Hantkenina nanggulanensis


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

Taxonomy

Citation: Hantkenina nanggulanensis Hartono 1969
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:

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


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

Test 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]

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
umb chamber shape:Inflatedcoiling axis:N/Aperiphery:Tubulospinesaperture border:Thin lip
sp chbr shape:Inflatedumbilicus:Wideperiph margin shape:Subangularaccessory apertures:None
umbilical or test sutures:Strongly depressedumb depth:Shallowwall texture:Smoothshell porosity:Finely Perforate: 1-2.5µm
spiral sutures:Strongly depresseddiameter mm:0.47width mm:breadth mm:
final-whorl chambers:5.0-6.0

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 ∂18O and higher ∂13C 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 δ13C lighter than species with symbionts; also with relatively light δ18O. 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]

Biostratigraphic distribution

Geological Range:
Notes: Late Eocene, uppermost Zone E13 to the Eocene/Oligocene boundary. [Coxall & Pearson 2006]
Last occurrence (top): within E16 zone (33.90-34.68Ma, top in Priabonian stage). Data source: Eocene Atlas
First occurrence (base): within E13 zone (37.99-39.97Ma, base in Bartonian stage). Data source: Eocene Atlas

Plot of occurrence data:

Primary source for this page: Coxall & Pearson 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 8, p. 246

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.

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.

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.

Ramsay, W.R., (1962). Hantkeninidae in the Tertiary rocks of Tanganyika. Contributions from the Cushman Foundation for Foraminiferal Research, 13: 78-89.


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Hantkenina nanggulanensis compiled by the pforams@mikrotax project team viewed: 25-9-2017

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