Hantkenina alabamensis


Classification: pf_cenozoic -> smooth non-spinose -> Hantkeninidae -> Hantkenina -> Hantkenina alabamensis
Sister taxa: H. alabamensis, H. australis, H. compressa, H. dumblei, H. lehneri, H. liebusi, H. mexicana, H. nanggulanensis, H. primitiva, H. singanoae, H. sp.,

Taxonomy

Citation: Hantkenina alabamensis Cushman 1924
Rank: Species
Basionym: Hantkenina alabamensis
Synonyms:
Taxonomic discussion: This is the most commonly recorded species of Hantkenina and has been used to represent a wide range of morphologies. Under this taxonomy we follow a strict definition of H. alabamensis based on the distinctive holotype specimen that embodies the
relatively inflated final chamber and a swastika-like arrangement of tubulospines. We have included a variety of specimens to show the range of variability permitted to H. alabamensis (Pl.8.4); some of these are close to Hantkenina compressa (Pl.8.4, Figs. 9, 10). [Coxall & Pearson 2006]

Catalog entries: Hantkenina (Hantkenina) suprasuturalis;
Hantkenina (Hantkenina) thalmanni;
Hantkenina alabamensis;

Type images:

Short diagnosis: Hantkenina alabamensis can be distinguished from H. compressa by the greater lateral inflation of the final 1-2 chambers, the more compact and involute coiling and more forward leaning tubulospines. The species intergrades with H. compressa at the beginning of its range, but H. compressa appears stratigraphically lower and is closer in morphology to H. dumblei. It differs from H. primitiva in the greater lateral chamber inflation and by having a full complement of tubulospines in the adult whorl, and from H. nanggulanensis in the smaller size and absence of extremely globular final chambers.

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: Hantkenina alabamensis can be distinguished from H. compressa by the greater lateral inflation of the final 1-2 chambers, the more compact and involute coiling and more forward leaning tubulospines. The species intergrades with H. compressa at the beginning of its range, but H. compressa appears stratigraphically lower and is closer in morphology to H. dumblei. It differs from H. primitiva in the greater lateral chamber inflation and by having a full complement of tubulospines in the adult whorl, and from H. nanggulanensis in the smaller size and absence of extremely globular final chambers. [Coxall & Pearson 2006]

Wall type: Smooth, normal perforate and nonspinose; tubulospine surface imperforate, smooth or with fine striations. [Coxall & Pearson 2006]

Test morphology: Planispiral, compact and biumbilicate, with a quadrate or somewhat polygonal peripheral outline; 5-6 closely appressed chambers in the adult whorl, rounded to polygonal in shape and moderately inflated, becoming globular in the final stages; sutures depressed, slightly sigmoidal; umbilical regions are deep and restricted; adult chambers extend into a hollow tubulospine; primary aperture is a high equatorial arch, narrow at the top, broadening at the base into lateral lobes, bordered by an imperforate lip, often crenulated and pustulose along the margin; pustules common on early chambers of the adult whorl and in the umbilical regions; tubulospines vary from long and slender to short and stout, arising sharply from the supporting chamber from a constricted base, straight and inclined forwards in the direction of coiling, almost tangential with respect to the shell periphery in a swastika-like arrangement, positioned at the anterior chamber edge, spanning the suture between chambers, in contact with the posterior wall of the adjacent younger chamber along one third to one half of the length in final stages, distal ends taper to a point, blunt ended or terminating in a small coronet structure (Ramsay, 1962). [Coxall & Pearson 2006]

Size: Maximum diameter (excluding tubulospines) 300-600 µm. [Coxall & Pearson 2006]

Character matrix

test outline:Subpolygonalchamber arrangement:Planispiraledge view:Compressedaperture:Equatorial
umb chamber shape:Inflatedcoiling axis:N/Aperiphery:Tubulospinesaperture border:Thin lip
sp chbr shape:Inflatedumbilicus:Wideperiph margin shape:Moderately roundedaccessory apertures:Umbilical
umbilical or test sutures:Moderately depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Moderately depresseddiameter mm:0.30-0.60width mm:breadth mm:
final-whorl chambers:5.0-6.0

Biogeography and Palaeobiology


Geographic distribution: Worldwide, mid to low latitudes in open ocean and shallower shelf sites. [Coxall & Pearson 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Coxall & Pearson (2006)

Isotope paleobiology: Hantkenina alabamensis registers negative ∂18O and positive ∂13C in multispecies isotopic analysis (Poore and Matthews, 1984; Boersma and others, 1987; Coxall and others, 2000; Pearson and others, 2001; Wade and Kroon, 2002) indicating that it lived in warm waters of the surface mixed layer. [Coxall & Pearson 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): Poore & Matthews (1984); Boersma et al. (1987) Coxall et al. (2000); Pearson et al. (2001a); Wade & Kroon (2002)

Phylogenetic relations: Evolved from H. compressa in lower Zone E13. [Coxall & Pearson 2006]

Biostratigraphic distribution

Geological Range:
Notes: Lower Zone E13 to the Eocene/Oligocene boundary. [Coxall & Pearson 2006]
The LAD of Hantkenina alabamensis marks the base of zone O1/ top of E16 (Wade et al. 2011)
Last occurrence (top): at top of E16 zone (100% up, 33.9Ma, in Priabonian stage). Data source: zonal marker (Wade et al. 2011)
First occurrence (base): within E13 zone (37.99-39.97Ma, base in Bartonian 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. 230

References:

Boersma, A.; Premoli Silva, I. & Shackleton, N.J., (1987). Atlantic Eocene planktonic foraminiferal paleohydrographic indicators and stable isotope paleoceanography. Paleoceanography, 2: 287-331.

Brönnimann, P., (1950). The Genus Hantkenina Cushman in Trinidad and Barbados, B. W. I. Journal of Paleontology, 24(4): 397-420.

Coccioni, R., (1988). The genera Hantkenina and Cribrohantkenina (Foraminifera) in the Massignano section (Ancona, Italy),: Ancona II. In: Premoli Silva, I., Coccioni, R. and Montanari, A. (Editors), The Eocene-Oligocene Boundary in the Marche-Umbria Basin (Italy). International Subcommission on Paleogene Stratigraphy, Special Publication II, pp. 81-96.

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.; Pearson, P.N.; Shackleton, N.J. & Hall, M.A., (2000). Hantkeninid depth adaptation: An evolving life strategy in a changing ocean. Geology, 28: 87-90.

Cushman, J.A., (1924). A new genus of Eocene foraminifera. Proceedings of the United States National Museum, 66(2567): 1-4.

Finlay 1939 89-128 89-128 [sorry, not in our bibliography yet]

Pearson, P.N.; Norris, R.D. & Empson, A., (2001). Mutabella mirabilis gen. et sp. nov., a Miocene microperforate planktonic foraminifer with an extreme level of intraspecific variability. Journal of Foraminiferal Research, 31: 120-132.

Pearson, P.N. & others, (2001). Warm tropical sea surface temperatures in the Late Cretaceous and Eocene epochs. Nature, 413: 481-487.

Poore, R.Z. & Matthews, R.K., (1984). Oxygen isotope ranking of late Eocene and Oligocene planktonic foraminifers: implications for Oligocene sea-surface temperatures and global ice-volume. Marine Micropaleontology, 9: 111-134.

Ramsay, W.R., (1962). Hantkeninidae in the Tertiary rocks of Tanganyika. Contributions from the Cushman Foundation for Foraminiferal Research, 13: 78-89.

Rey, M., (1939). Distribution stratigraphique des Hantkenina dans le Nummulitique du Rharb (Maroc). Bulletin de la Société Géologique de France, 5: 321-341.

Thalmann, H.E., (1942). Foraminiferal genus Hantkenina and its subgenera. American Journal of Science, 240: 809-820.

Wade, B.S. & Kroon, D., (2002). Middle Eocene regional climate instability: Evidence from the western North Atlantic. Geology, 30: 1011-1014.


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Hantkenina alabamensis compiled by the pforams@mikrotax project team viewed: 23-10-2017

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