Globanomalina ovalis


Classification: pf_cenozoic -> smooth non-spinose -> Hedbergellidae -> Globanomalina -> Globanomalina ovalis
Sister taxa: G. archeocompressa, G. australiformis, G. chapmani, G. compressa, G. ehrenbergi, G. imitata, G. luxorensis, G. ovalis, G. planocompressa, G. planoconica, G. pseudomenardii, G. sp.,

Taxonomy

Citation: Globanomalina ovalis Haque 1956
Rank: Species
Basionym: Globanomalina
Synonyms:
Taxonomic discussion:

Banner's (1989) study clarified the taxonomic position of the genus Globanomalina and the type species ovalis. Banner correctly pointed out that as the number of chambers increase from 5 to 6 in the ultimate whorl the test becomes asymmetrically planispirally arranged. In addition, the aperture, which is a fairly high arch, bordered by a continuous, thin lip, migrates slightly onto the spiral side. The test walls are perforate throughout, and, although Banner described the wall as microperforate, we include G. ovalis in the normal perforate category, which contrasts with microperforate taxa (test walls with pore diameters 0.3-0.45 µm in diameter) of the Guembelitridae. As Banner (1989) pointed out in his study, Globigerina pseudoiota Homibrook (1958) should be regarded as a junior synonym of G. ovalis. The form illustrated by Blow (1979, pl.111 : fig. 5) as an intermediate between G. chapmani (Parr) and Pseudohastigerina wilcoxensis (Cushman and Ponton) is a smooth-walled, 6-chambered, nearly planispiral form that has an extraumbilical aperture extending slightly onto the dorsal side. We agree with Blow that this morphology is transitional to Pseudohastigerina, but that it is represented in the species G. ovalis. [Olsson et al. 1999]

Catalog entries: Globanomalina ovalis;
Globigerina pseudoiota;

Type images:

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:

 


Emended description: Emended description: "Globanomalina as here defined, with six chambers per whorl initially, sometimes retaining this number in the last-formed whorl but sometimes reducing it to five; the rate of chamber volume increase with chamber addition is approximately the same in each form, so that (a) when the chamber number is reduced (e.g., to five in the last whorl) the spiral side of the test remains completely evolute and flat or slightly convex in shape, or (b) when the final chamber number is not reduced (e.g., is retained at about six in the last whorl) the final chambers overlap slightly onto the spiral side, so that that side becomes incompletely evolute and slightly concave in shape; wall is microperforate, with perforation canaliculi about 1 µm in diameter, opening into broadly and bluntly rounded perforation pits about 10 µm in diameter (the perforation pits are deeper on the earlier chambers which have had their walls thickened by test growth); maximum diameter achieved is about 0.34 mm." (Banner, 1989:177.) [Olsson et al. 1999]

Character matrix

test outline:Ellipticalchamber arrangement:Trochospiraledge view:Equally biconvexaperture:-
umb chamber shape:Inflatedcoiling axis:Very lowperiphery:N/Aaperture border:Thin lip
sp chbr shape:Inflatedumbilicus:Wideperiph margin shape:Broadly roundedaccessory apertures:None
umbilical or test sutures:Moderately depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Moderately depresseddiameter mm:0.26width mm:0.14breadth mm:0.21
final-whorl chambers:6.0-6.0

Biogeography and Palaeobiology


Geographic distribution: Northern and southern mid-latitudes [Olsson et al. 1999]
Aze et al. 2011 summary: Northern and southern middle latitudes; based on Olsson et al. (1999)

Isotope paleobiology: No data available
Aze et al. 2011 ecogroup 2 - Open ocean mixed-layer tropical/subtropical, without symbionts. Based on δ13C lighter than species with symbionts; also with relatively light δ18O. Sources cited by Aze et al. 2011 (appendix S3): this study

Phylogenetic relations:

This species is a member of the inflated chamber, perforate walled lineage in Globanomalina. Globanomalina ovalis evolved from G. imitata in the upper part of Zone P4 by an increase in the number of chambers in the ultimate whorl from 5 to 6, a greater degree of inflation of the chambers, and the trend towards planispirality (see Plate 36: Figures 13-15). Although Berggren et al., 1967, and Banner, 1989, stated that G. ovalis derived from G. chapmani, there is a distinct difference in the wall texture between the two species that would appear to preclude a phylogenetic linkage. In the Pondicherry section of southeast India G. ovalis and G. imitata overlap morphologically. [Olsson et al. 1999]

Biostratigraphic distribution

Geological Range:
Notes: Zone P4c to Zone E1. [Olsson & Hemleben 2006]
Last occurrence (top): within E6 zone (50.20-50.67Ma, top in Ypresian stage). Data source: Eocene Atlas
First occurrence (base): within P4c subzone (57.10-57.79Ma, base in Thanetian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 43

References:

Haque, A.F.M.M., (1956). The smaller foraminifera of the Ranikot and the Laki of the Nammal gorge, Salt Range. Memoir of the Pakistan Geological Survey, 1: 1-300.

Olsson, R.K. & Hemleben, C., (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene Globanomalina, Planoglobanomalina n. gen and Pseudohastigerina. 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. 413-432.

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Huber, B.T., (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Contributions to Paleobiology. Smithsonian Institution Press, Washington, DC, 1-252 pp.


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Globanomalina ovalis compiled by the pforams@mikrotax project team viewed: 24-9-2017

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