pforams@mikrotax - Sphaeroidinellopsis paenedehiscens pforams@mikrotax - Sphaeroidinellopsis paenedehiscens

Sphaeroidinellopsis paenedehiscens


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

Taxonomy

Citation: Sphaeroidinellopsis paenedehiscens Blow, 1969
Taxonomic rank: species
Basionym: Sphaeroidinella subdehiscens paenedehiscens Blow, 1969
Synonyms:

Sphaeroidinellopsis sphaeroides Lamb [according to Kennett & Srinivasan 1983]

Catalog entries: Sphaeroidinellopsis subdehiscens paenedehiscens, Sphaeroidinellopsis sphaeroides

Type images:

Distinguishing features:
Parent taxon (Sphaeroidinellopsis): trochospiral test, globular chambers, and a heavy, smooth, shiny cortex
This taxon: Like S. seminulina but more spherical and tightly coiled test and with longer primary aperture. (with supplementary apertures becomes S. dehiscens).

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:
Large, low trochospiral, ovate to smoothly rounded periphery, sutures obscured by thick secondary cortex

Aperture: An elongate umbilical opening following the line of suture of final chamber bordered by crenulated lip which is an extension of secondary cortex [Aze 2011, based on Kennett & Srinivasan 1983]


Morphology:
Test large, low trochospiral, early chambers barely visible, ovate to smoothly rounded in equatorial periphery; chambers 3 in the final whorl, inflated; sutures largely obscured by the secondary test thickening; surface covered by thick, secondary calcareous material (cortex), which restricts the pores and provides a smooth and glossy appearance to the test; aperture an elongate umbilical opening following the line of suture between the last and first chamber of the final whorl, bordered by a crenulated lip, which are extensions of the cortex. [Kennett & Srinivasan 1983]

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

Character matrix
test outline:Ovatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
sp chamber shape:Petaloidcoiling axis:Lowperiphery:N/Aaperture border:N/A
umb chbr shape:Petaloidumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Flushumb depth:Shallowwall texture:Smoothshell porosity:Macroperforate: >2.5µm
umbilical or test sutures:Flushfinal-whorl chambers:3-3 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution
Tropical [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 light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): Pearson & Shackleton (1995)

Phylogenetic relations
Ss. paenedehiscens is distinguished from its ancestor Ss. seminulina seminulina by its more spherical and tightly coiled test and in possessing a longer primary aperture. This species differs from Sphaeroidinella dehiscens by not having supplementary apertures on the spiral side.
The morphological changes that take place in the evolution of Ss. seminulina seminulina to Ss. paenedehiscens include an increase in the size of the test in Ss. paenedehiscens, development of a more spherical test exhibiting less depressed sutures, and conspicuous increase of flange-like apertural lips , which in Ss. seminulina seminulina are restricted to early chambers in the whorl. Unlike Ss. seminulina s.l., populations of Ss. paenedehiscens do not contain any 4-chambered forms in the final whorl. [Kennett & Srinivasan 1983]

Most likely ancestor:
Sphaeroidinellopsis seminulina - at confidence level 3 (out of 5). Data source: Kennett & Srinivasan 1983, fig 23.
Likely descendants: Sphaeroidinella dehiscens; plot with descendants

Biostratigraphic distribution

Geological Range:
Last occurrence (top): within N20 zone (3.10-4.37Ma, top in Piacenzian stage). Data source: Kennett & Srinivasan 1983
First occurrence (base): within N17b zone (5.72-6.60Ma, base in Messinian stage). Data source: Kennett & Srinivasan 1983

Plot of occurrence data:

Primary source for this page: Kennett & Srinivasan 1983, p.210

References:

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

Blow, W. H. (1969). Late middle Eocene to Recent planktonic foraminiferal biostratigraphy. In, Bronnimann, P. & Renz, H. H. (eds) Proceedings of the First International Conference on Planktonic Microfossils, Geneva, 1967. E J Brill, Leiden 380-381. gs

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

Lam, A. & Leckie, R. M. (2020a). Late Neogene and Quaternary diversity and taxonomy of subtropical to temperate planktic foraminifera across the Kuroshio Current Extension, northwest Pacific Ocean. Micropaleontology. 66(3): 177-268. gs

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

Pearson, P. N. & Shackleton, N. J. (1995). Neogene multispecies planktonic foraminifer stable isotope record, Site 871, Limalok Guyot. Proceedings of the Ocean Drilling Program, Scientific Results. 144: 401-410. gs

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Sphaeroidinellopsis paenedehiscens compiled by the pforams@mikrotax project team viewed: 12-6-2026

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