pforams@mikrotax - Heterohelix americana

Heterohelix americana


Classification: pf_mesozoic -> Heterohelicidae -> Heterohelix -> Heterohelix americana
Sister taxa: H. americana, H. sp.

Taxonomy

Citation: Heterohelix americana (Ehrenberg, 1844)
Rank: Species
Basionym: Textilaria americana Ehrenberg, 1844

Taxonomic discussion:
Spiroplecta americana and Textilaria americana are now consireder to be different species. T. americana is the type species of Heterohelix.

Type images:

Original description: T. americana, parva, saepius microsc., celerius dilatata laevis, cellulis primis globosis (1/300 lineae l.), dein ovatis, summis in papillam superiorem externam productis subaculeatis.

Cellulae primae nonnullis spirales. Tales formae forsan proprio generi addicendae sunt: Heterohelix.

Translation (from Frerichs & Gaskill 1978)
T . americana, small, more often microscopic, rapidly expanding, smooth, first chamber globular (1/300 of a line), chambers ovate, final chambers produced into a spine.

Entries in the Catalog of original descriptions: Textilaria americana


Emended description: Georgescu & Huber. 2009, p.84-85: "Test is biserial throughout, compressed as seen in edge view. Proloculus is small (10-11 microns in lateral view), spherical, and followed by 10 to 11 biserially arranged chambers that increase gradually in size. An early incipient planispirally coiled stage might be present (Masters, 1980, figs 2b, 3b). Earlier chambers are subrectangular to subtriangular to rounded in shape, the last one or two are subtrapezoidal and with peripheral projections resembling tubulospines. Sutures are distinct, straight, depressed, and oblique to the test axis of growth. Aperture is arcuate, at the base of the last formed chamber, and bordered by small, rarely preserved flanges. Test surface is smooth or occasionally with fine, discrete striae in the peripheral region. Test wall is calcitic, hyaline, nannoperforate to microperforate; pore diameter ranges 0.4-0.8 microns." [copied from Chronos database]

Geological Range:
Last occurrence (top): within W. archaeocretacea zone (93.52-94.03Ma, top in Turonian stage). Data source: [copied from Chronos database]
First occurrence (base): within W. archaeocretacea zone (93.52-94.03Ma, base in Cenomanian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

Character matrix
test outline:Triangularchamber arrangement:Biserialedge view:Compressedaperture:Interiomarginal
sp chamber shape:Globularcoiling axis:N/Aperiphery:N/Aaperture border:Thin flange
umb chbr shape:Globularumbilicus:N/Aperiph margin shape:Broadly roundedaccessory apertures:N/A
spiral sutures:Moderately depressedumb depth:N/Awall texture:Smoothshell porosity:Microperforate: <1µm
umbilical or test sutures:Moderately depressedfinal-whorl chambers:2.0-2.0 N.B. These characters are used for advanced search. N/A - not applicable

References:

Ehrenberg, C. G. (1843b). Verbreitung und Einfluss des mikroscopischen Lebens in Süd- und Nord Amerika. Bericht uber die zu Bekanntmachung geeigneten Verhandlungen der Koniglichen Preussische Akademie der Wissenschaften zu Berlin. 1841: 291-446. gs

Ehrenberg, C. G. (1854). Mikrogeologie: Das Erden und Felsen schaffende Wirken des unsichtbar kleinen selbständigen Lebens auf der Erde. Leopold Voss, Leipzig. 1-374. gs

Georgescu, M. D. & Huber, B. T. (2009). Early evolution of the Cretaceous serial planktic foraminifera (late Albian-Cenomanian). Journal of Foraminiferal Research. 39: 335-360. gs

Missing or ambiguous references: Masters 1980;


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Heterohelix americana compiled by the pforams@mikrotax project team viewed: 20-9-2021

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Short stable page link: https://mikrotax.org/pforams/index.php?id=110284 Go to Archive.is to create a permanent copy of this page - citation notes



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