pforams@mikrotax - Acarinina cuneicamerata pforams@mikrotax - Acarinina cuneicamerata

Acarinina cuneicamerata


Classification: pf_cenozoic -> Truncorotaloididae -> Acarinina -> Acarinina cuneicamerata
Sister taxa: A. aquiensis ⟩⟨ A. medizzai, A. collactea, A. pentacamerata, A. aspensis, A. interposita, A. echinata, A. pseudosubsphaerica, A. alticonica, A. soldadoensis, A. cuneicamerata, A. angulosa, A. africana, A. sibaiyaensis, A. esnehensis, A. mckannai, A. subsphaerica ⟩⟨ A. bullbrooki, A. punctocarinata, A. boudreauxi, A. rohri, A. topilensis, A. praetopilensis, A. mcgowrani, A. quetra, A. pseudotopilensis> >>

Taxonomy

Citation: Acarinina cuneicamerata (Blow 1979)
Taxonomic rank: species
Basionym: Globorotalia (Acarinina) cuneicamerata
Synonyms:
Taxonomic discussion: This taxon was described by Blow (1979) for predominantly 5-6 chambered (in the final whorl), loosely coiled, muricate forms that exhibit a tendency to develop laterally angulate, disjunct terminal
chambers and a relatively wide open umbilicus. He drew attention to the potential confusion in distinguishing 6-8 chambered forms from the stratigraphically coeval A. aspensis but noted that the smoothly rounded chamber margins (absence of lateral angularity) of aspensis serve to distinguish it from cuneicamerata.
The FAD of A. cuneicamerata has recently been calibrated to Chron C22r at ~50.4 Ma by Hancock and others (2002) at ODP Hole 762C, Exmouth Plateau, north-west Australian margin at essentially the same (estimated) level of the FAD of (the elusive) Planorotalites palmerae which has been used to denote the top of Zone P8 (=Zone E6 of this paper). Accordingly the FAD of this taxon has been used to denote the base of Zone E6 in the recently revised Eocene zonation (Berggren and Pearson, 2005). The little known taxon Globorotalia berwaliana Mohan and Soodan may be a senior synonym. [Berggren et al. 2006]

Catalog entries: Globorotalia (Acarinina) cuneicamerata, Globorotalia berwaliana

Type images:

Distinguishing features:
Parent taxon (Acarinina): Moderate to low trochospire; chambers ovoid, usually 4-6 in final whorl.
Wall muricate with pustules on umbilical shoulders;
This taxon: Chambers subtriangular to wedge-shaped (cuneiform) and lunate, terminal chambers often laterally angulate and peripherally disjunct; umbilicus widely open; densely muricate umbilical side but only weakly muricate spiral side.

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:
This form is distinguished by its combination of subtriangular to wedge-shaped (cuneiform) and lunate chambers, tendency to develop laterally angulate and peripherally disjunct terminal chambers, widely open umbilicus, and densely muricate umbilical side and only weakly muricate spiral side. [Berggren et al. 2006]

Morphology:
Low trochospiral, 5-6 moderately inflated, strongly muricate chambers in last whorl; margins of later chambers in final whorl exhibit tendency to develop angulate and disjunct chamber separation in some individuals; sutures straight, radial, depressed to moderately incised; umbilicus wide, deep, relict apertures of ante- and penultimate chambers visible within umbilical area and bordered by distinct, circumumbilically extending apertural lip(s) connecting to the relatively broad lip of the final chamber; no circumumbilical concentration of muricae; aperture umbilical-extraumbilical, extending towards, but not reaching the periphery; spiral side weakly muricate, about 12, flattened chambers arranged in relatively involute spire of 2 whorls; minute, discrete openings observable, at suture/chamber junctions on well preserved specimens; sutures straight to weakly curved and tangential to periphery; chambers of last whorl lunate with ante- and penultimate chamber often wedge-shaped (cuneiform); in edge view umbilical side is anguloconical with rounded to subacute peripheral margin; spiral side flat. [Berggren et al. 2006]

Wall type:
Densely muricate, non spinose, normal perforate. [Berggren et al. 2006]

Size:
Diameter of holotype 0.41 mm. [Berggren et al. 2006]

Character matrix
test outline:Lobatechamber arrangement:Trochospiraledge view:Planoconvexaperture:Umbilical
sp chamber shape:Inflatedcoiling axis:Lowperiphery:N/Aaperture border:Thick lip
umb chbr shape:Inflatedumbilicus:Wideperiph margin shape:Narrowly roundedaccessory apertures:Relict
spiral sutures:Moderately depressedumb depth:Deepwall texture:Finely muricateshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:4.5-5.5 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution
Equatorial Atlantic Ocean, Tethyan region (Egypt) and Indian Ocean. [Berggren et al. 2006]
Aze et al. 2011 summary: Equatorial Atlantic, Tethyan region and Indian Ocean; based on Berggren et al. (2006b)

Isotope paleobiology
Probably recorded by Boersma and others (1987) (as A. pentacamerata) with negative δ18O indicating a surface water habitat. Pearson and others (2001) recorded it with the most negative δ18O of a large suite of middle Eocene species. [Berggren et al. 2006]
Aze et al. 2011 ecogroup 1 - Open ocean mixed-layer tropical/subtropical, with symbionts. Based on very heavy _13C and relatively light _18O. Sources cited by Aze et al. 2011 (appendix S3): Boersma et al. (1987); Pearson et al. (2001a)

Phylogenetic relations
Probably evolved from Acarinina angulosa and left no descendants. [Berggren et al. 2006]

Most likely ancestor:
Acarinina angulosa - at confidence level 4 (out of 5). Data source: Berggren et al. (2006) fig9.2.

Biostratigraphic distribution

Geological Range:
Notes: Zone E6 (base, by definition) to Zone E9 (lower part) (Blow 1979; Hancock and others, 2002). [Berggren et al. 2006]
The FAD of Acarinina cuneicamerata marks the base of zone E7a / top of E6 (Wade et al. 2011)
Last occurrence (top): in upper part of E8 zone (80% up, 44.2Ma, in Lutetian stage). Data source: Wade et al. 2011, fig 6
First occurrence (base): at base of E7 zone (0% up, 50.2Ma, in Ypresian stage). Data source: zonal marker (Wade et al. 2011)

Plot of occurrence data:

Primary source for this page: Berggren et al. 2006 - Eocene Atlas, chap. 9, p. 280

References:

Berggren, W. A. & Pearson, P. N. (2005). A revised tropical to subtropical Paleogene planktonic foraminiferal zonation. Journal of Foraminiferal Research. -. gs

Berggren, W. A., Pearson, P. N., Huber, B. T. & Wade, B. S. (2006b). Taxonomy, biostratigraphy, and phylogeny of Eocene Acarinina. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 41(Chap 9): 257-326. gs O

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. 2: 1-1413. gs

Hancock, H. J. L., Chaproniere, G. C., Dickens, G. R. & Henderson, R. A. (2002). Early Palaeogene planktic foraminiferal and carbon isotope stratigraphy, Hole 762C, Exmouth Plateau, Northwest Australian margin. Journal of Micropalaeontology. 21: 29-42. gs

Mohan, M. & Soodan, K. S. (1969). Two new Lutetian species of Rotaliina from the Kutch. Journal of the Palaeontological Society of India. 12: 9-11. gs

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

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Acarinina cuneicamerata compiled by the pforams@mikrotax project team viewed: 11-5-2026

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