Original description: Early part of test broadly flaring with globular chambers, later with more lentil shaped chambers and subparallel sides; finely to coarsely costate surface texture. Aperture a high, narrow arch bordered by a narrow, imperforate lip. Chamber sutures imperforate, depressed, convex toward later chambers; zig-zag median suture twice the width fo the other sutures.
Entries in the Catalog of original descriptions: Heterohelix sphenoides
|test outline:||Elongate||chamber arrangement:||Biserial||edge view:||Compressed||aperture:||Interiomarginal|
|sp chamber shape:||Inflated||coiling axis:||N/A||periphery:||N/A||aperture border:||Thin flange|
|umb chbr shape:||Inflated||umbilicus:||N/A||periph margin shape:||Broadly rounded||accessory apertures:||None|
|spiral sutures:||Weakly depressed||umb depth:||N/A||wall texture:||Finely costate||shell porosity:||Microperforate: <1µm|
|umbilical or test sutures:||Weakly depressed||final-whorl chambers:||2.0-2.0||N.B. These characters are used for advanced search. N/A - not applicable|
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 D. concavata zone (86.71-89.91Ma, base in Turonian stage). Data source: [copied from Chronos database]
Plot of range and occurrence data:
Planoheterohelix sphenoides compiled by the pforams@mikrotax project team viewed: 29-3-2023
Short stables page link: https://mikrotax.org/pforams/index.php?id=110288 Go to Archive.is to create a permanent copy of this page - citation notes
The use of double quote for the genus does not imply the use of brackets for the authority. H. sphenoides is the type species of Planulitella Georgescu, 2010 (a subjective junior synonym of Heterohelix in the opinion of Mikrotax, isn't it?).
Thanks - I've corrected the brackets in the citation now. The genera in the Heterohelicidae are in a state of flux so that is a matter for Brian, but we are puting the new genera etc into the catalog.