Dentoglobigerina pseudovenezuelana


Classification: pf_cenozoic -> muricate non-spinose -> Globoquadrinidae -> Dentoglobigerina -> Dentoglobigerina pseudovenezuelana
Sister taxa: D. galavisi, D. juxtabinaiensis, D. prasaepis, D. pseudovenezuelana, D. taci, D. tapuriensis, D. tripartita, D. sp.,

Taxonomy

Citation: Dentoglobigerina pseudovenezuelana (Banner and Blow 1962)
Rank: Species
Basionym: Globigerina yeguaensis pseudovenezuelana
Synonyms:
Taxonomic discussion: Blow (1979) included pseudovenezuelana in his new genus Dentoglobigerina and noted that the increased appression and embrace of the chambers in the ultimate whorl of pseudovenezuelana leads to a test whose equatorial outline becomes less lobulate and more circular. He derived D. pseudovenezuelana from Dentoglobigerina yeguaensis ( =Subbotina yeguaensis) and, in turn, derived yeguaensis from D. galavisi (= Globoquadrina galavisi), based essentially on middle Eocene morphotypes identified by him as galavisi. As noted above in the discussion of G. galavisi, he based his conclusion on a concept of a “central type” for galavisi that differs considerably from the holotype. Having derived yeguaensis from galavisi, it appears that yeguaensis was chosen as the ancestor of pseudovenezuelana. This scenario is rejected because yeguaensis is a spinose subbotinid. It is more likely that D. pseudovenezuelana evolved from D. galavisi, in an evolutionary transition that partially mirrored the earlier origin of Dentoglobigerina tripartita from D. galavisi. [Olsson et al. 2006]

Catalog entries: Globigerina yeguaensis pseudovenezuelana;

Type images:

Short diagnosis: 3-3½ globular slightly compressed chambers in final whorl.
Umbilicus narrow triangular, with irregular pustulose tooth.

NB The short diagnoses are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They have initially been copied from the diagnostic characters/distinguishing features sections of the Eocene and Paleocene Atlases, they will be edited as the site is developed.

Description


Diagnostic characters: The species is characterized by its compact, subcircular to subquadrate test, embracing chambers, and umbilically centered aperture that is bordered by an irregular, subtriangular-shaped lip that projects over the umbilicus, and concentration of pustules in the apertural area. Its test is more compact and the chambers are more flattened than in D. galavisi. Note that the holotype is slightly aberrant in having a final chamber that is about the same size as the penultimate chamber. More regular specimens with proportionally large final chambers are more globular in shape (see Plate 13.2). [Olsson et al. 2006]

Wall type: Cancellate, normal perforate, nonspinose, Globoquadrina-type wall texture. [Olsson et al. 2006]

Test morphology: Test trochospiral, compact, globular, subcircular to subquadrate in outline, chambers ovoid; in spiral view 3½ ovoid chambers in ultimate whorl, increasing moderately in size, sutures moderately depressed, straight; in umbilical view 3 - 3½ ovoid chambers increasing moderately in size, sutures deeply depressed, straight, umbilicus moderate in size, sometimes overlapped by ultimate chamber, aperture centered over the umbilicus, bordered by a thin irregular, subtriangular-shaped lip that projects over the umbilicus, pustules are concentrated in the apertural area; in edge view chambers ovoid in shape, embracing, ultimate chamber extends over the umbilicus, oval to subcircular in outline. [Olsson et al. 2006]

Size: Maximum diameter of holotype 0.51 mm, thickness 0.34 mm. [Olsson et al. 2006]

Character matrix

test outline:Subcircularchamber arrangement:Trochospiraledge view:Equally biconvexaperture:Umbilical
umb chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thin flange
sp chbr shape:Inflatedumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
umbilical or test sutures:Strongly depressedumb depth:Deepwall texture:Cancellateshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Strongly depresseddiameter mm:0.51width mm:breadth mm:0.34
final-whorl chambers:3.0-3.5

Biogeography and Palaeobiology


Geographic distribution: Known only from a few low latitude locations.
[Olsson et al. 2006]
Aze et al. 2011 summary: Low latitudes; based on Olsson et al. (2006b)

Isotope paleobiology: Recorded by Poore and Matthews (1984) and Pearson and others (2001) with relatively positive ∂18O and negative ∂13C indicating a deep planktonic habitat. [Olsson et al. 2006]
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): Wade & Pearson (2008)

Phylogenetic relations: Dentoglobigerina pseudovenezuelana evolved from D. galavisi in the middle/late Eocene by developing more embracing chambers, which led to a compact, subcircular or subquadrate test. [Olsson et al. 2006]

Most likely ancestor: Dentoglobigerina galavisi - at confidence level 4 (out of 5). Data source: Olsson et al 2006, f13.1.

Biostratigraphic distribution

Geological Range:
Notes: Zone E14 to Zone O5? (=P21b). [Olsson et al. 2006]
Last occurrence (top): within O5 zone (26.93-28.09Ma, top in Chattian stage). Data source: Olsson et al 2006
First occurrence (base): within E14 zone (35.89-37.99Ma, base in Bartonian stage). Data source: Olsson et al 2006

Plot of occurrence data:

Primary source for this page: Olsson et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 13, p. 404

References:

Blow, W.H. & Banner, F.T., (1962). The mid-Tertiary (Upper Eocene to Aquitanian) Globigerinaceae. In: Eames, F.E. et al. (Editors), Fundamentals of mid-Tertiary Stratigraphical Correlation. Cambridge University Press, Cambridge, pp. 61-151.

Blow, W.H., (1979). The Cainozoic Globigerinida: A study of the morphology, taxonomy, evolutionary relationships and stratigraphical distribution of some Globigerinida (mainly Globigerinacea). E. J. Brill, Leiden, 1413 pp.

Bolli, H.M. & Saunders, J.B., (1985). Oligocene to Holocene low latitude planktic foraminifera. In: Bolli, H.M., Saunders, J.B. and Perch-Neilsen, K. (Editors), Plankotn Stratigraphy. Cambridge University Press, Cambridge, UK, pp. 155-262.

Olsson, R.K.; Hemleben, C. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Dentoglobigerina. In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Cushman Foundation Special Publication. Allen Press, Lawrence, Kansas, pp. 401-412.

Poore, R.Z. & Matthews, R.K., (1984). Oxygen isotope ranking of late Eocene and Oligocene planktonic foraminifers: implications for Oligocene sea-surface temperatures and global ice-volume. Marine Micropaleontology, 9: 111-134.

Spezzaferri, S. & Premoli Silva, I., (1991). Oligocene planktonic foraminiferal biostratigraphy and paleoclimatic interpretation from Hole 538A, DSDP Leg 77, Gulf of Mexico. Palaeogeography, Palaeoclimatology, Palaeoecology, 83: 217-263.


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Dentoglobigerina pseudovenezuelana compiled by the pforams@mikrotax project team viewed: 24-11-2017

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