pforams@mikrotax - Planoheterohelix vistulaensis

Planoheterohelix vistulaensis


Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix -> Planoheterohelix vistulaensis
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: "Heterohelix" vistulaensis Peryt 1980
Rank: Species
Basionym: Heterohelix vistulaensis
Taxonomic discussion: Provisionally placed in "Heterohelix" pending taxonomic revision of Late Cretaceous biserial taxa.
From Peryt, 1980: "The position of the last pair of chambers is not in the plane of the other part of the test distinguishes the new species from all species of Heterohelix hitherto described. H. vistulaensis n. sp. is similar to H. pulchra (BROTZEN) in having two reniform terminal chambers but diners in (1) the development of the older part of the test, (2) the size of the ultimate pair of chambers compared with the size of the whole test, (3) the position of the last pair of chambers not in the test axis, (4) smaller test, and- (5) test ornamentation."

Type images:

Original description: Test biserial, usually consisting of 5-6 pairs of chambers; periphery in initial portion entire, later indented; chambers slightly inflated, barrel-shaped to subglobular, increasing regularly in size as added with the exception of chambers of the final pair which increase sharply in size and constitute 1/2-1/3 of test length; chambers of final pair somewhat flattened, reniform, overlapping; chambers of the penultimate pair partly or completely overlapped; chambers of final pair are deflected in one side thus forming a depression between final pair and earlier part of test; final pair of chambers is nearly twice as wide as long and often wider than the length of the test; sutures distinctly depressed, slightly oblique in regard to test axis; wall with discontinuous, delicate costae; primary aperture interiomarginal, a high arch; gerontic specimens with one additional pair of chambers, globular, lying in normal surface to the earlier part of test, and equal in size to the remainder of the test. Specimens included among this species may differ to some extent in test length, in size and shape of the last pair of chambers as well as in degree of its deflection from the axis of test.

Entries in the Catalog of original descriptions: Heterohelix vistulaensis


Emended description:


Morphology:

Wall type:

Size:

Character matrix
test outline:Subtriangularchamber arrangement:Biserialedge view:Compressedaperture:Interiomarginal
sp chamber shape:Reniformcoiling axis:N/Aperiphery:N/Aaperture border:Thin flange
umb chbr shape:Reniformumbilicus:N/Aperiph margin shape:Moderately roundedaccessory apertures:N/A
spiral sutures:Moderately depressedumb depth:N/Awall texture:Finely pustuloseshell 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

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 A. mayaroensis zone (67.30-69.18Ma, base in Maastrichtian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

References:

Peryt, D. (1980). Planktic foraminifera zonation of the Upper Cretaceous in the middle Vistula River valley, Poland. Palaeontologia Polonica. 41: 1-123. gs


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Planoheterohelix vistulaensis 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=110291 Go to Archive.is to create a permanent copy of this page - citation notes



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