Turborotalia pomeroli

Classification: pf_cenozoic -> smooth non-spinose -> Hedbergellidae -> Turborotalia -> Turborotalia pomeroli
Sister taxa: T. altispiroides, T. ampliapertura, T. cerroazulensis, T. cocoaensis, T. cunialensis, T. frontosa, T. increbescens, T. pomeroli, T. possagnoensis, T. sp.,


Citation: Turborotalia pomeroli (Toumarkine & Bolli 1970)
Rank: Species
Basionym: Globorotalia pomeroli
Taxonomic discussion: This species was described by Toumarkine and Bolli (1970) as an evolutionary intermediate in a lineage between T. possagnoensis and T. cerroazuelensis, but multivariate morphometric studies (P. N. Pearson, unpublished data) suggest a more complicated situation. Populations of T. pomeroli are highly variable in morphology and were apparently at the root of a substantial radiation in the middle Eocene. T. pomeroli intergrades with T. frontosa near the level of its first appearance (Zones E9-E10), and at higher levels with T. altispiroides, T. cerroazulensis, T. increbescens and T. ampliapertura. Blow (1979) considered it as a junior synonym of Globorotalia centralis Cushman and Bermúdez, and indeed the concept of centralis articulated by Blow and Banner (1962) and Blow (1969, 1979) accords closely with pomeroli. In our view, however, centralis is a synonym of cerroazulensis (see above).
Globigerina subcorpulenta Khalilov, which was regarded by Blow (1979) as a junior synonym of Globorotalia centralis Cushman and Bermúdez, has been viewed by W. A. Berggren (pers. comm.) as part of this study. Although poorly preserved, it is a potential senior synonym of pomeroli. Similarly, Globorotalia inflata Hussey is a poorly understood species that was dismissed by Blow (1979) as a secondary subjective homonym of Globigerina inflata (d’Orbigny) (both of which he placed in Globorotalia). This would not be the case if Hussey’s taxon was found to be a Turborotalia, as seems likely from examination under light microscope (P. N. Pearson, observed 1997), in which case it might also be regarded as another senior synonym of pomeroli. Globorotalia pseudomayeri Bolli, 1957c is another species that may be a prior synonym. Blow (1979) recognized its turborotalid affinities. A questionable further prior synonym that we have not studied is Globorotalia kiewensis Morozova. However, as all four taxa have rarely been noticed, we recommend retaining pomeroli for stability of nomenclature. [Pearson et al. 2006]

Catalog entries: Globigerina subcorpulenta;
Globorotalia inflata;
Globorotalia pomeroli;
Globorotalia pseudomayeri;

Type images:

Short diagnosis: Turborotalia pomeroli is distinguished from T. frontosa and T. possagnoensis by its more compressed chamber morphology, generally larger size and in having at least four chambers in the final whorl.

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.


Diagnostic characters: Turborotalia pomeroli is distinguished from T. frontosa and T. possagnoensis by its more compressed chamber morphology, generally larger size and in having at least four chambers in the final whorl. [Pearson et al. 2006]

Wall type: Smooth, normal perforate with cylindrical pustules around umbilicus, weakly cancellate on earlier chambers; tendency to defoliate. [Pearson et al. 2006]

Test morphology: Large, high to moderate trochospiral, globular with 4 (rarely 5) chambers in the final whorl; chambers inflated, strongly radially compressed and appressed, increasing moderately in size, with final chamber commonly flattened in a radial direction and added high in the spiral, arching towards the umbilicus; dorsal sutures slightly curved, depressed; aperture a broad, often irregular arch in umbilical-extraumbilical position, sometimes extending almost to the periphery; occasionally an imperforate lip visible, but more commonly obscured by inward folding of the final chamber; umbilicus generally narrow; ventral sutures slightly curved, depressed; usually a weak tendency for either dextral or sinistral coiling. [Pearson et al. 2006]

Size: Holotype length 0.51 mm, breadth 0.44 mm, height 0.34 mm. [Pearson et al. 2006]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Inequally biconvexaperture:Umb.-extraumbilical
umb chamber shape:Globularcoiling axis:Moderate-highperiphery:N/Aaperture border:Thin lip
sp chbr shape:Globularumbilicus:Narrowperiph margin shape:Broadly roundedaccessory apertures:None
umbilical or test sutures:Moderately depressedumb depth:Deepwall texture:Smoothshell porosity:Finely Perforate: 1-2.5
spiral sutures:Moderately depresseddiameter mm:0.51width mm:0.44breadth mm:0.34
final-whorl chambers:4.0-5.0

Biogeography and Palaeobiology

Geographic distribution: Cosmopolitan; probably the most abundant and widely distributed of all Turborotalia, being very well represented in both tropical and temperate regions. [Pearson et al. 2006]
Aze et al. 2011 summary: Cosmopolitan; based on Pearson et al. (2006)

Isotope paleobiology: Recorded as having relatively negative ∂18O by Boersma and others (1987) (as T. centralis). Similar data were presented by Pearson and others (2001), indicating a shallower habitat than co-occurring T. cerroazulensis. [Pearson et al. 2006]
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): Boersma et al. (1987); Pearson et al. (2001a)

Phylogenetic relations: Evolved from Turborotalia frontosa in the middle Eocene and was ancestral to T. cerroazulensis, T. altispiroides and T. increbescens. [Pearson et al. 2006]

Biostratigraphic distribution

Geological Range:
Notes: Middle Eocene, upper Zone E11 to within Zone E15 (Toumarkine and Bolli, 1970). [Pearson et al. 2006]
Last occurrence (top): within E15 zone (34.68-35.89Ma, top in Priabonian stage). Data source: Eocene Atlas
First occurrence (base): within E11 zone (40.40-41.89Ma, base in Lutetian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Pearson et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 15, p. 454


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Turborotalia pomeroli compiled by the pforams@mikrotax project team viewed: 19-8-2017

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