pforams@mikrotax - Clavigerinella akersi pforams@mikrotax - Clavigerinella akersi

Clavigerinella akersi


Classification: pf_cenozoic -> Hantkeninidae -> Clavigerinella -> Clavigerinella akersi
Sister taxa: C. akersi, C. caucasica, C. colombiana, C. eocanica, C. jarvisi, C. sp.

Taxonomy

Citation: Clavigerinella akersi Bolli, Loeblich & Tappan 1957
taxonomic rank: Species
Basionym: Clavigerinella akersi
Synonyms:
Taxonomic discussion: Complete specimens are rare. It is usually recognized from detached chambers. [Coxall & Pearson 2006]

Catalog entries: Clavigerinella akersi

Type images:

Distinguishing features:
Parent taxon (Clavigerinella): Final chambers clavate.
This taxon: Final chambers with bulbous terminal swellings

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


Morphology:
Planispiral or pseudoplanispiral, evolute, biumbilicate or showing a subtly raised spiral side and very shallow umbilicus; 4-4½ rapidly enlarging chambers in the final whorl; final 2-4 chambers radially elongate to digitate, giving the shell a highly lobulate peripheral outline; distal chamber ends of some or all of the chambers terminate in distinctly spherical, bulbous swellings; equatorial high arched aperture, symmetrical or slightly asymmetrical, bordered by a smooth broad, imperforate lip; relict apertural lips commonly form web-like extension along sutures; sutures are shallow, straight, becoming curved, short compared to overall chamber height. [Coxall & Pearson 2006]

Wall type:
Smooth, normal perforate or weakly cancellate, possibly spinose. [Coxall & Pearson 2006]

Size:
Maximum diameter of holotype 0.86 mm, greatest thickness 0.23 mm. Paratypes range from 0.49 to 0.73 mm in greatest diameter (Bolli, Loeblich and Tappan, 1957). [Coxall & Pearson 2006]

Character matrix
test outline:Stellatechamber arrangement:Planispiraledge view:Compressedaperture:Umbilical
sp chamber shape:Elongatecoiling axis:N/Aperiphery:N/Aaperture border:Thick lip
umb chbr shape:Elongateumbilicus:Wideperiph margin shape:Moderately roundedaccessory apertures:Relict
spiral sutures:Weakly depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Weakly depressedfinal-whorl chambers:2-4 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution

Worldwide at low to mid latitudes. Rare in open-ocean oligotrophic assemblages, occasionally common in paleoupwelling/ high productivity environments.
[Coxall & Pearson 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Coxall & Pearson (2006)

Isotope paleobiology
Clavigerinella akersi registers very high δ18O and low δ13C compared to other co-existing planktonic species indicating that it lived in cold, 12C-rich water masses indicative of a deep subthermocline habitat or upwelling (Coxall, 2000). [Coxall & Pearson 2006]
Aze et al. 2011 ecogroup 4 - Open ocean sub-thermocline. Based on very light _13C and very heavy _18O. Sources cited by Aze et al. 2011 (appendix S3): Coxall et al. (2000, 2007)

Phylogenetic relations
This species probably evolved from C. eocanica in the uppermost early Eocene (E7) by inflation of the digitate chambers into a terminal bulb. [Coxall & Pearson 2006]

Most likely ancestor: Clavigerinella eocanica - at confidence level 3 (out of 5). Data source: Coxall & Pearson (2006), fig 8.1.

Biostratigraphic distribution

Geological Range:
Notes: Uppermost Zone E7-E10? Due to poor sampling of suitable paleo-environments the stratigraphic range is uncertain. [Coxall & Pearson 2006]
Last occurrence (top): within E10 zone (41.89-43.23Ma, top in Lutetian stage). Data source: Coxall & Pearson (2006), fig 8.1
First occurrence (base): in upper part of E7a subzone (80% up, 48.7Ma, in Ypresian stage). Data source: Coxall & Pearson (2006), fig 8.1

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Eocene Atlas, chap. 8, p. 217

References:

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

Bolli, H. M., Loeblich, A. R. & Tappan, H. (1957). Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae and Globotruncanidae. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 3-50. gs

Coxall, H. K. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of the Hantkeninidae (Clavigerinella, Hantkenina and Cribrohantkenina). 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 8): 213-256. gs O

Coxall, H. K. (2000). Hantkeninid planktonic foraminifera and Eocene palaeoceanographic change. In, p264 (ed.) . PhD thesis, University of Bristol 1-264. gs

Loeblich, A. R. & Tappan, H. (1957b). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 173-198. gs


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Clavigerinella akersi compiled by the pforams@mikrotax project team viewed: 18-6-2024

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