The Wall Structure of Superfamily Miliolacea and Its Lineage in the Gulf Coastal Plain

Abstract

A study of Quinqueloculina tuberculata Cushman and Todd from the Moodys Branch Formation (Jackson, Eocene) at Jackson, Mississippi, eventually evolved into this report on the wall structure of the foraminiferal superfamily Miliolacea and its genera and species from the Gulf Coastal Plain.

From the Moodys Branch Formation Massilina jacksonensis Cushman and its variety punctatocostata Cushman have been assigned to the new genus Tappanella; Quinqueloculina tuberculata Cushman and Todd is considered to be the quinqueloculine stage of Massilina jacksonensis Cushman; Miliola saxorum Lamarck and Miliola jacksonensis Cushman remain as originally described.

From the Weches Formation (Claiborne, Eocene) at Smithville, Texas, Spiroloculina smithvillensis Feray (nomen nudum) is redescribed as Texinaferayi, n. sp., which in turn is selected as the type species for the new genus Texina.

The Cane River Formation (Claiborne, Eocene), a Louisiana lithologic unit equivalent to the Weches of Texas, contains Spiroloculina lamposa Hussey, which has been assigned to the genus Neaguites, new genus.

Species related to Miliola present in the Byram Formation (Oligocene) include: Triloculina mississippiensis Cushman, which has been selected as the type of a new genus Picouina; Spiroloculina byramensis Cushman and Spiroloculina imprimata Cushman, which have been assigned to the new genus Neaguites; and Quinqueloculina byramensis Cushman, which has been assigned to the genus Miliola.

Tappanella, Picouina, Neaguites and Texina, the foraminiferal genera described as new, are calcareous perforate; have pitted chamber walls; and most aper tures have a trematophore (are cribrate). They are assigned to the family Miliolidae, because the type genus Miliola has the same structural features. These features in turn, necessitate an emended diagnosis of the superfamily Miliolacea to accommodate genera with calcareous perforate chamber walls.