Chiloguembelina


Classification: pf_cenozoic -> Guembelitrioidea -> Chiloguembelinidae -> Chiloguembelina
Sister taxa: Chiloguembelina, Streptochilus,
Daughter taxa: - species arranged by first occurrence (blue => in age window 0-800Ma)
Oligocene/Late Eocene species
Like C. cubensis but test outline more rapidly flaring, greater apical angle of about 55-60°, a more rapid increase in chamber size and generally a shorter and wider test.
Like C. ototara but with fine costae parallel to the long axis of the test.
Like C. ototara but with smooth microperforate wall texture.
Test short to somewhat elongate, moderately to rapidly expanding, subtriangular, periphery rounded rather than compressed; usually 11-12, up to 15 chambers; sutures depressed, perpendicular to slightly oblique to growth axis; Aperture moderately narrow to broad symmetrical arch centered or slightly off-center, bordered on one side by a narrow lip.
Early Eocene species
Test short and thick, tapering rapidly toward its base. Aperture centrally located, symmetrical, high and narrow.
Test biserial with chambers that increase uniformly in breadth and height. Aperture symmetrically centered, low-arched with a narrow, equidimensional lip.
Test large, with broadly rounded periphery, rapid chamber size increase in the initial portion of the test. Aperture symmetrically centered, low-arched to semicircular with an equidimensional lip.
Test biserial throughout; aperture is marked by a narrow lip, infolded on one side, and expanded into a distinct apertural flange on the opposite side. Later chambers are subglobular. The sutures distinct and depressed. Test microperforate and last chambers finely hispid.
Paleocene species
Test small, biserial with subangular periphery, subtriangular in side view. Chambers, slightly inflated,broadening though ontogeny, successive chambers slightly overlapping the previous one. Sutures nearly straight, at low angle with the growth axis. Aperture low, asymmetric arch with lip that narrows toward the center of the chamber. 
Test small, compressed, and rapidly tapering. Early chambers subspherical, later chambers are broadercross the coiling axis and overlap the immediately preceding chambers, can extend almost across test. Aperture of each chamber exhibits only one distinct lateral flange
The test biserial throughout. Sutures are distinct and depressed, initially sub-horizontal, oblique between later chambers. Successive chambers overlap, particularly in late ontogeny. Initial chambers sub-spherical, later chambers broader Wall surface with numerous small pustules, especially on early chambers. Aperture with a single distinct lateral flange.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Chiloguembelina Loeblich and Tappan, 1956
Rank: Genus
Type species: Guembelina midwayensis Cushman, 1940
Taxonomic discussion: The microperforate surface texture, apertural asymmetry, and twisted coiling axis are the primary features that unite Chiloguembelina species with woodringinids and other Paleocene descendants of Guembelitria cretacea. The biserial first whorl of Chiloguembelina species distinguishes them from Woodringina species.
Beckmann (1957) proposed that Guembelina trinitatensis Cushman and Renz and Guembelina wilcoxensis Cushman and Ponton descended from Chiloguembelina crinita (Glaessner). On this basis, Beckmann (1957) assigned trinitatensis and wilcoxensis to the genus Chiloguembelina. [Olsson et al. 1999]

Catalog entries: Chiloguembelina,

Distinguishing features: Test subtriangular in outline, biserial throughout or rarely with multiserial final chambers; aperture a simple arched opening at base of the final chamber, with a narrow rim on one margin and a broad collar or flange directed toward one of the flat sides of the test, lacking an infolded margin or internal plate. Rarely with multiple apertures.

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: The original description is diagnostic of many Chiloguembelina species (i.e., Chiloguembelina midwayensis (Cushman, 1940), C. crinita (Glaessner, 1937b), and C. morsei (Kline, 1943)). The diagnostic characters of Chiloguembelina species include the microperforate surface texture, slight twisting of the coiling axis, and infolding of the apertural lip on one side. The apertural flap noted by Loeblich and Tappan (1956) and Reiss (1963) characterizes C. midwayensis and closely related taxa (C. morsei and C. crinita). This flap is located on the apertural side that is not infolded and results from extension of the apertural lip (and its trailing chamber wall) over the preceding chamber. The apertural infolding and opposing flap render the chiloguembelinid aperture distinctly asymmetric with respect to the plane of biserial symmetry. This apertural asymmetry and twisting of the coiling axis are much reduced in the late Paleocene taxa Chiloguembelina trinitatensis (Cushman and Renz, 1942) and Chiloguembelina wilcoxensis (Cushman and Ponton, 1932). Apertural asymmetry is variably expressed in C. wilcoxensis; although apertural asymmetry occurs in early ontogeny, the apertures of terminal chambers appear to be symmetric in some C. wilcoxensis specimens and asymmetric in others (Plate 70: Figures 11, 12, 16, 17). [Olsson et al. 1999]

Wall type: Bilamellar, generally microperforate, though low latitude forms may have larger pores; wall texture smooth, finely to moderately pustulose, or finely striate; [Eocene Atlas]

Test morphology: Test subtriangular in outline, biserial throughout or rarely with multiserial final chambers, initial chambers sometimes slightly twisting; chambers slightly to moderately inflated, increasing slowly to moderately in size; aperture a simple arched opening at base of the final chamber, symmetrically or asymmetrically centered on chamber face, with an inturned, narrow bordering rim on one margin and a broad collar or flange that is directed toward one of the flat sides of the test, lacking an infolded margin or internal plate. Multiple apertures rarely occur on specimens assigned to this genus.
[Eocene Atlas]

Biogeography and Palaeobiology


Phylogenetic relations: Descended from Woodringina by loss of the initial triserial coiling (Olsson and others, 1999).
[Eocene Atlas]

Similar species: Differs from Heterohelix Ehrenberg (1843) and Laeviheterohelix Nederbragt (1991) by the presence of an asymmetric infolding of the apertural collar; differs from Streptochilus Bronnimann and Resig (1971) by having a narrower and more equal thickness of the apertural collar, lacking an internal plate connecting successive foramina of all chambers, and by having a surface texture that is pustulose or striate rather than smooth to granular. Pore mounds are not present on any species of Chiloguembelina.
[Eocene Atlas]

Most likely ancestor: Woodringina - at confidence level 4 (out of 5). Data source: Olsson et al, 1999 f6.

Biostratigraphic distribution

Geological Range:
Notes: Lower Danian through middle Oligocene (Zones P -O4).
[Eocene Atlas]
Last occurrence (top): in lower part of Chattian Stage (23% up, 26.9Ma, in Chattian stage). Data source: Total of range of species in this database
First occurrence (base): at base of Danian Stage (0% up, 66Ma, in Danian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Olsson et al. 1999 - Atlas of Paleocene Planktonic Foraminifera, p. 89

References:

Beckmann, J. P. (1957). Chiloguembelina Loeblich and Tappan and related foraminifera from the Lower Tertiay of Trinidad, B.W.I. In, Loeblich, A. R. , Jr. , Tappan, H. , Beckmann, J. P. , Bolli, H. M. , Montanaro Gallitelli & E. Troelsen, J. C. (eds) Studies in Foraminifera. U.S. National Museum Bulletin. 215: 83-95. gs

Brönnimann, P. & Resig, J. (1971). A Neogene globigerinacean biochronologic time-scale of the southwestern Pacific. Initial Reports of the Deep Sea Drilling Project. 7(2): 1235-1469. gs

Cushman, J. A. (1940). Midway foraminifera from Alabama. Contributions from the Cushman Laboratory for Foraminiferal Research. 16: 51-73. gs

Ehrenberg, C. G. (1843b). Verbreitung und Einfluss des mikroscopischen Lebens in Süd- und Nord Amerika. Bericht k. preuss. Akad. Wiss. Berlin. 1841: 291-446. gs

El-Naggar, Z. R. (1971a). On the classification, evolution and stratigraphical distribution of the Globigerinacea. In, Farinacci, A. (ed.) Proceedings of the II Planktonic Conference, Roma 1970. Edizioni Tecnoscienza, Rome 421-476. 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

Loeblich, A. R. & Tappan, H. (1956). Chiloguembelina, a new Tertiary genus of the Heterohelicidae (Foraminifera). Journal of the Washington Academy of Sciences. 46: 340-. gs

Nederbragt, A. J. (1991). Late Cretaceous biostratigraphy and development of Heterohelicidae (planktic foraminifera). Micropaleontology. 37: 329-372. gs

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

Smart, C. W. & Thomas, E. (2007). Emendation of the genus Streptochilus Brönnimann and Resig 1971 (Foraminifera) and new species from the lower Miocene of the Atlantic and Indian Oceans. Micropaleontology. 53(01-Feb): 73-103, 103 figures, 113 lates, 101 table. gs


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Chiloguembelina compiled by the pforams@mikrotax project team viewed: 22-7-2019

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