pforams@mikrotax - Planoheterohelix pforams@mikrotax - Planoheterohelix

Planoheterohelix


Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix
Sister taxa: Heterohelix, Spiroplecta ⟩⟨ Braunella, Hendersonites, Huberella, Laeviheterohelix, Planoheterohelix, Protoheterohelix, Pseudoguembelina, Pseudotextularia ⟩⟨ Planoglobulina, Ventilabrella, Gublerina, Praegublerina, Sigalia, Racemiguembelina ⟩⟨ Lunatriella, Rectoguembelina, Zeauvigerina
Daughter taxa (time control age-window is: 0-800Ma)
Planoheterohelix globulosa

Planoheterohelix moremani

Planoheterohelix olssoni

Planoheterohelix papula

Planoheterohelix paraglobulosa

Planoheterohelix planata

Planoheterohelix postmoremani

Planoheterohelix praenuttalli

Planoheterohelix reussi

Planoheterohelix rumseyensis

species here provisionally placed in Planohetorohelix
Planoheterohelix labellosa

Planoheterohelix sphenoides

Planoheterohelix stenopos

Planoheterohelix vistulaensis

Planoheterohelix sp.
Specimens which cannot be assigned to established species

Taxonomy

Citation: Planoheterohelix Georgescu & Huber, 2009
taxonomic rank: Genus
Synonyms:

Original description: Description. Test is biserial throughout. Proloculus is small and followed by larger second chamber. Chambers are subglobular to globular in early portion of test and often reniform in adult. Periphery is broadly rounded. Aperture is a low- to medium-high arch situated at base of last-formed chamber; it is bordered by two symmetrically developed flanges. Chamber surface is smooth or with fine longitudinal costae in earlier species and completely costate in evolved ones. Test wall is calcitic, hyaline, microperforate to finely perforate. Pores are situated in intercostal spaces or they might penetrate and interrupt costae.

Entries in the Catalog of original descriptions: Planoheterohelix, Globoheterohelix

Distinguishing features:
Parent taxon (Heterohelicidae): Aperture symmetrical, ranging from a low slit to a high arch at the base of the final chamber, becoming terminal in uniserial taxa.
This taxon: Biserial throughout, aperture symmetrically positioned, wall texture costate.


Emended description:

Test is moderate in size and has globular to subglobular chambers that are biserially arranged throughout and become reniform in some species. Proloculus diameters range from 12–72 µm and subsequent chambers increase in size at varying rates. Aperture is a symmetrical semicircular arch at the base of the final chamber. Sutures are depressed and form at an oblique angle to the central axis. Apertural structures vary but typically consist of symmetrical flanges or an imperforate apertural lip. Test wall is calcitic, ornamented with fine, continuous costae and is microperforate to finely perforate (pore diameter 0.6–3.2 µm).

Morphology:
Test is moderate in size and has globular to subglobular chambers that are biserially arranged throughout and become reniform in some species. Proloculus diameters range from 12–72 µm and subsequent chambers increase in size at varying rates. Aperture is a symmetrical semicircular arch at the base of the final chamber. Sutures are depressed and form at an oblique angle to the central axis. Apertural structures vary but typically consist of symmetrical flanges or an imperforate apertural lip. Test wall is calcitic, ornamented with fine, continuous costae and is microperforate to finely perforate (pore diameter 0.6–3.2 µm).

Geological Range:
Last occurrence (top): at top of P. hariaensis zone (100% up, 66.4Ma, in Maastrichtian stage). Data source: Total of ranges of the species in this database
First occurrence (base): within T. reicheli zone (98.69-98.85Ma, base in Cenomanian stage). Data source: Total of ranges of species in this database

Plot of range and occurrence data:

References:

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


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Planoheterohelix compiled by the pforams@mikrotax project team viewed: 5-10-2024

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