Hantkenina dumblei


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

Taxonomy

Citation: Hantkenina dumblei Weinzierl & Applin 1929
Rank: Species
Basionym: Hantkenina dumblei
Synonyms:
Taxonomic discussion: Blow (1979), like Bronnimann (1950), recognized an evolutionary relationship between H. dumblei and the lower middle Eocene hantkeninids, e.g., H. mexicana, but considered it to be unrelated to later species, e.g., H. alabamensis. According to Blow, the early middle and late middle Eocene groups evolved independently from separate Pseudohastigerina ancestors. Morphometric analysis (Coxall, 2000) and stratigraphic evidence from deep-sea cores demonstrate that the H. alabamensis morphology evolved gradually from H. dumblei via the intermediate H. compressa and, thus, as argued by Pearson and others (1993), the hantkeninids are a monophyletic group. In contrast to Blow (1979) therefore, we regard H. dumblei as an intermediate morphospecies within a single continuous evolving lineage, not as the end member of an early hantkeninid radiation. [Coxall & Pearson 2006]

Catalog entries: Hantkenina dumblei;

Type images:

Short diagnosis: Hantkenina dumblei is distinguished from H. liebusi by the larger size, more continuous peripheral outline, greater number of chambers in the adult whorl and by the anterior, near sutural position of the tubulospines. It is differentiated from H. lehneri by the more continuous periphery and broad-based, triangular shape of the final whorl chambers. It is distinguished from H. compressa and H. alabamensis by two principal features. Firstly, the peripheral outline is more rapidly expanding along the radial axis, and second, chambers are usually free of contact with the tubulospine of the previous chamber, whereas in the latter species the tubulospines contact and overlap with the posterior wall of the adjacent younger chamber. In addition, tubulospines in H. dumblei are inclined at a relatively low angle, whereas in H. alabamensis they are strongly inclined with respect to the test periphery. It differs from H. australis in the larger size and having straight 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: Hantkenina dumblei is distinguished from H. liebusi by the larger size, more continuous peripheral outline, greater number of chambers in the adult whorl and by the anterior, near sutural position of the tubulospines. It is differentiated from H. lehneri by the more continuous periphery and broad-based, triangular shape of the final whorl chambers. It is distinguished from H. compressa and H. alabamensis by two principal features. Firstly, the peripheral outline is more rapidly expanding along the radial axis, and second, chambers are usually free of contact with the tubulospine of the previous chamber, whereas in the latter species the tubulospines contact and overlap with the posterior wall of the adjacent younger chamber. In addition, tubulospines in H. dumblei are inclined at a relatively low angle, whereas in H. alabamensis they are strongly inclined with respect to the test periphery. It differs from H. australis in the larger size and having straight tubulospines. [Coxall & Pearson 2006]

Wall type: Smooth, normal perforate and probably nonspinose; tubulospine surface smooth or with fine spiral striations, imperforate or perforated by small sparsely distributed pores. [Coxall & Pearson 2006]

Test morphology: Planispiral, involute, biumbilicate and laterally compressed; 5-7 chambers in the final whorl, expanding and lengthening rapidly as added; chambers subtriangular, closely appressed and in contact with each other along their entire radial length; each chamber of the final whorl extends into a hollow tubulospine; aperture is an elongated equatorial arch, extending about halfway up the apertural face, widening towards the base into weak basal lobes, bordered by an imperforate flaring lip; sutures depressed, straight, becoming sigmoidal with small web-like remnants of relict apertures sometimes present within them; tubulospines short and stout on early chambers, becoming long and slender in later stages, sometimes extremely long, arising sharply from the supporting chamber wall, inclined forward slightly in the direction of coiling (~45 degrees), positioned close to or at the anterior chamber suture; anterior chamber shoulder is nonexistent giving weak incisions between chambers, distal ends taper into fine points, unornamented or with very small finger-like projections (coronet structure of Ramsay, 1962), a small terminal aperture opening from the axial canal can sometimes be observed the adult chambers of well preserved specimens. [Coxall & Pearson 2006]

Size: Maximum diameter (excluding tubulospines)400-900 µm. [Coxall & Pearson 2006]

Character matrix

test outline:Lobatecoiling axis:N/Achamber arrangement:Planispiralumbilicus:Wide
edge view:Compressedumbilical or test sutures:Moderately depressedspiral sutures:Moderately depressedshell porosity:Finely Perforate: 1-2.5
wall texture:Smoothaperture:Terminalaperture border:Thin flangeaccessory apertures:Relict
periphery:Tubulospinesumb chamber shape:Subtriangularsp chbr shape:Subtriangularperiph margin shape:Subangular
umb depth:Shallowdiameter mm:0.40-0.90width mm:breadth mm:
final-whorl chambers:5.0-7.0

Biogeography and Palaeobiology


Geographic distribution: This species has a global distribution in mid-low latitudes. It occurs in abundance at ODP Site 865 in Zones E10-E11 in association with Hantkenina lehneri and Morozovelloides lehneri. It has also been found at relatively high northerly latitudes compared to other hantkeninid species, e.g. ODP Site 647 (North Atlantic) in association with H. australis. [Coxall & Pearson 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Coxall & Pearson (2006)

Isotope paleobiology: Hantkenina dumblei has higher ∂18O and lower ∂13C than Morozovelloides and a similar isotopic signature to Turborotalia frontosa (Pearson and others, 1993, 2001; Coxall and others, 2000), suggesting a deep to intermediate depth habitat. This is supported by the boron isotope data of Pearson and Palmer (1999). There is no ∂13C enrichment trend with increasing test size. [Coxall & Pearson 2006]
Aze et al. 2011 ecogroup 3 - Open ocean thermocline. Based on light δ13C and relatively heavy δ18O. Sources cited by Aze et al. 2011 (appendix S3): Pearson et al. (1993, 2001a); Coxall & Pearson (2006)

Phylogenetic relations: Hantkenina dumblei evolved from H. liebusi by an increase in the rate of chamber expansion, closer appression of the chambers and forward migration of the tubulospines. It is closely related to H. compressa, which is intermediate between this form and H. alabamensis. [Coxall & Pearson 2006]

Biostratigraphic distribution

Geological Range:
Notes: Middle Eocene, mid Zone E9 to mid E13. [Coxall & Pearson 2006]
Last occurrence (top): within E13 zone (37.99-39.97Ma, top in Bartonian stage). Data source: Eocene Atlas
First occurrence (base): in upper part of E9 zone (80% up, 43.4Ma, 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. 236

References:

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., (2000). Hantkeninid planktonic foraminifera and Eocene palaeoceanographic change. PhD Thesis, University of Bristol, unpublished, 264 pp.

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. & Siegfus, S.S., (1939). Some new and interesting foraminifera from the Kreyenhagen shale of California. Contributions from the Cushman Laboratory for Foraminiferal Research, 15: 32.

Pearson, P.N. & Palmer, M.R., (1999). Middle Eocene seawater pH and atmospheric carbon dioxide concentrations. Science, 284: 1824-1826.

Pearson, P.N.; Shackleton, N.J. & Hall, M.A., (1993). Stable isotope paleoecology of middle Eocene planktonic foraminifera and multi-species isotope stratigraphy, DSDP Site 523, South Atlantic. Journal of Foraminiferal Research, 23: 123-140.

Rajshekhar 1992 [sorry, not in our bibliography yet]tep

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.

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

Weinzierl, L.L. & Applin, E.R., (1929). The Claiborne Formation on the Coastal Domes. Journal of Paleontology, 3(4): 384-410.


Hantkenina dumblei compiled by the pforams@mikrotax project team viewed: 28-3-2017

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