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Planoheterohelix reussi


Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix -> Planoheterohelix reussi
Sister taxa: P. globulosa, P. moremani, P. olssoni, P. papula, P. paraglobulosa, P. planata, P. postmoremani, P. praenuttallii, P. reussi, P. rumseyensis, P. sp.,

Taxonomy

Citation: Planoheterohelix reussi (Cushman, 1938)
Rank: Species
Basionym: Guembelina reussi

Type images:

Original description: "Test about 1.5 times as long as broad, rapidly tapering, greatest breadth formed by the last pair of chambers, periphery of early part usually entire, later distinctly indented; chambers of globular, and in the later portion distinctly set apart with a triangular, depressed area between; sutures distinctly depressed throughout; wall smooth, finely perforate, the earliest portion sometimes showing longitudinal rows of perforations; aperture high, semicircular, at the inner border of the chamber."

Entries in the Catalog of original descriptions: Guembelina reussi


Emended description: Haynes, 2015, p. 59: Test is large (average length 5 407 microns, n = 9) and consists of 8 to 14 (n = 9) biserially arranged chambers. A large proloculus (average diameter = 39 microns, n = 7) is followed by globular chambers that generally increase rapidly in size, creating a widening test with a subtriangular outline in side view. The point at which the chambers begin to increase quickly in size is variable, because in many forms the first 3-5 chambers increase slowly in size and then become much larger by the sixth or seventh chamber, again increasing in size gradually throughout the remaining ontogeny. Final chamber is occasionally kummerform. Specimens are broad (average breadth = 193 microns, n = 9), but have a relatively low amount of taper in edge view. Sutures are moderately depressed, straight, and meet the central axis at a right to slightly oblique angle. Aperture is a low-arched semicircle at the base of the final chamber, commonly bordered by an imperforate lip. Test wall is microperforate to finely perforate (average pore diameter = 1.0 micron, n = 2), ornamented with fine discontinuous costae (thickness = 2.9 microns, n = 1) and is calcitic and hyaline. [copied from Chronos database]

Geological Range:
Last occurrence (top): within D. asymetrica zone (84.19-86.71Ma, top in Santonian 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 occurrence data:

Dec 2017 - Plotting of Neptune data has been re-enabled on the Mesozoic pages following revision of the age-models in Neptune. The data is, however, still very sparse for the Early Cretaceous

  • (NB There is no histogram as there are no occurrence records for the taxon in the Neptune database) Parent: Planoheterohelix

    Character matrix

    test outline:Subtriangularchamber arrangement:Biserialedge view:Compressedaperture:Interiomarginal
    sp chamber shape:Inflatedcoiling axis:N/Aperiphery:N/Aaperture border:Thin flange
    umb chbr shape:Inflatedumbilicus:N/Aperiph margin shape:Broadly roundedaccessory apertures:None
    spiral sutures:Strongly depressedumb depth:N/Awall texture:Finely costateshell porosity:
    umbilical or test sutures:Strongly depressedfinal-whorl chambers:2.0-2.0 N.B. These characters are used for advanced search. N/A - not applicable

    References:

    Cushman, J. A. (1938). Cretaceous species of Guembelina and related genera. Contributions from the Cushman Laboratory for Foraminiferal Research. 14: 2-28. gs

    Haynes, S., Huber, B. T. & MacLeod, K. G. (2015). Evolution and phylogeny of mid-Cretaceous (Albian-Coniacian) biserial planktic foraminifera. Journal of Foraminiferal Research. 44: 42-81. gs


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    Planoheterohelix reussi compiled by the pforams@mikrotax project team viewed: 17-10-2019

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110409 Go to Archive.is to create a permanent copy of this page - citation notes



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