Hantkenina


Classification: pf_cenozoic -> smooth non-spinose -> Hantkeninidae -> Hantkenina
Sister taxa: Cribrohantkenina, Hantkenina, Clavigerinella,
Daughter taxa (blue => in age window 0-300Ma)
final chambers (sub)triangular
Final 1-2 chambers globular, test large (up to 0.47 mm)
Final 1-2 chambers laterally inflated, coiling compact and involute, tubulospines forward leaning.
Like H. compressa but tubulospines absent on early adult chambers and test generally smaller test
Final chambers triangular, with nearly continuous peripheral outline; tubulospines in the trans-sutural position and with forward-inclined orientation.
Species showing features of H. dumblei and H. compressa, but unique in having posteriorly recurved tubulospines.
Final chambers triangular, with nearly continuous peripheral outline, tubulospines in anterior (near sutural) position.
final chambers elongate
Final chambers elongate with tubulospines in forward position; peripheral outline distinctly stellate. 5-6 chambers in the final whorl.
Like H. mexicana but with more compressed test, less stellate peripheral outline, and tubulospines in a more forward position. 4½-6 chambers in the final whorl.
Final chambers elongate; tubulospines centrally positioned; peripheral outline distinctly stellate. 4-5 chambers in the final whorl.
Final chambers very elongate with rudimentary terminal cylindrical extensions, but lacking true tubulospines. 4-5 chambers in the final whorl.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Hantkenina Cushman, 1924
Rank: Genus
Type species: Hantkenina alabamensis Cushman, 1924.
Synonyms:
Taxonomic discussion: We regard Hantkenina as a monophyletic genus and do not support Blow’s (1979) view that the early middle Eocene and late middle Eocene to late Eocene species were separately derived. Although the shells are compressed and planispiral, the earliest morphotypes (H. singanoae and H. mexicana) show signs of asymmetry in aperture shape and in the distribution of pre-adult whorls on one or other side of the shell. This feature, which is also seen in the sister genus Clavigerinella, testifies to a trochospiral ancestry.
[Coxall & Pearson 2006]

Catalog entries: Hantkenina;

Type images:

Short diagnosis: Final chambers with tubulospines

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: The most prominent feature of Hantkenina is the presence of tubulospines, which distinguish it from the ancestral genus Clavigerinella. Tubulospines also occur in closely related Cribrohantkenina, which differs from Hantkenina in having a multiple areal aperture system. The Cretaceous genus Schackoina, which is the only other planktonic foraminiferal genus to possess tubulospines, is readily distinguished from Hantkenina by having a microperforate wall, fewer chambers and much smaller test size (0.63-1.50 mm).
[Coxall & Pearson 2006]

Wall type: Smooth, normal perforate, probably nonspinose. [Coxall & Pearson 2006]

Test morphology: Planispiral, biumbilicate or showing a subtly raised spiral side and very shallow umbilicus; 4-7 chambers in the final whorl; chambers rounded in the early stages, adult chambers radially elongated, triangular, polygonal or spherical, laterally compressed or highly inflated; some or all of the adult chambers extend into hollow non-porous tubulospines, of variable length, shape and orientation, or, in the case of H. singanoae n. sp., the chambers possess a distinct terminal nub or porous “proto-tubulospine”; peripheral outline (excluding tubulospines) varies from stellate, with deep incisions between chambers, to angular, smooth-continuous or gently lobed; the aperture is a single equatorial arch bordered by a distinctive lip of variable width, symmetrical or slightly asymmetrical.
[Coxall & Pearson 2006]

Biogeography and Palaeobiology


Phylogenetic relations: Hantkenina evolved gradually from Clavigerinella caucasica in the latest early Eocene (Coxall and others, 2003). It gave rise to Cribrohantkenina in the late Eocene and the entire family went extinct at the Eocene/Oligocene boundary (33.7 Ma). [Coxall & Pearson 2006]

Most likely ancestor: Clavigerinella - at confidence level 4 (out of 5). Data source: Coxall & Pearson 2006.

Biostratigraphic distribution

Geological Range:
Last occurrence (top): at top of Priabonian Stage (100% up, 33.9Ma, in Priabonian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Lutetian Stage (57% up, 44Ma, in Lutetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 8, p. 229

References:

Bermudez, P.J., (1937). Nuevas especies de Foraminiferos del Eoceno de las cercanias de Guanajay, provincia Pinar del Rio, Cuba. Memorias de la Sociedad Cubana de Historia Natural, 11(4): 237-248.

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.

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

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.; Huber, B.T. & Pearson, P.N., (2003). Origin and morphology of the Eocene planktonic foraminifera Hantkenina. Journal of Foraminiferal Research, 33: 237-261.

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

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


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Hantkenina compiled by the pforams@mikrotax project team viewed: 17-12-2017

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