pforams@mikrotax - Planoheterohelix planata pforams@mikrotax - Planoheterohelix planata

Planoheterohelix planata

Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix -> Planoheterohelix planata
Sister taxa: P. globulosa, P. moremani, P. olssoni, P. papula, P. paraglobulosa, P. planata, P. postmoremani, P. praenuttallii, P. reussi, P. rumseyensis ⟩⟨ P. labellosa, P. sphenoides, P. stenopos, P. vistulaensis, P. sp.


Citation: Planoheterohelix planata (Cushman, 1938)
Rank: Species
Basionym: Guembelina planata
Synonyms: Guembelina distorta; Heterohelix pachymarginata

Type images:

Original description: Test compressed, about 1½ times as long as broad, rapidly tapering with the greatest breadth formed by the last pair of chambers, periphery slightly keeled in the early portion, in the remainder deeply indentate; chambers broader than high throughout, somewhat compressed, in the adult portion separated by depressed triangular areas; sutures distinctly depressed, somewhat curved; wall smooth, finely perforate, the perforations tending to be in longitudinal lines; aperture high, arched, with distinct lateral flanges running out onto the preceding chamber.

Entries in the Catalog of original descriptions: Guembelina planata, Guembelina distorta, Heterohelix pachymarginata

Emended description:

Georgescu, Saupe & Huber, 2009, p.402: "The test is biserial throughout. The earliest chambers are globular then subrectangular; the later chambers may be reniform in some specimens. Chambers increase gradually in size as added. Sutures are distinct, straight and depressed and slightly oblique to the test axis of growth. The two rows of alternating chambers may diverge in the adult stages of some specimens, but no central area is consistently developed. The periphery of the test is rounded. The aperture is situated at the base of the last-formed chamber and has a medium high to high arch. It is bordered by two small flanges, which are rarely rimmed. Chamber surface is ornamented with fine costae that are 1.8 to 2.5 microns thick. The test wall is microperforate with pore diameters ranging from 0.6 to 0.8 microns. Pores are distributed in the spaces between the costae or can penetrate through the costae." [copied from Chronos database]

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:Moderately roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:N/Awall texture:Finely costateshell porosity:
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

Geological Range:
Last occurrence (top): within A. mayaroensis zone (67.30-69.18Ma, top in Maastrichtian stage). Data source: [copied from Chronos database]
First occurrence (base): within D. asymetrica zone (84.19-86.71Ma, base in Coniacian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:


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

Pessagno, E. A. (1967). Upper Cretaceous planktonic foraminifera from the western Gulf Coastal Plain. Palaeontographica Americana. 5: 245-445. gs V O


Planoheterohelix planata compiled by the pforams@mikrotax project team viewed: 2-4-2023

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AphiaID: 1034800 Nomenclatural data on WoRMS
Short stables page link: Go to to create a permanent copy of this page - citation notes

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