pforams@mikrotax - Hantkenina nanggulanensis pforams@mikrotax - Hantkenina nanggulanensis

Hantkenina nanggulanensis


Classification: pf_cenozoic -> Hantkeninidae -> Hantkenina -> Hantkenina nanggulanensis
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 nanggulanensis Hartono 1969
taxonomic rank: Species
Basionym: Hantkenina nanggulanensis
Synonyms:
Taxonomic discussion: This morphospecies is transitional between Hantkenina alabamensis and Cribrohantkenina inflata. The chambers of the final whorl are highly inflated, as in C. inflata, but the species lacks additional areal apertures. In some specimens the apertural opening
and surrounding lip becomes irregularly folded and invaginated to form lobes of the primary aperture (Pl.8.11, Fig. 18), a condition that probably represents the transition to the more complex multiple aperture system of Cribrohantkenina. Formerly this morphotype has usually been included in H. alabamensis; however, we observe that it is stratigraphically and morphologically distinct from the latter and thus merits specific status. Bronnimann (1950) remarked in his distinction of H. suprasuturalis that his species is generally larger and much more inflated than H. alabamensis, suggesting that it might be a prior synonym of H. nanggulanensis. However, the holotype of H. suprasuturalis is a peculiar specimen with a very angular peripheral outline and is not the typical upper Eocene morphospecies we recognise here as H. nanggulanensis, nor is it significantly more inflated than the holotype of H. alabamensis. The name nanggulanensis has rarely been used outside its type locality. We have been unable to study the holotype but the type illustrations are good and we have collected comparable specimens from the type Nanggulan Formation (see Plate 8.11). [Coxall & Pearson 2006]

Catalog entries: Hantkenina nanggulanensis

Type images:

Distinguishing features:
Parent taxon (Hantkenina): Final chambers with tubulospines
This taxon: Final 1-2 chambers globular, test large (up to 0.47 mm)

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, biumbilicate, strongly inflated and very large for the genus; 5-6 closely appressed, spherical or polygonal chambers in the adult whorl, increasing rapidly in size as added, becoming highly inflated in the final stages; peripheral outline (excluding tubulospines) is lobed or angular; adult chambers extended into a hollow tubulospine; sutures depressed and curved; umbilici deep and restricted; aperture shape is variable, laterally pinched into a narrow slit with flaring basal lobes or open and triangular, symmetrical (as is typical for earlier hantkeninids) or asymmetrical, with folds and invaginations in the margin and lip; tubulospines short and triangular or long and slender, ends tapering to a point, positioned at the anterior chamber edge, spanning the suture between chambers; arising sharply from the supporting chamber and inclined forward in the direction of coiling at a low angle almost tangential with respect to the periphery in the final stages and contacting adjacent younger chambers along their outer periphery, penultimate tubulospines may be completely enveloped by globular younger chambers. [Coxall & Pearson 2006]

Wall type:
probably nonspinose; tubulospines imperforate, smooth or with fine striations. [Coxall & Pearson 2006]

Size:
Maximum diameter of the holotype (excluding tubulospines) is 0.47 mm (Hartono, 1969). [Coxall & Pearson 2006]

Character matrix
test outline:Lobatechamber arrangement:Planispiraledge view:Planoconvexaperture:Equatorial
sp chamber shape:Inflatedcoiling axis:N/Aperiphery:Tubulospinesaperture border:Thin lip
umb chbr shape:Inflatedumbilicus: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:5-6 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution

Worldwide, low-mid latitude open-ocean and marginal paleoenvironments. [Coxall & Pearson 2006]
Aze et al. 2011 summary: Low to middle latitudes; based on Coxall & Pearson (2006)

Isotope paleobiology
Pearson and others (2001) recorded this species with isotopic values intermediate between other co-occurring species. Hantkenina spp. analyzed together from Zone P15 have lower δ18O and higher δ13C than all other species analyzed, suggesting a surface mixed-layer depth habitat (Coxall and others, 2000). [Coxall & Pearson 2006]
Aze et al. 2011 ecogroup 2 - Open ocean mixed-layer tropical/subtropical, without symbionts. Based on _13C lighter than species with symbionts; also with relatively light _18O. Sources cited by Aze et al. 2011 (appendix S3): Wade & Pearson (2008)

Phylogenetic relations
Evolved from H. alabamensis by inflation of the chambers and widening of the arched equatorial aperture in uppermost Zone E13. [Coxall & Pearson 2006]

Most likely ancestor: Hantkenina alabamensis - at confidence level 4 (out of 5). Data source: Coxall & Pearson (2006) fig 8.1.
Likely descendants: Cribrohantkenina inflata; plot with descendants

Biostratigraphic distribution

Geological Range:
Notes: Late Eocene, uppermost Zone E13 to the Eocene/Oligocene boundary. [Coxall & Pearson 2006]
Last occurrence (top): at top of E16 zone (100% up, 33.9Ma, in Priabonian stage). Data source: Coxall & Pearson (2006) fig 8.1
First occurrence (base): near top of E13 zone (90% up, 38.2Ma, in Bartonian stage). Data source: Coxall & Pearson (2006), fig. 8.1

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Eocene Atlas, chap. 8, p. 246

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 O

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

Hartono, H. M. S. (1969). Globigerina marls and their planktonic foraminifera from the Eocene of Nanggulan, Central Java. Contributions from the Cushman Foundation for Foraminiferal Research. 20(4): 152-159. gs

Pearson, P. N. & Wade, B. S. (2015). Systematic taxonomy of exceptionally well-preserved planktonic foraminifera from the Eocene/Oligocene boundary of Tanzania. Cushman Foundation for Foraminiferal Research, Special Publication. 45: 1-85. 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

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Hantkenina nanggulanensis compiled by the pforams@mikrotax project team viewed: 11-10-2024

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