Hantkenina mexicana


Classification: pf_cenozoic -> smooth non-spinose -> Hantkeninidae -> Hantkenina -> Hantkenina mexicana
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 mexicana Cushman 1924
Rank: Species
Basionym: Hantkenina mexicana
Synonyms:
Taxonomic discussion: We regard H. mexicana as a senior synonym of H. nuttalli Toumarkine, 1981. Various authors have used Toumarkine’s (1981) concept of H. nuttalli to represent ‘primitive-looking’ early hantkeninids with digitate chambers and stout, broad based tubulospines. Although there may be a case for distinguishing these forms we have been unable to consistently recognize these morphologic differences in populations of early hantkeninids. Moreover, the holotype of H. nuttalli (one of three H. aragonensis syntypes selected by Nuttall, 1930) does not clearly demonstrate the features claimed by Toumarkine’s (1981) description (i.e. large, inflated chambers, which taper more gradually into the terminal spines) because all the tubulospines have broken off. Therefore, following Blow (1979) we adopt a broad sense of H. mexicana to include the spectrum of early stellate hantkeninid morphologies from their origin at the base of the middle Eocene. However, we do recognize a new species transitional from Clavigerinella to Hantkenina, namely H. singanoae n. sp. (see below). [Coxall & Pearson 2006]

Catalog entries: Hantkenina mexicana;
Hantkenina mexicana aragonensis;
Hantkenina nuttalli;

Type images:

Short diagnosis: Hantkenina mexicana is distinguished from H. liebusi by the more central position of the tubulospines on each chambers. The peripheral outline of H. mexicana is also more distinctly stellate. It differs from H. lehneri (sensu stricto), which also has elongate ‘finger-like’ chambers, by having a more deeply incised peripheral outline and fewer chambers in the final whorl.

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 mexicana is distinguished from H. liebusi by the more central position of the tubulospines on each chambers. The peripheral outline of H. mexicana is also more distinctly stellate. It differs from H. lehneri (sensu stricto), which also has elongate ‘finger-like’ chambers, by having a more deeply incised peripheral outline and fewer chambers in the final whorl. [Coxall & Pearson 2006]

Wall type: Smooth, normal perforate and probably nonspinose; tubulospines imperforate or with small, scattered pores, smooth or finely striated with a well-defined zone of demarcation between the tubulospines and the chamber wall. [Coxall & Pearson 2006]

Test morphology: Planispiral, evolute, biumbilicate or showing a slightly raised spiral side and very shallow umbilicus; laterally compressed with 4-5 rapidly expanding chambers in the final whorl; final whorl chambers radially elongate or digitate, well separated, inflated peripherally and more compressed within the umbilical region; some specimens, including the holotype, exhibit anterior flexure of the final chamber; peripheral outline distinctly stellate; each chamber of the adult whorl extends gradually into a hollow tubulospine; aperture is a narrow, elongate equatorial arch bordered by an imperforate flaring lip, often with a crenulated and/or pustulose margin, relict apertural lips are sometimes preserved as webs along the sutures; sutures straight, becoming curved in the final stages, only partially contacting adjacent chamber; tubulospines variable in form, broad-based and stout or long and slender, positioned centrally with respect to the radial chamber axis, directed radially between anterior and posterior chamber shoulders, distal ends usually blunt and closed (although it is possible that a terminal aperture existed in life) and commonly possess terminal finger-like projections (coronet structure of Ramsay, 1962). [Coxall & Pearson 2006]

Size: Maximum diameter (excluding tubulospines) 0.5 mm, with spines 0.75 mm or more (Cushman, 1924). [Coxall & Pearson 2006]

Character matrix

test outline:Stellatechamber arrangement:Planispiraledge view:Compressedaperture:Equatorial
umb chamber shape:Inflatedcoiling axis:N/Aperiphery:Tubulospinesaperture border:Thin lip
sp chbr shape:Inflatedumbilicus:Wideperiph margin shape:Subangularaccessory apertures:Relict
umbilical or test sutures:Moderately depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Moderately depresseddiameter mm:0.75width mm:breadth mm:
final-whorl chambers:4.0-5.0

Biogeography and Palaeobiology


Geographic distribution: Worldwide, restricted to low latitudes. Usually rare in open ocean sections and, thus, has been an unreliable marker for the base of planktonic foraminiferal Zone P10 (Berggren and others, 1995). Common in ODP Site 865, Mexico, US Gulf Coast and coastal Tanzania sections. [Coxall & Pearson 2006]
Aze et al. 2011 summary: Low latitudes; based on Coxall & Pearson (2006)

Isotope paleobiology: Hantkenina mexicana has higher ∂18O and lower ∂13C than all other co-occurring planktonic species, including the subbotinids, indicating a cold, deep, possibly sub-thermocline habitat (Coxall and others, 2000; Pearson and others, 2001). A sample analyzed by Boersma and others (1987) as H. aragonensis had isotopic ratios similar to co-occurring subbotinids. [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); Pearson et al. (2001a)

Phylogenetic relations: Hantkenina mexicana evolved from H. singanoae by lengthening of the terminal protrusion into a straight, imperforate hollow tubulospine. It gave rise to H. liebusi by reduction in chamber height and a shift in the position of the tubulospines towards the anterior suture. [Coxall & Pearson 2006]

Biostratigraphic distribution

Geological Range:
Notes: Lower middle Eocene. Base of Zone E8 to E9. [Coxall & Pearson 2006]
Last occurrence (top): in upper part of E9 zone (80% up, 43.4Ma, in Lutetian stage). Data source: Wade et al. (2011), fig. 6
First occurrence (base): at base of E9 zone (0% up, 43.9Ma, in Lutetian stage). Data source: Wade et al. (2011), fig. 6

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 8, p. 242

References:

Berggren, W.A.; Kent, D.V.; Swisher, I., C.C. & Aubry, M.-P., (1995). A revised Cenozoic geochronology and chronostratigraphy. In: Berggren, W.A. et al. (Editors), Geochronology, Time Scales and Global Stratigraphic Correlations. SEPM (Society for Sedimentary Geology) Special Publication No. 54.

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.

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.; 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.

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. & Jarvis, P.W., (1929). New foraminifera from Trinidad. Contributions from the Cushman Laboratory for Foraminiferal Research, 5: 6-17.

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

Nuttall, W.L.F., (1930). Eocene Foraminifera from Mexico. Journal of Paleontology, 4: 271-293.

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

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.

Raju, D.S.N., (1968). Eocene-Oligocene planktonic foraminiferal biostratigraphy of Cauvery Basin, South India. Geological Society of India, 2: 286-299.

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.

Stainforth, R.M.; Lamb, J.L.; Luterbacher, H.; Beard, J.H. & Jeffords, R.M., (1975). Cenozoic planktonic foraminiferal zonation and characteristics of index forms. The University of Kansas Paleontological Contributions, 62: 1-425.

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

Toumarkine, M. & Luterbacher, H., (1985). Paleocene and Eocene planktic foraminifera. Plankton Stratigraphy. Cambridge Univ. Press, Cambridge, 87-154 pp.

Toumarkine, M., (1981). Discussion de la validite de l'espece Hantkenina aragonensis, Nuttall, 1930; Description de Hantkenina nuttalli, n.sp. Ver Freunde Naturg Mecklenburg, Archiv, Jahrg. (1896), 4: 109-119.


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Hantkenina mexicana compiled by the pforams@mikrotax project team viewed: 25-9-2017

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