Hantkenina (Aragonella) mexicana Cushman—Brönnimann, 1950:405, pl. 55: figs. 1-6 [lower and middle Eocene, figs. 1-2, 5, 6, Friendship Quarry, Trinidad; figs. 3-4, Sangrande area, Trinidad].—Ramsay, 1962:81: pl. 16: figs. 1-2, 5, 15 [lower and middle Eocene, Kilwa Masoko, Tanzania].—(sensu lato) Blow, 1979:1165 (partim), pl. 167: figs. 1-5; pl. 239: figs. 1-6 [middle Eocene Zone P11, Kilwa area, Tanzania, Sample RS.24].
Hantkenina (Aragonella) mexicanamexicana Cushman.— Blow, 1979:1166, pl. 167: figs. 1-5 [middle Eocene, Zone P11, Kilwa area, Tanzania].
Hantkeninamexicana var. aragonensis Nuttall, 1930:284, pl. 24: figs. 2-3; fig. 3 = holotype H. nuttalli Toumarkine by subsequent designation [upper Lower Eocene, Aragon Fm., La Antigua, Mexico].—Rey, 1939:323, pl. 22: fig. 3 [Lutétien supérior, Nummulitique de Rharb, Morocco].
Hantkenina (Aragonella) aragonensis Nuttall.—Thalmann, 1942:811, pl. 1: fig. 1 = pl. 24, fig. 1 of Nuttall, 1930.
Hantkeninaaragonensis Nuttall. —Subbotina, 1953:143, pl. 1: fig. 13 (refigured holotype).—Bolli and others, 1957; pl. 2: figs. 3a-b = pl. 24, fig. 3 of Nuttall (1930).— Stainforth and others, 1975:169, pl. 36: figs. 3-4 [Hantkeninaaragonensis Zone, Turkmenia, USSR].— Raju, 1968:290, pl. 1: figs.: 2, 8 [Globigerinafrontosa Zone, Karaikal, Cauvery Basin, India].
Hantkenina (Aragonella) lehneri Cushman and Jarvis.— Ramsay, 1962: 83, pl. 16: figs. 2, 5, 15 [lower and middle Eocene, Kilwa Masoko, Tanzania]. [Not Cushman and Jarvis, 1929.]
Hantkeninanuttalli Toumarkine, 1981:112, pl. 1: fig. 4 [upper Lower Eocene, Aragon Fm., La Antigua, Mexico].— Toumarkine and Luterbacher, 1985:121, pl. 23: figs. 3-5 [lower middle Eocene Hantkeninanuttalli Zone, Rio Sambre Section, Font Hill Fm., Jamaica].—Coxall and others, 2003:245, pl. 3: figs. 1, 5 [lower middle Eocene Zone P10, ODP Hole 865B, equatorial Pacific Ocean].
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]
Distinguishing features: Parent taxon (Hantkenina): Final chambers with tubulospines This taxon: Final chambers elongate; tubulospines centrally positioned; peripheral outline distinctly stellate. 4-5 chambers in the final whorl.
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
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] 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] Size: Maximum diameter (excluding tubulospines) 0.5 mm, with spines 0.75 mm or more (Cushman, 1924). [Coxall & Pearson 2006]
Character matrix
test outline:
Stellate
chamber arrangement:
Planispiral
edge view:
Compressed
aperture:
Equatorial
sp chamber shape:
Inflated
coiling axis:
N/A
periphery:
Tubulospines
aperture border:
Thin lip
umb chbr shape:
Inflated
umbilicus:
Wide
periph margin shape:
Subangular
accessory apertures:
Relict
spiral sutures:
Moderately depressed
umb depth:
Shallow
wall texture:
Smooth
shell porosity:
Finely Perforate: 1-2.5µm
umbilical or test sutures:
Moderately depressed
final-whorl chambers:
4-5
N.B. These characters are used for advanced search. N/A - not applicable
Biogeography and Palaeobiology
Geographic distributionWorldwide, 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 paleobiologyHantkeninamexicana has higher δ18O and lower δ13C 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 _13C and very heavy _18O. Sources cited by Aze et al. 2011 (appendix S3): Coxall et al. (2000); Pearson et al. (2001a) Phylogenetic relationsHantkeninamexicana 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]
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:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Histogram - Neptune occurrence data from DSDP and ODP proceedings. Pale shading <50 samples in time bin. Interpret with caution & read these notes
Primary source for this page: Coxall & Pearson 2006 - Eocene Atlas, chap. 8, p. 242
References:
Berggren, W. A., Kent, D. V., Swisher, I. , C. C. & Aubry, M. -P. (1995b). A revised Cenozoic geochronology and chronostratigraphy. In, Berggren, W. A., Kent, D. V., Aubry, M. -P. & Hardenbol, J. (eds) Geochronology, Time Scales and Global Stratigraphic Correlations. SEPM (Society for Sedimentary Geology) Special Publication No. 54, 129-212. gs
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. 2: 1-1413. gs
Bolli, H. M., Loeblich, A. R. & Tappan, H. (1957). Planktonic foraminiferal families Hantkeninidae, Orbulinidae, Globorotaliidae and Globotruncanidae. In, Loeblich, A. R. , Jr., Tappan, H., Beckmann, J. P., Bolli, H. M., Montanaro Gallitelli, E. & Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin . 215: 3-50. gs
Brönnimann, P. (1950b). The Genus Hantkenina Cushman in Trinidad and Barbados, B. W. I. Journal of Paleontology. 24(4): 397-420. 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. gsO
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
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. gs
Cushman, J. A. & Jarvis, P. W. (1929). New foraminifera from Trinidad. Contributions from the Cushman Laboratory for Foraminiferal Research. 5: 6-17. gs
Nuttall, W. L. F. (1930). Eocene Foraminifera from Mexico. Journal of Paleontology. 4: 271-293. gs
Pearson, P. N. et al. (2001a). Warm tropical sea surface temperatures in the Late Cretaceous and Eocene epochs. Nature. 413: 481-487. gs
Raju, D. S. N. (1968). Eocene-Oligocene planktonic foraminiferal biostratigraphy of Cauvery Basin, South India. Memoir of the Geological Society of India. 2: 286-299. 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
Rey, M. (1939). Distribution stratigraphique des Hantkenina dans le Nummulitique du Rharb (Maroc). Bulletin de la Société Géologique de France. 5: 321-341. gs
Rögl, F. & Egger, H. (2011). A new planktonic foraminifera species (Hantkenina gohrbandti nov. spec.) from the middle Eocene of the northwestern Tethys (Mattsee, Austria). Austrian Journal of Earth Sciences. 104: 4-14. gs
Stainforth, R. M., Lamb, J. L., Luterbacher, H., Beard, J. H. & Jeffords, R. M. (1975). Cenozoic planktonic foraminiferal zonation and characteristics of index forms. University of Kansas Paleontological Contributions, Articles. 62: 1-425. gsO
Thalmann, H. E. (1942). Foraminiferal genus Hantkenina and its subgenera. American Journal of Science. 240: 809-820. gs
Toumarkine, M. & Luterbacher, H. (1985). Paleocene and Eocene planktic foraminifera. In, Bolli, H. M., Saunders, J. B. & Perch-Neilsen, K. (eds) Plankton Stratigraphy. Cambridge Univ. Press, Cambridge 87-154. gs
Toumarkine, M. (1981). Discussion de la validité de l'espèce Hantkenina aragonensis, Nuttall, 1930; Description de Hantkenina nuttalli, n.sp. Cahiers de Micropaléontologie. 4: 109-119. gs
Hantkenina mexicana compiled by the pforams@mikrotax project teamviewed: 16-10-2024
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holotype: H. mexicana
