pforams@mikrotax - Hantkenina lehneri <title>pforams@mikrotax - Hantkenina lehneri

Hantkenina lehneri


Classification: pf_cenozoic -> Hantkeninidae -> Hantkenina -> Hantkenina lehneri
Sister taxa: H. nanggulanensis, H. alabamensis, H. primitiva, H. compressa, H. australis, H. dumblei ⟩⟨ H. lehneri, H. liebusi, H. mexicana, H. singanoae, H. sp.

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:

Distinguishing features:
Parent taxon (Hantkenina): Final chambers with tubulospines
This taxon: Final chambers elongate with tubulospines in forward position; peripheral outline distinctly stellate. 5-6 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


Emended description:


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]

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

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

Character matrix
test outline:Stellatechamber arrangement:Planispiraledge view:Compressedaperture:Equatorial
sp chamber shape:Elongatecoiling axis:N/Aperiphery:Tubulospinesaperture border:N/A
umb chbr shape:Elongateumbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
spiral sutures:Strongly depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:5.0-6.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Similar species


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 comparison with other species of the genus.

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]

Most likely ancestor: Hantkenina liebusi - at confidence level 4 (out of 5). Data source: Coxall & Pearson (2006) fig 8.1.

Biostratigraphic distribution

Geological Range:
Notes: Middle Eocene. Zone E9-E11. [Coxall & Pearson 2006]
Last occurrence (top): in upper part of E11 zone (60% up, 41Ma, in Bartonian stage). Data source: Coxall & Pearson (2006) fig 8.1
First occurrence (base): in upper part of E9 zone (60% up, 43.5Ma, in Lutetian stage). Data source: Wade et al. (2011), fig. 6

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Eocene Atlas, chap. 8, p. 237

References:

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. gs V O

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

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 V O


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Hantkenina lehneri compiled by the pforams@mikrotax project team viewed: 6-2-2023

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