Original Description Test free; chambers inflated, biserially arranged throughout or planispiral in early stage and biserial in adult stage, tapering into distinct spines. Sutures depressed; wall calcareous, finely perforate; surface smooth or hispid or striate; aperture interiomarginal, an arch or an asymmetrical comma-shaped slit extending up the apertural face, usually placed more towards one side of the test. Size: Etymology: The genus is named for F. Grimsdale in recognition of his contributions on the value and use of planktonic Foraminifera as stratigraphic index fossils. Extra details from original publication Observed stratigraphie range. - Turonian and/or Coniacian.
Remarks. Grimsdaleinella, n.gen. differs from Chiloguembelina Loeblich & Tappan in possessing chambers with distinct, tapering spines. Grimsdaleinella does not have the apertural necklike extension which is typical for Chiloguembelina. It differs from Heterohelix Ehrenberg in having its chambers tapering into distinct spines. Editors' Notes
Bolli, H. M. (1959a). Grimsdaleinella, a new genus of the foraminiferal family Heterohelicidae. Eclogae Geologicae Helvetiae. 52(1): 1-4. gsVO
Grimsdaleinella compiled by the pforams@mikrotax project teamviewed: 8-2-2023