Abstract

A new species of the genus Nemkovella (Nemkovella rota n. sp.) is described from the early Cuisian (early Eocene) of southern France. The presence of a discocyclinid-type microspheric juvenarium and the absence of annular stolons permit this generic assignation. The most distinctive characteristic of this new species is the presence of numerous small ribs. Orthophragminid (Discocyclinidae and Orbitoclypeidae) species with numerous small ribs have been traditionally assigned to the genus Actinocyclina Gumbel 1870. However, different species of both Discocyclina and Nemkovella, as well as other orthophragminid genera such as Pseudophragmina and Orbitoclypeus, also have ribs as a specific character. Because Actinocyclina is characterized exclusively by the presence of ribs, and this is a specific character common to several genera, then Actinocyclina must be considered invalid. Moreover, because the generotype of Actinocyclina has a discocyclinid-type microspheric juvenarium and annular stolons, it is herein reassinged to the genus Discocyclina as a ribbed species, D. radians (d'Archiac).

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