pforams@mikrotax - Planoheterohelix labellosa

Planoheterohelix labellosa


Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix -> Planoheterohelix labellosa
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.

Taxonomy

Citation: Planoheterohelix labellosa (Nederbragt, 1991)
Rank: Species
Basionym: Heterohelix labellosa Nederbragt, 1991
Taxonomic discussion: Moved here to Planoheterohelix, since the species clearly does not correspond to the revised generic concept of Heterohelix [editor's comment - JRY 2020]

Provisionally placed in "Heterohelix" pending taxonomic revision of Late Cretaceous biserial taxa. "Heterohelix" labellosa includes a range of morphotypes with variable chamber shape and strength of costae. It is probably a descendant of H. globulosa, the only species with which it has a number of characteristics in common. The two resemble each other in type of ornamentation, rate of increase in chamber size during ontogeny and the presence of a bi-apertured terminal chamber in some specimens. Within one sample, however, "H." labellosa and P. globulosa form distinct populations, with H. labellosa being on the average larger, having more reniform chambers and consistently showing relict apertural flanges along the median suture. [copied from Chronos database]

Type images:

Original description: Test biserial, sides rapidly flaring in the juvenile, sides subparallel in the adult. Juvenile chambers globular, adult chambers subglobular to reniform. Test covered with distinct continuous costae, with fine to medium sized pores in between the costae; sutures depressed. Aperture with small flanges, both the aperture and flanges bordered by a rim, or lip. Relicts of apertural flanges of preceding chambers distinctly visible along the median suture. The terminal chamber may have two apertures

Entries in the Catalog of original descriptions: Heterohelix labellosa


Emended description:


Morphology:

Wall type:

Size:

Character matrix
test outline:Triangularchamber arrangement:Biserialedge view:Compressedaperture:Interiomarginal
sp chamber shape:Globularcoiling axis:N/Aperiphery:N/Aaperture border:Thin flange
umb chbr shape:Globularumbilicus:N/Aperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Moderately depressedumb depth:N/Awall texture:Finely costateshell porosity:Finely Perforate: 1-2.5┬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

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 G. aegyptiaca zone (72.97-74.00Ma, base in Campanian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

References:

Nederbragt, A. J. (1991). Late Cretaceous biostratigraphy and development of Heterohelicidae (planktic foraminifera). Micropaleontology. 37: 329-372. gs


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Planoheterohelix labellosa compiled by the pforams@mikrotax project team viewed: 28-9-2022

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Short stable page link: https://mikrotax.org/pforams/index.php?id=110285 Go to Archive.is to create a permanent copy of this page - citation notes



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