Streptochilus


Classification: pf_cenozoic -> microperforate -> Chiloguembelinidae -> Streptochilus
Sister taxa: Chiloguembelina, Streptochilus,
Daughter taxa: (blue => in age window 0-300Ma)
Distinguished from Chiloguembelina ototara and Chiloguembelina crinita by the more compressed and tapering test and smoother test surface.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Streptochilus Bronnimann and Resig, 1971
Rank: Genus
Type species: Bolivina tokelauae Boersma, 1969 (in Kierstead and others, 1969; =Bolivina globulosa Cushman, 1933, according to Resig and Kroopnick, 1983)
Taxonomic discussion: Loeblich and Tappan (1988) removed Laterostomella from the Buliminidae, where it was originally assigned by de Klasz and Re½rat (1962), placed it in the Chiloguembelinidae and designated Streptochilus as its junior synonym. However, in their comparison of these two genera, de Klasz and others (1989) presented evidence that Laterostomella is a benthic taxon and agreed with other authors (e.g., Bronnimann and Resig, 1971; Kennett and Srinivasan, 1983; Resig and Kroopnick, 1983; Poore and Gosnell, 1985) that Streptochilus probably evolved from Chiloguembelina, and should be assigned to the Chiloguembelinidae. Stable isotopic evidence that Streptochilus is a planktonic taxon was presented by Resig and Kroopnick (1983). [Huber et al. 2006]

Catalog entries: Streptochilus;

Type images:

Distinguishing features: Distinguished from Chiloguembelina by the presence of an internal plate connecting successive foramina (Poore and Gosnell, 1987, pl. 1, figs. 11, 14), a prominent extension of an apertural collar, and a smooth to granular rather than pustulose to costate surface texture.

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 from Chiloguembelina by the presence of an internal plate connecting successive foramina (Poore and Gosnell, 1987, pl. 1, figs. 11, 14), a prominent extension of an apertural collar, and a smooth to granular rather than pustulose to costate surface texture.
[Huber et al. 2006]

Test morphology: “Test biserial sometimes twisted; wall calcareous perforate; aperture high arch, eccentric in position, extending from the base of the last chamber onto the apertural face. On the outside margin a collar borders the aperture. Near the base of the inside margin, the collar and apertural edge are turned inward, producing a plate-like connection with the proximal margin of the collar of the previous aperture. The length of the test varies between 75 and 300 microns” (Bronnimann and Resig, 1971, p. 1288).
[Huber et al. 2006]

Biogeography and Palaeobiology


Phylogenetic relations: Probably derived from Chiloguembelina ototara during the late Eocene through infolding of the inner margin of the aperture.
[Huber et al. 2006]

Most likely ancestor: Chiloguembelina - at confidence level 4 (out of 5). Data source: Huber et al. 2006, f16.2.

Biostratigraphic distribution

Geological Range:
Notes: Middle Eocene (Zone E10) to Recent.
STABLE ISOTOPE PALEOBIOLOGY. __dern Streptochilus globulosum indicate intermediate values for oxygen and carbon stable isotope values, suggestive of a thermocline-dwelling habitat (Resig and Kroopnick, 1983). No data available for Eocene taxa.
[Huber et al. 2006]
Last occurrence (top): in lower part of Rupelian Stage (31% up, 32.1Ma, in Rupelian stage). Data source: Total of range of species in this database
First occurrence (base): in upper part of Lutetian Stage (69% up, 43.2Ma, in Lutetian stage). Data source: Total of range of species in this database

Plot of occurrence data:

Primary source for this page: Huber et al. 2006 - Atlas of Eocene Planktonic Foraminifera, chapter 16, p. 476

References:

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

Cushman, J.A., (1933). Some new foraminiferal genera. Contributions from the Cushman Laboratory for Foraminiferal Research, 9(2): 32-38.

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. et al. (Editors), Atlas of Eocene Planktonic Foraminifera, Cushman Foundation Special Publication 41. Cushman Foundation Special Publication. 41 Allen Press, Lawrence, Kansas, pp. 461-508.

Kennett, J.P. & Srinivasan, M.S., (1983). Neogene Planktonic Foraminifera. Hutchinson Ross Publishing Co., Stroudsburg, Pennsylvania, 1-265 pp.

Kierstead, C.H.; Leidy, R.; Fleisher, R.L. & Boersma, A., (1969). Neogene zonation of tropical Pacific cores. In: Brönnimann, P. and Renz, H.H. (Editors), Proceedings of the First International Conference on Planktonic Microfossiis, Geneva, . Brill, Leiden, pp. 328-338.

Loeblich, A.R., Jr. & Tappan, H., (1988). Foraminiferal Genera and Their Classification (Volume I-II). Van Nostrand Reinhold Co., New York, 1059 pp.

Poore, R.Z. & Gosnell, L.B., (1985). Apertural features and surface texture of upper Paleogene biserial planktonic foraminifers: Links between Chiloguembelina and Streptochilus. Journal of Foraminiferal Research, 15: 1-5.

Poore & Gosnell 1987 [sorry, not in our bibliography yet]

Resig, J.M. & Kroopnick, P.M., (1983). Isotopic and distributional evidence of a planktonic habit for the foraminiferal genus Streptochilus Bronnimann and Resig, 1971. Marine Micropaleontology, 8(3): 235-248.


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Streptochilus compiled by the pforams@mikrotax project team viewed: 22-7-2018

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