pforams@mikrotax - Laeviheterohelix flabelliformis pforams@mikrotax - Laeviheterohelix flabelliformis

Laeviheterohelix flabelliformis

Classification: pf_mesozoic -> Heterohelicidae -> Laeviheterohelix -> Laeviheterohelix flabelliformis
Sister taxa: L. dentata, L. flabelliformis, L. glabrans, L. pulchra, L. reniformis, L. turgida, L. sp.


Citation: Laeviheterohelix flabelliformis Nederbragt 1991
taxonomic rank: Species
Basionym: Laeviheterohelix flabelliformis
Taxonomic discussion: Laeviheterohelix flabelliformis has been found in rather poorly preserved samples only. All specimens are recrystallized; as a result, details of the wall structure could not be observed. However, the presence of forms which are morphologically intermediate with L. pulchra, as well as the consistent absence of costae, point to a microperforate test (in H. globulosa and Psg. costellifera specimens from the same samples the presence of costae can always be seen).
Laeviheterohelix flabelliformis is a Turonian homeomorph of the Maastrichtian genus Gublerina, from which it morphologically differs in wall structure, as well as in stratigraphic range. For Gublerina, the chamber arrangement is a reason for distinction of a separate genus; the same should apply to L. flabelliformis. However, because of its limited geographic and stratigraphic range, I prefer to assign it for now to the same genus as its probable ancestor L. pulchra.

Laeviheterohelix flabelliformis seems to be an endemic form with a short biostratigraphic range. Its limited range is comparable to that of the approximately coeval Lunatriella spinifera Richer and Worstell, which was described from the Western Interior of the United States (Richer and Worstell 1970a) and later encountered in West African sediments (Petters 1983). Both forms appear to represent morphologic modifications of L. pulchra, which did not become established as a world-wide species. [copied from Chronos database]

Type images:

Original description: Test biserial throughout, early chambers globular to slightly reniform; adult chambers distinctly reniform, with enlarged apertural flanges separating the widely spaced chambers. Surface smooth, without costae; aperture not observed

Entries in the Catalog of original descriptions: Laeviheterohelix flabelliformis

Character matrix
test outline:Palmatechamber 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:Narrowly roundedaccessory apertures:N/A
spiral sutures:Weakly depressedumb depth:N/Awall texture:Smoothshell porosity:Microperforate: <1┬Ám
umbilical or test sutures:Weakly depressedfinal-whorl chambers:2-4 N.B. These characters are used for advanced search. N/A - not applicable

Most likely ancestor: Laeviheterohelix pulchra - at confidence level 3 (out of 5). Data source: Nederbragt 1991.

Geological Range:
Last occurrence (top): within M. schneegansi zone (89.75-92.51Ma, top in Turonian stage). Data source: [copied from Chronos database]
First occurrence (base): within H. helvetica zone (92.51-93.52Ma, base in Turonian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:


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


Laeviheterohelix flabelliformis compiled by the pforams@mikrotax project team viewed: 16-6-2024

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