Discorbacea

Discorbacea is a superfamily of rotaliid foraminifera,^[1] with a range extending from the Middle Triassic to the present, characterized by chambers arranged in a low trochspiral; an umbilical or interiomarginal aperture, with or without supplementary apertures; and a wall structure that is optically radial.^[2][3]

Eight families are currently recognized, further characterized here in.^[3]

• Discorbidae – Discorbacea in which each chamber is partly divided by an imperforate wall and the umbilical area partly is covered by chamber extensions. Discorbis, Neoeponides
• Bagginidae – Discorbacea with an overall finely perforate test, but imperforate in a part of ventral side Baggina, Cancris
• Eponididae – in which the aperture is interiomarginal and slitlike (or a narrow arch) or areal and cribrate. Eponides, Joanella, Paumotua, Poroeponides
• Heleninidae – in which the primary aperture is interiomarginal and secondary apertures are sutural Helenina.
• MIsissippinidae – have distinct, translucent or opaque bands near the periphery on one or both sides; Mississippina, Stomatorbina
• Pegidiidae – in which coiling is a modified trochospiral, with resorbed early chambers and apertures are open ends of tubes on the ventral side Pegidia
• Rotalinidae – have simple chamber interiors, an umbilicus partly covered by chamber extensions or closed, and an aperutre that is a low interiomarginal arch. Gavellinopsis, Nevconorbina, Rosalina
• Sphaeroidinidae – Discorbacea with strongly overlapping chambers, arranged trochospirally or in different planes; and single slitlike or multiple apertures. Sphaeroidina

Two other families were included , the Asterigerinidae and Epistomariidae, which have been removed to the Asterigerinacea. Some now included families such as the Bagginidae were once defined as a subfamily, the Bagginindae, based on the genus Baggina, in the Discorbidae. As a result the discorbid subfamily Discorbine became the present Discorbidae. The Pegidiidae, originally the rotaliitid subfamily Pegidiinae was removed from the Rotaliacea and added to the Discorbacea as a family. Helenina, a genus in the Discorbinae, became the type for its own family, the Heleninidae. Finally the Eponididae was once included in the Orbitoidacea before being made part of the Discorbacea.^[2]

References