pforams@mikrotax - Hantkenina alabamensis <title>pforams@mikrotax - Hantkenina alabamensis

Hantkenina alabamensis


Classification: pf_cenozoic -> Hantkeninidae -> Hantkenina -> Hantkenina alabamensis
Sister taxa: H. nanggulanensis, H. alabamensis, H. primitiva, H. compressa, H. australis, H. dumblei ⟩⟨ H. lehneri, H. liebusi, H. mexicana, 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 alabamensis, Hantkenina (Hantkenina) suprasuturalis, Hantkenina (Hantkenina) thalmanni

Type images:

Distinguishing features:
Parent taxon (Hantkenina): Final chambers with tubulospines
This taxon: Final 1-2 chambers laterally inflated, coiling compact and involute, tubulospines forward leaning.

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


Emended description:


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]

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

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

Character matrix
test outline:Subpolygonalchamber arrangement:Planispiraledge view:Compressedaperture:Equatorial
sp chamber shape:Inflatedcoiling axis:N/Aperiphery:Tubulospinesaperture border:Thin lip
umb chbr shape:Inflatedumbilicus:Wideperiph margin shape:Moderately roundedaccessory apertures:Umbilical
spiral sutures:Moderately depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:5.0-6.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Similar species


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 _13C lighter than species with symbionts; also with relatively light _18O. 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]

Most likely ancestor: Hantkenina compressa - at confidence level 4 (out of 5). Data source: Coxall & Pearson (2006) fig 8.1.
Likely descendants: Hantkenina nanggulanensis; plot with descendants

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): near base of E13 zone (10% up, 39.8Ma, in Bartonian 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. 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. gs

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

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

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. gs

Finlay, H. J. (1939b). New Zealand foraminifera: Key species in stratigraphy - no. 2. Transactions of the Royal Society of New Zealand. 69(1): 89-128. gs

Pearson, P. N. & Wade, B. S. (2015). Systematic taxonomy of exceptionally well-preserved planktonic foraminifera from the Eocene/Oligocene boundary of Tanzania. Cushman Foundation for Foraminiferal Research, Special Publication. 45: 1-85. gs V O

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

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. gs

Postuma, J. A. (1971). Manual of planktonic foraminifera. Elsevier for Shell Group, The Hague. 1-406. gs

Ramsay, W. R. (1962). Hantkeninidae in the Tertiary rocks of Tanganyika. Contributions from the Cushman Foundation for Foraminiferal Research. 13(3): 79-89. gs V O

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

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

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


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Hantkenina alabamensis compiled by the pforams@mikrotax project team viewed: 6-2-2023

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