pforams@mikrotax - Planoheterohelix praenuttallii

Planoheterohelix praenuttallii

Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix -> Planoheterohelix praenuttallii
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 praenuttallii Haynes, Huber & MacLeod 2015
Rank: Species
Basionym: Planoheterohelix praenuttalli Haynes, Huber & MacLeod 2015

Type images:

Original description: Test relatively large (typically greater than 300 microns in length, average is 304 microns, n = 11), broadly rounded, consists of 9 to 12 chambers (n = 12) that are biserially arranged and globular throughout. The diameter of the proloculus is variable (range = 15 to 32 microns, n = 7) and subsequent chambers rapidly increase in size, resulting in a strongly tapered, subtriangular outline in side and edge views. Sutures are straight, strongly depressed, and generally meet the central axis at a right angle. Aperture is a symmetrical semicircular, low, broad arch at the base of the final chamber, bordered by an imperforate lip. Periapertural flanges are absent. Test wall is calcitic and hyaline. Chamber surface is finely perforate to macroperforate (pore diameter = 0.9 to 3.2 microns, n = 2) and is ornamented with costae that vary from almost completely smooth to those with discontinuous costae that are up to 4.3-microns thick. Distinguishing features. Planoheterohelix praenuttalli is generally large, strongly tapering, and almost as broad (in edge view) as it is wide (in side view).

Entries in the Catalog of original descriptions: Planoheterohelix praenuttalli

Emended description:


Wall type:


Character matrix
test outline:Triangularchamber arrangement:Biserialedge view:Equally biconvexaperture:Interiomarginal
sp chamber shape:Globularcoiling axis:N/Aperiphery:N/Aaperture border:Thick flange
umb chbr shape:Globularumbilicus:N/Aperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Strongly depressedumb depth:N/Awall texture:Finely costateshell porosity:Finely Perforate: 1-2.5┬Ám
umbilical or test sutures:Strongly 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 D. concavata zone (86.71-89.91Ma, top in Coniacian stage). Data source: [copied from Chronos database]
First occurrence (base): within H. helvetica zone (92.56-93.52Ma, base in Turonian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:


Haynes, S., Huber, B. T. & MacLeod, K. G. (2015). Evolution and phylogeny of mid-Cretaceous (Albian-Coniacian) biserial planktic foraminifera. Journal of Foraminiferal Research. 44: 42-81. gs


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

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