Taxonomic discussion: Schwager (1866) originally described Ss. seminulina from the Early Pliocene of Car Nicobar Island (Srinivasan and Sharma, 1974). Since the holotype and primary paratypes for Ss. seminulina (Schwager) had been lost, it was necessary to designate neotypes,which Banner and Blow (1960) described after examination of metatype material curated at the British Museum of Natural History. These metatypes are dominated by 3-chambered forms (fourteen of eighteen specimens) similar to one figured by Schwager (1866). Yet Banner and Blow (1960) selected one of the atypical 4-chambered specimens as the neotype. This has since given the impression that Ss. seminulina is dominantly a 4-chambered form (Stainforth et al. 1975). At about the same time, Blow (1959) erected a new species, Ss. subdehiscens, which he considered to be different from Ss. seminulina by having three chambers in the final whorl. Comparison of topotypes of Ss. seminulina from Car Nicobar Island (PI. 51, Figs. 1,6, 7) with forms described by Blow as Ss. subdehiscens shows no significant differences in chamber number, in the structure of the cortex, or in the apertural characters. Therefore Srinivasan and Kennett (1981b) considered Ss. subdehiscens to be a synonym of Ss. seminulina and consequently redesignated Ss. seminulina (Schwager) to be the genotype of Sphaeroidinellopsis. [Kennett & Srinivasan 1983]
Distinguishing features: Parent taxon (Sphaeroidinellopsis): trochospiral test, globular chambers, and a heavy, smooth, shiny cortex This taxon: Compact, low trochospiral, subglobular, sutures obscured by secondary cortex Aperture: Umbilical, elongate opening with thickened, crenulated, rim
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.
Aperture: Umbilical elongate opening bordered by thickened crenulated rim [Aze 2011, based on Kennett & Srinivasan 1983]
Morphology: Test low trochospiral, compact, equatorial periphery broadly ovate to slightly trilobulate; 3 subglobular chambers in the final whorl; sutures obscured by heavy cortex; surface coarsely perforate, covered by secondary layer of shell material (cortex) reducing the pore openings and providing a smooth, polished, and glossy appearance to the test (PI. 51, Fig. 1). Umbilicus open; aperture an elongate umbilical opening bordered by thickened crenulate margin. [Kennett & Srinivasan 1983] Wall type:
K_S 1983 51-1.JPG
Non-spinose; Cancellate with smooth cortex [Aze 2011]
Character matrix
test outline:
Subtriangular
chamber arrangement:
Trochospiral
edge view:
Equally biconvex
aperture:
Umbilical
sp chamber shape:
Petaloid
coiling axis:
Low
periphery:
N/A
aperture border:
Thick lip
umb chbr shape:
Petaloid
umbilicus:
Narrow
periph margin shape:
Broadly rounded
accessory apertures:
None
spiral sutures:
Flush
umb depth:
Shallow
wall texture:
Smooth
shell porosity:
Macroperforate: >2.5µm
umbilical or test sutures:
Flush
final-whorl chambers:
3-3
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionTropical to warm subtropical. [Kennett & Srinivasan 1983]
Low latitudes [Aze et al. 2011, based on Kennett & Srinivasan (1983)]
[SCOR WG138]
Isotope paleobiologyAze 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): D. R. M. Stewart unpublished data Phylogenetic relationsOur concept of evolution within Sphaeroidinellopsis through much of the Middle and Late Miocene differs markedly from that described by Blow (1969). We have not detected any significant evolution during the Middle to Late Miocene, while Blow postulated an evolutionary gradation from Ss. seminulina to Ss. subdehiscens at the base of Zone N13 (Middle Miocene). Further evolution within the Sphaeroidinellopsis lineage does occur within the Late Miocene Zone N17B as observed in tropical Site 289. This involves the evolutionary transition from Ss. seminulina to Ss. paenedehiscens Blow. [Kennett & Srinivasan 1983]
Geological Range: Last occurrence (top): at top of PL3 [Atl.] zone (100% up, 3.2Ma, in Piacenzian stage). Data source: Wade et al. (2011), zonal marker - but occurs earlier in the Pacific First occurrence (base): within N7 zone (16.38-17.54Ma, base in Burdigalian stage). Data source: Kennett & Srinivasan 1983 - this is range including triloba as a synonym
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested.
Grey shading between taxa indicates intergrading species within an anagenetic lineage (data from
Lamyman et al. 2026).
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
Primary source for this page: Kennett & Srinivasan 1983, p.206
References:
Banner, F. T. & Blow, W. H. (1960a). Some primary types of species belonging to the superfamily Globigerinaceae. Contributions from the Cushman Foundation for Foraminiferal Research. 11: 1-41. gsO
Blow, W. H. (1959). Age, correlation, and biostratigraphy of the upper Tocuyo (San Lorenzo) and Pozon Formations, eastern Falcon, Venezuela. Bulletins of American Paleontology. 39(178): 67-251. 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
Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs
Schwager, C. (1866). Fossile Foraminiferen von Kar Nikobar, Reise der Oesterreichischen Fregatte Novara um Erde in den Jahren 1857, 1858, 1859 unten den Befehlen des Commodore B. Von Wuellerstorf-Urbair. Geologischer Theil, Geologische Beobachtung no. 2, Palaeontologische Mittheilung. 2: 187-268. gsO
Stainforth, R. M., Lamb, J. L., Luterbacher, H., Beard, J. H. & Jeffords, R. M. (1975). Cenozoic planktonic foraminiferal zonation and characteristics of index forms. University of Kansas Paleontological Contributions, Articles. 62: 1-425. gsO
Stewart, D. R. M. I. (2003). Evolution of Neogene globorotaliid foraminifera and Miocene climate change. PhD thesis, Bristol University. 1-269. gsO
Wade, B. S., Pearson, P. N., Berggren, W. A. & Pälike, H. (2011). Review and revision of Cenozoic tropical planktonic foraminiferal biostratigraphy and calibration to the geomagnetic polarity and astronomical time scale. Earth-Science Reviews. 104: 111-142. gs
Sphaeroidinellopsis seminulina compiled by the pforams@mikrotax project teamviewed: 18-7-2026
K_S 1983 51-6.JPG
Postuma 1971 p389-4.JPG
Postuma 1971 p275-7.JPG
Postuma 1971 p389-7.JPG
K_S 1983 51-6.JPG
Postuma 1971 p389-4.JPG
Postuma 1971 p275-7.JPG
Postuma 1971 p389-7.JPG
holotype: G. seminulina
neotype: G. seminulina_P44035_Neo.JPG)
neotype: G. seminulina
K_S 1983 51-1.JPG
