CATALOG OF ORIGINAL DESCRIPTIONS: Igorina Davidzon, 1976
This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.
Original Description Test free, bilaterally convex. Equatorial outline round, slightly undulate. Axial outline takes the form of a bilateral cone with variable vertex angles. Chambers on sprial side alate, on umbilical side triangular. Umbilicus small or absent. Aperture a slit at the base of the septal surface of the last chamber. Surface of chambers smooth or almost uniformly covered with small spines. [translation from Ellis & Messina Catalog] Extra details from original publication The oldest of the known species of lgorina (I. conicotruncata) has chambers whose umbilical ends are somewhat prolonged, so approaching Morozovella; the presence of spinosity (I. tadjikitanensis) indicates a closeness to Acarinina, while the smooth wall of I. pusilla and I. laevigata indicates closeness to Globorotalia and Planorotalites. However, no tests have the entire set of characters necessary for referral to any of the genera listed. Besides the separate features individually differentiating tests belonging to this genus from other representatives of the family, common specific features are the close appression and alate shape of the chambers, and also the slitlike aperture. Species included:
I. conicotruncata (Subbotina) [Globorotalia conicotruncata, 1947],
I. djanaensis (Shutskaya) [Acarinina tadjikistanensis (Bykova) subsp. djanaensis, 1960],
I. tadjikistanensis (N. Bykova) [Globorotalia tadjikistanensis, 1953],
I. pusilla (Bolli) [Globorotalia pusilla, 1953],
I. laevigata (Bolli) [Globorotalia pusilla subsp. laevigata, 1953].
Geological and geographical distribution: Cosmopolitan in marine Paleocene-Lower Eocene? of all continents.
References:
Davidzon, R. M. (1976). Novyy paleogenovyy rod planktonnykh foraminifer. [A new Paleogene genus of planktonic foraminifera.]. Trudy Vsesoyuznogo Nauchno-issledovatel'skogo Geologorazvedochnogo Neftyanogo Instituta (VNIGNI), Tadzhikskoe Otdelenie,. 183: 197-199. gs
Igorina compiled by the pforams@mikrotax project teamviewed: 9-6-2023
Comments
(0)