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Heterohelix


Classification: pf_mesozoic -> Heterohelicidae -> Heterohelix
Sister taxa: Braunella, Gublerina, Hendersonites, Heterohelix, Huberella, Laeviheterohelix, Lunatriella, Planoglobulina, Planoheterohelix, Praegublerina, Protoheterohelix, Pseudoguembelina, Pseudotextularia, Racemiguembelina, Rectoguembelina, Sigalia, Spiroplecta, Ventilabrella, Zeauvigerina,
Daughter taxa (blue => in age window 0-300Ma)





Specimens which cannot be assigned to established species

Taxonomy

Citation: Heterohelix Ehrenberg 1843
Rank: Genus
Basionym: Textilaria americana
Type species: Textilaria americana Ehrenberg, 1843
Taxonomic discussion: Heterohelix appears to be transitional between the globular chambered Spiroplecta and Lunatriella whose chambers are laterally much elongated or tubulospinate. As noted by Frerichs and Gaskill (1978, *1182, p. 143), the type species of Heterohelix is Textilaria americana Ehrenberg, 1843 (*1059) by original monotypy (hence Cushman's, 1927, *746, p. 190, designation of Spiroplecta americana as the type of Heterohelix is invalid). Textilaria americana was first illustrated by Ehrenberg (1854, *1068, pl. 32 I, fig. 4a), and similar specimens were illustrated by Frerichs and Gaskill. The latter authors regarded Ehrenberg's pl. 32 I, figs. 13, 14 of Spiroplecta americana to be the microspheric generation of Heterohelix americana.

Type images:

Original description: Heterohelix:

Entries in the Catalog of original descriptions: Heterohelix;

Short diagnosis: Test with early chambers in a tiny planispiral coil, at least in the microspheric generation, later with biserially arranged inflated to globular chambers, final one to two pairs of chambers subtriangular in outline with a short blunt spine at the outer angle of the chamber, sutures depressed; wall calcareous, perforate, ornamented with numerous fine longitudinal striae; aperture a high narrow arch at the base of the last chamber.

Geological Range:
Last occurrence (top): within Maastrichtian Stage (66.04-72.05Ma, top in Maastrichtian stage). Data source: Total of range of species in this database
First occurrence (base): within Cenomanian Stage (93.90-100.50Ma, base in Cenomanian stage). Data source: Total of range of species in this database

Plot of occurrence data:

NB Plotting of Neptune data has been disabled on the Mesozoic pages because the dataset is both small and badly affected by a few sites with erroneous age models (our obs Huber, Petrizzo, Young, Nov 2016). The data can still be viewed via the range plottertool - tools menu.

References:

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


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Heterohelix compiled by the pforams@mikrotax project team viewed: 25-11-2017

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