Clavigerinella akersi


Classification: pf_cenozoic -> smooth non-spinose -> 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
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:

Short diagnosis: Final chambers with bulbous terminal swellings

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: Clavigerinella akersi is distinguished from other species of Clavigerinella by having bulbous terminal swellings in the final 1-3 chambers. According to Blow (1979) there is also swelling at the base of the chambers but this also occurs in C. eocanica. It is distinguished from Parasubbotina prebetica by the planispiral coiling, lateral compression of the test, rapidly lengthening chambers and fully equatorial position of the aperture. [Coxall & Pearson 2006]

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

Test 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]

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:Digitatechamber arrangement:Planispiraledge view:Compressedaperture:Umbilical
umb chamber shape:Digitatecoiling axis:N/Aperiphery:N/Aaperture border:Thick lip
sp chbr shape:Digitateumbilicus:Wideperiph margin shape:Moderately roundedaccessory apertures:Relict
umbilical or test sutures:Weakly depressedumb depth:Shallowwall texture:shell porosity:
spiral sutures:Weakly depresseddiameter mm:0.86width mm:breadth mm:0.23
final-whorl chambers:2.0-4.0

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 ∂18O and low ∂13C 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 δ13C and very heavy δ18O. 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]

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: Eocene Atlas
First occurrence (base): within E7 zone (45.72-50.20Ma, base in Ypresian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 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, 1413 pp.

Bolli, H.M.; Loeblich, A.R., Jr. & Tappan, H., (1957). Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae and Globotruncanidae. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, DC, pp. 3-50.

Coxall, H.K. & Pearson, P.N., (2006). Taxonomy, biostratigraphy, and phylogeny of the Hantkeninidae (Clavigerinella, Hantkenina and Cribrohantkenina). In: Pearson, P.N. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Allen Press, Lawrence, Kansas, pp. 213-256.

Coxall, H.K., (2000). Hantkeninid planktonic foraminifera and Eocene palaeoceanographic change. PhD Thesis, University of Bristol, unpublished, 264 pp.

Loeblich, A.R., Jr. & Tappan, H., (1957). Planktonic foraminifera of Paleocene and early Eocene Age from the Gulf and Atlantic coastal plains. In: Loeblich, A.R., Jr. et al. (Editors), Studies in Foraminifera, U.S. National Museum Bulletin 215. U.S. Government Printing Office, Washington, D.C., pp. 173-198.

Loeblich, A.R. & Tappan, H., (1957). Woodringina, a new foraminiferal genus (Heterohelicidae) from the Paleocene of Alabama. Journal of the Washington Academy of Sciences., 47: 39-40.


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Clavigerinella akersi compiled by the pforams@mikrotax project team viewed: 24-9-2017

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