Abstract

The recently emended planktonic foraminifera Thalmanninella is polyphyletic. It includes two lineages that evolved from different ancestors and developed independently. Parathalmanninella nov. gen. is proposed to accommodate species characterized by the presence of petaloid chambers and slightly curved, raised sutures on the spiral side, triangular chambers and radial, depressed chambers on the umbilical side and a small umbilicus. Parathalmanninella includes the following species: Parathalmanninella praebalernaensis (its type species), Parathalmanninella balernaensis, Parathalmanninella appenninica, Parathalmanninella micheli and Parathalmanninella gandolfii. This genus evolved from Ticinella raynaudi. Thalmanninella is re-described in order to include species characterized by chambers that are crescentic on the spiral side and trapezoidal on the umbilical side with curved, raised sutures on both sides of the test, periumbilical ridges, a large umbilicus and a cover-plate. Thalmanninella includes the following species: Thalmanninella brotzeni (its type species), Thalmanninella globotruncanoides, Thalmanninella greenhornensis, Thalmanninella reicheli, Thalmanninella deeckei and Thalmanninella multiloculata.

It is suggested that Thalmanninella evolved from Pseudothalmanninella tehamaensis.

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