Tenuitella praegemma


Classification: pf_cenozoic -> Globigerinitidae -> Tenuitella -> Tenuitella praegemma
Sister taxa: T. iota, T. fleisheri, T. parkerae, T. clemenciae, T. angustiumbilicata, T. munda, T. gemma, T. praegemma, T. patefacta, T. insolita, T. sp.,

Taxonomy

Citation: Tenuitella praegemma Li 1987
Rank: Species
Basionym: Praetenuitella praegemma
Synonyms: [synonymy from Huber et al. 2006, updated from Pearson et al. 2018]
Taxonomic discussion: The holotype of T. praegemma is re-illustrated on Plate 16.6, Figs. 1-3 along with specimens from the upper Eocene of the New Jersey coastal margin, including specimens previously designated as Globorotalia gemma by Poore and Bybell (1988) (Pl.16.6, Figs. 4, 5, 14) and P. praegemma forma pendulocamerata by Poag and Commeau (1995) (Pl.16.6, Figs. 15-19). The very elongate interiomarginal apertural slit that extends from an extraumbilical position across the periphery and sometimes to the spiral side is a characteristic feature of this species. Some forms are biapertural (Pl.16.6, Figs. 11, 16, 18) and others show presence of a secondary apertural lip on the spiral suture (Pl.16.6, Figs. 12, 13). [Huber et al. 2006]

A monolamellar microstructure in T. praegemma is revealed from SEM observation (Pl.16.6, Fig. 9) and is also suggested that T. praegemma descended from T. insolita during the late Eocene. It is also possible that it descended from T. patefacta since there is greater similarity in the apertures of praegemma and patefacta than that of insolita. [Huber et al. 2006]

Catalog entries: Praetenuitella praegemma,

Type images:

Distinguishing features: Like T. insolita but aperture is low and extends from near the umbilicus to the spiral side and may be divided in two.

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


Diagnostic characters: Distinguished from other tenuitellids by having either a low, interiomarginal aperture that extends from near the umbilicus to the spiral side or by presence of a low, narrow extraumbilical aperture accompanied by a supplementary aperture (or apertural lip) on or near the peripheral margin of the spiral suture; it further differs from Tenuitella gemma by having a more lobate equatorial outline. [Huber et al. 2006]

Wall type: Microperforate, surface smooth to finely pustulose, pustules irregularly scattered on umbilical and spiral sides of test. [Huber et al. 2006]

Test morphology: Test small, lobate circular in equatorial outline, equatorial periphery rounded; chambers globular, coiled in a low trochospire, increasing gradually in size, 4-5 in the final whorl, subcrescentic on spiral side, final chamber may be narrow, asymmetrical and pendulous; sutures depressed, curved on the spiral side, radial on umbilical side; umbilicus narrow, deep; aperture a low extraumbilical-umbilical arch bordered by a narrow, equidimensional lip that may extends to the spiral side, and may be accompanied by a secondary aperture or apertural lip along the spiral suture. [Huber et al. 2006]

Size: Holotype maximum diameter: 0.16 mm. [Huber et al. 2006]

Character matrix

test outline:Lobatechamber arrangement:Trochospiraledge view:Equally biconvexaperture:Extraumbilical-peripheral
sp chamber shape:Globularcoiling axis:Lowperiphery:N/Aaperture border:Thin lip
umb chbr shape:Globularumbilicus:Wideperiph margin shape:Broadly roundedaccessory apertures:Sutural
spiral sutures:Strongly depressedumb depth:Shallowwall texture:Finely pustuloseshell porosity:Microperforate: <1µm
umbilical or test sutures:Strongly depressedfinal-whorl chambers:4.0-5.0 N.B. These characters are used for advanced search. N/A - not applicable

Biogeography and Palaeobiology


Geographic distribution: North Atlantic margin. [Huber et al. 2006]

Isotope paleobiology: Oxygen and carbon isotope data obtained for T. praegemma (Fig. 16.3) demonstrate that this species has very similar values as the co-occurring benthic Cibicidoides spp. and is 1.32‰ more positive in ∂18O and 1.32‰ more negative in ∂13C than the co-occurring planktonic species Turborotalia ampliapertura. These results suggest that T. praegemma was a relatively deep dwelling planktonic species that either preferred living within the oxygen minimum zone of the water column or had a considerable vital effect causing preferential fractionation of the lighter carbon isotope. [Huber et al. 2006]

Phylogenetic relations: It is suggested that T. praegemma descended from T. insolita during the late Eocene. It is also possible that it descended from T. patefacta since there is greater similarity in the apertures of praegemma and patefacta than that of insolita. [Huber et al. 2006]

Most likely ancestor: Tenuitella insolita - at confidence level 2 (out of 5). Data source: Huber et al. 2006 f16.2.
Likely descendants: Tenuitella gemma;

Biostratigraphic distribution

Geological Range:
Notes: Upper Eocene to lowermost Oligocene; Zones E15-O1. [Huber et al. 2006]
Last occurrence (top): within O1 zone (32.10-33.90Ma, top in Rupelian stage). Data source: Huber et al. 2006 f16.2
First occurrence (base): within E15 zone (34.68-35.89Ma, base in Priabonian stage). Data source: Huber et al. 2006 f16.2

Plot of occurrence data:

Primary source for this page: Pearson et al. 2018 - Olig Atlas chap.16 p.454; Huber et al. 2006 - Eocene Atlas, chap. 16, p. 491

References:

BouDagher-Fadel, M. K. (2012). Biostratigraphic and Geological Significance of Planktonic Foraminifera (1st Edition). Elsevier., . 1-319. gs

Huber, B. T., Olsson, R. K. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of Eocene microperforate planktonic foraminifera (Jenkinsina, Cassigerinelloita, Chiloguembelina, Streptochilus, Zeauvigerina, Tenuitella, and Cassigerinella) and Problematica (Dipsidripella). 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: 461-508. gs

Li, Q. (1987). Origin, phylogenetic development and systematic taxonomy of the Tenuitella plexus (Globigerinitidae, Globigerininina). Journal of Foraminiferal Research. 17: 298-320. gs

Pearson, P. N., Wade, B. S. & Huber, B. T. (2018c). Taxonomy, biostratigraphy, and phylogeny of Oligocene Globigerinitidae (Dipsidripella, Globigerinita, and Tenuitella). In, Wade, B. S. , Olsson, R. K. , Pearson, P. N. , Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication. 46: 429-459. gs

Poag, C. W. & Commeau, J. A. (1995). Paleocene to middle Miocene planktic foraminifera of the southwestern Salisbury Embayment, Virginia and Maryland: Biostratigraphy, allostratigraphy, and sequence stratigraphy. Journal of Foraminiferal Research. 25: 134-155. gs

Poore, R. Z. & Bybell, L. M. (1988). Eocene to Miocene biostratigraphy of New Jersey Core ACGS #4: Implications for regional stratigraphy. U.S. Geological Survey Bulletin. 1829: 1-41. gs


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Tenuitella praegemma compiled by the pforams@mikrotax project team viewed: 24-7-2019

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