis. Specimens of Ss. disjuncta exhibiting three chambers in the final whorl closely resemble Globigerina (Zeaglobigerina) connecta Jenkins. The surface ultrastructure in Ss. disjuncta is intermediate in character between the distinct reticulate pattern of Gg. (Zg.) woodi and the smooth, glossy cortex of Sphaeroidinellopsis. Because the test wall in Ss. disjuncta shows such a strong tendency to thicken, we prefer to assign this form to Sphaeroidinellopsis rather than Globigerina (Zeaglobigerina). Ujiie (1976) has referred the early, less-thickened forms of Sphaeroidinellopsis to Prosphaeroidinella. We do not use this taxa because within a phylogenetic framework, it is not necessary to refer to the intermediate forms between Globigerina and Sphaeroidinellopsis as a separate genus.
Banner and Blow (1959) considered Ss. disjuncta to be a synonym of Ss. seminulina, but we disagree for the reasons outlined by Jenkins (1971). Ss. disjuncta evolved from Gg. (Zg.) woodi and is ancestral to Ss. seminulina (Schwager). [Kennett & Srinivasan 1983]

Most likely ancestor: Globoturborotalita woodi - at confidence level 3 (out of 5). Data source: Kennett & Srinivasan 1983.
Likely descendants: Sphaeroidinellopsis seminulina;

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within N11 zone (13.41-13.77Ma, top in Serravallian stage). Data source: Kennett & Srinivasan 1983
First occurrence (base): within N6 zone (17.54-17.59Ma, base in Burdigalian stage). Data source: Kennett & Srinivasan 1983

Plot of occurrence data:

Primary source for this page: Kennett & Srinivasan 1983, p.206

References:

Aze, T. et al. (2011). A phylogeny of Cenozoic macroperforate planktonic foraminifera from fossil data. Biological Reviews. 86: 900-927. gs

Banner, F. T. & Blow, W. H. (1959). The classification and stratigraphical distribution of the Globigerinaceae. Palaeontology. 2(1): 1-27. gs

Finlay, H. J. (1940). New Zealand foraminifera: Key species in stratigraphy - no. 4. Transactions of the Royal Society of New Zealand. 69(4): 448-472. gs

Fox, L. R. & Wade, B. S. (2013). Systematic taxonomy of early–middle Miocene planktonic foraminifera from the equatorial Pacific Ocean: Integrated Ocean Drilling Program, Site U1338. Journal of Foraminiferal Research. 43: 374-405. gs

Jenkins, D. G. (1971). New Zealand Cenozoic Planktonic Foraminifera. New Zealand Geological Survey, Paleontological Bulletin. 42: 1-278. gs

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

Norris, R. D. (1998). Planktonic foraminifer biostratigraphy: Eastern Equatorial Atlantic. Proceedings of the Ocean Drilling Program, Scientific Results. 159: 445-479. gs

Ujiie, H. (1976). Prosphaeroidinella, n. gen.: Probable ancestral taxon of Sphaeroidinellopsis (Foraminifera),. Bulletin of the National Science Museum, Series C. 2(1): 9-26. gs


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Sphaeroidinellopsis disjuncta compiled by the pforams@mikrotax project team viewed: 16-12-2019

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