Hantkenina lehneri


Classification: pf_cenozoic -> smooth non-spinose -> Hantkeninidae -> Hantkenina -> Hantkenina lehneri
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 lehneri Cushman & Jarvis 1929
Rank: Species
Basionym: Hantkenina lehneri
Synonyms:
Taxonomic discussion: The distinctive morphology represented by Cushman and Jarvis’s holotype specimen (H. lehneri s. s.) is rare (Pl.8.8, Figs. 2, 12). We suggest that most forms recorded as H. lehneri in deep-sea core material are a closely related variant. These more commonly encountered forms also possess elongate final chambers and an incised peripheral outline. However, the test of the latter morphotype is strongly laterally compressed and the early chambers of the final whorl are more closely appressed than in the Cushman and Jarvis holotype. At the present time there are insufficient data to justify the erection of a new species and we include them in H. lehneri. [Coxall & Pearson 2006]

Catalog entries: Hantkenina lehneri;

Type images:

Short diagnosis: Hantkenina lehneri is distinguished from H. liebusi by having cylindrical, finger-like chambers in the latest growth stages, a more deeply incised and more stellate peripheral outline and, on average, one more chamber in the final whorl. It differs from H. dumblei by the higher aspect ratio of the final chambers and the more deeply incised peripheral outline. The finger-like chambers of this species are reminiscent of early examples of H. mexicana. H. lehneri can be distinguished from the earlier morphotype by the longer sutures, unequal chamber shoulders and more slender 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 lehneri is distinguished from H. liebusi by having cylindrical, finger-like chambers in the latest growth stages, a more deeply incised and more stellate peripheral outline and, on average, one more chamber in the final whorl. It differs from H. dumblei by the higher aspect ratio of the final chambers and the more deeply incised peripheral outline. The finger-like chambers of this species are reminiscent of early examples of H. mexicana. H. lehneri can be distinguished from the earlier morphotype by the longer sutures, unequal chamber shoulders and more slender tubulospines. [Coxall & Pearson 2006]

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

Test morphology: Planispiral, involute,
biumbilicate, 4½-6 appressed chambers in the final whorl, increasing rapidly in size as added; early chambers are subtriangular, final 2-3 chambers radially elongated and ‘finger-like’, each chamber of the adult whorl extends into a hollow tubulospine; peripheral outline is deeply incised, stellate; aperture is an elongated equatorial arch extending halfway up the apertural face, bordered by a well pronounced imperforate lip, which is often pustulose and crenulated along its margin; sutures are depressed, straight, becoming curved, web-like remnants of apertural lips sometimes present along sutures; umbilical region shallow, commonly pustulose, pustules extending to early chambers of final whorl; tubulospines broad based, directed radially and positioned forward of the central chamber axis toward the anterior chamber suture, posterior chamber shoulder longer than the anterior shoulder; tubulospines are not preserved in the holotype but are assumed to be comparable to those of H. liebusi and H. mexicana. [Coxall & Pearson 2006]

Size: Length (excluding tubulospines) up to 1 mm (Cushman and Jarvis,1929). [Coxall & Pearson 2006]

Character matrix

test outline:Digitatecoiling axis:N/Achamber arrangement:Planispiralumbilicus:Wide
edge view:Compressedumbilical or test sutures:Strongly depressedspiral sutures:Strongly depressedshell porosity:
wall texture:Smoothaperture:Equatorialaperture border:N/Aaccessory apertures:None
periphery:Tubulospinesumb chamber shape:Elongatesp chbr shape:Elongateperiph margin shape:Subangular
umb depth:Shallowdiameter mm:width mm:breadth mm:
final-whorl chambers:5.0-6.0

Biogeography and Palaeobiology


Geographic distribution: Hantkenina lehneri s.str. has been found in Trinidad and Tanzania. Flattened forms referable to the species have been recorded in the Northern Caucasus Mts. of Russia, Southern India and ODP Site 865, often in Zone E9 in association with Morozovelloides lehneri. [Coxall & Pearson 2006]
Aze et al. 2011 summary: Found in TrinidadTanzania and Russia; based on Coxall & Pearson (2006)

Isotope paleobiology: No data available. [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): this study

Phylogenetic relations: Hantkenina lehneri probably evolved from H. liebusi by an increase in the number of chambers in the final whorl (more evolute growth spiral), a shift of the tubulospines towards the anterior suture and an increase in radial chamber height. [Coxall & Pearson 2006]

Biostratigraphic distribution

Geological Range:
Notes: Middle Eocene. Zone E9-E11. [Coxall & Pearson 2006]
Last occurrence (top): within E11 zone (40.40-41.89Ma, top in Bartonian stage). Data source: Eocene Atlas
First occurrence (base): in upper part of E9 zone (70% 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. 237

References:

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.

Cushman, J.A. & Jarvis, P.W., (1929). New foraminifera from Trinidad. Contributions From the Cushman Foundation for Foraminiferal Reseach, 5: 6-17.

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.


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

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