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Protoheterohelix washitensis


Classification: pf_mesozoic -> Heterohelicidae -> Protoheterohelix -> Protoheterohelix washitensis
Sister taxa: P. obscura, P. washitensis, P. sp.,

Taxonomy

Citation: Protoheterohelix washitensis (Tappan, 1940)
Rank: Species
Basionym: Guembelina washitensis

Type images:

Original description: Test tiny, biserial, tapering gradually; chambers globular, closely appressed; sutures distinct, depressed, more angular toward the base, nearly straight among the later chambers; wall calcareous, finely perforate, surface smooth; aperture low, semilunate, at the base of the last formed chamber. Length of holotype, 0.21 mm.; breadth, 0.12mm.; thickness, 0.08 mm.

Entries in the Catalog of original descriptions: Guembelina washitensis


Emended description: Georgescu & Huber. 2009, p.78: "Test is small, loosely twisted, and asymmetrical, and consists of variably overlapping 12 to 15 biserially arranged globular to subglobular chambers. Proloculus (11.8 to 15.9 microns) is slightly larger than second chamber in most of the specimens, or, rarely, chambers gradually increase in size throughout ontogeny in others. Sutures are distinct, straight to slightly curved and depressed, oblique to axis of test growth. Test periphery is broadly rounded. Aperture is a medium-high arch at base of last-formed chamber; it is bordered by asymmetrical periapertural structures, a rim on one side and a subangular ridge on the opposite side. Test surface is smooth. Test wall is calcitic, hyaline, and nannoperforate to microperforate, with pore diameter ranging 0.4 to 0.7 microns." [copied from Chronos database]

Geological Range:
Last occurrence (top): within H. helvetica zone (92.56-93.52Ma, top in Turonian stage). Data source: [copied from Chronos database]
First occurrence (base): within P. ticinensis zone (101.92-103.94Ma, base in Albian 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: Protoheterohelix

    Character matrix

    test outline:Elongatechamber arrangement:Biserialedge view:Compressedaperture:Equatorial
    sp chamber shape:Globularcoiling axis:N/Aperiphery:N/Aaperture border:Thin porticus
    umb chbr shape:Globularumbilicus:Wideperiph margin shape:N/Aaccessory apertures:None
    spiral sutures:Moderately depressedumb depth:N/Awall texture:Smoothshell porosity:Microperforate: <1┬Ám
    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:

    Tappan, H. (1940). Foraminifera from the Grayson formation of Northern Texas. Journal of Paleontology. 14(2): 93-126. gs


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    Protoheterohelix washitensis compiled by the pforams@mikrotax project team viewed: 22-8-2019

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    Short stable page link: http://mikrotax.org/pforams/index.php?id=110448 Go to Archive.is to create a permanent copy of this page - citation notes



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