pforams@mikrotax - Planoheterohelix reussi

Planoheterohelix reussi

Classification: pf_mesozoic -> Heterohelicidae -> Planoheterohelix -> Planoheterohelix reussi
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 reussi (Cushman, 1938)
Rank: Species
Basionym: Guembelina reussi

Type images:

Original description: "Test about 1.5 times as long as broad, rapidly tapering, greatest breadth formed by the last pair of chambers, periphery of early part usually entire, later distinctly indented; chambers of globular, and in the later portion distinctly set apart with a triangular, depressed area between; sutures distinctly depressed throughout; wall smooth, finely perforate, the earliest portion sometimes showing longitudinal rows of perforations; aperture high, semicircular, at the inner border of the chamber."

Entries in the Catalog of original descriptions: Guembelina reussi

Emended description:

Haynes, 2015, p. 59: Test is large (average length 5 407 microns, n = 9) and consists of 8 to 14 (n = 9) biserially arranged chambers. A large proloculus (average diameter = 39 microns, n = 7) is followed by globular chambers that generally increase rapidly in size, creating a widening test with a subtriangular outline in side view. The point at which the chambers begin to increase quickly in size is variable, because in many forms the first 3-5 chambers increase slowly in size and then become much larger by the sixth or seventh chamber, again increasing in size gradually throughout the remaining ontogeny. Final chamber is occasionally kummerform. Specimens are broad (average breadth = 193 microns, n = 9), but have a relatively low amount of taper in edge view. Sutures are moderately depressed, straight, and meet the central axis at a right to slightly oblique angle. Aperture is a low-arched semicircle at the base of the final chamber, commonly bordered by an imperforate lip. Test wall is microperforate to finely perforate (average pore diameter = 1.0 micron, n = 2), ornamented with fine discontinuous costae (thickness = 2.9 microns, n = 1) and is calcitic and hyaline. [copied from Chronos database]


Wall type:


Character matrix
test outline:Subtriangularchamber arrangement:Biserialedge view:Compressedaperture:Interiomarginal
sp chamber shape:Inflatedcoiling axis:N/Aperiphery:N/Aaperture border:Thin flange
umb chbr shape:Inflatedumbilicus:N/Aperiph margin shape:Broadly roundedaccessory apertures:None
spiral sutures:Strongly depressedumb depth:N/Awall texture:Finely costateshell porosity:
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. asymetrica zone (84.19-86.71Ma, top in Santonian stage). Data source: [copied from Chronos database]
First occurrence (base): within W. archaeocretacea zone (93.52-94.03Ma, base in Cenomanian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:


Cushman, J. A. (1938). Cretaceous species of Guembelina and related genera. Contributions from the Cushman Laboratory for Foraminiferal Research. 14: 2-28. gs V O

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

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


Planoheterohelix reussi compiled by the pforams@mikrotax project team viewed: 4-12-2022

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