Chiloguembelina wilcoxensis


Classification: pf_cenozoic -> microperforate -> Chiloguembelinidae -> Chiloguembelina -> Chiloguembelina wilcoxensis
Sister taxa: C. crinita, C. cubensis, C. midwayensis, C. morsei, C. ototara, C. parallela, C. subtriangularis, C. trinitatensis, C. wilcoxensis,

Taxonomy

Citation: Chiloguembelina wilcoxensis (Cushman and Ponton 1932)
Rank: Species
Basionym: Guembelina wilcoxensis
Synonyms:
Taxonomic discussion: The final chamber in adult Chiloguembelinawilcoxensis may be normalform to strongly kummerform. The aperture on the final chamber may be a symmetrical low to moderately high semicircular arch, centered on the chamber face and bordered by an equidimensional lip, or they may be slightly asymmetrical, off-centered on the final chamber face, and bordered by an inequidimensional lip that is slightly infolded on one side. The symmetrical shape and positioning of the aperture and equidimensional bordering lip on adult specimens of C. wilcoxensis are reminiscent of the Cretaceous Heterohelicidae. However, dissection of adult tests with symmetrical apertures in the center of the final chamber reveal that the apertures on pre-adult chambers are asymmetrical in position and shape and the bordering lip in infolded on one side. Apertural asymmetry in early ontogeny is taken to represent a primitive feature shared with the chiloguembelinid stock, whereas apertural symmetry in adult specimens is considered a derived character that first appeared in C. trinitatensis. Chiloguembelinawilcoxensis differs from this species by its larger less tapering test. [Olsson et al. 1999]

Catalog entries: Guembelina wilcoxensis;

Type images:

Short diagnosis: Distinguished by the large test size, broadly rounded periphery, rapid chamber size increase in the initial portion of the test, and symmetrically centered, low-arched to semicircular aperture surrounded by an equidimensional lip.

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: Distinguished by the large test size, broadly rounded periphery, rapid chamber size increase in the initial portion of the test, and symmetrically centered, low-arched to semicircular aperture surrounded by an equidimensional lip. [Olsson et al. 1999]

Character matrix

test outline:Subtriangularcoiling axis:N/Achamber arrangement:Biserialumbilicus:N/A
edge view:Equally biconvexumbilical or test sutures:Moderately depressedspiral sutures:N/Ashell porosity:-
wall texture:Mod. Pustuloseaperture:Terminalaperture border:Thin lipaccessory apertures:None
periphery:N/Aumb chamber shape:Inflatedsp chbr shape:N/Aperiph margin shape:Broadly rounded
umb depth:N/Adiameter mm:0.45width mm:0.35breadth mm:0.25
final-whorl chambers:2.0-2.0

Biogeography and Palaeobiology


Phylogenetic relations: Although Beckmann (1957) suggested that C. wilcoxensis descended from C. crinita during the late Paleocene, it is more likely that C. wilcoxensis was derived from C. trinitatensis during the late Paleocene since C. wilcoxensis and C. trinitatensis are more similar morphologically and study of Caribbean DSDP Site 152 indicates that the first occurrence of the latter species is older than that of the former species (B. Huber, pers. observ., 1995). Both species have a similar pustulose wall texture which suggests that they are phylogenetically related. [Olsson et al. 1999]

Biostratigraphic distribution

Geological Range:
Notes: Upper Paleocene Zone P4b through lower Eocene Zone E4. At middle latitude sites on the New Jersey coastal margin Liu and others (1997) recorded the HO of C. wilcoxensis in the middle of their Zone P6a (~Zone E2). For the southern high latitudes the LO of C. wilcoxensis was reported slightly earlier than at low latitudes, within middle Zone AP2 (~Zone P4b), and the extinction of this species marks the top of the Chiloguembelina wilcoxensis Zone (AE1) of Huber and Quille_ve_re_ (2005).
Last occurrence (top): within E3 zone (54.61-55.20Ma, top in Ypresian stage). Data source: Olsson et al. 1999
First occurrence (base): within P4 zone (57.10-60.73Ma, base in Selandian stage). Data source: Olsson et al. 1999

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 92

References:

Beckmann, J.P., (1957). Chiloguembelina Loeblich and Tappan and related foraminifera from the Lower Tertiay of Trinidad, B.W.I. . Bulletin of the United States National Museum, 215: 83-95.

Cushman, J.A. & Ponton, G.M., (1932). An Eocene foraminiferal fauna of Wilcox age from Alabama. Contributions from the Cushman Laboratory for Foraminiferal. Research, 8: 51-72.

Olsson, R.K.; Hemleben, C.; Berggren, W.A. & Huber, B.T., (1999). Atlas of Paleocene Planktonic Foraminifera. Smithsonian Contributions to Paleobiology. Smithsonian Institution Press, Washington, DC, 1-252 pp.


Chiloguembelina wilcoxensis compiled by the pforams@mikrotax project team viewed: 23-5-2017

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