pforams@mikrotax - Protoheterohelix washitensis pforams@mikrotax - Protoheterohelix washitensis

Protoheterohelix washitensis


Classification: pf_mesozoic -> Heterohelicidae -> Protoheterohelix -> Protoheterohelix washitensis
Sister taxa: P. obscura, P. washitensis, P. sp.

Taxonomy

Citation: Protoheterohelix washitensis (Tappan, 1940)
Rank: Species
Basionym: Guembelina washitensis

Type images:

Original description: Test tiny, biserial, tapering gradually; chambers globular, closely appressed; sutures distinct, depressed, more angular toward the base, nearly straight among the later chambers; wall calcareous, finely perforate, surface smooth; aperture low, semilunate, at the base of the last formed chamber. 

Entries in the Catalog of original descriptions: Guembelina washitensis


Emended description:

Georgescu & Huber. 2009, p.78: "Test is small, loosely twisted, and asymmetrical, and consists of variably overlapping 12 to 15 biserially arranged globular to subglobular chambers. Proloculus (11.8 to 15.9 microns) is slightly larger than second chamber in most of the specimens, or, rarely, chambers gradually increase in size throughout ontogeny in others. Sutures are distinct, straight to slightly curved and depressed, oblique to axis of test growth. Test periphery is broadly rounded. Aperture is a medium-high arch at base of last-formed chamber; it is bordered by asymmetrical periapertural structures, a rim on one side and a subangular ridge on the opposite side. Test surface is smooth. Test wall is calcitic, hyaline, and nannoperforate to microperforate, with pore diameter ranging 0.4 to 0.7 microns." [copied from Chronos database]

Character matrix
test outline:Elongatechamber arrangement:Biserialedge view:Compressedaperture:Equatorial
sp chamber shape:Globularcoiling axis:N/Aperiphery:N/Aaperture border:Thin porticus
umb chbr shape:Globularumbilicus:Wideperiph margin shape:N/Aaccessory apertures:None
spiral sutures:Moderately depressedumb depth:N/Awall texture:Smoothshell porosity:Microperforate: <1µm
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 H. helvetica zone (92.56-93.52Ma, top in Turonian stage). Data source: [copied from Chronos database]
First occurrence (base): within P. ticinensis zone (101.92-103.94Ma, base in Albian stage). Data source: [copied from Chronos database]

Plot of range and occurrence data:

References:

Tappan, H. (1940). Foraminifera from the Grayson formation of Northern Texas. Journal of Paleontology. 14(2): 93-126. gs

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Protoheterohelix washitensis compiled by the pforams@mikrotax project team viewed: 30-5-2023

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